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Sample records for 3c surface seismic

  1. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    SciTech Connect

    Bjorn N.P. Paulsson

    2002-09-01

    Borehole seismology is the highest resolution geophysical imaging technique available to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This proposal takes direct aim at this shortcoming. P/GSI is developing a 400 level 3C clamped downhole seismic receiver array for borehole seismic 3D imaging. This array will remove the acquisition barrier to record the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. 3D VSP and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for economic use of 3D borehole seismic imaging for reservoir characterization and monitoring. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver array will furthermore facilitate 9C reservoir imaging. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of the rock and the fluid types. The data quality and the data volumes from a 400 level 3C array will allow us to develop the data processing technology necessary for high resolution reservoir imaging.

  2. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    SciTech Connect

    Bjorn N.P Paulsson

    2002-05-01

    Borehole seismology is the highest resolution geophysical imaging technique available to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This proposal takes direct aim at this shortcoming. P/GSI is developing a 400 level 3C clamped downhole seismic receiver array for borehole seismic 3D imaging. This array will remove the acquisition barrier to record the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. 3D VSP and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for economic use of 3D borehole seismic imaging for reservoir characterization and monitoring. By using 3C surface seismic or borehole seismic sources the 400 level receiver array will furthermore facilitate 9C reservoir imaging. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of the rock and the fluid types. The data quality and the data volumes from a 400 level 3C array will allow us to develop the data processing technology necessary for high resolution reservoir imaging.

  3. Development of a 400 Level 3C Clamped Downhole Seismic Receiver Array for 3D Borehole Seismic Imaging of Gas Reservoirs

    SciTech Connect

    Bjorn N.P. Paulsson

    2005-08-21

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently hampered by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. Massive 3D VSP{reg_sign} and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver arrays will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of

  4. Development of a 400 Level 3C Clamped Downhole Seismic Receiver Array for 3D Borehole Seismic Imaging of Gas Reservoirs

    SciTech Connect

    Bjorn N.P Paulsson

    2006-05-05

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently hampered by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. Massive 3D VSP{reg_sign} and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver arrays will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of

  5. Development of a 400 Level 3C Clamped Downhole Seismic Receiver Array for 3D Borehole Seismic Imaging of Gas Reservoirs

    SciTech Connect

    Bjorn N. P. Paulsson

    2005-09-30

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently hampered by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. Massive 3D VSP{reg_sign} and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver arrays will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of

  6. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    SciTech Connect

    Bjorn N.P. Paulsson

    2004-12-31

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. Massive 3D VSP{reg_sign} and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver arrays will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of

  7. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    SciTech Connect

    Bjorn N.P. Paulsson

    2005-03-31

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently hampered by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. Massive 3D VSP{reg_sign} and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver arrays will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of

  8. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    SciTech Connect

    Bjorn N.P. Paulsson

    2004-06-30

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. 3D VSP and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver array will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of the rock and the

  9. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    SciTech Connect

    Bjorn N.P. Paulsson

    2002-12-01

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. 3D VSP and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver array will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of the rock and the

  10. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    SciTech Connect

    Bjorn N.P. Paulsson

    2004-05-31

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. 3D VSP and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver array will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of the rock and the

  11. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    SciTech Connect

    Bjorn N.P Paulsson

    2003-09-01

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. 3D VSP and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver array will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of the rock and the

  12. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS.

    SciTech Connect

    Bjorn N.P Paulsson

    2003-01-01

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. 3D VSP and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver array will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of the rock and the

  13. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    SciTech Connect

    Bjorn N.P. Paulsson

    2004-09-30

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. Massive 3D VSP{reg_sign} and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver arrays will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of

  14. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    SciTech Connect

    Bjorn N.P. Paulsson

    2003-12-01

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. 3D VSP and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver array will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of the rock and the

  15. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    SciTech Connect

    Bjorn N.P Paulsson

    2003-07-01

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. 3D VSP and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver array will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of the rock and the

  16. DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

    SciTech Connect

    Bjorn N.P. Paulsson

    2004-05-01

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This project takes direct aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array will remove the technical acquisition barrier for recording the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. 3D VSP and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs for the purpose of improving the recovery of the natural gas resources. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for the economic use of 3D borehole seismic imaging for reservoir characterization and monitoring by allowing the economic recording of the required large data volumes that have a sufficiently dense spatial sampling. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver array will furthermore allow 3D reservoir imaging using 9C data. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of the rock and the

  17. Development of a 400 Level 3C Clamped Downhole Seismic Receiver Array for 3D Borehole Seismic Imaging of Gas Reservoirs

    SciTech Connect

    Bjorn N. P. Paulsson

    2006-09-30

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to perform high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology has been hampered by the lack of acquisition technology necessary to record large volumes of high frequency, high signal-to-noise-ratio borehole seismic data. This project took aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array has removed the technical acquisition barrier for recording the data volumes necessary to do high resolution 3D VSP and 3D cross-well seismic imaging. Massive 3D VSP{reg_sign} and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that promise to take the gas industry to the next level in their quest for higher resolution images of deep and complex oil and gas reservoirs. Today only a fraction of the oil or gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of detailed compartmentalization of oil and gas reservoirs. In this project, we developed a 400 level 3C borehole seismic receiver array that allows for economic use of 3D borehole seismic imaging for reservoir characterization and monitoring. This new array has significantly increased the efficiency of recording large data volumes at sufficiently dense spatial sampling to resolve reservoir complexities. The receiver pods have been fabricated and tested to withstand high temperature (200 C/400 F) and high pressure (25,000 psi), so that they can operate in wells up to 7,620 meters (25,000 feet) deep. The receiver array is deployed on standard production or drill tubing. In combination with 3C surface seismic or 3C borehole seismic sources, the 400

  18. Near-surface Fun with Seismic Data

    NASA Astrophysics Data System (ADS)

    Clapp, M.

    2015-12-01

    What is happening in the near-surface often has a direct effect on human activity. Seismic exploration has routinely targeted geology at depths of kilometers to tens of kilometers. However, these techniques can be applied to answer questions about shallower targets. Several recent experiments demonstrate seismic applicability to near-surface problems. One example is passive seismic monitoring using ambient noise to identify shallow changes and potential hazards in a producing hydrocarbon field. Another example is the use of seismic reflection data from within the water column to determine layering caused by temperature and salinity differences in depth. A third example is identifying historical elevation changes along coast lines using seismic reflection data. These examples show that exploration seismic methods can be effectively used for a variety of near-surface applications.

  19. Atomic-scale recognition of surface structure and intercalation mechanism of Ti3C2X.

    PubMed

    Wang, Xuefeng; Shen, Xi; Gao, Yurui; Wang, Zhaoxiang; Yu, Richeng; Chen, Liquan

    2015-02-25

    MXenes represent a large family of functionalized two-dimensional (2D) transition-metal carbides and carbonitrides. However, most of the understanding on their unique structures and applications stops at the theoretical suggestion and lack of experimental support. Herein, the surface structure and intercalation chemistry of Ti3C2X are clarified at the atomic scale by aberration-corrected scanning transmission electron microscope (STEM) and density functional theory (DFT) calculations. The STEM studies show that the functional groups (e.g., OH(-), F(-), O(-)) and the intercalated sodium (Na) ions prefer to stay on the top sites of the centro-Ti atoms and the C atoms of the Ti3C2 monolayer, respectively. Double Na-atomic layers are found within the Ti3C2X interlayer upon extensive Na intercalation via two-phase transition and solid-solution reactions. In addition, aluminum (Al)-ion intercalation leads to horizontal sliding of the Ti3C2X monolayer. On the basis of these observations, the previous monolayer surface model of Ti3C2X is modified. DFT calculations using the new modeling help to understand more about their physical and chemical properties. These findings enrich the understanding of the MXenes and shed light on future material design and applications. Moreover, the Ti3C2X exhibits prominent rate performance and long-term cycling stability as an anode material for Na-ion batteries. PMID:25688582

  20. Martian seismicity through time from surface faulting

    NASA Technical Reports Server (NTRS)

    Golombek, M. P.; Tanaka, Kenneth L.; Banerdt, W. B.; Tralli, D.

    1991-01-01

    An objective of future Mars missions involves emplacing a seismic network on Mars to determine the internal structure of the planet. An argument based on the relative geologic histories of the terrestrial planets suggests that Mars should be seismically more active than the Moon, but less active than the Earth. The seismicity is estimated which is expected on Mars through time from slip on faults visible on the planets surface. These estimates of martian seismicity must be considered a lower limit as only structures produced by shear faulting visible at the surface today are included (i.e., no provision is made for buried structures or non-shear structures); in addition, the estimate does not include seismic events that do not produce surface displacement (e.g., activity associated with hidden faults, deep lithospheric processes or volcanism) or events produced by tidal triggering or meteorite impacts. Calibration of these estimates suggests that Mars may be many times more seismically active than the Moon.

  1. Development and Test of a 1,000 Level 3C Fiber Optic Borehole Seismic Receiver Array Applied to Carbon Sequestration

    SciTech Connect

    Paulsson, Bjorn N.P.

    2015-02-28

    To address the critical site characterization and monitoring needs for CCS programs, US Department of Energy (DOE) awarded Paulsson, Inc. in 2010 a contract to design, build and test a fiber optic based ultra-large bandwidth clamped borehole seismic vector array capable of deploying up to one thousand 3C sensor pods suitable for deployment into high temperature and high pressure boreholes. Paulsson, Inc. has completed a design or a unique borehole seismic system consisting of a novel drill pipe based deployment system that includes a hydraulic clamping mechanism for the sensor pods, a new sensor pod design and most important – a unique fiber optic seismic vector sensor with technical specifications and capabilities that far exceed the state of the art seismic sensor technologies. These novel technologies were all applied to the new borehole seismic system. In combination these technologies will allow for the deployment of up to 1,000 3C sensor pods in vertical, deviated or horizontal wells. Laboratory tests of the fiber optic seismic vector sensors developed during this project have shown that the new borehole seismic sensor technology is capable of generating outstanding high vector fidelity data with extremely large bandwidth: 0.01 – 6,000 Hz. Field tests have shown that the system can record events at magnitudes much smaller than M-2.3 at frequencies up to 2,000 Hz. The sensors have also proved to be about 100 times more sensitive than the regular coil geophones that are used in borehole seismic systems today. The fiber optic seismic sensors have furthermore been qualified to operate at temperatures over 300°C (572°F). The fibers used for the seismic sensors in the system are used to record Distributed Temperature Sensor (DTS) data allowing additional value added data to be recorded simultaneously with the seismic vector sensor data.

  2. A prediction of mars seismicity from surface faulting

    USGS Publications Warehouse

    Golombek, M.P.; Banerdt, W.B.; Tanaka, K.L.; Tralli, D.M.

    1992-01-01

    The shallow seismicity of Mars has been estimated by measurement of the total slip on faults visible on the surface of the planet throughout geologic time. Seismicity was calibrated with estimates based on surface structures on the moon and measured lunar seismicity that includes the entire seismogenic lithosphere. Results indicate that Mars is seismically active today, with a sufficient number of detectable marsquakes to allow seismic investigations of its interior.

  3. Global surface wave tomography using seismic hum.

    PubMed

    Nishida, Kiwamu; Montagner, Jean-Paul; Kawakatsu, Hitoshi

    2009-10-01

    The development of global surface wave tomography using earthquakes has been crucial to exploration of the dynamic status of Earth's deep. It is naturally believed that only large earthquakes can generate long-period seismic waves that penetrate deep enough into Earth for such exploration. The discovery of seismic hum, Earth's background free oscillations, which are randomly generated by oceanic and/or atmospheric disturbances, now provides an alternative approach. We present results of global upper-mantle seismic tomography using seismic hum and without referring to earthquakes. At periods of 100 to 400 seconds, the phase-velocity anomalies of Rayleigh waves are measured by modeling the observed cross-correlation functions between every pair of stations from among 54 globally distributed seismic stations. The anomalies are then inverted to obtain the three-dimensional S-wave velocity structure in the upper mantle. Our technique provides a new means for exploring the three-dimensional structure of the interior of terrestrial planets with an atmosphere and/or oceans, particularly Mars. PMID:19797654

  4. Global surface wave tomography using seismic hum.

    PubMed

    Nishida, Kiwamu; Montagner, Jean-Paul; Kawakatsu, Hitoshi

    2009-10-01

    The development of global surface wave tomography using earthquakes has been crucial to exploration of the dynamic status of Earth's deep. It is naturally believed that only large earthquakes can generate long-period seismic waves that penetrate deep enough into Earth for such exploration. The discovery of seismic hum, Earth's background free oscillations, which are randomly generated by oceanic and/or atmospheric disturbances, now provides an alternative approach. We present results of global upper-mantle seismic tomography using seismic hum and without referring to earthquakes. At periods of 100 to 400 seconds, the phase-velocity anomalies of Rayleigh waves are measured by modeling the observed cross-correlation functions between every pair of stations from among 54 globally distributed seismic stations. The anomalies are then inverted to obtain the three-dimensional S-wave velocity structure in the upper mantle. Our technique provides a new means for exploring the three-dimensional structure of the interior of terrestrial planets with an atmosphere and/or oceans, particularly Mars.

  5. Seismic noise on Rarotonga: Surface versus downhole

    NASA Astrophysics Data System (ADS)

    Butler, Rhett; Hutt, C. R.

    Seismic noise data are presented from the new Global Seismographic Network station, RAR, on the Island of Rarotonga in the South Pacific. Data from the first new borehole site in the GSN are compared with a surface vault installation. Initial indications from the data show that borehole siting on a small island significantly reduces long-period (>20 s) horizontal seismic noise levels during the daytime, but little or no improvement is evident at periods shorter than 20 s or on the vertical component.The goal of the Incorporated Research Institutions for Seismology (IRIS) GSN program is broad, uniform coverage of the Earth with a 128-station network. To achieve this goal and provide coverage in oceanic areas, many stations will be sited on islands. A major siting consideration for these new stations is whether to build a surface vault or drill a borehole. Neither option is inexpensive. The costs for drilling a cased hole and a borehole sensor are large, but the benefit of a borehole site is that seismic noise is reduced during certain periods when a surface installation may be subject to wind, weather, and thermal effects. This benefit translates into recording greater numbers of smaller earthquakes and higher signal-to-noise ratio.

  6. Submarine seismic monitoring of El Hierro volcanic eruption with a 3C-geophone string: applying new acquisition and data processing techniques to volcano monitoring

    NASA Astrophysics Data System (ADS)

    Jurado, Maria Jose; Ripepe, Maurizio; Lopez, Carmen; Blanco, Maria Jose; Crespo, Jose

    2015-04-01

    A submarine volcanic eruption took place near the southernmost emerged land of the El Hierro Island (Canary Islands, Spain), from October 2011 to February 2012. The Instituto Geografico Nacional (IGN) seismic stations network evidenced seismic unrest since July 2011 and was a reference also to follow the evolution of the seismic activity associated with the volcanic eruption. Right after the eruption onset, in October 2011 a geophone string was deployed by the CSIC-IGN to monitor seismic activity. Monitoring with the seismic array continued till May 2012. The array was installed less than 2 km away from the new vol¬cano, next to La Restinga village shore in the harbor from 6 to 12m deep into the water. Our purpose was to record seismic activity related to the volcanic activity, continuously and with special interest on high frequency events. The seismic array was endowed with 8, high frequency, 3 component, 250 Hz, geophone cable string with a separation of 6 m between them. Each geophone consists on a 3-component module based on 3 orthogonal independent sensors that measures ground velocity. Some of the geophones were placed directly on the seabed, some were buried. Due to different factors, as the irregular characteristics of the seafloor. The data was recorded on the surface with a seismometer and stored on a laptop computer. We show how acoustic data collected underwater show a great correlation with the seismic data recorded on land. Finally we compare our data analysis results with the observed sea surface activity (ash and lava emission and degassing). This evidence is disclosing new and innovative tecniques on monitoring submarine volcanic activity. Reference Instituto Geográfico Nacional (IGN), "Serie El Hierro." Internet: http://www.ign.es/ign/resources /volcanologia/HIERRO.html [May, 17. 2013

  7. Surface modified MXene Ti3C2 multilayers by aryl diazonium salts leading to large-scale delamination

    NASA Astrophysics Data System (ADS)

    Wang, Hongbing; Zhang, Jianfeng; Wu, Yuping; Huang, Huajie; Li, Gaiye; Zhang, Xin; Wang, Zhuyin

    2016-10-01

    Herein we report a simple and facile method to delaminate MXene Ti3C2 multilayers by the assistance of surface modification using aryl diazonium salts. The basic strategy involved the preparation of layered MAX Ti3AlC2 and the exfoliation of Ti3AlC2 into Ti3C2 multilayers, followed by Na+ intercalation and surface modification using sulfanilic acid diazonium salts. The resulting chemically grafted Ti3C2 flakes were characterized by Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) to confirm the presence of the surface organic species. Ultraviolet-visible spectroscopy revealed that surface-modified MXene Ti3C2 sheets disperse well in water and the solutions obey Lambert-Beer's law. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to demonstrate the morphology and structure of delaminating MXene Ti3C2 flakes. The results indicated that chemical modification for MXene multilayers by aryl diazonium salts induced swelling that conversely weakened the bonds between MX layers, hence leading to large-scale delamination of multilayered MXene Ti3C2via mild sonication. Advantages of the present approach rely not only on the simplicity and efficiency of the delamination procedure but also on the grafting of aryl groups to MXene surfaces, highly suitable for further applications of the newly discovered two-dimensional materials.

  8. 3-component HR seismic reflection, a new paradigm for near surface exploration of aquifers and aquitards

    NASA Astrophysics Data System (ADS)

    Pugin, A.; Pullan, S. E.; Oldenborger, G. A.; Crow, H.; Hunter, J. A.; Near Surface Geophysics

    2011-12-01

    The recent development of landstreamers towed by vibroseis sources at the Geological Survey of Canada and the resulting typical acquisition of up to 6 km of seismic line per day, has greatly enhanced our capacity to provide regional data for groundwater modeling. In a single pass of acquisition, the recording of 3-component (3-C) data allows us to observe and process P-waves, S-waves and converted PS-waves. The testing of this technique over various types of unconsolidated sediment has yielded very meaningful observations. We have observed in general that the P-wave is mostly vertically polarised, while the PS wave can be seen in the vertical and the in-line component, and the S-wave can be seen on all receiver-components with a polarisation that may evolve between vertical and horizontal depending on the geological materials encountered. The polarisation of S-wave data is observed whether the seismic source position is in a vertical or in a horizontal mode. The use of common-midpoint, normal-moveout velocity analyses, calibrated with geophysical logs and resistivity profiling data, has shown us that seismic velocities can be used to characterise the lithologies present in the seismic sections. In the St Lawrence Lowlands in eastern Canada, aquifers in the form of tunnel-shaped eskers and coarse sediment layers buried by up to 100 m of glacio-marine silts have been imaged very successfully using this innovative seismic technique. Shear wave seismic sections acquired in this environment provide subsurface resolution on a scale previously only observed using waterborne seismic methods. The sections show erosional surfaces and vertical structures interpreted to be gas and/or water escape features present in the silt deposits. These high-resolution data are providing critical new insights into the structural geometry of this type of aquitard. In central and western Canada our seismic system has been used for regional mapping of buried valley aquifers protected and

  9. Kinetic surface roughening and wafer bow control in heteroepitaxial growth of 3C-SiC on Si(111) substrates

    PubMed Central

    Wang, Li; Walker, Glenn; Chai, Jessica; Iacopi, Alan; Fernandes, Alanna; Dimitrijev, Sima

    2015-01-01

    A thin, chemically inert 3C-SiC layer between GaN and Si helps not only to avoid the “melt-back” effect, but also to inhibit the crack generation in the grown GaN layers. The quality of GaN layer is heavily dependent on the unique properties of the available 3C-SiC/Si templates. In this paper, the parameters influencing the roughness, crystalline quality, and wafer bow are investigated and engineered to obtain high quality, low roughness 3C-SiC/Si templates suitable for subsequent GaN growth and device processing. Kinetic surface roughening and SiC growth mechanisms, which depend on both deposition temperature and off-cut angle, are reported for heteroepitaxial growth of 3C-SiC on Si substrates. The narrower terrace width on 4° off-axis Si enhances the step-flow growth at 1200 °C, with the roughness of 3C-SiC remaining constant with increasing thickness, corresponding to a scaling exponent of zero. Crack-free 3C-SiC grown on 150-mm Si substrate with a wafer bow of less than 20 μm was achieved. Both concave and convex wafer bow can be obtained by in situ tuning of the deposited SiC layer thicknesses. The 3C-SiC grown on off-axis Si, compared to that grown on on-axis Si, has lower surface roughness, better crystallinity, and smaller bow magnitude. PMID:26487465

  10. Kinetic surface roughening and wafer bow control in heteroepitaxial growth of 3C-SiC on Si(111) substrates.

    PubMed

    Wang, Li; Walker, Glenn; Chai, Jessica; Iacopi, Alan; Fernandes, Alanna; Dimitrijev, Sima

    2015-10-21

    A thin, chemically inert 3C-SiC layer between GaN and Si helps not only to avoid the "melt-back" effect, but also to inhibit the crack generation in the grown GaN layers. The quality of GaN layer is heavily dependent on the unique properties of the available 3C-SiC/Si templates. In this paper, the parameters influencing the roughness, crystalline quality, and wafer bow are investigated and engineered to obtain high quality, low roughness 3C-SiC/Si templates suitable for subsequent GaN growth and device processing. Kinetic surface roughening and SiC growth mechanisms, which depend on both deposition temperature and off-cut angle, are reported for heteroepitaxial growth of 3C-SiC on Si substrates. The narrower terrace width on 4° off-axis Si enhances the step-flow growth at 1200 °C, with the roughness of 3C-SiC remaining constant with increasing thickness, corresponding to a scaling exponent of zero. Crack-free 3C-SiC grown on 150-mm Si substrate with a wafer bow of less than 20 μm was achieved. Both concave and convex wafer bow can be obtained by in situ tuning of the deposited SiC layer thicknesses. The 3C-SiC grown on off-axis Si, compared to that grown on on-axis Si, has lower surface roughness, better crystallinity, and smaller bow magnitude.

  11. Advanced Reservoir Characterization and Development through High-Resolution 3C3D Seismic and Horizontal Drilling: Eva South Marrow Sand Unit, Texas County, Oklahoma

    SciTech Connect

    Wheeler,David M.; Miller, William A.; Wilson, Travis C.

    2002-03-11

    The Eva South Morrow Sand Unit is located in western Texas County, Oklahoma. The field produces from an upper Morrow sandstone, termed the Eva sandstone, deposited in a transgressive valley-fill sequence. The field is defined as a combination structural stratigraphic trap; the reservoir lies in a convex up -dip bend in the valley and is truncated on the west side by the Teepee Creek fault. Although the field has been a successful waterflood since 1993, reservoir heterogeneity and compartmentalization has impeded overall sweep efficiency. A 4.25 square mile high-resolution, three component three-dimensional (3C3D) seismic survey was acquired in order to improve reservoir characterization and pinpoint the optimal location of a new horizontal producing well, the ESU 13-H.

  12. High-efficiency electrochemical hydrogen evolution based on surface autocatalytic effect of ultrathin 3C-SiC nanocrystals.

    PubMed

    He, Chengyu; Wu, Xinglong; Shen, Jiancang; Chu, Paul K

    2012-03-14

    Good understanding of the reaction mechanism in the electrochemical reduction of water to hydrogen is crucial to renewable energy technologies. Although previous studies have revealed that the surface properties of materials affect the catalytic reactivity, the effects of a catalytic surface on the hydrogen evolution reaction (HER) on the molecular level are still not well understood. Contrary to general belief, water molecules do not adsorb onto the surfaces of 3C-SiC nanocrystals (NCs), but rather spontaneously dissociate via a surface autocatalytic process forming a complex consisting of -H and -OH fragments. In this study, we show that ultrathin 3C-SiC NCs possess superior electrocatalytic activity in the HER. This arises from the large reduction in the activation barrier on the NC surface enabling efficient dissociation of H(2)O molecules. Furthermore, the ultrathin 3C-SiC NCs show enhanced HER activity in photoelectrochemical cells and are very promising to the water splitting based on the synergistic electrocatalytic and photoelectrochemical actions. This study provides a molecular-level understanding of the HER mechanism and reveals that NCs with surface autocatalytic effects can be used to split water with high efficiency thereby enabling renewable and economical production of hydrogen.

  13. Experiments on seismic metamaterials: molding surface waves.

    PubMed

    Brûlé, S; Javelaud, E H; Enoch, S; Guenneau, S

    2014-04-01

    Materials engineered at the micro- and nanometer scales have had a tremendous and lasting impact in photonics and phononics. At much larger scales, natural soils civil engineered at decimeter to meter scales may interact with seismic waves when the global properties of the medium are modified, or alternatively thanks to a seismic metamaterial constituted of a mesh of vertical empty inclusions bored in the initial soil. Here, we show the experimental results of a seismic test carried out using seismic waves generated by a monochromatic vibrocompaction probe. Measurements of the particles' velocities show a modification of the seismic energy distribution in the presence of the metamaterial in agreement with numerical simulations using an approximate plate model. For complex natural materials such as soils, this large-scale experiment was needed to show the practical feasibility of seismic metamaterials and to stress their importance for applications in civil engineering. We anticipate this experiment to be a starting point for smart devices for anthropic and natural vibrations. PMID:24745420

  14. Experiments on seismic metamaterials: molding surface waves.

    PubMed

    Brûlé, S; Javelaud, E H; Enoch, S; Guenneau, S

    2014-04-01

    Materials engineered at the micro- and nanometer scales have had a tremendous and lasting impact in photonics and phononics. At much larger scales, natural soils civil engineered at decimeter to meter scales may interact with seismic waves when the global properties of the medium are modified, or alternatively thanks to a seismic metamaterial constituted of a mesh of vertical empty inclusions bored in the initial soil. Here, we show the experimental results of a seismic test carried out using seismic waves generated by a monochromatic vibrocompaction probe. Measurements of the particles' velocities show a modification of the seismic energy distribution in the presence of the metamaterial in agreement with numerical simulations using an approximate plate model. For complex natural materials such as soils, this large-scale experiment was needed to show the practical feasibility of seismic metamaterials and to stress their importance for applications in civil engineering. We anticipate this experiment to be a starting point for smart devices for anthropic and natural vibrations.

  15. Experiments on Seismic Metamaterials: Molding Surface Waves

    NASA Astrophysics Data System (ADS)

    Brûlé, S.; Javelaud, E. H.; Enoch, S.; Guenneau, S.

    2014-04-01

    Materials engineered at the micro- and nanometer scales have had a tremendous and lasting impact in photonics and phononics. At much larger scales, natural soils civil engineered at decimeter to meter scales may interact with seismic waves when the global properties of the medium are modified, or alternatively thanks to a seismic metamaterial constituted of a mesh of vertical empty inclusions bored in the initial soil. Here, we show the experimental results of a seismic test carried out using seismic waves generated by a monochromatic vibrocompaction probe. Measurements of the particles' velocities show a modification of the seismic energy distribution in the presence of the metamaterial in agreement with numerical simulations using an approximate plate model. For complex natural materials such as soils, this large-scale experiment was needed to show the practical feasibility of seismic metamaterials and to stress their importance for applications in civil engineering. We anticipate this experiment to be a starting point for smart devices for anthropic and natural vibrations.

  16. 3. C1XS results - First measurement of enhanced Sodium on the Lunar surface

    NASA Astrophysics Data System (ADS)

    Grande, Manuel; Athiray, Subramania; Narendranath, Shyama; Sreekumar, Parameswaran; Carter, Jimmy

    2015-04-01

    We describe the first unambiguous evidence of enhanced sodium on the lunar surface revealed by the Chandrayaan-1 X-ray Spectrometer (C1XS).The C1XS on board the Chandrayaan-1 spacecraft was designed to map the surface elemental chemistry of the Moon using the X-ray fluorescence (XRF) technique. During the nine months of remote sensing observations (November 2008-August 2009), C1XS measured XRF emission from the Moon under several solar flare conditions. A summary of the entire C1XS observations and data selection methods are presented. Surface elemental abundances of major rock-forming elements viz., Mg, Al, Si and Ca as well as Na derived from C1XS data corresponding to certain nearside regions of the Moon are reported here. We also present a detailed description of the analysis techniques including derivation of XRF line fluxes and conversion to elemental abundances. The derived abundances of Na(2-3 wt%) are significantly higher than what has been known from earlier studies. We compare the surface chemistry of C1XS observed regions with the highly silicic compositions (intermediate plagioclase) measured by the Diviner Radiometer instrument on board Lunar Reconnaissance Orbiter (LRO) in those regions. Elemental maps of the nearside Lunar highlands are presented. The compositions determined from C1XS tend to support recent theories and findings of intermediate plagioclase on the Moon. However,precise Ca and Na abundance measurements are required on a global scale to address the evolution of the lunar surface.

  17. Calving seismicity from iceberg-sea surface interactions

    USGS Publications Warehouse

    Bartholomaus, T.C.; Larsen, C.F.; O'Neel, S.; West, M.E.

    2012-01-01

    Iceberg calving is known to release substantial seismic energy, but little is known about the specific mechanisms that produce calving icequakes. At Yahtse Glacier, a tidewater glacier on the Gulf of Alaska, we draw upon a local network of seismometers and focus on 80 hours of concurrent, direct observation of the terminus to show that calving is the dominant source of seismicity. To elucidate seismogenic mechanisms, we synchronized video and seismograms to reveal that the majority of seismic energy is produced during iceberg interactions with the sea surface. Icequake peak amplitudes coincide with the emergence of high velocity jets of water and ice from the fjord after the complete submergence of falling icebergs below sea level. These icequakes have dominant frequencies between 1 and 3 Hz. Detachment of an iceberg from the terminus produces comparatively weak seismic waves at frequencies between 5 and 20 Hz. Our observations allow us to suggest that the most powerful sources of calving icequakes at Yahtse Glacier include iceberg-sea surface impact, deceleration under the influence of drag and buoyancy, and cavitation. Numerical simulations of seismogenesis during iceberg-sea surface interactions support our observational evidence. Our new understanding of iceberg-sea surface interactions allows us to reattribute the sources of calving seismicity identified in earlier studies and offer guidance for the future use of seismology in monitoring iceberg calving.

  18. Surface Modification of Cr3C2-NiCr Cermet Coatings by Direct Diode Laser Remelting Process

    NASA Astrophysics Data System (ADS)

    Abe, Nobuyuki; Morimoto, Junji; Fukuhra, Shinji; Yamada, Katsuhiro; Tsukamoto, Masahiro

    Thermal spraying technology has been used for the improvement of wear resistance, erosion resistance, heat resistance and corrosion resistance. Corrosion, wear and abrasion resistance of the substrate materials were significantly improved by the paint coatings. These organic paint coatings, however, did not endure high temperatures and did not adhere well. Modern high performance machinery parts subjected to the extremes of temperature and mechanical stress, needs surface protection against high temperature corrosive media, and mechanical wear and tear. Chromium carbide based materials are commonly used for high temperature wear applications. In this study, we treated Cr3C2-NiCr coatings by laser irradiation treatment and examined its hardness in comparison with that formed by HVOF process. Consequently, the average hardness of laser irradiated Cr3C2-NiCr coating was found out to be higher than that of HVOF coating. The laser-treated Cr3C2-35%NiCr coating further improved the solid particle erosion resistance by a factor of almost twice.

  19. Scattered surface wave energy in the seismic coda

    USGS Publications Warehouse

    Zeng, Y.

    2006-01-01

    One of the many important contributions that Aki has made to seismology pertains to the origin of coda waves (Aki, 1969; Aki and Chouet, 1975). In this paper, I revisit Aki's original idea of the role of scattered surface waves in the seismic coda. Based on the radiative transfer theory, I developed a new set of scattered wave energy equations by including scattered surface waves and body wave to surface wave scattering conversions. The work is an extended study of Zeng et al. (1991), Zeng (1993) and Sato (1994a) on multiple isotropic-scattering, and may shed new insight into the seismic coda wave interpretation. The scattering equations are solved numerically by first discretizing the model at regular grids and then solving the linear integral equations iteratively. The results show that scattered wave energy can be well approximated by body-wave to body wave scattering at earlier arrival times and short distances. At long distances from the source, scattered surface waves dominate scattered body waves at surface stations. Since surface waves are 2-D propagating waves, their scattered energies should in theory follow a common decay curve. The observed common decay trends on seismic coda of local earthquake recordings particular at long lapse times suggest that perhaps later seismic codas are dominated by scattered surface waves. When efficient body wave to surface wave conversion mechanisms are present in the shallow crustal layers, such as soft sediment layers, the scattered surface waves dominate the seismic coda at even early arrival times for shallow sources and at later arrival times for deeper events.

  20. The seismic effect of impacts on asteroid surface morphology

    NASA Astrophysics Data System (ADS)

    Richardson, James Edward, Jr.

    Impact-induced seismic vibrations have long been suspected of being an important surface modification process on small satellites and asteroids. In this study, I use a series of linked seismic and geomorphic models to investigate the process in detail. I begin by developing a basic theory for the propagation of seismic energy in a highly fractured asteroid, and I use this theory to model the global vibrations experienced on the surface of an asteroid following an impact. These synthetic seismograms are then applied to a model of regolith resting on a slope, and the resulting downslope motion is computed for a full range of impactor sizes. Next, this computed downslope regolith flow is used in a morphological model of impact crater degradation and erasure, showing how topographic erosion accumulates as a function of time and the number of impacts. Finally, these results are applied in a stochastic cratering model for the surface of an Eros-like body (same volume and surface area as the asteroid), with craters formed by impacts and then erased by the effects of superposing craters, ejecta coverage, and seismic shakedown. This simulation shows good agreement with the observed 433 Eros cratering record at a Main Belt exposure age of 400 +/- 200 Myr, including the observed paucity of small craters. The lowered equilibrium numbers floss rate = production rate) for craters less than ~100 m in diameter is a direct result of seismic erasure, which requires less than a meter of mobilized regolith to reproduce the NEAR observations. This study also points to an upper limit on asteroid size for experiencing global, surface-modifying, seismic effects from individual impacts of about 70- 100 km (depending upon asteroid seismic properties). Larger asteroids will experience only local seismic effects from individual impacts. In addition to the study of global seismic effects on asteroids, a chapter is also included which details the impact ejecta plume modeling I have done for the

  1. A new passive seismic method based on seismic interferometry and multichannel analysis of surface waves

    NASA Astrophysics Data System (ADS)

    Cheng, Feng; Xia, Jianghai; Xu, Yixian; Xu, Zongbo; Pan, Yudi

    2015-06-01

    We proposed a new passive seismic method (PSM) based on seismic interferometry and multichannel analysis of surface waves (MASW) to meet the demand for increasing investigation depth by acquiring surface-wave data at a low-frequency range (1 Hz ≤ f ≤ 10 Hz). We utilize seismic interferometry to sort common virtual source gathers (CVSGs) from ambient noise and analyze obtained CVSGs to construct 2D shear-wave velocity (Vs) map using the MASW. Standard ambient noise processing procedures were applied to the computation of cross-correlations. To enhance signal to noise ratio (SNR) of the empirical Green's functions, a new weighted stacking method was implemented. In addition, we proposed a bidirectional shot mode based on the virtual source method to sort CVSGs repeatedly. The PSM was applied to two field data examples. For the test along Han River levee, the results of PSM were compared with the improved roadside passive MASW and spatial autocorrelation method (SPAC). For test in the Western Junggar Basin, PSM was applied to a 70 km long linear survey array with a prominent directional urban noise source and a 60 km-long Vs profile with 1.5 km in depth was mapped. Further, a comparison about the dispersion measurements was made between PSM and frequency-time analysis (FTAN) technique to assess the accuracy of PSM. These examples and comparisons demonstrated that this new method is efficient, flexible, and capable to study near-surface velocity structures based on seismic ambient noise.

  2. Growth of Defect-Free 3C-Sic on 4H- and 6H-SIC Mesas Using Step-Free Surface Heteroepitaxy

    NASA Technical Reports Server (NTRS)

    Neudeck, Philip G.; Powell, J. Anthony; Trunek, Andrew J.; Huang, Xianrong R.; Dudley, Michael

    2002-01-01

    A new growth process, herein named step-free surface heteroepitaxy, has achieved 3C-SiC films completely free of double positioning boundaries and stacking faults on 4H-SiC and 6H-SiC substrate mesas. The process is based upon the initial 2-dimensional nucleation and lateral expansion of a single island of 3C-SiC on a 4H- or 6H-SiC mesa surface that is completely free of bilayer surface steps. Our experimental results indicate that substrate-epilayer in-plane lattice mismatch (Delta/a = 0.0854% for 3C/4H) is at least partially relieved parallel to the interface in the initial bilayers of the heterofilm, producing an at least partially relaxed 3C-SiC film without dislocations that undesirably thread through the thickness of the epilayer. This result should enable realization of improved 3C-SiC devices.

  3. Towards a more comprehensive usage of reflection seismic in near-surface characterization

    NASA Astrophysics Data System (ADS)

    Blouin, M.; Gloaguen, E.; Bellefleur, G.; Pugin, A.

    2014-12-01

    For more than a decade, research groups such as the Geological Survey of Canada built the interest for near-surface reflection seismic by proposing small vibrating sources and three components (3C) landstreamers. Developments in the instrumentation combined with extensive use of shear-wave profiling to image stratigraphy of unconsolidated environments at high resolution got this geophysical method more versatile, more accurate, increased cost effectiveness and allowed to cover greater distance per day. With those major upgrades as a starting point and in a context of regional aquifer characterization in St-Lawrence Lowlands in the province of Quebec, Canada, the present study propose a workflow to further enhance reflection seismic usage for near-surface characterization. First, as high resolution near surface surveys require small shot intervals and multiple channels on three axis, a lot of the acquisition information is received under a raw form yielding to unproductive quality control (QC). Hence, a tool was developed to process data "on the fly" and allow adequate real-time QC and on-site decision making. The algorithm was constructed in a Python environment and is accessible through a graphical user interface where the user is prompted for geometry parameters inputs and desired processing flow steps. Second, at the scale of seismic wavelengths, fine grain and poorly consolidated sediments such as marine clay of the St-Lawrence Lowlands can be viewed as a homogeneous medium presenting anisotropy. This section of the study showed that such geological settings yield to significant seismic velocity variations with angle of propagation that should not be ignore for normal move-out correction, migration or time to depth conversion. Finally, accurate delineation of stratigraphic horizons is an important task of any environmental or hydrogeological characterization study. A methodology was put forward to help integrate geophysical measurements with geological

  4. Estimation of Sea Surface Temperature (SST) Using Marine Seismic Data

    NASA Astrophysics Data System (ADS)

    Sinha, Satish Kumar; Dewangan, Pawan; Sain, Kalachand

    2016-04-01

    Not much attention is given to direct wave arrivals in marine seismic data that are acquired for petroleum exploration and prospecting. These direct arrivals are usually muted out in routine seismic data processing. In the present study, we process these direct arrivals to accurately estimate soundspeed in near-surface seawater and invert for sea surface temperature. The established empirical equation describing the relationships among temperature, salinity, pressure and soundspeed is used for the inversion. We also discuss processing techniques, such as first-break picking and cross-correlation for the estimation of soundspeed, that are well known among petroleum-industry geophysicists. The accuracy of the methods is directly linked to the data quality and signal processing. The novelty in our approach is in the data conditioning, which consists essentially of spectral balancing based on a wavelet transform that compensates for spherical spreading and increases the signal-to-noise ( S/ N) ratio. The 2D seismic data used in this paper are from the offshore Krishna-Godavari Basin east of India. We observe a significantly higher soundspeed of 1545 m/s for near-surface water than the commonly used value of ~1500 m/s. The estimated temperature (from velocity) is about 30 °C. Interestingly, the estimated temperature matches well with the temperature recorded in the CTD profile acquired in the study area during the month of May, the month corresponding to the acquisition of seismic data. Furthermore, the estimated temperatures during different times of data acquisition correlate well with the expected diurnal variation in temperature.

  5. IMPACT OF DIELECTRIC PARAMETERS ON THE REFLECTIVITY OF 3C-SiC WAFERS WITH A ROUGH SURFACE MORPHOLOGY IN THE RESTSTRAHLEN REGION

    SciTech Connect

    J.A.A. Engelbrecht; E. Janzén; A. Henry; I.J. van Rooyen

    2014-04-01

    A layer-on-substrate model is used to obtain the infrared reflectance for 3C-SiC with a rough surface morphology. The effect of varying dielectric parameters of the “damaged layer” on the observed reflectivity of the 3C-SiC in the reststrahlen region is assessed. Different simulated reflectance spectra are obtained to those if the dielectric parameters of the “substrate” were varied. Most notable changes in the shape of the simulated reststrahlen peak are observed for changes in the high frequency dielectric constant, the phonon damping constant, the phonon frequencies and “thickness” of damaged surface layer.

  6. Advantages of wet work for near-surface seismic reflection

    USGS Publications Warehouse

    Miller, R.D.; Markiewicz, R.D.; Rademacker, T.R.; Hopkins, R.; Rawcliffe, R.J.; Paquin, J.

    2007-01-01

    Benefits of shallow water settings (0.1 to 0.5 m) are pronounced on shallow, high-resolution seismic reflection images and, for examples discussed here, range from an order of magnitude increased signal-to-noise ratio to resolution potential elevated by more than 8 times. Overall data quality of high-resolution seismic reflection data at three sites notorious for poor near-surface reflection returns was improved by coupling the source and/or receivers to a well sorted and fully saturated surface. Half-period trace-to-trace static offsets evident in reflections from receivers planted into a creek bank were eliminated by moving the geophones to the base of a shallow creek at the toe of the bank. Reflections from a dipping bedrock were recorded with a dominant frequency approaching 1 KHz from hydrophones in 0.5 m of water at the toe of a dam using a hammer impact source. A tamper impacted by a dead blow hammer in a shallow (10-20 cm) deep creek produced reflections with a dominant frequency over 400 Hz at depths as shallow as 6 ms. ?? 2007 Society of Exploration Geophysicists.

  7. Spectrum analysis of seismic surface waves and its applications in seismic landmine detection.

    PubMed

    Alam, Mubashir; McClellan, James H; Scott, Waymond R

    2007-03-01

    In geophysics, spectrum analysis of surface waves (SASW) refers to a noninvasive method for soil characterization. However, the term spectrum analysis can be used in a wider sense to mean a method for determining and identifying various modes of seismic surface waves and their properties such as velocity, polarization, etc. Surface waves travel along the free boundary of a medium and can be easily detected with a transducer placed on the free surface of the boundary. A new method based on vector processing of space-time data obtained from an array of triaxial sensors is proposed to produce high-resolution, multimodal spectra from surface waves. Then individual modes can be identified in the spectrum and reconstructed in the space-time domain; also, reflected waves can be separated easily from forward waves in the spectrum domain. This new SASW method can be used for detecting and locating landmines by analyzing the reflected waves for resonance. Processing examples are presented for numerically generated data, experimental data collected in a laboratory setting, and field data.

  8. Regression modeling of finite field and anti-electromagnetic design for the ocean surface wind speed measurements of the FY-3C microwave imager

    NASA Astrophysics Data System (ADS)

    An, Dawei; Lu, Feng; Dou, Fangli; Zhang, Peng

    2014-11-01

    The purpose of this study is to select a suitable ocean wind inversion method for FY-3C (MWRI). Based on the traditional empirical model of sea surface wind speed inversion, and in the case of small sample size of FY-3C satellite load regression analysis, this paper analyzes the channel differences between the FY-3C satellite microwave radiation imager (MWRI) and TMI onboard the TRMM. The paper also analyzes the influence of these differences on the channel in terms of receiving temperature, including channel frequency f, sensitivity ΔK and scaling precision K. Then, the limited range of new model coefficient regression analysis is determined, the regression methods of the finite field are proposed, and the empirical model of wind speed inversion applicable to MWRI is obtained, The method corrected by 2014 FY3C observation data and buoy data, and then by anti-electromagnetic interference geostationary communications satellite designed to fit in the FY-3C (MWRI). which achieves strong results. Compared to the TAO buoy data, the RMS of the new model is 1.18 m/s. In addition, the schematic diagram of the global ocean surface wind speed inversion is provided.1

  9. Dust content of a hydrogen rich, low surface brightness galaxy and the luminosity history of 3C273

    NASA Technical Reports Server (NTRS)

    Hamilton, Thomas T.

    1993-01-01

    This project consists of a 30,000 second PSPC observation of the Giovanelli-Haynes Cloud in an attempt to detect light emitted by 3C273 which has been reflected by the cloud, and incidentally search the cloud for other sources of X-ray emission. The observation was carried out by ROSAT on Dec. 25, 1992 and the data was received by the P.I. in late March of 1993. We have examined the data and determined that the observation's background level, astrometry, etc. are acceptable. We have also detected diffuse emission from the direction of the Giovanelli-Haynes Cloud. Determination of the origin of this emission, by examining its morphology in relation to that of the radio map and the object's geometric relation with 3C273, requires software implementation of specialized algorithms. However, the most dramatic observation in the field is a potentially new population of discrete soft X-ray sources associated with dwarf galaxies.

  10. An integrated surface and borehole seismic case study: Fort St. John Graben area, Alberta, Canada

    SciTech Connect

    Hinds, R.C. . Dept. of Geology); Kuzmiski, R. ); Anderson, N.L. . Kansas Geological Survey); Richards, B.R. )

    1993-11-01

    The deltaic sandstones of the basal Kiskatinaw Formation (Stoddard Group, upper Mississippian) were preferentially deposited within structural lows in a regime characterized by faulting and structural lows in a regime characterized by faulting and structural subsidence. In the Fort St. John Graben area, northwest Alberta, Canada, these sandstone facies can form reservoirs where they are laterally sealed against the flanks of upthrown fault blocks. Exploration for basal Kiskatinaw reservoirs generally entails the acquisition and interpretation of surface seismic data prior to drilling. These data are used to map the grabens in which these sandstones were deposited, and the horst blocks which act as lateral seals. Subsequent to drilling, vertical seismic profile (VSP) surveys can be run. These data supplement the surface seismic and well log control in that: (1) VSP data can be directly correlated to surface seismic data. As a result, the surface seismic control can be accurately tied to the subsurface geology; (2) multiples, identified on VSP data, can be deconvolved out of the surface seismic data; and (3) the subsurface, in the vicinity of the borehole, is more clearly resolved on the VSP data than on surface seismic control. On the Fort St. John Graben data set incorporated into this paper, faults which are not well resolved on the surface seismic data, are better delineated on VSP data. The interpretative processing of these data illustrate the use of the seismic profiling technique in the search for hydrocarbons in structurally complex areas.

  11. Including Faults Detected By Near-Surface Seismic Methods in the USGS National Seismic Hazard Maps - Some Restrictions Apply

    NASA Astrophysics Data System (ADS)

    Williams, R. A.; Haller, K. M.

    2014-12-01

    Every 6 years, the USGS updates the National Seismic Hazard Maps (new version released July 2014) that are intended to help society reduce risk from earthquakes. These maps affect hundreds of billions of dollars in construction costs each year as they are used to develop seismic-design criteria of buildings, bridges, highways, railroads, and provide data for risk assessment that help determine insurance rates. Seismic source characterization, an essential component of hazard model development, ranges from detailed trench excavations across faults at the ground surface to less detailed analysis of broad regions defined mainly on the basis of historical seismicity. Though it is a priority for the USGS to discover new Quaternary fault sources, the discovered faults only become a part of the hazard model if there are corresponding constraints on their geometry (length and depth extent) and slip-rate (or recurrence interval). When combined with fault geometry and slip-rate constraints, near-surface seismic studies that detect young (Quaternary) faults have become important parts of the hazard source model. Examples of seismic imaging studies with significant hazard impact include the Southern Whidbey Island fault, Washington; Santa Monica fault, San Andreas fault, and Palos Verdes fault zone, California; and Commerce fault, Missouri. There are many more faults in the hazard model in the western U.S. than in the expansive region east of the Rocky Mountains due to the higher rate of tectonic deformation, frequent surface-rupturing earthquakes and, in some cases, lower erosion rates. However, the recent increase in earthquakes in the central U.S. has revealed previously unknown faults for which we need additional constraints before we can include them in the seismic hazard maps. Some of these new faults may be opportunities for seismic imaging studies to provide basic data on location, dip, style of faulting, and recurrence.

  12. A Bayesian framework for fracture characterization from surface seismic data

    NASA Astrophysics Data System (ADS)

    Zamanian, S. Ahmad; Fehler, Michael C.; Fang, Xinding; Burns, Daniel R.

    2014-11-01

    We describe a methodology for quantitatively characterizing the fractured nature of a hydrocarbon or geothermal reservoir from surface seismic data under a Bayesian inference framework. The method combines different kinds of measurements of fracture properties to find a best-fitting model while providing estimates of the uncertainty of model parameters. Fractures provide pathways for fluid flow in a reservoir, and hence, knowledge about a reservoir's fractured nature can be used to enhance production from the reservoir. The fracture properties of interest in this study (to be inferred) are fracture orientation and excess compliance, where each of these properties are assumed to vary spatially over a 2-D horizontal grid which is assumed to represent the top of a reservoir. The Bayesian framework in which the inference problem is cast has the key benefits of (1) utilization of a prior model that allows geological information to be incorporated, (2) providing a straightforward means of incorporating all measurements (across the 2-D spatial grid) into the estimates at each gridpoint, (3) allowing different types of measurements to be combined under a single inference procedure and (4) providing a measure of uncertainty in the estimates. The observed data are taken from a 2-D array of surface seismic receivers responding to an array of surface sources. Well understood features from the seismic traces are extracted and treated as the observed data, namely the P-wave reflection amplitude variation with acquisition azimuth and offset (amplitude versus azimuth data) and fracture transfer function (FTF) data. Amplitude versus azimuth data are known to be more sensitive to fracture properties when the fracture spacing is significantly smaller than the seismic wavelength, whereas FTF data are more sensitive to fracture properties when the fracture spacing is on the order of the seismic wavelength. Combining these two measurements has the benefit of allowing inferences to be

  13. Application of Surface-Wave Methods for Seismic Site Characterization

    NASA Astrophysics Data System (ADS)

    Foti, Sebastiano; Parolai, Stefano; Albarello, Dario; Picozzi, Matteo

    2011-11-01

    Surface-wave dispersion analysis is widely used in geophysics to infer a shear wave velocity model of the subsoil for a wide variety of applications. A shear-wave velocity model is obtained from the solution of an inverse problem based on the surface wave dispersive propagation in vertically heterogeneous media. The analysis can be based either on active source measurements or on seismic noise recordings. This paper discusses the most typical choices for collection and interpretation of experimental data, providing a state of the art on the different steps involved in surface wave surveys. In particular, the different strategies for processing experimental data and to solve the inverse problem are presented, along with their advantages and disadvantages. Also, some issues related to the characteristics of passive surface wave data and their use in H/V spectral ratio technique are discussed as additional information to be used independently or in conjunction with dispersion analysis. Finally, some recommendations for the use of surface wave methods are presented, while also outlining future trends in the research of this topic.

  14. Surface-Source Downhole Seismic Analysis in R

    USGS Publications Warehouse

    Thompson, Eric M.

    2007-01-01

    This report discusses a method for interpreting a layered slowness or velocity model from surface-source downhole seismic data originally presented by Boore (2003). I have implemented this method in the statistical computing language R (R Development Core Team, 2007), so that it is freely and easily available to researchers and practitioners that may find it useful. I originally applied an early version of these routines to seismic cone penetration test data (SCPT) to analyze the horizontal variability of shear-wave velocity within the sediments in the San Francisco Bay area (Thompson et al., 2006). A more recent version of these codes was used to analyze the influence of interface-selection and model assumptions on velocity/slowness estimates and the resulting differences in site amplification (Boore and Thompson, 2007). The R environment has many benefits for scientific and statistical computation; I have chosen R to disseminate these routines because it is versatile enough to program specialized routines, is highly interactive which aids in the analysis of data, and is freely and conveniently available to install on a wide variety of computer platforms. These scripts are useful for the interpretation of layered velocity models from surface-source downhole seismic data such as deep boreholes and SCPT data. The inputs are the travel-time data and the offset of the source at the surface. The travel-time arrivals for the P- and S-waves must already be picked from the original data. An option in the inversion is to include estimates of the standard deviation of the travel-time picks for a weighted inversion of the velocity profile. The standard deviation of each travel-time pick is defined relative to the standard deviation of the best pick in a profile and is based on the accuracy with which the travel-time measurement could be determined from the seismogram. The analysis of the travel-time data consists of two parts: the identification of layer-interfaces, and the

  15. Feasibility of using a seismic surface wave method to study seasonal and weather effects on shallow surface soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this paper is to study the feasibility of using a seismic surface wave method to investigate seasonal and weather effects on shallow surface soils. In the study, temporal variations of subsurface soil properties were measured and monitored by using a combination of a new seismic su...

  16. Air-ground interface: Surface waves, surface impedance and acoustic-to-seismic coupling coefficient

    NASA Technical Reports Server (NTRS)

    Daigle, Gilles; Embleton, Tony

    1990-01-01

    In atmospheric acoustics, the subject of surface waves has been an area of discussion for many years. The existence of an acoustic surface wave is now well established theoretically. The mathematical solution for spherical wave propagation above an impedance boundary includes the possibility of a contribution that possesses all the standard properties for a surface wave. Surface waves exist when the surface is sufficiently porous, relative to its acoustical resistance, that it can influence the airborne particle velocity near the surface and reduce the phase velocity of sound waves in air at the surface. This traps some of the sound energy in the air to remain near the surface as it propagates. Above porous grounds, the existence of surface waves has eluded direct experimental confirmation (pulse experiments have failed to show a separate arrival expected from the reduced phase speed) and indirect evidence for its existence has appeared contradictory. The experimental evidence for the existence of an acoustical surface wave above porous boundaries is reviewed. Recent measurements including pulse experiments are also described. A few years ago the acoustic impedance of a grass-covered surface was measured in the frequency range 30 to 300 Hz. Here, further measurements on the same site are discussed. These measurements include core samples, a shallow refractive survey to determine the seismic velocities, and measurements of the acoustic-to-seismic coupling coefficient.

  17. Control system for inclined impact-type surface seismic source

    SciTech Connect

    Karner, G.M.

    1987-07-28

    A system is described for controlling the azimuths and inclinations of the respective shooting paths of separate vehicle-transported surface seismic sources. Each source has an impact mass, means for propelling the mass along the shooting path to strike an earth contacting base plate, and means for adjusting each shooting path by rotation thereof about two mutually perpendicular gimbal axes oriented in predetermined relation to the heading of the associated vehicle. The system consists of: (a) means for determining each such vehicle heading; (b) means dependent upon each vehicle heading for calculating the angular positions of each shooting path with respect to the gimbal axes which align the shooting path with desired values of azimuth and inclination; and (c) means responsive to the calculation means for actuating each shooting path adjustment means to effect such alignment.

  18. Surface-contacting vibrometers for seismic landmine detection

    NASA Astrophysics Data System (ADS)

    Martin, James S.; Larson, Gregg D.; Scott, Waymond R., Jr.

    2005-06-01

    A technique has been developed that exploits remote seismic sources and local measurement of the surface displacement of the ground for the detection of buried landmines. Most of the previously reported investigation of this technique has focused on non-contact displacement sensors in order to ensure the safety of the operators of both handheld and vehicle-based systems. This is not inherently a constraint that requires a non-contact sensor, but rather one requiring a sensor that is non-intrusive (i.e. its presence does not alter the measured quantity). Current research is directed toward the development of autonomous and semi-autonomous robotic systems based on this technique. Here both unit cost and power consumption are issues of comparable importance to the survival of the sensor platform. Non-intrusive surface-contacting vibrometers are therefore a reasonable alternative. Several configurations have been studied for suitable vibrometers. The configuration that has shown the most promise is based on a commercial accelerometer coupled to the ground with a small normal force and isolated from the backing structure that is used to reposition it between measurements. It is a relatively simple matter to detect seismic motion with an accelerometer. The major issue in an effective implementation of the technique is to combine reproducibility with fidelity in the measurement. These are competing goals in that reproducibility is easily achieved with large normal forces, but fidelity requires that these be small. Sufficient reproducibility for imaging purposes has been achieved with normal forces that pose no danger of landmine detonation. Unlike reproducibility, fidelity is linked to both the nature of the imposed force and to its magnitude through the nonlinearity of the soil"s elasticity. Both continuous and incremental motions of the sensor platform have been studied, although incremental movement shows the most promise for the intended application.

  19. Military applications and examples of near-surface seismic surface wave methods (Invited)

    NASA Astrophysics Data System (ADS)

    sloan, S.; Stevens, R.

    2013-12-01

    Although not always widely known or publicized, the military uses a variety of geophysical methods for a wide range of applications--some that are already common practice in the industry while others are truly novel. Some of those applications include unexploded ordnance detection, general site characterization, anomaly detection, countering improvised explosive devices (IEDs), and security monitoring, to name a few. Techniques used may include, but are not limited to, ground penetrating radar, seismic, electrical, gravity, and electromagnetic methods. Seismic methods employed include surface wave analysis, refraction tomography, and high-resolution reflection methods. Although the military employs geophysical methods, that does not necessarily mean that those methods enable or support combat operations--often times they are being used for humanitarian applications within the military's area of operations to support local populations. The work presented here will focus on the applied use of seismic surface wave methods, including multichannel analysis of surface waves (MASW) and backscattered surface waves, often in conjunction with other methods such as refraction tomography or body-wave diffraction analysis. Multiple field examples will be shown, including explosives testing, tunnel detection, pre-construction site characterization, and cavity detection.

  20. Detailed study of the influence of surface misorientation on the density of Anti-Phase Boundaries in 3C-SiC layers grown on (001) silicon

    SciTech Connect

    Jiao, S.; Zielinski, M.; Chassagne, T.; Roy, S.; Michaud, J. F.; Alquier, D.; Portail, M.

    2010-11-01

    In this work we investigated the influence of the Si substrate misorientation and 3C-SiC film thickness on the density of Anti-Phase Boundaries, in order to better understand the mechanism of antiphase domain annihilation. The two highlights in our work are the utilization of [001] orientated Si on-axis wafer with spherical dimples, which gave us access to a continuum of off-cut angles (0 deg. to {approx}11 deg.) and directions, and the deposition of elongated silicon islands on the surface of 3C-SiC epilayers, which improved the detection of APDs by analysis of Scanning Electron Microscopy images. We found that for a given layer thickness the relative surface occupation of one domain increases with the off-cut angle value, leading to single domain film up to a certain angle. This critical value is reduced as the film is thickened.

  1. Ti3C2 MXenes with Modified Surface for High-Performance Electromagnetic Absorption and Shielding in the X-Band.

    PubMed

    Han, Meikang; Yin, Xiaowei; Wu, Heng; Hou, Zexin; Song, Changqing; Li, Xinliang; Zhang, Litong; Cheng, Laifei

    2016-08-17

    Electromagnetic (EM) absorbing and shielding composites with tunable absorbing behaviors based on Ti3C2 MXenes are fabricated via HF etching and annealing treatment. Localized sandwich structure without sacrificing the original layered morphology is realized, which is responsible for the enhancement of EM absorbing capability in the X-band. The composite with 50 wt % annealed MXenes exhibits a minimum reflection loss of -48.4 dB at 11.6 GHz, because of the formation of TiO2 nanocrystals and amorphous carbon. Moreover, superior shielding effectiveness with high absorption effectiveness is achieved. The total and absorbing shielding effectiveness of Ti3C2 MXenes in a wax matrix with a thickness of only 1 mm reach values of 76.1 and 67.3 dB, while those of annealed Ti3C2 MXenes/wax composites are 32 and 24.2 dB, respectively. Considering the promising performance of Ti3C2 MXenes with the modified surface, this work is expected to open the door for the expanded applications of MXenes family in EM absorbing and shielding fields. PMID:27454148

  2. High resolution seismic imaging of Rainier Mesa using surface reflection and surface to tunnel tomography

    SciTech Connect

    Majer, E.L.; Johnson, L.R.; Karageorgi, E.K.; Peterson, J.E.

    1994-06-01

    In the interpretation of seismic data to infer properties of an explosion source, it is necessary to account for wave propagation effects. In order to understand and remove these propagation effects, it is necessary to have a model. An open question concerning this matter is the detail and accuracy which must be present in the velocity model in order to produce reliable estimates in the estimated source properties. While it would appear that the reliability of the results would be directly related to the accuracy of the velocity and density models used in the interpretation, it may be that certain deficiencies in these models can be compensated by the and amount of seismic data which is used in the inversion. The NPE provided an opportunity to test questions of this sort. In August 1993, two high resolution seismic experiments were performed in N-Tunnel and on the surface of Rainier Mesa above it. The first involved a surface-to-tunnel imaging experiment with sources on the surface and receivers in tunnel U12n.23 about 88 meters west of the NPE. It was possible to estimate the apparent average velocity between the tunnel and the surface. In a separate experiment, a high resolution reflection experiment was performed in order to image the lithology in Rainier Mesa. Good quality, broad band, reflections were obtained from depths extending into the Paleozoic basement. A high velocity layer near the surface is underlain by a thick section of low velocity material, providing a nonuniform but low average velocity between the depth of the NPE and the surface.

  3. The fabrication of stable superhydrophobic surfaces using a thin Au/Pd coating over a hydrophilic 3C-SiC nanorod network

    NASA Astrophysics Data System (ADS)

    Khan, Afzal; Sohail, Shiraz; Jacob, Chacko

    2015-10-01

    In this work, it has been demonstrated that for hydrophilic materials, like SiC, etc., superhydrophobicity can be achieved by coating them with a material like Au/Pd with surface adsorbed organic contaminants, rather than modifying them by fluoropolymers as is usually done. Dense and randomly aligned 3C-SiC nanorods were grown in a cold-wall APCVD reactor using Ni as a catalyst which formed a network of micro/nano air pockets and exhibited superhydrophobic behavior when modified by an Au/Pd metal alloy coating by forming hierarchical nanostructures with surface adsorbed organic contaminants. A high water contact angle (160°), very low sliding angle (<5°), rebounding and a rubber ball-like behavior of a water droplet were observed on such a metal (Au/Pd) modified surface of 3C-SiC nanorods. The durability of the surface and reproducibility of the results was checked over a period of about 14 months under ambient atmosphere at room temperature, which demonstrates the long term stability of these superhydrophobic surfaces.

  4. Development of near surface seismic methods for urban and mining applications

    NASA Astrophysics Data System (ADS)

    Malehmir, Alireza; Brodic, Bojan; Place, Joachim; Juhlin, Christopher; Bastani, Mehrdad

    2014-05-01

    There is a great need to improve our understanding of the geological conditions in the shallow subsurface. Direct observations of the subsurface are cumbersome and expensive, and sometimes impossible. Urban and mining areas are especially challenging due to various sources of noise such as from traffic, buildings, cars, city trains, trams, bridges and high-voltage power-lines. Access is also restricted both in time and space, which requires the equipment to be versatile, fast to set up and pack, and produces the least disruptions. However, if properly designed and implemented, geophysical methods are capable of imaging detailed subsurface structures and can successfully be used to provide crucial information for site characterizations, infrastructure planning, brown- and near-field exploration, and mine planning. To address some of these issues Uppsala University, in collaboration with a number of public authorities, research organizations and industry partners, has recently developed a prototype broadband (0-800 Hz based on digital sensors) multi-component seismic landstreamer system. The current configuration consists of three segments with twenty 3C-sensors each 2 m apart and an additional segment with twenty 3C-sensors each 4 m apart, giving a total streamer length of 200 m. These four segments can be towed in parallel or in series, which in combination with synchronized wireless and cabled sensors can address a variety of complex near surface problems. The system is especially geared for noisy environments and areas where high-resolution images of the subsurface are needed. The system has little sensitivity to electrical noise and measures sensor tilt, important in rough terrains, so it can immediately be corrected for during the acquisition. Thanks to the digital sensors, the system can also be used for waveform tomography and multi-channel analysis of surface waves (MASW). Both these methods require low frequencies and these are often sacrificed in

  5. Dense Seismic Recordings of Two Surface-Detonated Chemical Explosions

    NASA Astrophysics Data System (ADS)

    Koper, K. D.; Hale, J. M.; Burlacu, R.; Goddard, K. J.; Trow, A.; Linville, L. M.; Stein, J. R.; Drobeck, D.; Leidig, M.

    2015-12-01

    In the summer of 2015 two controlled chemical explosions were carried out near Dugway, Utah. The 2 June 2015 explosion consisted of 30,000 lbs of ammonium nitrate fuel oil (ANFO) and the 22 July 2015 explosion consisted of 60,000 lbs of ANFO. The explosion centroids were 1-2 m above the Earth's surface and both created significant craters in the soft desert alluvium. To better understand the seismic source associated with surface explosions, we deployed an array of wireless, three-component, short-period (5 Hz corner frequency) seismometers for several days around each shot. For the first explosion, 46 receivers were deployed in a "lollipop" geometry that had a sparse ring at a radius of 1 km, and a dense stem with 100 m spacing for distances of 0.5-4.5 km. For the second explosion, 48 receivers were deployed similarly, but with a dense ring spaced in azimuthal increments of 10 degrees at a distance of 1 km, and a sparse stem (~500 m spacing) that extended to a distance of nearly 6 km. A rich variety of phases were recorded including direct P waves, refracted and reflected P waves, nearly monochromatic air-coupled Rayleigh waves, normally dispersed fundamental mode Rayleigh waves (Rg), primary airblast arrivals, some secondary airblast arrivals, and possibly tertiary airblast arrivals. There is also evidence of converted S waves on the radial components and possibly direct S energy on the radial and transverse components, although the transverse energy does not always possess a simple, coherent move-out with distance, implying that it might have a scattering origin. To aid in the phase identification, especially of the apparent SH and Love energy, we are currently performing tau-p, f-k, and particle motion analysis.

  6. Soil Surface Seismic Hazard and Design Basis Guideline for PC 1 and 2 SRS Facilities

    SciTech Connect

    Lee, R.C.

    2000-04-26

    This report describes the development of Savannah River Site (SRS) soil seismic hazard for oscillator frequencies of 1, 2, 5, and 10 Hz. This soil surface hazard supersedes all previous soil hazard analyses conducted for the SRS.

  7. Seismic Technology Adapted to Analyzing and Developing Geothermal Systems Below Surface-Exposed High-Velocity Rocks Final Report

    SciTech Connect

    Hardage, Bob A.; DeAngelo, Michael V.; Ermolaeva, Elena; Hardage, Bob A.; Remington, Randy; Sava, Diana; Wagner, Donald; Wei, Shuijion

    2013-02-01

    applications by inserting into this report a small part of the interpretation we have done with 3C3D data across Wister geothermal field in the Imperial Valley of California. This interpretation shows that P-SV data reveal faults (and by inference, also fractures) that cannot be easily, or confidently, seen with P-P data, and that the combination of P-P and P-SV data allows VP/VS velocity ratios to be estimated across a targeted reservoir interval to show where an interval has more sandstone (the preferred reservoir facies). The conclusion reached from this investigation is that S-wave seismic technology can be invaluable to geothermal operators. Thus we developed a strong interest in understanding the direct-S modes produced by vertical-force sources, particularly vertical vibrators, because if it can be demonstrated that direct-S modes produced by vertical-force sources can be used as effectively as the direct-S modes produced by horizontal-force sources, geothermal operators can acquire direct-S data across many more prospect areas than can be done with horizontal-force sources, which presently are limited to horizontal vibrators. We include some of our preliminary work in evaluating direct-S modes produced by vertical-force sources.

  8. Seismic signatures of carbonate caves affected by near-surface absorptions

    NASA Astrophysics Data System (ADS)

    Rao, Ying; Wang, Yanghua

    2015-12-01

    The near-surface absorption within a low-velocity zone generally has an exponential attenuation effect on seismic waves. But how does this absorption affect seismic signatures of karstic caves in deep carbonate reservoirs? Seismic simulation and analysis reveals that, although this near-surface absorption attenuates the wave energy of a continuous reflection, it does not alter the basic kinematic shape of bead-string reflections, a special seismic characteristic associated with carbonate caves in the Tarim Basin, China. Therefore, the bead-strings in seismic profiles can be utilized, with a great certainty, for interpreting the existence of caves within the deep carbonate reservoirs and for evaluating their pore spaces. Nevertheless, the difference between the central frequency and the peak frequency is increased along with the increment in the absorption. While the wave energy of bead-string reflections remains strong, due to the interference of seismic multiples generated by big impedance contrast between the infill materials of a cave and the surrounding carbonate rocks, the central frequency is shifted linearly with respect to the near-surface absorption. These two features can be exploited simultaneously, for a stable attenuation analysis of field seismic data.

  9. Step Free Surface Heteroepitaxy of 3C-SiC Layers on Patterned 4H/6H-SiC Mesas and Cantilevers

    NASA Technical Reports Server (NTRS)

    Neudeck, Philip G.; Powell, J. Anthony; Trunek, Andrew J.; Spry, David J.

    2003-01-01

    Most SiC devices are implemented in homoepitaxial films grown on 4H/6H-SiC wafers with surfaces 3 degrees to 8 degrees off-axis from the (0001) basal plane. This approach has not prevented many substrate crystal defects from propagating into SiC epilayers, and does not permit the realization of SiC heteropolytype devices. This presentation describes recent advances in SiC epitaxial growth that begun to overcome the above shortcomings for arrays of mesas patterned into on-axis 4H/6H-SiC wafers. First, we demonstrated that atomic-scale surface steps can be completely eliminated from 4H/6H-SiC mesas via on-axis homoepitaxial step-flow growth, forming (0001) basal plane surfaces (up to 0.4 mm x 0.4 mm) for larger than previously thought possible. Step-free surface areas were then extended by growth fo thin lateral cantilevers from the mesa tops. These lateral cantilevers enabled substrate defects to be reduced and relocated in homoepitaxial films in a manner not possible with off-axis SiC growth. Finally, growth of vastly improved 3C-SiC heterofilms was achieved on 4H/6H-SiC mesas using the recently develop step-free surface heteroepitaxy process. These epitaxial growth developments should enable improved homojunction and heterojunction silicon carbide prototype devices.

  10. Microseismic Monitoring Using Surface and Borehole Seismic Stations in an Oil Field, North Oman

    NASA Astrophysics Data System (ADS)

    El-Hussain, I.; Al-Hashmi, S.; Al-Shijbi, Y.; Al-Saifi, M.; Al-Toubi, K.; Al-Lazki, A.; Al-Kindy, F.

    2009-05-01

    Five shallow borehole seismic stations were installed to monitor microearthquake activities in a carbonate oil field in northern Oman since 1999. This shallow network of seismic station operated continuously until 2002 after which intermittent seismic recording took place due to lack of maintenance and failure of some stations. The objectives of the study are to determine the microseismic parameters in the oil field and to determine the spatial and temporal distribution of these events to evaluate possible triggering mechanism. Well over 400 microearthquakes per year were recorded in the first three years of operation and after that the level of seismic recording fell to less than 200 microearthquakes per year due to failure of some stations. In March 2008, temporary seismic experiment consisting of five near surface seismic stations were installed in the oil field to augment the shallow network station and to evaluate surface installment of seismic instrument to monitor microseismic activities. It has been recognized that microearthquakes data such as size, spatial, and temporal distribution provide information on the pressure waves initiated by either production of or injection of fluids into reservoirs. A total of 44 local microearthquake events were analyzed and located during the temporary seismic stations deployment using a non-linear location software that allows the use of variable accurate velocity model of the subsurface. The events location is confined to oil field reservoir boundary during the recording period and more events occurring at shallow depth. The correlation coefficient between gas production and number of events is the higher compared with the oil production or water injection. The focal plane solution for the largest event in the sequence indicates normal faulting with extensional stress consistent with the existing mapped normal faults in the oil field. Microseismic signal clearly detected by the collocated sensors of the near surface

  11. Near-surface velocity structure from borehole and refraction seismic surveys

    SciTech Connect

    Parry, D.; Lawton, D.C.

    1994-12-31

    Seismic refraction and borehole reflection data have been used in conjunction with other geophysical tools to characterize the near-surface geology in the vicinity of a shallow well near Calgary, Alberta. The investigated section is comprised primarily of glacial tills and gravels. Seismic waves generated in the lower gravel units travel as compressional waves up to the till/gravel interface, where they are converted to shear waves upon transmission. Velocity structure from a reverse vertical seismic profile (RVSP) survey agrees closely with that from refraction surveying.

  12. Lunar seismic profiling experiment. [Apollo 17 flight measurements of lunar surface vibrations to determine subsurface characteristics

    NASA Technical Reports Server (NTRS)

    Kovach, R. L.; Watkins, J. S.; Talwani, P.

    1973-01-01

    The Apollo 17 lunar seismic profiling experiment was conducted to record the vibrations of the lunar surface as induced by explosive charges, the thrust of the lunar module ascent engine, and the crash of the lunar module ascent stage. Analysis of the data obtained made it possible to determine the internal characteristics of the lunar crust to a depth of several kilometers. The test equipment used in the experiment is described. Maps showing the location of the geophones and the deployed explosive packages are provided. Samples of the seismic signals recorded by the lunar seismic profiling experiment geophones are included.

  13. Feasibility of using a seismic surface wave method to study seasonal and weather effects on shallow surface soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of the paper is to study the temporal variations of the subsurface soil properties due to seasonal and weather effects using a combination of a new seismic surface method and an existing acoustic probe system. A laser Doppler vibrometer (LDV) based multi-channel analysis of surface wav...

  14. Seismic reading taken at MSC recording impact of Apollo 13 S-IVB with surface

    NASA Technical Reports Server (NTRS)

    1970-01-01

    A seismic reading taken from instruments at the Manned Spacecraft Center (MSC) recording impact of the Apollo 13 S-IVB/Instrument Unit with lunar surface. The expended Saturn third stage and instrument unit impacted the lunar surface at 7:09 p.m., April 14, 1970. The location of the impact was 2.4 degrees south latitude and 27.9 degrees west longitude, about 76 nautical miles west-northwest of the Apollo 12 Lunar Surface Experiment package deployment site. The S-IVB/IU impact was picked up by the Passive Seismic Experiment, a component of the package and transmitted to instruments at the Mission Control Center.

  15. Characterization of a complex near-surface structure using well logging and passive seismic measurements

    NASA Astrophysics Data System (ADS)

    Benjumea, Beatriz; Macau, Albert; Gabàs, Anna; Figueras, Sara

    2016-04-01

    We combine geophysical well logging and passive seismic measurements to characterize the near-surface geology of an area located in Hontomin, Burgos (Spain). This area has some near-surface challenges for a geophysical study. The irregular topography is characterized by limestone outcrops and unconsolidated sediments areas. Additionally, the near-surface geology includes an upper layer of pure limestones overlying marly limestones and marls (Upper Cretaceous). These materials lie on top of Low Cretaceous siliciclastic sediments (sandstones, clays, gravels). In any case, a layer with reduced velocity is expected. The geophysical data sets used in this study include sonic and gamma-ray logs at two boreholes and passive seismic measurements: three arrays and 224 seismic stations for applying the horizontal-to-vertical amplitude spectra ratio method (H/V). Well-logging data define two significant changes in the P-wave-velocity log within the Upper Cretaceous layer and one more at the Upper to Lower Cretaceous contact. This technique has also been used for refining the geological interpretation. The passive seismic measurements provide a map of sediment thickness with a maximum of around 40 m and shear-wave velocity profiles from the array technique. A comparison between seismic velocity coming from well logging and array measurements defines the resolution limits of the passive seismic techniques and helps it to be interpreted. This study shows how these low-cost techniques can provide useful information about near-surface complexity that could be used for designing a geophysical field survey or for seismic processing steps such as statics or imaging.

  16. A new impulsive seismic shear wave source for near-surface (0-30 m) seismic studies

    NASA Astrophysics Data System (ADS)

    Crane, J. M.; Lorenzo, J. M.

    2010-12-01

    Estimates of elastic moduli and fluid content in shallow (0-30 m) natural soils below artificial flood containment structures can be particularly useful in levee monitoring as well as seismic hazard studies. Shear wave moduli may be estimated from horizontally polarized, shear wave experiments. However, long profiles (>10 km) with dense receiver and shot spacings (<1m) cannot be collected efficiently using currently available shear wave sources. We develop a new, inexpensive, shear wave source for collecting fast, shot gathers over large acquisition sites. In particular, gas-charged, organic-rich sediments comprising most lower-delta sedimentary facies, greatly attenuate compressional body-waves. On the other hand, SH waves are relatively insensitive to pore-fluid moduli and can improve resolution. We develop a recoil device (Jolly, 1956) into a single-user, light-weight (<20 kg), impulsive, ground-surface-coupled SH wave generator, which is capable of working at rates of several hundred shotpoints per day. Older impulsive methods rely on hammer blows to ground-planted stationary targets. Our source is coupled to the ground with steel spikes and the powder charge can be detonated mechanically or electronically. Electrical fuses show repeatability in start times of < 50 microseconds. The barrel and shell-holder exceed required thicknesses to ensure complete safety during use. The breach confines a black-powder, 12-gauge shotgun shell, loaded with inert, environmentally safe ballast. In urban settings, produced heat and sound are confined by a detached, exterior cover. A moderate 2.5 g black-powder charge generates seismic amplitudes equivalent to three 4-kg sledge-hammer blows. We test this device to elucidate near subsurface sediment properties at former levee breach sites in New Orleans, Louisiana, USA. Our radio-telemetric seismic acquisition system uses an in-house landstreamer, consisting of 14-Hz horizontal component geophones, coupled to steel plates

  17. Cable development for distributed geophysical sensing with a field trial in surface seismic

    NASA Astrophysics Data System (ADS)

    Lumens, Paul; Franzen, Andre; Hornman, Kees; Grandi Karam, Samantha; Hemink, Gijs; Kuvshinov, Boris; La Follett, Jon; Wyker, Brendan; Zwartjes, Paul

    2013-05-01

    Fibre-optic distributed sensing has the potential to revolutionize well and reservoir surveillance in the oil and gas industry. Benefits include the passive nature of optical fibre sensors, the potential for cost-effective installations, combined with the possibility of densely distributed measurements along the entire length of the fibre. Amongst a range of fibre-optic sensing technologies, Distributed Acoustic Sensing has the potential to provide a low cost alternative for conventional seismic technologies. To widen the geophysical application scope further, the fibre-optic sensing cable should be made more sensitive to incoming seismic waves that arrive at the cable perpendicular ("broadside") to its axial direction. We introduce the development of such cable concepts, and present results of a successful cable deployment in a surface seismic field trial. Efforts continue to realize cost-effective directionally-sensitive cables for geophysical use, for deployment down-hole and on surface.

  18. Passive monitoring for near surface void detection using traffic as a seismic source

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Kuzma, H. A.; Rector, J.; Nazari, S.

    2009-12-01

    In this poster we present preliminary results based on our several field experiments in which we study seismic detection of voids using a passive array of surface geophones. The source of seismic excitation is vehicle traffic on nearby roads, which we model as a continuous line source of seismic energy. Our passive seismic technique is based on cross-correlation of surface wave fields and studying the resulting power spectra, looking for "shadows" caused by the scattering effect of a void. High frequency noise masks this effect in the time domain, so it is difficult to see on conventional traces. Our technique does not rely on phase distortions caused by small voids because they are generally too tiny to measure. Unlike traditional impulsive seismic sources which generate highly coherent broadband signals, perfect for resolving phase but too weak for resolving amplitude, vehicle traffic affords a high power signal a frequency range which is optimal for finding shallow structures. Our technique results in clear detections of an abandoned railroad tunnel and a septic tank. The ultimate goal of this project is to develop a technology for the simultaneous imaging of shallow underground structures and traffic monitoring near these structures.

  19. High-resolution seismic reflection survey near SPR surface collapse feature at Weeks Island, Louisiana

    SciTech Connect

    Miller, R.D.; Xia, J.; Harding, R.S. Jr.; Steeples, D.W.

    1994-12-31

    Shallow high resolution 2-D and 3-D seismic reflection techniques are assisting in the subsurface delineation of a surface collapse feature (sinkhole) at Weeks Island, Louisiana. Seismic reflection surveys were conducted in March 1994. Data from walkaway noise tests were used to assist selection of field recording parameters. The top of the salt dome is about 180 ft below ground surface at the sinkhole. The water table is an estimated 90 ft below the ground surface. A single coherent reflection was consistently recorded across the entire area of the survey, although stacking velocity and spectral content of the event varied. On the basis of observed travel times and stacking velocities, the coherent reflection event appears to originate above the top of the salt, possibly at or near the water table. Identification of this reflector will be made form borehole investigations currently planned for the sinkhole site. A depression or time sag in this reflection event is clearly evident in both the 2-D and 3-D seismic data in the immediate vicinity of the sinkhole. The time sag appears to be related to the subsurface structure of the reflector and not to near surface topography or velocity effects. Elsewhere in the survey area, observed changes in reflection travel times and wavelet character appear to be related to subsurface geologic structure. These seismic observations may assist in predicting where future sinkholes will develop after they have been tied to borehole data collected at the site.

  20. Frequency-dependent traveltime tomography using fat rays: application to near-surface seismic imaging

    NASA Astrophysics Data System (ADS)

    Jordi, Claudio; Schmelzbach, Cedric; Greenhalgh, Stewart

    2016-08-01

    Frequency-dependent traveltime tomography does not rely on the high frequency assumption made in classical ray-based tomography. By incorporating the effects of velocity structures in the first Fresnel volume around the central ray, it offers a more realistic and accurate representation of the actual physics of seismic wave propagation and thus, enhanced imaging of near-surface structures is expected. The objective of this work was to apply frequency-dependent first arrival traveltime tomography to surface seismic data that were acquired for exploration scale and near-surface seismic imaging. We adapted a fat ray tomography algorithm from global-earth seismology that calculates the Fresnel volumes based on source and receiver (adjoint source) traveltime fields. The fat ray tomography algorithm was tested on synthetic model data that mimics the dimensions of two field data sets. The field data sets are presented as two case studies where fat ray tomography was applied for near-surface seismic imaging. The data set of the first case study was recorded for high-resolution near-surface imaging of a Quaternary valley (profile length < 1 km); the second data set was acquired for hydrocarbon search (profile length > 10 km). All results of fat ray tomography are compared against the results of classical ray-based tomography. We show that fat ray tomography can provide enhanced tomograms and that it is possible to recover more information on the subsurface when compared to ray tomography. However, model assessment based on the column sum of the Jacobian matrix revealed that especially the deep parts of the structure in the fat ray tomograms might not be adequately covered by fat rays. Furthermore, the performance of the fat ray tomography depends on the chosen input frequency in relation to the scale of the seismic survey. Synthetic data testing revealed that the best results were obtained when the frequency was chosen to correspond to an approximate wavelength

  1. Near-surface neotectonic deformation associated with seismicity in the northeastern United States

    SciTech Connect

    Alexander, S.S.; Gold, D.P.; Gardner, T.W.; Slingerland, R.L.; Thornton, C.P. . Dept. of Geosciences)

    1989-10-01

    For the Lancaster, PA seismic zone a multifaceted investigation revealed several manifestations of near-surface, neotectonic deformation. Remote sensing data together with surface geological and geophysical observations, and recent seismicity reveal that the neotectonic deformation is concentrated in a NS-trending fault zone some 50 km in length and 10--20 km in width. Anomalies associated with this zone include distinctive lineament and surface erosional patterns; geologically recent uplift evidenced by elevations of stream terraces along the Susquehanna River; and localized contemporary travertine deposits in streams down-drainage from the inferred active fault zone. In the Moodus seismic zone the frequency of tectonically-controlled lineaments was observed to increase in the Moodus quadrangle compared to adjacent areas and dominant lineament directions were observed that are perpendicular and parallel to the orientation of the maximum horizontal stress direction (N80-85E) recently determined from in-situ stress measurements in a 1.5 km-deep borehole in the seismic zone and from well-constrained earthquake focal mechanisms. 284 refs., 33 figs.

  2. Surface seismic measurements of near-surface P-and S-wave seismic velocities at earthquake recording stations, Seattle, Washington

    USGS Publications Warehouse

    Williams, R.A.; Stephenson, W.J.; Frankel, A.D.; Odum, J.K.

    1999-01-01

    We measured P-and S-wave seismic velocities to about 40-m depth using seismic-refraction/reflection data on the ground surface at 13 sites in the Seattle, Washington, urban area, where portable digital seismographs recently recorded earthquakes. Sites with the lowest measured Vs correlate with highest ground motion amplification. These sites, such as at Harbor Island and in the Duwamish River industrial area (DRIA) south of the Kingdome, have an average Vs in the upper 30 m (V??s30) of 150 to 170 m/s. These values of V??s30 place these sites in soil profile type E (V??s30 < 180 m/s). A "rock" site, located at Seward Park on Tertiary sedimentary deposits, has a V??S30 of 433 m/s, which is soil type C (V??s30: 360 to 760 m/s). The Seward Park site V??s30 is about equal to, or up to 200 m/s slower than sites that were located on till or glacial outwash. High-amplitude P-and S-wave seismic reflections at several locations appear to correspond to strong resonances observed in earthquake spectra. An S-wave reflector at the Kingdome at about 17 to 22 m depth probably causes strong 2-Hz resonance that is observed in the earthquake data near the Kingdome.

  3. Combined analysis of surface reflection imaging and vertical seismic profiling at Yucca Mountain, Nevada

    SciTech Connect

    Daley, T.M.; Majer, E.L.; Karageorgi, E.

    1994-08-01

    This report presents results from surface and borehole seismic profiling performed by the Lawrence Berkeley Laboratory (LBL) on Yucca Mountain. This work was performed as part of the site characterization effort for the potential high-level nuclear waste repository. Their objective was to provide seismic imaging from the near surface (200 to 300 ft. depth) to the repository horizon and below, if possible. Among the issues addressed by this seismic imaging work are location and depth of fracturing and faulting, geologic identification of reflecting horizons, and spatial continuity of reflecting horizons. The authors believe their results are generally positive, with tome specific successes. This was the first attempt at this scale using modem seismic imaging techniques to determine geologic features on Yucca Mountain. The principle purpose of this report is to present the interpretation of the seismic reflection section in a geologic context. Three surface reflection profiles were acquired and processed as part of this study. Because of environmental concerns, all three lines were on preexisting roads. Line 1 crossed the mapped surface trace of the Ghost Dance fault and it was intended to study the dip and depth extent of the fault system. Line 2 was acquired along Drill Hole wash and was intended to help the ESF north ramp design activities. Line 3 was acquired along Yucca Crest and was designed to image geologic horizons which were thought to be less faulted along the ridge. Unfortunately, line 3 proved to have poor data quality, in part because of winds, poor field conditions and limited time. Their processing and interpretation efforts were focused on lines 1 and 2 and their associated VSP studies.

  4. Fracture Detection in Alluvial Fan Deposits Using Near-Surface Seismic Reflection Techniques

    NASA Astrophysics Data System (ADS)

    Black, R. A.; Miller, B.

    2012-12-01

    In this study we document the observation of probable extensive shallow vertical fracture systems in unprocessed 2-D source gathers from near-surface seismic reflection surveys conducted over unconsolidated materials in alluvial fans environments. Mapping of fracture and fault systems within the sedimentary sections at hydrocarbon exploration scales has become common practice. This is due to the advent of post-stack attribute analysis of 3-D seismic images worldwide. However, examples of fracture detection and imaging in the near-surface are currently lacking in the literature. In addition, examples of fracture detection and mapping in the pre-stack domain are also lacking. In this study, unprocessed seismic source gathers from very high-resolution reflection surveys over alluvial fan deposits in tectonically active areas appear to display distinct patterns of amplitude drop off, geometrically similar to patterns expected for vertical fracture systems. The patterns can also be extracted by attribute analysis using techniques such as envelope and coherency analyses. Simple standard processing steps such as trace editing, muting, and bandpass filtering enhance interpretability. The patterns appear to be consistent and spatially fixed in the subsurface from source location to source location. These are observed in areas of obvious recent local large-scale fault movement. Examples are given from two areas, eastern Queen Valley in California and eastern Fish Lake Valley in Nevada. The stratigraphic and sedimentation patterns are quite complicated in both areas, and sediment characteristics vary considerably between sites. The surface sediments in the Queen Valley case are, in general, much coarser with many more boulder-sized clasts in the shallow subsurface. The seismic source consisted of a 30-06 rifle fired downhole at a depth of 0.5m. While the boulders interfered with seismic source operations, the record quality was excellent. The alluvial materials, especially

  5. Detection, location, and analysis of earthquakes using seismic surface waves (Beno Gutenberg Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Ekström, Göran

    2015-04-01

    For shallow sources, Love and Rayleigh waves are the largest seismic phases recorded at teleseismic distances. The utility of these waves for earthquake characterization was traditionally limited to magnitude estimation, since geographically variable dispersion makes it difficult to determine useful travel-time information from the waveforms. Path delays due to heterogeneity of several tens of seconds are typical for waves at 50 sec period, and these delays must be accounted for with precision and accuracy in order to extract propagation-phase and source-phase information. Advances in tomographic mapping of global surface-wave phase velocities, and continuous growth and improvements of seismographic networks around the world, now make possible new applications of surface waves for earthquake monitoring and analysis. Through continuous back propagation of the long-period seismic wave field recorded by globally distributed stations, nearly all shallow earthquakes greater than M=5 can be detected and located with a precision of 25 km. Some of the detected events do not appear in standard earthquake catalogs and correspond to non-tectonic earthquakes, including landslides, glacier calving, and volcanic events. With the improved ability to predict complex propagation effects of surface waves across a heterogeneous Earth, moment-tensor and force representations of seismic sources can be routinely determined for all earthquakes greater than M=5 by waveform fitting of surface waves. A current area of progress in the use of surface waves for earthquake studies is the determination of precise relative locations of remote seismicity by systematic cross correlation and analysis of surface waves generated by neighboring sources. Preliminary results indicate that a location precision of 5 km may be achievable in many areas of the world.

  6. Seismicity on the western Greenland Ice Sheet: Surface fracture in the vicinity of active moulins

    SciTech Connect

    Carmichael, Joshua D.; Joughin, Ian; Behn, Mark D.; Das, Sarah; King, Matt A.; Stevens, Laura; Lizarralde, Dan

    2015-06-25

    We analyzed geophone and GPS measurements collected within the ablation zone of the western Greenland Ice Sheet during a ~35 day period of the 2011 melt season to study changes in ice deformation before, during, and after a supraglacial lake drainage event. During rapid lake drainage, ice flow speeds increased to ~400% of winter values, and icequake activity peaked. At times >7 days after drainage, this seismicity developed variability over both diurnal and longer periods (~10 days), while coincident ice speeds fell to ~150% of winter values and showed nightly peaks in spatial variability. Approximately 95% of all detected seismicity in the lake basin and its immediate vicinity was triggered by fracture propagation within near-surface ice (<330 m deep) that generated Rayleigh waves. Icequakes occurring before and during drainage frequently were collocated with the down flow (west) end of the primary hydrofracture through which the lake drained but shifted farther west and outside the lake basin after the drainage. We interpret these results to reveal vertical hydrofracture opening and local uplift during the drainage, followed by enhanced seismicity and ice flow on the downstream side of the lake basin. This region collocates with interferometric synthetic aperture radar-measured speedup in previous years and could reflect the migration path of the meltwater supplied to the bed by the lake. The diurnal seismic signal can be associated with nightly reductions in surface melt input that increase effective basal pressure and traction, thereby promoting elevated strain in the surficial ice.

  7. Inversion of the Chelyabinsk seismic surface waves and comparative constraints on the generation of seismic waves by atmospheric Impacts on Earth and Mars

    NASA Astrophysics Data System (ADS)

    Karakostas, F. G.; Rakoto, V.; Lognonne, P. H.

    2015-12-01

    Meteor impacts are a very important seismic source for planetary seismology, since their locations and, in some cases, their occurence times can be accurately known from orbiters, tracking or optical observations. Their importance becomes greater in the case of a seismic experiment with one seismometer, as the SEIS (Seismic Experiment of Interior Structure) of the future Martian mission "InSight", as the known location allows a direct inversion of differential travel times and wave forms in terms of structure. Meteor impacts generate body and surface seismic waves when they reach the surface of a planet. But when they explode into the atmosphere, due to ablation, they generate shock waves, which are converted into linear, seismic waves in the solid part and acoustic waves in the atmosphere. This effect can be modeled when the amplitude of Rayleigh and other Spheroidal normal modes is made with the atmospheric/ground coupling effects. In this study, meteor impacts are modeled as seismic sources in a comparative analysis for the cases of Earth and Mars. Using the computed seismograms, calculated by the summation of the normal modes of the full planet (e.g. with atmosphere) the properties of the seismic source can be obtained. Its duration is typically associated to the radiation duration of shock waves until they reach the linear regime of propagation. These transition times are comparatively analyzed, for providing constraints on the seismic source duration on Earth and Mars. In the case of Earth, we test our approach with the Chelyabinsk superbolide. The computed seismograms are used in order to perform the inversion of the source, by comparison with the data of the Global Seismographic Network. The results are interpreted and compared with other observations. In the case of Mars, equivalent sources are similarly modeled in different atmospheric, impact size and lithospheric conditions.

  8. Effects of surface topography on ground shaking prediction: implications for seismic hazard analysis and recommendations for seismic design

    NASA Astrophysics Data System (ADS)

    Barani, Simone; Massa, Marco; Lovati, Sara; Spallarossa, Daniele

    2014-06-01

    This study examines the role of topographic effects on the prediction of earthquake ground motion. Ground motion prediction equations (GMPEs) are mathematical models that estimate the shaking level induced by an earthquake as a function of several parameters, such as magnitude, source-to-site distance, style of faulting and ground type. However, little importance is given to the effects of topography, which, as known, may play a significant role on the level, duration and frequency content of ground motion. Ridges and crests are often lost inside the large number of sites considered in the definition of a GMPE. Hence, it is presumable that current GMPEs are unable to accurately predict the shaking level at the top of a relief. The present work, which follows the article of Massa et al. about topographic effects, aims at overcoming this limitation by amending an existing GMPE with an additional term to account for the effects of surface topography at a specific site. First, experimental ground motion values and ground motions predicted by the attenuation model of Bindi et al. for five case studies are compared and contrasted in order to quantify their discrepancy and to identify anomalous behaviours of the sites investigated. Secondly, for the site of Narni (Central Italy), amplification factors derived from experimental measurements and numerical analyses are compared and contrasted, pointing out their impact on probabilistic seismic hazard analysis and design norms. In particular, with reference to the Italian building code, our results have highlighted the inadequacy of the national provisions concerning the definition of the seismic load at top of ridges and crests, evidencing a significant underestimation of ground motion around the site resonance frequency.

  9. The influence of climatically-driven surface loading variations on continental strain and seismicity

    NASA Astrophysics Data System (ADS)

    Craig, Tim; Calais, Eric; Fleitout, Luce; Bollinger, Laurent; Scotti, Oona

    2016-04-01

    In slowly deforming regions of plate interiors, secondary sources of stress and strain can result in transient deformation rates comparable to, or greater than, the background tectonic rates. Highly variable in space and time, these transients have the potential to influence the spatio-temporal distribution of seismicity, interfering with any background tectonic effects to either promote or inhibit the failure of pre-existing faults, and potentially leading to a clustered, or 'pulse-like', seismic history. Here, we investigate the ways in which the large-scale deformation field resulting from climatically-controlled changes in surface ice mass over the Pleistocene and Holocene may have influenced not only the seismicity of glaciated regions, but also the wider seismicity around the ice periphery. We first use a set of geodynamic models to demonstrate that a major pulse of seismic activity occurring in Fennoscandia, coincident with the time of end-glaciation, occurred in a setting where the contemporaneous horizontal strain-rate resulting from the changing ice mass, was extensional - opposite to the reverse sense of coseismic displacement accommodated on these faults. Therefore, faulting did not release extensional elastic strain that was building up at the time of failure, but compressional elastic strain that had accumulated in the lithosphere on timescales longer than the glacial cycle, illustrating the potential for a non-tectonic trigger to tap in to the background tectonic stress-state. We then move on to investigate the more distal influence that changing ice (and ocean) volumes may have had on the evolving strain field across intraplate Europe, how this is reflected in the seismicity across intraplate Europe, and what impact this might have on the paleoseismic record.

  10. Surface uplift and time-dependent seismic hazard due to fluid-injection in eastern Texas

    NASA Astrophysics Data System (ADS)

    Shirzaei, M.; Ellsworth, W. L.; Tiampo, K. F.; González, P. J.; Manga, M.

    2015-12-01

    US states such as Texas and Oklahoma that produce high-volumes of unconventional oil and gas, are facing a sharp increase in seismicity. Observations of the associated surface deformation and accompanying physical models that unequivocally link the seismicity and waste water injection are scarce. Here, we find that the waste water injection in eastern Texas causes uplift, detectable using radar interferometric data. Combining the uplift and injection data through a poroelastic model allows for the resolution of a complex crustal distribution of hydraulic conductivity and pore pressure. We find that the ~5 years pore pressure increase is capable of triggering the 17 May 2012, Mw 4.8 earthquake, the largest event recorded in east Texas. This study shows that surface deformation data are vital in order to constrain the spatiotemporal variations of the stress field in the vicinity of injection sites.

  11. The Seismic Effect of Impacts on Asteroid Surface Morphology: Early Modeling Results

    NASA Technical Reports Server (NTRS)

    Richardson, J. E.; Melosh, H. J.; Greenberg, R.

    2004-01-01

    In recent years, spacecraft observations of asteroids 951 Gaspra, 243 Ida, 253 Mathilde, and 433 Eros have shown the overriding dominance of impact processes with regard to the structure and appearance of these small, irregular bodies. One currently unanswered question is: to what degree does seismic shaking from impacts affect the surface morphology of these bodies? Through detailed modeling, we begin to address this question.

  12. Inherited structures impact on co-seismic surface deformation pattern during the 2013 Balochistan, Pakistan, earthquake

    NASA Astrophysics Data System (ADS)

    Vallage, Amaury; Klinger, Yann; Grandin, Raphael; Delorme, Arthur; Pierrot-Deseilligny, Marc

    2016-04-01

    The understanding of earthquake processes and the interaction of earthquake rupture with Earth's free surface relies on the resolution of the observations. Recent and detailed post-earthquake measurements bring new insights on shallow mechanical behavior of rupture processes as it becomes possible to measure and locate surficial deformation distribution. The 2013 Mw 7.7 Balochistan earthquake, Pakistan, offers a nice opportunity to comprehend where and why surficial deformation might differs from at-depth localized slip. This earthquake ruptured the Hoshab fault over 200 km; the motion was mainly left lateral with a small and discontinuous vertical component in the southern part of the rupture. Using images with the finest resolution currently available, we measured the surface displacement amplitude and its orientation at the ground surface (including the numerous tensile cracks). We combined these measurements with the 1:500 scale ground rupture map to focus on the behavior of the frontal rupture in the area where deformation distributes. Comparison with orientations of inherited tectonic structures, visible in older rocks formation surrounding the actual 2013 rupture, shows the control exercised by such structures on co-seismic rupture distribution. Such observation raises the question on how pre-existing tectonic structures in a medium, mapped in several seismically active places around the globe; can control the co-seismic distribution of the deformation during earthquakes.

  13. A Vs30-derived Near-surface Seismic Velocity Model

    NASA Astrophysics Data System (ADS)

    Ely, G. P.; Jordan, T. H.; Small, P.; Maechling, P. J.

    2010-12-01

    Shallow material properties, S-wave velocity in particular, strongly influence ground motions, so must be accurately characterized for ground-motion simulations. Available near-surface velocity information generally exceeds that which is accommodated by crustal velocity models, such as current versions of the SCEC Community Velocity Model (CVM-S4) or the Harvard model (CVM-H6). The elevation-referenced CVM-H voxel model introduces rasterization artifacts in the near-surface due to course sample spacing, and sample depth dependence on local topographic elevation. To address these issues, we propose a method to supplement crustal velocity models, in the upper few hundred meters, with a model derived from available maps of Vs30 (the average S-wave velocity down to 30 meters). The method is universally applicable to regions without direct measures of Vs30 by using Vs30 estimates from topographic slope (Wald, et al. 2007). In our current implementation for Southern California, the geology-based Vs30 map of Wills and Clahan (2006) is used within California, and topography-estimated Vs30 is used outside of California. Various formulations for S-wave velocity depth dependence, such as linear spline and polynomial interpolation, are evaluated against the following priorities: (a) capability to represent a wide range of soil and rock velocity profile types; (b) smooth transition to the crustal velocity model; (c) ability to reasonably handle poor spatial correlation of Vs30 and crustal velocity data; (d) simplicity and minimal parameterization; and (e) computational efficiency. The favored model includes cubic and square-root depth dependence, with the model extending to a depth of 350 meters. Model parameters are fit to Boore and Joyner's (1997) generic rock profile as well as CVM-4 soil profiles for the NEHRP soil classification types. P-wave velocity and density are derived from S-wave velocity by the scaling laws of Brocher (2005). Preliminary assessment of the new model

  14. Vertical directivities of seismic arrays on the ground surface

    NASA Astrophysics Data System (ADS)

    Shiraishi, H.; Asanuma, H.

    2012-12-01

    Microtremor survey method (MSM) is a technique to estimate subsurface velocity structures by inverting phase velocities of the surface waves in the microtremors. We can explorer the S-wave velocity structures at significantly lower expenses by the MSM than the conventional geophysical techniques because of its passive nature. Coherent waves across an array are identified in the MSM, and, therefore, all the existing velocity inversion methods have been deduced under an implicit assumption of horizontal velocity structure. However, it is expected that the development of the 3D inversion theory would drastically enhance applicability and reliability of the MSM. We, hence, investigated the characteristics of vertical directivities of the arrays deployed on the ground surface as an initial step for deriving the 3D MSM. We have firstly examined the response of an elemental two sensor array to which plane waves propagates from the deep crust with a certain angle of incident, and then examined the characteristics of several types of arrays, including triangular and circular arrays to clarify the characteristics of practical arrays. Real part of the complex coherence function, which has been derived to evaluate coherence of the Rayleigh wave between sensors for plane waves (Shiraishi et al., 2006), has been applied for this investigation. Our results showed that the directivity varies according to a parameter kr ( k : wave number, r : separation of the sensors ). A vertical directivity of two sensor array at kr = π shows a rotationally-symmetrical shape (Figure (a)). In contrast, an equilateral triangle array has a conspicuous directivity toward the vertical direction (cf. Figure (b)). This divergence suggests that the shape of the vertical directivity significantly depend on the geometry, and a sharp directivity toward just beneath the array can be realized by designing the vertical directivity. We concluded from this study that 3D MSM is feasible and further study to

  15. Near-surface seismic surveys at Rifle, Colorado for shallow groundwater contamination risk assessment

    NASA Astrophysics Data System (ADS)

    Chen, J.; Zelt, C. A.; Levander, A.

    2013-12-01

    In August 2012, we carried out a series of seismic surveys at a site located approximately 0.3 mile east of the city of Rifle in Garfield County, Colorado. The ground water beneath this site was contaminated by former vanadium and uranium ore-processing operations from 1924 through 1958. The site is on an alluvial terrace created by a flood-plain meander of the Colorado River. On the south side, the terrace is bounded by a steep descending slope to the Colorado River; on the other sides, it is bounded by ascending slopes of the more resistant sedimentary rocks of the Wasatch Formation. Although remedial actions have been taken to remove the contaminated surface materials, there are still potential risks from residual materials and redistribution of the contaminated water harming human health. This seismic project, funded by The U.S. Department of Energy, was designed to provide hydrogeologic information through sub-surface velocity model building and imaging of the water aquifer. A 3D compressional wave seismic survey covers an area that is 96 m in the N-S direction by 60 m in the E-W direction. An orthogonal, symmetric receiver and source template was used with 24 receiver lines, 96 channels per receiver line, and 2.5 m between lines. The inline shot and receiver spacing is 2 m and 1 m, respectively. The source was an accelerated weight drop striking a metal plate. The source has a dominant frequency at ~60 Hz, and is down by 20 db at 20 Hz and 150 Hz, providing data suitable for seismic tomography and seismic migration methods. Besides this 3D survey, three other seismic experiments were performed: (1) a 2D multi-component source and receiver survey, (2) a 3D surface wave experiment using 4.5 Hz geophones, and (3) an ambient noise experiment using 4.5 Hz geophones to record passing vehicles and trains. Preliminary results of the data analysis will be presented.

  16. Mid-Lithospheric boundary below oceans from seismic surface waves

    NASA Astrophysics Data System (ADS)

    Montagner, Jean-Paul; Burgos, Gael; Beucler, Eric; Capdeville, Yann; Mocquet, Antoine

    2014-05-01

    The nature of LithosphereAsthenosphere boundary (LAB) is controversial according to different types of observations. Using a massive dataset of surface wave dispersions in a broad frequency range (15300s), we have developed a 3D tomographic model (1st order perturbation theory) of the upper mantle at the global scale. It is used to derive maps of LAB from the resolved elastic parameters. The key effects of shallow layers and anisotropy are taken into account in the inversion process. We investigate LAB distributions primarily below oceans according to three different proxies which corresponds to the base of the lithosphere from the vertically polarized shear velocity variation at depth, from the changes in orientation of the fast axis of azimuthal anisotropy and from the maximum of the gradient of the radial anisotropy positive anomaly. The LAB depth determinations of the different proxies are consistent for the different oceanic regions. The estimations of the LAB depth based on the shear velocity proxy increase from thin (20 km) lithosphere in the ridges to thick (120-130 km) old ocean lithosphere. LAB depths inferred from azimuthal anisotropy proxy show deeper values for the increasing oceanic lithosphere (130-135 km). The radial anisotropy proxy presents a very fast increase of the LAB depth from the ridges, from 50 km to older ocean where it reaches a remarkable monotonic sub horizontal profile (70-80 km). The results present two types of pattern of the age of oceanic lithosphere evolution with the LAB depth. The shear velocity and azimuthal anisotropy proxies show age dependent profiles in agreement with thermal plate models while the LAB based on radial anisotropy is characterized by a shallower depth, defining a sub horizontal interface (mid-lithospheric boundary) with a very small age dependence for all three main oceans (Pacific, Atlantic and Indian). These different patterns raise questions about the nature of the LAB in the oceanic regions, and of the

  17. New methods for engineering site characterization using reflection and surface wave seismic survey

    NASA Astrophysics Data System (ADS)

    Chaiprakaikeow, Susit

    This study presents two new seismic testing methods for engineering application, a new shallow seismic reflection method and Time Filtered Analysis of Surface Waves (TFASW). Both methods are described in this dissertation. The new shallow seismic reflection was developed to measure reflection at a single point using two to four receivers, assuming homogeneous, horizontal layering. It uses one or more shakers driven by a swept sine function as a source, and the cross-correlation technique to identify wave arrivals. The phase difference between the source forcing function and the ground motion due to the dynamic response of the shaker-ground interface was corrected by using a reference geophone. Attenuated high frequency energy was also recovered using the whitening in frequency domain. The new shallow seismic reflection testing was performed at the crest of Porcupine Dam in Paradise, Utah. The testing used two horizontal Vibroseis sources and four receivers for spacings between 6 and 300 ft. Unfortunately, the results showed no clear evidence of the reflectors despite correction of the magnitude and phase of the signals. However, an improvement in the shape of the cross-correlations was noticed after the corrections. The results showed distinct primary lobes in the corrected cross-correlated signals up to 150 ft offset. More consistent maximum peaks were observed in the corrected waveforms. TFASW is a new surface (Rayleigh) wave method to determine the shear wave velocity profile at a site. It is a time domain method as opposed to the Spectral Analysis of Surface Waves (SASW) method, which is a frequency domain method. This method uses digital filtering to optimize bandwidth used to determine the dispersion curve. Results from testings at three different sites in Utah indicated good agreement with the dispersion curves measured using both TFASW and SASW methods. The advantage of TFASW method is that the dispersion curves had less scatter at long wavelengths as a

  18. Small-scale seismic inversion using surface waves extracted from noise cross correlation.

    PubMed

    Gouédard, Pierre; Roux, Philippe; Campillo, Michel

    2008-03-01

    Green's functions can be retrieved between receivers from the correlation of ambient seismic noise or with an appropriate set of randomly distributed sources. This principle is demonstrated in small-scale geophysics using noise sources generated by human steps during a 10-min walk in the alignment of a 14-m-long accelerometer line array. The time-domain correlation of the records yields two surface wave modes extracted from the Green's function between each pair of accelerometers. A frequency-wave-number Fourier analysis yields each mode contribution and their dispersion curve. These dispersion curves are then inverted to provide the one-dimensional shear velocity of the near surface.

  19. Seismicity and structure of Akutan and Makushin Volcanoes, Alaska, using joint body and surface wave tomography

    NASA Astrophysics Data System (ADS)

    Syracuse, E. M.; Maceira, M.; Zhang, H.; Thurber, C. H.

    2015-02-01

    Joint inversions of seismic data recover models that simultaneously fit multiple constraints while playing upon the strengths of each data type. Here we jointly invert 14 years of local earthquake body wave arrival times from the Alaska Volcano Observatory catalog and Rayleigh wave dispersion curves based upon ambient noise measurements for local Vp, Vs, and hypocentral locations at Akutan and Makushin Volcanoes using a new joint inversion algorithm. The velocity structure and relocated seismicity of both volcanoes are significantly more complex than many other volcanoes studied using similar techniques. Seismicity is distributed among several areas beneath or beyond the flanks of both volcanoes, illuminating a variety of volcanic and tectonic features. The velocity structures of the two volcanoes are exemplified by the presence of narrow high-Vp features in the near surface, indicating likely current or remnant pathways of magma to the surface. A single broad low-Vp region beneath each volcano is slightly offset from each summit and centered at approximately 7 km depth, indicating a potential magma chamber, where magma is stored over longer time periods. Differing recovery capabilities of the Vp and Vs data sets indicate that the results of these types of joint inversions must be interpreted carefully.

  20. Seismicity and structure of Akutan and Makushin Volcanoes, Alaska, using joint body and surface wave tomography

    DOE PAGES

    Syracuse, E. M.; Maceira, M.; Zhang, H.; Thurber, C. H.

    2015-02-18

    Joint inversions of seismic data recover models that simultaneously fit multiple constraints while playing upon the strengths of each data type. Here, we jointly invert 14 years of local earthquake body wave arrival times from the Alaska Volcano Observatory catalog and Rayleigh wave dispersion curves based upon ambient noise measurements for local Vp, Vs, and hypocentral locations at Akutan and Makushin Volcanoes using a new joint inversion algorithm.The velocity structure and relocated seismicity of both volcanoes are significantly more complex than many other volcanoes studied using similar techniques. Seismicity is distributed among several areas beneath or beyond the flanks ofmore » both volcanoes, illuminating a variety of volcanic and tectonic features. The velocity structures of the two volcanoes are exemplified by the presence of narrow high-Vp features in the near surface, indicating likely current or remnant pathways of magma to the surface. A single broad low-Vp region beneath each volcano is slightly offset from each summit and centered at approximately 7 km depth, indicating a potential magma chamber, where magma is stored over longer time periods. Differing recovery capabilities of the Vp and Vs datasets indicate that the results of these types of joint inversions must be interpreted carefully.« less

  1. Seismicity and structure of Akutan and Makushin Volcanoes, Alaska, using joint body and surface wave tomography

    SciTech Connect

    Syracuse, E. M.; Maceira, M.; Zhang, H.; Thurber, C. H.

    2015-02-18

    Joint inversions of seismic data recover models that simultaneously fit multiple constraints while playing upon the strengths of each data type. Here, we jointly invert 14 years of local earthquake body wave arrival times from the Alaska Volcano Observatory catalog and Rayleigh wave dispersion curves based upon ambient noise measurements for local Vp, Vs, and hypocentral locations at Akutan and Makushin Volcanoes using a new joint inversion algorithm.The velocity structure and relocated seismicity of both volcanoes are significantly more complex than many other volcanoes studied using similar techniques. Seismicity is distributed among several areas beneath or beyond the flanks of both volcanoes, illuminating a variety of volcanic and tectonic features. The velocity structures of the two volcanoes are exemplified by the presence of narrow high-Vp features in the near surface, indicating likely current or remnant pathways of magma to the surface. A single broad low-Vp region beneath each volcano is slightly offset from each summit and centered at approximately 7 km depth, indicating a potential magma chamber, where magma is stored over longer time periods. Differing recovery capabilities of the Vp and Vs datasets indicate that the results of these types of joint inversions must be interpreted carefully.

  2. Surface dynamic deformation estimates from local seismicity: the Itoiz reservoir, Spain

    NASA Astrophysics Data System (ADS)

    Santoyo, Miguel A.; Martínez-Garzón, Patricia; García-Jerez, Antonio; Luzón, Francisco

    2016-07-01

    We analyze the ground motion time histories due to the local seismicity near the Itoiz reservoir to estimate the near-source, surface 3D displacement gradients and dynamic deformations. The seismic data were obtained by a semipermanent broadband and accelerometric network located on surface and at underground sites. The dynamic deformation field was calculated by two different methodologies: first, by the seismo-geodetic method using the data from a three-station microarray located close to the dam, and second, by single station estimates of the displacement gradients. The dynamic deformations obtained from both methods were compared and analyzed in the context of the local free-field effects. The shallow 1D velocity structure was estimated from the seismic data by modeling the body wave travel times. Time histories obtained from both methods result quite similar in the time window of body wave arrivals. The strain misfits between methods vary from 1.4 to 35.0 % and rotational misfits vary from 2.5 to 36.0 %. Amplitudes of displacement gradients vary in the range of 10-8 to 10-7 strains. From these results, a new scaling analysis by numerical modeling is proposed in order to estimate the peak dynamic deformations for different magnitudes, up to the expected maximum M w in the region (M5.5). Peak dynamic deformations due to local M w5.5 earthquakes would reach amplitudes of 10-5 strain and 10-3 radians at the Itoiz dam. The single station method shows to be an adequate option for the analysis of local seismicity, where few three-component stations are available. The results obtained here could help to extend the applicability of these methodologies to other sites of engineering interest.

  3. Characterization of the upper surface of the Philippine Sea plate beneath Kanto, central Japan: insight from seismic reflection profiling

    NASA Astrophysics Data System (ADS)

    Sato, H.; Abe, S.; Iwasaki, T.; Kurashimo, E.; Okaya, D. A.; Sakai, S.; Kawanaka, T.; Hirata, N.

    2010-12-01

    Beneath metropolitan Tokyo, the Philippine Sea plate (PHS) has been subducted on the Pacific plate (PAC). Due to shallow subduction of Philippine Sea plate (PHS), intraslab earthquake of PHS can also produce significant damage of Tokyo metropolitan area. To construct source fault models, we have carried out seismic reflection profiling since 2002 and acquired seismic reflection data from 9 seismic lines, including 2009 Sagami trough and 2010 Kujukuri seismic survey. Due to strong impedance contrast of plate interface, the upper surface of PHS was imaged down to maximum 40 km in depth. The obtained seismic profiles portrayed the shallow geometry of the PHS. The combined seismic section from Izu peninsula to Tokyo (2009 Sagami trough and 2003 Tokyo bay seismic sections) shows strong reflectivity in the deeper part (17 to 27 km) and also shallower part (5 to 10 km). Base on the co-seismic displacement of the 1923 Kanto earthquake (M7.9) and slip-deficit rate determined by GPS observations, the asperity zone is clearly identified along the combined seismic line. By comparison, the zone of asperity is marked by the area of low reflectivity, relatively flat geometry and Vp > 6 km/sec. The subducted PHS slab beneath Kanto consists of fore-arc and volcanic-arc of young geologic age. The slab geometry obtained by seismic reflection suggests strong deformation. Three seismic lines across the north to northwestern part of the Izu collision zone demonstrate the ridge shaped antiform of the PHS slab. Judging from overall geometry of PHS slab beneath Kanto, the deformation of the slab probably produced by the northward subduction of PHS (> 1 Ma) and interaction with underlying cold PAC slab.

  4. Source estimation with surface-related multiples—fast ambiguity-resolved seismic imaging

    NASA Astrophysics Data System (ADS)

    Tu, Ning; Aravkin, Aleksandr; van Leeuwen, Tristan; Lin, Tim; Herrmann, Felix J.

    2016-06-01

    We address the problem of obtaining a reliable seismic image without prior knowledge of the source wavelet, especially from data that contain strong surface-related multiples. Conventional reverse-time migration requires prior knowledge of the source wavelet, which is either technically or computationally challenging to accurately determine; inaccurate estimates of the source wavelet can result in seriously degraded reverse-time migrated images, and therefore wrong geological interpretations. To solve this problem, we present a `wavelet-free' imaging procedure that simultaneously inverts for the source wavelet and the seismic image, by tightly integrating source estimation into a fast least-squares imaging framework, namely compressive imaging, given a reasonably accurate background velocity model. However, this joint inversion problem is difficult to solve as it is plagued with local minima and the ambiguity with respect to amplitude scalings because of the multiplicative, and therefore nonlinear, appearance of the source wavelet in the otherwise linear formalism. We have found a way to solve this nonlinear joint-inversion problem using a technique called variable projection, and a way to overcome the scaling ambiguity by including surface-related multiples in our imaging procedure following recent developments in surface-related multiple prediction by sparse inversion. As a result, we obtain without prior knowledge of the source wavelet high-resolution seismic images, comparable in quality to images obtained assuming the true source wavelet is known. By leveraging the computationally efficient compressive-imaging methodology, these results are obtained at affordable computational costs compared with conventional processing work flows that include surface-related multiple removal and reverse-time migration.

  5. Surface and downhole shear wave seismic methods for thick soil site investigations

    USGS Publications Warehouse

    Hunter, J.A.; Benjumea, B.; Harris, J.B.; Miller, R.D.; Pullan, S.E.; Burns, R.A.; Good, R.L.

    2002-01-01

    Shear wave velocity-depth information is required for predicting the ground motion response to earthquakes in areas where significant soil cover exists over firm bedrock. Rather than estimating this critical parameter, it can be reliably measured using a suite of surface (non-invasive) and downhole (invasive) seismic methods. Shear wave velocities from surface measurements can be obtained using SH refraction techniques. Array lengths as large as 1000 m and depth of penetration to 250 m have been achieved in some areas. High resolution shear wave reflection techniques utilizing the common midpoint method can delineate the overburden-bedrock surface as well as reflecting boundaries within the overburden. Reflection data can also be used to obtain direct estimates of fundamental site periods from shear wave reflections without the requirement of measuring average shear wave velocity and total thickness of unconsolidated overburden above the bedrock surface. Accurate measurements of vertical shear wave velocities can be obtained using a seismic cone penetrometer in soft sediments, or with a well-locked geophone array in a borehole. Examples from thick soil sites in Canada demonstrate the type of shear wave velocity information that can be obtained with these geophysical techniques, and show how these data can be used to provide a first look at predicted ground motion response for thick soil sites. ?? 2002 Published by Elsevier Science Ltd.

  6. Frequency-dependent traveltime tomography for near-surface seismic refraction data

    NASA Astrophysics Data System (ADS)

    Zelt, Colin A.; Chen, Jianxiong

    2016-10-01

    Traveltime tomography is the main method by which the Earth's seismic velocity is determined on all scales, from the near-surface (<100 m) to the core. Usually traveltime tomography uses ray theory, an infinite-frequency approximation of wave propagation. A theory developed in global seismology to account for the finite-frequency nature of seismic data, known as finite-frequency traveltime tomography (FFTT), can theoretically provide a more accurate estimation of velocity. But the FFTT theory is generally not applicable to near-surface data because there is no reference velocity model known in advance that is capable of yielding synthetic waveforms that are close enough to the recorded seismograms to yield a reliable delay time. Also, there is usually no reference model for which the unknown velocity model represents a small (linear) perturbation from the reference model. This paper presents a frequency dependent form of non-linear traveltime tomography specifically designed for near-surface seismic data in which a starting model, iterative approach with recalculated travel paths at each iteration, and the calculation of a frequency-dependent total traveltime, as opposed to a delay time, are used. Frequency-dependent traveltime tomography (FDTT) involves two modifications to conventional traveltime tomography: (1) the calculation of frequency-dependent traveltimes using wavelength-dependent velocity smoothing (WDVS) and (2) the corresponding sensitivity kernels that arise from using WDVS. Results show that the former modification is essential to achieve significant benefits from FDTT, whereas the latter is optional in that similar results can be achieved using infinite-frequency kernels. The long seismic wavelengths relative to the total path lengths and the size of subsurface heterogeneities of typical near-surface data means the improvements over ray theory tomography are significant. The benefits of FDTT are demonstrated using conventional minimum

  7. Frequency-dependent traveltime tomography for near-surface seismic refraction data

    NASA Astrophysics Data System (ADS)

    Zelt, Colin A.; Chen, Jianxiong

    2016-07-01

    Traveltime tomography is the main method by which the Earth's seismic velocity is determined on all scales, from the near-surface (< 100 m) to the core. Usually traveltime tomography uses ray theory, an infinite-frequency approximation of wave propagation. A theory developed in global seismology to account for the finite-frequency nature of seismic data, known as finite-frequency traveltime tomography (FFTT), can theoretically provide a more accurate estimation of velocity. But the FFTT theory is generally not applicable to near-surface data because there is no reference velocity model known in advance that is capable of yielding synthetic waveforms that are close enough to the recorded seismograms to yield a reliable delay time. Also, there is usually no reference model for which the unknown velocity model represents a small (linear) perturbation from the reference model. This paper presents a frequency dependent form of nonlinear traveltime tomography specifically designed for near-surface seismic data in which a starting model, iterative approach with recalculated travel paths at each iteration, and the calculation of a frequency-dependent total traveltime, as opposed to a delay time, are used. Frequency-dependent traveltime tomography (FDTT) involves two modifications to conventional traveltime tomography: (1) the calculation of frequency-dependent traveltimes using wavelength-dependent velocity smoothing (WDVS), and (2) the corresponding sensitivity kernels that arise from using WDVS. Results show that the former modification is essential to achieve significant benefits from FDTT, whereas the latter is optional in that similar results can be achieved using infinite-frequency kernels. The long seismic wavelengths relative to the total path lengths and the size of subsurface heterogeneities of typical near-surface data means the improvements over ray theory tomography are significant. The benefits of FDTT are demonstrated using conventional minimum

  8. Laser- and Radar-based Mission Concepts for Suborbital and Spaceborne Monitoring of Seismic Surface Waves

    SciTech Connect

    Foxall, W; Schultz, C A; Tralli, D M

    2004-09-21

    The development of a suborbital or spaceborne system to monitor seismic waves poses an intriguing prospect for advancing the state of seismology. This capability would enable an unprecedented global mapping of the velocity structure of the earth's crust, understanding of earthquake rupture dynamics and wave propagation effects, and event source location, characterization and discrimination that are critical for both fundamental earthquake research and nuclear non-proliferation applications. As part of an ongoing collaboration between LLNL and JPL, an advanced mission concept study assessed architectural considerations and operational and data delivery requirements, extending two prior studies by each organization--a radar-based satellite system (JPL) for earthquake hazard assessment and a feasibility study of space- or UAV-based laser seismometer systems (LLNL) for seismic event monitoring. Seismic wave measurement requirements include lower bounds on detectability of specific seismic sources of interest and wave amplitude accuracy for different levels of analysis, such as source characterization, discrimination and tomography, with a 100 {micro}m wave amplitude resolution for waves nominally traveling 5 km/s, an upper frequency bound based on explosion and earthquake surface displacement spectra, and minimum horizontal resolution (1-5 km) and areal coverage, in general and for targeted observations. For a radar system, corresponding engineering and operational factors include: Radar frequency (dictated by required wave amplitude measurement accuracy and maximizing ranging, Doppler or interferometric sensitivity), time sampling (maximum seismic wave frequency and velocity), and overall system considerations such as mass, power and data rate. Technical challenges include characterization of, and compensation for, phase distortion resulting from atmospheric and ionospheric perturbations and turbulence, and effects of ground scattering characteristics and seismic

  9. Global Seismic Event Detection Using Surface Waves: 15 Possible Antarctic Glacial Sliding Events

    NASA Astrophysics Data System (ADS)

    Chen, X.; Shearer, P. M.; Walker, K. T.; Fricker, H. A.

    2008-12-01

    To identify overlooked or anomalous seismic events not listed in standard catalogs, we have developed an algorithm to detect and locate global seismic events using intermediate-period (35-70s) surface waves. We apply our method to continuous vertical-component seismograms from the global seismic networks as archived in the IRIS UV FARM database from 1997 to 2007. We first bandpass filter the seismograms, apply automatic gain control, and compute envelope functions. We then examine 1654 target event locations defined at 5 degree intervals and stack the seismogram envelopes along the predicted Rayleigh-wave travel times. The resulting function has spatial and temporal peaks that indicate possible seismic events. We visually check these peaks using a graphical user interface to eliminate artifacts and assign an overall reliability grade (A, B or C) to the new events. We detect 78% of events in the Global Centroid Moment Tensor (CMT) catalog. However, we also find 840 new events not listed in the PDE, ISC and REB catalogs. Many of these new events were previously identified by Ekstrom (2006) using a different Rayleigh-wave detection scheme. Most of these new events are located along oceanic ridges and transform faults. Some new events can be associated with volcanic eruptions such as the 2000 Miyakejima sequence near Japan and others with apparent glacial sliding events in Greenland (Ekstrom et al., 2003). We focus our attention on 15 events detected from near the Antarctic coastline and relocate them using a cross-correlation approach. The events occur in 3 groups which are well-separated from areas of cataloged earthquake activity. We speculate that these are iceberg calving and/or glacial sliding events, and hope to test this by inverting for their source mechanisms and examining remote sensing data from their source regions.

  10. Q AS A LITHOLOGICAL/HYDROCARBON INDICATOR: FROM FULL WAVEFORM SONIC TO 3D SURFACE SEISMIC

    SciTech Connect

    Jorge O. Parra; C.L. Hackert; L. Wilson; H.A. Collier; J. Todd Thomas

    2006-03-31

    The goal of this project was to develop a method to exploit viscoelastic rock and fluid properties to greatly enhance the sensitivity of surface seismic measurements to the presence of hydrocarbon saturation. To reach the objective, Southwest Research Institute scientists used well log, lithology, production, and 3D seismic data from an oil reservoir located on the Waggoner Ranch in north central Texas. The project was organized in three phases. In the first phase, we applied modeling techniques to investigate seismic- and acoustic-frequency wave attenuation and its effect on observable wave attributes. We also gathered existing data and acquired new data from the Waggoner Ranch field, so that all needed information was in place for the second phase. During the second phase, we developed methods to extract attenuation from borehole acoustic and surface seismic data. These methods were tested on synthetic data constructed from realistic models and real data. In the third and final phase of the project, we applied this technology to a full data set from the Waggoner site. The results presented in this Final Report show that geological conditions at the site did not allow us to obtain interpretable results from the Q processing algorithm for 3D seismic data. However, the Q-log processing algorithm was successfully applied to full waveform sonic data from the Waggoner site. A significant part of this project was technology transfer. We have published several papers and conducted presentations at professional conferences. In particular, we presented the Q-log algorithm and applications at the Society of Exploration Geophysicists (SEG) Development and Production Forum in Austin, Texas, in May 2005. The presentation attracted significant interest from the attendees and, at the request of the SEG delegates, it was placed on the Southwest Research Institute Internet site. The presentation can be obtained from the following link: http://www.swri.org/4org/d15/elecsys

  11. Body and Surface-wave ambient noise seismic interferometry in the Salton Sea Geothermal Field, California

    NASA Astrophysics Data System (ADS)

    Sabey, L.; Hole, J. A.; Han, L.; Stock, J. M.; Fuis, G. S.

    2013-12-01

    Seismic reflection and refraction data were acquired as a part of the Salton Seismic Imaging Project in March 2011. Alongside traditional explosive source recording, a dense array of 486 seismometers across the Salton Sea Geothermal Field and Brawley Seismic Zone recorded 135 hours of natural noise sources. The geothermal field is located within the Imperial Valley in Southern California and is bordered by the southern end of the Salton Sea. There is abundant microseismicity recorded in the area, including over 100-recorded earthquakes, wave action, geothermal pumping operations, a railroad, and two highways. Volcanism associated with rifting processes provides a prolific heat source to the system marking the Salton Sea Geothermal Field as one of the largest and hottest geothermal fields in California. Seismic interferometry is a technique that uses continuous recordings of natural noise to create a 'virtual source' by cross-correlation of receiver pairs followed by stacking. This method has been highly successful for surface waves and a few previous studies have shown evidence of body waves and reflections. As anticipated the abundant tectonic and induced noise sources within our study area produced visible surface and body waves. Inclusion of the earthquakes with normalized amplitudes improved overall data quality. The virtual shots from our data our compare well to our twelve explosive shots at near offsets. The highest quality virtual source gathers are produced near anthropogenic noise sources. In particular, one large geothermal plant acted as a sufficiently strong point source producing a gather similar to what we would see from an explosive source. Surface waves recorded on 4.5-Hz geophones were retrievable from 1-6Hz after cross-correlation and stacking. Up to 30km of body waves were also observed in the 25-30Hz range. Future studies will include surface wave dispersion analysis and attempt body wave reflection imaging. The 100-meter spacing of our

  12. A one year long continuous record of seismic activity and surface motion at the tongue of Rhonegletscher (Valais, Switzerland)

    NASA Astrophysics Data System (ADS)

    Dalban Canassy, Pierre; Röösli, Claudia; Walter, Fabian; Gabbi, Jeannette

    2014-05-01

    A critical gap in our current understanding of glaciers is how high sub-glacial water pressure controls the coupling of the glacier to its bed. Processes at the base of a glacier are inherently difficult to investigate due to their remoteness. Investigation of the sub-glacial environment with passive seismic methods is an innovative, rapidly growing interdisciplinary and promising endeavor. In combination with observations of surface motion and basal water pressure, this method is ideally suited to localize and quantify frictional and fracture processes which occur during periods of rapidly changing sub-glacial water pressure with consequent stress redistribution at the contact interface between ice and bed. Here we present the results of the first one-year-long glacier seismic monitoring performed on an Alpine glacier to our knowledge. Together with records of surface motion and hydrological measurements, we examine whether seasonal changes can be captured by seismic recording. Experiments were carried out from June 2012 to July 2013 on Rhonegletscher (Valais, Switzerland), by means of 3 three-components seismometers settled close to the tongue in 2 meters boreholes. An additional array of eleven sensors installed at the ice surface was also maintained during September 2012, in order to achieve more accurate icequakes locations. A high seismic emission is observed on Rhonegletscher, with icequakes located close to the surface or in the vicinity of the bedrock. The temporal distribution of seismic activity is shown to nicely reflect the seasonal evolution of the glacier hydrology, with a dramatic seismic release in early spring. During summer, released seismic activity is generally driven by diurnal ice/snow melting cycle. In winter, snow-cover conditions are associated with a reduced seismic release, with nevertheless some unexpected activity possibly related to snow-pack metamorphism. Based on icequake locations derived from data recorded in September, we discuss

  13. Seismic interferometry of railroad induced ground motions: body and surface wave imaging

    NASA Astrophysics Data System (ADS)

    Quiros, Diego A.; Brown, Larry D.; Kim, Doyeon

    2016-04-01

    Seismic interferometry applied to 120 hr of railroad traffic recorded by an array of vertical component seismographs along a railway within the Rio Grande rift has recovered surface and body waves characteristic of the geology beneath the railway. Linear and hyperbolic arrivals are retrieved that agree with surface (Rayleigh), direct and reflected P waves observed by nearby conventional seismic surveys. Train-generated Rayleigh waves span a range of frequencies significantly higher than those recovered from typical ambient noise interferometry studies. Direct P-wave arrivals have apparent velocities appropriate for the shallow geology of the survey area. Significant reflected P-wave energy is also present at relatively large offsets. A common midpoint stack produces a reflection image consistent with nearby conventional reflection data. We suggest that for sources at the free surface (e.g. trains) increasing the aperture of the array to record wide angle reflections, in addition to longer recording intervals, might allow the recovery of deeper geological structure from railroad traffic. Frequency-wavenumber analyses of these recordings indicate that the train source is symmetrical (i.e. approaching and receding) and that deeper refracted energy is present although not evident in the time-offset domain. These results confirm that train-generated vibrations represent a practical source of high-resolution subsurface information, with particular relevance to geotechnical and environmental applications.

  14. Monitoring Hurricanes with a Dense Seismic Array: Joint Inversion of Seismic and Barometric Data for Surface-Pressure Source

    NASA Astrophysics Data System (ADS)

    Valentine, A. P.; Al-Attar, D.; Trampert, J.; Woodhouse, J. H.

    2014-12-01

    Tropical cyclones (hurricanes and typhoons) are mostly atmospheric phenomena but they also generate significant ground motions in the solid earth when they become strong. If a dense seismological array exists along the path of a hurricane, we can learn about some processes near the hurricane eye through seismic data. In this study, we report our analysis of Hurricane Arthur which passed near Earthscope's Transportable Array (TA), a network of seismometers located at the time along the east coast of the US. Hurricane Arthur mostly traveled along the eastern coast of the US from July 1 to July 5, 2014; however, it made landfall for a short time on the coast of North Carolina at 0315 UTC on July 4. The next few hours provided us with a short span of seismic and barometric data associated with the center of Hurricane Arthur. Our basic approach to analyze this data is the same as in a previous study we conducted of Hurricane Isaac (2012), where we analyzed the seismic amplitude-distance data and the pressure amplitude-distance data for each 6-hour location of the hurricane. Here, we performed a joint inversion of the seismic and barometric data while Hurricane Arthur was nearest the coast. Barometer data provides the information on pressure source, which is the source of seismic-wave excitation and seismic data provides the resultant wavefields. We confine our analysis to frequencies below 0.02 Hz because in higher frequency bands ocean waves created the dominant seismic waves. In a similar manner to our previous study on Hurricane Isaac, we invert for the pressure correlation length. The results were consistent with what was seen for Hurricane Isaac in that we observed a signal generated by Hurricane Arthur's eyewall. After landfall, there is a peak at about 70-80km from the center of the hurricane in both the seismic and the barometric data. We also found that the correlation length changes with distance from the hurricane center and also has a peak around 70-80km.

  15. Identification of surface wave higher modes using a methodology based on seismic noise and coda waves

    NASA Astrophysics Data System (ADS)

    Rivet, Diane; Campillo, Michel; Sanchez-Sesma, Francisco; Shapiro, Nikolaï M.; Singh, Shri Krishna

    2015-11-01

    Dispersion analysis of Rayleigh waves is performed to assess the velocity of complex structures such as sedimentary basins. At short periods several modes of the Rayleigh waves are often exited. To perform a reliable inversion of the velocity structure an identification of these modes is thus required. We propose a novel method to identify the modes of surface waves. We use the spectral ratio of the ground velocity for the horizontal components over the vertical component (H/V) measured on seismic coda. We then compare the observed values with the theoretical H/V ratio for velocity models deduced from surface wave dispersion when assuming a particular mode. We first invert the Rayleigh wave measurements retrieved from ambient noise cross-correlation with the assumptions that (1) the fundamental mode and (2) the first overtone are excited. Then we use these different velocity models to predict theoretical spectral ratios of the ground velocity for the horizontal components over the vertical component (H/V). These H/V ratios are computed under the hypothesis of equipartition of a diffuse field in a layered medium. Finally we discriminate between fundamental and higher modes by comparing the theoretical H/V ratio with the H/V ratio measured on seismic coda. In an application, we reconstruct Rayleigh waves from cross-correlations of ambient seismic noise recorded at seven broad-band stations in the Valley of Mexico. For paths within the soft quaternary sediments basin, the maximum energy is observed at velocities higher than expected for the fundamental mode. We identify that the dominant mode is the first higher mode, which suggests the importance of higher modes as the main vectors of energy in such complex structures.

  16. Seismicity on the western Greenland Ice Sheet: Surface fracture in the vicinity of active moulins

    DOE PAGES

    Carmichael, Joshua D.; Joughin, Ian; Behn, Mark D.; Das, Sarah; King, Matt A.; Stevens, Laura; Lizarralde, Dan

    2015-06-25

    We analyzed geophone and GPS measurements collected within the ablation zone of the western Greenland Ice Sheet during a ~35 day period of the 2011 melt season to study changes in ice deformation before, during, and after a supraglacial lake drainage event. During rapid lake drainage, ice flow speeds increased to ~400% of winter values, and icequake activity peaked. At times >7 days after drainage, this seismicity developed variability over both diurnal and longer periods (~10 days), while coincident ice speeds fell to ~150% of winter values and showed nightly peaks in spatial variability. Approximately 95% of all detected seismicitymore » in the lake basin and its immediate vicinity was triggered by fracture propagation within near-surface ice (<330 m deep) that generated Rayleigh waves. Icequakes occurring before and during drainage frequently were collocated with the down flow (west) end of the primary hydrofracture through which the lake drained but shifted farther west and outside the lake basin after the drainage. We interpret these results to reveal vertical hydrofracture opening and local uplift during the drainage, followed by enhanced seismicity and ice flow on the downstream side of the lake basin. This region collocates with interferometric synthetic aperture radar-measured speedup in previous years and could reflect the migration path of the meltwater supplied to the bed by the lake. The diurnal seismic signal can be associated with nightly reductions in surface melt input that increase effective basal pressure and traction, thereby promoting elevated strain in the surficial ice.« less

  17. A seismic reference model for the crust and uppermost mantle beneath China from surface wave dispersion

    NASA Astrophysics Data System (ADS)

    Shen, Weisen; Ritzwoller, Michael H.; Kang, Dou; Kim, YoungHee; Lin, Fan-Chi; Ning, Jieyuan; Wang, Weitao; Zheng, Yong; Zhou, Longquan

    2016-08-01

    Using data from more than 2000 seismic stations from multiple networks arrayed throughout China (CEArray, China Array, NECESS, PASSCAL, GSN) and surrounding regions (Korean Seismic Network, F-Net, KNET), we perform ambient noise Rayleigh wave tomography across the entire region and earthquake tomography across parts of South China and Northeast China. We produce isotropic Rayleigh wave group and phase speed maps with uncertainty estimates from 8 to 50 s period across the entire region of study, and extend them to 70 s period where earthquake tomography is performed. Maps of azimuthal anisotropy are estimated simultaneously to minimize anisotropic bias in the isotropic maps, but are not discussed here. The 3D model is produced using a Bayesian Monte Carlo formalism covering all of China, extending eastwards through the Korean Peninsula, into the marginal seas, to Japan. We define the final model as the mean and standard deviation of the posterior distribution at each location on a 0.5° × 0.5° grid from the surface to 150 km depth. Surface wave dispersion data do not strongly constrain internal interfaces, but shear wave speeds between the discontinuities in the crystalline crust and uppermost mantle are well determined. We design the resulting model as a reference model, which is intended to be useful to other researchers as a starting model, to predict seismic wave fields and observables and to predict other types of data (e.g. topography, gravity). The model and the data on which it is based are available for download. In addition, the model displays a great variety and considerable richness of geological and tectonic features in the crust and in the uppermost mantle deserving of further focus and continued interpretation.

  18. Surface-wave Tomography of East African Rift System using Ambient Seismic Noise

    NASA Astrophysics Data System (ADS)

    Kim, S.; Kang, T.; Baag, C.; Nyblade, A. A.

    2008-12-01

    The surface-wave tomography technique for the ambient seismic noise is applied to the east African rift system to investigate shallow crustal structures of the region. Even if the technique has been widely used in many regions to investigate crustal structure in the world, there have been difficulties in application of the technique to the east African region because of unstable data conditions of PASSCAL experiments. A meticulous check of record by record enables us of applying the technique to understand the tectonic environment of the region. The long-period data of one month showing good quality in cross-correlation results are used in this study. They are from the 1994-95 Tanzania Passive-Source Seismic Experiment for the Tanzania craton and its surrounding rift zone, and from the 2000-02 Ethiopia/Kenya Broadband Seismic Experiment and the adjacent permanent stations of the African Array for the Ethiopia rift. The Rayleigh- and Love-wave group-speed maps were inverted using LSQR algorithm for several period bands (5 - 50 s). The preliminary group-speed distribution maps yield results roughly consistent with regional geology. The tomographic images of the Tanzania region show a strong high velocity anomaly at the location corresponding to the Tanzania craton and low velocity anomalies at the surrounding rift regions. For the Ethiopia regions, the features of low velocity anomalies roughly agree with the Tertiary volcanic regions. Combining the Tanzania and Ethiopia broadband arrays, the outline of the east African rift system can be identified as the low velocity anomalies in the surface-wave tomographic results. The structural variation with depth and the feature of the regional shear-wave anisotropy of crust will be explored by converting group- speed dispersion curves into shear-wave velocity structure.

  19. Surface amplitude data: 3D-seismic for interpretation of sea floor geology (Louisiana Slope)

    SciTech Connect

    Roberts, H.H.

    1996-09-01

    Proliferation of 3D-seismic in support of hydrocarbon exploration/production has created new data for improved interpretation of sea floor and shallow subsurface geology. Processing of digital seismic data to enhance amplitude anomalies produces information for improved assessment of geohazards and identification of sensitive benthic communities protected by environmental regulations. Coupled with high resolution acoustic data and direct observation/sampling using a manned research submersible, surface amplitude maps add critical interpretive information for identification of sea floor features. Non-reflective zones (acoustic wipeouts) are associated with many slope features. Mud diapirs, mud mounds, mud volcanoes, gas-changed sediments, gas hydrates, slump deposits, carbonate hardgrounds, and various types of carbonate mounds are all features that exhibit this common response on high resolution seismic profiles. Amplitude data help make specific identifications. Since 1988, submersible data from mid-to-upper slope features (Garden Banks, Green Canyon, and Mississippi Canyon lease block areas) have been analyzed with conventional high resolution acoustic data and 313-amplitude extraction maps. Areas of rapid venting of sediment and hydrocarbon-charged formation fluids are clearly distinguishable from mud diapirs and areas of carbonate mounds (slow seepage). Gas hydrates occur as mounds and mounded zones along faults; products of moderate flux rates below (approx.) 500 in water depths. Gas hydrates function as stored trophic resources that support sensitive chemosynthetic communities. Amplitude extraction maps clearly identify these features by a strong low impedance amplitude anomaly. Refinement and {open_quotes}field calibration{close_quotes} of the surface amplitude extraction method may eventually lead to a new standard for evaluating geohazards and sensitive benthic communities.

  20. Joint Geophysical Imaging of the Utah Area Using Seismic Body Waves, Surface Waves and Gravity Data

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Maceira, M.; Toksoz, M. N.; Burlacu, R.; Yang, Y.

    2009-12-01

    We present a joint geophysical imaging method that makes use of seismic body wave arrival times, surface wave dispersion measurements, and gravity data to determine three-dimensional (3D) Vp and Vs models. An empirical relationship mapping densities to Vp and Vs for earth materials is used to link them together. The joint inversion method takes advantage of strengths of individual data sets and is able to better constrain the velocity models from shallower to greater depths. Combining three different data sets to jointly invert for the velocity structure is equivalent to a multiple-objective optimization problem. Because it is unlikely that the different “objectives” (data types) would be optimized by the same parameter choices, some trade-off between the objectives is needed. The optimum weighting scheme for different data types is based on relative uncertainties of individual observations and their sensitivities to model parameters. We will apply this joint inversion method to determine 3D Vp and Vs models of the Utah area. The seismic body wave arrival times are assembled from waveform data recorded by the University of Utah Seismograph Stations (UUSS) regional network for the past 7 years. The surface wave dispersion measurements are obtained from the ambient noise tomography study by the University of Colorado group using EarthScope/USArray stations. The gravity data for the Utah area is extracted from the North American Gravity Database managed by the University of Texas at El Paso. The preliminary study using the seismic body wave arrival times indicates strong low velocity anomalies in middle crust beneath some known geothermal sites in Utah. The joint inversion is expected to produce a reasonably well-constrained velocity structure of the Utah area, which is helpful for characterizing and exploring existing and potential geothermal reservoirs.

  1. Regional velocity structure in northern California from inversion of scattered seismic surface waves

    NASA Astrophysics Data System (ADS)

    Pollitz, Fred F.

    1999-07-01

    Seismic surface waves recorded by the Berkeley Digital Seismic Network have been analyzed in order to constrain three-dimensional lateral heterogeneity of the upper mantle under northern California. A total of 2164 seismograms from 173 teleseismic events were windowed for the fundamental mode Rayleigh wave, followed by estimation of complex amplitude spectra over the period range 16 to 100 s using a multiple-taper method. Since Rayleigh waves at shorter periods, particularly below 35 s, suffer from serious multipathing or "non-plane" wave arrivals, these amplitude spectra have been interpreted as the product of wavefront distortion along the teleseismic propagation path and seismic structure beneath the network. The amplitude spectra are first modeled in terms of non-plane incoming wavefields and structural phase velocity perturbations period by period. After corrections for Moho and surface topography, the phase velocity maps are inverted for three-dimensional shear velocity perturbations δνs down to a depth of 200 km. The δνs maps are in good agreement with the results of body studies over a broad spatial scale. The dominant signals are associated with the thermal effects of the active Gorda and fossil Farallon subducted slab stretching from Mount Shasta through the western Sierran foothills to the southern Great Valley and asthenospheric upwelling beneath the northern Coast Ranges. The southern Sierra Nevada Range is characterized by fast δνs down to ˜50 km and slow velocities between ˜60 and 120 km depth, in agreement with independent inferences of a cold crust and warm upper mantle, which may provide the buoyancy forces necessary to support the elevation of the range.

  2. From the Surface Topography to the Upper Mantle, Seismic constraints on the Crustal structure Across Morocco

    NASA Astrophysics Data System (ADS)

    Carbonell, Ramon; Díaz, Jordi; Gallart, Josep; Gil, Alba; Ayarza, Puy; Palomeras, Immaculada; Levander, Alan; Marti, David; Harnafi, Mimoun

    2015-04-01

    The most characteristic topographic features of Morocco are the Atlas Mountains and the Rif Coordillera. These two orogenic belts are the response of different geodynamic processes acting at lithospheric scale caused by a unique driver, the collision between two tectonic plates. Both are located within the diffuse plate boundary zone separating Africa and Europe. The boundary zone is characterized by a relatively broad zone of deformation that includes Mountain chains in southern Iberia, the Betics and the Rif cordillera in Morocco. The zone delineates the arcuate arc system of Gribraltar. Within the last decade a large international effort have been devoted to the area mostly leaded by Spanish groups with the collaboration of international research teams (including scientist form Europe and USA). Key multi-seismic projects have been developed that aim to constrain the structure, composition and tectonic scenario from south of the Atlas to the Betics, across the Rif cordillera and the Alboran basin. The multidisciplinary research program includes: natural source (earthquakes) recording with temporal deployments of broad band (BB) instrumentation and, controlled source seismic acquisition experiments where, spatially dense recording of wide-angle seismic reflection shot gathers were acquired. The passive experiments consisted on: a transect from Merzouga across the Gibraltar arc and into the Iberian peninsula (untill south of Toledo); a nearly regular grid of BB which was achieve by multiple deployments of a number of BB. The controlled source datasets were able to constrain the crustal structure and provide seismic P-wave propagation velocity models from the coast across the Rif and the Atlas. Travel-time inversion of the controlled source seismic data across the Atlas constraints a crustal root to the south of the High Atlas, and reveals mantle wedge. A limited crustal imbrication also appears in the Middle Atlas. The crustal thickness, does not exceeded 40 km in

  3. Joint inversion of Multi-frequency Electromagnetic Induction and Seismic Refraction Data For Improved Near Surface Characterization

    NASA Astrophysics Data System (ADS)

    Elwaseif, M.

    2015-12-01

    We present a joint inversion routine between multi-frequency Electromagnetic (EM) induction and seismic refraction data that is based on using both cross-gradients and disconnect constraints. The joint inverse problem was solved using an iterative nonlinear least-squares formulation. Following each iteration, the cross gradient constraint enforces structural similarities between the EM and seismic models, whereas the disconnect constraint enforces sharp boundaries between different strata within the EM model. The locations of boundaries within the EM model are assumed to be consistent with the locations of user-defined velocity contours in the seismic model. We tested our method on a challenging synthetic EM and seismic model scenario that contains water-bearing zones as well as positively and negatively correlated model parameter values. In addition, we applied our method to GEM-2 and seismic refraction field data sets acquired along a 28-m-long profile in Laramie (WY), and we precisely recorded the locations where ground surface resistivity and velocity likely changes along that line. Unlike the results of separate EM and seismic inversions and the results of joint inversion based only on a cross-gradient constraint, our method was able to detect the water-bearing zones. In addition, it better captured ground surface changes in the field data set.

  4. Shear wave velocity estimation of the near-surface materials of Chittagong City, Bangladesh for seismic site characterization

    NASA Astrophysics Data System (ADS)

    Rahman, Md. Zillur; Siddiqua, Sumi; Kamal, A. S. M. Maksud

    2016-11-01

    The average shear wave velocity of the near-surface materials down to a depth of 30 m (Vs30) is essential for seismic site characterization to estimate the local amplification factor of the seismic waves during an earthquake. Chittagong City is one of the highest risk cities of Bangladesh for its seismic vulnerability. In the present study, the Vs30 is estimated for Chittagong City using the multichannel analysis of surface waves (MASW), small scale microtremor measurement (SSMM), downhole seismic (DS), and correlation between the shear wave velocity (Vs) and standard penetration test blow count (SPT-N). The Vs30 of the near-surface materials of the city varies from 123 m/s to 420 m/s. A Vs30 map is prepared from the Vs30 of each 30 m grid using the relationship between the Holocene soil thickness and the Vs30. Based on the Vs30, the near-surface materials of Chittagong City are classified as site classes C, D, and E according to the National Earthquake Hazards Reduction Program (NEHRP), USA and as site classes B, C, and D according to the Eurocode 8. The Vs30 map can be used for seismic microzonation, future planning, and development of the city to improve the earthquake resiliency of the city.

  5. A combined surface and borehole seismic survey at the COSC-1 borehole

    NASA Astrophysics Data System (ADS)

    Simon, Helge; Krauß, Felix; Hedin, Peter; Buske, Stefan; Giese, Rüdiger; Juhlin, Christopher

    2015-04-01

    The ICDP project COSC (Collisional Orogeny in the Scandinavian Caledonides) focuses on the mid Paleozoic Caledonide Orogen in Scandinavia in order to better understand orogenic processes, from the past and in recent active mountain belts. The Scandinavian Caledonides provide a well preserved example of a Paleozoic continent-continent collision. Surface geology in combination with geophysical data provide control of the geometry of the Caledonian structure, including the allochthon and the underlying autochthon, as well as the shallow W-dipping décollement surface that separates the two and consist of a thin skin of Cambrian black shales. During spring/summer 2014 the COSC-1 borehole was drilled to approx. 2.5 km depth near the town of Åre (western Jämtland/Sweden) with nearly 100 % of core recovery and cores in best quality. After the drilling was finished, a major seismic survey was conducted in and around the COSC-1 borehole which comprised both seismic reflection and transmission experiments. Besides a high resolution zero-offset VSP (Vertical Seismic Profiling) experiment also a multi-azimuthal walkaway VSP survey took place. For the latter the source points were distributed along three profile lines centered radially around the borehole. For the central part up to 2.5 km away from the borehole, a hydraulic hammer source was used, which hits the ground for about 20 s with an linear increasing hit rate. For the far offset shots up to 5 km, explosive sources were used. The wavefield of both source types was recorded in the borehole using an array of 15 three-component receivers with a geophone spacing of 10 m. This array was deployed at 7 different depth levels during the survey. At the same time the wavefield was also recorded at the surface by 180 standalone three-component receivers placed along each of the three up to 10 km long lines, as well as with a 3D array of single-component receivers in the central part of the survey area around the borehole. Here

  6. INTEGRATED POLARIZATION PROPERTIES OF 3C48, 3C138, 3C147, AND 3C286

    SciTech Connect

    Perley, R. A.; Butler, B. J. E-mail: BButler@nrao.edu

    2013-06-01

    We present the integrated polarization properties of the four compact radio sources 3C48, 3C138, 3C147, and 3C286, from 1 to 50 GHz, over a 30 yr time frame spanning 1982-2012. Using the polarized emission of Mars, we have determined that the position angle of the linearly polarized emission of 3C286 rises from 33 Degree-Sign at 8 GHz to 36 Degree-Sign at 45 GHz. There is no evidence for a change in the position angle over time. Using these values, the position angles of the integrated polarized emission from the other three sources are determined as a function of frequency and time. The fractional polarization of 3C286 is found to be slowly rising, at all frequencies, at a rate of {approx}0.015% yr{sup -1}. The fractional polarizations of 3C48, 3C138, and 3C147 are all slowly variable, with the variations correlated with changes in the total flux densities of these sources.

  7. Why graphene growth is very different on the C face than on the Si face of SiC: Insights from surface equilibria and the (3 ×3 )-3 C -SiC (1 ¯ ¯ ā) reconstruction

    NASA Astrophysics Data System (ADS)

    Nemec, Lydia; Lazarevic, Florian; Rinke, Patrick; Scheffler, Matthias; Blum, Volker

    2015-04-01

    We address the stability of the surface phases that occur on the C side of 3 C -SiC (1 ¯1 ¯1 ¯) at the onset of graphene formation. In this growth range, experimental reports reveal a coexistence of several surface phases. This coexistence can be explained by a Si-rich model for the unknown (3 ×3 ) reconstruction, the known (2 ×2 )C adatom phase, and the graphene-covered (2 ×2)C phase. By constructing an ab initio surface phase diagram using a van der Waals corrected density functional, we show that the formation of a well defined interface structure like the "buffer layer" on the Si side is blocked by Si-rich surface reconstructions.

  8. Variable-period surface-wave magnitudes: A rapid and robust estimator of seismic moments

    USGS Publications Warehouse

    Bonner, J.; Herrmann, R.; Benz, H.

    2010-01-01

    We demonstrate that surface-wave magnitudes (Ms), measured at local, regional, and teleseismic distances, can be used as a rapid and robust estimator of seismic moment magnitude (Mw). We used the Russell (2006) variable-period surface-wave magnitude formula, henceforth called Ms(VMAX), to estimate the Ms for 165 North American events with 3.2 surface-wave observed at a local or near-regional distance seismic station after a preliminary epicentral location has been formed. Therefore, it may be used to make rapid measurements of Mw, which are needed by government agencies for early warning systems.

  9. Soil depth mapping using seismic surface waves: Evaluation on eroded loess covered hillslopes

    NASA Astrophysics Data System (ADS)

    Bernardie, Severine; Samyn, Kevin; Cerdan, Olivier; Grandjean, Gilles

    2010-05-01

    The purposes of the multidisciplinary DIGISOIL project are the integration and improvement of in situ and proximal technologies for the assessment of soil properties and soil degradation indicators. Foreseen developments concern sensor technologies, data processing and their integration to applications of (digital) soil mapping (DSM). Among available techniques, the seismic one is, in this study, particularly tested for characterising soil vulnerability to erosion. The spectral analysis of surface waves (SASW) method is an in situ seismic technique used for evaluation of the stiffnesses (G) and associated depth in layered systems. A profile of Rayleigh wave velocity versus frequency, i.e., the dispersion curve, is calculated from each recorded seismogram before to be inverted to obtain the vertical profile of shear wave velocity Vs. Then, the soil stiffness can easily be calculated from the shear velocity if the material density is estimated, and the soil stiffness as a function of depth can be obtained. This last information can be a good indicator to identify the soil bedrock limit. SASW measurements adapted to soil characterisation is proposed in the DIGISOIL project, as it produces in an easy and quick way a 2D map of the soil. This system was tested for the digital mapping of the depth of loamy material in a catchment of the European loess belt. The validation of this methodology has been performed with the realisation of several acquisitions along the seismic profiles: - Several boreholes were drilled until the bedrock, permitting to get the geological features of the soil and the depth of the bedrock; - Several laboratory measurements of various parameters were done on samples taken from the boreholes at various depths, such as dry density, solid density, and water content; - Dynamic penetration tests were also conducted along the seismic profile, until the bedrock is attained. Some empirical correlations between the parameters measured with laboratory tests

  10. Evaluation of potential surface rupture and review of current seismic hazards program at the Los Alamos National Laboratory. Final report

    SciTech Connect

    Not Available

    1991-12-09

    This report summarizes the authors review and evaluation of the existing seismic hazards program at Los Alamos National Laboratory (LANL). The report recommends that the original program be augmented with a probabilistic analysis of seismic hazards involving assignment of weighted probabilities of occurrence to all potential sources. This approach yields a more realistic evaluation of the likelihood of large earthquake occurrence particularly in regions where seismic sources may have recurrent intervals of several thousand years or more. The report reviews the locations and geomorphic expressions of identified fault lines along with the known displacements of these faults and last know occurrence of seismic activity. Faults are mapped and categorized into by their potential for actual movement. Based on geologic site characterization, recommendations are made for increased seismic monitoring; age-dating studies of faults and geomorphic features; increased use of remote sensing and aerial photography for surface mapping of faults; the development of a landslide susceptibility map; and to develop seismic design standards for all existing and proposed facilities at LANL.

  11. Quantifying and modeling Quaternary surface deformation in the New Madrid seismic zone, Central U.S

    NASA Astrophysics Data System (ADS)

    Magnani, M.; Boyd, O. S.

    2010-12-01

    Nearly a decade of geodetic monitoring in the New Madrid seismic zone (Central U.S.) indicates very low rates of surface deformation, which appear to be inconsistent with the return periods of large earthquakes in this region. To explore this apparent paradox, we quantify the Quaternary deformation associated with buried faults beneath the Mississippi embayment using high resolution seismic reflection data and model the geodetic data assuming post 1811-1812 earthquake effects and steady-state loading. Newly acquired marine reflection data across the Cottonwood Grove dextral strike-slip fault imaged two main vertical faults ~5 km apart displacing the unconsolidated sediments of the Mississippi Embayment, from the Paleozoic to the river deposits. At the two faults, the base of the Quaternary alluvium, which is Wisconsian in age in this region, is vertically displaced by 38 m and 30 m respectively, with an up-to-the-east sense of movement in both cases. Instrumental seismicity along the Cottonwood Grove fault ranges between depths of 5-25 km, and illuminates a single vertical plane extending into the upper and middle crust. Focal mechanisms along the fault indicate a predominantly horizontal sense of motion with a rake of about 5 degrees. This suggests that the vertical deformation observed along the seismic profile could imply a horizontal offset of almost 800 m, which leads to a slip rate of about 4.5 mm/yr. We model geodetic data assuming steady-state creep on lower crustal faults within the New Madrid seismic zone subject to various boundary conditions, including plate boundary stresses to the sides and from below. We also consider surface deformation resulting from viscoelastic relaxation in the lower crust/upper mantle after the 1811-1812 earthquakes. Our best fitting preliminary model, 1.5 mm/yr of slip imposed across a discontinuity along the downdip extension of the reverse-slip Reelfoot fault, can explain 43% of the variance in the geodetic observations. In

  12. Multi-parameter Full-waveform Inversion for Acoustic VTI Medium with Surface Seismic Data

    NASA Astrophysics Data System (ADS)

    Cheng, X.; Jiao, K.; Sun, D.; Huang, W.; Vigh, D.

    2013-12-01

    Full-waveform Inversion (FWI) attracts wide attention recently in oil and gas industry as a new promising tool for high resolution subsurface velocity model building. While the traditional common image point gather based tomography method aims to focus post-migrated data in depth domain, FWI aims to directly fit the observed seismic waveform in either time or frequency domain. The inversion is performed iteratively by updating the velocity fields to reduce the difference between the observed and the simulated data. It has been shown the inversion is very sensitive to the starting velocity fields, and data with long offsets and low frequencies is crucial for the success of FWI to overcome this sensitivity. Considering the importance of data with long offsets and low frequencies, in most geologic environment, anisotropy is an unavoidable topic for FWI especially at long offsets, since anisotropy tends to have more pronounced effects on waves traveled for a great distance. In VTI medium, this means more horizontal velocity will be registered in middle-to-long offset data, while more vertical velocity will be registered in near-to-middle offset data. Up to date, most of real world applications of FWI still remain in isotropic medium, and only a few studies have been shown to account for anisotropy. And most of those studies only account for anisotropy in waveform simulation, but not invert for those anisotropy fields. Multi-parameter inversion for anisotropy fields, even in VTI medium, remains as a hot topic in the field. In this study, we develop a strategy for multi-parameter FWI for acoustic VTI medium with surface seismic data. Because surface seismic data is insensitivity to the delta fields, we decide to hold the delta fields unchanged during our inversion, and invert only for vertical velocity and epsilon fields. Through parameterization analysis and synthetic tests, we find that it is more feasible to invert for the parameterization as vertical and horizontal

  13. Models of crustal thickness for South America from seismic refraction, receiver functions and surface wave tomography

    NASA Astrophysics Data System (ADS)

    Assumpção, Marcelo; Feng, Mei; Tassara, Andrés; Julià, Jordi

    2013-12-01

    An extensive compilation of crustal thicknesses is used to develop crustal models in continental South America. We consider point crustal thicknesses from seismic refraction experiments, receiver function analyses, and surface-wave dispersion. Estimates of crustal thickness derived from gravity anomalies were only included along the continental shelf and in some areas of the Andes to fill large gaps in seismic coverage. Two crustal models were developed: A) by simple interpolation of the point estimates, and B) our preferred model, based on the same point estimates, interpolated with surface-wave tomography. Despite gaps in continental coverage, both models reveal interesting crustal thickness variations. In the Andean range, the crust reaches 75 km in Southern Peru and the Bolivian Altiplano, while crustal thicknesses seem to be close to the global continental average (~ 40 km) in Ecuador and southern Colombia (despite high elevations), and along the southern Andes of Chile-Argentina (elevation lower than 2000 m). In the stable continental platform the average thickness is 38 ± 5 km (1-st. deviation) and no systematic differences are observed among Archean-Paleoproterozoic cratons, NeoProterozoic fold belts, and low-altitude intracratonic sedimentary basins. An exception is the Borborema Province (NE Brazil) with crust ~ 30-35 km thick. Narrow belts surrounding the cratons are suggested in central Brazil, parallel to the eastern and southern border of the Amazon craton, and possibly along the TransBrasiliano Lineament continuing into the Chaco basin, where crust thinner than 35 km is observed. In the sub-Andean region, between the mid-plate cratons and the Andean cordillera, the crust tends to be thinner (~ 35 km) than the average crust in the stable platform, a feature possibly inherited from the old pre-Cambrian history of the continent. We expect that these crustal models will be useful for studies of isostasy, dynamic topography, and crustal evolution of the

  14. Induced Seismicity Monitoring System

    NASA Astrophysics Data System (ADS)

    Taylor, S. R.; Jarpe, S.; Harben, P.

    2014-12-01

    There are many seismological aspects associated with monitoring of permanent storage of carbon dioxide (CO2) in geologic formations. Many of these include monitoring underground gas migration through detailed tomographic studies of rock properties, integrity of the cap rock and micro seismicity with time. These types of studies require expensive deployments of surface and borehole sensors in the vicinity of the CO2 injection wells. Another problem that may exist in CO2 sequestration fields is the potential for damaging induced seismicity associated with fluid injection into the geologic reservoir. Seismic hazard monitoring in CO2 sequestration fields requires a seismic network over a spatially larger region possibly having stations in remote settings. Expensive observatory-grade seismic systems are not necessary for seismic hazard deployments or small-scale tomographic studies. Hazard monitoring requires accurate location of induced seismicity to magnitude levels only slightly less than that which can be felt at the surface (e.g. magnitude 1), and the frequencies of interest for tomographic analysis are ~1 Hz and greater. We have developed a seismo/acoustic smart sensor system that can achieve the goals necessary for induced seismicity monitoring in CO2 sequestration fields. The unit is inexpensive, lightweight, easy to deploy, can operate remotely under harsh conditions and features 9 channels of recording (currently 3C 4.5 Hz geophone, MEMS accelerometer and microphone). An on-board processor allows for satellite transmission of parameter data to a processing center. Continuous or event-detected data is kept on two removable flash SD cards of up to 64+ Gbytes each. If available, data can be transmitted via cell phone modem or picked up via site visits. Low-power consumption allows for autonomous operation using only a 10 watt solar panel and a gel-cell battery. The system has been successfully tested for long-term (> 6 months) remote operations over a wide range

  15. Dynamic weakening of serpentinite gouges and bare surfaces at seismic slip rates

    PubMed Central

    Proctor, B P; Mitchell, T M; Hirth, G; Goldsby, D; Zorzi, F; Platt, J D; Di Toro, G

    2014-01-01

    To investigate differences in the frictional behavior between initially bare rock surfaces of serpentinite and powdered serpentinite (“gouge”) at subseismic to seismic slip rates, we conducted single-velocity step and multiple-velocity step friction experiments on an antigorite-rich and lizardite-rich serpentinite at slip rates (V) from 0.003 m/s to 6.5 m/s, sliding displacements up to 1.6 m, and normal stresses (σn) up to 22 MPa for gouge and 97 MPa for bare surfaces. Nominal steady state friction values (μnss) in gouge at V = 1 m/s are larger than in bare surfaces for all σn tested and demonstrate a strong σn dependence; μnss decreased from 0.51 at 4.0 MPa to 0.39 at 22.4 MPa. Conversely, μnss values for bare surfaces remained ∼0.1 with increasing σn and V. Additionally, the velocity at the onset of frictional weakening and the amount of slip prior to weakening were orders of magnitude larger in gouge than in bare surfaces. Extrapolation of the normal stress dependence for μnss suggests that the behavior of antigorite gouge approaches that of bare surfaces at σn ≥ 60 MPa. X-ray diffraction revealed dehydration reaction products in samples that frictionally weakened. Microstructural analysis revealed highly localized slip zones with melt-like textures in some cases gouge experiments and in all bare surfaces experiments for V ≥ 1 m/s. One-dimensional thermal modeling indicates that flash heating causes frictional weakening in both bare surfaces and gouge. Friction values for gouge decrease at higher velocities and after longer displacements than bare surfaces because strain is more distributed. Key Points Gouge friction approaches that of bare surfaces at high normal stress Dehydration reactions and bulk melting in serpentinite in < 1 m of slip Flash heating causes dynamic frictional weakening in gouge and bare surfaces PMID:26167425

  16. Evidence of historical seismic surface ruptures along the Sahel fault (Algeria) from paleoseismological investigations

    NASA Astrophysics Data System (ADS)

    Heddar, Aicha; Authemayou, Christine; Yelles, Abdelkarim; Djellit, Hamou; Déverchère, Jacques; Boudiaf, Azzedine; Van Vliet-Lanoë, Brigitte; Gharbi, Sofiane

    2013-04-01

    The Sahel ridge, located west of Algiers is a part of the Tellian Atlas (northern Algeria) domain which is formed by subsiding basins, fold and thrust geological structures stretching from East to West on the southern shore of the Mediterranean Sea. This area is characterized by an active tectonic attested by an important seismicity. Among these active structures, the Sahel anticline is considered as an ENE-WSW fault-propagation fold associated with a north-west dipping thrust. Its proximity with the urbanized zone of Algiers makes this structure a potential source of destructive earthquakes that could hit the capital city. The Algerian seismic catalog mentions that the region of Algiers has experienced in the historical period several moderate to large damaging earthquakes particularly those which occurred on 1365 A.D and 1716 A.D causing many deaths and damages in the city of Algiers. Even if, it was observed that sometimes events are followed by a large sequence of aftershocks suggesting high magnitudes, no surface faulting has been observed in the region and no event has been associated with a specific structure. We proceed to the first paleoseismologic investigation on the Sahel ridge in the purpose to detect paleo-ruptures related to active faulting and to date them in an attempt to complement the seismologic catalog of the region and to attribute known historical seismic events to the Sahel structure activity. From our first investigations in the area, a first trench was excavated across bending-moment normal faults induced by flexural slip folding in the hanging wall of the Sahel anticline thrust ramp. Paleoseismological analyses evidence eight rupture events affecting colluvial deposits. 14C dating indicates that these events are very young, six of them being younger than 778 A.D. The first sedimentary record indicates two ruptures before 1211 A.D., i.e. older than the first historical earthquake documented in the region. Three events have age range

  17. Homogenization of seismic surface wave profiling in highly heterogeneous improved ground

    NASA Astrophysics Data System (ADS)

    Lin, C.; Chien, C.

    2012-12-01

    Seismic surface wave profiling is gaining popularity in engineering practice for determining shear-wave velocity profile since the two-station SASW (Spectral Analysis of Surface Wave) was introduced. Recent developments in the multi-station approach (Multi-station Analysis of Surface Wave, MASW) result in several convenient commercial tools. Unlike other geophysical tomography methods, the surface wave method is essentially a 1-D method assuming horizontally-layered medium. Nevertheless, MASW is increasingly used to map lateral variation of S-wave velocity by multiple surveys overlooking the effect of lateral heterogeneity. MASW typically requires long receiver spread in order to have enough depth coverage. The accuracy and lateral resolution of 2-D S-wave velocity imaging by surface wave is not clear. Many geotechnical applications involves lateral variation in a scale smaller than the geophone spread and wave length. For example, soft ground is often improved to increase strength and stiffness by methods such as jet grouting and stone column which result in heterogeneous ground with improved columns. Experimental methods (Standard Penetration Test, sampling and laboratory testing, etc.) used to assess such ground improvement are subjected to several limitations such as small sampling volume, time-consuming, and cost ineffectiveness. It's difficult to assess the average property of the improved ground and the actual replacement ratio of ground improvement. The use of seismic surface wave method for such a purpose seems to be a good alternative. But what MASW measures in such highly heterogeneous improved ground remains to be investigated. This study evaluated the feasibility of MASW in highly heterogeneous ground with improved columns and investigated the homogenization of shear wave velocity measured by MASW. Field experiments show that MASW testing in such a composite ground behaves similar to testing in horizontally layered medium. It seems to measure some sort

  18. Seismic surface-wave prospecting methods for sinkhole hazard assessment along the Dead Sea shoreline

    NASA Astrophysics Data System (ADS)

    Ezersky, M.; Bodet, L.; Al-Zoubi, A.; Camerlynck, C.; Dhemaied, A.; Galibert, P.-Y.; Keydar, S.

    2012-04-01

    waves generation and picking issues in shear-wave refraction seismic methods. As an alternative, indirect estimation of Vs can then be proposed thanks to surface-wave dispersion measurements and inversion, an emerging seismic prospecting method for near-surface engineering and environment applications. Surface-wave prospecting methods have thus been proposed to address the sinkholes development processes along the Dead Sea shorelines. Two approaches have been used: (1) Vs mapping has been performed to discriminate soft and hard zones within salt layers, after calibration of inverted Vs near boreholes. Preliminarily, soft zones, associated with karstified salt, were characterized by Vs values lower than 1000 m/s, whereas hard zones presented values greater than 1400 m/s (will be specified during following studies); (2) roll along acquisition and dispersion stacking has been performed to achieve multi-modal dispersion measurements along linear profiles. Inverted pseudo-2D Vs sections presented low Vs anomalies in the vicinity of existing sinkholes and made it possible to detect loose sediment associated with potential sinkholes occurrences. Acknowledgements This publication was made possible through support provided by the U.S. Agency for International Development (USAID) and MERC Program under terms of Award No M27-050.

  19. Imaging Near-Surface Controls on Hot Spring Expression Using Shallow Seismic Refraction in Yellowstone National Park

    NASA Astrophysics Data System (ADS)

    Price, A. N.; Lindsey, C.; Fairley, J. P., Jr.; Larson, P. B.

    2015-12-01

    We used shallow seismic refraction to image near-surface materials in the vicinity of a small group of hot springs, located in the Morning Mist Springs area of Lower Geyser Basin, Yellowstone National Park, Wyoming. Seismic velocities in the area surveyed range from a low of 0.3 km/s to a high of approximately 2.5 km/s. The survey results indicate an irregular surface topography overlain by silty sediments. The observed seismic velocities are consistent with a subsurface model in which sorted sands and gravels, probably outwash materials from the Pinedale glaciation, are overlain by silts and fine sands deposited in the flat-lying areas of the Morning Springs area. These findings are supported by published geologic maps of the area and well logs from a nearby borehole. The near-surface materials appear to be saturated with discharging hydrothermal fluids of varying temperature, and interbedded with semi-lithified geothermal deposits (sinter). We hypothesize that the relatively low-conductivity deposits of fines at the surface may serve to confine a shallow, relatively low-temperature (sub-boiling) hydrothermal aquifer, and that the distribution of sinter in the shallow subsurface plays an important role in determining the geometry of hydrothermal discharge (hot springs) at the land surface. Few studies of the shallow controls on hot spring expression exist for the Yellowstone caldera, and the present study therefore offers a unique glimpse into near-subsurface fluid flow controls.

  20. Complex source mechanisms of mining-induced seismic events - implications for surface effects

    NASA Astrophysics Data System (ADS)

    Orlecka-Sikora, B.; Cesca, S.; Lasocki, S.; Rudzinski, L.; Lizurek, L.; Wiejacz, P.; Urban, P.; kozlowska, M.

    2012-04-01

    The seismicity of Legnica-Głogów Copper District (LGCD) is induced by mining activities in three mines: Lubin, Rudna and Polkowice-Sieroszowice. Ground motion caused by strong tremors might affect local infrastructure. "Żelazny Most" tailings pond, the biggest structure of this type in Europe, is here under special concern. Due to surface objects protection, Rudna Mine has been running ground motion monitoring for several years. From June 2010 to June 2011 unusually strong and extensive surface impact has been observed for 6 mining tremors induced in one of Rudna mining sections. The observed peak ground acceleration (PGA) for both horizontal and vertical component were in or even beyond 99% confidence interval for prediction. The aim of this paper is analyze the reason of such unusual ground motion. On the basis of registrations from Rudna Mine mining seismological network and records from Polish Seismological Network held by the Institute of Geophysics Polish Academy of Sciences (IGF PAN), the source mechanisms of these 6 tremors were calculated using a time domain moment tensor inversion. Furthermore, a kinematic analysis of the seismic source was performed, in order to determine the rupture planes orientations and rupture directions. These results showed that in case of the investigated tremors, point source models and shear fault mechanisms, which are most often assumed in mining seismology, are invalid. All analyzed events indicate extended sources with non-shear mechanism. The rapture planes have small dip angles and the rupture starts at the tremors hypocenter and propagates in the direction opposite to the plane dip. The tensional component plays here also big role. These source mechanisms well explain such observed strong ground motion, and calculated synthetic PGA values well correlates with observed ones. The relationship between mining tremors were also under investigation. All subsequent tremors occurred in the area of increased stress due to

  1. Annual Variation of Seismicity due to Surface Loads in Normal Fault Systems in Southern Tibet

    NASA Astrophysics Data System (ADS)

    Tian, Y.; Luo, Y.; Li, Y.; Wang, X.; Zhang, J.

    2014-12-01

    It had been found that there are seasonal variations of seismicity related to surface hydrology at Main Himalaya Thrust (MHT) fault. In this work, we analyzed the historical micro-earthquakes recorded by China Digital Seismograph Network (CSDN) in normal faulting systems in southern Tibet, to test whether such a phenomenon exist here and to figure out the possible modulation mechanism. There are several N-S striking normal fault systems (e.g. Yadong-Gulu, Shenza-Dingjie rifts) across the southern Tibetan plateau, which are supposed to accommodate the crust extension induced by Indo-Eurasia collision. The quake catalog covers the time span of 2008-2014. All quake events are relocated using the double-differencing method. The catalog was then declustered using CLUSTER2000 (http://earthquake.usgs.gov/research/software/). The declustered catalog was then averaged for one-month period. The monthly catalog shows that the number of earthquake is maximum during the winter months (from January to March), although the maximum values do not agree for individual years (Fig. 1). Such a variation is similar to that found at MHT. Contrary to the situation at MHT (thrust fault), we found it might be explained directly by surface mass redistributions. The contemporary continuous GPS observations confirm that Tibetan plateau crust moves up and down periodically and reaches its lowest position in summer under the surface hydrological load. According to the Coulomb failure criterion (S=τ-μ(σn-pf) , where S is Coulomb Stress, σn is normal stress, τ is shear stress), an increase of mass load in summer in Tibet will cause an increase in normal stress at the (gently dipping) fault plane and accordingly a decrease in Coulomb stress, which thus inhibits the occurrence of quakes on those normal fault planes.

  2. Seismic structure of the southern Apennines as revealed by waveform modelling of regional surface waves

    NASA Astrophysics Data System (ADS)

    Ökeler, Ahmet; Gu, Yu Jeffrey; Lerner-Lam, Arthur; Steckler, Michael S.

    2009-09-01

    We investigate the crust and upper-mantle structures beneath the southern Apennine mountain chain using three-component seismograms from the Calabria-Apennine-Tyrrhenian/Subduction-Collision-Accretion Network (CAT/SCAN) array. Surface wave waveforms from three moderate-sized (Mw > 5.0) regional earthquakes are modelled using multiple frequencies (0.03-0.06 and 0.05-0.2 Hz) and both forward and linearized-inversion algorithms. Our best-fitting shear velocity models clearly reflect the major tectonic units where, for example, the average seismic structure at depths above 50 km beneath Apulia is substantially faster than beneath the Apennine mountain chain. We identify a prominent low-velocity channel under the mountain belt at depths below ~25-30 km and a secondary low-velocity zone at 6-12 km depth near Mt Vulture (a once active volcano). Speed variations between Love and Rayleigh waves provide further constraints on the fabric and dynamic processes. Our analysis indicates that the crustal low-velocity zones are highly anisotropic (maximum 14 per cent) and allow transversely polarized shear waves to travel faster than vertically polarized shear waves. The upper crustal anomaly reveals a layer of highly deformed rocks caused by past collisions and by the active normal faults cutting across the thrust sheets, whereas hot mantle upwelling may be responsible for a high-temperature, partially molten lower crust beneath the southern Apennines.

  3. On using surface-source downhole-receiver logging to determine seismic slownesses

    USGS Publications Warehouse

    Boore, D.M.; Thompson, E.M.

    2007-01-01

    We present a method to solve for slowness models from surface-source downhole-receiver seismic travel-times. The method estimates the slownesses in a single inversion of the travel-times from all receiver depths and accounts for refractions at layer boundaries. The number and location of layer interfaces in the model can be selected based on lithologic changes or linear trends in the travel-time data. The interfaces based on linear trends in the data can be picked manually or by an automated algorithm. We illustrate the method with example sites for which geologic descriptions of the subsurface materials and independent slowness measurements are available. At each site we present slowness models that result from different interpretations of the data. The examples were carefully selected to address the reliability of interface-selection and the ability of the inversion to identify thin layers, large slowness contrasts, and slowness gradients. Additionally, we compare the models in terms of ground-motion amplification. These plots illustrate the sensitivity of site amplifications to the uncertainties in the slowness model. We show that one-dimensional site amplifications are insensitive to thin layers in the slowness models; although slowness is variable over short ranges of depth, this variability has little affect on ground-motion amplification at frequencies up to 5 Hz.

  4. Active seismic experiment

    NASA Technical Reports Server (NTRS)

    Kovach, R. L.; Watkins, J. S.; Talwani, P.

    1972-01-01

    The Apollo 16 active seismic experiment (ASE) was designed to generate and monitor seismic waves for the study of the lunar near-surface structure. Several seismic energy sources are used: an astronaut-activated thumper device, a mortar package that contains rocket-launched grenades, and the impulse produced by the lunar module ascent. Analysis of some seismic signals recorded by the ASE has provided data concerning the near-surface structure at the Descartes landing site. Two compressional seismic velocities have so far been recognized in the seismic data. The deployment of the ASE is described, and the significant results obtained are discussed.

  5. Seismic velocity structure of the crust and shallow mantle of the Central and Eastern United States by seismic surface wave imaging

    USGS Publications Warehouse

    Pollitz, Fred; Mooney, Walter D.

    2016-01-01

    Seismic surface waves from the Transportable Array of EarthScope's USArray are used to estimate phase velocity structure of 18 to 125 s Rayleigh waves, then inverted to obtain three-dimensional crust and upper mantle structure of the Central and Eastern United States (CEUS) down to ∼200 km. The obtained lithosphere structure confirms previously imaged CEUS features, e.g., the low seismic-velocity signature of the Cambrian Reelfoot Rift and the very low velocity at >150 km depth below an Eocene volcanic center in northwestern Virginia. New features include high-velocity mantle stretching from the Archean Superior Craton well into the Proterozoic terranes and deep low-velocity zones in central Texas (associated with the late Cretaceous Travis and Uvalde volcanic fields) and beneath the South Georgia Rift (which contains Jurassic basalts). Hot spot tracks may be associated with several imaged low-velocity zones, particularly those close to the former rifted Laurentia margin.

  6. Conceptual Design and Architecture of Mars Exploration Rover (MER) for Seismic Experiments Over Martian Surfaces

    NASA Astrophysics Data System (ADS)

    Garg, Akshay; Singh, Amit

    2012-07-01

    Keywords: MER, Mars, Rover, Seismometer Mars has been a subject of human interest for exploration missions for quite some time now. Both rover as well as orbiter missions have been employed to suit mission objectives. Rovers have been preferentially deployed for close range reconnaissance and detailed experimentation with highest accuracy. However, it is essential to strike a balance between the chosen science objectives and the rover operations as a whole. The objective of this proposed mechanism is to design a vehicle (MER) to carry out seismic studies over Martian surface. The conceptual design consists of three units i.e. Mother Rover as a Surrogate (Carrier) and Baby Rovers (two) as seeders for several MEMS-based accelerometer / seismometer units (Nodes). Mother Rover can carry these Baby Rovers, having individual power supply with solar cells and with individual data transmission capabilities, to suitable sites such as Chasma associated with Valles Marineris, Craters or Sand Dunes. Mother rover deploys these rovers in two opposite direction and these rovers follow a triangulation pattern to study shock waves generated through firing tungsten carbide shells into the ground. Till the time of active experiments Mother Rover would act as a guiding unit to control spatial spread of detection instruments. After active shock experimentation, the babies can still act as passive seismometer units to study and record passive shocks from thermal quakes, impact cratering & landslides. Further other experiments / payloads (XPS / GAP / APXS) can also be carried by Mother Rover. Secondary power system consisting of batteries can also be utilized for carrying out further experiments over shallow valley surfaces. The whole arrangement is conceptually expected to increase the accuracy of measurements (through concurrent readings) and prolong life cycle of overall experimentation. The proposed rover can be customised according to the associated scientific objectives and further

  7. Cyclic spattering, seismic tremor, and surface fluctuation within a perched lava channel, Kīlauea Volcano

    USGS Publications Warehouse

    Patrick, M.R.; Orr, T.; Wilson, D.; Dow, D.; Freeman, R.

    2011-01-01

    In late 2007, a perched lava channel, built up to 45 m above the preexisting surface, developed during the ongoing eruption near Pu‘u ‘Ō‘ō cone on Kīlauea Volcano’s east rift zone. The lava channel was segmented into four pools extending over a total of 1.4 km. From late October to mid-December, a cyclic behavior, consisting of steady lava level rise terminated by vigorous spattering and an abrupt drop in lava level, was commonly observed in pool 1. We use geologic observations, video, time-lapse camera images, and seismicity to characterize and understand this cyclic behavior. Spattering episodes occurred at intervals of 40–100 min during peak activity and involved small (5–10-m-high) fountains limited to the margins of the pool. Most spattering episodes had fountains which migrated downchannel. Each spattering episode was associated with a rapid lava level drop of about 1 m, which was concurrent with a conspicuous cigar-shaped tremor burst with peak frequencies of 4–5 Hz. We interpret this cyclic behavior to be gas pistoning, and this is the first documented instance of gas pistoning in lava well away from the deeper conduit. Our observations and data indicate that the gas pistoning was driven by gas accumulation beneath the visco-elastic component of the surface crust, contrary to other studies which attribute similar behavior to the periodic rise of gas slugs. The gas piston events typically had a gas mass of about 2,500 kg (similar to the explosions at Stromboli), with gas accumulation and release rates of about 1.1 and 5.7 kg s−1, respectively. The time-averaged gas output rate of the gas pistoning events accounted for about 1–2% of the total gas output rate of the east rift zone eruption.

  8. Resistivity and Seismic Surface Wave Tomography Results for the Nevşehir Kale Region: Cappadocia, Turkey

    NASA Astrophysics Data System (ADS)

    Coşkun, Nart; Çakır, Özcan; Erduran, Murat; Arif Kutlu, Yusuf

    2014-05-01

    The Nevşehir Kale region located in the middle of Cappadocia with approximately cone shape is investigated for existence of an underground city using the geophysical methods of electrical resistivity and seismic surface wave tomography together. Underground cities are generally known to exist in Cappadocia. The current study has obtained important clues that there may be another one under the Nevşehir Kale region. Two-dimensional resistivity and seismic profiles approximately 4-km long surrounding the Nevşehir Kale are measured to determine the distribution of electrical resistivities and seismic velocities under the profiles. Several high resistivity anomalies with a depth range 8-20 m are discovered to associate with a systematic void structure beneath the region. Because of the high resolution resistivity measurement system currently employed we were able to isolate the void structure from the embedding structure. Low seismic velocity zones associated with the high resistivity depths are also discovered. Using three-dimensional visualization techniques we show the extension of the void structure under the measured profiles.

  9. Sensor placement for the analysis of seismic surface waves: sources of error, design criterion and array design algorithms

    NASA Astrophysics Data System (ADS)

    Maranò, Stefano; Fäh, Donat; Lu, Yue M.

    2014-06-01

    Seismic surface waves can be measured by deploying an array of seismometers on the surface of the earth. The goal of such measurement surveys is, usually, to estimate the velocity of propagation and the direction of arrival of the seismic waves. In this paper, we address the issue of sensor placement for the analysis of seismic surface waves from ambient vibration wavefields. First, we explain in detail how the array geometry affects the mean-squared estimation error of parameters of interest, such as the velocity and direction of propagation, both at low and high signal-to-noise ratios (SNRs). Secondly, we propose a cost function suitable for the design of the array geometry with particular focus on the estimation of the wavenumber of both Love and Rayleigh waves. Thirdly, we present and compare several computational approaches to minimize the proposed cost function. Numerical experiments verify the effectiveness of our cost function and resulting array geometry designs, leading to greatly improved estimation performance in comparison to arbitrary array geometries, both at low and high SNR levels.

  10. New approach to detect seismic surface waves in 1Hz-sampled GPS time series.

    PubMed

    Houlié, N; Occhipinti, G; Blanchard, T; Shapiro, N; Lognonné, P; Murakami, M

    2011-01-01

    Recently, co-seismic seismic source characterization based on GPS measurements has been completed in near- and far-field with remarkable results. However, the accuracy of the ground displacement measurement inferred from GPS phase residuals is still depending of the distribution of satellites in the sky. We test here a method, based on the double difference (DD) computations of Line of Sight (LOS), that allows detecting 3D co-seismic ground shaking. The DD method is a quasi-analytically free of most of intrinsic errors affecting GPS measurements. The seismic waves presented in this study produced DD amplitudes 4 and 7 times stronger than the background noise. The method is benchmarked using the GEONET GPS stations recording the Hokkaido Earthquake (2003 September 25th, Mw = 8.3). PMID:22355563

  11. New approach to detect seismic surface waves in 1Hz-sampled GPS time series.

    PubMed

    Houlié, N; Occhipinti, G; Blanchard, T; Shapiro, N; Lognonné, P; Murakami, M

    2011-01-01

    Recently, co-seismic seismic source characterization based on GPS measurements has been completed in near- and far-field with remarkable results. However, the accuracy of the ground displacement measurement inferred from GPS phase residuals is still depending of the distribution of satellites in the sky. We test here a method, based on the double difference (DD) computations of Line of Sight (LOS), that allows detecting 3D co-seismic ground shaking. The DD method is a quasi-analytically free of most of intrinsic errors affecting GPS measurements. The seismic waves presented in this study produced DD amplitudes 4 and 7 times stronger than the background noise. The method is benchmarked using the GEONET GPS stations recording the Hokkaido Earthquake (2003 September 25th, Mw = 8.3).

  12. New approach to detect seismic surface waves in 1Hz-sampled GPS time series

    PubMed Central

    Houlié, N.; Occhipinti, G.; Blanchard, T.; Shapiro, N.; Lognonné, P.; Murakami, M.

    2011-01-01

    Recently, co-seismic seismic source characterization based on GPS measurements has been completed in near- and far-field with remarkable results. However, the accuracy of the ground displacement measurement inferred from GPS phase residuals is still depending of the distribution of satellites in the sky. We test here a method, based on the double difference (DD) computations of Line of Sight (LOS), that allows detecting 3D co-seismic ground shaking. The DD method is a quasi-analytically free of most of intrinsic errors affecting GPS measurements. The seismic waves presented in this study produced DD amplitudes 4 and 7 times stronger than the background noise. The method is benchmarked using the GEONET GPS stations recording the Hokkaido Earthquake (2003 September 25th, Mw = 8.3). PMID:22355563

  13. Comparison of P- and S-wave velocity profiles obtained from surface seismic refraction/reflection and downhole data

    USGS Publications Warehouse

    Williams, R.A.; Stephenson, W.J.; Odum, J.K.

    2003-01-01

    High-resolution seismic-reflection/refraction data were acquired on the ground surface at six locations to compare with near-surface seismic-velocity downhole measurements. Measurement sites were in Seattle, WA, the San Francisco Bay Area, CA, and the San Fernando Valley, CA. We quantitatively compared the data in terms of the average shear-wave velocity to 30-m depth (Vs30), and by the ratio of the relative site amplification produced by the velocity profiles of each data type over a specified set of quarter-wavelength frequencies. In terms of Vs30, similar values were determined from the two methods. There is <15% difference at four of the six sites. The Vs30 values at the other two sites differ by 21% and 48%. The relative site amplification factors differ generally by less than 10% for both P- and S-wave velocities. We also found that S-wave reflections and first-arrival phase delays are essential for identifying velocity inversions. The results suggest that seismic reflection/refraction data are a fast, non-invasive, and less expensive alternative to downhole data for determining Vs30. In addition, we emphasize that some P- and S-wave reflection travel times can directly indicate the frequencies of potentially damaging earthquake site resonances. A strong correlation between the simple S-wave first-arrival travel time/apparent velocity on the ground surface at 100 m offset from the seismic source and the Vs30 value for that site is an additional unique feature of the reflection/refraction data that could greatly simplify Vs30 determinations. ?? 2003 Elsevier Science B.V. All rights reserved.

  14. Seismic imaging of the upper mantle beneath the northern Central Andean Plateau: Implications for surface topography

    NASA Astrophysics Data System (ADS)

    Ward, K. M.; Zandt, G.; Beck, S. L.; Wagner, L. S.

    2015-12-01

    Extending over 1,800 km along the active South American Cordilleran margin, the Central Andean Plateau (CAP) as defined by the 3 km elevation contour is second only to the Tibetan Plateau in geographic extent. The uplift history of the 4 km high Plateau remains uncertain with paleoelevation studies along the CAP suggesting a complex, non-uniform uplift history. As part of the Central Andean Uplift and the Geodynamics of High Topography (CAUGHT) project, we use surface waves measured from ambient noise and two-plane wave tomography to image the S-wave velocity structure of the crust and upper mantle to investigate the upper mantle component of plateau uplift. We observe three main features in our S-wave velocity model including (1), a high velocity slab (2), a low velocity anomaly above the slab where the slab changes dip from near horizontal to a normal dip, and (3), a high-velocity feature in the mantle above the slab that extends along the length of the Altiplano from the base of the Moho to a depth of ~120 km with the highest velocities observed under Lake Titicaca. A strong spatial correlation exists between the lateral extent of this high-velocity feature beneath the Altiplano and the lower elevations of the Altiplano basin suggesting a potential relationship. Non-uniqueness in our seismic models preclude uniquely constraining this feature as an uppermost mantle feature bellow the Moho or as a connected eastward dipping feature extending up to 300 km in the mantle as seen in deeper mantle tomography studies. Determining if the high velocity feature represents a small lithospheric root or a delaminating lithospheric root extending ~300 km into the mantle requires more integration of observations, but either interpretation shows a strong geodynamic connection with the uppermost mantle and the current topography of the northern CAP.

  15. High-resolution shallow reflection seismic image and surface evidence of the Upper Tiber Basin active faults (Northern Apennines, Italy)

    USGS Publications Warehouse

    Donne, D.D.; Plccardi, L.; Odum, J.K.; Stephenson, W.J.; Williams, R.A.

    2007-01-01

    Shallow seismic reflection prospecting has been carried out in order to investigate the faults that bound to the southwest and northeast the Quaternary Upper Tiber Basin (Northern Apennines, Italy). On the northeastern margin of the basin a ??? 1 km long reflection seismic profile images a fault segment and the associated up to 100 meters thick sediment wedge. Across the southwestern margin a 0.5 km-long seismic profile images a 50-55??-dipping extensional fault, that projects to the scarp at the base of the range-front, and against which a 100 m thick syn-tectonic sediment wedge has formed. The integration of surface and sub-surface data allows to estimate at least 190 meters of vertical displacement along the fault and a slip rate around 0.25 m/kyr. Southwestern fault might also be interpreted as the main splay structure of regional Alto Tiberina extensional fault. At last, the 1917 Monterchi earthquake (Imax=X, Boschi et alii, 2000) is correlable with an activation of the southwestern fault, and thus suggesting the seismogenic character of this latter.

  16. Faulting apparently related to the 1994 Northridge, California, earthquake and possible co-seismic origin of surface cracks in Potrero Canyon, Los Angeles County, California

    USGS Publications Warehouse

    Catchings, R.D.; Goldman, M.R.; Lee, W.H.K.; Rymer, M.J.; Ponti, D.J.

    1998-01-01

    Apparent southward-dipping, reverse-fault zones are imaged to depths of about 1.5 km beneath Potrero Canyon, Los Angeles County, California. Based on their orientation and projection to the surface, we suggest that the imaged fault zones are extensions of the Oak Ridge fault. Geologic mapping by others and correlations with seismicity studies suggest that the Oak Ridge fault is the causative fault of the 17 January 1994 Northridge earthquake (Northridge fault). Our seismically imaged faults may be among several faults that collectively comprise the Northridge thrust fault system. Unusually strong shaking in Potrero Canyon during the Northridge earthquake may have resulted from focusing of seismic energy or co-seismic movement along existing, related shallow-depth faults. The strong shaking produced ground-surface cracks and sand blows distributed along the length of the canyon. Seismic reflection and refraction images show that shallow-depth faults may underlie some of the observed surface cracks. The relationship between observed surface cracks and imaged faults indicates that some of the surface cracks may have developed from nontectonic alluvial movement, but others may be fault related. Immediately beneath the surface cracks, P-wave velocities are unusually low (<400 m/sec), and there are velocity anomalies consistent with a seismic reflection image of shallow faulting to depths of at least 100 m. On the basis of velocity data, we suggest that unconsolidated soils (<800 m/sec) extend to depths of about 15 to 20 m beneath our datum (<25 m below ground surface). The underlying rocks range in velocity from about 1000 to 5000 m/sec in the upper 100 m. This study illustrates the utility of high-resolution seismic imaging in assessing local and regional seismic hazards.

  17. Multicomponent Body and Surface Wave Seismic Analysis using an Urban Land Streamer System: An Integrative Earthquake Hazards Assessment Approach

    NASA Astrophysics Data System (ADS)

    Gribler, G.; Liberty, L. M.

    2014-12-01

    We present earthquake site response results from a 48-channel multicomponent seismic land streamer and large weight drop system. We acquired data along a grid of city streets in western Idaho at a rate of a few km per day where we derived shear wave velocity profiles to a depth of 40-50 m by incorporating vertical and radial geophone signals to capture the complete elliptical Rayleigh wave motion. We also obtained robust p-wave reflection and refraction results by capturing the returned signals that arrive at non-vertical incidence angles that result from the high-velocity road surface layer. By integrating the derived shear wave velocity profiles with p-wave reflection results, we include depositional and tectonic boundaries from the upper few hundred meters into our analysis to help assess whether ground motions may be amplified by shallow bedrock. By including p-wave refraction information into the analysis, we can identify zones of high liquefaction potential by comparing shear wave and p-wave velocity (Vp/Vs) measurements relative to refraction-derived water table depths. The utilization of multicomponent land streamer data improves signal-noise levels over single component data with no additional field effort. The added multicomponent data processing step can be as simple as calculating the magnitude of the vector for surface wave and refraction arrivals or rotating the reflected signals to the maximum emergence angle based on near surface p-wave velocity information. We show example data from a number of Idaho communities where historical earthquakes have been recorded. We also present numerical models and systematic field tests that show the effects of a high velocity road surface layer in surface and body wave measurements. We conclude that multicomponent seismic information derived from seismic land streamers can provide a significant improvement in earthquake hazard assessment over a standard single component approach with only a small addition in

  18. Characterization of the Vajont landslide (North-Eastern Italy) by means of reflection and surface wave seismics

    NASA Astrophysics Data System (ADS)

    Petronio, Lorenzo; Boaga, Jacopo; Cassiani, Giorgio

    2016-05-01

    The mechanisms of the disastrous Vajont rockslide (North-Eastern Italy, October 9, 1963) have been studied in great detail over the past five decades. Nevertheless, the reconstruction of the rockslide dynamics still presents several uncertainties, including those related to the accurate estimation of the actual landslide mass. This work presents the results of a geophysical characterization of the Vajont landslide body in terms of material properties and buried geometry. Both aspects add new information to the existing dataset and will help a better understanding of the rockslide failure mechanisms and dynamics. In addition, some general considerations concerning the intricacies of landslide characterization can be drawn, with due attention to potential pitfalls. The employed techniques are: (i) high resolution P-wave reflection, (ii) high resolution SH-wave reflection, (iii) controlled source surface wave analysis. We adopted as a seismic source a vibrator both for P waves and SH waves, using vertical and horizontal geophones respectively. For the surface wave seismic survey we used a heavy drop-weight source and low frequency receivers. Despite the high noise level caused by the fractured conditions of the large rock body, a common situation in landslide studies, we managed to achieve a satisfying imaging quality of the landslide structure thanks to the large number of active channels, the short receiver interval and the test of appropriate seismic sources. The joint use of different seismic techniques help focus the investigation on the rock mass mechanical properties. Results are in good agreement with the available borehole data, the geological sections and the mechanical properties of the rockmass estimated by other studies. In general the proposed approach is likely to be applicable successfully to similar situations where scattering and other noise sources are a typical bottleneck to geophysical data acquisition on landslide bodies.

  19. Effect of the surface roughness on the seismic signal generated by a single rock impact: insight from laboratory experiments

    NASA Astrophysics Data System (ADS)

    Bachelet, Vincent; Mangeney, Anne; de Rosny, Julien; Toussaint, Renaud

    2016-04-01

    The seismic signal generated by rockfalls, landslides or avalanches is a unique tool to detect, characterize and monitor gravitational flow activity, with strong implication in terms of natural hazard monitoring. Indeed, as natural flows travel down the slope, they apply stresses on the ground, generating seismic waves in a wide frequency band. Our ultimate objective is to relate the granular flow properties to the generated signals that result from the different physical processes involved. We investigate here the more simple process: the impact of a single bead on a rough surface. Farin et al. [2015] have already shown theoretically and experimentally the existence of a link between the properties of an impacting bead (mass and velocity) on smooth surfaces, and the emitted signal (radiated elastic energy and mean frequency). This demonstrates that the single impactor properties can be deduced from the form of the emitted signal. We extend this work here by investigating the impact of single beads and gravels on rough and erodible surfaces. Experimentally, we drop glass and steel beads of diameters from 2 mm to 10 mm on a PMMA plate. The roughness of this last is obtained by gluing 3mm-diameter glass beads on one of its face. Free beads have been also added to get erodible beds. We track the dropped impactor motion, times between impacts and the generated acoustic waves using two fast cameras and 8 accelerometers. Cameras are used in addition to estimate the impactor rotation. We investigate the energy balance during the impact process, especially how the energy restitution varies as a function of the energy lost through acoustic waves. From these experiments, we clearly observe that even if more dissipative processes are involved (friction, grain reorganization, etc.), the single bead scaling laws obtained on smooth surfaces remain valid. A main result of this work is to quantify the fluctuations of the characteristic quantities such as the bounce angle, the

  20. High-resolution linear Radon transform and its applications in surface waves from ambient seismic noise data

    NASA Astrophysics Data System (ADS)

    Luo, Y.; Xu, Y.; Yang, Y.

    2010-12-01

    Ambient seismic noise tomography is widely used to determine crust and upper mantle surface-wave group/phase velocity structure. One of the key steps in this method is to calculate empirical Green’s function by cross-correlation from station-pairs. We demonstrate the effectiveness of high-resolution linear Radon transform (LRT) as a means of separating and reconstructing pure fundamental-mode dispersive Rayleigh-wave energy from empirical Green’s function. We first introduce high-resolution LRT methods and Rayleigh-wave mode separation using high-resolution LRT. Next, we apply high-resolution linear Radon transform to ambient seismic noise data of Dabieshan orogenic belt using 42-station data from the China National Seismic Network and surrounding global and regional stations between January 1 2008 and December 31 2009. Last, we compare Rayleigh-wave group/phase velocities from ambient noise correlations before and after mode separation by high-resolution LRT.

  1. A web-based platform for simulating seismic wave propagation in 3D shallow Earth models with DEM surface topography

    NASA Astrophysics Data System (ADS)

    Luo, Cong; Friederich, Wolfgang

    2016-04-01

    Realistic shallow seismic wave propagation simulation is an important tool for studying induced seismicity (e.g., during geothermal energy development). However over a long time, there is a significant problem which constrains computational seismologists from performing a successful simulation conveniently: pre-processing. Conventional pre-processing has often turned out to be inefficient and unrobust because of the miscellaneous operations, considerable complexity and insufficiency of available tools. An integrated web-based platform for shallow seismic wave propagation simulation has been built. It is aiming at providing a user-friendly pre-processing solution, and cloud-based simulation abilities. The main features of the platform for the user include: revised digital elevation model (DEM) retrieving and processing mechanism; generation of multi-layered 3D shallow Earth model geometry (the computational domain) with user specified surface topography based on the DEM; visualization of the geometry before the simulation; a pipeline from geometry to fully customizable hexahedral element mesh generation; customization and running the simulation on our HPC; post-processing and retrieval of the results over cloud. Regarding the computational aspect, currently the widely accepted specfem3D is chosen as the computational package; packages using different types of elements can be integrated as well in the future. According to our trial simulation experiments, this web-based platform has produced accurate waveforms while significantly simplifying and enhancing the pre-processing and improving the simulation success rate.

  2. Seismic wave propagation in a very permeable water-saturated surface layer

    NASA Astrophysics Data System (ADS)

    GéLi, Louis; Bard, Pierre-Yves; Schmitts, Denis P.

    1987-07-01

    According to Biot's (1956a, b) model, the presence of water plays an important role in the propagation of seismic waves in at least three different ways: (1) in an infinite medium, water saturation induces an attenuation that can be accounted for by a complex formulation of wave velocities, as in viscoelastic media; (2) at the boundaries of the saturated medium, pore pressure and water flux determine specific continuity conditions; and (3) there is a second compressional wave, called the P2 wave. In this paper, we discuss the latter two effects. Biot's model is presented first, with homogenization theory used to provide the numerical values of the different coefficients used in the model. In an infinite medium, the model is of practical interest when the frequency ƒ is about the same order of magnitude as a characteristic frequency noted ƒc, which depends on the properties of the constituents. This limits the application of Biot's model to a few particular fields in geophysics. In a layered medium, Biot's model has a wider scope in that it provides a tool for modeling fluid-solid interaction at the boundaries of the saturated medium. This is illustrated in our paper for the case of a very permeable water-saturated surface layer over an elastic half-space. Two examples are given; in the first example (rigid sands) we discuss the physics of the strongly attenuated P2 wave predicted by Biot, the amplitude of which becomes significant when the ƒ/ƒc ratio is about equal to or greater than 0.1. In the second example (soft unconsolidated sediments) the P2 wave is negligible, but the calculation of the complete wave field is required when the ƒ/ƒc ratio is about 0.01. There is no adequate equivalent single phase model that gives a correct estimation of the amplitude of the ground motion. In this case, we argue that the P2 wave is not important in itself, but Biot's model allows the description of the fluid-solid interaction at the water table; continuity of effective

  3. Do small surface strains in the New Madrid seismic zone reflect a physical process?

    NASA Astrophysics Data System (ADS)

    Boyd, O. S.; Zeng, Y.; Ramirez Guzman, L.; Smalley, R.

    2011-12-01

    We reevaluate GPS data over the decade from 2000-2010 and model the resulting observations with local deformation mechanisms: viscoelastic relaxation subsequent to the 1811-1812 New Madrid, MO, earthquakes and slip across deeply buried finite dislocations to represent interseismic strain accumulation. The reevaluation of the GPS data accounts for outliers, offsets in the position time-series, and annual and bi-annual seasonal variations. Site velocities are found from the slope of the position time-series and are relative to a reference, which is the stack of all position time-series for a given component. We find that relative site velocities have a standard deviation of about 0.2 mm/yr with uncertainties on the order of 0.1 to 0.2 mm/yr or more. Uncertainty is difficult to estimate directly because the random walk component of noise, which contributes most to uncertainty in long geodetic time series, cannot be distinguished from the flicker and white noise components. Multiple models can account for some of the variance in the GPS data. A viscoelastic response of the crust from the 7 February 1812 earthquake on the Reelfoot fault can account for 41% of the variance in the data. We perform an F-test and find that such a model has a 99% chance of being better able to match the data than does a null hypothesis. In this model, viscosity and slip are directly correlated such that increasing the viscosity by an order of magnitude requires an increase in slip by an order of magnitude to generate the same surface deformation. A viscoelastic response due to an earthquake on the Cottonwood Grove fault does not significantly improve our ability to model the data, but the lack of significance may be partly due to data limitations. Alternatively, a lower crustal right-lateral dislocation along the Cottonwood Grove fault slipping between 2 and 3 mm/yr from 20 to 40 km depth can account for 25% of the variance and has a 70% chance of being better able to match the data than

  4. Seafloor surface processes and subsurface paleo-channel unconformities mapped using multi-channel seismic and multi-beam sonar data from the Galicia 3D seismic experiment.

    NASA Astrophysics Data System (ADS)

    Gibson, J. C.; Shillington, D. J.; Sawyer, D. S.; Jordan, B.; Morgan, J. K.; Ranero, C.; Reston, T. J.

    2015-12-01

    In this study we use geophysical methods, stratigraphic relationships, and coring/drilling leg results to assess possible controls on deep-sea channel formation in order to further constrain paleo-channel (PC) and associated unconformity timing/source processes. A series of cut and fill PC are mapped in 3D multi-channel seismic (MCS) data and compared with multi-beam (MB) sonar bathymetry/backscatter data collected during the Galicia 3D survey with the R/V Marcus G. Langseth (2013). The MCS data were collected using four 6 km streamers spaced at 200 m resulting in 25 m x 25 m common mid-point bins within the ~67 km x 20 km 3D volume. The MB data were collected at an average depth of ~4900 m with a constrained swath width of 4.5 km resulting in 11.25x overlap while enabling 25-m bathymetry and 10-m backscatter grids. The PC lie below the mouth of a submarine canyon at the edge of the Galicia abyssal plain and cut pre/syn-rift sediments; they are bound by a rift block to the north and paleo-levees to the south (maximum height of ~180m). From drilling results, the most recent PC is late Miocene in age. In this study, four PC are traced into the basin as unconformities. Several of the PC/unconformities are tentatively correlated with previously interpreted Pyrenean orogeny/compressional Miocene/Oligocene tectonic events. However, one PC/unconformity within this interval has not been previously interpreted. In order test the hypothesis that the unconformities are the result of a significant change in base level indicated by a low shale/sand (SS) ratio, we use seismic surface attributes to calculate the SS ratio and trace the horizontal extent of the unconformities. Additionally, the MB/MCS seafloor morphology reveals sedimentary waves outboard of the canyon mouth. We use backscatter data to compare the extent of recent processes (e.g., Pleistocene glaciation/de-glaciation) with the unconformities by mapping the surface/shallow subsurface SS ratio (volume scattering).

  5. Near-surface S-wave velocity measured with six-degree-of-freedom seismic sensor Rotaphone

    NASA Astrophysics Data System (ADS)

    Malek, Jiri; Brokesova, Johana

    2015-04-01

    An essential parameter in seismic engineering is the near-surface S-wave velocity. Rotaphone, a six-degree-of-freedom seismic sensor can be used with advantage to retrieve it from collocated rotational and translational measurements. Rotaphone consists of highly sensitive geophones connected to a conjoint datalogger. The geophones are mounted in parallel pairs to a rigid (metal) ground-based frame. The instrument is designed to measure short-period translational ground motion (velocity) and, in addition, differential motion between the paired geophones. The records of those differential motions are used to obtain rotational components. In-situ calibration of individual geophones is performed simultaneously with each measurement, which enables to reach high sensitivity and accuracy of rotational measurements. In our method we utilize seismic waves produced by anthropogenic source - a generator of S waves and rotational ground motions. The generator contains a fixed part (anchored to the ground), a revolving part and a braking mechanism for immediate braking of the rotational part, in which rotational seismic motions are generated by immediately stopping the revolving part, whereby energy is transmitted into the rock massive. The generator produces repeatedly identical source pulses. Due to identity of the source pulses, we can suppress noise by means of stacking data from many generator actions and thus increase the depth range and resolution. The phase velocity retrieval is based on matching relevant acceleration and rotation rate components. Thanks to a near-source distance and high-frequency content of the source pulses, well-known equations for plane-wave approximation must be replaced by more adequate equations relating the individual rotation rate components to the translational ones. These equations are derived under an assumption of spherical wave. The resulting S-wave phase velocity is compared to the value obtained by standard profile measurements. The

  6. Near-surface, marine seismic-reflection data defines potential hydrogeologic confinement bypass in a tertiary carbonate aquifer, southeastern Florida

    USGS Publications Warehouse

    Cunningham, Kevin J.; Walker, Cameron; Westcott, Richard L.

    2012-01-01

    Approximately 210 km of near-surface, high-frequency, marine seismic-reflection data were acquired on the southeastern part of the Florida Platform between 2007 and 2011. Many high-resolution, seismic-reflection profiles, interpretable to a depth of about 730 m, were collected on the shallow-marine shelf of southeastern Florida in water as shallow as 1 m. Landward of the present-day shelf-margin slope, these data image middle Eocene to Pleistocene strata and Paleocene to Pleistocene strata on the Miami Terrace. This high-resolution data set provides an opportunity to evaluate geologic structures that cut across confining units of the Paleocene to Oligocene-age carbonate rocks that form the Floridan aquifer system.Seismic profiles image two structural systems, tectonic faults and karst collapse structures, which breach confining beds in the Floridan aquifer system. Both structural systems may serve as pathways for vertical groundwater flow across relatively low-permeability carbonate strata that separate zones of regionally extensive high-permeability rocks in the Floridan aquifer system. The tectonic faults occur as normal and reverse faults, and collapse-related faults have normal throw. The most common fault occurrence delineated on the reflection profiles is associated with karst collapse structures. These high-frequency seismic data are providing high quality structural analogs to unprecedented depths on the southeastern Florida Platform. The analogs can be used for assessment of confinement of other carbonate aquifers and the sealing potential of deeper carbonate rocks associated with reservoirs around the world.

  7. Estimation of Yield and Height-of-Burst for Near-Surface Explosions from Joint Inversion of Air-Blast and Seismic Data

    NASA Astrophysics Data System (ADS)

    Rodgers, A.; Xu, H.; Templeton, D. C.; Ramirez, A. L.; Chipman, V.; Ford, S. R.; Chambers, D. H.

    2011-12-01

    Near-surface explosions generate air-blast overpressure and seismic ground motions. It is well known that air-blast and seismic amplitudes depend on explosive yield and range. However for explosions near the ground surface the excitation of air-blast overpressure in the atmosphere and seismic motions depends strongly on the height-of-burst (HOB) for above ground or depth-of-burial (DOB, negative HOB) for buried explosions. We report an algorithm for estimating yield and HOB from near-surface explosions by joint inversion of air-blast overpressure and seismic ground motion amplitudes. The HUMBLE REDWOOD series of chemical explosions conducted at Kirtland AFB were explicitly designed to investigate the effect of HOB on air-blast and seismic motions. Analysis of these data indicates that scaled-range and HOB effects separate and provide calibration data for signal behavior with yield, range and HOB. Variation of air-blast measurements with scaled range for above ground explosions is reasonably well fit by reported models. Dependence with scaled HOB is determined with residuals from above ground air-blast models fit to a parameterized curve. Resampling of the data allows estimates of model errors for both scaled range and scaled HOB and is also used to propagate model errors in the inversion. Similar analysis is performed for the dependence of seismic amplitudes with scaled range and scaled HOB. The inversion of air-blast and seismic amplitudes for yield and HOB uses either a grid search or Markov Chain Monte Carlo (MCMC) approach. The algorithm runs very quickly in either case because the forward calculations are algebraic and very efficient for this two-dimensional model space. We show that inversion results obtained with only one data type (air-blast or seismic) are strongly non-unique and often have large bias. However, joint inversion of air-blast and seismic data breaks the trade-offs between yield and HOB and leads to more accurate estimates. We find that

  8. Two-dimensional Co-Seismic Surface Displacements Field of the Chi-Chi Earthquake Inferred from SAR Image Matching

    PubMed Central

    Hu, Jun; Li, Zhi-Wei; Ding, Xiao-Li; Zhu, Jian-Jun

    2008-01-01

    The Mw=7.6 Chi-Chi earthquake in Taiwan occurred in 1999 over the Chelungpu fault and caused a great surface rupture and severe damage. Differential Synthetic Aperture Radar Interferometry (DInSAR) has been applied previously to study the co-seismic ground displacements. There have however been significant limitations in the studies. First, only one-dimensional displacements along the Line-of-Sight (LOS) direction have been measured. The large horizontal displacements along the Chelungpu fault are largely missing from the measurements as the fault is nearly perpendicular to the LOS direction. Second, due to severe signal decorrelation on the hangling wall of the fault, the displacements in that area are un-measurable by differential InSAR method. We estimate the co-seismic displacements in both the azimuth and range directions with the method of SAR amplitude image matching. GPS observations at the 10 GPS stations are used to correct for the orbital ramp in the amplitude matching and to create the two-dimensional (2D) co-seismic surface displacements field using the descending ERS-2 SAR image pair. The results show that the co-seismic displacements range from about -2.0 m to 0.7 m in the azimuth direction (with the positive direction pointing to the flight direction), with the footwall side of the fault moving mainly southwards and the hanging wall side northwards. The displacements in the LOS direction range from about -0.5 m to 1.0 m, with the largest displacement occuring in the northeastern part of the hanging wall (the positive direction points to the satellite from ground). Comparing the results from amplitude matching with those from DInSAR, we can see that while only a very small fraction of the LOS displacement has been recovered by the DInSAR mehtod, the azimuth displacements cannot be well detected with the DInSAR measurements as they are almost perpendicular to the LOS. Therefore, the amplitude matching method is obviously more advantageous than the DIn

  9. Integration of borehole geophysical properties into surface multichannel seismic data sets: First results from the SCOPSCO ICDP project

    NASA Astrophysics Data System (ADS)

    Lindhorst, Katja; Krastel, Sebastian; Baumgarten, Henrike; Wonik, Thomas; Francke, Alexander; Wagner, Bernd

    2015-04-01

    Lake Ohrid (Macedonia/Albania), located on the Balkan Peninsula within the Dinaride-Hellenide-Albanide mountain belt is probably the oldest, continuously existing lake in Europe (2-5 Ma). Multidisciplinary studies at Lake Ohrid prove that it is an important archive to study the sedimentary and tectonic evolution of a graben system over a long time period. Within the frame of the International Continental Drilling Program (ICDP) a successful deep drilling campaign was carried out in spring 2013 with more than 2000 m of sediment cores at four sites. Downhole logging was realized at each site after coring, enabling us to integrate geophysical and sedimentological data into seismic cross sections in order to get a profound knowledge of climatic and environmental changes in the catchment area. The longest record (~569 m, site DEEP), recovered in the central part of lake Ohrid likely covers the entire lacustrine succession within Lake Ohrid Basin including several Interglacial and Glacial cycles. Sedimentological analyses are still ongoing; however, the upper 260 m of the DEEP reflecting the time period between Mid-Pleistocene Transition to present. An integration of borehole geophysical data into surface seismic lines shows that sediments, within the central part of Lake Ohrid, were deposited in a deep water environment over the last 600 ka. For the uppermost sediment cover, about 50 m of penetration, a very high resolution sediment echosounder data set allows us to identify major tephra layers and track them through the entire deep basin. Furthermore, a vertical seismic profile was carried out at site DEEP resulting in a conversion from two-way-travel-time into sediment depth. One major outcome is a corridor stack of the upgoing wave that clearly shows several reflectors linked to changes of sediment properties of cores and hence environmental and climate changes in the surrounding area of Lake Ohrid Basin. Several changes from Glacial to Interglacial, and vice versa

  10. Near-surface mapping using SH-wave and P-wave seismic land-streamer data acquisition in Illinois, U.S

    USGS Publications Warehouse

    Pugin, Andre J.M.; Larson, T.H.; Sargent, S.L.; McBride, J.H.; Bexfield, C.E.

    2004-01-01

    SH-wave and P-wave high-resolution seismic reflection combined with land-streamer technology provide 3D regional maps of geologic formations that can be associated with aquifers and aquitards. Examples for three study areas are considered to demonstrate this. In these areas, reflection profiling detected near-surface faulting and mapped a buried glacial valley and its aquifers in two settings. The resulting seismic data can be used directly to constrain hydrogeologic modeling of shallow aquifers.

  11. Passive seismic experiment - A summary of current status. [Apollo-initiated lunar surface station data

    NASA Technical Reports Server (NTRS)

    Latham, G. V.; Dorman, H. J.; Horvath, P.; Ibrahim, A. K.; Koyama, J.; Nakamura, Y.

    1978-01-01

    The data set obtained from the four-station Apollo seismic network including signals from approximately 11,800 events, is surveyed. Some refinement of the lunar model will result, but its gross features remain the same. Attention is given to the question of a small, molten lunar core, the answer to which remains dependent on analysis of signals from a far side impact. Seventy three sources of repeating, deep moonquakes have been identified, thirty nine of which have been accurately located. Concentrated at depths from 800 to 1000 km, the periodicities of these events have led to the hypothesis that they are generated by tidal stresses. Lunar seismic data has also indicated that the meteoroid population is ten times lower than originally determined from earth based observations. Lunar seismic activity is much lower and mountainous masses show no sign of sinking, in contrast to earth, as a result of the lunar crust being four times thicker. While much work remains to be done, significant correlation between terrestrial and lunar observations can be seen.

  12. Co-seismic surface effects from very high resolution panchromatic images: the case of the 2005 Kashmir (Pakistan) earthquake

    NASA Astrophysics Data System (ADS)

    Chini, M.; Cinti, F. R.; Stramondo, S.

    2011-03-01

    The use of Very High Resolution (VHR) satellite panchromatic image is nowadays an effective tool to detect and investigate surface effects of natural disasters. We specifically examined the capabilities of VHR images to analyse earthquake features and detect changes based on the combination of visual inspection and automatic classification tools. In particular, we have used Quickbird (0.6 m spatial resolution) images for detecting the three main co-seismic surface features: damages, ruptures and landslides. The present approach has been applied to the 8 October 2005, Mw7.6 Kashmir, Pakistan, earthquake. We have focused our study in and around the main urban areas hit by the above earthquake specifically at Muzaffarabad and Balakot towns. The automatic classification techniques provided the best results wherever dealing with the damage to man-made structures and landslides. On the other hand, the visual inspection method demonstrated in addressing the identification of rupture traces and associated features. The synoptic view (concerning landslide, more than 190 millions of pixels have been automatically classified), the spatiotemporal sampling and the fast automatic damage detection using satellite images provided a reliable contribution to the prompt response during natural disaster and for the evaluation of seismic hazard as well.

  13. Seismic imaging of crust and upper mantle structure in western North America via surface wave inversion and wavefield depropagation

    NASA Astrophysics Data System (ADS)

    Stachnik, Joshua C.

    Surface wave analysis of both earthquake and ambient noise seismic data from arrays of broadband seismic stations provides new high resolution images of shear wave velocity of the crust and upper mantle in western North America. In the Yellowstone Hotspot region, new constraints are shown on the high velocity midcrustal layer of the eastern Snake River Plain that represents approximately 10 km of magmatic thickening and subsequent forcing of lower crustal outflow. In the Coast Mountain Batholith area of western British Columbia, the lack of a significant region of high velocities in the lower crust indicates that the foundering of negatively buoyant eclogitic lower crust has been efficient. A high resolution shear velocity model of the Sierra Nevada batholith region finds crustal thickening beneath the batholith, sinking material beneath the central Sierras with adjacent upwelling asthenospheric mantle, and the new image suggests that the Isabella (San Joaquin Valley) anomaly has a quasi-planar NW-SE striking geometry perhaps more consistent with being a Monterey plate slab remnant than an eclogite dominated feature. In addition to the surface wave results, new constraints are found on the sharpness of the 410-km velocity discontinuity via the wave-field continuation approach applied to five regional earthquakes in western North America. The 410-km discontinuity gradient ranges from 7-25 km, indicating the presence of water atop the transition zone in the two regions with large 410 km discontinuity gradient widths.

  14. Seismic Studies

    SciTech Connect

    R. Quittmeyer

    2006-09-25

    This technical work plan (TWP) describes the efforts to develop and confirm seismic ground motion inputs used for preclosure design and probabilistic safety 'analyses and to assess the postclosure performance of a repository at Yucca Mountain, Nevada. As part of the effort to develop seismic inputs, the TWP covers testing and analyses that provide the technical basis for inputs to the seismic ground-motion site-response model. The TWP also addresses preparation of a seismic methodology report for submission to the U.S. Nuclear Regulatory Commission (NRC). The activities discussed in this TWP are planned for fiscal years (FY) 2006 through 2008. Some of the work enhances the technical basis for previously developed seismic inputs and reduces uncertainties and conservatism used in previous analyses and modeling. These activities support the defense of a license application. Other activities provide new results that will support development of the preclosure, safety case; these results directly support and will be included in the license application. Table 1 indicates which activities support the license application and which support licensing defense. The activities are listed in Section 1.2; the methods and approaches used to implement them are discussed in more detail in Section 2.2. Technical and performance objectives of this work scope are: (1) For annual ground motion exceedance probabilities appropriate for preclosure design analyses, provide site-specific seismic design acceleration response spectra for a range of damping values; strain-compatible soil properties; peak motions, strains, and curvatures as a function of depth; and time histories (acceleration, velocity, and displacement). Provide seismic design inputs for the waste emplacement level and for surface sites. Results should be consistent with the probabilistic seismic hazard analysis (PSHA) for Yucca Mountain and reflect, as appropriate, available knowledge on the limits to extreme ground motion at

  15. System and method for generating 3D images of non-linear properties of rock formation using surface seismic or surface to borehole seismic or both

    DOEpatents

    Vu, Cung Khac; Nihei, Kurt Toshimi; Johnson, Paul A.; Guyer, Robert A.; Ten Cate, James A.; Le Bas, Pierre-Yves; Larmat, Carene S.

    2016-06-07

    A system and method of characterizing properties of a medium from a non-linear interaction are include generating, by first and second acoustic sources disposed on a surface of the medium on a first line, first and second acoustic waves. The first and second acoustic sources are controllable such that trajectories of the first and second acoustic waves intersect in a mixing zone within the medium. The method further includes receiving, by a receiver positioned in a plane containing the first and second acoustic sources, a third acoustic wave generated by a non-linear mixing process from the first and second acoustic waves in the mixing zone; and creating a first two-dimensional image of non-linear properties or a first ratio of compressional velocity and shear velocity, or both, of the medium in a first plane generally perpendicular to the surface and containing the first line, based on the received third acoustic wave.

  16. Wavefield Inversion of Surface Waves for Delineating Seismic Structure in Saline Permafrost: A Case History from the Barrow Peninsula, AK

    NASA Astrophysics Data System (ADS)

    Dou, S.; Dreger, D. S.; Peterson, J.; Ulrich, C.; Dafflon, B.; Hubbard, S. S.; Ajo Franklin, J. B.

    2014-12-01

    Seismic investigations of permafrost are essential in cold-region applications including static corrections for seismic exploration and site characterization for infrastructure development. Surface-wave methods are advantageous because their applicability does not require regular velocity gradients. But distinct challenges also exist: The irregular velocity variations in permafrost, combined with the marked velocity contrasts between frozen and unfrozen ground, often yield complicated dispersion spectra in which higher-order and leaky modes are dominant. Owing to the difficulties in retrieving dispersion curves from such spectra, dispersion-curved-based inversion methods become inapplicable. Here we present a case study of using wavefield inversion of surface waves to infer the permafrost structure on the Barrow Peninsula of the Alaskan Arctic Coastal Plain. In May of 2014, we conducted an active multichannel surface-wave survey along a 4300-m (2.7-mi) NE-SW trending transect that extended from the coastal to the interior areas of the peninsula. We acquired surface-wave supergathers—each covering a distance of 147 meters—from four nearly equidistantly distributed subsections of the transect. The dispersion spectra show dominant higher-order and leaky modes, as well as inversely dispersive trends (i.e., phase velocities increase with increasing frequencies). Preliminary results reveal a "sandwich" velocity structure, in which a pronounced low-velocity layer (with S-wave velocity reductions up to ~45%-60%; tens of meters thick; overlain by 3-4 m of high-velocity strata) is embedded within high-velocity strata, and the low-velocity layer itself contains irregular velocity gradients. Considering the low ground temperatures of -10 °C to -8 °C, this low-velocity feature is likely to be an embedded saline layer that is only partially frozen due to freezing-point depression of dissolved salts. Because saline permafrost is particularly sensitive to thermal

  17. Time-lapse Monitoring of Geotechnical Properties of Heritage Earthworks by Means of Near-Surface Seismic Techniques

    NASA Astrophysics Data System (ADS)

    Bergamo, P.; Donohue, S.; Gunn, D.; Dashwood, B.

    2014-12-01

    Surface wave (SW) method and P-wave refraction tomography are widely spread methods for the characterization of the near-surface. We applied these techniques to a 1-year time-lapse monitoring of the geotechnical properties of a heritage earthwork at risk of failure, a stretch of the embankment of the Gloucestershire-Warwickshire railway in Laverton, UK. Like a significant part of UK railway network, this line was built in the early 20th century without modern construction standards. Poor maintenance and the increase in extreme weather events due to recent climate change have further compromised its stability. The aim of this monitoring campaign is to assess the capability of non-invasive and repeatable geophysical methods to measure temporal changes of mechanical parameters of earthworks. MASW (multichannel analysis of SW) and P-wave refraction data were repeatedly acquired along a 100 m line on the crest of the embankment, every other month from July 2013 to July 2014. Smaller scale seismic data were also recorded on the flanks of the embankment. Sensors measuring climate -temperature, precipitation, solar radiation - and geotechnical parameters - water content, suction - were installed at various locations and depths within the embankment. Moreover, penetrometric data were acquired, soil samples were analysed. SW data were analysed in terms of phase velocity and attenuation. Hodocrones, dispersion and attenuation curves show a limited but continuous seasonal change. SW dispersion curves and P-wave travel times were separately inverted for VS and VP models with a laterally constrained and a tomographic approach, respectively. The VS and VP sections describe the temporal variation of seismic properties of the embankment, consistent with the climate trend. Such results were jointly interpreted with data from field sensors and cone penetration testing. This calibration stage provides a geotechnical model that explains the temporal variations of seismic velocities

  18. Seismic Imaging of the San Jacinto Fault Zone Area From Seismogenic Depth to the Surface

    NASA Astrophysics Data System (ADS)

    Ben-Zion, Y.

    2015-12-01

    I review multi-scale multi-signal seismological results on structural properties within and around the San Jacinto Fault Zone (SJFZ). The results are based on data of the regional southern California and ANZA networks, additional near-fault seismometers and linear arrays with instrument spacing 25-50 m that cross the SJFZ at several locations, and a spatially-dense rectangular array with 1108 vertical-component sensors separated by 10-30 m centered on the fault. The studies utilize earthquake data to derive Vp and Vs velocity models with horizontal resolution of 1-2 km over the depth section 2-15 km, ambient noise with frequencies up to 1 Hz to image with similar horizontal resolution the depth section 0.5-7 km, and high-frequency seismic noise from the linear and rectangular arrays for high-resolution imaging of the top 0.5 km. Pronounced damage regions with low seismic velocities and anomalous Vp/Vs ratios are observed around the SJFZ, as well as the San Andreas and Elsinore faults. The damage zones follow generally a flower-shape with depth. The section of the SJFZ from Cajon pass to the San Jacinto basin has a faster SW side, while the section farther to the SE has an opposite velocity contrast with faster NE side. The damage zones and velocity contrasts produce at various locations fault zone trapped and head waves that are utilized to obtain high-resolution information on inner fault zone components (bimaterial interfaces, trapping structures). Analyses of high-frequency noise recorded by the fault zone arrays reveal complex shallow material with very low seismic velocities and strong lateral and vertical variations.

  19. Characterization of an earth-filled dam through the combined use of electrical resistivity tomography, P- and SH-wave seismic tomography and surface wave data

    NASA Astrophysics Data System (ADS)

    Cardarelli, E.; Cercato, M.; De Donno, G.

    2014-07-01

    The determination of the current state of buildings and infrastructures through non-invasive geophysical methods is a topic not yet covered by technical standards, since the application of high resolution geophysical investigations to structural targets is a relatively new technology. Earth-filled dam investigation is a typical engineering application of this type. We propose the integration of Electrical Resistivity Tomography and P- and SH-wave seismic measurements for imaging the geometry of the dam's body and the underlying soil foundations and to characterize the low strain elastic properties. Because S-wave velocity is closely tied to engineering properties such as shear strength, low-velocity zones in the S-wave velocity models are of particular interest. When acquiring seismic data on earth filled dams, it is not uncommon to encounter highly attenuative surface layers. If only lightweight seismic sources are available, the seismic data generally exhibit a narrow frequency bandwidth: the lack of high frequency components generally prevents from having good quality shallow reflections. If there is no possibility to increase the power as well as the frequency content of the seismic source, the integration of other seismic methods than reflection may be the only available way to achieve a reliable near surface seismic characterization. For these reasons, we combined P- and SH-wave tomography with Multichannel Analysis of Surface Waves to image the internal and the underlying soil foundations of an earth filled dam located in Central Italy. In the presence of moderate velocity contrasts, tomographic methods have proven successful in imaging near surface variations along both the horizontal and vertical directions. On the other hand, body wave propagation is severely affected by attenuation under the previously described conditions, so that the quality of picked traveltimes dramatically decreases with offset and, consequently, the tomographic investigation

  20. 18 CFR 3c.2 - Nonpublic information.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Nonpublic information. 3c.2 Section 3c.2 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY GENERAL RULES STANDARDS OF CONDUCT § 3c.2 Nonpublic information. (a) Section 1264(d)...

  1. 18 CFR 3c.2 - Nonpublic information.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 18 Conservation of Power and Water Resources 1 2014-04-01 2014-04-01 false Nonpublic information. 3c.2 Section 3c.2 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY GENERAL RULES STANDARDS OF CONDUCT § 3c.2 Nonpublic information. (a) Section 1264(d)...

  2. 18 CFR 3c.2 - Nonpublic information.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 18 Conservation of Power and Water Resources 1 2011-04-01 2011-04-01 false Nonpublic information. 3c.2 Section 3c.2 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY GENERAL RULES STANDARDS OF CONDUCT § 3c.2 Nonpublic information. (a) Section 1264(d)...

  3. 18 CFR 3c.2 - Nonpublic information.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 18 Conservation of Power and Water Resources 1 2012-04-01 2012-04-01 false Nonpublic information. 3c.2 Section 3c.2 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY GENERAL RULES STANDARDS OF CONDUCT § 3c.2 Nonpublic information. (a) Section 1264(d)...

  4. 18 CFR 3c.2 - Nonpublic information.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 18 Conservation of Power and Water Resources 1 2013-04-01 2013-04-01 false Nonpublic information. 3c.2 Section 3c.2 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY GENERAL RULES STANDARDS OF CONDUCT § 3c.2 Nonpublic information. (a) Section 1264(d)...

  5. Analysis of dispersion and attenuation of surface waves in poroelastic media in the exploration-seismic frequency band

    USGS Publications Warehouse

    Zhang, Y.; Xu, Y.; Xia, J.

    2011-01-01

    We analyse dispersion and attenuation of surface waves at free surfaces of possible vacuum/poroelastic media: permeable-'open pore', impermeable-'closed pore' and partially permeable boundaries, which have not been previously reported in detail by researchers, under different surface-permeable, viscous-damping, elastic and fluid-flowing conditions. Our discussion is focused on their characteristics in the exploration-seismic frequency band (a few through 200 Hz) for near-surface applications. We find two surface-wave modes exist, R1 waves for all conditions, and R2 waves for closed-pore and partially permeable conditions. For R1 waves, velocities disperse most under partially permeable conditions and least under the open-pore condition. High-coupling damping coefficients move the main dispersion frequency range to high frequencies. There is an f1 frequency dependence as a constant-Q model for attenuation at high frequencies. R1 waves for the open pore are most sensitive to elastic modulus variation, but least sensitive to tortuosities variation. R1 waves for partially permeable surface radiate as non-physical waves (Im(k) < 0) at low frequencies. For R2 waves, velocities are slightly lower than the bulk slow P2 waves. At low frequencies, both velocity and attenuation are diffusive of f1/2 frequency dependence, as P2 waves. It is found that for partially permeable surfaces, the attenuation displays -f1 frequency dependence as frequency increasing. High surface permeability, low-coupling damping coefficients, low Poisson's ratios, and low tortuosities increase the slope of the -f1 dependence. When the attenuation coefficients reach 0, R2 waves for partially permeable surface begin to radiate as non-physical waves. ?? 2011 The Authors Geophysical Journal International ?? 2011 RAS.

  6. Active normal faulting during the 1997 seismic sequence in Colfiorito, Umbria: Did slip propagate to the surface?

    NASA Astrophysics Data System (ADS)

    Mildon, Zoë K.; Roberts, Gerald P.; Faure Walker, Joanna P.; Wedmore, Luke N. J.; McCaffrey, Ken J. W.

    2016-10-01

    In order to determine whether slip during an earthquake on the 26th September 1997 propagated to the surface, structural data have been collected along a bedrock fault scarp in Umbria, Italy. These collected data are used to investigate the relationship between the throw associated with a debated surface rupture (observed as a pale unweathered stripe at the base of the bedrock fault scarp) and the strike, dip and slip-vector. Previous studies have suggested that the surface rupture was produced either by primary surface slip or secondary compaction of hangingwall sediments. Some authors favour the latter because sparse surface fault dip measurements do not match nodal plane dips at depth. It is demonstrated herein that the strike, dip and height of the surface rupture, represented by a pale unweathered stripe at the base of the bedrock scarp, shows a systematic relationship with respect to the geometry and kinematics of faulting in the bedrock. The strike and dip co-vary and the throw is greatest where the strike is oblique to the slip-vector azimuth where the highest dip values are recorded. This implies that the throw values vary to accommodate spatial variation in the strike and dip of the fault across fault plane corrugations, a feature that is predicted by theory describing conservation of strain along faults, but not by compaction. Furthermore, published earthquake locations and reported fault dips are consistent with the analysed surface scarps when natural variation for surface dips and uncertainty for nodal plane dips at depth are taken into account. This implies that the fresh stripe is indeed a primary coseismic surface rupture whose slip is connected to the seismogenic fault at depth. We discuss how this knowledge of the locations and geometry of the active faults can be used as an input for seismic hazard assessment.

  7. Time-lapse surface seismic data registration and inversion for CO2 sequestration at Cranfield

    NASA Astrophysics Data System (ADS)

    Zhang, R.; Song, X.; Fomel, S.; Sen, M. K.; Srinivasan, S.

    2012-12-01

    Time-lapse seismic survey for CO2 sequestration study at Cranfield can be problematic because of the misalignments between the time-lapse datasets. Unlike other studies of time-lapse monitoring that use time-shifts as the primary time-lapse effect, we assume that the misalignment of reflections in the Cranfield data is caused by aliasing. To correct for this misalignment so as to enable correct seismic amplitude difference calculation, we apply a local-correlation based warping method to register the post-injection and pre-injection datasets. The application of the registration demonstrates its effectiveness in robust estimation of the time-lapse difference resulting in laterally continuous amplitude. This helps further to apply a basis pursuit inversion on the time-lapse datasets for acoustic impedances. From the inverted time-lapse acoustic impedances and their difference, we identify a zone of strong impedance decrease occurring at the top of the injection interval, which agrees well with the well-log measurements.

  8. Using Three-Dimensional Passive Seismic Imaging to Capture Near-Surface Weathering and Its Influence on Overlying Vegetation

    NASA Astrophysics Data System (ADS)

    Taylor, N. J.; Dueker, K. G.; Riebe, C. S.; Chen, P.; Flinchum, B. A.; Holbrook, W. S.

    2015-12-01

    In mountain landscapes, vegetation is tightly coupled to elevation through orographic effects on temperature and precipitation. However, at any given elevation, vegetation can vary markedly due to non-climatic factors such as lithology. For example, tree-canopy cover correlates strongly with bedrock composition in the Sierra Nevada, California, via mechanisms that remain poorly understood. We are exploring the hypothesis that vegetation varies across bedrock types in the Sierra Nevada due to differences in near-surface fracture density that influence the availability of water for plants. Our approach uses data collected from autonomous seismic nodes that record seismic energy generated by ambient sources such as wind, rivers, and road traffic. By deploying the nodes across the landscape in arrays spanning 200 m on a side, we can obtain a three-dimensional image of spatial variations in near-surface weathering. Data presented here will be derived from arrays deployed for 3 days each spanning an area of 0.04 km2 at each of three sites underlain by Sierra Nevada granites and granodiorites. To isolate the effects of lithology on vegetation, we chose sites that span a range of forest cover and mafic-mineral content but have similar microclimate (i.e., with similar aspect and elevation). Our data will provide a three-dimensional model of P- and S-wave velocity structure, which we can invert using a Hertz-Mindlin porosity model to constrain the thickness and degree of fracturing and thus the subsurface water-holding potential for plants. We will explore the hypothesis that the densest vegetation occurs within bedrock with the densest fracturing, due to enhanced availability of water in the near surface. We will present a comparison of our results from the Sierra Nevada and results from similar experiments at the Snowy Range and Blair Wallis field sites of the Wyoming Center for Environmental Hydrology and Geophysics.

  9. Correlations between seismic wave velocities and physical properties of near-surface geologic materials in the southern San Francisco Bay region, California

    USGS Publications Warehouse

    Fumal, Thomas E.

    1978-01-01

    To identify geologic units with distinctly different seismic responses for the purposes of seismic zonation, compressional and shear wave velocities have been measured in boreholes at 59 sites in the San Francisco Bay region in a wide range of near-surface (0-30m) geologic materials. Several physical parameters, which can be readily determined in the field, were found to correlate with the shear wave velocities and were used to define seismically distinct groups. For the unconsolidated to semiconsolidated sediments, texture, standard penetration resistance and depth were used to define eight seismically distinct groups. For the bedrock materials, fracture spacing and hardness were used to differentiate ten distinct categories. The correlation obtained between shear wave velocity and the physical parameters were used to regroup the map units defined for the San Francisco Bay region into seismically distinct units. The map units for the younger unconsolidated sediments can be really differentiated seismically. In contrast, the older semiconsolidated sedimentary deposits and bedrock units, which have experienced significant variations in post-depositial changes, show wider and overlapping velocity ranges. The map units for the sedimentary deposits have been regrouped into eight seismically distinct geotechnical units. The bedrock map units have been broadly regrouped into five distinct categories. Compressional wave velocities were not found to be well correlated with the physical parameters dependent on the soil or rock structure. For materials above the water table, the wide velocity variations found for each geotechnical group can be attributed to differences in degree of saturation. The strong correlations observed between shear wave velocity and other readily determine physical properties suggest that geologic maps which incorporate these parameters are most useful for seismic zonation.

  10. Yields of Soviet underground nuclear explosions from seismic surface waves: Compliance with the Threshold Test Ban Treaty.

    PubMed

    Sykes, L R; Cifuentes, I L

    1984-03-01

    Magnitudes of the larger Soviet underground nuclear weapons tests from the start of the Threshold Test Ban Treaty in 1976 through 1982 are determined for short- and long-period seismic waves. Yields are calculated from the surface wave magnitude for those explosions at the eastern Kazakh test site that triggered a small-to-negligible component of tectonic stress and are used to calibrate body wave magnitude-yield relationship that can be used to determine the sizes of other explosions at that test site. The results confirm that a large bias, related to differential attenuation of P waves, exists between Nevada and Central Asia. The yields of the seven largest Soviet explosions are nearly identical and are close to 150 kilotons, the limit set by the Threshold Treaty.

  11. Seismic Images of Near-Surface Faulting Along the Northern Projection of the Silver Creek Fault, Eastern and Southern San Francisco Bay, California

    NASA Astrophysics Data System (ADS)

    Catchings, R. D.; Rymer, M. J.; Goldman, M. R.; Gandhok, G.; Sickler, R. R.

    2008-12-01

    We acquired high-resolution shallow-depth and lower-resolution crustal-scale images across the northern projection of the Silver Creek in the Eastern San Francisco Bay, California. On a regional seismic profile from the Pacific Ocean to the Livermore Valley, the Silver Creek fault approximately marks the boundary between high velocities beneath the San Francisco Bay and lower velocities to the east, suggesting that the Silver Creek fault represents a major structural boundary between the San Andreas and Hayward faults. Locally, we acquired a series of high-resolution seismic profiles across the alluvial-covered northern projection of the Silver Creek fault, as inferred from vertical offsets in the groundwater table and from InSAR images. In San Jose, we found evidence for near-surface faulting across the Silver Creek fault as reported in a companion abstract by Goldman et al. (this volume). Along the Fremont/Union City Border at Alameda Creek, we acquired an approximately 2-km-long high-resolution seismic reflection/refraction profile that shows vertical offsets of near-surface strata and the underlying bedrock, and farther north in San Lorenzo, we acquired an approximately 8-km-long high-resolution seismic reflection/refraction profile that also shows vertical offsets of near-surface strata and the underlying bedrock. Both profiles show the apparent faulting along the northward projection of the Silver Creek fault. Although the vast majority of seismic events recorded in the area can be attributed to the slip on the Hayward fault, the northern California seismic catalog shows that some events occur beneath the near-surface trace of the Silver Creek fault. Collectively, the available data indicate that the Silver Creek fault may be more than 80 km long and may be currently or recently active. Because of its proximity to high-population centers, more careful examination of this fault is warranted.

  12. Estimation of seismic wave velocity at seafloor surface and sound source localization based on transmitted wave observation with an ocean bottom seismometer offshore of Kamaishi, Japan

    NASA Astrophysics Data System (ADS)

    Iwase, Ryoichi

    2016-07-01

    An in situ method of estimating the seismic wave velocity at the seafloor surface by observing the particle motion of a wave transmitted into the sediment is presented; this method uses a sound source whose location is known. Conversely, a sound source localization method using the obtained seismic velocities and involving particle motion observation is also presented. Although this method is applicable only when the sound source exists within the critical incidence angle range, it is expected to contribute to the tracing of vocalizing baleen whales, which are unknown around Japanese waters.

  13. First-arrival traveltime tomography of regional-scale seismic-reflection data to image near-surface Quaternary and Tertiary sediments in Northern Switzerland

    NASA Astrophysics Data System (ADS)

    Hofstetter, Florian; Schmelzbach, Cedric; Horstmeyer, Heinrich; Hertrich, Marian; Buechi, Marius W.

    2014-05-01

    Regional-scale seismic-reflection data have usually a limited potential for imaging the shallow (<100 m) subsurface. However, resolving near-surface units is of significant interest for various purposes such as weathering-layer corrections in seismic-reflection processing but also to study Quaternary sediments and their geologic history. In this study, we inverted the first-arrival traveltimes of a recently acquired regional-scale seismic-exploration data set from Northern Switzerland. The overall motivation was to complement the seismic-reflection investigations and to image the shallow subsurface with seismic-refraction tomography. Whereas the surface distribution of the Quaternary and Tertiary sediments is mapped in detail in the investigation area, the highly variable thickness of the Quaternary sediments (up to 150 m) is only constrained at a few borehole locations. We focused on a ~9 km long stretch of a 2-D seismic-reflection profile that was acquired with short source and receiver intervals varying between 6 and 12 m. A total of 450'000 traveltimes was picked from mostly Vibroseis and few dynamite data with varying quality due to partly strong sweep-correlation noise and the data were inverted using a regularized inversion scheme. The robustness of the velocity models was assessed based on traveltime residuals, start model and free-parameter variation, and ray coverage. The final tomograms image the subsurface down to a depth of ~700 m. Shallow low (< 2000 m/s) seismic velocity zones correlate well with mapped Quaternary sediment units in the valleys. Geological and seismic-velocity information from three boreholes allows to correlate a distinct velocity increase at ~50 to 100 m depth with the Quaternary-Tertiary sediment interface. Velocity isolines allow tracing the Quaternary-sediment thickness away from the boreholes and significantly aid in updating a pre-existing Quaternary-sediment thickness model. An extensive about 100 m thick body with very low

  14. The high energy source 3C 273

    NASA Technical Reports Server (NTRS)

    Vonmontigny, Corinna

    1990-01-01

    The properties of 3C 273 are reviewed and an attempt is made to find an answer to the question why 3C 273 is the only extragalactic source so far, which was detected at energies greater than or equal to 50 MeV.

  15. Near-surface structure of the Central Scandinavian Caledonides in northern Trøndelag, Norway, from correlation of seismic and MT profiles using gravity and magnetic data

    NASA Astrophysics Data System (ADS)

    Ebbing, J.; Goerigk, L.; Nasuti, A.; Roberts, D.; Korja, T. J.; Smirnov, M.

    2014-12-01

    The deep geology of northern Trøndelag is somewhat speculative as the Central Scandinavian Caledonides are intersected by the Møre-Trøndelag Fault Complex (MTFC) and only a few depth-penetrating geophysical profiles exist. Here, we correlate the mapped geological units and faults between a seismic-reflection profile and a MT profile. The seismic-reflection data were acquired in 5 segments over the period 1986-1990. The westernmost section of the seismic profile is dominated by a complex pattern of reflections and diffractions. This type of pattern is typical of polydeformed terranes with a mixture of contrasting felsic and mafic lithologies. The two steeply-dipping strands of the MTFC (Hitra-Snåsa and Verran faults) that transect the profile do not show any distinctive signature in the seismic data. The MT data were acquired in 2007 from the Swedish border to the Norwegian coast. The conductivity profile shows some distinct vertical changes as well as changes from the near-surface to shallow depths. The strands of the MTFC show especially a distinctive change in conductivity. The two profiles are almost parallel but separated by 100 km. To correlate the structures seen on both profiles, we have applied lineament analysis and 3D modelling of the gravity and magnetic field. The tilt derivative of the magnetic and isostatic gravity anomaly clearly allows us to identify and link the main geological boundaries between the profiles and to trace the strands of the MTFC from one profile to the other. This trend analysis indicates that at least the Verran Fault visibly modifies the pattern of seismic reflections. However, the main change in crustal lithology occurs farther to the west, almost at the coast where the Tarva Fault intersects the MT profile. This integrated analysis shows the benefit of combining gravity and magnetic interpretations with MT and seismic data to enable us to understand the near-surface geology and structure in more detail.

  16. The Detection of Vertical Cracks in Asphalt Using Seismic Surface Wave Methods

    NASA Astrophysics Data System (ADS)

    Iodice, M.; Muggleton, J.; Rustighi, E.

    2016-09-01

    Assessment of the location and of the extension of cracking in road surfaces is important for determining the potential level of deterioration in the road overall and the infrastructure buried beneath it. Damage in a pavement structure is usually initiated in the tarmac layers, making the Rayleigh wave ideally suited for the detection of shallow surface defects. This paper presents an investigation of two surface wave methods to detect and locate top-down cracks in asphalt layers. The aim of the study is to compare the results from the well- established Multichannel Analysis of Surface Waves (MASW) and the more recent Multiple Impact of Surface Waves (MISW) in the presence of a discontinuity and to suggest the best surface wave technique for evaluating the presence and the extension of vertical cracks in roads. The study is conducted through numerical simulations alongside experimental investigations and it considers the cases for which the cracking is internal and external to the deployment of sensors. MISW is found to enhance the visibility of the reflected waves in the frequency wavenumber (f-k) spectrum, helping with the detection of the discontinuity. In some cases, by looking at the f-k spectrum obtained with MISW it is possible to extract information regarding the location and the depth of the cracking.

  17. Application of seismic surface-waves in concrete bridge-deck evaluation

    NASA Astrophysics Data System (ADS)

    Fetrat, Farhad

    Accurate and timely condition assessment of bridge decks is essential for economic management of aging highway bridges. The ability to evaluate concrete modulus profile in a bridge deck can help the detection of early signs of deterioration and optimize the bridge maintenance procedures. This study presents a new method for modulus profiling of concrete bridge decks. The stiffness matrix method is used to simulate wave propagation in a layered media. The results are compared to numerical finite element models. Dispersion analysis is done using the multi-channel analysis of surface waves (MASW) and phase-shift methods. The characteristics of dispersion surface are analyzed and the effects of model parameters on dispersion surface are examined through a series of parametric studies. An inversion technique is proposed for a fast inversion of surface-wave data collected on bridge decks. This technique utilizes a database of pre-calculated dispersion surfaces and takes advantage of the observed patterns in the parametric study as a priori information for the inversion process.

  18. Analysis and models of pre-injection surface seismic array noise recorded at the Aquistore carbon storage site

    NASA Astrophysics Data System (ADS)

    Birnie, Claire; Chambers, Kit; Angus, Doug; Stork, Anna L.

    2016-08-01

    Noise is a persistent feature in seismic data and so poses challenges in extracting increased accuracy in seismic images and physical interpretation of the subsurface. In this paper, we analyse passive seismic data from the Aquistore carbon capture and storage pilot project permanent seismic array to characterise, classify and model seismic noise. We perform noise analysis for a three-month subset of passive seismic data from the array and provide conclusive evidence that the noise field is not white, stationary, or Gaussian; characteristics commonly yet erroneously assumed in most conventional noise models. We introduce a novel noise modelling method that provides a significantly more accurate characterisation of real seismic noise compared to conventional methods, which is quantified using the Mann-Whitney-White statistical test. This method is based on a statistical covariance modelling approach created through the modelling of individual noise signals. The identification of individual noise signals, broadly classified as stationary, pseudo-stationary and non-stationary, provides a basis on which to build an appropriate spatial and temporal noise field model. Furthermore, we have developed a workflow to incorporate realistic noise models within synthetic seismic data sets providing an opportunity to test and analyse detection and imaging algorithms under realistic noise conditions.

  19. Blind test of methods for obtaining 2-D near-surface seismic velocity models from first-arrival traveltimes

    USGS Publications Warehouse

    Zelt, Colin A.; Haines, Seth; Powers, Michael H.; Sheehan, Jacob; Rohdewald, Siegfried; Link, Curtis; Hayashi, Koichi; Zhao, Don; Zhou, Hua-wei; Burton, Bethany L.; Petersen, Uni K.; Bonal, Nedra D.; Doll, William E.

    2013-01-01

    Seismic refraction methods are used in environmental and engineering studies to image the shallow subsurface. We present a blind test of inversion and tomographic refraction analysis methods using a synthetic first-arrival-time dataset that was made available to the community in 2010. The data are realistic in terms of the near-surface velocity model, shot-receiver geometry and the data's frequency and added noise. Fourteen estimated models were determined by ten participants using eight different inversion algorithms, with the true model unknown to the participants until it was revealed at a session at the 2011 SAGEEP meeting. The estimated models are generally consistent in terms of their large-scale features, demonstrating the robustness of refraction data inversion in general, and the eight inversion algorithms in particular. When compared to the true model, all of the estimated models contain a smooth expression of its two main features: a large offset in the bedrock and the top of a steeply dipping low-velocity fault zone. The estimated models do not contain a subtle low-velocity zone and other fine-scale features, in accord with conventional wisdom. Together, the results support confidence in the reliability and robustness of modern refraction inversion and tomographic methods.

  20. Seismic system and method

    SciTech Connect

    Rietsch, E.F.

    1988-10-11

    This patent describes aeismic apparatus for providing an enhanced seismic signal comprising: a plurality of seismic detector means for detecting vibrations of the earth surface and providing a corresponding plurality of seismic signals representative of the detected vibrations, multiplexing means for multiplexing the seismic signals from the seismic detector means to provide a multiplexed signal, memory means receiving the multiplexed signals for separating and storing portions of the multiplexed signal according to the detector means of origin so that each stored portion is in effect a sample of a seismic signal from a detector means, means for deriving from the stored samples a statistical reference for the seismic signals from the plurality of detector means, means for discarding outlying samples from the stored samples in accordance with the statistical reference, means for combining the remaining samples in a predetermined manner to provide an enhanced seismic signal, and means connected to the discarding means for determining whether or not a statistical significant deviation exists between the rejection rates of the seismic detector means.

  1. Seismic Tomography of the Continental United States from a Joint Inversion of Surface Waves and Body Waves

    NASA Astrophysics Data System (ADS)

    Golos, E. M.; Yao, H.; Zhang, H.; Fang, H.; Burdick, S.; Schaeffer, A. J.; Vernon, F.; Lebedev, S.; van der Hilst, R. D.

    2015-12-01

    We present a model of seismic velocity anomalies for the entire continental United States—coast to coast, surface to lower mantle—using a joint body wave-surface wave inversion. This technique (Zhang et al., 2014), performed on a global adaptively-spaced grid, exploits the good vertical resolution at shallow depths of surface wave data, and the sampling of the deep mantle by teleseismic body (P and S) waves. The resultant model has better resolution at all depths than either method alone, enabling evaluation of interactions between lithospheric and mantle processes. We utilize the depth-dependence of surface wave sensitivity kernels to express surface wave phase velocity data directly in terms of spatial velocity structure (Fang et al., 2015). The data used are Rayleigh wave phase velocities from earthquakes and ambient noise (Schaeffer and Lebedev, 2013; Ekström, 2014) and S phase travel times from USArray, measured at the Array National Facility (ANF). We include a suite of synthetic tests to verify the performance of the inversion and compare it to results from traditional tomographic methods. We also use P arrivals and the influence of Vp on Rayleigh wave propagation speed to generate a preliminary model of Vp variations, independent from but consistent with the Vs model. Our model corroborates the well-established pattern of slow anomalies in the western US, especially in the Basin and Range and Rio Grande Rift regions. New details emerge in the eastern US, thanks to increasing data from the region. A distinction is observed between widespread fast lithospheric anomalies, associated with stable cratonic material, and deeper fast features, associated with the remnants of the Farallon Plate. It has been proposed that these fragments, near the mantle transition zones, still affect mantle dynamics (Forte et al., 2007), so better resolution of these anomalies is an important advancement. In addition, slower velocities are observed beneath the Appalachians and

  2. Determining Engineering Properties of the Shallow Lunar Subsurface using Seismic Surface Wave Techniques

    NASA Astrophysics Data System (ADS)

    Yeluru, P. M.; Baker, G. S.

    2008-12-01

    The geology of Earth's moon has previously been examined via telescopic observations, orbiting spacecraft readings, lunar sample analysis, and also from some geophysical data. Previous researchers have examined layering of the moon and models exist explaining the velocity variations in the mantle and core. However, no studies (or datasets) currently exist regarding the engineering properties of the shallow (<30 m) lunar subsurface. Engineering properties--like shear modulus and Poisson's ratio--are key parameters for civil engineering works, as they characterize the mechanical behavior of geotechnical materials under various types of loading. Therefore, understanding the physical and engineering properties within the upper 30 m of the lunar subsurface will be critical for lunar exploration if deployment of large structures, large-scale excavation, and/or landing of large spacecraft on the surface is desired. Advances in near-surface geophysical techniques, such as Multi-channel Analysis of Surface Wave (MASW), has greatly increased our ability to map subsurface variations in physical properties. The MASW method involves deployment of multiple seismometers to acquire 1-D or 2-D shear wave velocity profiles that can be directly related to various engineering properties. The advantage of this technique over drilling boreholes or any other geophysical technique is that it is less intensive, non-invasive, more cost- effective, and more robust because strong surface-wave records are almost guaranteed. In addition, data processing and analysis is fairly straightforward, and the MASW method allows for analysis of a large area of interest as compared to drilling boreholes. A new scheme using randomly distributed geophones (likely deployed from a mortar-type device) instead of a conventional linear array will be presented. A random array is necessary for lunar exploration because of the logistical constraints involved in deploying a linear or circular array robotically or by

  3. Seismic Anisotropy from the Core-Mantle Boundary to the Surface

    NASA Astrophysics Data System (ADS)

    Lynner, Colton Lee

    Subduction systems are vitally important to plate tectonics and mantle convection, but questions remain about many aspects of subduction dynamics, particularly the nature of sub-slab mantle flow. Observations of seismic anisotropy can shed light on the pattern of mantle flow in subduction systems. Understanding the sub-slab mantle is the focus of my first three chapters as well as my last chapter. In Chapters 1 and 2, I examine the sub-slab anisotropy beneath the Caribbean, Scotia, Central America, Alaska-Aleutians, Sumatra, Ryukyu, and IzuBonin-Japan-Kurile subduction systems. I find that measured fast splitting directions in these regions generally fall into two broad categories, aligning either with the strike of the trench or with the motion of the subducting slab relative to the overriding plate. In theses systems, there is a correlation between fast direction and age of the subducting lithosphere; older lithosphere (> 95 Ma) is associated with trench parallel splitting while younger lithosphere (< 95 Ma) is associated with plate-motion parallel fast splitting directions. In Chapter 3, I compile measurements from recent studies of source-side splitting studies to test the predictions of a number of recently proposed conceptual models for the dynamics of the sub-slab mantle. I find that a model in which fast splitting directions are determined by slab age matches the observations better than either the 3D-return flow or radial anisotropic models. Based on this observation, I propose that the sub-slab mantle is characterized by two distinct anisotropic and mantle flow regimes. Beneath younger lithosphere (< 95 Ma), I propose the sub-slab mantle is characterized by 2-D entrained flow resulting in an entrained mantle layer. Beneath older lithosphere (> 95 Ma), the entrained layer is thin and effectively serves as decoupling layer; the dynamics of the sub-slab region beneath old lithosphere is therefore dominated by three-dimensional return flow. In Chapters 4 and

  4. Surface seismic measurements of the Project GASBUGGY explosion at intermediate distance ranges

    USGS Publications Warehouse

    Warren, David H.; Jackson, W.H.

    1968-01-01

    Project GASBUGGY was an experiment performed by the Atomic Energy Commission, the El Paso Natural Gas Company, and the Bureau of Mines, U.S. Department of the Interior, to determine the effectiveness of a method for increasing the recovery of natural gas by large-scale fracturing of a gas-bearing formation with an underground nuclear explosion. The Project GASBUGGY nuclear explosive of 26 kilotons design yield was detonated on Sunday, December 10, 1967, at 1230:00 Mountain Standard Time. Lawrence Radiation Laboratory reported that the explosive was emplaced at 4240 ft below the ground surface, 1770 ft from the west line and 1218 ft from the south line in Section 36 of Township 29 North, Range 4 West, in Rio Arriba County, New Mexico, about 55 air miles east of the city of Farmington, New Mexico. The geodetic coordinates are: Latitude 36?40'40.4" North, and Longitude 107?12'30.3" West. The elevation of surface ground zero was 7204 ft above Mean Sea Level. The detonation occurred in the Lewis shale about 40 ft below its contact with the gas-bearing Pictured Cliffs sandstone. Early indications are that the explosive performed satisfactorily. This document is submitted as a preliminary data report. Additional analyses of the data will be prepared at a later time.

  5. Seismic Velocity Structure and Depth-Dependence of Anisotropy in the Red Sea and Arabian Shield from Surface Wave Analysis

    SciTech Connect

    Hansen, S; Gaherty, J; Schwartz, S; Rodgers, A; Al-Amri, A

    2007-07-25

    We investigate the lithospheric and upper mantle structure as well as the depth-dependence of anisotropy along the Red Sea and beneath the Arabian Peninsula using receiver function constraints and phase velocities of surface waves traversing two transects of stations from the Saudi Arabian National Digital Seismic Network. Frequency-dependent phase delays of fundamental-mode Love and Rayleigh waves, measured using a cross-correlation procedure, require very slow shear velocities and the presence of anisotropy throughout the upper mantle. Linearized inversion of these data produce path-averaged 1D radially anisotropic models with about 4% anisotropy in the lithosphere, increasing to about 4.8% anisotropy across the lithosphere-asthenosphere boundary (LAB). Models with reasonable crustal velocities in which the mantle lithosphere is isotropic cannot satisfy the data. The lithospheric lid, which ranges in thickness from about 70 km near the Red Sea coast to about 90 km beneath the Arabian Shield, is underlain by a pronounced low-velocity zone with shear velocities as low as 4.1 km/s. Forward models, which are constructed from previously determined shear-wave splitting estimates, can reconcile surface and body wave observations of anisotropy. The low shear velocity values are similar to many other continental rift and oceanic ridge environments. These low velocities combined with the sharp velocity contrast across the LAB may indicate the presence of partial melt beneath Arabia. The anisotropic signature primarily reflects a combination of plate- and density-driven flow associated with active rifting processes in the Red Sea.

  6. NATO-3C/Delta launch

    NASA Technical Reports Server (NTRS)

    1978-01-01

    NATO-3C, the third in a series of NATO defense-related communication satellites, is scheduled to be launched on a delta vehicle from the Eastern Test Range no earlier than November 15, 1978. NATO-3A and -3B were successfully launched by Delta vehicles in April 1976 and January 1977, respectively. The NATO-3C spacecraft will be capable of transmitting voice, data, facsimile, and telex messages among military ground stations. The launch vehicle for the NATO-3C mission will be the Delta 2914 configuration. The launch vehicle is to place the spacecraft in a synchronous transfer orbit. The spacecraft Apogee Kick motor is to be fired at fifth transfer orbit apogee to circularize its orbit at geosynchronous altitude of 35,900 km(22,260 miles) above the equator over the Atlantic Ocean somewhere between 45 and 50 degrees W longitude.

  7. High-precision geologic mapping to evaluate the potential for seismic surface rupture at TA-55, Los Alamos National Laboratory

    SciTech Connect

    Gardner, J.N.; Lavine, A.; Vaniman, D.; WoldeGabriel, G.

    1998-06-01

    In this report the authors document results of high-precision geologic mapping in the vicinity of TA-55 that has been done to identify parts of the southern portion of the Rendija Canyon Fault, or any other faults, with the potential for seismic surface rupture. To assess the potential for surface rupture at TA-55, an area of approximately 3 square miles that includes the Los Alamos County Landfill and Twomile, Mortandad, and Sandia Canyons has been mapped in detail. Map units are mostly cooling or flow units within the Tshirege Member (1.2 Ma) of the Bandelier Tuff. Stratigraphic markers that are useful for determining offsets in the map area include a distinct welding break at or near the cooling Unit 2-Unit 3 contact, and the Unit 3-Unit 4 contact. At the County Landfill the contact between the Tshirege Member of the Bandelier Tuff and overlying Quaternary alluvium has also been mapped. The mapping indicates that there is no faulting in the near-surface directly below TA-55, and that the closest fault is about 1500 feet west of the Plutonium Facility. Faulting is more abundant on the western edge of the map area, west of TA-48 in uppermost Mortandad Canyon, upper Sandia Canyon, and at the County Landfill. Measured vertical offsets on the faults range from 1 to 8 feet on mapped Bandelier Tuff contacts. Faulting exposed at the Los Alamos County Landfill has deformed a zone over 1000 feet wide, and has a net vertical down-to-the-west displacement of at least 15 feet in the Bandelier Tuff. Individual faults at the landfill have from less than 1 foot to greater than 15 feet of vertical offset on the Bandelier Tuff. Most faults in the landfill trend N-S, N20W, or N45E. Results of the mapping indicate that the Rendija Canyon Fault does not continue directly south to TA-55. At present, the authors have insufficient data to connect faulting they have mapped to areas of known faulting to the north or south of the study area.

  8. Effects of charge design features on parameters of acoustic and seismic waves and cratering, for SMR chemical surface explosions

    NASA Astrophysics Data System (ADS)

    Gitterman, Y.

    2012-04-01

    A series of experimental on-surface shots was designed and conducted by the Geophysical Institute of Israel at Sayarim Military Range (SMR) in Negev desert, including two large calibration explosions: about 82 tons of strong IMI explosives in August 2009, and about 100 tons of ANFO explosives in January 2011. It was a collaborative effort between Israel, CTBTO, USA and several European countries, with the main goal to provide fully controlled ground truth (GT0) infrasound sources in different weather/wind conditions, for calibration of IMS infrasound stations in Europe, Middle East and Asia. Strong boosters and the upward charge detonation scheme were applied to provide a reduced energy release to the ground and an enlarged energy radiation to the atmosphere, producing enhanced infrasound signals, for better observation at far-regional stations. The following observations and results indicate on the required explosives energy partition for this charge design: 1) crater size and local seismic (duration) magnitudes were found smaller than expected for these large surface explosions; 2) small test shots of the same charge (1 ton) conducted at SMR with different detonation directions showed clearly lower seismic amplitudes/energy and smaller crater size for the upward detonation; 3) many infrasound stations at local and regional distances showed higher than expected peak amplitudes, even after application of a wind-correction procedure. For the large-scale explosions, high-pressure gauges were deployed at 100-600 m to record air-blast properties, evaluate the efficiency of the charge design and energy generation, and provide a reliable estimation of the charge yield. Empirical relations for air-blast parameters - peak pressure, impulse and the Secondary Shock (SS) time delay - depending on distance, were developed and analyzed. The parameters, scaled by the cubic root of estimated TNT equivalent charges, were found consistent for all analyzed explosions, except of SS

  9. Graphene/3C-SiC Hybrid Nanolaminate.

    PubMed

    Zhuang, Hao; Yang, Bing; Heuser, Steffen; Huang, Nan; Fu, Haiyuan; Jiang, Xin

    2015-12-30

    In this work, we demonstrate a one-step approach to create graphene/3C-SiC nanolaminate structure using microwave plasma chemical vapor deposition technique. Layer-by-layer arrangement of thin 3C-SiC layers and graphene sheets is obtained with the thicknesses of the individual 3C-SiC layers and graphene sheets being 5-10 nm and 2-5 nm, respectively. An intimate contact between 3C-SiC and the graphene sheets is achieved and the nanolaminate film shows a high room temperature conductivity of 96.1 S/cm. A dedicated structural analysis of the nanolaminates by means of high-resolution transmission electron microscopy (HRTEM) reveals that the growth of the nanolaminates follows an iterative process: preferential graphene nucleation around the planar defects at the central region of the SiC layer, leading to the "splitting" of the SiC layer; and the thickening of the SiC layer after being "split". A growth mechanism based on both kinetics and thermodynamics is proposed. Following the proposed mechanism, it is possible to control the layer thickness of the graphene/3C-SiC hybrid nanolaminate by manipulating the carbon concentration in the gas phase, which is further experimentally verified. The high electrical conductivity, large surface area porous structure, feasible integration on different substrates (metal, Mo; semiconductor, Si and 2H-SiC; insulator, diamond) of the graphene/3C-SiC hybrid nanolaminate as well as other unprecedented advantages of the nanolaminate structure make it very promising for applications in mechanical, energy, and sensor-related areas. PMID:26650041

  10. Measurement of near-surface seismic compressional wave velocities using refraction tomography at a proposed construction site on the Presidio of Monterey, California

    USGS Publications Warehouse

    Powers, Michael H.; Burton, Bethany L.

    2012-01-01

    The U.S. Army Corps of Engineers is determining the feasibility of constructing a new barracks building on the U.S. Army Presidio of Monterey in Monterey, California. Due to the presence of an endangered orchid in the proposed area, invasive techniques such as exploratory drill holes are prohibited. To aid in determining the feasibility, budget, and design of this building, a compressional-wave seismic refraction survey was proposed by the U.S. Geological Survey as an alternative means of investigating the depth to competent bedrock. Two sub-parallel profiles were acquired along an existing foot path and a fence line to minimize impacts on the endangered flora. The compressional-wave seismic refraction tomography data for both profiles indicate that no competent rock classified as non-rippable or marginally rippable exists within the top 30 feet beneath the ground surface.

  11. Search for hydraulic connectivity between surface reservoirs and surrounding aquifers in the reservoir-triggered seismic environment (Koyna region, India) using hydrochemical and isotopic signatures

    NASA Astrophysics Data System (ADS)

    Reddy, D. V.; Nagabhushanam, P.

    2016-01-01

    Triggered seismicity is an accepted hypothesis in the present days. However, detailed hydrogeological investigations are lacking in the well-known reservoir-triggered seismic (RTS) zones. Here, we made an attempt to understand the direct linkage between the well-known Koyna-Warna reservoirs believed to be under the RTS zone (situated in the Deccan volcanic province (DVP), India) and the surrounding groundwater system up to 250 m deep from the ground surface. Seismic activity in the region started soon after the impoundment of water in the Koyna reservoir and being continued over the last four and a half decades. Though researchers have carried out numerous studies on the Koyna seismicity, no hydrogeological investigations were attempted. Hence, hydrogeological, hydrochemical, and isotopic investigations were carried out for 7 years on groundwaters from 15 deep bore wells (up to 250 m) and two surface reservoir waters to elucidate the direct hydraulic connectivity between them. No appreciable seasonal change was observed in piezometric heads of the artesian wells, but the semi-artesian wells did show fluctuation of ~2 to 12 m during different years, which did not have any relation with the reservoir water levels. No considerable seasonal change in hydrochemistry was observed in individual wells due to the confined nature of the aquifers. The hydrochemical and δ18O data of the studied deep groundwaters and reservoir waters, being different from each other, rule out the possibility of direct hydraulic connectivity between them and surrounding groundwater (up to 250 m), even though favorable topographic conditions exist for linkage. The radiocarbon ages, being incomparable between different well waters, support the inference drawn from hydrochemistry and stable isotope data.

  12. The Seismic Wavefield

    NASA Astrophysics Data System (ADS)

    Kennett, B. L. N.

    2002-12-01

    The two volumes of The Seismic Wavefield are a comprehensive guide to the understanding of seismograms in terms of physical propagation processes within the Earth. The focus is on the observation of earthquakes and man-made sources on all scales, for both body waves and surface waves. Volume I provides a general introduction and a development of the theoretical background for seismic waves. Volume II looks at the way in which observed seismograms relate to the propagation processes. Volume II also discusses local and regional seismic events, global wave propagation, and the three-dimensional Earth.

  13. Petrologically-constrained thermo-chemical modelling of cratonic upper mantle consistent with elevation, geoid, surface heat flow, seismic surface waves and MT data

    NASA Astrophysics Data System (ADS)

    Jones, A. G.; Afonso, J. C.

    2015-12-01

    The Earth comprises a single physio-chemical system that we interrogate from its surface and/or from space making observations related to various physical and chemical parameters. A change in one of those parameters affects many of the others; for example a change in velocity is almost always indicative of a concomitant change in density, which results in changes to elevation, gravity and geoid observations. Similarly, a change in oxide chemistry affects almost all physical parameters to a greater or lesser extent. We have now developed sophisticated tools to model/invert data in our individual disciplines to such an extent that we are obtaining high resolution, robust models from our datasets. However, in the vast majority of cases the different datasets are modelled/inverted independently of each other, and often even without considering other data in a qualitative sense. The LitMod framework of Afonso and colleagues presents integrated inversion of geoscientific data to yield thermo-chemical models that are petrologically consistent and constrained. Input data can comprise any combination of elevation, geoid, surface heat flow, seismic surface wave (Rayleigh and Love) data and receiver function data, and MT data. The basis of LitMod is characterization of the upper mantle in terms of five oxides in the CFMAS system and a thermal structure that is conductive to the LAB and convective along the adiabat below the LAB to the 410 km discontinuity. Candidate solutions are chosen from prior distributions of the oxides. For the crust, candidate solutions are chosen from distributions of crustal layering, velocity and density parameters. Those candidate solutions that fit the data within prescribed error limits are kept, and are used to establish broad posterior distributions from which new candidate solutions are chosen. Examples will be shown of application of this approach fitting data from the Kaapvaal Craton in South Africa and the Rae Craton in northern Canada. I

  14. Looking for surface faulting ancestors of the L’Aquila April 6, 2009 event: preliminary paleoseismological data and seismic hazard implications

    NASA Astrophysics Data System (ADS)

    Cinti, F. R.; Civico, R.; Cucci, L.; de Martini, P.; Pantosti, D.; Pierdominici, S.; Pucci, S.; Brunori, C.; Fracassi, U.; Villani, F.

    2009-12-01

    The occurrence of the Mw 6.3, April 6, 2009 earthquake has highlighted how critical is the knowledge of the location and of the characteristics of the active faults in a seismic region. This is true not only as a contribution to the seismic hazard assessment but also for the local planning of residential areas, plants and infrastructures. The 2009 earthquake occurred on the Paganica normal fault (PF hereinafter) and produced 3 km-long, maximum 0.1 m-high surface rupture along its central section, and secondary slip along nearby tectonic structures. The PF consists of a prominent morphologic scarp formed by the tectonic juxtaposition of Pliocene-middle Pleistocene and late Pleistocene alluvial deposits, and by lower scarps in late Pleistocene-Holocene deposits. The fault, NW-SE striking and SW dipping, runs for a total length of about 20 km along the NE side of the Aterno River valley, a graben-type basin bounded by marked antithetic faults. The limited extent and the small throw of the 2009 surface ruptures, when compared to the size of the Paganica long-term fault scarp, suggest that the PF probably experienced larger Magnitude earthquakes than the 2009 seismic event. Thus, although the April 6, 2009 earthquake and associated surface faulting caused loss of lives and major damage, we believe that this event does not fully characterize the seismic hazard of the area. Therefore, a campaign of paleoseismological investigations is underway with the aim of defining the Max Magnitude, the average rate of displacement and the frequency of seismic events on the PF and on the nearby faults. An amazing “coseismic” trench, caved by the overpressure produced by the broken pipe of an aqueduct, provided the exposure of a 30-m wide fault zone of the PF. We show the preliminary results from the analysis of this site, as well as from other sites along the PF. In addition, we also present preliminary paleoseismological data from the antithetic Fossa fault. A major finding at

  15. Interplate and Intraplate Decoupling: A 3D View from Surface Geology and Seismicity, Eastern Hellenic Forearc, Greece

    NASA Astrophysics Data System (ADS)

    Kleinspehn, K. L.; Russo, R. M.

    2003-12-01

    Shallow active seismicity and neotectonic structures reveal important changes in the degree of interplate and intraplate coupling along the convergent Hellenic plate boundary from Crete to Rhodes. The onshore/offshore Pliocene-Holocene surface geology of the Hellenic forearc records three different deformation states: 1) A western segment (western Crete) where incipient continent-continent collision produces shortening under strong interplate coupling; 2) a central segment (central-eastern Crete) partly coupled to Africa where oblique convergence is partitioned into sinistral strike slip and orthogonal shortening which is confined to the accretionary wedge; and 3) an eastern trantensional segment (Rhodes), mechanically decoupled from African oblique convergence, instead reflecting slab rollback and Aegea's southward motion relative to Anatolia. Such along-strike heterogeneity of neotectonic structures suggests each segment should also display distinct crustal-scale stress patterns. Abundant earthquake focal mechanisms provide a means to gauge stress regimes. Shallowly plunging P (compression) and T (tension) axes of crustal events differ systematically along the three forearc segments. Above the brittle-ductile transition (<13 km), the western segment records N-S P axes and E-W T axes. In the central Crete transition zone, P and T axes vary, whereas sparse P axes in the decoupled eastern forearc (Rhodes) parallel the NNE plate margin. Below the brittle-ductile transition (13 < h < 40 km), P axes beneath western Crete trend N-S normal to the subduction trace, signifying interplate coupling given their similarity to plate-convergence vectors. T axes trend WNW consistent with margin-parallel extension at depth due to Africa's northward convergence. Stress patterns reverse for the wrench-dominated transition zone: P axes trend WNW-ESE and T axes trend N-S, indicating that northward convergence is less important than slab roll back. In the transtensional forearc east of

  16. Martian seismicity

    NASA Technical Reports Server (NTRS)

    Phillips, Roger J.; Grimm, Robert E.

    1991-01-01

    The design and ultimate success of network seismology experiments on Mars depends on the present level of Martian seismicity. Volcanic and tectonic landforms observed from imaging experiments show that Mars must have been a seismically active planet in the past and there is no reason to discount the notion that Mars is seismically active today but at a lower level of activity. Models are explored for present day Mars seismicity. Depending on the sensitivity and geometry of a seismic network and the attenuation and scattering properties of the interior, it appears that a reasonable number of Martian seismic events would be detected over the period of a decade. The thermoelastic cooling mechanism as estimated is surely a lower bound, and a more refined estimate would take into account specifically the regional cooling of Tharsis and lead to a higher frequency of seismic events.

  17. 3D modelling of the active normal fault network in the Apulian Ridge (Eastern Mediterranean Sea): Integration of seismic and bathymetric data with implicit surface methods

    NASA Astrophysics Data System (ADS)

    Bistacchi, Andrea; Pellegrini, Caludio; Savini, Alessandra; Marchese, Fabio

    2016-04-01

    The Apulian ridge (North-eastern Ionian Sea, Mediterranean), interposed between the facing Apennines and Hellenides subduction zones (to the west and east respectively), is characterized by thick cretaceous carbonatic sequences and discontinuous tertiary deposits crosscut by a penetrative network of NNW-SSE normal faults. These are exposed onshore in Puglia, and are well represented offshore in a dataset composed of 2D seismics and wells collected by oil companies from the '60s to the '80s, more recent seismics collected during research projects in the '90s, recent very high resolution seismics (VHRS - Sparker and Chirp-sonar data), multibeam echosounder bathymetry, and sedimentological and geo-chronological analyses of sediment samples collected on the seabed. Faults are evident in 2D seismics at all scales, and their along-strike geometry and continuity can be characterized with multibeam bathymetric data, which show continuous fault scarps on the seabed (only partly reworked by currents and covered by landslides). Fault scarps also reveal the finite displacement accumulated in the Holocene-Pleistocene. We reconstructed a 3D model of the fault network and suitable geological boundaries (mainly unconformities due to the discontinuous distribution of quaternary and tertiary sediments) with implicit surface methods implemented in SKUA/GOCAD. This approach can be considered very effective and allowed reconstructing in details complex structures, like the frequent relay zones that are particularly well imaged by seafloor geomorphology. Mutual cross-cutting relationships have been recognized between fault scarps and submarine mass-wasting deposits (Holocene-Pleistocene), indicating that, at least in places, these features are coeval, hence the fault network should be considered active. At the regional scale, the 3D model allowed measuring the horizontal WSW-ENE stretching, which can be associated to the bending moment applied to the Apulian Plate by the combined effect

  18. Integration of Well & Core Data of Carbonate Reservoirs with Surface Seismic in Garraf Oil Field, Southern Iraq

    NASA Astrophysics Data System (ADS)

    Mhuder, J. J.; Muhlhl, A. A.; Basra Geologiests

    2013-05-01

    The Garraf Field is situated in Southern Iraq in Nasiriya area, is located in Mesopotamian basin. The carbonate facies are dominant in main reservoirs in Garraf field (Mishrif and Yammama Formations) which is Cretaceous in age. The structure of the reservoir in this field are low relief gentle anticlinal structure aligned in NW to SE direction, and No fault were observed and interpreted in 3D seismic section. 3D seismic survey by Iraqi Oil Exploration Company No 2 was successfully conducted on the Garraf field at 2008-2009 using recording system SERCEL 408UL and Vibrators Nomad 65. Bin size: 25*25, Fold: 36, SP Interval: 50m, Lines Interval: 300m, 3 wells were drilled Ga (1, 2, 3) and it used for seismic to well tie in Petrel. Data analysis was conducted for each reservoirs for Lithological and sedimentological studies were based on core and well data .The study showed That the Mishrif Formation deposited in a broad carbonate platform with shallowing upward regressive succession and The depositional environment is extending from outer marine to shallow middle-inner shelf settings with restricted lagoons as supported by the present of Miliolid fossils. The fragmented rudist biostromes accumulated in the middle shelf. No rudist reef is presence in the studied cores. While the Major sequences are micritic limestone of lagoonal and oolitic/peloidal grainstone sandy shoal separated by mudstone of Yamama formation. Sedimentation feature are seen on seismic attributes and it is help for understanding of sedimentation environment and suitable structure interpretation. There is good relationship between Acustic Impedance and porosity, Acustic Impedance reflects porosity or facies change of carbonate rather than fluid content. Data input used for 3D Modeling include 3D seismic and AI data, petrophysical analysis, core and thin section description. 3D structure modeling were created base on the geophysical data interpretation and Al analysis. Data analysis for Al data were

  19. Surface Creep Along the East Anatolian Fault (Turkey) Revealed by InSAR Time Series: Implications for Seismic Hazard and Mechanism of Creep

    NASA Astrophysics Data System (ADS)

    Senturk, S.; Cakir, Z.; Ergintav, S.; Dogan, U.; Cetin, S.; Akoglu, A. M.; Meghraoui, M.; Karabulut, H.

    2015-12-01

    Forming the boundary between the Anatolian and Arabian plates in Turkey, the East Anatolian Fault (EAF) is a major tectonic structure in the Eastern Mediterranean region. Together with its conjugate, the North Anatolian Fault (NAF), it accommodates the westward motion of the Anatolian plate with respect to Eurasia. Although it has been associated only with small-to-moderate sized earthquakes in the instrumental period and relatively quiet compared to the North Anatolian Fault, the EAF produced devastating large (M > 7) earthquakes in the historical time (Ambraseys et al., 1998). Analysis of historical seismicity (Nalbant et al., 2001) suggests that a seismic gap exists between the Lake of Hazar and Bingöl, referred here as to Palu seismic gap (PSG) We estimate the interseismic velocity field along the BSG using the Persistent Scatterer InSAR technique (Hooper, 2008). ENVISAT ASAR data acquired between 2003 and 2010 on three adjacent descending and overlapping tracks (T035, T264 and T493) are use to map the interseismic strain accumulation. The results reveal that the 100-km-long section of the Palu segment is exhibiting aseismic creep at the surface. The creep rate varies along the fault reaching, at some places, to the far field GPS-based plate velocity (i.e., 10 ± 0.3 mm/y; Reilinger et al., 2006), implying that significant portion of the elastic strain has been released aseismically. Preliminary modelling with elastic dislocations suggests that some sections of the fault may be creeping from surface down to the entire seismogenic crust. Geology of the fault zone is dominated by ophiolitic and volcanic rocks characterized by weak phyllosilicate minerals, suggesting that aseismic slip is promoted by minerals with low frictional properties. Furthermore, to monitor the surface creep, a GPS network has been established along the Palu segment. One survey has so far been realized and we expect the reliable results in 2 years (supported by TUBITAK no: 114Y250 project).

  20. Surface wave attenuation in the shallow subsurface from multichannel-multishot seismic data: a new approach for detecting fractures and lithological discontinuities

    NASA Astrophysics Data System (ADS)

    Ikeda, Tatsunori; Tsuji, Takeshi

    2016-07-01

    Surface wave analysis generally neglects amplitude information, instead using phase information to delineate near-surface S-wave velocity structures. To effectively characterize subsurface heterogeneities from amplitude information, we propose a method of estimating lateral variation of attenuation coefficients of surface waves from multichannel-multishot (multifold) seismic data. We extend the concept of the common midpoint cross-correlation method, used for phase velocity estimation, to the analysis of attenuation coefficients. Our numerical experiments demonstrated that when used together, attenuation coefficients and phase velocities could characterize a lithological boundary as well as fracture zone. We applied the proposed method to multifold seismic reflection data acquired in Shikoku Island, Japan. We clearly observed abrupt changes in lateral variation of estimated attenuation coefficients around fault locations associated with a lithological boundary and with well-developed fractures, whereas phase velocity results could detect only the lithological boundary. Our study demonstrated that simultaneous interpretation of attenuation coefficients and phase velocities has the potential to distinguish localized fractures from lithological boundaries.

  1. Seismic Ecology

    NASA Astrophysics Data System (ADS)

    Seleznev, V. S.; Soloviev, V. M.; Emanov, A. F.

    The paper is devoted to researches of influence of seismic actions for industrial and civil buildings and people. The seismic actions bring influence directly on the people (vibration actions, force shocks at earthquakes) or indirectly through various build- ings and the constructions and can be strong (be felt by people) and weak (be fixed by sensing devices). The great number of work is devoted to influence of violent seismic actions (first of all of earthquakes) on people and various constructions. This work is devoted to study weak, but long seismic actions on various buildings and people. There is a need to take into account seismic oscillations, acting on the territory, at construction of various buildings on urbanized territories. Essential influence, except for violent earthquakes, man-caused seismic actions: the explosions, seismic noise, emitted by plant facilities and moving transport, radiation from high-rise buildings and constructions under action of a wind, etc. can exert. Materials on increase of man- caused seismicity in a number of regions in Russia, which earlier were not seismic, are presented in the paper. Along with maps of seismic microzoning maps to be built indicating a variation of amplitude spectra of seismic noise within day, months, years. The presence of an information about amplitudes and frequencies of oscillations from possible earthquakes and man-caused oscillations in concrete regions allows carry- ing out soundly designing and construction of industrial and civil housing projects. The construction of buildings even in not seismically dangerous regions, which have one from resonance frequencies coincident on magnitude to frequency of oscillations, emitted in this place by man-caused objects, can end in failure of these buildings and heaviest consequences for the people. The practical examples of detail of engineering- seismological investigation of large industrial and civil housing projects of Siberia territory (hydro power

  2. Refinements to the method of epicentral location based on surface waves from ambient seismic noise: introducing Love waves

    USGS Publications Warehouse

    Levshin, Anatoli L.; Barmin, Mikhail P.; Moschetti, Morgan P.; Mendoza, Carlos; Ritzwoller, Michael H.

    2012-01-01

    The purpose of this study is to develop and test a modification to a previous method of regional seismic event location based on Empirical Green’s Functions (EGFs) produced from ambient seismic noise. Elastic EGFs between pairs of seismic stations are determined by cross-correlating long ambient noise time-series recorded at the two stations. The EGFs principally contain Rayleigh- and Love-wave energy on the vertical and transverse components, respectively, and we utilize these signals between about 5 and 12 s period. The previous method, based exclusively on Rayleigh waves, may yield biased epicentral locations for certain event types with hypocentral depths between 2 and 5 km. Here we present theoretical arguments that show how Love waves can be introduced to reduce or potentially eliminate the bias. We also present applications of Rayleigh- and Love-wave EGFs to locate 10 reference events in the western United States. The separate Rayleigh and Love epicentral locations and the joint locations using a combination of the two waves agree to within 1 km distance, on average, but confidence ellipses are smallest when both types of waves are used.

  3. The double-lobed blazar 3C 371

    NASA Astrophysics Data System (ADS)

    Wrobel, J. M.; Lind, K. R.

    1990-01-01

    High dynamic range VLA imaging reveals, for the first time, that the blazar 3C 371 exhibits very low surface brightness twin radio lobes. These lobes straddle the dominant compact core and have a projected extent of about 42/h kpc. A weak component located in the western lobe shares the morphology, size, and inferred magnetic field configuration of radio source hot spots. A continuous wiggling jet connects this hot spot with the compact core. Double lobes, hot spots, and one-sided jets are traits of extended, edge-brightened radio sources. The discovery of corresponding components in 3C 371's extended emission suggests that this emission is an edge-brightened double, viewed at a large enough angle to the line of sight that the radio lobes do not overlap. A moderate viewing angle is consistent with 3C 371's low bolometric luminosity for a blazar. The diffuse radio halo that surrounds the twin lobes may be related to the fat bridges or bridge distortions shown by edge-brightened doubles with similar radio powers.

  4. Comparison of seismic sources for shallow seismic: sledgehammer and pyrotechnics

    NASA Astrophysics Data System (ADS)

    Brom, Aleksander; Stan-Kłeczek, Iwona

    2015-10-01

    The pyrotechnic materials are one of the types of the explosives materials which produce thermal, luminous or sound effects, gas, smoke and their combination as a result of a self-sustaining chemical reaction. Therefore, pyrotechnics can be used as a seismic source that is designed to release accumulated energy in a form of seismic wave recorded by tremor sensors (geophones) after its passage through the rock mass. The aim of this paper was to determine the utility of pyrotechnics for shallow seismic engineering. The work presented comparing the conventional method of seismic wave excitation for seismic refraction method like plate and hammer and activating of firecrackers on the surface. The energy released by various sources and frequency spectra was compared for the two types of sources. The obtained results did not determine which sources gave the better results but showed very interesting aspects of using pyrotechnics in seismic measurements for example the use of pyrotechnic materials in MASW.

  5. Fault zones ruptured during the early 2014 Cephalonia Island (Ionian Sea, Western Greece) earthquakes (January 26 and February 3, Mw 6.0) based on the associated co-seismic surface ruptures

    NASA Astrophysics Data System (ADS)

    Lekkas, Efthymios L.; Mavroulis, Spyridon D.

    2016-01-01

    The early 2014 Cephalonia Island (Ionian Sea, Western Greece) earthquake sequence comprised two main shocks with almost the same magnitude (moment magnitude (Mw) 6.0) occurring successively within a short time (January 26 and February 3) and space (Paliki peninsula in Western Cephalonia) interval. Εach earthquake was induced by the rupture of a different pre-existing onshore active fault zone and produced different co-seismic surface rupture zones. Co-seismic surface rupture structures were predominantly strike-slip-related structures including V-shaped conjugate surface ruptures, dextral and sinistral strike-slip surface ruptures, restraining and releasing bends, Riedel structures ( R, R', P, T), small-scale bookshelf faulting, and flower structures. An extensional component was present across surface rupture zones resulting in ground openings (sinkholes), small-scale grabens, and co-seismic dip-slip (normal) displacements. A compressional component was also present across surface rupture zones resulting in co-seismic dip-slip (reverse) displacements. From the comparison of our field geological observations with already published surface deformation measurements by DInSAR Interferometry, it is concluded that there is a strong correlation among the surface rupture zones, the ruptured active fault zones, and the detected displacement discontinuities in Paliki peninsula.

  6. Near Surface Structure of the Frijoles Strand of the San Gregorio Fault, Point Año Nuevo, San Mateo County, California, from Seismic Imaging

    NASA Astrophysics Data System (ADS)

    Campbell, L.; Catchings, R. D.; Rymer, M. J.; Goldman, M.; Weber, G. E.

    2012-12-01

    The San Gregorio Fault Zone (SGFZ) is one of the major faults of the San Andreas Fault (SAF) system in the San Francisco Bay region of California. The SGFZ is nearly 200 km long, trends subparallel to the SAF, and is located primarily offshore with two exceptions- between Point Año Nuevo and San Gregorio Beach and between Pillar Point and Moss Beach. It has a total width of 2 to 3 km and is comprised of seven known fault strands with Quaternary activity, five of which also demonstrate late Holocene activity. The fault is clearly a potential source of significant earthquakes and has been assigned a maximum likely magnitude of 7.3. To better understand the structure, geometry, and shallow-depth P-wave velocities associated with the SGFZ, we acquired a 585-m-long, high-resolution, combined seismic reflection and refraction profile across the Frijoles strand of the SGFZ at Point Año Nuevo State Park. Both P- and S-wave data were acquired, but here we present only the P-wave data. We used two 60-channel Geometrics RX60 seismographs and 120 40-Hz single-element geophones connected via cable to record Betsy Seisgun seismic sources (shots). Both shots and geophones were approximately co-located and spaced at 5-m intervals along the profile, with the shots offset laterally from the geophones by 1 m. We measured first-arrival refractions from all shots and geophones to develop a seismic refraction tomography velocity model of the upper 70 m. P-wave velocities range from about 600 m/s near the surface to more than 2400 m/s at 70 m depth. We used the refraction tomography image to infer the depth to the top of the groundwater table on the basis of the 1500 m/s velocity contour. The image suggests that the depth, along the profile, to the top of groundwater varies by about 18 m, with greater depth on the west side of the fault. At about 46 m depth, a 60- to 80-m-wide, low-velocity zone, which is consistent with faulting, is observed southwest of the Frijoles strand of the

  7. USING RECENT ADVANCES IN 2D SEISMIC TECHNOLOGY AND SURFACE GEOCHEMISTRY TO ECONOMICALLY REDEVELOP A SHALLOW SHELF CARBONATE RESERVOIR: VERNON FIELD, ISABELLA COUNTY, MI.

    SciTech Connect

    James R. Wood; T.J. Bornhorst; William B. Harrison; W. Quinlan

    2002-04-01

    The fault study continues to find more faults and develop new techniques to visualize them. Data from the Dundee Formation has been used to document 11 major faults in the Michigan Basin which have now been verified using data from other horizons. These faults control the locations of many of the large anticlinal structures in the Michigan Basin and likely controlled fluid movements as well. The surface geochemistry program is also moving along well with emphasis on measuring samples collected last sampling season. The new GC laboratory is now functional and has been fully staffed as of December. The annual project review was held March 7-9 in Tampa, Florida. Contracts are being prepared for drilling the Bower's prospects in Isabella County, Michigan, this spring or summer. A request was made to extend the scope of the project to include the Willison Basin. A demonstration well has been suggested in Burke County, N. Dakota, following a review of 2D seismic and surface geochem. A 3D seismic survey is scheduled for the prospect.

  8. CFD Growth of 3C-SiC on 4H/6H Mesas

    NASA Technical Reports Server (NTRS)

    Neudeck, Philip G.; Trunek, Andrew J.; Spry, David J.; Powell, J. Anthony; Du, Hui; Skowronski, Marek; Huang, XianRong; Dudley, Michael

    2006-01-01

    This article describes growth and characterization of the highest quality reproducible 3C-SiC heteroepitaxial films ever reported. By properly nucleating 3C-SiC growth on top of perfectly on-axis (0001) 4H-SiC mesa surfaces completely free of atomic scale steps and extended defects, growth of 3C-SiC mesa heterofilms completely free of extended crystal defects can be achieved. In contrast, nucleation and growth of 3C-SiC mesa heterofilms on top of 4H-SiC mesas with atomic-scale steps always results in numerous observable dislocations threading through the 3C-SiC epilayer. High-resolution X-ray diffraction and transmission electron microscopy measurements indicate non-trivial in-plane lattice mismatch between the 3C and 4H layers. This mismatch is somewhat relieved in the step-free mesa case via misfit dislocations confined to the 3C/4H interfacial region without dislocations threading into the overlying 3C-SiC layer. These results indicate that the presence or absence of steps at the 3C/4H heteroepitaxial interface critically impacts the quality, defect structure, and relaxation mechanisms of single-crystal heteroepitaxial 3C-SiC films.

  9. CVD Growth of 3C-SiC on 4H/6H Mesas

    SciTech Connect

    Neudeck,P.; Trunek, A.; Spry, D.; Powell, J.; Du, H.; Skowronski, M.; Huang, X.; Dudley, M.

    2006-01-01

    This article describes growth and characterization of the highest quality reproducible 3C-SiC heteroepitaxial films ever reported. By properly nucleating 3C-SiC growth on top of perfectly on-axis (0001) 4H-SiC mesa surfaces completely free of atomic scale steps and extended defects, growth of 3C-SiC mesa heterofilms completely free of extended crystal defects can be achieved. In contrast, nucleation and growth of 3C-SiC mesa heterofilms on top of 4H-SiC mesas with atomic-scale steps always results in numerous observable dislocations threading through the 3C-SiC epilayer. High-resolution X-ray diffraction (HRXRD) and high resolution cross-sectional transmission electron microscopy (HRXTEM) measurements indicate non-trivial, in-plane, lattice mismatch between the 3C and 4H layers. This mismatch is somewhat relieved in the step-free mesa case via misfit dislocations confined to the 3C/4H interfacial region without dislocations threading into the overlying 3C-SiC layer. These results indicate that the presence or absence of steps at the 3C/4H heteroepitaxial interface critically impacts the quality, defect structure, and relaxation mechanisms of single-crystal heteroepitaxial 3C-SiC films.

  10. Calculation of zero-offset vertical seismic profiles generated by a horizontal point force acting on the surface of an elastic half-space

    USGS Publications Warehouse

    Hsi-Ping, Liu

    1990-01-01

    Impulse responses including near-field terms have been obtained in closed form for the zero-offset vertical seismic profiles generated by a horizontal point force acting on the surface of an elastic half-space. The method is based on the correspondence principle. Through transformation of variables, the Fourier transform of the elastic impulse response is put in a form such that the Fourier transform of the corresponding anelastic impulse response can be expressed as elementary functions and their definite integrals involving distance angular frequency, phase velocities, and attenuation factors. These results are used for accurate calculation of shear-wave arrival rise times of synthetic seismograms needed for data interpretation of anelastic-attenuation measurements in near-surface sediment. -Author

  11. Controllable seismic source

    SciTech Connect

    Gomez, Antonio; DeRego, Paul Jeffrey; Ferrell, Patrick Andrew; Thom, Robert Anthony; Trujillo, Joshua J.; Herridge, Brian

    2015-09-29

    An apparatus for generating seismic waves includes a housing, a strike surface within the housing, and a hammer movably disposed within the housing. An actuator induces a striking motion in the hammer such that the hammer impacts the strike surface as part of the striking motion. The actuator is selectively adjustable to change characteristics of the striking motion and characteristics of seismic waves generated by the impact. The hammer may be modified to change the physical characteristics of the hammer, thereby changing characteristics of seismic waves generated by the hammer. The hammer may be disposed within a removable shock cavity, and the apparatus may include two hammers and two shock cavities positioned symmetrically about a center of the apparatus.

  12. Controllable seismic source

    SciTech Connect

    Gomez, Antonio; DeRego, Paul Jeffrey; Ferrel, Patrick Andrew; Thom, Robert Anthony; Trujillo, Joshua J.; Herridge, Brian

    2014-08-19

    An apparatus for generating seismic waves includes a housing, a strike surface within the housing, and a hammer movably disposed within the housing. An actuator induces a striking motion in the hammer such that the hammer impacts the strike surface as part of the striking motion. The actuator is selectively adjustable to change characteristics of the striking motion and characteristics of seismic waves generated by the impact. The hammer may be modified to change the physical characteristics of the hammer, thereby changing characteristics of seismic waves generated by the hammer. The hammer may be disposed within a removable shock cavity, and the apparatus may include two hammers and two shock cavities positioned symmetrically about a center of the apparatus.

  13. DOBRE-2000: Deep Reflection Seismic, Gravimetric and Surface Structural Controls Across a Devonian Failed Rift in the Southeastern Europe

    NASA Astrophysics Data System (ADS)

    Roy-Chowdhury, K.; Bayer, U.; Gajewski, D.; Huebscher, C.; Rabbel, W.; Saintot, A.; Starostenko, V. I.; Stephenson, R.; Stovba, S. M.; Tolkunov, A.; Thybo, H.

    2001-12-01

    Situated between the Ukrainian Shield and the Voronezh Masif, the Pripyat-Dniepr-Donets Basin (PDD) is a crustal-scale geodynamic feature associated with the Late Devonian rifting of the East European Craton. The Donbas Foldbelt (DF), comprising the eastern part of the PDD, includes pre- & syn-rift deposits below a large thickness of post-rift successions. Later, DF has been inverted (elevated, eroded, deformed). With 20+ km of sediments, it has a large economic potential, but its tectonic history - and the cause for its isolated evolution - is not well understood. Recently, 130+ km multi-channel reflection seismic profiling data has been acquired across the southern part of the DF in the framework of an international industry-academic collaboration. Coincident gravity data has been collected along the profile too, and extensive structural studies have been carried out to understand the spatio-temporal distribution of the stress-regime in the area. The high-resolution seismic images reveal an extensive stair-step like fragmentation of the basement including faults with upto 2km offset. The typical size of these "steps" are influenced by the ambient conditions at the time of their formation. Combined use of the different datasets is expected to shed light on several intriguing features associated with DF. The presence/extent of salt, causing localization and/or partition of strain both laterally and vertically, may be studied by using its seismic and gravitational reponses simultaneously. The interaction between the lower crust and the upper mantle may also be studied in the same manner, which should result in a lithological interpretation at depth favoring in turn one of the causative mechanisms.

  14. Multiwavelength observations of giant radio galaxy 3C 35 and 3C 284

    NASA Astrophysics Data System (ADS)

    Pal, Sabyasachi; Chakrabarti, Sandip Kumar; Patra, Dusmanta; Konar, Chiranjib

    2016-07-01

    We report multi wavelength observations of large radio galaxy 3C35 and 3C284. The low frequency observations were done with the Giant Metrewave Radio Telescope (GMRT) starting from 150 MHz. The high frequency observations were done with Jansky Very Large Array (JVLA). Our main motivation for these observations is to estimate the spectral ages of these galaxies and to examine any proof of extended emission at low radio frequencies due to an earlier cycle of activity. The spectral age is measured by fitting the spectra with different spectral ageing models e.g. Kardashev-Pacholczyk (KP), Jaffe-Perola (JP) and Continuous Injection (CI).

  15. Seismic monitoring of geomorphic processes

    NASA Astrophysics Data System (ADS)

    Burtin, A.; Hovius, N.; Turowski, J. M.

    2014-12-01

    In seismology, the signal is usually analysed for earthquake data, but these represent less than 1% of continuous recording. The remaining data are considered as seismic noise and were for a long time ignored. Over the past decades, the analysis of seismic noise has constantly increased in popularity, and this has led to develop new approaches and applications in geophysics. The study of continuous seismic records is now open to other disciplines, like geomorphology. The motion of mass at the Earth's surface generates seismic waves that are recorded by nearby seismometers and can be used to monitor its transfer through the landscape. Surface processes vary in nature, mechanism, magnitude and space and time, and this variability can be observed in the seismic signals. This contribution aims to give an overview of the development and current opportunities for the seismic monitoring of geomorphic processes. We first describe the common principles of seismic signal monitoring and introduce time-frequency analysis for the purpose of identification and differentiation of surface processes. Second, we present techniques to detect, locate and quantify geomorphic events. Third, we review the diverse layout of seismic arrays and highlight their advantages and limitations for specific processes, like slope or channel activity. Finally, we illustrate all these characteristics with the analysis of seismic data acquired in a small debris-flow catchment where geomorphic events show interactions and feedbacks. Further developments must aim to fully understand the richness of the continuous seismic signals, to better quantify the geomorphic activity and improve the performance of warning systems. Seismic monitoring may ultimately allow the continuous survey of erosion and transfer of sediments in the landscape on the scales of external forcing.

  16. Near-surface seismic velocity changes in a salt-dominated environment due to shaking and thermal stressing

    NASA Astrophysics Data System (ADS)

    Richter, Tom; Sens-Schönfelder, Christoph; Kind, Rainer; Asch, Günter

    2014-05-01

    We report on results from a seismic station of the Integrated Plate Boundary Observatory Chile (IPOC) showing a superior sensitivity of seismic velocity changes in the surrounding medium to shaking and temperature. 5 years of daily autocorrelations of the IPOC network are analyzed with passive image interferometry. Due to the particular geological conditions we observe a high sensitivity of the medium around the station near Patache (PATCX) resulting in annual periodic velocity variations and temporary velocity reductions induced by ground shaking. We observe a linear relationship between the amplitude of the velocity reductions and the peak ground acceleration (PGA) of nearby earthquakes at station PATCX. Although velocity reductions are also observed at other stations of the IPOC array for the Mw 7.7 Tocopilla earthquake a clear relationship between the PGA of this earthquake and the induced velocity reductions at the different stations is not visible. Furthermore, we observe velocity variations with an annual and daily period. We present different arguments that these periodic changes are caused by variations of the atmospheric temperature. In this context we construct a model that starts at observed temperature variations and evaluates thermal stresses induced by the temperature gradients. Using radiative transfer based sensitivity kernels and third order elastic constants we relate the distribution of thermal stress in the subsurface to observable time shifts of coda waves. The model is able to reproduce the major features confirming that stress changes in the subsurface can be detected with noise based monitoring.

  17. Multifrequency Monitoring of 3C 120, 3C 279, and PKS 1510--089

    NASA Technical Reports Server (NTRS)

    Jorstad, S. G.; Marscher, A. P.; Aller, M. F.; Balonek, T. J.; Gomez, J.-L.; McHardy, I. M.; Terasranta, H.; Raiteri, C.; Tosti, G.

    2001-01-01

    We analyze contemporaneous X-ray, optical, and radio light curves of 3C 120, ABC 279, and PKS 1510-089 on timescales from a few to hundreds of days over a 3-5 year period. The results show the diverse connections between variability properties at different frequencies for different blazers.

  18. The resolved outflow from 3C 48

    SciTech Connect

    Shih, Hsin-Yi; Stockton, Alan E-mail: stockton@ifa.hawaii.edu

    2014-10-20

    We investigate the properties of the high-velocity outflow driven by the young radio jet of 3C 48, a compact-steep-spectrum source. We use the Space Telescope Imaging Spectrograph on board the Hubble Space Telecope to obtain (1) low-resolution UV and optical spectra and (2) multi-slit medium-resolution spectra of the ionized outflow. With supporting data from ground-based spectrographs, we are able to accurately measure the ratios of diagnostic emission lines such as [O III] λ5007, [O III] λ3727, [N II] λ6548, Hα, Hβ, [Ne V] λ3425, and [Ne III] λ3869. We fit the observed emission-line ratios using a range of ionization models, powered by active galactic nucleus (AGN) radiation and shocks, produced by the MAPPINGS code. We have determined that AGN radiation is likely the dominant ionization source. The outflow's density is estimated to be in the range n = 10{sup 3}-10{sup 4} cm{sup –3}, the mass is ∼6 × 10{sup 6} M {sub ☉}, and the metallicity is likely equal to or higher than solar. Compared with the typical outflows associated with more evolved radio jets, this young outflow is denser, less massive, and more metal rich. Multi-slit observations allow us to construct a two-dimensional velocity map of the outflow that shows a wide range of velocities with distinct velocity components, suggesting a wide-angle clumpy outflow.

  19. Elastic Wavespeed Images of Northern Chile Subduction Zone from the Joint Inversion of Body and Surface Waves: Structure of the Andean Forearc and the Double Seismic Zone

    NASA Astrophysics Data System (ADS)

    Comte, D.; Carrizo, D.; Roecker, S. W.; Peyrat, S.; Arriaza, R.; Chi, R. K.; Baeza, S.

    2015-12-01

    Partly in anticipation of an imminent megathrust earthquake, a significant amount of seismic data has been collected over the past several years in northern Chile by local deployments of seismometers. In this study we generate elastic wavespeed images of the crust and upper mantle using a combination of body wave arrival times and surface wave dispersion curves. The body wave data set consists of 130000 P and 108000 S wave arrival times generated by 12000 earthquakes recorded locally over a period of 25 years by networks comprising about 360 stations. The surface wave data set consists of Rayleigh wave dispersion curves determined from ambient noise recorded by 60 broad band stations from three different networks over a period of three years. Transit time biases due to an uneven distribution of noise were estimated using a technique based on that of Yao and van der Hilst (2009) and found to be as high as 5% for some station pairs. We jointly invert the body and surface wave observations to both improve the overall resolution of the crustal images and reduce the trade-off between shallow and deep structures in the images of the subducted slab. Of particular interest in these images are three regions of anomalous Vp/Vs: (1) An extensive zone of low Vp/Vs (1.68) correlates with trench-parallel magmatic belts emplaced in the upper continental crust. In the region of the coast and continental slope, low Vp/Vs corresponds to batholithic structures in the Jurassic-Cretaceous magmatic arc. Between the central depression and Domeyko Cordillera, low Vp/Vs correlates with the distribution of magmatic arcs of Paleocene-Oligocene and Eocene-Oligocene age. Low Vp/Vs also correlates with the location of the Mejillones Peninsula. (2) A region of high Vp/Vs occurs in what is most likely the serpentinized wedge of the subduction zone. (3) An additional zone of low Vp/Vs is located in the middle of the double seismic zone at depths of 90-110 km. This region may exist all along the

  20. From the Surface Topography to the Upper Mantle Beneath Central-Iberian-Zone. the Alcudia Seismic Experiments.

    NASA Astrophysics Data System (ADS)

    Carbonell, R.; Ehsan, S. A.; Ayarza, P.; Martinez-Poyatos, D. J.; Simancas, J. F.; Azor, A.; Pérez-Estaún, A.

    2014-12-01

    Normal incidence and wide-angle seismic reflection data acquired in the Central and southern parts of the Iberia Peninsula resolve the internal architecture and constrain the distribution of the physical properties along an almost 350 km long transect that samples the major tectonic domains of the Iberian Massif, including the Central Iberian Zone (CIZ) and the associated sutures. The internal architecture down to almost 70 km depth (~15 s TWTT) is resolved by the normal incidence data set. It images a number of elements that characterize the tectonics of the study area, which is one of the best exposed fragment of the Variscan orogenic Belt. A well marked brittle-to-ductile (B2D) transition separates the crust in two, the upper and mid-lower parts, approximately, 13 km and 18 km thick, respectively. The upper crust appears to be decoupled from the mid-lower crust and responded differently to shortening. The Mohorovicic discontinuity is located at ~10.5 s (TWTT) , it is relatively thick, and highly reflective beneath the CIZ. The wide-angle seismic transect extended the lithospheric section towards the north across the Madrid Basin. This profile provides very strong constraints on the distribution of physical properties (P- and S- wave velocities, Poisson's ratio) of the upper lithosphere as well as a high resolution image of the base of the crust beneath the area. This data is one of the first datasets to present solid evidence of a relatively significant crustal thickening beneath the Madrid Basin. The crustal thickness varies from ~31 km beneath the CIZ to ~35.5 km beneath the Madrid Basin. This data set also reveals two major discontinuity levels, the B2D and the Moho, both represent levels of lithological/rheological variations. The characteristics of the the PmP and SmS seismic phases suggest further details on the internal structure of the Moho. Furthermore, low fold wide-angle P and S wave stacks reveal a marked crust-mantle transition which is most

  1. Photosynthesis of C3, C3-C4, and C4 grasses at glacial CO2.

    PubMed

    Pinto, Harshini; Sharwood, Robert E; Tissue, David T; Ghannoum, Oula

    2014-07-01

    Most physiology comparisons of C3 and C4 plants are made under current or elevated concentrations of atmospheric CO2 which do not reflect the low CO2 environment under which C4 photosynthesis has evolved. Accordingly, photosynthetic nitrogen (PNUE) and water (PWUE) use efficiency, and the activity of the photosynthetic carboxylases [Rubisco and phosphoenolpyruvate carboxylase (PEPC)] and decarboxylases [NADP-malic enzyme (NADP-ME) and phosphoenolpyruvate carboxykinase (PEP-CK)] were compared in eight C4 grasses with NAD-ME, PCK, and NADP-ME subtypes, one C3 grass, and one C3-C4 grass grown under ambient (400 μl l(-1)) and glacial (180 μl l(-1)) CO2. Glacial CO2 caused a smaller reduction of photosynthesis and a greater increase of stomatal conductance in C4 relative to C3 and C3-C4 species. Panicum bisulcatum (C3) acclimated to glacial [CO2] by doubling Rubisco activity, while Rubisco was unchanged in Panicum milioides (C3-C4), possibly due to its high leaf N and Rubisco contents. Glacial CO2 up-regulated Rubisco and PEPC activities in concert for several C4 grasses, while NADP-ME and PEP-CK activities were unchanged, reflecting the high control exerted by the carboxylases relative to the decarboxylases on the efficiency of C4 metabolism. Despite having larger stomatal conductance at glacial CO2, C4 species maintained greater PWUE and PNUE relative to C3-C4 and C3 species due to higher photosynthetic rates. Relative to other C4 subtypes, NAD-ME and PEP-CK grasses had the highest PWUE and PNUE, respectively; relative to C3, the C3-C4 grass had higher PWUE and similar PNUE at glacial CO2. Biomass accumulation was reduced by glacial CO2 in the C3 grass relative to the C3-C4 grass, while biomass was less reduced in NAD-ME grasses compared with NADP-ME and PCK grasses. Under glacial CO2, high resource use efficiency offers a key evolutionary advantage for the transition from C3 to C4 photosynthesis in water- and nutrient-limited environments.

  2. 2008 Wen-Chuan Mw 8.3 Earthquake: Dynamic Deformation Analysis for Seismic Surface Waveforms with 1-Hz GPS PPP Results

    NASA Astrophysics Data System (ADS)

    Shi, C.; Lou, Y.; Zhang, H.; Zhao, Q.; Liu, J.

    2008-12-01

    Some 1-Hz GPS data in China during Sichuan Wen-Chuan Mw8.3 Earthquake are processed with instantaneous Precise Point Positioning (PPP) technique using software PANDA developed in Wuhan University. Near-field GPS stations are located 30km away but lost data after 10s while several far-field sites are 300km~1200km away from epicenter. Results indicate that plane displacements exceed 40cm within 10seconds in near field while the post-seismic deformation is northwestward at the magnitude of around 30cm. Seismic surface waveforms as LOVE and Rayleigh waves can be seen clearly in the dynamic deformation process of station XANY and CHGO (in KunMing city, Yunnan Province). Love wave's first vibration is in northwestward and then southeastward, after about one cycle, Rayleigh wave comes. Love wave is at the speed of about 4km/s, Rayleigh's is about 2.85km/s. There are two deformation pulses in Rayleigh waveforms during the period of about 120 seconds monitored at station XANY, which is about 600km from epicenter. One pulse is in counter-clockwise movement and the other is clock-wise, which seems to reveal the fact that there are two kinds of rupture process in totally opposite direction. Spectral analysis shows that there are mainly two kinds of periods in the surface waves reflected by the 1-Hz horizontal deformations, one is about 5~10s (6s and 8s) and another is about 20s, corresponding to Rayleigh and Love wave respectively. Rayleigh's wavelength is about 20km, which indicates that the hypocenter is about in the depth of 10km.

  3. Development of an Adaptive Multi-Method Algorithm for Automatic Picking of First Arrival Times: Application to Near Surface Seismic Data

    NASA Astrophysics Data System (ADS)

    Khalaf, A.; Camerlynck, C. M.; Schneider, A. C.; Florsch, N.

    2015-12-01

    Accurate picking of first arrival times plays an important role in many seismic studies, particularly in seismic tomography and reservoirs or aquifers monitoring. Many techniques have been developed for picking first arrivals automatically or semi-automatically, but most of them were developed for seismological purposes which does not attain the accuracy objectives due to the complexity of near surface structures, and to usual low signal-to-noise ratio. We propose a new adaptive algorithm for near surface data based on three picking methods, combining multi-nested windows (MNW), Higher Order Statistics (HOS), and Akaike Information Criterion (AIC). They exploit the benefits of integrating many properties, which reveal the presence of first arrivals, to provide an efficient and robust first arrivals picking. This strategy mimics the human first-break picking, where at the beginning the global trend is defined. Then the exact first-breaks are searched in the vicinity of the now defined trend. In a multistage algorithm, three successive phases are launched, where each of them characterize a specific signal property. Within each phase, the potential picks and their error range are automatically estimated, and then used sequentially as leader in the following phase picking. The accuracy and robustness of the implemented algorithm are successfully validated on synthetic and real data which have special challenges for automatic pickers. The comparison of resulting P-wave arrival times with those picked manually, and other algorithms of automatic picking, demonstrated the reliable performance of the new scheme under different noisy conditions. All parameters of our multi-method algorithm are auto-adaptive thanks to the integration in series of each sub-algorithm results in the flow. Hence, it is nearly a parameter-free algorithm, which is straightforward to implement and demands low computational resources.

  4. New Refined VP, VS, and VP/VS Seismic Tomography of Taiwan Orogen with Near-surface Correction (PS logging data)

    NASA Astrophysics Data System (ADS)

    Huang, H.; Wu, Y.; Song, X.; Chang, C.; Lee, S.; Chang, T.; Hsieh, H.

    2012-12-01

    The tectonic model for Taiwan orogen has been long debated. Numerous tomographic studies undertaken in past decades were proposed but also tangled with part arguments. To further anatomize, the aid from the Vp/Vs ratio could be crucial; however, there were few Vp/Vs models for the entire Taiwan region in lithospheric scale. Therefore, with this attempt the New Vp, Vs, and Vp/Vs models for the crust-to-upper mantle structures of Taiwan orogeny contributed by a dense integrated seismic network and various data types, e.g. explosion data, S-P times, and PS logging data (VS30 and VP30), are determined. Through a well-designed scheme and the dynamic ratio bonding method (DRB) proposed in this study, we are able to simultaneously refine the Vp/Vs ratios during the inversion of P- and S-wave velocities. We also implement a near-surface correction employing the PS logging data to constrain the velocities at very shallow part, where the ray paths are usually subvertical and out of resolvability. In the meantime, the reported telemetry delays of Central Weather Bureau seismic network (CWBSN) are also considered and redeemed for the accuracy of inversion. The results show that our designed scheme could better improve and sharpen the tomographic images, exhibiting the clearer pattern and more details for subduction zones and mountain roots under the Central Range. The near-surface correction is tested to have significant effects on not only the shallow but deep structures and is encouraged to future studies. Furthermore, our derived Vp/Vs images reveal the distinct feature for Philippine Sea Pate but a complication under the orogen. Under the Central Range the Vp/Vs ratio at lower crust and upper mantle varies along the tectonic trend (ca. N20°E) from south to north, implying the materials changing or exoticism involved.

  5. THE ACCELERATING JET OF 3C 279

    SciTech Connect

    Bloom, S. D.; Fromm, C. M.; Ros, E.

    2013-01-01

    Analysis of the proper motions of the subparsec scale jet of the quasar 3C 279 at 15 GHz with the Very Long Baseline Array shows significant accelerations in four of nine superluminal features. Analysis of these motions is combined with the analysis of flux density light curves to constrain values of Lorentz factor and viewing angle (and their derivatives) for each component. The data for each of these components are consistent with significant changes to the Lorentz factor, viewing angle, and azimuthal angle, suggesting jet bending with changes in speed. We see that for these observed components Lorentz factors are in the range {Gamma} = 10-41, viewing angles are in the range thetav = 0. Degree-Sign 1-5. Degree-Sign 0, and intrinsic (source frame) flux density is in the range, F{sub {nu},int} 1.5 Multiplication-Sign 10{sup -9}-1.5 Multiplication-Sign 10{sup -5} Jy. Considering individual components, the Lorentz factors vary from {Gamma} = 11-16 for C1, {Gamma} = 31-41 for C5, {Gamma} = 29-41 for C6, and {Gamma} = 9-12 for C8, indicating that there is no single underlying flow speed to the jet and likely we are seeing pattern speeds from shocks in the jet. The viewing angles vary in time from 0. Degree-Sign 6 to 1. Degree-Sign 5 in the case of C1 (the least extreme example), from 0. Degree-Sign 5 to 5. Degree-Sign 0 in the case of C8, and from 0. Degree-Sign 1 to 0. Degree-Sign 9 for C5 (the last two being the most extreme examples). The intrinsic flux density varies by factors from 1.4 for C8 and 430 for C5. Theoretical analysis of the accelerations also indicates potential jet bending. In addition, for one component, C5, polarization measurements also set limits to the trajectory of the jet.

  6. The Resolved Outflow from 3C 48

    NASA Astrophysics Data System (ADS)

    Shih, Hsin-Yi; Stockton, Alan

    2014-10-01

    We investigate the properties of the high-velocity outflow driven by the young radio jet of 3C 48, a compact-steep-spectrum source. We use the Space Telescope Imaging Spectrograph on board the Hubble Space Telecope to obtain (1) low-resolution UV and optical spectra and (2) multi-slit medium-resolution spectra of the ionized outflow. With supporting data from ground-based spectrographs, we are able to accurately measure the ratios of diagnostic emission lines such as [O III] λ5007, [O III] λ3727, [N II] λ6548, Hα, Hβ, [Ne V] λ3425, and [Ne III] λ3869. We fit the observed emission-line ratios using a range of ionization models, powered by active galactic nucleus (AGN) radiation and shocks, produced by the MAPPINGS code. We have determined that AGN radiation is likely the dominant ionization source. The outflow's density is estimated to be in the range n = 103-104 cm-3, the mass is ~6 × 106 M ⊙, and the metallicity is likely equal to or higher than solar. Compared with the typical outflows associated with more evolved radio jets, this young outflow is denser, less massive, and more metal rich. Multi-slit observations allow us to construct a two-dimensional velocity map of the outflow that shows a wide range of velocities with distinct velocity components, suggesting a wide-angle clumpy outflow. Based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program GO-11574. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Some of the

  7. 3-component high resolution seismic profiling, a more holistic approach

    NASA Astrophysics Data System (ADS)

    Pugin, A.; Pullan, S. E.; Hunter, J. A.; Cartwright, T.; Brewer, K.; Near Surface Geophysics

    2011-12-01

    High resolution seismic reflection methods have been extensively used throughout Canada by the Geological Survey of Canada to map buried valleys and thick unconsolidated sediment for groundwater and engineering studies. Our acquisition system consists of a landstreamer array of 48, 3-component (3-C), 30 Hz geophones mounted on sleds spaced at 0.75 m, 1.5 m or 3 m. The system is towed by a Minivib I that generates a swept signal from 20 Hz to 350 Hz at source spacings varying between 3 and 6 m. The source spacing chosen depends on the survey objectives, including the target depth and the horizontal coverage required. With these recording parameters, we typically acquire 4 to 6 line-km of data per day, making this technique a viable and cost-effective tool for regional surveying. In a single acquisition pass, the 3-C recording system has the advantage of acquiring P-wave, converted PS-wave and S-wave data. As expected, P-wave data are always best recorded on the vertical component; however, the PS and the S-wave data show various directions of polarisation from vertical to horizontal. We have observed that the velocity characteristics of the ground are a more important factor in the reflection phase polarisation than the orientation of the vibrating mass of the Minivib source. In low shear-wave velocity sediments, the polarisation of the S-wave can evolve from sub-vertical in the near surface to almost horizontal for reflections from higher-velocity sediments or bedrock, irrespective of the source orientation. In more consolidated sediments characterized by higher near surface velocities, the polarisation phase of the S-wave remains predominantly horizontal from surface to bedrock even when the source is vibrated in the vertical mode. The acquisition of 3-C shallow seismic reflection data is providing new insights into the complex behaviour and polarisation of seismic energy in the subsurface, and opening new opportunities for improving the resolution and information

  8. Seismic seiches

    USGS Publications Warehouse

    McGarr, Arthur; Gupta, Harsh K.

    2011-01-01

    Seismic seiche is a term first used by Kvale (1955) to discuss oscillations of lake levels in Norway and England caused by the Assam earthquake of August 15, 1950. This definition has since been generalized to apply to standing waves set up in closed, or partially closed, bodies of water including rivers, shipping channels, lakes, swimming pools and tanks due to the passage of seismic waves from an earthquake.

  9. High-Frequency Seismic Waves generated by Building-Shaking Experiments and Surface Wave Group Velocity Estimates from the Cross-Correlation of Data

    NASA Astrophysics Data System (ADS)

    Tanimoto, T.; Okamoto, T.

    2013-12-01

    Modeling high-frequency (>1 Hz) seismic waves is known to be difficult but it is extremely important for earthquake hazard mitigation as many buildings have resonant frequencies above 1 Hz. In this study, we examine high-frequency waves at 1.64 Hz, generated by building-shaking experiments in California. The specific data we will examine are seismic data generated by shaking experiments of the Millikan Library between 2000 and 2002, located on the campus of California Institute of Technology in Pasadena, California. The excited wavefields were recorded by the broadband seismic network in the region (~150 stations), Southern California Seismic Network (SCSN). There were about 60 stations with good signal-to-noise ratios among SCSN stations. The maximum distance for signal detection was 323 km (station GRA). Based on numerical calculations for a regional seismic structure model (SCEC Community Velocity Model 11.9), we can show that the signals are dominated by surface waves (at 1.11 Hz and 1.64 Hz), whose energy is confined to shallow depths. The focus of this report will be on the cross-correlated signals between a station in the building (station MIK) and other stations. This cross-correlation may be viewed as a source deconvolution process and will let us focus on propagation in the medium. This cross-correlated phase can be expressed as a line integral of wavenumber along a propagation path for a direct (ballistic) phase, although it may contain complexity from the caustics (the Maslov index). Somewhat to our surprise, despite the fact that we are dealing with high frequency waves (1.64 Hz), we observe well-defined constant phase in many cross-correlated seismograms. If we knew the number of cycles between the source (Millikan) and a station, we could estimate phase velocity in principle but this is not possible and seems extremely hard because the number of cycles is about 50-100 or more. However, our signals do show frequency-dependence within a narrow (signal

  10. USING RECENT ADVANCES IN 2D SEISMIC TECHNOLOGY AND SURFACE GEOCHEMISTRY TO ECONOMICALLY REDEVELOP A SHALLOW SHELF CARBONATE RESERVOIR: VERNON FIELD, ISABELLA COUNTY, MI

    SciTech Connect

    James R. Wood; A. Wylie; W. Quinlan

    2004-10-01

    One of the principal objectives of this demonstration project is to test surface geochemical techniques for detecting trace amounts of light hydrocarbons in pore gases as a means of reducing risk in hydrocarbon exploration and production. During this reporting period, microbial samples were collected from the Trusty Steed prospect area in Grand Traverse County, Michigan. The samples were analyzed using the Microbial Oil Surveying Technique (MOST) technique and revealed only a local (1-point) anomaly. A decision to resample over that point is pending, but drilling has been postponed for the time being. The main news this reporting period is that in the Bear Lake area, northwest Michigan, Federated Oil & Gas Properties' Charlich-Fauble 2-9HD horizontal lateral, has cumulative production of more than 72,000 barrels of oil and is still producing 50 to 75 bopd from a Silurian Niagaran reef reservoir eighteen months after the well was completed. Surface geochemical surveys conducted in the demonstration area were consistent with production results although the ultimate decision to drill was based on interpretation of conventional subsurface and 2D seismic data. The surface geochemical techniques employed were Solid Phase MicroExtraction (SPME) and MOST. The geochemical results have been submitted to World Oil for publication. New geochemical surveys are planned for November in the Springdale quadrangle in Manistee County, Michigan. These surveys will concentrate on sampling over the trace of the proposed horizontal wells rather than a broad grid survey.

  11. USING RECENT ADVANCES IN 2D SEISMIC TECHNOLOGY AND SURFACE GEOCHEMISTRY TO ECONOMICALLY REDEVELOP A SHALLOW SHELF CARBONATE RESERVOIR: VERNON FIELD, ISABELLA COUNTY, MI.

    SciTech Connect

    James R. Wood; W. Quinlan

    2003-07-01

    The principal objective of this demonstration project is to test surface geochemical techniques for detecting trace amounts of light hydrocarbons in pore gases as a means of reducing risk in hydrocarbon exploration and production. As part of the project, a field demonstration was undertaken to assess the validity and usefulness of the microbial surface geochemical technique. The surface geochemistry data showed a strong anomaly in the Myrtle Beach area that would justify drilling by itself and even more so in conjunction with the structural interpretation from the 3D seismic data. The Myrtle Beach geochemical survey indicated a good to excellent prospect which was confirmed by drilling. Presented in this quarterly report is the Case History and Well Summary for the Myrtle Beach area in Burke County, North Dakota. This case history presents the important technical details regarding the geochemistry and the two vertical wells that are part of this field demonstration, and the applicability of these results to other demonstration projects. This format could be duplicated for other demonstration projects and is being used on all subsequent field demonstrations as they near completion.

  12. Seismic bearing

    NASA Astrophysics Data System (ADS)

    Power, Dennis

    2009-05-01

    Textron Systems (Textron) has been using geophones for target detection for many years. This sensing capability was utilized for detection and classification purposes only. Recently Textron has been evaluating multiaxis geophones to calculate bearings and track targets more specifically personnel. This capability will not only aid the system in locating personnel in bearing space or cartesian space but also enhance detection and reduce false alarms. Textron has been involved in the testing and evaluation of several sensors at multiple sites. One of the challenges of calculating seismic bearing is an adequate signal to noise ratio. The sensor signal to noise ratio is a function of sensor coupling to the ground, seismic propagation and range to target. The goals of testing at multiple sites are to gain a good understanding of the maximum and minimum ranges for bearing and detection and to exploit that information to tailor sensor system emplacement to achieve desired performance. Test sites include 10A Site Devens, MA, McKenna Airfield Ft. Benning, GA and Yuma Proving Ground Yuma, AZ. Geophone sensors evaluated include a 28 Hz triax spike, a 15 Hz triax spike and a hybrid triax spike consisting of a 10 Hz vertical geophone and two 28 Hz horizontal geophones. The algorithm uses raw seismic data to calculate the bearings. All evaluated sensors have triaxial geophone configuration mounted to a spike housing/fixture. The suite of sensors also compares various types of geophones to evaluate benefits in lower bandwidth. The data products of these tests include raw geophone signals, seismic features, seismic bearings, seismic detection and GPS position truth data. The analyses produce Probability of Detection vs range, bearing accuracy vs range, and seismic feature level vs range. These analysis products are compared across test sites and sensor types.

  13. Seismic imaging a carbonate reservoir: The Paris Basin Dogger

    SciTech Connect

    Mougenot, D.

    1995-08-01

    Within the Dogger project, seven partners joined forces (CGG, DHYCA, EAP, ESSO-REP, IFP, TOTAL, TRITON France) to develop an appropriate seismic acquisition, processing and interpretation methodology in order to improve the description of the main oil reservoir (30 m) lying at the top of the Dogger carbonates in the Paris Basin, at a depth of 1900 m. High-resolution 2D Vibroseismic is used to record high frequencies (up to 100 Hz) at the level of the target, and provides sufficiently adequate vertical resolution for the reflections at the top and at the base of the reservoir not to interfere. The upper frequency content of the 3D seismic (70 Hz) is more difficult to enhance. Yet the essential contribution made by the 3D is to evidence, via horizon attributes, sub-meridian lineaments corresponding to faults with throw of several meters which is too weak to be detected on vertical sections. The distribution of these faults, via which water tends to invade the reservoir, and the organization of the amplitudes at the top reservoir reflector, which seems to suggest lateral variations in porosity, are a valuable guide for setting up wells. Three-component seismic (2D-3c) and S-wave emissions did not produce any reflections beyond 30 Hz at the level of the target which is a poor reflector (PS & SS). Only borehole seismic (VSP, offset VSP), where high frequencies are much less attenuated than with surface seismic, provides detailed imaging of the reservoir in converted mode (up to 110 Hz in PP and in PS). The combination of a continuous spatial sampling, such as that obtained in 3D, and of a Vibroseis emission adapted to frequency attenuation, such as that used in 2D, can supply useful information about the thin and discontinuous Dogger reservoir which cannot he provided by mere correlation of the borehole data.

  14. Downhole seismic logging for high-resolution reflection surveying in unconsolidated overburden

    SciTech Connect

    Hunter, J.A.; Pullan, S.E.; Burns, R.A.; Good, R.L.; Harris, J.B.; Pugin, A.; Skvortsov, A.; Goriainov, N.N.

    1998-07-01

    Downhole seismic velocity logging techniques have been developed and applied in support of high-resolution reflection seismic surveys. Data obtained from downhole seismic logging can provide accurate velocity-depth functions and directly correlate seismic reflections to depth. The methodologies described in this paper are designed for slimhole applications in plastic-cased boreholes (minimum ID of 50 mm) and with source and detector arrays that yield similar frequency ranges and vertical depth resolutions as the surface reflection surveys. Compressional- (P-) wave logging uses a multichannel hydrophone array with 0.5-m detector spacings in a fluid-filled borehole and a high-frequency, in-hole shotgun source at the surface. Overlapping array positions downhole results in redundant first-arrival data which can be processed to provide accurate interval velocities. The data also can be displayed as a record suite, showing reflections and directly correlating reflection events with depths. Example applications include identification of gas zones, lithological boundaries within unconsolidated sediments, and the overburden-bedrock interface. Shear- (S-) wave logging uses a slimhole, well-locked, three-component (3-C) geophone pod and a horizontally polarized, hammer-and-loaded-plate source at ground surface. In unconsolidated sediments, shear-wave velocity contrasts can be associated with changes in material density or dynamic shear modulus, which in turn can be related to consolidation. Example applications include identification of a lithological boundary for earthquake hazard applications and mapping massive ice within permafrost materials.

  15. CVD growth and properties of boron phosphide on 3C-SiC

    NASA Astrophysics Data System (ADS)

    Padavala, Balabalaji; Frye, C. D.; Wang, Xuejing; Raghothamachar, Balaji; Edgar, J. H.

    2016-09-01

    Improving the crystalline quality of boron phosphide (BP) is essential for realizing its full potential in semiconductor device applications. In this study, 3C-SiC was tested as a substrate for BP epitaxy. BP films were grown on 3C-SiC(100)/Si, 3C-SiC(111)/Si, and 3C-SiC(111)/4H-SiC(0001) substrates in a horizontal chemical vapor deposition (CVD) system. Films were produced with good crystalline orientation and morphological features in the temperature range of 1000-1200 °C using a PH3+B2H6+H2 mixture. Rotational twinning was absent in the BP due to the crystal symmetry-matching with 3C-SiC. Confocal 3D Raman imaging of BP films revealed primarily uniform peak shift and peak widths across the scanned area, except at defects on the surface. Synchrotron white beam X-ray topography showed the epitaxial relationship between BP and 3C-SiC was (100) < 011 > BP||(100) < 011 > 3C-SiC and (111) < 11 2 ̅ > BP||(111) < 11 2 ̅ > 3C-SiC. Scanning electron microscopy, Raman spectroscopy and X-ray diffraction analysis indicated residual tensile strain in the films and improved crystalline quality at temperatures below 1200 °C. These results indicated that BP properties could be further enhanced by employing high quality bulk 3C-SiC or 3C-SiC epilayers on 4H-SiC substrates.

  16. Tilt and seismicity changes in the Shumagin seismic gap

    SciTech Connect

    Beavan, J.; Hauksson, E.; McNutt, S.R.; Bilham, R.; Jacob, K.H.

    1983-10-21

    Changes in the ground surface tilt and in the rate of seismicity indicate that an aseismic deformation event may have occurred between 1978 and 1980 along the plate boundary in the eastern Aleutians, Alaska, within the Shumagin seismic gap. Pavlof Volcano was unusually quiescent during this period. The proposed event would cause an increase of stress on the shallow locked portion of the plate boundary, bringing it closer to rupture in a great earthquake.

  17. Elastic-Wavefield Seismic Stratigraphy: A New Seismic Imaging Technology

    SciTech Connect

    Bob A. Hardage; Milo M. Backus; Michael V. DeAngelo; Sergey Fomel; Khaled Fouad; Robert J. Graebner; Paul E. Murray; Randy Remington; Diana Sava

    2006-07-31

    The purpose of our research has been to develop and demonstrate a seismic technology that will provide the oil and gas industry a better methodology for understanding reservoir and seal architectures and for improving interpretations of hydrocarbon systems. Our research goal was to expand the valuable science of seismic stratigraphy beyond the constraints of compressional (P-P) seismic data by using all modes (P-P, P-SV, SH-SH, SV-SV, SV-P) of a seismic elastic wavefield to define depositional sequences and facies. Our objective was to demonstrate that one or more modes of an elastic wavefield may image stratal surfaces across some stratigraphic intervals that are not seen by companion wave modes and thus provide different, but equally valid, information regarding depositional sequences and sedimentary facies within that interval. We use the term elastic wavefield stratigraphy to describe the methodology we use to integrate seismic sequences and seismic facies from all modes of an elastic wavefield into a seismic interpretation. We interpreted both onshore and marine multicomponent seismic surveys to select the data examples that we use to document the principles of elastic wavefield stratigraphy. We have also used examples from published papers that illustrate some concepts better than did the multicomponent seismic data that were available for our analysis. In each interpretation study, we used rock physics modeling to explain how and why certain geological conditions caused differences in P and S reflectivities that resulted in P-wave seismic sequences and facies being different from depth-equivalent S-wave sequences and facies across the targets we studied.

  18. Seismic site characterization of an urban dedimentary basin, Livermore Valley, California: Site tesponse, basin-edge-induced surface waves, and 3D simulations

    USGS Publications Warehouse

    Hartzell, Stephen; Leeds, Alena L.; Ramirez-Guzman, Leonardo; Allen, James P.; Schmitt, Robert G.

    2016-01-01

    Thirty‐two accelerometers were deployed in the Livermore Valley, California, for approximately one year to study sedimentary basin effects. Many local and near‐regional earthquakes were recorded, including the 24 August 2014 Mw 6.0 Napa, California, earthquake. The resulting ground‐motion data set is used to quantify the seismic response of the Livermore basin, a major structural depression in the California Coast Range Province bounded by active faults. Site response is calculated by two methods: the reference‐site spectral ratio method and a source‐site spectral inversion method. Longer‐period (≥1  s) amplification factors follow the same general pattern as Bouguer gravity anomaly contours. Site response spectra are inverted for shallow shear‐wave velocity profiles, which are consistent with independent information. Frequency–wavenumber analysis is used to analyze plane‐wave propagation across the Livermore Valley and to identify basin‐edge‐induced surface waves with back azimuths different from the source back azimuth. Finite‐element simulations in a 3D velocity model of the region illustrate the generation of basin‐edge‐induced surface waves and point out strips of elevated ground velocities along the margins of the basin.

  19. Nonlinear seismic response for the 2011 Tohoku earthquake: borehole records versus one-directional three-component propagation models

    NASA Astrophysics Data System (ADS)

    Santisi d'Avila, Maria Paola; Semblat, Jean-François

    2014-04-01

    The seismic response of surficial multilayered soils to strong earthquakes is analysed through a non-linear one-directional three-component (1D-3C) wave propagation model. The three components (3C-polarization) of the incident wave are simultaneously propagated into a horizontal multilayered soil. A 3-D non-linear constitutive relation for dry soils under cyclic loading is implemented in a quadratic line finite element model. The soil rheology is modelled by mean of a multisurface cyclic plasticity model of the Masing-Prandtl-Ishlinskii-Iwan type. Its major advantage is that the rheology is characterized by few non-linear parameters commonly available. Previous studies showed that, when comparing one to 3C unidirectional wave propagation simulations, the soil shear modulus decreases and the dissipation increases, for a given maximum strain amplitude. The 3-D loading path due to the 3C-polarization leads to multiaxial stress interaction that reduces soil strength and increases non-linear effects. Non-linearity and coupling effects between components are more obvious with decreasing seismic velocity ratio in the soil and increasing vertical to horizontal component ratio for the incident wave. This research aims at comparing computed ground motions at the surface of soil profiles in the Tohoku area (Japan) with 3C seismic signals recorded during the 2011 Tohoku earthquake. The 3C recorded downhole motion is imposed as boundary condition at the base of soil layer stack. Notable amplification phenomena are shown, comparing seismograms at the bottom and at the surface. The 1D-3C approach evidences the influence of the 3-D loading path and input wavefield polarization. 3C motion and 3-D stress and strain evolution are evaluated all over the soil profile. The triaxial mechanical coupling is pointed out by observing the variation of the propagating wave polarization all along the duration of seismograms. The variation of the maximum horizontal component of motion with time

  20. Glycine decarboxylase in C3, C4 and C3-C4 intermediate species.

    PubMed

    Schulze, Stefanie; Westhoff, Peter; Gowik, Udo

    2016-06-01

    The glycine decarboxylase complex (GDC) plays a central role in photorespiration. GDC is localized in the mitochondria and together with serine hydroxymethyltransferase it converts two molecules of glycine to one molecule of serine, CO2 and NH3. Overexpression of GDC subunits in the C3 species Arabidopsis thaliana can increase the metabolic flux through the photorespiratory pathway leading to enhanced photosynthetic efficiency and consequently to an enhanced biomass production of the transgenic plants. Changing the spatial expression patterns of GDC subunits was an important step during the evolution of C3-C4 intermediate and likely also C4 plants. Restriction of the GDC activity to the bundle sheath cells led to the establishment of a photorespiratory CO2 pump. PMID:27038285

  1. Seismic Tomography.

    ERIC Educational Resources Information Center

    Anderson, Don L.; Dziewonski, Adam M.

    1984-01-01

    Describes how seismic tomography is used to analyze the waves produced by earthquakes. The information obtained from the procedure can then be used to map the earth's mantle in three dimensions. The resulting maps are then studied to determine such information as the convective flow that propels the crustal plates. (JN)

  2. Seismic Symphonies

    NASA Astrophysics Data System (ADS)

    Strinna, Elisa; Ferrari, Graziano

    2015-04-01

    The project started in 2008 as a sound installation, a collaboration between an artist, a barrel organ builder and a seismologist. The work differs from other attempts of sound transposition of seismic records. In this case seismic frequencies are not converted automatically into the "sound of the earthquake." However, it has been studied a musical translation system that, based on the organ tonal scale, generates a totally unexpected sequence of sounds which is intended to evoke the emotions aroused by the earthquake. The symphonies proposed in the project have somewhat peculiar origins: they in fact come to life from the translation of graphic tracks into a sound track. The graphic tracks in question are made up by copies of seismograms recorded during some earthquakes that have taken place around the world. Seismograms are translated into music by a sculpture-instrument, half a seismograph and half a barrel organ. The organ plays through holes practiced on paper. Adapting the documents to the instrument score, holes have been drilled on the waves' peaks. The organ covers about three tonal scales, starting from heavy and deep sounds it reaches up to high and jarring notes. The translation of the seismic records is based on a criterion that does match the highest sounds to larger amplitudes with lower ones to minors. Translating the seismogram in the organ score, the larger the amplitude of recorded waves, the more the seismogram covers the full tonal scale played by the barrel organ and the notes arouse an intense emotional response in the listener. Elisa Strinna's Seismic Symphonies installation becomes an unprecedented tool for emotional involvement, through which can be revived the memory of the greatest disasters of over a century of seismic history of the Earth. A bridge between art and science. Seismic Symphonies is also a symbolic inversion: the instrument of the organ is most commonly used in churches, and its sounds are derived from the heavens and

  3. On the Y-chromosome haplogroup C3c classification.

    PubMed

    Malyarchuk, Boris A; Derenko, Miroslava; Denisova, Galina

    2012-10-01

    As there are ambiguities in classification of the Y-chromosome haplogroup C3c, relatively frequent in populations of Northern Asia, we analyzed all three haplogroup-defining markers M48, M77 and M86 in C3-M217-individuals from Siberia, Eastern Asia and Eastern Europe. We have found that haplogroup C3c is characterized by the derived state at M48, whereas mutations at both M77 and M86 define subhaplogroup C3c1. The branch defined by M48 alone would belong to subhaplogroup C3c*, characteristic for some populations of Central and Eastern Siberia, such as Koryaks, Evens, Evenks and Yukaghirs. Subhaplogroup C3c* individuals could be considered as remnants of the Neolithic population of Siberia, based on the age of C3c*-short tandem repeat variation amounting to 4.5 ± 2.4 thousand years. PMID:22810113

  4. Poliovirus protease 3C(pro) kills cells by apoptosis.

    PubMed

    Barco, A; Feduchi, E; Carrasco, L

    2000-01-20

    The tetracycline-based Tet-Off expression system has been used to analyze the effects of poliovirus protease 3C(pro) on human cells. Stable HeLa cell clones that express this poliovirus protease under the control of an inducible, tightly regulated promoter were obtained. Tetracycline removal induces synthesis of 3C protease, followed by drastic morphological alterations and cellular death. Degradation of cellular DNA in nucleosomes and generation of apoptotic bodies are observed from the second day after 3C(pro) induction. The cleavage of poly(ADP-ribose) polymerase, an enzyme involved in DNA repair, occurs after induction of 3C(pro), indicating caspase activation by this poliovirus protease. The 3C(pro)-induced apoptosis is blocked by the caspase inhibitor z-VAD-fmk. Our findings suggest that the protease 3C is responsible for triggering apoptosis in poliovirus-infected cells by a mechanism that involves caspase activation.

  5. Compressional wave character in gassy, near-surface sediments in southern Louisiana determined from variable frequency cross-well, borehole logging, and surface seismic measurements

    SciTech Connect

    Thompson, M.D.; McGinnis, L.D.; Wilkey, P.L.; Fasnacht, T.

    1995-06-01

    Velocity and attenuation data were used to test theoretical equations describing the frequency dependence of compressional wave velocity and attenuation through gas-rich sediments in coastal Louisiana. The cross-well data were augmented with velocities derived from a nearby seismic refraction station using a low-frequency source. Energy at 1 and 3 kHz was successfully transmitted over distances from 3.69 to 30 m; the 5 and 7-kHz data were obtained only at distances up to 20 m. Velocity tomograms were constructed for one borehole pair and covered a depth interval of 10--50 m. Results from the tomographic modeling indicate that gas-induced low velocities are present to depths of greater than 40 m. Analysis of the velocity dispersion suggests that gas-bubble resonance must be greater than 7 kHz, which is above the range of frequencies used in the experiment. Washout of the boreholes at depths above 15 m resulted in a degassed zone containing velocities higher than those indicated in both nearby refraction and reflection surveys. Velocity and attenuation information were obtained for a low-velocity zone centered at a depth of approximately 18 m. Measured attenuations of 1.57, 2.95, and 3.24 dB/m for the 3-, 5-, and 7-kHz signals, respectively, were modeled along with the velocity data using a silt-clay sediment type. Density and porosity data for the model were obtained from the geophysical logs; the bulk and shear moduli were estimated from published relationships. Modeling results indicate that gas bubbles measuring 1 mm in diameter occupy at least 25% to 35% of the pore space.

  6. Joint Inversion of Body-Wave Arrival Times and Surface-Wave Dispersion Data for Three-Dimensional Seismic Velocity Structure Around SAFOD

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Thurber, C. H.; Maceira, M.; Roux, P.

    2013-12-01

    The crust around the San Andreas Fault Observatory at depth (SAFOD) has been the subject of many geophysical studies aimed at characterizing in detail the fault zone structure and elucidating the lithologies and physical properties of the surrounding rocks. Seismic methods in particular have revealed the complex two-dimensional (2D) and three-dimensional (3D) structure of the crustal volume around SAFOD and the strong velocity reduction in the fault damage zone. In this study we conduct a joint inversion using body-wave arrival times and surface-wave dispersion data to image the P-and S-wave velocity structure of the upper crust surrounding SAFOD. The two data types have complementary strengths - the body-wave data have good resolution at depth, albeit only where there are crossing rays between sources and receivers, whereas the surface waves have very good near-surface resolution and are not dependent on the earthquake source distribution because they are derived from ambient noise. The body-wave data are from local earthquakes and explosions, comprising the dataset analyzed by Zhang et al. (2009). The surface-wave data are for Love waves from ambient noise correlations, and are from Roux et al. (2011). The joint inversion code is based on the regional-scale version of the double-difference (DD) tomography algorithm tomoDD. The surface-wave inversion code that is integrated into the joint inversion algorithm is from Maceira and Ammon (2009). The propagator matrix solver in the algorithm DISPER80 (Saito, 1988) is used for the forward calculation of dispersion curves from layered velocity models. We examined how the structural models vary as we vary the relative weighting of the fit to the two data sets and in comparison to the previous separate inversion results. The joint inversion with the 'optimal' weighting shows more clearly the U-shaped local structure from the Buzzard Canyon Fault on the west side of SAF to the Gold Hill Fault on the east side.

  7. Seismic surface-wave dispersion profiling versus shear-wave refraction tomography on a granite-micaschists contact at Plœmeur hydrological observatory (France)

    NASA Astrophysics Data System (ADS)

    Pasquet, S.; Bodet, L.; Dhemaied, A.; Guérin, R.; Longuevergne, L.; Faycal, R.

    2013-12-01

    Despite well-known generation and detection issues, shear (S-) wave-related techniques grow in popularity with the increase of multicomponent data acquisitions in hydrocarbon exploration. In the meantime, recent studies demonstrated that pressure (P-) wave reflection, P-wave refraction and surface-wave dispersion data could be simultaneously acquired and analyzed for the characterization of the investigated medium. Retrieving 2D P-wave velocity (Vp) and S-wave velocity (Vs) sections with a single standard acquisition setup appears promising and attractive in terms of time and equipment costs, more particularly in the context of near-surface applications (at depth lower than 100 m). The literature even shows recent attempts of using Vp/Vs ratio to estimate hydrological parameters of aquifer systems. But refraction tomography and surface-wave dispersion inversion obviously involve distinct characteristics of the wavefield and different assumptions about the medium. The methods consequently provide results of different resolutions and investigation depths. We addressed these issues thanks to a seismic survey conducted on a well-known granite-micaschists contact at Plœmeur hydrological observatory (France). We performed simultaneous P-wave refraction tomography and surface-wave profiling, along with SH-wave refraction tomography, on a line intersecting the contact zone. The combined interpretation of Vp and Vs sections retrieved from refraction tomography helps defining the lateral extent of the contact zone, when only one section is insufficient. As for surface-wave profiling, we used offset moving windows and dispersion stacking techniques to extract a collection of local dispersion measurements along the line. We then inverted each dispersion curve separately and reconstructed a pseudo-2D Vs section along the profile. Three different window sizes were tested. They provide sections evidently different in terms of lateral resolution and investigation depth. To select

  8. Seismic sensitivity to sub-surface solar activity from 18 yr of GOLF/SoHO observations

    NASA Astrophysics Data System (ADS)

    Salabert, D.; García, R. A.; Turck-Chièze, S.

    2015-06-01

    Solar activity has significantly changed over the last two Schwabe cycles. After a long and deep minimum at the end of Cycle 23, the weaker activity of Cycle 24 contrasts with the previous cycles. In this work, the response of the solar acoustic oscillations to solar activity is used in order to provide insights into the structural and magnetic changes in the sub-surface layers of the Sun during this on-going unusual period of low activity. We analyze 18 yr of continuous observations of the solar acoustic oscillations collected by the Sun-as-a-star GOLF instrument on board the SoHO spacecraft. From the fitted mode frequencies, the temporal variability of the frequency shifts of the radial, dipolar, and quadrupolar modes are studied for different frequency ranges that are sensitive to different layers in the solar sub-surface interior. The low-frequency modes show nearly unchanged frequency shifts between Cycles 23 and 24, with a time evolving signature of the quasi-biennial oscillation, which is particularly visible for the quadrupole component revealing the presence of a complex magnetic structure. The modes at higher frequencies show frequency shifts that are 30% smaller during Cycle 24, which is in agreement with the decrease observed in the surface activity between Cycles 23 and 24. The analysis of 18 yr of GOLF oscillations indicates that the structural and magnetic changes responsible for the frequency shifts remained comparable between Cycle 23 and Cycle 24 in the deeper sub-surface layers below 1400 km as revealed by the low-frequency modes. The frequency shifts of the higher-frequency modes, sensitive to shallower regions, show that Cycle 24 is magnetically weaker in the upper layers of Sun. Appendices are available in electronic form at http://www.aanda.orgThe following 68 GOLF frequency tables are available and Table A.1 is also available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc

  9. Results of the application of seismic-reflection and electromagnetic techniques for near-surface hydrogeologic and environmental investigations at Fort Bragg, North Carolina

    USGS Publications Warehouse

    Meyer, M.T.; Fine, J.M.

    1997-01-01

    As part of the U.S. Geological Survey's Resource Conservation and Recovery Act, Facilities Investigations at Fort Bragg, North Carolina, selected geophysical techniques were evaluated for their usefulness as assessment tools for determining subsurface geology, delineating the areal extent of potentially contaminated landfill sites, and locating buried objects and debris of potential environmental concern. Two shallow seismic-reflection techniques (compression and shear wave) and two electromagnetic techniques (ground-penetrating radar and terrain conductivity) were evaluated at several sites at the U.S. Army Base. The electromagnetic techniques also were tested for tolerance to cultural noise, such as nearby fences, vehicles, and power lines. For the terrain conductivity tests, two instruments were used--the EM31 and EM34, which have variable depths of exploration. The shallowest reflection event was 70 feet below land surface observed in common-depth point, stacked compression-wave data from 24- and 12-fold shallow-seismic-reflection surveys. Several reflection events consistent with clay-sand interfaces between 70 and 120 feet below land surface, along with basement-saprolite surfaces, were imaged in the 24-fold, common- depth-point stacked data. 12-fold, common-depth-point stacked data set contained considerably more noise than the 24-fold, common-depth-point data, due to reduced shot-to-receiver redundancy. Coherent stacked reflection events were not observed in the 24-fold, common-depth-point stacked shear-wave data because of the partial decoupling of the shear- wave generator from the ground. At one site, ground-penetrating radar effectively delineated a shallow, 2- to 5-foot thick sand unit bounded by thin (less than 1 foot) clay layers. The radar signal was completely attenuated where the overlying and underlying clay units thickened and the sand unit thinned. The pene- tration depth of the radar signal was less than 10 feet below land surface. A slight

  10. Benchmarking Passive Seismic Methods of Imaging Surface Wave Velocity Interfaces Down to 300 m — Mapping Murray Basin Thickness in Southeastern Australia

    NASA Astrophysics Data System (ADS)

    Gorbatov, A.; Czarnota, K.

    2015-12-01

    In shallow passive seismology it is generally thought that the spatial autocorrelation (SPAC) method is more robust than the horizontal over vertical spectral ratio (HVSR) method at resolving the depth to surface-wave velocity (Vs) interfaces. Here we present results of a field test of these two methods over ten drill sites in Victoria, Australia. The target interface is the base of Cenozoic unconsolidated to semi-consolidated clastic and/or carbonate sediments of the Murray Basin, which overlie Paleozoic crystalline rocks. Drilled depths of this interface are between 27 and 300 m. A three-arm spiral array, with a radius of 250 m, consisting of 13 Trillium compact broadband seismometers was deployed at each site for 7-21 hours. The Vs architecture beneath each site was determined through nonlinear inversion of HVSR and SPAC data using the neighborhood algorithm of Sambridge (1999) implemented in geopsy by Wathelet et al (2005). The HVSR technique yielded depth estimates, of the target interface (Vs > 1000 m/s), generally within 20% error. Successful estimates were even obtained at a site with an inverted velocity profile, where Quaternary basalts overlie Neogene sediments. Half of the SPAC estimates showed significantly higher errors than obtained using HVSR. Joint inversion provided the most reliable estimates but was unstable at three sites. We attribute the surprising success of HVSR over SPAC to a low content of transient signals within the seismic record caused by low degrees of anthropogenic noise at the benchmark sites. At a few sites SPAC curves showed clear overtones suggesting that more reliable SPAC estimates maybe obtained utilizing a multi modal inversion. Nevertheless, our study seems to indicate that reliable basin thickness estimates in remote Australia can be obtained utilizing HVSR data from a single seismometer, without a priori knowledge of the surface-wave velocity of the basin material, thereby negating the need to deploy cumbersome arrays.

  11. Exploring Critical Assumptions of Petrophysical Models in Fractured Aquifers by Comparing Estimated Porosity Values Obtained from Surface Nuclear Magnetic Resonance and Shallow Seismic Refraction Surveys.

    NASA Astrophysics Data System (ADS)

    Flinchum, B. A.; Holbrook, W. S.; Grana, D.; Parsekian, A.

    2015-12-01

    Estimating subsurface porosity from most near-surface geophysical techniques relies on petrophysical relationships. Using petrophysical relationships are challenging because they require many assumptions and oftentimes require site-specific constants. Despite complexities and challenges, the petrophysical relationships are critical to convert the measurable physical properties into hydrologic properties such as porosity, water content and ultimately hydraulic conductivity. In this study we compare porosities derived from shallow seismic refraction (SSR) and surface nuclear magnetic resonance (SNMR) in a fractured granite aquifer in the Laramie Range, Wyoming. To estimate porosity from the SSR data we use a Bayesian inversion based on Hertz-Mindlin contact theory and Hashin- Strickman boundaries. This type of petrophysical model requires us to make assumptions about the grain structure, mineralogy and water content. Using water table measurements from a borehole we assume that all pores are fully saturated below 10 meters, thus the SNMR measurement provides an estimate of porosity. If the petrophysical model and the assumptions that are required to use it were correct and the SNMR measurements were perfect, the estimates of porosities derived from two distinct physical measurements should provide the same porosity. Interestingly, we observe a large discrepancy in the porosities derived from this unique combination of measurements. At depths of 10 to 20 meters, the area that we interpret as fractured bedrock and where the assumption of fully saturated pores holds, the SSR predicted porosities are 15 to 20 % higher than those predicted by SNMR. Previous comparisons of the Bayesian inversion have shown it does well to predict porosity within the saprolite. The large discrepancy illustrates the need to use separate petrophysical models in the weathered and fractured zones of granite aquifers. More research is needed to figure out how to combine different petrophysical

  12. Atomic probe microscopy of 3C SiC films grown on 6H SiC substrates

    NASA Technical Reports Server (NTRS)

    Steckl, A. J.; Roth, M. D.; Powell, J. A.; Larkin, D. J.

    1993-01-01

    The surface of 3C SiC films grown on 6H SiC substrates has been studied by atomic probe microscopy in air. Atomic-scale images of the 3C SiC surface have been obtained by STM which confirm the 111 line type orientation of the cubic 3C layer grown on the 0001 plane type surface of the hexagonal 6H substrate. The nearest-neighbor atomic spacing for the 3C layer has been measured to be 3.29 +/- 0.2 A, which is within 7 percent of the bulk value. Shallow terraces in the 3C layer have been observed by STM to separate regions of very smooth growth in the vicinity of the 3C nucleation point from considerably rougher 3C surface regions. These terraces are oriented at right angles to the growth direction. Atomic force microscopy has been used to study etch pits present on the 6H substrate due to high temperature HCl cleaning prior to CVD growth of the 3C layer. The etch pits have hexagonal symmetry and vary in depth from 50 nm to 1 micron.

  13. Structural Geology of the Northwestern Portion of Los Alamos National Laboratory, Rio Grande Rift, New Mexico: Implications for Seismic Surface Rupture Potential from TA-3 to TA-55

    SciTech Connect

    Jamie N. Gardner: Alexis Lavine; Giday WoldeGabriel; Donathon Krier; David Vaniman; Florie Caporuscio; Claudia Lewis; Peggy Reneau; Emily Kluk; M. J. Snow

    1999-03-01

    Los Alamos National Laboratory lies at the western boundary of the Rio Grande rift, a major tectonic feature of the North American Continent. Three major faults locally constitute the modem rift boundary, and each of these is potentially seismogenic. In this study we have gathered structural geologic data for the northwestern portion of Los Alamos National Laboratory through high-precision geologic mapping, conventional geologic mapping, stratigraphic studies, drilling, petrologic studies, and stereographic aerial photograph analyses. Our study area encompasses TA-55 and TA-3, where potential for seismic surface rupture is of interest, and is bounded on the north and south by the townsite of Los Alamos and Twomile Canyon, respectively. The study area includes parts of two of the potentially active rift boundary faults--the Pajarito and Rendija Canyon faults-that form a large graben that we name the Diamond Drive graben. The graben embraces the western part of the townsite of Los Alamos, and its southern end is in the TA-3 area where it is defined by east-southeast-trending cross faults. The cross faults are small, but they accommodate interactions between the two major fault zones and gentle tilting of structural blocks to the north into the graben. North of Los Alamos townsite, the Rendija Canyon fault is a large normal fault with about 120 feet of down-to-the-west displacement over the last 1.22 million years. South from Los Alamos townsite, the Rendija Canyon fault splays to the southwest into a broad zone of deformation. The zone of deformation is about 2,000 feet wide where it crosses Los Alamos Canyon and cuts through the Los Alamos County Landfill. Farther southwest, the fault zone is about 3,000 feet wide at the southeastern corner of TA-3 in upper Mortandad Canyon and about 5,000 feet wide in Twomile Canyon. Net down-to-the-west displacement across the entire fault zone over the last 1.22 million years decreases to the south as the fault zone broadens as

  14. Surface deformation and seismic signatures associated with the eruption cycle of Lone Star Geyser, Yellowstone National Park

    NASA Astrophysics Data System (ADS)

    Gomez, F. G.; Johnson, H. E., III; LeWinter, A. L.; Finnegan, D. C.; Sandvol, E. A.; Nayak, A.; Hurwitz, S.

    2014-12-01

    Geysers are important subjects for studying processes involved with multi-phase eruptions. As part of a larger field effort, this study applies imaging geodesy and seismology to study eruptive cycles of the Lone Star Geyser in Yellowstone National Park. Lone Star Geyser is an ideal candidate for such study, as it erupts with a nearly regular period of approximately 3 hours. The geyser includes a 5 m diameter cone that rises 2 meters above the sinter terrace, and the entire system can be viewed from a nearby hillside. Fieldwork was accomplished during April 2014. Ground-based interferometric radar (GBIR) and terrestrial laser scanning (TLS) were used to image possible surface deformations associated with Lone Star Geyer's eruption cycles. Additional observations were provided by global positioning system (GPS) measurements and six broad-band seismometers deployed in the immediate vicinity of the geyser. The GBIR and TLS were deployed approximately 65 meters from the sinter cone of the geyser. The GBIR involves a ku-band radar (1.7 cm wavelength) that is sensitive to approximately half-millimeter changes in the line-of-sight distance. Radar images were acquired every minute for 3 or more eruptions per day. Temporally redundant, overlapping interferograms were used to improve the sensitivity and interpolate a minute-wise time series of line-of-sight displacement, and efforts were made to account for possible path-delay effects resulting from water vapor around the geyser cone. Repeat (every minute) high-speed TLS scans were acquired for multiple eruption cycles over the course of two-days. Resulting measurement point spacing on the sinter cone was ~3cm. The TLS point-clouds were geo-referenced using static surveyed reflectors and scanner positions. In addition to measuring ground deformation, filtering and classification of the TLS point cloud was used to construct a mask that allows radar interferometry to exclude non-ground areas (vegetation, snow, sensors

  15. Yields of Soviet underground nuclear explosions at Novaya Zemlya, 1964-1976, from seismic body and surface waves.

    PubMed

    Sykes, L R; Wiggins, G C

    1986-01-01

    Surface and body wave magnitudes are determined for 15 U.S.S.R. underground nuclear weapons tests conducted at Novaya Zemlya between 1964 and 1976 and are used to estimate yields. These events include the largest underground explosions detonated by the Soviet Union. A histogram of body wave magnitude (m(b)) values indicates a clustering of explosions at a few specific yields. The most pronounced cluster consists of six explosions of yield near 500 kilotons. Several of these seem to be tests of warheads for major strategic systems that became operational in the late 1970s. The largest Soviet underground explosion is estimated to have a yield of 3500 +/- 600 kilotons, somewhat smaller than the yield of the largest U.S. underground test. A preliminary estimation of the significance of tectonic release is made by measuring the amplitude of Love waves. The bias in m(b) for Novaya Zemlya relative to the Nevada test site is about 0.35, nearly identical to that of the eastern Kazakhstan test site relative to Nevada.

  16. Why Are C3-C4 Intermediate Species Rare?

    NASA Astrophysics Data System (ADS)

    Johnson, J. E.; Field, C. B.; Berry, J. A.

    2014-12-01

    While C3-C4 intermediate photosynthesis is thought to represent the evolutionary bridge between C3 and C4 photosynthesis, C3-C4 intermediate species are ecologically rare in comparison to both C3 and C4 species. Here, we report results from a laboratory experiment, field observations, and model simulations that suggest a new explanation for the ecological rarity of C3-C4 intermediate species. In the laboratory experiment, we combined gas exchange and fluorescence to characterize the temperature response of photosynthesis in three closely-related species in the genus Flaveria that are representatives of the C3, C3-C4 intermediate, and C4 photosynthetic pathways. The leaf temperature that maximized the quantum yield for CO2 assimilation (Topt(ΦCO2)) was 24.9 ± 0.7°C in Flaveria robusta (C3), 29.8 ± 1.0°C in F. chloraefolia (C3-C4), and 35.7 ± 0.8°C in F. bidentis (C4), and was linearly related to the temperature sensitivity of the coupling between CO2 assimilation and electron transport (d(ΦCO2/ ΦPSII)/dT)). While F. chloraefolia does not simultaneously occur with F. robusta and F. bidentis in naturally-assembled communities, this C3-C4 intermediate species does occur with other C3 and C4 species. During the growing season in two of these mixed-photosynthetic-type communities, leaf temperatures for F. chloraefolia were similar to the Topt(ΦCO2) determined in the laboratory. A model of maximum potential carbon gain suggests that competitive coexistence of C3, C3-C4 intermediate, and C4 species could be dependent on a temperature regime that highlights the distinct relative advantages of the C3-C4 intermediate pathway. In combination, these results suggest that the relative temperature sensitivity of the C3, C3-C4 intermediate, and C4 photosynthetic pathways combined with environmental variation in temperature may help to explain why C3-C4 intermediate species are generally rare.

  17. Three-dimensional passive imaging of complex seismic fault systems: evidence of surface traces of the Issyk-Ata fault (Kyrgyzstan)

    NASA Astrophysics Data System (ADS)

    Pilz, Marco; Parolai, Stefano; Bindi, Dino

    2013-09-01

    Nowadays, an increasing number of seismological imaging studies are published taking advantage of the increasing popularity of analysing empirical Green's functions obtained from high-frequency ambient seismic noise. However, especially on a local scale results could potentially be biased in regions where topography is not small compared to the wavelength and the penetration depth of the considered waves. Current 2-D seismic techniques are often inadequate when solving such 3-D geophysical problems, which include the complication of seismic imaging for cases where there are pronounced relief effects. For example, information about the geologic subsurface structure and deformational patterns is necessary for accurate site characterization and seismic hazard assessment. Here we show that an ad hoc passive seismic tomography approach can identify and describe complex 3-D structures, which can help to accurately and efficiently map the shear-wave velocities of the surficial soil layers, even in cases of significant topography relief. We test our technique by using simulations of seismic noise for a simple realistic site and show for a real data set across the Issyk-Ata fault, Kyrgyzstan, which is located at southern border of the capital, Bishkek, this novel approach has identified two different small fault branches and a clear shear-wave velocity contrast across the fault.

  18. Infrasound Generation from the HH Seismic Hammer.

    SciTech Connect

    Jones, Kyle Richard

    2014-10-01

    The HH Seismic hammer is a large, "weight-drop" source for active source seismic experiments. This system provides a repetitive source that can be stacked for subsurface imaging and exploration studies. Although the seismic hammer was designed for seismological studies it was surmised that it might produce energy in the infrasonic frequency range due to the ground motion generated by the 13 metric ton drop mass. This study demonstrates that the seismic hammer generates a consistent acoustic source that could be used for in-situ sensor characterization, array evaluation and surface-air coupling studies for source characterization.

  19. Multichannel analysis of surface-waves and integration of downhole acoustic televiewer imaging, ultrasonic Vs and Vp, and vertical seismic profiling in an NEHRP-standard classification, South of Concordia, Kansas, USA

    NASA Astrophysics Data System (ADS)

    Raef, Abdelmoneam; Gad, Sabreen; Tucker-Kulesza, Stacey

    2015-10-01

    Seismic site characteristics, as pertaining to earthquake hazard reduction, are a function of the subsurface elastic moduli and the geologic structures. This study explores how multiscale (surface, downhole, and laboratory) datasets can be utilized to improve "constrained" average Vs30 (shear-wave velocity to a 30-meter depth). We integrate borehole, surface and laboratory measurements for a seismic site classification based on the standards of the National Earthquake Hazard Reduction Program (NEHRP). The seismic shear-wave velocity (Vs30) was derived from a geophysical inversion workflow that utilized multichannel analysis of surface-waves (MASW) and downhole acoustic televiewer imaging (DATI). P-wave and S-wave velocities, based on laboratory measurements of arrival times of ultrasonic-frequency signals, supported the workflow by enabling us to calculate Poisson's ratio, which was incorporated in building an initial model for the geophysical inversion of MASW. Extraction of core samples from two boreholes provided lithology and thickness calibration of the amplitudes of the acoustic televiewer imaging for each layer. The MASW inversion, for calculating Vs sections, was constrained with both ultrasonic laboratory measurements (from first arrivals of Vs and Vp waveforms at simulated in situ overburden stress conditions) and the downhole acoustic televiewer (DATV) amplitude logs. The Vs30 calculations enabled categorizing the studied site as NEHRP-class "C" - very dense soil and soft rock. Unlike shallow fractured carbonates in the studied area, S-wave and P-wave velocities at ultrasonic frequency for the deeper intact shale core-samples from two boreholes were in better agreement with the corresponding velocities from both a zero-offset vertical seismic profiling (VSP) and inversion of Rayleigh-wave velocity dispersion curves.

  20. Very High Resolution Optical Images for Detecting Co-seismic Surface Effects: the Cases of the 2005 Kashmir (Pakistan) and the 2003 Bam (Iran) Earthquakes

    NASA Astrophysics Data System (ADS)

    Chini, M.; Cinti, F. R.; Stramondo, S.

    2008-12-01

    Very High Resolution (VHR) satellite panchromatic image has revealed to be a reliable tool to detect surface effects of natural disasters. This is particularly true whereas the hit territory is a remote land and/or with logistic and security problems. Data from this kind of sensor have a potential for more exhaustive and accurate mapping of the environment with details of sub-meter ground resolution. We show two large earthquake case studies, the 2005 Mw 7.6 Kashmir and the 2003 Mw 6.6 Bam events, both producing significant surface effects as ruptures, landslides and building damages. In order to test the capability of VHR images to recognize and evaluate such features we used panchromatic QuickBird imagery (0.6 m spatial resolution) acquired before and after the events (kindly provided by DigitalGlobe). Concerning the Pakistan we focus on the Muzaffarabad and Balakot areas, both crossed by the earthquake fault and experiencing edifice collapses. Same sort of analysis is performed for the ancient town of Bam. We proceed with: 1. identification on the images of the main rupture trace and of major landslides; 2. generation of a detailed spatial distribution of damage and collapses through a single building automatic classification approach; 3. cross-comparison of the different surface effects. The QuickBird panchromatic images provide a view of the co-seismic features at large scale, revealing complex geometric pattern of the cracks and compressional deformation features. It is possible to detect the lateral sense of movement, and based on the sun shade projection in the images, we infer the facing of the scarp, thus the uplifted side. Regarding point two, if in one hand the use of QuickBird images leads to detect very small details, on the other hand buildings become rather complex structures. Furthermore they may be surrounded by scattering objects making less evident the contrast between the roofs and the ground, thus increasing the difficulties in the

  1. Co-seismic secondary surface fractures on southeastward extension of the rupture zone of the 2005 Kashmir earthquake

    NASA Astrophysics Data System (ADS)

    Jayangondaperumal, R.; Thakur, V. C.

    2008-01-01

    After the 2005 Kashmir earthquake, we mapped surface ground fractures in Tangdhar, Uri, Rajouri and Punch sectors and liquefaction features in Jammu area lying close to the eastern side of the Line of Control (LOC) in Kashmir, India. The NW trending ground fractures occurred largely in the hanging wall zone of the southeastern extension of the causative fault in Tangdhar and Uri sectors. The principal compressive stress deduced from the earthquake induced ground fractures is oriented at N10°, whereas the causative Balakot-Bagh fault strikes 330°. The fault-plane solution indicates primarily SW thrusting of the causative fault with a component of strike-slip motion. The ground fractures reflect pronounced strike-slip together with some tensile component. The Tangdhar area showing left-lateral strike-slip motion lies on the hanging wall, and the Uri region showing right-lateral strike-slip movement is located towards the southeastern extension of the causative fault zone. The shear fractures are related to static stress that was responsible for the failure of causative fault. The tensile fractures with offsets are attributed to combination of both static and dynamic stresses, and the fractures and openings without offsets owe their origin due to dynamic stress. In Punch-Rajouri and Jammu area, which lies on the footwall, the fractures and liquefactions were generated by dynamic stress. The occurrence of liquefaction features in the out board part of the Himalayan range front near Jammu is suggestive of stress transfer ˜ 230 km southeast of the epicenter. The Balakot-Bagh Fault (BBF), the Muzaffarabad anticline, the rupture zone of causative fault and the zone of aftershocks — all are aligned in a ˜ 25 km wide belt along the NW-SE trending regional Himalayan strike of Kashmir region and lying between the MBT and the Riasi Thrust (Murree Thrust), suggesting a seismogenic zone that may propagate towards the southeast to trigger an earthquake in the eastern part of

  2. Seismic Imager Space Telescope

    NASA Technical Reports Server (NTRS)

    Sidick, Erkin; Coste, Keith; Cunningham, J.; Sievers,Michael W.; Agnes, Gregory S.; Polanco, Otto R.; Green, Joseph J.; Cameron, Bruce A.; Redding, David C.; Avouac, Jean Philippe; Ampuero, Jean Paul; Leprince, Sebastien; Michel, Remi

    2012-01-01

    A concept has been developed for a geostationary seismic imager (GSI), a space telescope in geostationary orbit above the Pacific coast of the Americas that would provide movies of many large earthquakes occurring in the area from Southern Chile to Southern Alaska. The GSI movies would cover a field of view as long as 300 km, at a spatial resolution of 3 to 15 m and a temporal resolution of 1 to 2 Hz, which is sufficient for accurate measurement of surface displacements and photometric changes induced by seismic waves. Computer processing of the movie images would exploit these dynamic changes to accurately measure the rapidly evolving surface waves and surface ruptures as they happen. These measurements would provide key information to advance the understanding of the mechanisms governing earthquake ruptures, and the propagation and arrest of damaging seismic waves. GSI operational strategy is to react to earthquakes detected by ground seismometers, slewing the satellite to point at the epicenters of earthquakes above a certain magnitude. Some of these earthquakes will be foreshocks of larger earthquakes; these will be observed, as the spacecraft would have been pointed in the right direction. This strategy was tested against the historical record for the Pacific coast of the Americas, from 1973 until the present. Based on the seismicity recorded during this time period, a GSI mission with a lifetime of 10 years could have been in position to observe at least 13 (22 on average) earthquakes of magnitude larger than 6, and at least one (2 on average) earthquake of magnitude larger than 7. A GSI would provide data unprecedented in its extent and temporal and spatial resolution. It would provide this data for some of the world's most seismically active regions, and do so better and at a lower cost than could be done with ground-based instrumentation. A GSI would revolutionize the understanding of earthquake dynamics, perhaps leading ultimately to effective warning

  3. Surface seismic refraction/reflection measurement determinations of potential site resonances and the areal uniformity of NEHRP site class D in Memphis, Tennessee

    USGS Publications Warehouse

    Williams, R.A.; Wood, S.; Stephenson, W.J.; Odum, J.K.; Meremonte, M.E.; Street, R.; Worley, D.M.

    2003-01-01

    We determined S-wave velocities (Vs) to about 40-m depth at 65 locations in the Memphis-Shelby County, Tennessee, area. The Vs measurements were made using high-resolution seismic refraction and reflection methods on the ground surface. We find a clear difference in the Vs profiles between sites located on the Mississippi River flood plain and those located to the east, mostly covered by loess, in the urban areas of Memphis. The average Vs to 30-m depth at 19 sites on the modern Mississippi River floodplain averages 197 m/s (?? 15 m/s) and places 17 of these sites at the low end of NEHRP soil profile category type D (average Vs 180-360 m/s). The two remaining sites are type E. Vs to 30-m depth at 46 sites in the urban areas east of the modern floodplain are more variable and generally higher than the floodplain sites, averaging about 262 m/s (??45 m/s), still within category D. We often observed the base of the loess as a prominent S-wave reflection and as an increase in Vs to about 500 m/s. Based on the two-way travel time of this reflection, during an earthquake the impedance boundary at the loess base may generate resonances in the 3- to 6-Hz range over many areas of Memphis. Amplitude spectra from four local earthquakes recorded at one site located on loess indicate consistent resonance peaks in the 4.5- to 6.5-Hz range.

  4. Seismic moulin tremor

    NASA Astrophysics Data System (ADS)

    Roeoesli, Claudia; Walter, Fabian; Ampuero, Jean-Paul; Kissling, Edi

    2016-08-01

    Through glacial moulins, meltwater is routed from the glacier surface to its base. Moulins are a main feature feeding subglacial drainage systems and thus influencing basal motion and ice dynamics, but their geometry remains poorly known. Here we show that analysis of the seismic wavefield generated by water falling into a moulin can help constrain its geometry. We present modeling results of hour-long seimic tremors emitted from a vertical moulin shaft, observed with a seismometer array installed at the surface of the Greenland Ice Sheet. The tremor was triggered when the moulin water level exceeded a certain height, which we associate with the threshold for the waterfall to hit directly the surface of the moulin water column. The amplitude of the tremor signal changed over each tremor episode, in close relation to the amount of inflowing water. The tremor spectrum features multiple prominent peaks, whose characteristic frequencies are distributed like the resonant modes of a semiopen organ pipe and were found to depend on the moulin water level, consistent with a source composed of resonant tube waves (water pressure waves coupled to elastic deformation of the moulin walls) along the water-filled moulin pipe. Analysis of surface particle motions lends further support to this interpretation. The seismic wavefield was modeled as a superposition of sustained wave radiation by pressure sources on the side walls and at the bottom of the moulin. The former was found to dominate the wave field at close distance and the latter at large distance to the moulin.

  5. USING RECENT ADVANCES IN 2D SEISMIC TECHNOLOGY AND SURFACE GEOCHEMISTRY TO ECONOMICALLY REDEVELOP A SHALLOW SHELF CARBONATE RESERVOIR: VERNON FIELD, ISABELLA COUNTY, MI

    SciTech Connect

    James R. Wood; A. Wylie; W. Quinlan

    2004-04-01

    One of the main objectives of this demonstration project is to test surface geochemical techniques for detecting trace amounts of light hydrocarbons in pore gases as a means of reducing risk in hydrocarbon exploration and production. As part of the project, several field demonstrations were undertaken to assess the validity and usefulness of the microbial surface geochemical technique. The important observations from each of these field demonstrations are briefly reviewed in this annual report. These demonstrations have been successful in identifying the presence or lack of hydrocarbons in the subsurface and can be summarized as follows: (1) The surface geochemistry data showed a fair-to-good microbial anomaly that may indicate the presence of a fault or stratigraphic facies change across the drilling path of the State Springdale & O'Driscoll No.16-16 horizontal demonstration well in Manistee County, Michigan. The well was put on production in December 2003. To date, the well is flowing nearly 100 barrels of liquid hydrocarbons per day plus gas, which is a good well in Michigan. Reserves have not been established yet. Two successful follow-up horizontal wells have also been drilled in the Springdale area. Additional geochemistry data will be collected in the Springdale area in 2004. (2) The surface geochemistry sampling in the Bear Lake demonstration site in Manistee County, Michigan was updated after the prospect was confirmed and production begun; the original subsurface and seismic interpretation used to guide the location of the geochemical survey for the Charlich Fauble re-entry was different than the interpretation used by the operator who ultimately drilled the well. As expected, the anomaly appears to be diminishing as the positive (apical) microbial anomaly is replaced by a negative (edge) anomaly, probably due to the pressure draw-down in the reservoir. (3) The geochemical sampling program over the Vernon Field, Isabella County, Michigan is now

  6. Towards Large Area Growth of 3C-SiC

    SciTech Connect

    Vasiliauskas, Remigijus; Liljedahl, Rickard; Syvaejaervi, Mikael; Yakimova, Rositza

    2010-11-01

    In this work we have analyzed the possibility of upscaling the growth of 3C-SiC. The growth was done at different temperatures to find limiting mechanisms of the growth rate and to examine the morphology of grown layers. Coverage by 3C-SiC increases when increasing temperature, however more twins appeared. Activation energy of the growth is 130 kcal/mol--showing that growth rate limiting mechanism is sublimation of the source. We discuss the influence of large area 6H-SiC wafers on the formation of 3C-SiC, in which the change in basal plane orientation could also influence the growth of 3C-SiC.

  7. Seismicity in South Carolina

    USGS Publications Warehouse

    Shedlock, K.M.

    1988-01-01

    The largest historical earthquake in South Carolina, and in the southeastern US, occurred in the Coastal Plain province, probably northwest of Charleston, in 1886. Locations for aftershocks associated with this earthquake, estimated using intensities based on newspaper accounts, defined a northwest trending zone about 250 km long that was at least 100 km wide in the Coastal Plain but widened to a northeast trending zone in the Piedmont. The subsequent historical and instrumentally recorded seismicity in South Carolina images the 1886 aftershock zone. Instrumentally recorded seismicity in the Coastal Plain province occurs in 3 seismic zones or clusters: Middleton Place-Summervile (MPSSZ), Adams Run (ARC), and Bowman (BSZ). Approximately 68% of the Coastal Plain earthquakes occur in the MPSSZ, a north trending zone about 22 km long and 12 km wide, lying about 20 km northwest of Charleston. The hypocenters of MPSSZ earthquakes range in depth from near the surface to almost 12 km. Thrust, strike-slip, and some normal faulting are indicated by the fault plane solutions for Coastal Plain earthquakes. The maximum horizontal compressive stress, inferred from the P-axes of the fault plane solutions, is oriented NE-SW in the shallow crust (<9 km deep) but appears to be diffusely E-W between 9 to 12 km deep. -from Author

  8. Historical seismicity

    USGS Publications Warehouse

    Dengler, L.

    1992-01-01

    The North Coast region of California in the vicinity of Cape Mendocino is one of the state's most seismically active areas, accounting for 25 percent of seismic energy release in California during the last 50 years. the region is located in a geologically dynamic are surrounding the Mendocino triple junction where three of the Earth's tectonic plates join together ( see preceding article by Sam Clarke). In the historic past the North Coast has been affected by earthquakes occurring on the San Andreas fault system to the south, the Mendocino fault to the southwest, and intraplate earthquakes within both the Gorda and North American plates. More than sixty of these earthquakes have caused damage since the mid-1800's. Recent studies indicate that California's North Coast is also at risk with respect to very large earthquakes (magnitude >8) originating along the Cascadia subduction zone. Although the subduction zone has not generated great earthquakes in historic time, paleoseismic evidence suggests that such earthquakes have been generated by the subduction zone in the recent prehistoric past. 

  9. Seismic monitoring of torrential and fluvial processes

    NASA Astrophysics Data System (ADS)

    Burtin, Arnaud; Hovius, Niels; Turowski, Jens M.

    2016-04-01

    In seismology, the signal is usually analysed for earthquake data, but earthquakes represent less than 1 % of continuous recording. The remaining data are considered as seismic noise and were for a long time ignored. Over the past decades, the analysis of seismic noise has constantly increased in popularity, and this has led to the development of new approaches and applications in geophysics. The study of continuous seismic records is now open to other disciplines, like geomorphology. The motion of mass at the Earth's surface generates seismic waves that are recorded by nearby seismometers and can be used to monitor mass transfer throughout the landscape. Surface processes vary in nature, mechanism, magnitude, space and time, and this variability can be observed in the seismic signals. This contribution gives an overview of the development and current opportunities for the seismic monitoring of geomorphic processes. We first describe the common principles of seismic signal monitoring and introduce time-frequency analysis for the purpose of identification and differentiation of surface processes. Second, we present techniques to detect, locate and quantify geomorphic events. Third, we review the diverse layout of seismic arrays and highlight their advantages and limitations for specific processes, like slope or channel activity. Finally, we illustrate all these characteristics with the analysis of seismic data acquired in a small debris-flow catchment where geomorphic events show interactions and feedbacks. Further developments must aim to fully understand the richness of the continuous seismic signals, to better quantify the geomorphic activity and to improve the performance of warning systems. Seismic monitoring may ultimately allow the continuous survey of erosion and transfer of sediments in the landscape on the scales of external forcing.

  10. How Forgetful are Seismic Waves ?

    NASA Astrophysics Data System (ADS)

    Milkereit, B.

    2005-05-01

    3D surface seismic and vertical seismic profiling (VSP) techniques can be employed to image crustal structures in complex geological settings. The effects of heterogeneities on seismic wave propagation can be described in terms of different propagation regimes (Wu, 1989): quasi-homogeneous for heterogeneities too small to be seen by seismic waves, Rayleigh scattering, Mie scattering and small-angle scattering. These scattering regimes cause characteristic amplitude, phase and travel time fluctuation, which can be used to obtain estimates of scale length. Horizontal resolution of exploration seismic data is often discussed in terms of Fresnel zone. For surface and VSP data, the Fresnel radius increases with increasing depth of investigation. In addition, the lateral resolution is limited by the effective frequency content of the seismic signal. Based on strong contrast in petrophysical data, crustal exploration targets (such as gas-hydrates, permafrost or massive sulfide ores) should make strong P-wave, S-wave and converted wave reflectors against most background velocity models. In the context of realistic geological models, 3D numerical simulations are required to better assess elastic wave interactions with high acoustic impedance targets. In addition, it is important to study the influence of composition and shape of high acoustic impedance targets on the full scattered wavefield through a series of numerical modeling experiments based on the 3D elastic finite-difference (FD) method. Massive sulfide ores consisting of the end-member sulfide minerals pyrite, sphalerite, and galena, which span the full range of observed P- and S- wave velocities and densities in ore rocks, as well as gabbro inclusions, are investigated for different shapes which represent the complex morphologies often observed for ore deposits. 3D FD modeling reveals that large ore deposits lead to a strong and complex scattering response that is often dominated by shear-wave events (Bohlen et al

  11. Preparation of Pt supported on WO 3-C with enhanced catalytic activity by microwave-pyrolysis method

    NASA Astrophysics Data System (ADS)

    Ye, Jilei; Liu, Jianguo; Zou, Zhigang; Gu, Jun; Yu, Tao

    The WO 3-C hybrid materials are prepared by intermittently microwave-pyrolysis using ammonium tungstate as the precursor, and then Pt nano-particles are deposited by microwave-assited polyol process on WO 3-C. The TEM images show the dispersion of ∼10 nm WO 3 particles size supported on carbon and ∼3 nm Pt metal crystallites supported on WO 3-C. XRD results illustrate that WO 3 presented as monoclinic phase and the content of WO 3 in WO 3/C and Pt/WO 3-C catalysts is further characterized by EDAX. Furthermore, XPS characterizations indicate that the interaction between Pt and WO 3 is dramatically enhanced after heat treatment at 200 °C. The activities of Pt/WO 3-C for the electrochemical oxidation of methanol are compared with Pt/C in acid solution by cyclic voltammetry, CO-stripping and chronoaperometry. Pt/WO 3-C catalyst calcined at 200 °C exhibits the highest activity per electrochemical active surface area for methanol oxidation and is 60 mV more negative for CO electro-oxidation than that of Pt/C and Pt/WO 3-C without heat treatment. The great enhancement of electrochemical performance may be due to the improvement of the synergistic effect between Pt and WO 3 in Pt/WO 3-C catalyst after heat treatment.

  12. Fine Structure in 3C 120 and 3C 84. Ph.D. Thesis - Maryland Univ., 24 Aug. 1976

    NASA Technical Reports Server (NTRS)

    Hutton, L. K.

    1976-01-01

    Seven epochs of very long baseline radio interferometric observations of the Seyfert galaxies 3C 120 and 3C 84, at 3.8-cm wave length using stations at Westford, Massachusetts, Goldstone, California, Green Bank, West Virginia, and Onsala, Sweden, have been analyzed for source structure. An algorithm for reconstructing the brightness distribution of a spatially confined source from fringe amplitude and so called closure phase data has been developed and successfully applied to artificially generated test data and to data on the above mentioned sources. Over the two year time period of observation, 3C 120 was observed to consist of a double source showing apparent super relativistic expansion and separation velocities. The total flux changes comprising one outburst can be attributed to one of these components. 3C 84 showed much slower changes, evidently involving flux density changes in individual stationary components rather than relative motion.

  13. Capacitance of Ti3C2Tx MXene in ionic liquid electrolyte

    NASA Astrophysics Data System (ADS)

    Lin, Zifeng; Barbara, Daffos; Taberna, Pierre-Louis; Van Aken, Katherine L.; Anasori, Babak; Gogotsi, Yury; Simon, Patrice

    2016-09-01

    Ti3C2Tx MXene, a two-dimensional (2D) early transition metal carbide, has shown an extremely high volumetric capacitance in aqueous electrolytes, but in a narrow voltage window (less than 1.23 V). The utilization of MXene materials in ionic liquid electrolytes with a large voltage window has never been addressed. Here, we report the preparation of the Ti3C2Tx MXene ionogel film by vacuum filtration for use as supercapacitor electrodes operating in 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMI-TFSI) neat ionic liquid electrolyte. Due to the disordered structure of the Ti3C2Tx hydrogel film and a stable spacing after vacuum drying, achieved through ionic liquid electrolyte immersion of the Ti3C2Tx hydrogel film, the Ti3C2Tx surface became accessible to EMI+ and TFSI- ions. A capacitance of 70 F g-1 together with a large voltage window of 3 V was obtained at a scan rate of 20 mV s-1 in neat EMI-TFSI electrolyte. The electrochemical signature indicates a capacitive behavior even at a high scan rate (500 mV s-1) and a high power performance. This work opens up the possibilities of using MXene materials with various ionic liquid electrolytes.

  14. RXTE, VLBA, Optical, and Radio Monitoring of the Quasars 3C 279, PKS 1510--089, and 3C 273

    NASA Technical Reports Server (NTRS)

    Marscher, A. P.; Jorstad, S. G.; Aller, M. F.; McHardy, I. M.; Balonek, T. J.

    2001-01-01

    We are continuing our combined RXTE X-ray, VLBA imaging (at 43 GHz), optical (several observatories), and radio (University of Michigan Radio Astronomy Observatory) monitoring of the quasars 3C 279 and PKS 1510-089, and have started similar monitoring of 3C 273. X-ray flares in 3C 279 and PKS 1510-089 are associated with ejections of superluminal components. In addition, there is a close connection between the optical and X-ray variability of 3C 279. There is a strong correlation between the 14.5 GHz and X-ray variability of PKS 1510-089 in 1997 and 1998 (with the radio leading the X-ray) that becomes weaker in subsequent years. X-ray fluctuations occur on a variety of timescales in 3C 273, with a major prolonged outburst in mid-2001. The lead author will discuss the correlations in terms of inverse Compton models for the X-ray emission coupled with synchrotron models for the lower-frequency radiation. Synchrotron self-Compton models can explain the "reverse" time lag in PKS 1510-089 is well as the variable correlation between the X-ray variations and those at lower frequencies in this object and in 3C 279.

  15. The use of a Tunnel Boring Machine (TBM) as a seismic source

    NASA Astrophysics Data System (ADS)

    Kreutzer, Ingrid; Chwatal, Werner; Radinger, Alexander; Brückl, Ewald

    2014-05-01

    The Tunnel Seismic While Drilling (TSWD) method uses the Tunnel Boring Machine (TBM) as the seismic source. The method has been developed to predict the geological situation from reflections ahead of the tunnel face without disturbing the tunneling. The vibrations of the TBM are continuously monitored near the drilling head (pilot signal) as well as the direct and reflected seismic wave field at borehole geophones (geophone signal) situated in the tunnel wall behind the TBM. During the processing these signals are correlated and result in excellent seismic traces comparable to conventional seismic methods. The interpretation of the reflections leads to a nearly daily prognosis about 100 m ahead of the TBM. This system was successfully implemented at three different construction sites in Austria and is currently operating at one further. The cutters on front of the TBM head are pressed against the tunnel face and split the rock during rotating which is called the chipping process. This cutting process generates seismic waves radiated into the rock mass and results also in vibrations of the TBM itself. On the one hand it is important to know the source mechanism of the TBM and the radiation pattern of the seismic waves in all directions. Until now this is not well understood. To investigate this 3C-geophones were installed at the surface above the tunnel axis at different construction sites. The obtained seismograms show the forward and backward radiated seismic wave field of the TBM, for the present without consideration of the influence of the free surface. We compare this data with modelled seismograms in which we use different possible source mechanism, like single force or force due to tensile cracks. First results are shown in the scope of this work. On the other hand it is essential to know how good the recorded pilot signal represents the entire chipping process. Due to technically reasons the pilot signal has been registered so far on the non-rotating part

  16. Seismic sources

    DOEpatents

    Green, M.A.; Cook, N.G.W.; McEvilly, T.V.; Majer, E.L.; Witherspoon, P.A.

    1987-04-20

    Apparatus is described for placement in a borehole in the earth, which enables the generation of closely controlled seismic waves from the borehole. Pure torsional shear waves are generated by an apparatus which includes a stator element fixed to the borehole walls and a rotor element which is electrically driven to rapidly oscillate on the stator element to cause reaction forces transmitted through the borehole walls to the surrounding earth. Longitudinal shear waves are generated by an armature that is driven to rapidly oscillate along the axis of the borehole, to cause reaction forces transmitted to the surrounding earth. Pressure waves are generated by electrically driving pistons that press against opposite ends of a hydraulic reservoir that fills the borehole. High power is generated by energizing the elements for more than about one minute. 9 figs.

  17. Polarization-maintaining amplifier based on 3C fiber structures

    NASA Astrophysics Data System (ADS)

    Enokidani, Jun; Ito, Rumi; Sakurai, Tsutomu; Shin, Sumida; Tei, Kazuyoku

    2015-03-01

    Chirally-Coupled-Core (3C) fiber structure can preserve a single mode quality and even a linear polarization for a large core size. A principal advantage of fiber laser is its compatibility with monolithic integration and robust system. But so far, devices such as a combiner using the 3C fibers have not been reported. Here we report the first demonstration of such monolithic amplifier structure which contains an active fiber and a combiner based on 3C fibers. A single-stage amplifier is seeded by an EO Q-switched micro-laser and pumped by two high power fiber pigtailed 976-nm laser diodes via an in-house fabricated (2 + 1) × 1 pump signal combiner. The active fiber is based on a 3-m-long, 3C Yb-doped fiber (33 μm/250 μm core/cladding diameter with 0.06/0.46 NA). The amplifier demonstrates scaling up to 30W average power and 150 kW peak power in 0.3mJ, 2ns pulses. The beam profiles and beam qualities were characterized as its output power was varied up to 30W. The beam profile was maintained at a high beam quality of around M2=1.2. The spectral properties of the 3C fiber were also characterized as its output peak power was varied.

  18. Hydrocarbon Induced Seismicity in Northern Netherlands

    NASA Astrophysics Data System (ADS)

    Dost, B.; Spetzler, J.; Kraaijpoel, D.; Caccavale, M.

    2015-12-01

    The northern Netherlands has been regarded aseismic until the first earthquakes started in 1986, after more than 25 years of gas production from the one of the largest on-shore gas-fields in the World, the Groningen field, and accompanying smaller gas fields. Due to the shallow sources, at approximately 3 km depth, even small magnitude events cause considerable damage to buildings in the region. Since the largest recorded event in the Groningen field in 2012 with ML= 3,6, more than 30.000 damage claims were received by the mining company. Since 1995 a seismic monitoring network is operational in the region, consisting of 8 200m deep boreholes with 4 levels of 3C 4,5 Hz geophones. The network was designed for a location threshold of ML=1,5 over a 40x 80 km region. Average station separation was 20 km. At the end of 2014, 245 events have been recorded with ML ≥ 1,5, out of a total of 1100. Since 2003 a new mining law is in place in the Netherlands, which requires for each gas field in production a seismic risk analysis. Initially, due to the small number of events for specific fields, a general hazard (PSHA) was calculated for all gas-fields and a maximum magnitude was estimated at ML = 3,9. Since 2003 an increase in the activity rate is observed for the Groningen field, leading to the development of new models and a re-assessment of parameters like the maximum magnitude. More recently these models are extended to seismic risk, where also the fragility of the regional buildings is taken into account. Understanding the earthquake process is essential in taking mitigation measures. Continued research is focused on reducing the uncertainties in the hazard and risk models and is accompanied by an upgrade of the monitoring network. In 2014 a new dense network was designed to monitor the Groningen gas field in this region (30*40 km) with an average separation of 4 km. This allows an improved location threshold (M>0,5) and location accuracy (50-100m). A detailed P- and S

  19. Stochastic excitation of seismic waves by a hurricane

    NASA Astrophysics Data System (ADS)

    Tanimoto, Toshiro; Valovcin, Anne

    2015-11-01

    We investigate how a tropical cyclone (Hurricane Isaac in 2012) generated seismic ground motions using seismic and barometric data from the Earthscope network. In the frequency band 0.01-0.02 Hz, seismic and surface pressure amplitudes show a systematic decreasing trend with distance from the center of the hurricane. However, the decreasing rate is much higher for seismic waves than for pressure. We develop a stochastic theory of seismic wave excitation by surface pressure that connects these two observed data sets; surface pressure is the excitation source, and seismic data are the resulting seismic wave field. This theory contains two parameters: (i) the pressure power spectral density (Sp) and (ii) the correlation length in the pressure field (L). Using the formula, we solve for the spatial variation of correlation lengths. The solution shows that longer correlation lengths in pressure are near the hurricane center. Because seismic wave excitation is proportional to L2Sp, the excitation for seismic waves becomes effectively more localized closer to the center. Also, the scaling relation between L and Sp leads to an excitation source which is approximately proportional to the third power of surface pressure. This centralized source for seismic wave excitation explains why the decreasing rate with distance is higher for seismic data than for barometric data. However, this spatial coherence mechanism may not be the only process, as strong turbulence near the center may cause transient bursts of pressure and also induce higher temporal correlation. These alternative mechanisms need to be carefully analyzed in the future.

  20. Improved visible light driven photoelectrochemical properties of 3C-SiC semiconductor with Pt nanoparticles for hydrogen generation

    SciTech Connect

    Tae Song, Jun; Kamiya, Masayuki; Iwasaki, Takayuki; Hatano, Mutsuko; Mashiko, Hisanori; Ohtomo, Akira; Nakamine, Yoshifumi

    2013-11-18

    We propose the n-type 3C-SiC with Pt nanoparticles (Pt NPs) as photo-anode for photoelectrochemical hydrogen (H{sub 2}) generation. We found that band-edge structure of 3C-SiC is suitable for H{sub 2} generation, and the property can be optimized by dopant (nitrogen) concentration in 3C-SiC. We also confirmed that Pt NPs enhance photoelectrochemical properties showing 0.2%–0.8% higher Incident Photon-to-Current Efficiency than bare 3C-SiC in visible wavelength despite diminished light absorption. Solar-conversion efficiency increases approximately 6.3 times, and H{sub 2} production is improved by 6.5 times with 33% of Faradaic efficiency. Lastly, 3C-SiC surface corrosion is effectively inhibited.

  1. Seismic Holography of Solar Activity

    NASA Technical Reports Server (NTRS)

    Lindsey, Charles

    2000-01-01

    The basic goal of the project was to extend holographic seismic imaging techniques developed under a previous NASA contract, and to incorporate phase diagnostics. Phase-sensitive imaging gives us a powerful probe of local thermal and Doppler perturbations in active region subphotospheres, allowing us to map thermal structure and flows associated with "acoustic moats" and "acoustic glories". These remarkable features were discovered during our work, by applying simple acoustic power holography to active regions. Included in the original project statement was an effort to obtain the first seismic images of active regions on the Sun's far surface.

  2. Romanian Educational Seismic Network Project

    NASA Astrophysics Data System (ADS)

    Tataru, Dragos; Ionescu, Constantin; Zaharia, Bogdan; Grecu, Bogdan; Tibu, Speranta; Popa, Mihaela; Borleanu, Felix; Toma, Dragos; Brisan, Nicoleta; Georgescu, Emil-Sever; Dobre, Daniela; Dragomir, Claudiu-Sorin

    2013-04-01

    Romania is one of the most active seismic countries in Europe, with more than 500 earthquakes occurring every year. The seismic hazard of Romania is relatively high and thus understanding the earthquake phenomena and their effects at the earth surface represents an important step toward the education of population in earthquake affected regions of the country and aims to raise the awareness about the earthquake risk and possible mitigation actions. In this direction, the first national educational project in the field of seismology has recently started in Romania: the ROmanian EDUcational SEISmic NETwork (ROEDUSEIS-NET) project. It involves four partners: the National Institute for Earth Physics as coordinator, the National Institute for Research and Development in Construction, Urban Planning and Sustainable Spatial Development " URBAN - INCERC" Bucharest, the Babeş-Bolyai University (Faculty of Environmental Sciences and Engineering) and the software firm "BETA Software". The project has many educational, scientific and social goals. The main educational objectives are: training students and teachers in the analysis and interpretation of seismological data, preparing of several comprehensive educational materials, designing and testing didactic activities using informatics and web-oriented tools. The scientific objective is to introduce into schools the use of advanced instruments and experimental methods that are usually restricted to research laboratories, with the main product being the creation of an earthquake waveform archive. Thus a large amount of such data will be used by students and teachers for educational purposes. For the social objectives, the project represents an effective instrument for informing and creating an awareness of the seismic risk, for experimentation into the efficacy of scientific communication, and for an increase in the direct involvement of schools and the general public. A network of nine seismic stations with SEP seismometers

  3. Optical variability of PHL 1811 and 3C 273

    NASA Astrophysics Data System (ADS)

    Fan, J. H.; Kurtanidze, O.; Liu, Y.; Yuan, Y. H.; Hao, J. M.; Cai, W.; Xiao, H. B.; Pei, Z. Y.

    2015-03-01

    In this work, we reported the optical photometry monitoring results for two brightest nearby quasars, PHL 1811 and 3C 273 using the ST-6 camera at Abastumani Observatory, Georgia. For PHL 1811, we found 3 microvariability events with time scale of ΔT = 6.0 min. For 3C273, we found that the largest variations are ΔV = 0.369 +/- 0.028 mag, ΔR = 0.495 +/- 0.076 mag, and ΔI = 0.355 +/- 0.009 mag. When periodicity analysis methods are adopted to the available data, a period of p = 5.80 +/- 1.12 years is obtained for PHL 1811, and p = 21.10 +/- 0.14, 10.00 +/- 0.14, 7.30 +/- 0.09, 13.20 +/- 0.09, 2.10 +/- 0.06, and 0.68 +/- 0.05 years are obtained for 3C 273.

  4. Energetics and structural stability of Cs3C60

    SciTech Connect

    Saito, Susumu; Umemoto, Koichiro; Louie, Steven G.; Cohen, MarvinL.

    2003-12-15

    Using the ab initio pseudo potential total-energy method and the density-functional theory, we study the energetics of face-centered-cubic Cs3C60 which is a material of great interest as a possible high transition-temperature superconductor. At the optimized lattice constant the volume per C60 is found to be smaller than the most stable hexagon-coordination A15 phase, while the total energy of the fcc phase is about 0.9 eV higher than the A15 phase. These results indicate that a low-temperature and high-pressure synthesis method might be a possible way to produce the fcc Cs3C60 phase. In addition, it is also found that the A15 Cs3C60 should show a phase transformation from a hexagon-coordination phase to a pentagon-coordination phase under hydrostatic pressure.

  5. Seismic modeling of fluvial reservoirs in outcrop

    SciTech Connect

    Campbell, E. )

    1993-09-01

    Three-dimensional (3-D) seismics and concomitant improvements in processing techniques have increased the amount of reservoir-scale information that can be obtained from the seismic waveform reaching the surface. However, the geological significance of these seismic events remains unclear. The seismic modeling of reservoir formations in outcrops allows analogs to be drawn to the seismic response of reservoirs at depth. Previous outcrop modeling studies are mostly high-frequency approximations, suitable for large-scale geometrical imaging but unsuitable for imaging lateral variations in lithology and geometry of bodies that lie on or below the [open quotes]visual[close quotes] resolution of the seismic tool. This study examines finite-difference seismic modeling of Tertiary, fluvial-sandstone bodies in outcrop from central Spain. The outcrops were well known from reservoir characterization studies, easily accessible, and well exposed. Outcrop geometry was converted into a finite-difference grid, with density and velocity values coming from measurements of cores and blocks from each of the lithologies. Synthetic traces were generated. The traces were then processed in the conventional manner. Full solution of the wave equation allows all wave types to be modeled, e.g., diffraction sand multiples. Models were generated to simulate reservoir conditions at the surface and at depth. Seismic wave-forms could then be related back to reservoir characteristics. Seismic modeling of reservoir sands in outcrop can aid in the interpretation of such bodies at depth. Seismic modeling of reservoirs is a low-cost interpretation tool that may aid field development by delineation of reservoirs in area of complex sedimentology where surface analogs exist.

  6. Automating Shallow Seismic Imaging

    SciTech Connect

    Steeples, Don W.

    2004-12-09

    This seven-year, shallow-seismic reflection research project had the aim of improving geophysical imaging of possible contaminant flow paths. Thousands of chemically contaminated sites exist in the United States, including at least 3,700 at Department of Energy (DOE) facilities. Imaging technologies such as shallow seismic reflection (SSR) and ground-penetrating radar (GPR) sometimes are capable of identifying geologic conditions that might indicate preferential contaminant-flow paths. Historically, SSR has been used very little at depths shallower than 30 m, and even more rarely at depths of 10 m or less. Conversely, GPR is rarely useful at depths greater than 10 m, especially in areas where clay or other electrically conductive materials are present near the surface. Efforts to image the cone of depression around a pumping well using seismic methods were only partially successful (for complete references of all research results, see the full Final Technical Report, DOE/ER/14826-F), but peripheral results included development of SSR methods for depths shallower than one meter, a depth range that had not been achieved before. Imaging at such shallow depths, however, requires geophone intervals of the order of 10 cm or less, which makes such surveys very expensive in terms of human time and effort. We also showed that SSR and GPR could be used in a complementary fashion to image the same volume of earth at very shallow depths. The primary research focus of the second three-year period of funding was to develop and demonstrate an automated method of conducting two-dimensional (2D) shallow-seismic surveys with the goal of saving time, effort, and money. Tests involving the second generation of the hydraulic geophone-planting device dubbed the ''Autojuggie'' showed that large numbers of geophones can be placed quickly and automatically and can acquire high-quality data, although not under rough topographic conditions. In some easy-access environments, this device could

  7. Natural fracture characterization using passive seismic illumination

    SciTech Connect

    Nihei, K.T.

    2003-01-08

    The presence of natural fractures in reservoir rock can significantly enhance gas production, especially in tight gas formations. Any general knowledge of the existence, location, orientation, spatial density, and connectivity of natural fractures, as well as general reservoir structure, that can be obtained prior to active seismic acquisition and drilling can be exploited to identify key areas for subsequent higher resolution active seismic imaging. Current practices for estimating fracture properties before the acquisition of surface seismic data are usually based on the assumed geology and tectonics of the region, and empirical or fracture mechanics-based relationships between stratigraphic curvature and fracturing. The objective of this research is to investigate the potential of multicomponent surface sensor arrays, and passive seismic sources in the form of local earthquakes to identify and characterize potential fractured gas reservoirs located near seismically active regions. To assess the feasibility of passive seismic fracture detection and characterization, we have developed numerical codes for modeling elastic wave propagation in reservoir structures containing multiple, finite-length fractures. This article describes our efforts to determine the conditions for favorable excitation of fracture converted waves, and to develop an imaging method that can be used to locate and characterize fractures using multicomponent, passive seismic data recorded on a surface array.

  8. 3C-SiC nanocrystals/TiO{sub 2} nanotube heterostructures with enhanced photocatalytic performance

    SciTech Connect

    Zhang, J.; Liu, L. Z.; Yang, L.; Gan, Z. X.; Wu, X. L. E-mail: paul.chu@cityu.edu.hk; Chu, Paul K. E-mail: paul.chu@cityu.edu.hk

    2014-06-09

    p-type ultrathin 3C-SiC nanocrystals are coated on heat-treated n-type TiO{sub 2} nanotube arrays formed by electrochemical etching of Ti sheets to produce heterostructured photocatalysts. Depending on the amounts of 3C-SiC nanocrystals on the TiO{sub 2} nanotubes, photocatalytic degradation of organic species can be enhanced. The intrinsic electric field induced by the heterojunction promotes separation of the photoexcited electrons-holes in both the TiO{sub 2} nanotubes and 3C-SiC nanocrystals. Hence, holes can more effectively travel to the surface of 3C-SiC nanocrystals and there are more electrons on the surface of TiO{sub 2} nanotubes consequently forming more {sup •}O{sub 2}{sup −} and {sup •}OH species to degrade organic molecules.

  9. The linear polarization of 3C 345 in the ultraviolet

    NASA Technical Reports Server (NTRS)

    Dolan, Joseph F.; Boyd, Patricia T.; Wolinski, Karen G.; Smith, Paul S.; Impey, C. D.; Bless, Robert C.; Nelson, M. J.; Percival, J. W.; Taylor, M. J.; Elliot, J. L.

    1994-01-01

    The linear polarization of 3C 345, a superluminal radio source and OVV quasar, was observed in two bandpasses in the ultraviolet (centered at 2160 A and 2770 A) in 1993 April using the High Speed Photometer on the Hubble Space Telescope. The quasar is significantly polarized in the UV (p greater than 5%). Ground-based polarimetry was obtained 11 days later, but a difference in the position angle between the observations in the visible and those in the UV indicate that the magnitude of the polarization of 3C 345 may have changed over that time. If the two observation sets represent the same state of spectral polarization, then the large UV flux implies that either the polarization of the synchrotron continuum must stop decreasing in the UV, or that there is an additional source of polarized flux in the ultraviolet. Only if the UV observations represent a spectral polarization state with the same position angle in the visible seen previously in 3C 345 can the polarized flux be represented by a single power law consistent with the three-component model of Smith et al. This model consists of a polarized synchrotron component, an unpolarized component from the broad-line region, and an unpolarized component attributed to thermal radiation from an optically thick accretion disk. Additional simultaneous polarimetry in the UV and visible will be required to further constrain models of the continuum emission processes in 3C 345 and determine if the UV polarized flux is synchrotron in origin.

  10. Microwave Radiometer – 3 Channel (MWR3C) Handbook

    SciTech Connect

    Cadeddu, MP

    2012-05-04

    The microwave radiometer 3-channel (MWR3C) provides time-series measurements of brightness temperatures from three channels centered at 23.834, 30, and 89 GHz. These three channels are sensitive to the presence of liquid water and precipitable water vapor.

  11. Revisiting correlations between broad-line and jet emission variations for AGNs: 3C 120 and 3C 273

    NASA Astrophysics Data System (ADS)

    Liu, H. T.; Bai, J. M.; Feng, H. C.; Li, S. K.

    2015-06-01

    We restudy the issue of cross-correlations between broad-line and jet emission variations, and aim to locate the position of a radio (and gamma-ray) emitting region in a jet of active galactic nuclei. Considering the radial profiles of the radius and number density of clouds in a spherical broad-line region (BLR), we derive new formulae connecting the jet-emitting position Rjet to the time lag τob between broad-line and jet emission variations, and the BLR radius. Also, formulae are derived for a disc-like BLR and a spherical shell BLR. The model-independent flux randomization/random subset selection method is used to estimate τob. For 3C 120, positive lags of about 0.3 yr are found between the 15 GHz emission and the Hβ, Hγ and He II λ4686 lines, including broad-line data in a newly published paper, indicating that the line variations lead the 15 GHz ones. Each of the broad-line light curves corresponds to a radio outburst. Rjet = 1.1-1.5 parsec (pc) is obtained for 3C 120. For 3C 273, a common feature of negative time lags is found in the cross-correlation functions between light curves of radio emission and the Balmer lines, as well as Lyα λ1216 and C IV λ1549 lines. Rjet = 1.0-2.6 pc is obtained for 3C 273. The estimated Rjet is comparable for 3C 120 and 3C 273, and the gamma-ray-emitting positions will be within ˜1-3 pc from the central engines. Comparisons show that the cloud number density and radius radial distributions and the BLR structures have only negligible effects on Rjet.

  12. Seismic sources

    DOEpatents

    Green, Michael A.; Cook, Neville G. W.; McEvilly, Thomas V.; Majer, Ernest L.; Witherspoon, Paul A.

    1992-01-01

    Apparatus is described for placement in a borehole in the earth, which enables the generation of closely controlled seismic waves from the borehole. Pure torsional shear waves are generated by an apparatus which includes a stator element fixed to the borehole walls and a rotor element which is electrically driven to rapidly oscillate on the stator element to cause reaction forces transmitted through the borehole walls to the surrounding earth. Logitudinal shear waves are generated by an armature that is driven to rapidly oscillate along the axis of the borehole relative to a stator that is clamped to the borehole, to cause reaction forces transmitted to the surrounding earth. Pressure waves are generated by electrically driving pistons that press against opposite ends of a hydraulic reservoir that fills the borehole. High power is generated by energizing the elements at a power level that causes heating to over 150.degree. C. within one minute of operation, but energizing the elements for no more than about one minute.

  13. A description of seismic amplitude techniques

    NASA Astrophysics Data System (ADS)

    Shadlow, James

    2014-02-01

    The acquisition of seismic data is a non-invasive technique used for determining the sub surface geology. Changes in lithology and fluid fill affect the seismic wavelet. Analysing seismic data for direct hydrocarbon indicators (DHIs), such as full stack amplitude anomalies, or amplitude variation with offset (AVO), can help a seismic interpreter relate the geophysical response to real geology and, more importantly, to distinguish the presence of hydrocarbons. Inversion is another commonly used technique that attempts to tie the seismic data back to the geology. Much has been written about these techniques, and attempting to gain an understanding on the theory and application of them by reading through various journals can be quite daunting. The purpose of this paper is to briefly outline DHI analysis, including full stack amplitude anomalies, AVO and inversion and show the relationship between all three. The equations presented have been included for completeness, but the reader can pass over the mathematical detail.

  14. Testing the USGS 3D San Francisco Bay Area Seismic Velocity Model using Observations of 0.5 to 2 s Surface Waves from Local and Regional Earthquakes (Invited)

    NASA Astrophysics Data System (ADS)

    Brocher, T. M.; Frankel, A. D.; Oppenheimer, D. H.; Fletcher, J. B.; Luetgert, J. H.

    2010-12-01

    We summarize recent observations of long-period (0.5 - 2 s) seismic waves from seven local and regional earthquakes in the magnitude range 3.5 - 6.5, made using accelerograph arrays in the Sacramento/San Joaquin Delta, in the San Leandro basin, and in the Livermore Valley. The observations were made on both isolated accelerometers (both NetQuakes and traditional instruments) and on arrays consisting of clusters of 3 instruments with an aperture of 200-300 meters. These recordings demonstrate that large-amplitude, long-period surface wave arrivals are commonly observed in the urbanized low-lying areas in the East Bay. In the Sacramento/San Joaquin Delta, late arriving Rayleigh waves observed on the vertical component have apparent velocities of about 610 m/s although they range from 300 to 1000 m/s for waves having a period of about 2 s. The azimuth of the arrivals is within 20 degrees of that expected for direct propagation from the epicenters indicating that they are related to the low seismic velocity of the shallow sediments in the Great Valley. Strong basin surface waves produced by the September 6, 2008 M4.1 Alamo earthquake observed throughout San Leandro and Oakland substantially increase the duration of shaking at periods of 1 sec and longer. These basin surface waves exhibit dispersion with group velocities as low as about 300 m/s and are apparent at frequencies from 0.8 - 2 s. These observations indicate that relatively shallow sedimentary basins, such as the San Leandro basin with a sediment thickness of about 1 km, support sizeable basin surface waves that amplify and prolong ground shaking. The M4.1 Alamo earthquake also produced a strong basin surface wave in the Livermore Valley, observed by our array in Pleasanton, that strongly amplifies periods of 0.5 s and longer. Array analysis indicates that late arrivals represent surface waves from an azimuth more westerly than that of the hypocenter. These surface waves are currently not well modeled by the

  15. Connection Between X-Ray Emission and Relativistic Jets in the Radio Galaxies 3C 111 and 3C 120

    NASA Technical Reports Server (NTRS)

    Aller, Margo F.

    2005-01-01

    This work represents a part of a longterm study of the X-ray flux variability in radio galaxies and its relation to flux and structural changes in the associated radio jet. The work described here included: 1) continued study of the emission properties of the FR I radio galaxy 3C 120 known to exhibit a jet/disk connection from our past work; and 2) the commencement of monitoring of a second radio galaxy, the FR I1 object 3C 111 which was selected because of similar radio and X-ray properties to 3C 120, including the presence of Fe K a emission. The association between X-ray dips and new superluminal components, suggesting a picture in which the radio jet is fed by accretion events near the black hole, was identified in 3C 120 using combined RXTE and radio flux monitoring data and bi-monthly to monthly imaging data from the VLBA at 43 GHz. Such data were also obtained for both targets during the period described here. Specific goals were to more broadly investigate the X-ray dip/superluminal connection in 3C 120, thereby determining the epochs of X-ray minima and superluminal ejections more accurately (and hence more precisely determining the distance between the accretion disk and the core of the radio jet), and to determine whether a similar pattern is present in the data for a second radio galaxy. In 3C 111 a different time scale (longer time delays between X-ray dips and superluminal ejections) was expected due to the higher black hole mass implied by its higher radio luminosity: no black hole mass is published for this object but one can be determined from a PDS analysis of the RXTE data. The addition of the second source to the study would identify whether a similar connection was present in other sources and, if found, would provide important information on how time scale (and hence size scale) of accretion disk/jet systems depends on black hole mass. The grant included funding for the reduction and analysis of data obtained during the time period of Rossi

  16. Near-Surface Structure and Velocities of the Northeastern Santa Cruz Mountains and the Western Santa Clara Valley, California, From Seismic Imaging

    USGS Publications Warehouse

    Catchings, R.D.; Gandhok, G.; Goldman, M.R.; Steedman, Clare

    2007-01-01

    Introduction The Santa Clara Valley (SCV) is located in the southern San Francisco Bay area of California and is bounded by the Santa Cruz Mountains to the southwest, the Diablo Ranges to the northeast, and the San Francisco Bay to the north (Fig. 1). The SCV, which includes the City of San Jose, numerous smaller cities, and much of the high-technology manufacturing and research area commonly referred to as the Silicon Valley, has a population in excess of 1.7 million people (2000 U. S. Census;http://quickfacts.census.gov/qfd/states/06/06085.html The SCV is situated between major active faults of the San Andreas Fault system, including the San Andreas Fault to the southwest and the Hayward and Calaveras faults to the northeast, and other faults inferred to lie beneath the alluvium of the SCV (CWDR, 1967; Bortugno et al., 1991). The importance of the SCV as a major industrial center, its large population, and its proximity to major earthquake faults are important considerations with respect to earthquake hazards and water-resource management. The fault-bounded alluvial aquifer system beneath the valley is the source of about one-third of the water supply for the metropolitan area (Hanson et al., 2004). To better address the earthquake hazards of the SCV, the U.S. Geological Survey (USGS) has undertaken a program to evaluate potential seismic sources, the effects of strong ground shaking, and stratigraphy associated with the regional aquifer system. As part of that program and to better understand water resources of the valley, the USGS and the Santa Clara Valley Water District (SCVWD) began joint studies to characterize the faults, stratigraphy, and structures beneath the SCV in the year 2000. Such features are important to both agencies because they directly influence the availability and management of groundwater resources in the valley, and they affect the severity and distribution of strong shaking from local and regional earthquakes sources that may affect

  17. Fluid injection and induced seismicity

    NASA Astrophysics Data System (ADS)

    Kendall, Michael; Verdon, James

    2016-04-01

    The link between fluid injection, or extraction, and induced seismicity has been observed in reservoirs for many decades. In fact spatial mapping of low magnitude events is routinely used to estimate a stimulated reservoir volume. However, the link between subsurface fluid injection and larger felt seismicity is less clear and has attracted recent interest with a dramatic increase in earthquakes associated with the disposal of oilfield waste fluids. In a few cases, hydraulic fracturing has also been linked to induced seismicity. Much can be learned from past case-studies of induced seismicity so that we can better understand the risks posed. Here we examine 12 case examples and consider in particular controls on maximum event size, lateral event distributions, and event depths. Our results suggest that injection volume is a better control on maximum magnitude than past, natural seismicity in a region. This might, however, simply reflect the lack of baseline monitoring and/or long-term seismic records in certain regions. To address this in the UK, the British Geological Survey is leading the deployment of monitoring arrays in prospective shale gas areas in Lancashire and Yorkshire. In most cases, seismicity is generally located in close vicinity to the injection site. However, in some cases, the nearest events are up to 5km from the injection point. This gives an indication of the minimum radius of influence of such fluid injection projects. The most distant events are never more than 20km from the injection point, perhaps implying a maximum radius of influence. Some events are located in the target reservoir, but most occur below the injection depth. In fact, most events lie in the crystalline basement underlying the sedimentary rocks. This suggests that induced seismicity may not pose a leakage risk for fluid migration back to the surface, as it does not impact caprock integrity. A useful application for microseismic data is to try and forecast induced seismicity

  18. Ti3C2Tx Filler Effect on the Proton Conduction Property of Polymer Electrolyte Membrane.

    PubMed

    Liu, Yahua; Zhang, Jiakui; Zhang, Xiang; Li, Yifan; Wang, Jingtao

    2016-08-10

    Conductive polymer electrolyte membranes are increasingly attractive for a wide range of applications in hydrogen-relevant devices, for instance hydrogen fuel cells. In this study, two-dimensional Ti3C2Tx, a typical representative of the recently developed MXene family, is synthesized and employed as a universal filler for its features of large specific surface area, high aspect ratio, and sufficient terminated -OH groups. The Ti3C2Tx is incorporated into polymer matrix to explore its function on membrane microstructure and proton conduction property. Both phase-separated (acidic Nafion and sulfonated poly(ether ether ketone)) and non-phase-separated (basic chitosan) polymers are utilized as membrane matrixes. The microstructures, physicochemical properties, and proton conduction properties of the membranes are extensively investigated. It is demonstrated that Ti3C2Tx generates significant promotion effect on proton conduction of the composite membrane by facilitating both vehicle-type and Grotthuss-type proton transfer, yielding several times increased proton conductivity for every polymer-based composite membrane under various conditions, and the composite membrane achieves elevated hydrogen fuel cell performance. The stable Ti3C2Tx also reinforces the thermal and mechanical stabilities of these composite membranes. Since the MXene family includes more than 70 members, this exploration is expected to open up new perspectives for expanding their applications, especially as membrane modifiers and proton conductors. PMID:27430190

  19. Ti3C2Tx Filler Effect on the Proton Conduction Property of Polymer Electrolyte Membrane.

    PubMed

    Liu, Yahua; Zhang, Jiakui; Zhang, Xiang; Li, Yifan; Wang, Jingtao

    2016-08-10

    Conductive polymer electrolyte membranes are increasingly attractive for a wide range of applications in hydrogen-relevant devices, for instance hydrogen fuel cells. In this study, two-dimensional Ti3C2Tx, a typical representative of the recently developed MXene family, is synthesized and employed as a universal filler for its features of large specific surface area, high aspect ratio, and sufficient terminated -OH groups. The Ti3C2Tx is incorporated into polymer matrix to explore its function on membrane microstructure and proton conduction property. Both phase-separated (acidic Nafion and sulfonated poly(ether ether ketone)) and non-phase-separated (basic chitosan) polymers are utilized as membrane matrixes. The microstructures, physicochemical properties, and proton conduction properties of the membranes are extensively investigated. It is demonstrated that Ti3C2Tx generates significant promotion effect on proton conduction of the composite membrane by facilitating both vehicle-type and Grotthuss-type proton transfer, yielding several times increased proton conductivity for every polymer-based composite membrane under various conditions, and the composite membrane achieves elevated hydrogen fuel cell performance. The stable Ti3C2Tx also reinforces the thermal and mechanical stabilities of these composite membranes. Since the MXene family includes more than 70 members, this exploration is expected to open up new perspectives for expanding their applications, especially as membrane modifiers and proton conductors.

  20. Semipolar (202̅3) nitrides grown on 3C-SiC/(001) Si substrates

    NASA Astrophysics Data System (ADS)

    Dinh, Duc V.; Presa, S.; Akhter, M.; Maaskant, P. P.; Corbett, B.; Parbrook, P. J.

    2015-12-01

    Heteroepitaxial growth of GaN buffer layers on 3C-SiC/(001) Si templates (4°-offcut towards [110]) by metalorganic vapour phase epitaxy has been investigated. High-temperature grown Al0.5Ga0.5N/AlN interlayers were employed to produce a single (202̅3) GaN surface orientation. Specular crack-free GaN layers showed undulations along [11̅0]{}3{{C}-{SiC}/{Si}} with a root mean square roughness of about 13.5 nm (50 × 50 μm2). The orientation relationship determined by x-ray diffraction (XRD) was found to be [1̅21̅0]GaN ∥[11̅0]{}3{{C}-{SiC}/{Si}} and [3̅034]GaN ∥[110]3C - SiC/Si . Low-temperature photoluminescence (PL) and XRD measurements showed the presence of basal-plane stacking faults in the layers. PL measurements of (202̅3) multiple-quantum-well and light-emitting diode structures showed uniform luminescence at about 500 nm emission wavelength. A small peak shift of about 3 nm was observed in the electroluminescence when the current was increased from 5 to 50 mA (25-250 A cm-2).

  1. Seismic slip deficit along Nepal Himalayas: implications for seismic hazard

    NASA Astrophysics Data System (ADS)

    Bollinger, Laurent; Tapponnier, Paul; Nath Sapkota, Soma; Klinger, Yann

    2016-04-01

    In 1255, 1344 and 1408 AD, then again in 1833, 1934 and 2015, large earthquakes, devastated Kathmandu. The 1255 and 1934 surface ruptures have been identified east of the city, along comparable segments of the Main Frontal Thrust (MFT). Whether the other two pairs of events were similar, is unclear. Taking into account charcoal's "Inbuilt-ages", we revisit the timing of terrace offsets at key sites, to compare them with the seismic record since 1200 AD. The location, extent, and seismic moment of the 1833 and 2015 events imply that they released only a small part of the regional slip deficit, on a deep thrust segment that stopped north of the Siwaliks. By contrast, the 1344 or 1408 AD earthquake may have ruptured the MFT up to the surface in central Nepal between Kathmandu and Pokhara, East of the surface trace of the great 1505 AD earthquake which affected Western Nepal. If so, the whole megathrust system in Nepal ruptured during a sequence of earthquakes that lasted less than three centuries and propagated the rupture up to the surface from East to West. Today's situation in the himalayan seismic sequence might be close to that of the 14th century.

  2. X-Ray Monitoring of 3C120

    NASA Astrophysics Data System (ADS)

    Miller, Hugh

    The goal of this program is to characterize the variability at both X- ray and optical wavelengths simultaneously for the high luminosity, radio-loud AGN(RLAGN), 3C 120. The key question that is most central to the study of the variability of both RLAGN and radio-quiet AGN(RQAGN) is to identify a ''characteristic timescale", e.g. breaks (''knees") or spikes in the power density spectrum. There are now several RQAGN (e.g., NGC 3516 and Akn 120) for which characteristic timescales (i.e., knee frequencies) have been detected. However there is no RLAGN for which a knee frequency has been observed. The Seyfert-like RLAGN, 3C 120 offers a special opportunity for a possible first detection of a knee frequency in RLAGN.

  3. Erosion influences the seismicity of active thrust faults.

    PubMed

    Steer, Philippe; Simoes, Martine; Cattin, Rodolphe; Shyu, J Bruce H

    2014-11-21

    Assessing seismic hazards remains one of the most challenging scientific issues in Earth sciences. Deep tectonic processes are classically considered as the only persistent mechanism driving the stress loading of active faults over a seismic cycle. Here we show via a mechanical model that erosion also significantly influences the stress loading of thrust faults at the timescale of a seismic cycle. Indeed, erosion rates of about ~0.1-20 mm yr(-1), as documented in Taiwan and in other active compressional orogens, can raise the Coulomb stress by ~0.1-10 bar on the nearby thrust faults over the inter-seismic phase. Mass transfers induced by surface processes in general, during continuous or short-lived and intense events, represent a prominent mechanism for inter-seismic stress loading of faults near the surface. Such stresses are probably sufficient to trigger shallow seismicity or promote the rupture of deep continental earthquakes up to the surface.

  4. Seismic augmentation of acoustic monitoring of mortar fire

    NASA Astrophysics Data System (ADS)

    Anderson, Thomas S.

    2007-10-01

    The US Army Corps of Engineers Research and Development Center participated in a joint ARL-NATO TG-53 field experiment and data collect at Yuma Proving Ground, AZ in early November 2005. Seismic and acoustic signatures from both muzzle blasts and impacts of small arms fire and artillery were recorded using 7 seismic arrays and 3 acoustic arrays. Arrays comprised of 12 seismic and 12 acoustic sensors each were located from 700 m to 18 km from gun positions. Preliminary analysis of signatures attributed to 60mm, 81mm, 120 mm mortars recorded at a seismic-acoustic array 1.1 km from gun position are presented. Seismic and acoustic array f-k analysis is performed to detect and characterize the source signature. Horizontal seismic data are analyzed to determine efficacy of a seismic discriminant for mortar and artillery sources. Rotation of North and East seismic components to radial and transverse components relative to the source-receiver path provide maximum surface wave amplitude on the transverse component. Angles of rotation agree well with f-k analysis of both seismic and acoustic signals. The spectral energy of the rotated transverse surface wave is observable on the all caliber of mortars at a distance of 1.1 km and is a reliable source discriminant for mortar sources at this distance. In a step towards automation, travel time stencils using local seismic and acoustic velocities are applied to seismic data for analysis and determination of source characteristics.

  5. Seismic intrusion detector system

    DOEpatents

    Hawk, Hervey L.; Hawley, James G.; Portlock, John M.; Scheibner, James E.

    1976-01-01

    A system for monitoring man-associated seismic movements within a control area including a geophone for generating an electrical signal in response to seismic movement, a bandpass amplifier and threshold detector for eliminating unwanted signals, pulse counting system for counting and storing the number of seismic movements within the area, and a monitoring system operable on command having a variable frequency oscillator generating an audio frequency signal proportional to the number of said seismic movements.

  6. Voltammetry of Sc{sub 3}@C{sub 82}

    SciTech Connect

    Anderson, M.R.; Dorn, H.C.; Stevenson, S.; Burbank, P.M.; Gibson, J.R.

    1997-01-15

    This paper describes the first electrochemical data for a polymetallic endohedral metallofullerene. The voltammetric behavior of Sc{sub 3}@C{sub 82} resembles that for La@C{sub 82} and Y@C{sub 82}, indicating that the identity of the metal does not influence dramatically the energies of the metallofullerene molecular orbitals. The three Sc atoms, however, transfer more electrons from the encapsulated metals to the cage than the monometallic counterparts, accounting for the differences in the voltammetry for Sc{sub 3}@C{sub 82}. The similarity of the voltammetry of Sc{sub 3}@C{sub 82} with that of the monometallic fullerenes suggests that Sc{sub 3}{sup +4}@C{sub 82}{sup 4-} may describe the formal charges on the Sc trimer and the C{sub 82} cage of these species. Metallofullerene electronic structure and physical properties should be better understood as more metallofullerenes become available for investigation. 31 refs., 1 fig., 1 tab.

  7. AGN feedback on the ISM of 3C 236

    NASA Astrophysics Data System (ADS)

    Labiano, A.; García-Burillo, S.; Combes, F.; Usero, A.; Soria-Ruiz, R.; Tremblay, G.; Neri, R.; Fuente, A.; Morganti, R.; Oosterloo, T.

    2013-03-01

    We have carried out 1mm/3mm continuum and 12CO(2-1) line high resolution observations to identify the footprints of AGN feedback on 3C 236. The CO emission comes from a spatially resolved disk characterized by a regular rotating pattern. Within the limits imposed by the sensitivity and velocity coverage of our data, we do not detect any outflow signatures in the cold molecular gas. Re-inspection of optical and IR spectra, shows the presence of a previously unknown ionized gas outflow. The star-formation efficiency in 3C 236, is consistent with the value measured in normal galaxies, which follow the canonical Kennicutt-Schmidt law. This result, confirmed to hold in other young radio sources examined in this work, is in stark contrast with the factor of 10-50 lower SFE that has been claimed to characterize evolved powerful radio galaxies. The recent reactivation of the AGN in 3C 236 is a likely explanation for the early evolutionary status of its molecular disk.

  8. The milliarcsecond structure of 3C 273 at 22 GHz

    SciTech Connect

    Zensus, J.A.; Biretta, J.A.; Unwin, S.C.; Cohen, M.H. Owens Valley Radio Observatory, Pasadena, CA )

    1990-12-01

    The first VLBI images at 22 GHz of the jet in the quasar 3C 273 are presented. In addition to the compact core region, two emission regions can be identified with features seen at lower frequencies; they separate from the core with constant speeds of 0.65 + or - 0.09 and 0.92 + or - 0.11 mas/yr, corresponding to apparent superluminal motion of 4.3 + or - 0.3c and 6.1 + or - 0.3c (for Ho = 100 km/s Mpc, qo = 0.5). The core region brightened at about the estimated epoch of zero separation for the latest superluminal component, suggesting a causal relationship. The curved ridge line of the jet smoothly extends inward towards the core, although no pronounced bends in the range of core distance 0.5-2.5 mas are seen. No significant evidence is found against a common path of subsequent superluminal features. An apparent frequency dependence in the position of one superluminal feature tentatively suggests that opacity effects across the jet direction are present. The results are consistent with an interpretation of the superluminal features as shocks in an underlying relativistic flow, although alternative explanations cannot be ruled out. 43 refs.

  9. The Trails of Superluminal Jet Components in 3C 111

    NASA Technical Reports Server (NTRS)

    Kadler, M.; Ros, E.; Perucho, M.; Kovalev, Y. Y.; Homan, D. C.; Agudo, I.; Kellermann, K. I.; Aller, M. F.; Aller, H. D.; Lister, M. L.; Zensus, J. A.

    2007-01-01

    The parsec-scale radio jet of the broad-line radio galaxy 3C 111 has been monitored since 1995 as part of the 2cm Survey and MOJAVE monitoring observations conducted with the VLBA. Here, we present results from 18 epochs of VLBA observations of 3C 111 and from 18 years of radio flux density monitoring observations conducted at the University of Michigan. A major radio flux-density outburst of 3C 111 occurred in 1996 and was followed by a particularly bright plasma ejection associated with a superluminal jet component. This major event allows us to study a variety of processes associated with outbursts of radio-loud AGN in much greater detail than possible in other cases: the primary perturbation gives rise to the formation of a forward and a backward-shock, which both evolve in characteristically different ways and allow us to draw conclusions about the workflow of jet-production events; the expansion, acceleration and recollimation of the ejected jet plasma in an environment with steep pressure and density gradients are revealed; trailing components are formed in the wake of the primary perturbation as a result of Kelvin- Helmholtz instabilities from the interaction of the jet with the external medium. The jet-medium interaction is further scrutinized by the linear-polarization signature of jet components traveling along the jet and passing a region of steep pressure/density gradients.

  10. Seismic activity in the Transantarctic Mountains recorded by the TAMSEIS seismic array.

    NASA Astrophysics Data System (ADS)

    Anandakrishnan, S.; Stapley, N.; Lawrence, J. F.; Winberry, J. P.; Shore, P. J.; Voigt, D. E.; Wiens, D.; Nyblade, A.

    2004-12-01

    To investigate the links between glaciation and tectonics, we conducted a large-scale seismic deployment in Antarctica that measured local and regional seismicity of both the glaciated terrain of East Antarctica and the non-glaciated Transantarctic Mountains (TAM). The TAM are hypothesized to have formed by rift-flank uplift of the southwestern margin of the West Antarctic Rift System. Active extension of this rift and/or continued uplift of the TAM would likely result in relatively high levels of seismicity along the mountain front. In addition to seismicity from tectonic activity, we suggest that the flow of glaciers, particularly where they accelerate through the TAM, could result in glacier-induced seismicity. We recorded relatively high levels of local seismicity in the TAM. The majority of the seismicity was close to and slightly west of the TAM, beneath the East Antarctic Ice Sheet. We used the double-difference hypocenter location method (Waldhauser and Ellsworth, 2000; Waldhauser 2001) to better image clusters of events. Many of the events are shallow and cluster beneath the David Glacier (which leads to the Drygalski Ice Tongue) and the Darwin Glacier. We suggest that these events are due to fracture at the base of the glaciers, as they steepen towards the coast. We continue to investigate the possibility of surface crevassing and TAM uplift-induced seismicity (along faults which the glaciers have exploited) as the cause of the seismicity.

  11. Jet-induced star formation in 3C 285 and Minkowski's Object

    NASA Astrophysics Data System (ADS)

    Salomé, Q.; Salomé, P.; Combes, F.

    2015-02-01

    How efficiently star formation proceeds in galaxies is still an open question. Recent studies suggest that active galactic nucleus (AGN) can regulate the gas accretion and thus slow down star formation (negative feedback). However, evidence of AGN positive feedback has also been observed in a few radio galaxies (e.g. Centaurus A, Minkowski's Object, 3C 285, and the higher redshift 4C 41.17). Here we present CO observations of 3C 285 and Minkowski's Object, which are examples of jet-induced star formation. A spot (named 3C 285/09.6 in the present paper) aligned with the 3C 285 radio jet at a projected distance of ~70 kpc from the galaxy centre shows star formation that is detected in optical emission. Minkowski's Object is located along the jet of NGC 541 and also shows star formation. Knowing the distribution of molecular gas along the jets is a way to study the physical processes at play in the AGN interaction with the intergalactic medium. We observed CO lines in 3C 285, NGC 541, 3C 285/09.6, and Minkowski's Object with the IRAM 30 m telescope. In the central galaxies, the spectra present a double-horn profile, typical of a rotation pattern, from which we are able to estimate the molecular gas density profile of the galaxy. The molecular gas appears to be in a compact reservoir, which could be evidence of an early phase of the gas accretion after a recent merger event in 3C 285. No kinematic signature of a molecular outflow is detected by the 30 m telescope. Interestingly, 3C 285/09.6 and Minkowski's Object are not detected in CO. The cold gas mass upper limits are consistent with a star formation induced by the compression of dense ambient material by the jet. The depletion time scales in 3C 285/09.6 and Minkowski's Object are of the order of and even shorter than what is found in 3C 285, NGC 541, and local spiral galaxies (109 yr). The upper limit of the molecular gas surface density in 3C 285/09.6 at least follows a Schmidt-Kennicutt law if the emitting region

  12. The lunar seismic tomography and internal heterogeneity

    NASA Astrophysics Data System (ADS)

    Zhao, N.; Zhu, P.; Yuan, Y.; Zhang, J.

    2012-12-01

    A seismic tomography is presented to show the internal lateral heterogeneities of moon. The lunar seismic tomography is made from the moonquake arrival-time data acquired by the Apollo program during 1971 to 1977. The seismic records obtained from the four seismic station of Apollo Lunar Surface Experiments Package on the moon. The research target covers the surround of Apollo-12, 14, 15 and 16 landing sites. A preliminary image of three-dimensional P- and S-wave velocity structures of lunar interior have been calculated using hundreds of arrival-times of moonquake events from surface to deep mantle. These results show that some evidences of lateral heterogeneities in the lunar mantle and crust, which implies the existence of complex structure inside the moon.

  13. Comparative study of 3C-SiC layers sublimation-grown on a 6H-SiC substrate

    SciTech Connect

    Shustov, D. B.; Lebedev, A. A. Lebedev, S. P.; Nelson, D. K.; Sitnikova, A. A.; Zamoryanskaya, M. V.

    2013-09-15

    n-3C-SiC/n-6H-SiC heterostructures grown by vacuum sublimation on CREE commercial 6H-SiC substrates are studied. Transmission electron microscopy (TEM) demonstrated that a transitional layer of varying thickness, composed of a mixture of 3C- and 6H-SiC polytypes, is formed on the substrate. A 3C polytype layer was obtained on the interlayer. Cathodoluminescence study of the surface of the film demonstrated that defects in the form of inclusions of another phase (6H-polytype), stacking faults, and twin boundaries (separating domains of cubic modification, grown in various orientations) are found on the surface and in the surface layer with a thickness on the order of 100 {mu}m. Varying the growth conditions changes the concentration of various types of defects.

  14. Determining the microseismic event source parameters from the surface seismic array data with strong correlated noise and complex focal mechanisms of the source

    NASA Astrophysics Data System (ADS)

    Kushnir, A. F.; Varypaev, A. V.; Rozhkov, M. V.; Epiphansky, A. G.; Dricker, I.

    2014-05-01

    The world experience shows that hydraulic fracturing (fracking) is an efficient tool for increasing oil and gas production of low-permeable reservoirs in hydrocarbon fields. The fracking-induced fractures in the rock, which are hydrodynamically connected with the wells, significantly enhance the volumes of extracted hydrocarbons. Controlling the processes of fracture formation and propagation is a vital question in the oil and gas reservoir management. A key means to implement this control is provided by microseismic monitoring of fracking, which makes it possible to promptly reconstruct the geometry of the fractures from the data on seismic waves from the microearthquakes induced by the formation and propagation of fractures.

  15. Assimilatory Sulfate Reduction in C3, C3-C4, and C4 Species of Flaveria1

    PubMed Central

    Koprivova, Anna; Melzer, Michael; von Ballmoos, Peter; Mandel, Therese; Brunold, Christian; Kopriva, Stanislav

    2001-01-01

    The activity of the enzymes catalyzing the first two steps of sulfate assimilation, ATP sulfurylase and adenosine 5′-phosphosulfate reductase (APR), are confined to bundle sheath cells in several C4 monocot species. With the aim to analyze the molecular basis of this distribution and to determine whether it was a prerequisite or a consequence of the C4 photosynthetic mechanism, we compared the intercellular distribution of the activity and the mRNA of APR in C3, C3-C4, C4-like, and C4 species of the dicot genus Flaveria. Measurements of APR activity, mRNA level, and protein accumulation in six Flaveria species revealed that APR activity, cysteine, and glutathione levels were significantly higher in C4-like and C4 species than in C3 and C3-C4 species. ATP sulfurylase and APR mRNA were present at comparable levels in both mesophyll and bundle sheath cells of C4 species Flaveria trinervia. Immunogold electron microscopy demonstrated the presence of APR protein in chloroplasts of both cell types. These findings, taken together with results from the literature, show that the localization of assimilatory sulfate reduction in the bundle sheath cells is not ubiquitous among C4 plants and therefore is neither a prerequisite nor a consequence of C4 photosynthesis. PMID:11598228

  16. Exploring hydrocarbon-bearing shale formations with multi-component seismic technology and evaluating direct shear modes produced by vertical-force sources

    NASA Astrophysics Data System (ADS)

    Alkan, Engin

    It is essential to understand natural fracture systems embedded in shale-gas reservoirs and the stress fields that influence how induced fractures form in targeted shale units. Multicomponent seismic technology and elastic seismic stratigraphy allow geologic formations to be better images through analysis of different S-wave modes as well as the P-wave mode. Significant amounts of energy produced by P-wave sources radiate through the Earth as downgoing SV-wave energy. A vertical-force source is an effective source for direct SV radiation and provides a pure shear-wave mode (SV-SV) that should reveal crucial information about geologic surfaces located in anisotropic media. SV-SV shear wave modes should carry important information about petrophysical characteristics of hydrocarbon systems that cannot be obtained using other elastic-wave modes. Regardless of the difficulties of extracting good-quality SV-SV signal, direct shear waves as well as direct P and converted S energy should be accounted for in 3C seismic studies. Acquisition of full-azimuth seismic data and sampling data at small intervals over long offsets are required for detailed anisotropy analysis. If 3C3D data can be acquired with improved signal-to-noise ratio, more uniform illumination of targets, increased lateral resolution, more accurate amplitude attributes, and better multiple attenuation, such data will have strong interest by the industry. The objectives of this research are: (1) determine the feasibility of extracting direct SV-SV common-mid-point sections from 3-C seismic surveys, (2) improve the exploration for stratigraphic traps by developing systematic relationship between petrophysical properties and combinations of P and S wave modes, (3) create compelling examples illustrating how hydrocarbon-bearing reservoirs in low-permeable rocks (particularly anisotropic shale formations) can be better characterized using different Swave modes (P-SV, SV-SV) in addition to the conventional P

  17. A low-cost cementite (Fe3C) nanocrystal@N-doped graphitic carbon electrocatalyst for efficient oxygen reduction.

    PubMed

    Wu, Tianxing; Zhang, Haimin; Zhang, Xian; Zhang, Yunxia; Zhao, Huijun; Wang, Guozhong

    2015-11-01

    In this work, chitosan whiskers (CWs) were first extracted using low-cost and earth-abundant crab shells as materials by a series of chemical processes, and then assembled into chitosan whisker microspheres (CWMs) via a simple photochemical polymerization approach. Subsequently, a cementite (Fe3C) nanocrystal@N-doped graphitic carbon (Fe3C@NGC) nanocomposite was successfully fabricated by high temperature pyrolysis of CWMs adsorbed with ferric acetylacetonate (Fe(acac)3) at 900 °C. It was found that a suitable growth atmosphere generated inside CWMs during high temperature pyrolysis is critically important to form Fe3C nanocrystal cores, concurrently accompanying a structural transformation from chitosan whiskers to mesoporous graphitic carbon shells with natural nitrogen (N) doping properties, resulting in the formation of a core-shell structure Fe3C@NGC nanocomposite. The resulting samples were evaluated as electrocatalysts for oxygen reduction reaction (ORR). In comparison with sole N-doped graphitic carbon without Fe3C nanocrystals obtained by direct pyrolysis of chitosan whisker microspheres at 900 °C (CWMs-900), Fe3C@NGC showed significantly improved ORR catalytic activity. The tolerance to fuel cell molecules (e.g., methanol) and the durability of Fe3C@NGC are obviously superior to commercial Pt/C catalysts in alkaline media. The high ORR performance of Fe3C@NGC could be due to its large surface area (313.7 m(2) g(-1)), a synergistic role of Fe3C nanocrystals, N doping in graphitic carbon creating more catalytic active sites, and a porous structure of the nanocomposite facilitating mass transfer to efficiently improve the utilization of these catalytic active sites.

  18. A low-cost cementite (Fe3C) nanocrystal@N-doped graphitic carbon electrocatalyst for efficient oxygen reduction.

    PubMed

    Wu, Tianxing; Zhang, Haimin; Zhang, Xian; Zhang, Yunxia; Zhao, Huijun; Wang, Guozhong

    2015-11-01

    In this work, chitosan whiskers (CWs) were first extracted using low-cost and earth-abundant crab shells as materials by a series of chemical processes, and then assembled into chitosan whisker microspheres (CWMs) via a simple photochemical polymerization approach. Subsequently, a cementite (Fe3C) nanocrystal@N-doped graphitic carbon (Fe3C@NGC) nanocomposite was successfully fabricated by high temperature pyrolysis of CWMs adsorbed with ferric acetylacetonate (Fe(acac)3) at 900 °C. It was found that a suitable growth atmosphere generated inside CWMs during high temperature pyrolysis is critically important to form Fe3C nanocrystal cores, concurrently accompanying a structural transformation from chitosan whiskers to mesoporous graphitic carbon shells with natural nitrogen (N) doping properties, resulting in the formation of a core-shell structure Fe3C@NGC nanocomposite. The resulting samples were evaluated as electrocatalysts for oxygen reduction reaction (ORR). In comparison with sole N-doped graphitic carbon without Fe3C nanocrystals obtained by direct pyrolysis of chitosan whisker microspheres at 900 °C (CWMs-900), Fe3C@NGC showed significantly improved ORR catalytic activity. The tolerance to fuel cell molecules (e.g., methanol) and the durability of Fe3C@NGC are obviously superior to commercial Pt/C catalysts in alkaline media. The high ORR performance of Fe3C@NGC could be due to its large surface area (313.7 m(2) g(-1)), a synergistic role of Fe3C nanocrystals, N doping in graphitic carbon creating more catalytic active sites, and a porous structure of the nanocomposite facilitating mass transfer to efficiently improve the utilization of these catalytic active sites. PMID:26426862

  19. SEISMIC ATTENUATION FOR RESERVOIR CHARACTERIZATION

    SciTech Connect

    Joel Walls; M.T. Taner; Naum Derzhi; Gary Mavko; Jack Dvorkin

    2003-12-01

    We have developed and tested technology for a new type of direct hydrocarbon detection. The method uses inelastic rock properties to greatly enhance the sensitivity of surface seismic methods to the presence of oil and gas saturation. These methods include use of energy absorption, dispersion, and attenuation (Q) along with traditional seismic attributes like velocity, impedance, and AVO. Our approach is to combine three elements: (1) a synthesis of the latest rock physics understanding of how rock inelasticity is related to rock type, pore fluid types, and pore microstructure, (2) synthetic seismic modeling that will help identify the relative contributions of scattering and intrinsic inelasticity to apparent Q attributes, and (3) robust algorithms that extract relative wave attenuation attributes from seismic data. This project provides: (1) Additional petrophysical insight from acquired data; (2) Increased understanding of rock and fluid properties; (3) New techniques to measure reservoir properties that are not currently available; and (4) Provide tools to more accurately describe the reservoir and predict oil location and volumes. These methodologies will improve the industry's ability to predict and quantify oil and gas saturation distribution, and to apply this information through geologic models to enhance reservoir simulation. We have applied for two separate patents relating to work that was completed as part of this project.

  20. Seismicity of California's north coast

    USGS Publications Warehouse

    Bakun, W.H.

    2000-01-01

    At least three moment magnitude (M) 7 earthquakes occurred along California's north coast in the second half of the nineteenth century. The M 7.3 earthquake on 23 November 1873 occurred near the California-Oregon coast and likely was located on the Cascadia subduction zone or within the North American plate. The M 7.0 + earthquake on 9 May 1878 was located about 75 km offshore near the Mendocino fault. The surface-wave magnitude (M(s)) 7.0 earthquake on 16 April 1899 was located about 150 km offshore within the Gorda plate. There were at least three M 7 north-coast earthquakes in the 35 years before 1906, two M 7 earthquakes in the 20 years after 1906, no M 7 earthquakes from 1923 until 1980, and four M 7 earthquakes since 1980. The relative seismic quiescence after 1906 for M 7 earthquakes along California's north coast mimics the post-1906 seismic quiescence in the San Francisco Bay area for M 6 earthquakes. The post-1906 relative quiescence did not extend to lower magnitudes in either area. The 18 April 1906 earthquake apparently influenced the rate of occurrence of M 7 north-coast earthquakes as it apparently influenced the rate of M 6 earthquakes in the San Francisco Bay area. The relative seismic quiescence along the California north-coast region after 1906 should be taken into account when evaluating seismic hazards in northwest California.

  1. Tornado Detection Based on Seismic Signal.

    NASA Astrophysics Data System (ADS)

    Tatom, Frank B.; Knupp, Kevin R.; Vitton, Stanley J.

    1995-02-01

    At the present time the only generally accepted method for detecting when a tornado is on the ground is human observation. Based on theoretical considerations combined with eyewitness testimony, there is strong reason to believe that a tornado in contact with the ground transfers a significant amount of energy into the ground. The amount of energy transferred depends upon the intensity of the tornado and the characteristics of the surface. Some portion of this energy takes the form of seismic waves, both body and surface waves. Surface waves (Rayleigh and possibly Love) represent the most likely type of seismic signal to be detected. Based on the existence of such a signal, a seismic tornado detector appears conceptually possible. The major concerns for designing such a detector are range of detection and discrimination between the tornadic signal and other types of surface waves generated by ground transportation equipment, high winds, or other nontornadic sources.

  2. Analysis of the ambient seismic noise at Bulgarian seismic stations

    NASA Astrophysics Data System (ADS)

    Dimitrova, Liliya; Nikolova, Svetlana

    2010-05-01

    Modernization of Bulgarian National Seismological Network has been performed during a month in 2005. Broadband seismometers and 24-bits digital acquisition systems with dynamic range more than 132dB type DAS130-01 produced by RefTek Inc. were installed at the seismic stations from the existing analog network. In the present study the ambient seismic noise at Bulgarian National Digital Seismological Network (BNDSN) stations is evaluated. In order to compare the performance of the network against international standards the detail analysis of the seismic noise was performed using software and models that are applied in the international practice. The method of McNamara and Bulland was applied and the software code PDFSA was used to determine power spectral density function (PSD) of the background noise and to evaluate the probability density function (PDF). The levels of the ambient seismic noise were determined and the full range of the factors influencing the quality of the data and the performance of a seismic station was analyzed. The estimated PSD functions were compared against two models for high (NHNM) and low (NLNM) noise that are widely used in seismological practice for seismic station monitoring qualities assessment. The mode PDF are used to prepare annual, seasonal, diurnal and frequency analyses of the noise levels at BNDSN stations. The annual analysis shows that the noise levels at the Northern Bulgarian stations are higher than the ones at Central and Southern stations for the microseisms' periods (1sec -7sec). It is well observable at SS PRV and PSN located near Black sea. This is due to the different geological conditions of the seismic stations as well. For the periods of "cultural" noise the power distribution depends on the type of noise sources and as a rule is related to human activities at or near the Earth surface. Seismic stations MPE, VTS and MMB have least mode noise levels and the noisiest stations are PGB, PVL и JMB. The seasonal

  3. The optical variability of the quasar 3C 446

    SciTech Connect

    Barbieri, C.; Vio, R.; Cappellaro, E; Turatto, M Padova Osservatorio Astronomico, Padua )

    1990-08-01

    The optical variability of the quasar 3C 446 is investigated using power spectrum and structure function analysis along with a new set of observations that extend the available data till 1989. No contradiction is found between the PS and SF analyses. The presence of the 1540-day periodicity is strengthened by the occurrence of the 1988 luminosity peak, suggesting that the next burst will occur in the northern spring of 1992. The time series of the quasar is nonstationary. The light variations are determined by a sequence of luminosity bursts, mostly regularly spaced in time and lasting up to 2 yr. 25 refs.

  4. SUZAKU OBSERVATION OF THE GIANT RADIO GALAXY 3C 326

    SciTech Connect

    Isobe, Naoki; Tashiro, Makoto S.; Seta, Hiromi; Gandhi, Poshak; Hayato, Asami; Nagai, Hiroshi; Hada, Kazuhiro; Matsuta, Keiko

    2009-11-20

    A Suzaku observation of a giant radio galaxy, 3C 326, which has a physical size of about 2 Mpc, was conducted on 2008 January 19-21. In addition to several X-ray sources, diffuse emission was significantly detected and associated with its west lobe, but the east lobe was contaminated by an unidentified X-ray source WARP J1552.4+2007. After careful evaluation of the X-ray and non-X-ray background, the 0.4-7 keV X-ray spectrum of the west lobe is described by a power-law model modified with the Galactic absorption. The photon index and 1 keV flux density were derived as GAMMA = 1.82{sup +0.26}{sub -0.24} +- 0.04 and S {sub X} = 19.4{sup +3.3}{sub -3.2} +- 3.0 nJy, respectively, where the first and second errors represent the statistical and systematic ones. The diffuse X-rays were attributed to be inverse Compton (IC) radiation by the synchrotron radio electrons scattering off the cosmic microwave background photons. This radio galaxy is the largest among those with lobes detected through IC X-ray emission. A comparison of the radio to X-ray fluxes yields the energy densities of electron and magnetic field as u{sub e} = (2.3 +- 0.3 +- 0.3) x 10{sup -13} erg cm{sup -3} and u{sub m} = (1.2{sup +0.2}{sub -0.1} +- 0.2) x 10{sup -14} erg cm{sup -3}, respectively. The galaxy is suggested to host a low-luminosity nucleus with an absorption-corrected 2-10 keV luminosity of <2 x 10{sup 42} erg s{sup -1}, together with a relatively weak radio core. The energetics in the west lobe of 3C 326 were compared with those of moderate radio galaxies with a size of approx100 kpc. The west lobe of 3C 326 is confirmed to agree with the correlations for the moderate radio galaxies, u{sub e} propor to D {sup -2.2+}-{sup 0.4} and u{sub m} propor to D {sup -2.4+}-{sup 0.4}, where D is their total physical size. This implies that the lobes of 3C 326 are still being energized by the jet, despite the current weakness of the nuclear activity.

  5. Seismic Noise Analysis and Reduction through Utilization of Collocated Seismic and Atmospheric Sensors at the GRO Chile Seismic Network

    NASA Astrophysics Data System (ADS)

    Farrell, M. E.; Russo, R. M.

    2013-12-01

    The installation of Earthscope Transportable Array-style geophysical observatories in Chile expands open data seismic recording capabilities in the southern hemisphere by nearly 30%, and has nearly tripled the number of seismic stations providing freely-available data in southern South America. Through the use of collocated seismic and atmospheric sensors at these stations we are able to analyze how local atmospheric conditions generate seismic noise, which can degrade data in seismic frequency bands at stations in the ';roaring forties' (S latitudes). Seismic vaults that are climate-controlled and insulated from the local environment are now employed throughout the world in an attempt to isolate seismometers from as many noise sources as possible. However, this is an expensive solution that is neither practical nor possible for all seismic deployments; and also, the increasing number and scope of temporary seismic deployments has resulted in the collection and archiving of terabytes of seismic data that is affected to some degree by natural seismic noise sources such as wind and atmospheric pressure changes. Changing air pressure can result in a depression and subsequent rebound of Earth's surface - which generates low frequency noise in seismic frequency bands - and even moderate winds can apply enough force to ground-coupled structures or to the surface above the seismometers themselves, resulting in significant noise. The 10 stations of the permanent Geophysical Reporting Observatories (GRO Chile), jointly installed during 2011-12 by IRIS and the Chilean Servicio Sismológico, include instrumentation in addition to the standard three seismic components. These stations, spaced approximately 300 km apart along the length of the country, continuously record a variety of atmospheric data including infrasound, air pressure, wind speed, and wind direction. The collocated seismic and atmospheric sensors at each station allow us to analyze both datasets together, to

  6. Geological mounds and their seismic expression

    SciTech Connect

    Swarbrick, R.E. )

    1991-03-01

    Mound geometry (convex upward structure developed above a subhorizontal surface) is common in many geological environments and frequently observed in 2-dimensions on seismic sections. Seismic mounds are typically associated with deep-water clastic sediments, e.g. submarine fans and slumps, and with a variety of carbonate depositional settings, e.g., reefs and banks, but also exist in other depositional settings. Recognition will be dependent on mound dimension, velocity contrast, amplitude strength, and the resolution of the seismic data. Since mounds can represent an important exploration target and recognition of porous, hydrocarbon-bearing section is all-important, careful restitution of the original depositional morphology from the seismic data is required. Details of present velocity distribution are critical, along with a realistic concept of any post-depositional modification, such as compaction, which may have taken place during burial. Where differential compaction is taking place, for example between sand and shale, seismic expression of morphology will be continually modified during progressive burial. Analysis of structure at the top and base of the mound can provide support for lithological interpretation based on other criteria, such as seismic facies analysis based on internal and external reflections. Modeling, using parameters from mounds in a variety of known depositional settings, illustrates many of the interpretational problems associated with seismic mounds and provides some objective criteria for analysis of mound morphology. Comparison is made with real data, principally from northwest Europe and North America.

  7. Moon meteoritic seismic hum: Steady state prediction

    USGS Publications Warehouse

    Lognonne, P.; Feuvre, M.L.; Johnson, C.L.; Weber, R.C.

    2009-01-01

    We use three different statistical models describing the frequency of meteoroid impacts on Earth to estimate the seismic background noise due to impacts on the lunar surface. Because of diffraction, seismic events on the Moon are typically characterized by long codas, lasting 1 h or more. We find that the small but frequent impacts generate seismic signals whose codas overlap in time, resulting in a permanent seismic noise that we term the "lunar hum" by analogy with the Earth's continuous seismic background seismic hum. We find that the Apollo era impact detection rates and amplitudes are well explained by a model that parameterizes (1) the net seismic impulse due to the impactor and resulting ejecta and (2) the effects of diffraction and attenuation. The formulation permits the calculation of a composite waveform at any point on the Moon due to simulated impacts at any epicentral distance. The root-mean-square amplitude of this waveform yields a background noise level that is about 100 times lower than the resolution of the Apollo long-period seismometers. At 2 s periods, this noise level is more than 1000 times lower than the low noise model prediction for Earth's microseismic noise. Sufficiently sensitive seismometers will allow the future detection of several impacts per day at body wave frequencies. Copyright 2009 by the American Geophysical Union.

  8. Engineering Seismic Base Layer for Defining Design Earthquake Motion

    SciTech Connect

    Yoshida, Nozomu

    2008-07-08

    Engineer's common sense that incident wave is common in a widespread area at the engineering seismic base layer is shown not to be correct. An exhibiting example is first shown, which indicates that earthquake motion at the ground surface evaluated by the analysis considering the ground from a seismic bedrock to a ground surface simultaneously (continuous analysis) is different from the one by the analysis in which the ground is separated at the engineering seismic base layer and analyzed separately (separate analysis). The reason is investigated by several approaches. Investigation based on eigen value problem indicates that the first predominant period in the continuous analysis cannot be found in the separate analysis, and predominant period at higher order does not match in the upper and lower ground in the separate analysis. The earthquake response analysis indicates that reflected wave at the engineering seismic base layer is not zero, which indicates that conventional engineering seismic base layer does not work as expected by the term 'base'. All these results indicate that wave that goes down to the deep depths after reflecting in the surface layer and again reflects at the seismic bedrock cannot be neglected in evaluating the response at the ground surface. In other words, interaction between the surface layer and/or layers between seismic bedrock and engineering seismic base layer cannot be neglected in evaluating the earthquake motion at the ground surface.

  9. Advanced Seismic While Drilling System

    SciTech Connect

    Robert Radtke; John Fontenot; David Glowka; Robert Stokes; Jeffery Sutherland; Ron Evans; Jim Musser

    2008-06-30

    . An APS Turbine Alternator powered the SeismicPULSER{trademark} to produce two Hz frequency peak signals repeated every 20 seconds. Since the ION Geophysical, Inc. (ION) seismic survey surface recording system was designed to detect a minimum downhole signal of three Hz, successful performance was confirmed with a 5.3 Hz recording with the pumps running. The two Hz signal generated by the sparker was modulated with the 3.3 Hz signal produced by the mud pumps to create an intense 5.3 Hz peak frequency signal. The low frequency sparker source is ultimately capable of generating selectable peak frequencies of 1 to 40 Hz with high-frequency spectra content to 10 kHz. The lower frequencies and, perhaps, low-frequency sweeps, are needed to achieve sufficient range and resolution for realtime imaging in deep (15,000 ft+), high-temperature (150 C) wells for (a) geosteering, (b) accurate seismic hole depth, (c) accurate pore pressure determinations ahead of the bit, (d) near wellbore diagnostics with a downhole receiver and wired drill pipe, and (e) reservoir model verification. Furthermore, the pressure of the sparker bubble will disintegrate rock resulting in an increased overall rates of penetration. Other applications for the SeismicPULSER{trademark} technology are to deploy a low-frequency source for greater range on a wireline for Reverse Vertical Seismic Profiling (RVSP) and Cross-Well Tomography. Commercialization of the technology is being undertaken by first contacting stakeholders to define the value proposition for rig site services utilizing SeismicPULSER{trademark} technologies. Stakeholders include national oil companies, independent oil companies, independents, service companies, and commercial investors. Service companies will introduce a new Drill Bit SWD service for deep HTHP wells. Collaboration will be encouraged between stakeholders in the form of joint industry projects to develop prototype tools and initial field trials. No barriers have been identified

  10. Expanding Conventional Seismic Stratigrphy into the Multicomponent Seismic Domain

    SciTech Connect

    Innocent Aluka

    2008-08-31

    Multicomponent seismic data are composed of three independent vector-based seismic wave modes. These wave modes are, compressional mode (P), and shear modes SV and SH. The three modes are generated using three orthogonal source-displacement vectors and then recorded using three orthogonal vector sensors. The components travel through the earth at differing velocities and directions. The velocities of SH and SV as they travel through the subsurface differ by only a few percent, but the velocities of SV and SH (Vs) are appreciably lower than the P-wave velocity (Vp). The velocity ratio Vp/Vs varies by an order of magnitude in the earth from a value of 15 to 1.5 depending on the degree of sedimentary lithification. The data used in this study were acquired by nine-component (9C) vertical seismic profile (VSP), using three orthogonal vector sources. The 9C vertical seismic profile is capable of generating P-wave mode and the fundamental S-wave mode (SH-SH and SV-SV) directly at the source station and permits the basic components of elastic wavefield (P, SH-SH and SV-SV) to be separated from one another for the purposes of imaging. Analysis and interpretations of data from the study area show that incident full-elastic seismic wavefield is capable of reflecting four different wave modes, P, SH , SV and C which can be utilized to fully understand the architecture and heterogeneities of geologic sequences. The conventional seismic stratigraphy utilizes only reflected P-wave modes. The notation SH mode is the same as SH-SH; SV mode means SV-SV and C mode which is a converted shear wave is a special SV mode and is the same as P-SV. These four wave modes image unique geologic stratigraphy and facies and at the same time reflect independent stratal surfaces because of the unique orientation of their particle-displacement vectors. As a result of the distinct orientation of individual mode's particle-displacement vector, one mode may react to a critical subsurface sequence more

  11. Multiwavelength variability analysis of the FSRQ 3C 279

    NASA Astrophysics Data System (ADS)

    Patiño-Álvarez, V.; Chavushyan, V.; León-Tavares, J.; Carramiñana, A.; Carrasco, L.; Fernandes, S.; Schlegel, E. M.; López-Rodríguez, E.

    2015-03-01

    We present a multifrequency analysis of the variability in the flat-spectrum radio quasar 3C 279 from 2008 to 2014. Our multiwavelength dataset includes gamma-ray data from Fermi/LAT (Abdo et al. 2009), observations in 1mm from SMA (Gurwell et al. 2007), Near Infrared from OAGH (Carramiñana & Carrasco 2009) and SMARTS (Bonning et al. 2012); optical V band from the Steward Observatory (Smith et al. 2009) and SMARTS; optical spectra from OAGH (Patiño-Álvarez et al. 2013) and the Steward Observatory; and polarization spectra from the Steward Observatory. The light curves are shown in Fig. 1. Six out of seven optical activity periods identified within our dataset show clear counterparts in mm, NIR and gamma-rays, however, the late 2011 - early 2012 optical flare does not have a counterpart in the GeV regime. In this contribution, we discuss the flaring evolution of 3C 279 and speculate about the production of the anomalous activity period.

  12. Shocked Molecular Gas in the SNR 3C391

    NASA Astrophysics Data System (ADS)

    Bock, D. C.-J.; Wright, M. C. H.; Frail, D. A.; Gaensler, B. M.; Wilner, D. J.

    1999-05-01

    The discovery of OH (1720 MHz) masers in supernova remnants (SNRs) provides us with a convenient method for identifying promising candidates for studies of SNR/molecular cloud interactions. One remnant which is an ideal subject is 3C391. Here, single dish observations reveal a myriad of molecular lines from a giant shocked cloud at the blast-wave of the remnant. We present recent millimeter-wave observations of 3C391 with the Berkeley-Illinois-Maryland Association (BIMA) array. We have imaged the region towards the OH maser in HCN (J=1--0) and HCO+ (J=1--0) at a resolution of 4 arcsec. The morphology and brightness of the emission in HCO+ and HCN are similar; we resolve the shocked cloud seen by Frail and Mitchell (1998) into several clumps of characteristic size 10 arcsec. The maser is midway between two of these clumps, rather than being coincident with the peak column density. The clumps all have similar spectra with line-widths of ~ 30 km s(-1) , although there is evidence for a velocity gradient between the clumps. We examine the physical conditions of the shocked environment and discuss the relative abundances of the molecules. A companion study of the interaction between the SNR W51C and an associated molecular cloud is underway.

  13. Angola Seismicity MAP

    NASA Astrophysics Data System (ADS)

    Neto, F. A. P.; Franca, G.

    2014-12-01

    The purpose of this job was to study and document the Angola natural seismicity, establishment of the first database seismic data to facilitate consultation and search for information on seismic activity in the country. The study was conducted based on query reports produced by National Institute of Meteorology and Geophysics (INAMET) 1968 to 2014 with emphasis to the work presented by Moreira (1968), that defined six seismogenic zones from macro seismic data, with highlighting is Zone of Sá da Bandeira (Lubango)-Chibemba-Oncócua-Iona. This is the most important of Angola seismic zone, covering the epicentral Quihita and Iona regions, geologically characterized by transcontinental structure tectono-magmatic activation of the Mesozoic with the installation of a wide variety of intrusive rocks of ultrabasic-alkaline composition, basic and alkaline, kimberlites and carbonatites, strongly marked by intense tectonism, presenting with several faults and fractures (locally called corredor de Lucapa). The earthquake of May 9, 1948 reached intensity VI on the Mercalli-Sieberg scale (MCS) in the locality of Quihita, and seismic active of Iona January 15, 1964, the main shock hit the grade VI-VII. Although not having significant seismicity rate can not be neglected, the other five zone are: Cassongue-Ganda-Massano de Amorim; Lola-Quilengues-Caluquembe; Gago Coutinho-zone; Cuima-Cachingues-Cambândua; The Upper Zambezi zone. We also analyzed technical reports on the seismicity of the middle Kwanza produced by Hidroproekt (GAMEK) region as well as international seismic bulletins of the International Seismological Centre (ISC), United States Geological Survey (USGS), and these data served for instrumental location of the epicenters. All compiled information made possible the creation of the First datbase of seismic data for Angola, preparing the map of seismicity with the reconfirmation of the main seismic zones defined by Moreira (1968) and the identification of a new seismic

  14. Large scale mechanical metamaterials as seismic shields

    NASA Astrophysics Data System (ADS)

    Miniaci, Marco; Krushynska, Anastasiia; Bosia, Federico; Pugno, Nicola M.

    2016-08-01

    Earthquakes represent one of the most catastrophic natural events affecting mankind. At present, a universally accepted risk mitigation strategy for seismic events remains to be proposed. Most approaches are based on vibration isolation of structures rather than on the remote shielding of incoming waves. In this work, we propose a novel approach to the problem and discuss the feasibility of a passive isolation strategy for seismic waves based on large-scale mechanical metamaterials, including for the first time numerical analysis of both surface and guided waves, soil dissipation effects, and adopting a full 3D simulations. The study focuses on realistic structures that can be effective in frequency ranges of interest for seismic waves, and optimal design criteria are provided, exploring different metamaterial configurations, combining phononic crystals and locally resonant structures and different ranges of mechanical properties. Dispersion analysis and full-scale 3D transient wave transmission simulations are carried out on finite size systems to assess the seismic wave amplitude attenuation in realistic conditions. Results reveal that both surface and bulk seismic waves can be considerably attenuated, making this strategy viable for the protection of civil structures against seismic risk. The proposed remote shielding approach could open up new perspectives in the field of seismology and in related areas of low-frequency vibration damping or blast protection.

  15. Preclinical evaluation of a monoclonal antibody (3C6) specific for prostate-specific membrane antigen

    PubMed Central

    Regino, C.A.S.; Wong, K.J.; Milenic, D.E.; Holmes, E.H.; Garmestani, K.; Choyke, P.L.; Brechbiel, M.W.

    2008-01-01

    Better tumor markers are needed for early diagnosis and staging of prostate cancer, and for monitoring therapeutic response than the currently used prostate specific antigen (PSA). Prostate specific membrane antigen (PSMA) is highly expressed on the surface of prostatic epithelial cells making it a good target for prostate cancer. In this study, mAb 3C6, specific for the extracellular epitope of PSMA, was evaluated both in vitro and in vivo for PSMA-targeting. Immunoreactivity and specificity of mAb 3C6 was evaluated by flow cytometry using prostate cell lines expressing PSMA such as LNCaP and 22Rv1 and a cell line, DU145, that expresses very little PSMA. 3C6 was conjugated with the acyclic CHX-A” DTPA chelate, radiolabeled with 111In, and its in vitro and in vivo properties were assessed. The biodistribution of the radioimmunoconjugate evaluated in athymic mice bearing xenografts of three human prostate carcinoma cell lines shows high uptake after 72 hr in LNCaP tumors (%ID/g 22.93 ± 6.32) and 22Rv1 (%ID/g 10.44 ± 2.32) in contrast to low uptake by the DU145 tumors (%ID/g 4.27 ± 0.37). Planar γ-scintigraphic images obtained for xenografted tumor bearing mice demonstrated targeting for PSMA positive tumors suggesting possible applications in imaging and for targeted radiation therapy. PMID:20047017

  16. Ni3Mo3C as anode catalyst for high-performance microbial fuel cells.

    PubMed

    Zeng, Li-Zhen; Zhao, Shao-Fei; Li, Wei-Shan

    2015-03-01

    Ni3Mo3C was prepared by a modified organic colloid method and explored as anode catalyst for high-performance microbial fuel cell (MFC) based on Klebsiella pneumoniae (K. pneumoniae). The prepared sample was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and Brunauer-Emmett-Teller (BET). The activity of the sample as anode catalyst for MFC based on K. pneumoniae was investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and polarization curve measurement. The results show that the adding of nickel in Mo2C increases the BET surface area of Mo2C and improves the electrocatalytic activity of Mo2C towards the oxidation of microbial fermentation products. The power density of MFC with 3 mg cm(-2) Ni3Mo3C anode is far higher than that of the MFC with carbon felt as anode without any catalyst, which is 19 % higher than that of Mo2C anode and produced 62 % as much as that of Pt anode, indicating that Ni3Mo3C is comparative to noble metal platinum as anode electrocatalyst for MFCs by increasing the loading.

  17. Carbon Monoxide Observations Toward the Supernova Remnant 3C 391: Interaction Confirmed

    NASA Astrophysics Data System (ADS)

    Wilner, D. J.; Reynolds, S. P.; Moffett, D. A.

    1996-05-01

    We present observations of the J = 1 -> 0 transition of CO toward the radio-bright supernova remnant 3C 391 made with the NRAO 12-m telescope.(*) Our earlier radio continuum observations of 3C 391 showed a morphology strongly suggestive of evolution near a density discontinuity in the external medium. In this interpretation, the supernova went off near the edge of a moderately dense molecular cloud, and after a few hundred to a thousand years the blast wave broke out of the edge of the cloud to emerge as a larger, lower surface-brightness extension to the SNR. Survey data indicated nearby CO at appropriate velocities but direct evidence for interaction was lacking. Our new observations strongly support the interaction picture. CO contours drop steeply at the location of the inner edge of the SNR radio emission; the ``blowout'' extension is in the direction of steepest decrease of CO contours. Extensions on the bright limb of radio continuum perfectly match the edges of a strong CO condensation. A consistent picture then involves the SNR blast wave eating its way into the molecular cloud, destroying CO as it goes. The data also indicate directly that shock acceleration of electrons at least to 10 GeV or so is possible even for a blast wave encountering dense neutral material. We describe the quantitative implications of the interaction picture for 3C 391 and for SNRs in general. (*) The NRAO is operated by Associated Universities, Inc., under a cooperative agreement with the National Science Foundation.

  18. A seismic metamaterial: The resonant metawedge.

    PubMed

    Colombi, Andrea; Colquitt, Daniel; Roux, Philippe; Guenneau, Sebastien; Craster, Richard V

    2016-06-10

    Critical concepts from three different fields, elasticity, plasmonics and metamaterials, are brought together to design a metasurface at the geophysical scale, the resonant metawedge, to control seismic Rayleigh waves. Made of spatially graded vertical subwavelength resonators on an elastic substrate, the metawedge can either mode convert incident surface Rayleigh waves into bulk elastic shear waves or reflect the Rayleigh waves creating a "seismic rainbow" effect analogous to the optical rainbow for electromagnetic metasurfaces. Time-domain spectral element simulations demonstrate the broadband efficacy of the metawedge in mode conversion while an analytical model is developed to accurately describe and predict the seismic rainbow effect; allowing the metawedge to be designed without the need for extensive parametric studies and simulations. The efficiency of the resonant metawedge shows that large-scale mechanical metamaterials are feasible, will have application, and that the time is ripe for considering many optical devices in the seismic and geophysical context.

  19. A seismic metamaterial: The resonant metawedge.

    PubMed

    Colombi, Andrea; Colquitt, Daniel; Roux, Philippe; Guenneau, Sebastien; Craster, Richard V

    2016-01-01

    Critical concepts from three different fields, elasticity, plasmonics and metamaterials, are brought together to design a metasurface at the geophysical scale, the resonant metawedge, to control seismic Rayleigh waves. Made of spatially graded vertical subwavelength resonators on an elastic substrate, the metawedge can either mode convert incident surface Rayleigh waves into bulk elastic shear waves or reflect the Rayleigh waves creating a "seismic rainbow" effect analogous to the optical rainbow for electromagnetic metasurfaces. Time-domain spectral element simulations demonstrate the broadband efficacy of the metawedge in mode conversion while an analytical model is developed to accurately describe and predict the seismic rainbow effect; allowing the metawedge to be designed without the need for extensive parametric studies and simulations. The efficiency of the resonant metawedge shows that large-scale mechanical metamaterials are feasible, will have application, and that the time is ripe for considering many optical devices in the seismic and geophysical context. PMID:27283587

  20. A seismic metamaterial: The resonant metawedge

    NASA Astrophysics Data System (ADS)

    Colombi, Andrea; Colquitt, Daniel; Roux, Philippe; Guenneau, Sebastien; Craster, Richard V.

    2016-06-01

    Critical concepts from three different fields, elasticity, plasmonics and metamaterials, are brought together to design a metasurface at the geophysical scale, the resonant metawedge, to control seismic Rayleigh waves. Made of spatially graded vertical subwavelength resonators on an elastic substrate, the metawedge can either mode convert incident surface Rayleigh waves into bulk elastic shear waves or reflect the Rayleigh waves creating a “seismic rainbow” effect analogous to the optical rainbow for electromagnetic metasurfaces. Time-domain spectral element simulations demonstrate the broadband efficacy of the metawedge in mode conversion while an analytical model is developed to accurately describe and predict the seismic rainbow effect; allowing the metawedge to be designed without the need for extensive parametric studies and simulations. The efficiency of the resonant metawedge shows that large-scale mechanical metamaterials are feasible, will have application, and that the time is ripe for considering many optical devices in the seismic and geophysical context.

  1. A seismic metamaterial: The resonant metawedge

    PubMed Central

    Colombi, Andrea; Colquitt, Daniel; Roux, Philippe; Guenneau, Sebastien; Craster, Richard V.

    2016-01-01

    Critical concepts from three different fields, elasticity, plasmonics and metamaterials, are brought together to design a metasurface at the geophysical scale, the resonant metawedge, to control seismic Rayleigh waves. Made of spatially graded vertical subwavelength resonators on an elastic substrate, the metawedge can either mode convert incident surface Rayleigh waves into bulk elastic shear waves or reflect the Rayleigh waves creating a “seismic rainbow” effect analogous to the optical rainbow for electromagnetic metasurfaces. Time-domain spectral element simulations demonstrate the broadband efficacy of the metawedge in mode conversion while an analytical model is developed to accurately describe and predict the seismic rainbow effect; allowing the metawedge to be designed without the need for extensive parametric studies and simulations. The efficiency of the resonant metawedge shows that large-scale mechanical metamaterials are feasible, will have application, and that the time is ripe for considering many optical devices in the seismic and geophysical context. PMID:27283587

  2. Crystalline Ni3C as both carbon source and catalyst for graphene nucleation: a QM/MD study

    PubMed Central

    Jiao, Menggai; Li, Kai; Guan, Wei; Wang, Ying; Wu, Zhijian; Page, Alister; Morokuma, Keiji

    2015-01-01

    Graphene nucleation from crystalline Ni3C has been investigated using quantum chemical molecular dynamics (QM/MD) simulations based on the self-consistent-charge density-functional tight-binding (SCC-DFTB) method. It was observed that the lattice of Ni3C was quickly relaxed upon thermal annealing at high temperature, resulting in an amorphous Ni3C catalyst structure. With the aid of the mobile nickel atoms, inner layer carbon atoms precipitated rapidly out of the surface and then formed polyyne chains and Y-junctions. The frequent sinusoidal-like vibration of the branched carbon configurations led to the formation of nascent graphene precursors. In light of the rapid decomposition of the crystalline Ni3C, it is proposed that the crystalline Ni3C is unlikely to be a reaction intermediate in the CVD-growth of graphene at high temperatures. However, results present here indicate that Ni3C films can be employed as precursors in the synthesis of graphene with exciting possibility. PMID:26169042

  3. Joint seismic-geodynamic-mineral physical modelling of African geodynamics: A reconciliation of deep-mantle convection with surface geophysical constraints

    SciTech Connect

    Forte, A M; Quere, S; Moucha, R; Simmons, N A; Grand, S P; Mitrovica, J X; Rowley, D B

    2008-08-22

    Recent progress in seismic tomography provides the first complete 3-D images of the combined thermal and chemical anomalies that characterise the unique deep mantle structure below the African continent. With these latest tomography results we predict flow patterns under Africa that reveal a large-scale, active hot upwelling, or superplume, below the western margin of Africa under the Cape Verde Islands. The scale and dynamical intensity of this West African superplume (WASP) is comparable to that of the south African superplume (SASP) that has long been assumed to dominate the flow dynamics under Africa. On the basis of this new tomography model, we find the dynamics of the SASP is strongly controlled by chemical contributions to deep mantle buoyancy that significantly compensate its thermal buoyancy. In contrast, the WASP appears to be entirely dominated by thermal buoyancy. New calculations of mantle convection incorporating these two superplumes reveal that the plate-driving forces due to the flow generated by the WASP is as strong as that due to the SASP. We find that the chemical buoyancy of the SASP exerts a strong stabilising control on the pattern and amplitude of shallow mantle flow in the asthenosphere below the southern half of the African plate. The asthenospheric flow predictions provide the first high resolution maps of focussed upwellings that lie below the major centres of Late Cenozoic volcanism, including the Kenya domes and Hoggar massif that lies above a remnant plume head in the upper mantle. Inferences of sublithospheric deformation from seismic anisotropy data are shown to be sensitive to the contributions of chemical buoyancy in the SASP.

  4. Seismic excitation by space shuttles

    USGS Publications Warehouse

    Kanamori, H.; Mori, J.; Sturtevant, B.; Anderson, D.L.; Heaton, T.

    1992-01-01

    Shock waves generated by the space shuttles Columbia (August 13, 1989), Atlantis (April 11, 1991) and Discovery (September 18, 1991) on their return to Edwards Air Force Base, California, were recorded by TERRAscope (Caltech's broadband seismic network), the Caltech-U.S.G.S Southern California Seismic Network (SCSN), and the University of Southern California (USC) Los Angeles Basin Seismic Network. The spatial pattern of the arrival times exhibits hyperbolic shock fronts from which the path, velocity and altitude of the space shuttle could be determined. The shock wave was acoustically coupled to the ground, converted to a seismic wave, and recorded clearly at the broadband TERRAscope stations. The acoustic coupling occurred very differently depending on the conditions of the Earth's surface surrounding the station. For a seismic station located on hard bedrock, the shock wave (N wave) was clearly recorded with little distortion. Aside from the N wave, very little acoustic coupling of the shock wave energy to the ground occurred at these sites. The observed N wave record was used to estimate the overpressure of the shock wave accurately; a pressure change of 0.5 to 2.2 mbars was obtained. For a seismic station located close to the ocean or soft sedimentary basins, a significant amount of shock wave energy was transferred to the ground through acoustic coupling of the shock wave and the oceanic Rayleigh wave. A distinct topography such as a mountain range was found effective to couple the shock wave energy to the ground. Shock wave energy was also coupled to the ground very effectively through large man made structures such as high rise buildings and offshore oil drilling platforms. For the space shuttle Columbia, in particular, a distinct pulse having a period of about 2 to 3 seconds was observed, 12.5 s before the shock wave, with a broadband seismograph in Pasadena. This pulse was probably excited by the high rise buildings in downtown Los Angeles which were

  5. Downhole Seismic Monitoring at the Geysers

    SciTech Connect

    Rutledge, J.T.; Anderson, T.D.; Fairbanks, T.D.; Albright, J.N.

    1999-10-17

    A 500-ft length, 6-level, 3-component, vertical geophone array was permanently deployed within the upper 800 ft of Unocal's well GDCF 63-29 during a plug and abandonment operation on April 7, 1998. The downhole array remains operational after a period of 1 year, at a temperature of about 150 C. Continuous monitoring and analysis of shallow seismicity (<4000 ft deep) has been conducted over that same 1-year period. The downhole array was supplemented with 4 surface stations in late-1998 and early-1999 to help constrain locations of shallow seismicity. Locations occurring within about 1 km ({approximately}3000 ft) of the array have been determined for a subset of high-frequency events detected on the downhole and surface stations for the 10-week period January 6 to March 16, 1999. These events are distinct from surface-monitored seismicity at The Geysers in that they occur predominantly above the producing reservoir, at depths ranging from about 1200 to 4000 ft depth (1450 to -1350 ft elevation). The shallow seismicity shows a northeast striking trend, similar to seismicity trends mapped deeper within the reservoir and the strike of the predominant surface lineament observed over the productive field.

  6. 17 CFR 270.3c-4 - Definition of “common trust fund” as used in section 3(c)(3) of the Act.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Definition of âcommon trust... 1940 § 270.3c-4 Definition of “common trust fund” as used in section 3(c)(3) of the Act. The term common trust fund as used in section 3(c)(3) of the Act (15 U.S.C. 80a-3(c)(3)) shall include a...

  7. FY-3C/VIRR SST algorithm and cal/val activities at NSMC/CMA

    NASA Astrophysics Data System (ADS)

    Wang, Sujuan; Cui, Peng; Zhang, Peng; Ran, Maonong; Lu, Feng; Wang, Weihe

    2014-11-01

    The National Satellite Meteorological Center (NSMC)/CMA global sea surface temperature (SST) data are derived from measurements made by the Visible and Infrared Radiometer (VIRR) on board the FY-3 series polar orbiting satellites. Quality controlled in situ data from iQUAM (STAR/NESDIS/NOAA) is used in FY-3B/C VIRR matching procedure. The monthly matchup database (MDB) is created from FY-3C VIRR measurements paired with coincident SST measurements from buoys since November 2013. The satellite sensor's brightness temperature and buoy SST pairs are included in the MDB if they are coincident within 3km in space and 1 hour in time. Least-Square Regression is used for estimating the first-guess coefficient and SST residuals. Outliers are removed using Median±2STD, and the final coefficients of robust regression are estimated. A set of SST regression formalisms are tested base on NOAA- 19/AVHRR 2010 MDB. The test shows that, for daytime split-window nonlinear SST (NLSST) is the best, for nighttime triple-window MCSST (TCSST) is the best, which is agree with STAR/NESDIS's. The same regression analysis method also used on FY-3C/VIRR MDB. Compare with the three daytime SST algorithms and five nighttime SST algorithms, the best algorithm to retrieve FY-3C/VIRR SST for daytime is NLSST and for nighttime is TCSST. Compare with the coefficients of nighttime algorithm TCSST, it shows that for FY-3B/C VIRR SST, the contribution of 3.7μm band is smaller than split-window bands. The performance of 3.7μm band of FY-3C/VIRR is better than FY-3B/VIRR, but worse than NOAA-19/AVHRR.

  8. 17 CFR 270.3c-3 - Definition of certain terms used in section 3(c)(1) of the Act with respect to certain debt...

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... investment companies. 270.3c-3 Section 270.3c-3 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) RULES AND REGULATIONS, INVESTMENT COMPANY ACT OF 1940 § 270.3c-3 Definition of certain... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Definition of certain...

  9. Development of potent inhibitors of the coxsackievirus 3C protease

    SciTech Connect

    Lee, Eui Seung; Lee, Won Gil; Yun, Soo-Hyeon; Rho, Seong Hwan; Im, Isak; Yang, Sung Tae; Sellamuthu, Saravanan; Lee, Yong Jae; Kwon, Sun Jae; Park, Ohkmae K.; Jeon, Eun-Seok; Park, Woo Jin . E-mail: wjpark@gist.ac.kr; Kim, Yong-Chul . E-mail: yongchul@gist.ac.kr

    2007-06-22

    Coxsackievirus B3 (CVB3) 3C protease (3CP) plays essential roles in the viral replication cycle, and therefore, provides an attractive therapeutic target for treatment of human diseases caused by CVB3 infection. CVB3 3CP and human rhinovirus (HRV) 3CP have a high degree of amino acid sequence similarity. Comparative modeling of these two 3CPs revealed one prominent distinction; an Asn residue delineating the S2' pocket in HRV 3CP is replaced by a Tyr residue in CVB3 3CP. AG7088, a potent inhibitor of HRV 3CP, was modified by substitution of the ethyl group at the P2' position with various hydrophobic aromatic rings that are predicted to interact preferentially with the Tyr residue in the S2' pocket of CVB3 3CP. The resulting derivatives showed dramatically increased inhibitory activities against CVB3 3CP. In addition, one of the derivatives effectively inhibited the CVB3 proliferation in vitro.

  10. Milliarcsecond polarization structure of the superluminal quasar 3C 273

    NASA Astrophysics Data System (ADS)

    Roberts, David H.; Kollgaard, Ronald I.; Brown, Leslie F.; Gabuzda, Denise C.; Wardle, John F. C.

    1990-09-01

    A 2 x 10 marcsec-resolution determination is presented for the total intensity and linear polarization structures of the superluminal quasar 3C 273 at 5 GHz. Substantial polarized flux was detected from several superluminal components of the jet, whose fractional polarization increased symmetrically with distance from the core; the most distant component is highly polarized and exhibits a highly ordered magnetic field. Within a few marcsec of the core, the inferred magnetic field orientation varies rapidly with position along the jet. The primarily longitudinal magnetic field orientation is concluded to become established within 20 marcsec of the core. A highly disorganized magnetic field is the most plausible explanation for the low degree of polarization in the innermost regions of the jet.

  11. Trisodium citrate, Na3(C6H5O7)

    PubMed Central

    Rammohan, Alagappa; Kaduk, James A.

    2016-01-01

    The crystal structure of anhydrous tris­odium citrate, Na3(C6H5O7), has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional theory (DFT). There are two independent five-coordinate Na+ and one six-coordinate Na+ cations in the asymmetric unit. The [NaO5] and [NaO6] polyhedra share edges and corners to form a three-dimensional framework. There are channels parallel to the a and b axes in which the remainder of the citrate anions reside. The only hydrogen bonds are an intra­molecular one between the hy­droxy group and one of the terminal carboxyl­ate O atoms and an intermolecular one between a methylene group and the hydroxyl O atom. PMID:27308044

  12. Anisotropies in the HI gas distribution toward 3C 196

    NASA Astrophysics Data System (ADS)

    Kalberla, P. M. W.; Kerp, J.

    2016-10-01

    Context. The local Galactic Hi gas was found to contain cold neutral medium (CNM) filaments that are aligned with polarized dust emission. These filaments appear to be dominated by the magnetic field and in this case turbulence is expected to show distinct anisotropies. Aims: We use the Galactic Effelsberg-Bonn Hi Survey (EBHIS) to derive 2D turbulence spectra for the Hi distribution in direction to 3C 196 and two more comparison fields. Methods: Prior to Fourier transform we apply a rotational symmetric 50% Tukey window to apodize the data. We derive average as well as position angle dependent power spectra. Anisotropies in the power distribution are defined as the ratio of the spectral power in orthogonal directions. Results: We find strong anisotropies. For a narrow range in position angle, in direction perpendicular to the filaments and the magnetic field, the spectral power is on average more than an order of magnitude larger than parallel. In the most extreme case the anisotropy reaches locally a factor of 130. Anisotropies increase on average with spatial frequency as predicted by Goldreich & Sridhar (1995, ApJ, 438, 763), at the same time the Kolmogorov spectral index remains almost unchanged. The strongest anisotropies are observable for a narrow range in velocity and decay with a power law index close to -8/3, almost identical to the average isotropic spectral index of -2.9 <γ< -2.6. Conclusions: Hi filaments, associated with linear polarization structures in LOFAR observations in direction to 3C 196, show turbulence spectra with marked anisotropies. Decaying anisotropies appear to indicate that we witness an ongoing shock passing the Hi and affecting the observed Faraday depth.

  13. Source spectra of seismic hum

    NASA Astrophysics Data System (ADS)

    Nishida, Kiwamu

    2014-10-01

    The observation of seismic hum from 2 to 20 mHz, also known as Earth's background free oscillations, has been established. Recent observations by broad-band seismometers show simultaneous excitation of Love waves (fundamental toroidal modes) and Rayleigh waves (fundamental spheroidal modes). The excitation amplitudes above 10 mHz can be explained by random shear traction sources on Earth's surface. With estimated source distributions, the most likely excitation mechanism is a linear coupling between ocean infragravity waves and seismic surface waves through seafloor topography. Observed Love and Rayleigh wave amplitudes below 5 mHz suggest that surface pressure sources could also contribute to their excitations, although the amplitudes have large uncertainties due to the high noise levels of the horizontal components. To quantify the observation, we develop a new method for estimation of the source spectra of random tractions on Earth's surface by modelling cross-spectra between pairs of stations. The method is to calculate synthetic cross-spectra for spatially isotropic and homogeneous excitations by random shear traction and pressure sources, and invert them with the observed cross-spectra to obtain the source spectra. We applied this method to the IRIS, ORFEUS, and F-net records from 618 stations with three components of broad-band seismometers for 2004-2011. The results show the dominance of shear traction above 5 mHz, which is consistent with past studies. Below 5 mHz, however, the spectral amplitudes of the pressure sources are comparable to those of shear traction. Observed acoustic resonance between the atmosphere and the solid Earth at 3.7 and 4.4 mHz suggests that atmospheric disturbances are responsible for the surface pressure sources, although non-linear ocean wave processes are also candidates for the pressure sources. Excitation mechanisms of seismic hum should be considered as a superposition of the processes of the solid Earth, atmosphere and ocean

  14. Seismic Imaging and Monitoring

    SciTech Connect

    Huang, Lianjie

    2012-07-09

    I give an overview of LANL's capability in seismic imaging and monitoring. I present some seismic imaging and monitoring results, including imaging of complex structures, subsalt imaging of Gulf of Mexico, fault/fracture zone imaging for geothermal exploration at the Jemez pueblo, time-lapse imaging of a walkway vertical seismic profiling data for monitoring CO{sub 2} inject at SACROC, and microseismic event locations for monitoring CO{sub 2} injection at Aneth. These examples demonstrate LANL's high-resolution and high-fidelity seismic imaging and monitoring capabilities.

  15. Seismic Waveguide of Metamaterials

    NASA Astrophysics Data System (ADS)

    Kim, Sang-Hoon; Das, Mukunda P.

    We developed a new method of an earthquake-resistant design to support conventional aseismic system using acoustic metamaterials. The device is an attenuator of a seismic wave that reduces the amplitude of the wave exponentially. Constructing a cylindrical shell-type waveguide composed of many Helmholtz resonators that creates a stop-band for the seismic frequency range, we convert the seismic wave into an attenuated one without touching the building that we want to protect. It is a mechanical way to convert the seismic energy into sound and heat.

  16. Modernization of the Slovenian National Seismic Network

    NASA Astrophysics Data System (ADS)

    Vidrih, R.; Godec, M.; Gosar, A.; Sincic, P.; Tasic, I.; Zivcic, M.

    2003-04-01

    The Environmental Agency of the Republic of Slovenia, the Seismology Office is responsible for the fast and reliable information about earthquakes, originating in the area of Slovenia and nearby. In the year 2000 the project Modernization of the Slovenian National Seismic Network started. The purpose of a modernized seismic network is to enable fast and accurate automatic location of earthquakes, to determine earthquake parameters and to collect data of local, regional and global earthquakes. The modernized network will be finished in the year 2004 and will consist of 25 Q730 remote broadband data loggers based seismic station subsystems transmitting in real-time data to the Data Center in Ljubljana, where the Seismology Office is located. The remote broadband station subsystems include 16 surface broadband seismometers CMG-40T, 5 broadband seismometers CMG-40T with strong motion accelerographs EpiSensor, 4 borehole broadband seismometers CMG-40T, all with accurate timing provided by GPS receivers. The seismic network will cover the entire Slovenian territory, involving an area of 20,256 km2. The network is planned in this way; more seismic stations will be around bigger urban centres and in regions with greater vulnerability (NW Slovenia, Krsko Brezice region). By the end of the year 2002, three old seismic stations were modernized and ten new seismic stations were built. All seismic stations transmit data to UNIX-based computers running Antelope system software. The data is transmitted in real time using TCP/IP protocols over the Goverment Wide Area Network . Real-time data is also exchanged with seismic networks in the neighbouring countries, where the data are collected from the seismic stations, close to the Slovenian border. A typical seismic station consists of the seismic shaft with the sensor and the data acquisition system and, the service shaft with communication equipment (modem, router) and power supply with a battery box. which provides energy in case

  17. The critical angle in seismic interferometry

    USGS Publications Warehouse

    Van Wijk, K.; Calvert, A.; Haney, M.; Mikesell, D.; Snieder, R.

    2008-01-01

    Limitations with respect to the characteristics and distribution of sources are inherent to any field seismic experiment, but in seismic interferometry these lead to spurious waves. Instead of trying to eliminate, filter or otherwise suppress spurious waves, crosscorrelation of receivers in a refraction experiment indicate we can take advantage of spurious events for near-surface parameter extraction for static corrections or near-surface imaging. We illustrate this with numerical examples and a field experiment from the CSM/Boise State University Geophysics Field Camp.

  18. High Resolution Seismic Imaging of the Brawley Seismic Fault Zone

    NASA Astrophysics Data System (ADS)

    Goldman, M.; Catchings, R. D.; Rymer, M. J.; Lohman, R. B.; McGuire, J. J.; Sickler, R. R.; Criley, C.; Rosa, C.

    2011-12-01

    In March 2010, we acquired a series of high-resolution P-wave seismic reflection and refraction data sets across faults in the Brawley seismic zone (BSZ) within the Salton Sea Geothermal Field (SSGF). Our objectives were to determine the dip, possible structural complexities, and seismic velocities within the BSZ. One dataset was 3.4 km long trending east-west, and consisted of 334 shots recorded by a 2.4 km spread of 40 hz geophones placed every 10 meters. The spread was initially laid out from the first station at the eastern end of the profile to roughly 2/3 into the profile. After about half the shots, the spread was shifted from roughly 1/3 into the profile to the last station at the western end of the profile. P-waves were generated by Betsy-Seisgun 'shots' spaced every 10 meters. Initial analysis of first breaks indicate near-surface velocities of ~500-600 meters/sec, and deeper velocities of around 2000 meters/sec. Preliminary investigation of shot gathers indicate a prominent fault that extends to the ground surface. This fault is on a projection of the Kalin fault from about 40 m to the south, and broke the surface down to the west with an approximately north-south strike during a local swarm of earthquakes in 2005 and also slipped at the surface in association with the 2010 El Mayor-Cucapah earthquake in Baja California. The dataset is part of the combined Obsidian Creep data set, and provides the most detailed, publicly available subsurface images of fault structures in the BSZ and SSGF.

  19. Mass Wasting on the Moon: Implications for Seismicity

    NASA Technical Reports Server (NTRS)

    Weber, Renee; Nahm, Amanda; Schmerr, Nick; Yanites, Brian

    2016-01-01

    Seismicity estimates play an important role in creating regional geological characterizations, which are useful for understanding a planet's formation and evolution, and are of key importance to site selection for landed missions. Here we investigate the regional effects of seismicity in planetary environments with the goal of determining whether such surface features on the Moon, could be triggered by fault motion.

  20. Mass Wasting on the Moon: Implications for Seismicity

    NASA Technical Reports Server (NTRS)

    Weber, R. C.; Nahm, A. L.; Yanites, B.; Schmerr, N.

    2016-01-01

    Introduction: Seismicity estimates play an important role in creating regional geological characterizations, which are useful for understanding a planet's formation and evolution, and of key importance to site selection for landed missions. Here we investigate the regional effects of lunar seismicity with the goal of determining whether surface features such as landslides and boulder trails on the Moon are triggered by fault motion.

  1. Mass Wasting in Planetary Environments: Implications for Seismicity

    NASA Technical Reports Server (NTRS)

    Weber, Renee; Nahm, Amanda; Schmerr, Nick

    2015-01-01

    On Earth, mass wasting events such as rock falls and landslides are well known consequences of seismic activity. Here we investigate the regional effects of seismicity in planetary environments with the goal of determining whether such surface features on the Moon, Mars, and Mercury could be triggered by fault motion.

  2. Seismic spatial wavefield gradient and rotational rate measurements as new observables in land seismic exploration

    NASA Astrophysics Data System (ADS)

    Schmelzbach, Cedric; Sollberger, David; Van Renterghem, Cédéric; Häusler, Mauro; Robertsson, Johan; Greenhalgh, Stewart

    2016-04-01

    application of wavefield gradients is the removal of the free-surface effect on land-seismic recordings to obtain true amplitude and phase information of the desired upcoming wavefield from the recorded superposition of upcoming waves with downgoing reflected and downgoing mode-converted waves.

  3. Seismic Catalogue and Seismic Network in Haiti

    NASA Astrophysics Data System (ADS)

    Belizaire, D.; Benito, B.; Carreño, E.; Meneses, C.; Huerfano, V.; Polanco, E.; McCormack, D.

    2013-05-01

    The destructive earthquake occurred on January 10, 2010 in Haiti, highlighted the lack of preparedness of the country to address seismic phenomena. At the moment of the earthquake, there was no seismic network operating in the country, and only a partial control of the past seismicity was possible, due to the absence of a national catalogue. After the 2010 earthquake, some advances began towards the installation of a national network and the elaboration of a seismic catalogue providing the necessary input for seismic Hazard Studies. This paper presents the state of the works carried out covering both aspects. First, a seismic catalogue has been built, compiling data of historical and instrumental events occurred in the Hispaniola Island and surroundings, in the frame of the SISMO-HAITI project, supported by the Technical University of Madrid (UPM) and Developed in cooperation with the Observatoire National de l'Environnement et de la Vulnérabilité of Haiti (ONEV). Data from different agencies all over the world were gathered, being relevant the role of the Dominican Republic and Puerto Rico seismological services which provides local data of their national networks. Almost 30000 events recorded in the area from 1551 till 2011 were compiled in a first catalogue, among them 7700 events with Mw ranges between 4.0 and 8.3. Since different magnitude scale were given by the different agencies (Ms, mb, MD, ML), this first catalogue was affected by important heterogeneity in the size parameter. Then it was homogenized to moment magnitude Mw using the empirical equations developed by Bonzoni et al (2011) for the eastern Caribbean. At present, this is the most exhaustive catalogue of the country, although it is difficult to assess its degree of completeness. Regarding the seismic network, 3 stations were installed just after the 2010 earthquake by the Canadian Government. The data were sent by telemetry thought the Canadian System CARINA. In 2012, the Spanish IGN together

  4. The Aligned z~1 Radio Galaxy 3C 280

    NASA Astrophysics Data System (ADS)

    Ridgway, Susan E.; Stockton, Alan; Lacy, Mark

    2004-01-01

    The z~1 radio galaxy 3C 280 has a particularly striking rest-frame UV morphology, with multiple line and continuum components precisely aligned with the radio structure, including an obvious semicircular arc. Here we explore the nature of these various components by bringing together Hubble Space Telescope and ground-based imaging, ground-based spectroscopy, and radio mapping. From plausible decompositions of the spectra, we show that the continuum of the nuclear component is likely dominated by a combination of nebular thermal continuum, quasar light, and light from old stars. A component that falls directly on the probable path of the radio jet shows mostly nebular thermal continuum and includes contributions from a relatively young stellar population with age around 100 Myr. The arc appears to be completely dominated by line emission and nebular thermal continuum, with no evidence for a significant stellar contribution. Although much of the aligned light is in UV components, the underlying old elliptical galaxy is also well aligned with the radio axis. The elliptical galaxy is well fitted by a de Vaucouleurs profile, probably has a moderately old stellar population (~3 Gyr), and is a massive system with a velocity dispersion of σ~270 km s-1 that implies that it contains a supermassive black hole. Although the arc and the extended emission surrounding the eastern lobe suggest that interactions between the radio lobe and jet must have been important in creating the UV morphology, the ionization and kinematic properties in these components are more consistent with photoionization than shock excitation. 3C 280 may be a transition object between the compact steep-spectrum radio galaxies, which seem to be shock-dominated, and the extended radio sources, which may have evolved past this phase and rarely show shock signatures. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the

  5. Seismic structure of the moon - A summary of current status

    NASA Technical Reports Server (NTRS)

    Nakamura, Y.; Latham, G. V.; Dorman, H. J.; Duennebier, F. K.

    1976-01-01

    A seismic model of the moon, refined from previous models with the aid of new data and analyses for seismic events recorded by four Apollo lunar seismic stations and a gravimeter, is outlined. The current model has five zones. The crust is 55-60 km thick. The surface is covered by regolith of varying thicknesses and low seismic velocity. The seismic Q's are extremely high. The upper mantle, 250 km thick, is characterized by seismic velocities close to those of the earth's upper mantle, and shear wave Q of about 4000. Tidally controlled deep moonquakes are concentrated near the boundary of the middle mantle, 600-700 km thick. A lower mantle extending to an undetermined depth is characterized by high attenuation of shear waves. The existence of a low-velocity core is only tentatively proposed.

  6. Seismic azimuthal anisotropy in the oceanic lithosphere and asthenosphere from broadband surface wave analysis of OBS array records at 60 Ma seafloor

    NASA Astrophysics Data System (ADS)

    Takeo, A.; Kawakatsu, H.; Isse, T.; Nishida, K.; Sugioka, H.; Ito, A.; Shiobara, H.; Suetsugu, D.

    2016-03-01

    We analyzed seismic ambient noise and teleseismic waveforms of nine broadband ocean bottom seismometers deployed at a 60 Ma seafloor in the southeastward of Tahiti island, the South Pacific, by the Tomographic Investigation by seafloor ARray Experiment for the Society hotspot project. We first obtained one-dimensional shear wave velocity model beneath the array from average phase velocities of Rayleigh waves at a broadband period range of 5-200 s. The obtained model shows a large velocity reduction at depths between 40 and 80 km, where the lithosphere-asthenosphere boundary might exist. We then estimated shear wave azimuthal anisotropy at depths of 20-100 km by measuring azimuthal dependence of phase velocities of Rayleigh waves. The obtained model shows peak-to-peak intensity of the azimuthal anisotropy of 2%-4% with the fastest azimuth of NW-SE direction both in the lithosphere and asthenosphere. This result suggests that the ancient flow frozen in the lithosphere is not perpendicular to the strike of the ancient mid-ocean ridge but is roughly parallel to the ancient plate motion at depths of 20-60 km. The fastest azimuths in the current asthenosphere are subparallel to current plate motion at depths of 60-100 km. Additional shear wave splitting analysis revealed possible perturbations of flow in the mantle by the hot spot activities and implied the presence of azimuthal anisotropy in the asthenosphere down to a depth of 190-210 km.

  7. Finding Large Aperture Fractures in Geothermal Resource Areas Using a Three-Component Long-Offset Surface Seismic Survey, PSInSAR and Kinematic Structural Analysis

    SciTech Connect

    Teplow, William J.; Warren, Ian

    2015-08-12

    The DOE cost-share program applied innovative and cutting edge seismic surveying and processing, permanent scatter interferometry-synthetic aperture radar (PSInSAR) and structural kinematics to the exploration problem of locating and mapping largeaperture fractures (LAFs) for the purpose of targeting geothermal production wells. The San Emidio geothermal resource area, which is under lease to USG, contains production wells that have encountered and currently produce from LAFs in the southern half of the resource area (Figure 2). The USG lease block, incorporating the northern extension of the San Emidio geothermal resource, extends 3 miles north of the operating wellfield. The northern lease block was known to contain shallow thermal waters but was previously unexplored by deep drilling. Results of the Phase 1 exploration program are described in detail in the Phase 1 Final Report (Teplow et al., 2011). The DOE cost shared program was completed as planned on September 30, 2014. This report summarizes results from all of Phase 1 and 2 activities.

  8. ROSAT observations of the supernova remnant 3C 400.2

    NASA Astrophysics Data System (ADS)

    Saken, Jon M.; Long, K. S.; Blair, W. P.; Winkler, P. F.

    1995-04-01

    We have used the ROSAT point source proportional counter (PSPC) to examine the X-ray emission from 3C 400.2, a supernova remnant (SNR) which is a member of a class of remnants with limb-brightened radio and centrally condensed X-ray morphologies. The X-ray emission fills the radio shell and is characterized by an interior peak in the northwest region of the remnant. Otherwise, the surface brightness has a relatively smooth distribution. The X-ray peak is not correlated with any radio features or with the observed optical filaments. The PSPC X-ray spectrum is not well fitted by a power-law model but can be described in terms of thermal emission from a hot plasma with solar abundances. The only point source along the line of sight to the SNR is associated with a bright foreground F8 star. Thus the X-ray emission from 3C 400.2 is unlikely to be due to synchrotron radiation from an active pulsar. If the emission arises from a thermal plasma and the absorbing column along the line of sight to 3C 400.2 is 7.8 x 1021sq cm, then the temperature of the plasma is 0.27 keV, and the 0.4-2.4 keV X-ray luminosity is 1.3 x 1036 ergs/s for an assumed distance of 6 kpc. An X-ray hardness ratio map shows a slight increase in the hardness of the emission in the regions of the remnant with a higher X-ray surface brightness. Assuming uniform absorption across the remnant, this increase implies the temperature is approximately 1.5 times greater in the high surface brightness regions of SNR. The relatively uniform spectrum and the anticorrelation between X-ray and radio features seems to rule out the possibility that 3C 400.2 is actually two overlapping or interacting SNRs. The morphology of 3C 400.2 can be explained in terms of a multiphase interstellar medium (ISM) in which the primary shock is expanding into an ISM studded with dense cloudlets, if the clouds are evaporated or disrupted on a timescale which is long compared to the age of the SNR. It may also be possible to explain the

  9. ROSAT observations of the supernova remnant 3C 400.2

    NASA Technical Reports Server (NTRS)

    Saken, Jon M.; Long, K. S.; Blair, W. P.; Winkler, P. F.

    1995-01-01

    We have used the ROSAT point source proportional counter (PSPC) to examine the X-ray emission from 3C 400.2, a supernova remnant (SNR) which is a member of a class of remnants with limb-brightened radio and centrally condensed X-ray morphologies. The X-ray emission fills the radio shell and is characterized by an interior peak in the northwest region of the remnant. Otherwise, the surface brightness has a relatively smooth distribution. The X-ray peak is not correlated with any radio features or with the observed optical filaments. The PSPC X-ray spectrum is not well fitted by a power-law model but can be described in terms of thermal emission from a hot plasma with solar abundances. The only point source along the line of sight to the SNR is associated with a bright foreground F8 star. Thus the X-ray emission from 3C 400.2 is unlikely to be due to synchrotron radiation from an active pulsar. If the emission arises from a thermal plasma and the absorbing column along the line of sight to 3C 400.2 is 7.8 x 10(exp 21)sq cm, then the temperature of the plasma is 0.27 keV, and the 0.4-2.4 keV X-ray luminosity is 1.3 x 10(exp 36) ergs/s for an assumed distance of 6 kpc. An X-ray hardness ratio map shows a slight increase in the hardness of the emission in the regions of the remnant with a higher X-ray surface brightness. Assuming uniform absorption across the remnant, this increase implies the temperature is approximately 1.5 times greater in the high surface brightness regions of SNR. The relatively uniform spectrum and the anticorrelation between X-ray and radio features seems to rule out the possibility that 3C 400.2 is actually two overlapping or interacting SNRs. The morphology of 3C 400.2 can be explained in terms of a multiphase interstellar medium (ISM) in which the primary shock is expanding into an ISM studded with dense cloudlets, if the clouds are evaporated or disrupted on a timescale which is long compared to the age of the SNR. It may also be possible to

  10. Seismo-volcano source localization with triaxial broad-band seismic array

    NASA Astrophysics Data System (ADS)

    Inza, L. A.; Mars, J. I.; Métaxian, J. P.; O'Brien, G. S.; Macedo, O.

    2011-10-01

    Seismo-volcano source localization is essential to improve our understanding of eruptive dynamics and of magmatic systems. The lack of clear seismic wave phases prohibits the use of classical location methods. Seismic antennas composed of one-component (1C) seismometers provide a good estimate of the backazimuth of the wavefield. The depth estimation, on the other hand, is difficult or impossible to determine. As in classical seismology, the use of three-component (3C) seismometers is now common in volcano studies. To determine the source location parameters (backazimuth and depth), we extend the 1C seismic antenna approach to 3Cs. This paper discusses a high-resolution location method using a 3C array survey (3C-MUSIC algorithm) with data from two seismic antennas installed on an andesitic volcano in Peru (Ubinas volcano). One of the main scientific questions related to the eruptive process of Ubinas volcano is the relationship between the magmatic explosions and long-period (LP) swarms. After introducing the 3C array theory, we evaluate the robustness of the location method on a full wavefield 3-D synthetic data set generated using a digital elevation model of Ubinas volcano and an homogeneous velocity model. Results show that the backazimuth determined using the 3C array has a smaller error than a 1C array. Only the 3C method allows the recovery of the source depths. Finally, we applied the 3C approach to two seismic events recorded in 2009. Crossing the estimated backazimuth and incidence angles, we find sources located 1000 ± 660 m and 3000 ± 730 m below the bottom of the active crater for the explosion and the LP event, respectively. Therefore, extending 1C arrays to 3C arrays in volcano monitoring allows a more accurate determination of the source epicentre and now an estimate for the depth.

  11. Scanning Seismic Intrusion Detector

    NASA Technical Reports Server (NTRS)

    Lee, R. D.

    1982-01-01

    Scanning seismic intrusion detector employs array of automatically or manually scanned sensors to determine approximate location of intruder. Automatic-scanning feature enables one operator to tend system of many sensors. Typical sensors used with new system are moving-coil seismic pickups. Detector finds uses in industrial security systems.

  12. Borehole seismic unit

    NASA Astrophysics Data System (ADS)

    Seavey, R. W.

    1982-05-01

    Fracture orientation can be measured by using a triaxial geophone package located at the fracture interval within the wellbore. Seismic signals produced by the fracture can be recorded and measured to determine the direction of the fracture. A description of a borehole seismic unit and procedures to accomplish this task are reported.

  13. Seismic Computerized Alert Network

    USGS Publications Warehouse

    1986-01-01

    In 1985 the USGS devised a model for a Seismic Computerized Alert Network (SCAN) that would use continuous monitoring of seismic data from existing types of instruments to provide automatic, highly-reliable early warnings of earthquake shaking. In a large earthquake, substantial damaging ground motions may occur at great distances from the earthquake's epicenter.

  14. Optical seismic sensor systems and methods

    DOEpatents

    Beal, A. Craig; Cummings, Malcolm E.; Zavriyev, Anton; Christensen, Caleb A.; Lee, Keun

    2015-12-08

    Disclosed is an optical seismic sensor system for measuring seismic events in a geological formation, including a surface unit for generating and processing an optical signal, and a sensor device optically connected to the surface unit for receiving the optical signal over an optical conduit. The sensor device includes at least one sensor head for sensing a seismic disturbance from at least one direction during a deployment of the sensor device within a borehole of the geological formation. The sensor head includes a frame and a reference mass attached to the frame via at least one flexure, such that movement of the reference mass relative to the frame is constrained to a single predetermined path.

  15. Development of Vertical Cable Seismic System for Hydrothermal Deposit Survey

    NASA Astrophysics Data System (ADS)

    Asakawa, Eiichi; Okamoto, Taku; Sekino, Yoshihiro; Murakami, Fumitoshi; Mikada, Hitoshi; Takekawa, Junichi; Shimura, Takuya

    2010-05-01

    several types of sources (GI gun, water gun and piezotranceducer) and receivers (hydrophone and 3C accelerometer) as well as different types of positioning system. We will be able to plan a suitable survey for hydrothermal deposit using these results. The 2D VCS data is processed. It follows the walk-away VSP processing, including wave field separation and depth migration. The result gives clearer image than the conventional seismic section. Prestack depth migration is applied to 3D data to obtain good quality of the 3D depth volume. Through the survey in Lake Biwa, we have established the total VCS procedure, that is, pre-survey study, data acquisition system, field operation, data processing. We have concluded that VCS is one of the promising seismic surveys for hydrothermal deposit.

  16. AlN thin films grown on epitaxial 3C-SiC (100) for piezoelectric resonant devices

    SciTech Connect

    Lin, Chih-Ming; Senesky, Debbie G.; Pisano, Albert P.; Lien, Wei-Cheng; Felmetsger, Valery V.; Hopcroft, Matthew A.

    2010-10-04

    Highly c-axis oriented heteroepitaxial aluminum nitride (AlN) films were grown on epitaxial cubic silicon carbide (3C-SiC) layers on Si (100) substrates using alternating current reactive magnetron sputtering at temperatures between approximately 300-450 deg. C. The AlN films were characterized by x-ray diffraction, scanning electron microscope, and transmission electron microscopy. A two-port surface acoustic wave device was fabricated on the AlN/3C-SiC/Si composite structure, and an expected Rayleigh mode exhibited a high acoustic velocity of 5200 m/s. The results demonstrate the potential of utilizing AlN films on epitaxial 3C-SiC layers to create piezoelectric resonant devices.

  17. GRID3C: Computer program for generation of C type multilevel, three dimensional and boundary conforming periodic grids

    NASA Technical Reports Server (NTRS)

    Dulikravich, D. S.

    1982-01-01

    A fast computer program, GRID3C, was developed for accurately generating periodic, boundary conforming, three dimensional, consecutively refined computational grids applicable to realistic axial turbomachinery geometries. The method is based on using two functions to generate two dimensional grids on a number of coaxial axisymmetric surfaces positioned between the centerbody and the outer radial boundary. These boundary fitted grids are of the C type and are characterized by quasi-orthogonality and geometric periodicity. The built in nonorthogonal coordinate stretchings and shearings cause the grid clustering in the regions of interest. The stretching parameters are part of the input to GRID3C. In its present version GRID3C can generate and store a maximum of four consecutively refined three dimensional grids. The output grid coordinates can be calculated either in the Cartesian or in the cylindrical coordinate system.

  18. USING RECENT ADVANCES IN 2D SEISMIC TECHNOLOGY AND SURFACE GEOCHEMISTRY TO ECONOMICALLY REDEVELOP A SHALLOW SHELF CARBONATE RESERVOIR: VERNON FIELD, ISABELLA COUNTY, MI.

    SciTech Connect

    James R. Wood; T.J. Bornhorst; S.D. Chittichk; William B. Harrison; W. Quinlan

    2001-01-01

    The geochemical sampling team collected additional 148 samples at Vernon Field along 5 new traverses. Most of the locations were sampled for three types of analyses: microbial, iodine and enzyme leach; no results from the second batch of samples were available in time for this report. In addition to the sampling, a study was begun on the feasibility of collecting and analyzing hydrocarbon gases (C1-C8) directly. Although several companies offer these services, the cost ($200-300/sample w/o sampling fee) is high, on par with the cost of a 3D seismic survey, and may not include the raw data. However direct sampling of reservoir gases collecting in the soil appear to offer the best approach and should be included in this study. It would probably work well at Vernon Field. It may be possible to lower costs considerably; initial estimates of $20/sample for GCMS (Gas Chromatography--mass spectrometry) analysis are attractive and might induce to Michigan producers to include soil surveys in their routine field work-ups. A complete set of digital data was assembled for Vernon Field and nearby locations. The set consists of well locations, formation top picks, lithologies and scanned images of driller's reports and scout tickets. Well logs are still being located. The annual meeting for the Class Revisit work group is tentatively scheduled for the week of March 1-7 in Tampa, Fl. By that time all of the geochemical data will be available and final decisions regarding drilling can be made.

  19. Spatial Distributed Seismicity Model of Seismic Hazard Mapping in the North-China Region: A Comparison with the GSHAP

    NASA Astrophysics Data System (ADS)

    Zhong, Q.; Shi, B.; Meng, L.

    2010-12-01

    The North China is one of the most seismically active regions in the mainland China. The moderate to large earthquakes have occurred here throughout history, resulting in huge losses of human life and properties. With the probabilistic seismic hazard analysis (PSHA) approach, we investigate the influence of different seismic environments, incorporating both near surface soil properties and distributed historical and modern seismicity. A simplified seismic source model, derived with the consideration of regional active fault distributions, is presented for the North China region. The spatial distributed seismicity model of PSHA is used to calculate the level of ground motion likely to be exceeded in a given time period. Following Frankel (1995) approach of circular Gaussian smoothing procedure, in the PSHA’s calculation, we proposed the fault-rupture-oriented elliptical Gaussian smoothing with the assumptions that earthquakes occur on faults or fault zones of past earthquakes to delineate the potential seismic zones (Lapajine et al., 2003). This is combined with regional active fault strike directions and the seismicity distribution patterns. Next Generation Attenuation model ((NGA), Boore et al., 2007) is used in generating hazard map for PGA with 2%, 5%, and 10 % probability of being exceeded in 50 years, and the resultant hazard map is compared with the result given by Global Seismic Hazard Assessment Project (GSHAP). There is general agreement for PGA distribution patterns between the results of this study and the GSHAP map that used the same seismic source zones. However, peak ground accelerations predicted in this study are typically 10-20% less than those of the GSHAP, and the seismic source models, such as fault distributions and regional seismicity used in the GSHAP seem to be oversimplified. We believe this study represents an improvement on prior seismic hazard evaluations for the region. In addition to the updated input data, we believe that, by

  20. GRAIL Refinements to Lunar Seismic Structure

    NASA Technical Reports Server (NTRS)

    Weber, Renee C.; Schmerr, Nicholas C.

    2014-01-01

    Joint interpretation of disparate geophysical datasets helps reduce drawbacks that can result from analyzing them individually. The Apollo seismic network was situated on the lunar nearside surface in a roughly equilateral triangle having sides approximately 1000 km long, with stations 12/14 nearly co-located at one corner. Due to this limited geographical extent, near-surface ray coverage from moonquakes is low, but increases with depth. In comparison, gravity surveys and their resulting gravity anomaly maps have traditionally offered optimal resolution at crustal depths. Gravimetric maps and seismic data sets are therefore well suited to joint inversion, since the complementary information reduces inherent model ambiguity. Previous joint inversions of the Apollo seismic data (seismic phase arrival times) and Clementine- or Lunar Prospector-derived gravity data (mass and moment of inertia) attempted to recover the subsurface structure of the Moon by focusing on hypothetical lunar compositions that explored the density/velocity relationship. These efforts typically searched for the best fitting thermodynamically calculated velocity/density model, and allowed variables like core size, velocity, and/or composition to vary freely. Seismic velocity profiles derived from the Apollo seismic data through travel time inversion vary both in the depth of the crust and mantle layers, and the seismic velocities and densities assigned to those layers. The lunar mass and moment of inertia likewise only constrain gross variations in the density profile beyond that of a uniform density sphere. As a result, composition and structure models previously obtained by jointly inverting these data retain the original uncertainties inherent in the input data sets. We perform a joint inversion of Apollo seismic delay times and gravity data collected by the GRAIL lunar gravity mission, in order to recover seismic velocity and density as a function of latitude, longitude, and depth within the

  1. GRAIL Refinements to Lunar Seismic Structure

    NASA Technical Reports Server (NTRS)

    Weber, Renee C.; Schmerr, Nicholas C.

    2013-01-01

    Joint interpretation of disparate geophysical datasets helps to reduce drawbacks that can result from analyzing them individually. The Apollo seismic network was situated on the lunar nearside surface in a roughly equilateral triangle having sides approximately 1000 km long, with stations 12/14 nearly co-located at one corner. Due to this limited geographical extent, near-surface ray coverage from moonquakes is low, but increases with depth. In comparison, gravity surveys and their resulting gravity anomaly maps have traditionally offered optimal resolution at crustal depths. Gravimetric maps and seismic data sets are therefore well suited to joint inversion, since the complementary information reduces inherent model ambiguity. Previous joint inversions of the Apollo seismic data (seismic phase arrival times) and Clementine- or Lunar Prospector-derived gravity data (mass and moment of inertia) attempted to recover the subsurface structure of the Moon by focusing on hypothetical lunar compositions that explore the density/velocity relationship. These efforts typically search for the best fitting thermodynamically calculated velocity/density model, allowing variables like core size, velocity, and/or composition to vary freely. Seismic velocity profiles previously derived from the Apollo seismic data through inversion of travel times vary both in the depth of the crust and mantle layers, and the seismic velocities and densities assigned to those layers. The lunar mass and moment of inertia likewise only constrain gross variations in the density profile beyond that of a uniform density sphere. As a result, composition and structure models previously obtained by jointly inverting these data retain the original uncertainties inherent in the input data sets. We will perform a joint inversion of Apollo seismic delay times and gravity data collected by the GRAIL lunar gravity mission, in order to recover seismic velocities and density as a function of latitude, longitude

  2. USING RECENT ADVANCES IN 2D SEISMIC TECHNOLOGY AND SURFACE GEOCHEMISTRY TO ECONOMICALLY REDEVELOP A SHALLOW SHELF CARBONATE RESERVOIR: VERNON FIELD, ISABELLA COUNTY, MI

    SciTech Connect

    James R. Wood; W. Quinlan

    2003-10-01

    The principal objective of this demonstration project is to test surface geochemical techniques for detecting trace amounts of light hydrocarbons in pore gases as a means of reducing risk in hydrocarbon exploration and production. During this reporting period, a new field demonstration, Springdale Prospect in Manistee County, Michigan was begun to assess the validity and usefulness of the microbial surface geochemical technique. The surface geochemistry data showed a fair-to-good microbial anomaly that may indicate the presence of a fault or stratigraphic facies change across the drilling path. The surface geochemistry sampling at the original Bear Lake demonstration site was updated several months after the prospect was confirmed and production begun. As expected, the anomaly appears to be diminishing as the positive (apical) anomaly is replaced by a negative (edge) anomaly, probably due to the pressure draw-down in the reservoir.

  3. Observations of Titan 3C-4 Transtage Fragmentation Debris

    NASA Technical Reports Server (NTRS)

    Cowardin, Heather; Seitzer, P.; Abercromby, K.; Barker, E.; Cardona, T.; Krisko, P.; Lederer, S.

    2013-01-01

    The fragmentation of a Titan 3C-4 Transtage (1968-081) on 21 February 1992 is one of only two known break-ups in or near geosynchronous orbit. The original rocket body and 24 pieces of debris are currently being tracked by the US Space Surveillance Network (SSN). The rocket body (SSN# 3432) and several of the original fragments (SSN# 25000, 25001, 30000, and 33511) were observed in survey mode during 2004-2010 using the 0.6-m Michigan Orbital DEbris Survey Telescope (MODEST) in Chile using a broad R filter. This paper will present a size distribution for all calibrated magnitude data acquired on MODEST. Size distribution plots will also be shown using historical models for small fragmentation debris (down to 10 cm) believed to be associated with the Titan break-up. In November 2010, visible broadband photometry (Johnson/Kron-Cousins BVRI) was acquired with the 0.9-m Small and Moderate Aperture Research Telescope System (SMARTS) at the Cerro Tololo Inter-American Observatory (CTIO) in Chile on several Titan fragments (SSN# 25001, 33509, 33510) and the parent rocket body. Color index data will be used to determine the fragment brightness distribution and how the data compares to spacecraft materials measured in the laboratory using similar photometric measurement techniques. In 2012, the SSN added 16 additional fragments to the catalogue. MODEST acquired magnitude data on ten Titan fragments in late 2012 and early 2013. The magnitude distribution of all the observed fragments are analyzed as a function of time. In order to better characterize the breakup fragments spectral measurements were acquired on the original rocket body and five Titan fragments using the 6.5-m Magellan telescopes at Las Campanas Observatory in Chile. The telescopic spectra are compared with laboratory acquired spectra of materials (e.g., Aluminum and various paints) and categorized based on known absorption features for spacecraft materials.

  4. Multispectral Imaging of the Jet in 3C346

    NASA Astrophysics Data System (ADS)

    Smith, E. P.; Gardner, J. P.; Heap, S. R.; Baum, S. A.; O'Dea, C. P.

    1998-12-01

    Much progress has been made towards understanding the physics of extra-galactic jet flow in the past 10 years, through numerical modeling and detailed multi-frequency radio mapping. However, we still admit that basic parameters such as the magnetic field strength, the particle density, the bulk Lorentz factor and jet configuration (e.g., fast inner jet and slower outer sheath), and the nature and need for shocks remain unknown. However, by resolving the jets spectrally and spatially and pushing the observations to the higher energies with sufficient spatial resolution to resolve the cooling scale lengths, we can place unique constraints on the physical composition of, and acceleration mechanisms in, extra-galactic jets. The tightest constraints on the physics of jets come not from radio observations, but from observations in the optical, UV, and x-ray, where the lifetimes of the synchrotron emitting particles are measured in hundreds of years and the particles travel distances of hundreds of parsecs. To this end, we present radio through vacuum ultraviolet (STIS FUV-MAMA) spatially resolved images of the radio jet in 3C346 and use them examine the spatial variation of the spectral indices. Because the lifetime of the synchrotron radiating particles is inversely proportional to the observed frequency we can use the vastly different timescales (and therefore length scales) over which the radio (t ~ 10(5-7) yr.) and ultraviolet (t ~ 10(2-3) yr.) emitting particles cool to begin to place constraints on the magnetic field strengths. Also, the curvature of the spectrum as a function of position can be compared with aging models to constrain the magnetic field strength and to test the hypothesis that the magnetic field in radio jets may be substantially below equipartition (Heinz and Begelman 1997).

  5. Multiwavelength Observations of 3C66A in 2003

    NASA Astrophysics Data System (ADS)

    Boettcher, M.; Joshi, M.; Fossati, G.; Smith, I. A.; Mukherjee, R.; Bramel, D.; Cui, W.; WEBT Collaboration

    2004-08-01

    The radio-selected BL Lac object 3C66A was the target of an intensive multiwavelength observing campaign in the last quarter of 2003 and early 2004. It was monitored by the Whole Earth Blazar Telescope (WEBT) collaboration of optical observers, in tandem with 20 X-ray monitoring observations by the Rossi X-Ray Timing Explorer (RXTE), VHE gamma-ray observations by STACEE and VERITAS, and long-term monitoring at radio frequencies. In addition, 9 high-spatial-resolution observations using the VLA are being carried out during the campaign and throughout the year 2004 to follow possible structural changes of the source. A gradual brightening of the source over the course of the campaign was observed at all optical frequencies, culminating in a very bright flare at the end of January 2004. Optical light curves indicate intraday microvariability on time scales down to about 1.3 hours. No significant color-magnitude correlation for the entire data set was evident, but there is a slight indication of a hardness - intensity anti-correlation on intraday time scales. The X-ray spectrum is consistent with a power-law with a photon spectral index of ˜ 2.1, indicating that the RXTE energy band might be located right at the intersection of the synchrotron and the high-energy emission components of the broadband spectral energy distribution. No significant flux or spectral variability at X-ray energies was detected. We extracted snapshot spectral energy distributions at various times throughout the campaign, and present first spectral fits to those SEDs. This work was partially supported by NASA RXTE GO grant no. NNG 04GB13G.

  6. A Study of Near-Surface Seismic Methods on Terrain Susceptible to Landslides in the City of Campos do Jordão, State of São Paulo, Brazil.

    NASA Astrophysics Data System (ADS)

    Shams, B. S.

    2015-12-01

    This study seeks to prove the usefulness of near-surface seismic methods as complementary data to conventional geotechnical and geological data in the characterization of areas of landslide risk. The setting is located in a low income housing neighborhood in the city of Campos do Jordão, state of São Paulo, Brazil. The area was devastated by numerous landslides between December 1999 to January 2000 after heavy rainfall in the area. Currently the area is being monitored by the National Center for Monitoring and Warning of Natural Disasters (CEMADEN). The landslides in this area are known to be shallow. The survey line passes within a couple feet of the CEMADEN monitoring station which measures soil temperature, soil moisture, rainfall intensity, and rainfall accumulation (Mendes et. al 2015). Refraction and Multi-channel Analysis of Surface Waves (MASW) surveys were performed. In order to better identify the fundamental mode of the Rayleigh wave, separate surveys isolating the vertical and radial components of the Rayleigh wave were performed. By comparing the obtained Shear wave (Vs) and Compressional wave (Vp) profiles with the already known geotechnical data provided by CEMADEN and geological data from a previous study (Ahrendt 2005) of the site a better understanding of the geological interfaces that constitute the landslide prone area is obtained.

  7. Lunar seismic profiling experiment natural activity study

    NASA Technical Reports Server (NTRS)

    Duennebier, F. K.

    1976-01-01

    The Lunar Seismic Experiment Natural Activity Study has provided a unique opportunity to study the high frequency (4-20 Hz) portion to the seismic spectrum on the moon. The data obtained from the LSPE was studied to evaluate the origin and importance of the process that generates thermal moonquakes and the characteristics of the seismic scattering zone at the lunar surface. The detection of thermal moonquakes by the LSPE array made it possible to locate the sources of many events and determine that they are definitely not generated by astronaut activities but are the result of a natural process on the moon. The propagation of seismic waves in the near-surface layers was studied in a qualitative manner. In the absence of an adequate theoretical model for the propagation of seismic waves in the moon, it is not possible to assign a depth for the scattering layer. The LSPE data does define several parameters which must be satisfied by any model developed in the future.

  8. GRAIL Refinements to Lunar Seismic Structure

    NASA Technical Reports Server (NTRS)

    Weber, Renee C.; Schmerr, Nicholas C.

    2013-01-01

    Joint interpretation of disparate geophysical datasets helps reduce drawbacks that can result from analyzing them individually. The Apollo seismic network was situated on the lunar nearside surface in a roughly equilateral triangle having sides approximately 1000 km long, with stations 12/14 nearly co-located at one corner. Due to this limited geographical extent, near-surface ray coverage from moonquakes is low, but increase with depth. In comparison, gravity surveys and their resulting gravity anomaly maps have traditionally offered optimal resolution at crustal depths. Gravimetric maps and seismic data sets are therefor well suited to joint inversion, since the complementary information reduces inherent model ambiguity. We will perform a joint inversion of Apollo seismic delay times and gravity data collected by GRAIL lunar gravity mission, in order to recover seismic velocity and density as a function of latitude, longitude and depth within the Moon. We will relate density (rho) to seismic velocity (v) using a linear relationship that is allowed to be depth-dependent. The corresponding coefficient (B) can reflect a variety of material properties that vary with depth, including temperature and composition. The inversion seeks to recover the set of rho, v, and B perturbations that minimize (in a least-squares sense) the difference between the observed and calculated data.

  9. Preliminary validation of the refractivity from the new radio occultation sounder GNOS/FY-3C

    NASA Astrophysics Data System (ADS)

    Liao, Mi; Zhang, Peng; Yang, Guang-Lin; Bi, Yan-Meng; Liu, Yan; Bai, Wei-Hua; Meng, Xiang-Guang; Du, Qi-Fei; Sun, Yue-Qiang

    2016-03-01

    As a new member of the space-based radio occultation sounders, the GNOS (Global Navigation Satellite System Occultation Sounder) mounted on Fengyun-3C (FY-3C) has been carrying out atmospheric sounding since 23 September 2013. GNOS takes approximately 800 daily measurements using GPS (Global Positioning System) and Chinese BDS (BeiDou navigation satellite) signals. In this work, the atmospheric refractivity profiles from GNOS were compared with the ones obtained from the co-located ECMWF (European Centre for Medium-Range Weather Forecasts) reanalysis. The mean bias of the refractivity obtained through GNOS GPS (BDS) was found to be approximately -0.09 % (-0.04 %) from the near surface to up to 46 km. While the average standard deviation was approximately 1.81 % (1.26 %), it was as low as 0.75 % (0.53 %) in the range of 5-25 km, where best sounding results are usually achieved. Further, COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate) and MetOp/ GRAS (GNSS Receiver for Atmospheric Sounding) radio occultation data were compared with the ECMWF reanalysis; the results thus obtained could be used as reference data for GNOS. Our results showed that GNOS/FY-3C meets the design requirements in terms of accuracy and precision of the sounder. It possesses a sounding capability similar to COSMIC and MetOp/GRAS in the vertical range of 0-30 km, though it needs further improvement above 30 km. Overall, it provides a new data source for the global numerical weather prediction (NWP) community.

  10. Breakthroughs in Seismic and Borehole Characterization of Basalt Sequestration Targets

    SciTech Connect

    Sullivan, E. C.; Hardage, Bob A.; McGrail, B. Peter; Davis, Klarissa N.

    2011-04-01

    Mafic continental flood basalts form a globally important, but under-characterized CO2 sequestration target. The Columbia River Basalt Group (CRBG) in the northwestern U.S. is up to 5 km thick and covers over 168,000 km2. In India, flood basalts are 3 km thick and cover greater than 500,000 km2. Laboratory experiments demonstrate that the CRBG and other basalts react with formation water and super critical (sc) CO2 to precipitate carbonates, thus adding a potential mineral trapping mechanism to the standard trapping mechanisms of most other types of CO2 sequestration reservoirs. Brecciated tops of individual basalt flows in the CRBG form regional aquifers that locally have greater than 30% porosity and three Darcies of permeability. Porous flow tops are potential sites for sequestration of gigatons of scCO2 in areas where the basalts contain unpotable water and are at depths greater than 800 m. In this paper we report on the U.S. DOE Big Sky Regional Carbon Sequestration Partnership surface seismic and borehole geophysical characterization that supports a field test of capacity, integrity, and geochemical reactivity of CRBG reservoirs in eastern Washington, U.S.A. Traditional surface seismic methods have had little success in imaging basalt features in on-shore areas where the basalt is thinly covered by sediment. Processing of the experimental 6.5 km, 5 line 3C seismic swath included constructing an elastic wavefield model, identifying and separating seismic wave modes, and processing the swath as a single 2D line. Important findings include: (1) a wide variety of shear wave energy modes swamp the P-wave seismic records; (2) except at very short geophone offsets, ground roll overprints P-wave signal; and (3) because of extreme velocity contrasts, P-wave events are refracted at incidence angles greater than 7-15 degrees. Subsequent removal of S-wave and other noise during processing resulted in tremendous improvement in image quality. The application of wireline

  11. Apollo 14 active seismic experiment.

    NASA Technical Reports Server (NTRS)

    Watkins, J. S.; Kovach, R. L.

    1972-01-01

    Explosion seismic refraction data indicate that the lunar near-surface rocks at the Apollo 14 site consist of a regolith 8.5 meters thick and characterized by a compressional wave velocity of 104 meters per second. The regolith is underlain by a layer with a compressional wave velocity of 299 meters per second. The thickness of this layer, which we interpret to be the Fra Mauro Formation, is between 16 and 76 meters. The layer immediately beneath this has a velocity greater than 370 meters per second. We found no evidence of permafrost.

  12. Detection capability of the IMS seismic network based on ambient seismic noise measurements

    NASA Astrophysics Data System (ADS)

    Gaebler, Peter J.; Ceranna, Lars

    2016-04-01

    All nuclear explosions - on the Earth's surface, underground, underwater or in the atmosphere - are banned by the Comprehensive Nuclear-Test-Ban Treaty (CTBT). As part of this treaty, a verification regime was put into place to detect, locate and characterize nuclear explosion testings at any time, by anyone and everywhere on the Earth. The International Monitoring System (IMS) plays a key role in the verification regime of the CTBT. Out of the different monitoring techniques used in the IMS, the seismic waveform approach is the most effective technology for monitoring nuclear underground testing and to identify and characterize potential nuclear events. This study introduces a method of seismic threshold monitoring to assess an upper magnitude limit of a potential seismic event in a certain given geographical region. The method is based on ambient seismic background noise measurements at the individual IMS seismic stations as well as on global distance correction terms for body wave magnitudes, which are calculated using the seismic reflectivity method. From our investigations we conclude that a global detection threshold of around mb 4.0 can be achieved using only stations from the primary seismic network, a clear latitudinal dependence for the detection threshold can be observed between northern and southern hemisphere. Including the seismic stations being part of the auxiliary seismic IMS network results in a slight improvement of global detection capability. However, including wave arrivals from distances greater than 120 degrees, mainly PKP-wave arrivals, leads to a significant improvement in average global detection capability. In special this leads to an improvement of the detection threshold on the southern hemisphere. We further investigate the dependence of the detection capability on spatial (latitude and longitude) and temporal (time) parameters, as well as on parameters such as source type and percentage of operational IMS stations.

  13. Seismic Forecasting of Solar Activity

    NASA Technical Reports Server (NTRS)

    Braun, Douglas; Lindsey, Charles

    2001-01-01

    We have developed and improved helioseismic imaging techniques of the far-side of the Sun as part of a synoptic monitor of solar activity. In collaboration with the MIDI team at Stanford University we are routinely applying our analysis to images within 24 hours of their acquisition by SOHO. For the first time, real-time seismic maps of large active regions on the Sun's far surface are publicly available. The synoptic images show examples of active regions persisting for one or more solar rotations, as well as those initially detected forming on the solar far side. Until recently, imaging the far surface of the Sun has been essentially blind to active regions more than about 50 degrees from the antipode of disk center. In a paper recently accepted for publication, we have demonstrated how acoustic travel-time perturbations may be mapped over the entire hemisphere of the Sun facing away from the Earth, including the polar regions. In addition to offering significant improvements to ongoing space weather forecasting efforts, the procedure offers the possibility of local seismic monitoring of both the temporal and spatial variations in the acoustic properties of the Sun over the entire far surface.

  14. Observation of equipartition of seismic waves.

    PubMed

    Hennino, R; Trégourès, N; Shapiro, N M; Margerin, L; Campillo, M; van Tiggelen, B A; Weaver, R L

    2001-04-01

    Equipartition is a first principle in wave transport, based on the tendency of multiple scattering to homogenize phase space. We report observations of this principle for seismic waves created by earthquakes in Mexico. We find qualitative agreement with an equipartition model that accounts for mode conversions at the Earth's surface.

  15. A seismic risk for the lunar base

    NASA Technical Reports Server (NTRS)

    Oberst, Juergen; Nakamura, Yosio

    1992-01-01

    Shallow moonquakes, which were discovered during observations following the Apollo lunar landing missions, may pose a threat to lunar surface operations. The nature of these moonquakes is similar to that of intraplate earthquakes, which include infrequent but destructive events. Therefore, there is a need for detailed study to assess the possible seismic risk before establishing a lunar base.

  16. Simultaneous Multiwavelength Monitoring of 3C66A

    NASA Technical Reports Server (NTRS)

    Boettcher, M.

    2004-01-01

    The radio-selected BL Lac object 3C66A was the target of an intensive multiwavelength campaign from Sept. 2003 through Feb. 2004. It was monitored by the Whole Earth Blazar Telescope (WEBT) collaboration, in tandem with 20 X-ray monitoring observations by the Rossi X-Ray Timing Explorer (RXTE), VHE gamma-ray observations by STACEE and VERITAS, and long-term monitoring at radio frequencies. In addition. 9 observations using the VLBA are being carried out during the campaign and throughout the year 2004 to follow possible structural changes of the source. 21 pointings with RXTE during the period Sept. 15 - Dec. 27, 2003. All collected data have been fully analyzed, and first results have already been published at the 8th HEAD Meeting in New Orleans, LA, in Sept. 2004, and will also be presented at the 205th AAS Meeting in San Diego, CA, in Jan. 2005. A first Journal paper, to be submitted to the Astrophysical Journal, is currently in preparation, and we plan to have it ready for submission in January 2005. A gradual brightening of the source over the course of the campaign was observed at all optical frequencies, culminating in a very bright flare at the end of January 2004. Optical light curves indicate intraday microvariability on time scales down to about 1.3 hours. No significant color-magnitude correlation for the entire data set was evident, but there is a slight indication of a gradual spectral softening in the optical over the entire duration of multi-day outbursts (in both the rising and decaying phase). The X-ray spectrum is consistent with a power-law with a photon spectral index of approx. 2.1, indicating that the RXTE energy band might be located right at the intersection of the synchrotron and the high-energy emission components. No significant flux or spectral variability at X-ray energies was detected, though there seems to be a trend of very modest brightening in tandem with the optical flux. The first 4 VLBA epochs indicate a rather smooth jet with

  17. Multifrequency seismic detectability of seasonal thermoclines assessed from ARGO data

    NASA Astrophysics Data System (ADS)

    Ker, S.; Le Gonidec, Y.; Marié, L.

    2016-08-01

    Seismic oceanography is a developing research topic where new acoustic methods allow high-resolution teledetection of the thermohaline structure of the ocean. First implementations to study the Ocean Surface Boundary Layer have recently been achieved but remain very challenging due to the weakness and shallowness of such seismic reflectors. In this article, we develop a multifrequency seismic analysis of hydrographic data sets collected in a seasonally stratified midlatitude shelf by ARGO network floats to assess the detectability issue of shallow thermoclines. This analysis, for which sensitivity to the data reduction scheme used by ARGO floats for the transmission of the profiles is discussed, allows characterizing both the depth location and the frequency dependency of the dominant reflective feature of such complex structures. This approach provides the first statistical distribution of the range of variability of the frequency-dependent seismic reflection amplitude of the midlatitude seasonal thermoclines. We introduce a new parameter to quantify the overall capability of a multichannel seismic setup, including the source strength, the fold, and the ambient noise level, to detect shallow thermoclines. Seismic source signals are approximated by Ricker wavelets, providing quantitative guidelines to help in the design of seismic experiments targeting such oceanic reflectors. For shallow midlatitude seasonal thermoclines, we show that the detectability is optimal for seismic peak frequencies between 200 and 400 Hz: this means that airgun and Sparker sources are not well suited and that significant improvements of source devices will be necessary before seismic imaging of OSBL structures can be reliably attempted.

  18. Seismic Forecasting of Eruptions at Dormant StratoVolcanoes

    NASA Astrophysics Data System (ADS)

    White, R. A.

    2015-12-01

    Seismic monitoring data provide important constraints on tracking magmatic ascent and eruption. Based on direct experience with over 25 and review of over 10 additional eruption sequences at 24 volcanoes, we have identified 4 phases of precursory seismicity. 1) Deep (>20 km) low frequency (DLF) earthquakes occur near the base of the crust as magma rises toward crustal reservoirs. This seismicity is the most difficult to observe, owing to generally small magnitudes (M<2.5) the significant depth. 2) Distal volcano-tectonic (DVT) earthquakes occur on tectonic faults from a 2 to 30+ km distance laterally from (not beneath) the eventual eruption site as magma intrudes into and rises out of upper crustal reservoirs to depths of 2-3 km. A survey of 111 eruptions of 83 previously dormant volcanoes, (including all eruptions of VEI >4 since 1955) shows they were all preceded by significant DVT seismicity, usually felt. This DVT seismicity is easily observed owing to magnitudes generally reaching M>3.5. The cumulative DVT energy correlates to the intruding magma volume. 3) Low frequency (LF) earthquakes, LF tremor and contained explosions occur as magma interacts with the shallow hydrothermal system (<2 km depth), while the distal seismicity dies off.4) Shortly after this, repetitive self-similar proximal seismicity may occur and may dominate the seismic records as magma rises to the surface. We present some examples of this seismic progression to demonstrate that data from a single short-period vertical station are often sufficient to forecast eruption onsets.

  19. Probabilistic Seismic Hazard Analysis

    SciTech Connect

    Not Available

    1988-01-01

    The purpose of Probabilistic Seismic Hazard Analysis (PSHA) is to evaluate the hazard of seismic ground motion at a site by considering all possible earthquakes in the area, estimating the associated shaking at the site, and calculating the probabilities of these occurrences. The Panel on Seismic Hazard Analysis is charged with assessment of the capabilities, limitations, and future trends of PSHA in the context of alternatives. The report identifies and discusses key issues of PSHA and is addressed to decision makers with a modest scientific and technical background and to the scientific and technical community. 37 refs., 19 figs.

  20. Spatially resolved electron tunneling spectroscopy on single crystalline Rb{sub 3}C{sub 60}

    SciTech Connect

    Jess, P.; Hubler, U.; Behler, S.; Thommen-Geiser, V.; Lang, H.P.; Guentherodt, H.

    1996-03-01

    A Rb{sub 3}C{sub 60} single crystal ({ital T}{sub {ital c}}=30.5 K) is investigated in the superconducting state at 2.8 K by scanning tunneling microscopy and scanning tunneling spectroscopy (STS). STS data reveals a spatial variation of the superconducting energy gap {Delta} on a scale of 50 nm ({Delta}=2.6{endash}5.2 meV; 2{Delta}/{ital k}{sub {ital BT}}{sub {ital c}}=2.0{endash}4.0). This behavior is attributed to varying stoichiometry on the sample surface. An investigation of a Rb{sub 3}C{sub 60} facet shows that {ital I}({ital V}) characteristics even vary on molecular scale. {ital I}({ital V}) curves acquired between fullerene molecules exhibit a nonvanishing slope at zero bias whereas {ital I}({ital V}) characteristics measured above molecules exhibit vanishing slope at zero bias. {copyright} {ital 1996 American Vacuum Society}

  1. Structure and Properties of Magnetic (Co, Fe, Fe{sub 3}C and Ni) Carbon Beads

    SciTech Connect

    Leonowicz, Marcin; Izydorzak, Marta; Pomogailo, Anatolii D.; Dzhardimalieva, Gulzhian I.

    2010-12-02

    Nanoparticles exhibit unique physical properties due to the surface or quantum-size effects. Particular attention has been focused on magnetic nanoparticles and substantial progress has been done in this field. In this work magnetic composites, consisting of elementary metals or carbides nanocrystallites, stabilized in carbon matrix, were prepared by the procedure comprising formation of appropriate metal acrylamide complexes, followed by frontal polymerization and pyrolysis of the polymer at various temperatures. Application of frontal polymerization and further pyrolysis enables formation of composite beads consisting of Co, Fe, Fe{sub 3}C or Ni nanocrystallites stabilized in carbon matrix. It was found that the lowest pyrolysis temperature, which enables the production of metallic nanocrystallites, was 673 K for Co and Ni, and 773 K for Fe. The magnetic properties of the beads, percentage of the metallic component, their composition and shape depended on the pyrolysis temperature. Extracts on the basis of composites containing Fe{sub 3}C showed no cytotoxicity, whereas those containing Co and Ni exhibited negligible cytotoxicity up to concentrations of 6.25 mg/ml.

  2. Preliminary validation of refractivity from a new radio occultation sounder GNOS/FY-3C

    NASA Astrophysics Data System (ADS)

    Liao, M.; Zhang, P.; Yang, G. L.; Bi, Y. M.; Liu, Y.; Bai, W. H.; Meng, X. G.; Du, Q. F.; Sun, Y. Q.

    2015-09-01

    As a new member of space-based radio occultation sounder, the GNOS (Global Navigation Satellite System Occultation Sounder) mounted on FY-3C has been carrying out the atmospheric sounding since 23 September 2013. GNOS takes a daily measurement up to 800 times with GPS (Global Position System) and Chinese BDS (BeiDou navigation satellite) signals. The refractivity profiles from GNOS are compared with the co-located ECMWF (European Centre for Medium-Range Weather Forecasts) analyses in this paper. Bias and standard deviation have being calculated as the function of altitude. The mean bias is about 0.2 % from the near surface to 35 km. The average standard deviation is within 2 % while it is down to about 1 % in the range 5-30 km where best soundings are usually made. To evaluate the performance of GNOS, COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate) and GRAS/METOP-A (GNSS Receiver for Atmospheric Sounding) data are also compared to ECMWF analyses as the reference. The results show that GNOS/FY-3C meets the requirements of the design well. It possesses a sounding capability similar to COSMIC and GRAS in the vertical range of 0-30 km, though it needs improvement in higher altitude. Generally, it provides a new data source for global NWP (numerical weather prediction) community.

  3. Recent Impacts on Mars: Cluster Properties and Seismic Signal Predictions

    NASA Astrophysics Data System (ADS)

    Justine Daubar, Ingrid; Schmerr, Nicholas; Banks, Maria; Marusiak, Angela; Golombek, Matthew P.

    2016-10-01

    Impacts are a key source of seismic waves that are a primary constraint on the formation, evolution, and dynamics of planetary objects. Geophysical missions such as InSight (Banerdt et al., 2013) will monitor seismic signals from internal and external sources. New martian craters have been identified in orbital images (Malin et al., 2006; Daubar et al., 2013). Seismically detecting such impacts and subsequently imaging the resulting craters will provide extremely accurate epicenters and source crater sizes, enabling calibration of seismic velocities, the efficiency of impact-seismic coupling, and retrieval of detailed regional and local internal structure.To investigate recent impact-induced seismicity on Mars, we have assessed ~100 new, dated impact sites. In approximately half of new impacts, the bolide partially disintegrates in the atmosphere, forming multiple craters in a cluster. We incorporate the resulting, more complex, seismic effects in our model. To characterize the variation between sites, we focus on clustered impacts. We report statistics of craters within clusters: diameters, morphometry indicating subsurface layering, strewn-field azimuths indicating impact direction, and dispersion within clusters indicating combined effects of bolide strength and elevation of breakup.Measured parameters are converted to seismic predictions for impact sources using a scaling law relating crater diameter to the momentum and source duration, calibrated for impacts recorded by Apollo (Lognonne et al., 2009). We use plausible ranges for target properties, bolide densities, and impact velocities to bound the seismic moment. The expected seismic sources are modeled in the near field using a 3-D wave propagation code (Petersson et al., 2010) and in the far field using a 1-D wave propagation code (Friederich et al., 1995), for a martian seismic model. Thus we calculate the amplitudes of seismic phases at varying distances, which can be used to evaluate the detectability

  4. USING RECENT ADVANCES IN 2D SEISMIC TECHNOLOGY AND SURFACE GEOCHEMISTRY TO ECONOMICALLY REDEVELOP A SHALLOW SHELF CARBONATE RESERVOIR; VERNON FIELD, ISABELLA COUNTY, MI.

    SciTech Connect

    James R. Wood; A. Wylie; W. Quinlan

    2004-01-01

    The principal objective of this demonstration project is to test surface geochemical techniques for detecting trace amounts of light hydrocarbons in pore gases as a means of reducing risk in hydrocarbon exploration and production. During this reporting period, a new field demonstration, Springdale Prospect in Manistee County, Michigan was begun to assess the validity and usefulness of the microbial surface geochemical technique. The surface geochemistry data showed a fair-to-good microbial anomaly that may indicate the presence of a fault or stratigraphic facies change across the drilling path. The main news this reporting period is the confirmed discovery of producing hydrocarbons at the State Springdale & O'Driscoll No.16-16 demonstration well in Manistee County. This well was spudded in late November, tested and put on production in December 2003. To date it is flowing nearly 100 barrels of liquid hydrocarbons per day, which is a good well in Michigan. Reserves have not been established yet. The surface geochemistry sampling at the Springdale demonstration site will be repeated this spring after the well has been on production for several months to see if the anomaly pattern changes. We expect that the anomaly will diminish as the original positive (apical) anomaly is replaced by a negative (edge) anomaly, probably due to the pressure draw-down in the reservoir. This is the behavior that we observed at the Bear lake demonstration well reported last quarter.

  5. A Hammer-Impact, Aluminum, Shear-Wave Seismic Source

    USGS Publications Warehouse

    Haines, Seth S.

    2007-01-01

    Near-surface seismic surveys often employ hammer impacts to create seismic energy. Shear-wave surveys using horizontally polarized waves require horizontal hammer impacts against a rigid object (the source) that is coupled to the ground surface. I have designed, built, and tested a source made out of aluminum and equipped with spikes to improve coupling. The source is effective in a variety of settings, and it is relatively simple and inexpensive to build.

  6. Method of migrating seismic records

    DOEpatents

    Ober, Curtis C.; Romero, Louis A.; Ghiglia, Dennis C.

    2000-01-01

    The present invention provides a method of migrating seismic records that retains the information in the seismic records and allows migration with significant reductions in computing cost. The present invention comprises phase encoding seismic records and combining the encoded seismic records before migration. Phase encoding can minimize the effect of unwanted cross terms while still allowing significant reductions in the cost to migrate a number of seismic records.

  7. Three-component borehole wall-locking seismic detector

    DOEpatents

    Owen, Thomas E.

    1994-01-01

    A seismic detector for boreholes is described that has an accelerometer sensor block for sensing vibrations in geologic formations of the earth. The density of the seismic detector is approximately matched to the density of the formations in which the detector is utilized. A simple compass is used to orient the seismic detector. A large surface area shoe having a radius approximately equal to the radius of the borehole in which the seismic detector is located may be pushed against the side of the borehole by actuating cylinders contained in the seismic detector. Hydraulic drive of the cylinders is provided external to the detector. By using the large surface area wall-locking shoe, force holding the seismic detector in place is distributed over a larger area of the borehole wall thereby eliminating concentrated stresses. Borehole wall-locking forces up to ten times the weight of the seismic detector can be applied thereby ensuring maximum detection frequency response up to 2,000 hertz using accelerometer sensors in a triaxial array within the seismic detector.

  8. Seismic sequences in the Sombrero Seismic Zone

    NASA Astrophysics Data System (ADS)

    Pulliam, J.; Huerfano, V. A.; ten Brink, U.; von Hillebrandt, C.

    2007-05-01

    The northeastern Caribbean, in the vicinity of Puerto Rico and the Virgin Islands, has a long and well-documented history of devastating earthquakes and tsunamis, including major events in 1670, 1787, 1867, 1916, 1918, and 1943. Recently, seismicity has been concentrated to the north and west of the British Virgin Islands, in the region referred to as the Sombrero Seismic Zone by the Puerto Rico Seismic Network (PRSN). In the combined seismicity catalog maintained by the PRSN, several hundred small to moderate magnitude events can be found in this region prior to 2006. However, beginning in 2006 and continuing to the present, the rate of seismicity in the Sombrero suddenly increased, and a new locus of activity developed to the east of the previous location. Accurate estimates of seismic hazard, and the tsunamigenic potential of seismic events, depend on an accurate and comprehensive understanding of how strain is being accommodated in this corner region. Are faults locked and accumulating strain for release in a major event? Or is strain being released via slip over a diffuse system of faults? A careful analysis of seismicity patterns in the Sombrero region has the potential to both identify faults and modes of failure, provided the aggregation scheme is tuned to properly identify related events. To this end, we experimented with a scheme to identify seismic sequences based on physical and temporal proximity, under the assumptions that (a) events occur on related fault systems as stress is refocused by immediately previous events and (b) such 'stress waves' die out with time, so that two events that occur on the same system within a relatively short time window can be said to have a similar 'trigger' in ways that two nearby events that occurred years apart cannot. Patterns that emerge from the identification, temporal sequence, and refined locations of such sequences of events carry information about stress accommodation that is obscured by large clouds of

  9. An Integrated Multi-component Processing and Interpretation Framework for 3D Borehole Seismic Data

    SciTech Connect

    M. Karrenbach

    2004-04-01

    to perform advanced processing, imaging and analysis tests in the future during this project. Preparation of our software libraries for interfacing 3C display classes and mechanisms were carried out. We extensively tested the OIV and QT software library for usefulness in displaying 3C data and we thoroughly tested 3D scene graph communication between QT, OpenInventor and our existing software classes, which lead to optimizing the interface between them. We assembled an application skeleton which serves as a basis for future high level software tools. Based on this skeleton we implemented a 3C Work Bench tool as the primary prototyping tool for all future developments within this project. This work bench allows to load, manipulate and display data items. We demonstrated its basic functionality by loading source maps, horizons, seismic and velocity volumes, well logs into the tool, performing basic QC steps as is necessary in normal processing. All tasks were performed successfully, ensuring the continued progress of this project as outlined in the original proposal. Deliverables generated during this time period consist of reporting details and synthetically modeled seismic data for a 3D layered geological model. The numerically modeled SEGY data, as well as the model representation data, are ready to be sent out to DOE facilities for archiving. Based on the successful conclusion of work performed during this six month period we continue to generate synthetically modeled 3D borehole seismic data, according to Tasks 2 and 3. At the same time we proceed to design, implement and test according to the original plan the basic data classes and the basic framework outlined in Tasks 5 through 8.

  10. Synthetic seismic signature of thermal mantle plumes

    NASA Astrophysics Data System (ADS)

    Goes, S.; Hansen, U.

    2003-04-01

    With increasing resolution in global tomographic models and targeted regional experiments the first seismic images of mantle plumes have emerged. In order to obtain a better idea of the expected seismic signature of a purely thermal mantle plume we perform a set of three-dimensional numerical experiments with parameters relevant to the Earth's mantle. The thermal plumes thus obtained are converted into P- and S-velocity structure taking into account the effect of temperature, pressure, an average mantle composition including phase transitions and anelasticity on the seismic velocities. Excess plume temperatures were constrained to be about 300oC below the lithosphere to be consistent with surface observations. Models with depth-dependent expansivity and conductivity and temperature and depth-dependent viscosity predict plumes that are 500-800 km wide in the lower mantle. An abrupt lowering of the viscosity above 660 km of at least a factor 30 can narrow upper mantle plumes to 100-200 km. Due to the varying sensitivity of seismic velocities to temperature with depth and mineralogy, variations in amplitude and width of the seismic plume do not coincide with the variations in the thermal structure of the plume. Anomalies of 2-4% are expected in the uppermost mantle. Reduced sensitivity in the transition zone as well as complexities due to phase boundary topography may hamper imaging continuous whole mantle plumes. Lower mantle plumes that are consistent with temperature constrasts of 100-300oC below the lithosphere will have seismic amplitudes of only 0.5-1%. Seismic anelasticity structure follows the thermal structure more closely and yields plume anomalies of 100-200% in dln(1/QS).

  11. The seismic design handbook

    SciTech Connect

    Naeim, F. )

    1989-01-01

    This book contains papers on the planning, analysis, and design of earthquake resistant building structures. Theories and concepts of earthquake resistant design and their implementation in seismic design practice are presented.

  12. BUILDING 341 Seismic Evaluation

    SciTech Connect

    Halle, J.

    2015-06-15

    The Seismic Evaluation of Building 341 located at Lawrence Livermore National Laboratory in Livermore, California has been completed. The subject building consists of a main building, Increment 1, and two smaller additions; Increments 2 and 3.

  13. USING RECENT ADVANCES IN 2D SEISMIC TECHNOLOGY AND SURFACE GEOCHEMISTRY TO ECONOMICALLY REDEVELOP A SHALLOW SHELF CARBONATE RESERVOIR: VERNON FIELD, ISABELLA COUNTY, MI.

    SciTech Connect

    James R. Wood; T.J. Bornhorst; S.D. Chittick; William B. Harrison; W. Quinlan

    2001-10-31

    Two major accomplishments resulted from Phase I. One is the success of the surface geochemistry program, which collected over 800 samples from the site of the 1st demonstration well in Vernon Field and has pretty well provided us with the tools to delineate favorable ground from unfavorable. The second is the recent detailed mapping of the Central Michigan Basin that for the first time revealed the presence of at least two major faults that control the location of many of the reservoirs in the Michigan Basin. These faults were located from structure maps obtained by contouring the surface of the Dundee Formation using top picks from 9861 wells in 14 counties. Faults were inferred where the contour lines were most dense (''stacked'').

  14. A Two-Dimensional Zirconium Carbide by Selective Etching of Al3C3 from Nanolaminated Zr3Al3C5.

    PubMed

    Zhou, Jie; Zha, Xianhu; Chen, Fan Y; Ye, Qun; Eklund, Per; Du, Shiyu; Huang, Qing

    2016-04-11

    The room-temperature synthesis of a new two-dimensional (2D) zirconium-containing carbide, Zr3C2T(z) MXene is presented. In contrast to traditional preparation of MXene, the layered ternary Zr3Al3C5 material instead of MAX phases is used as source under hydrofluoric acid treatment. The structural, mechanical, and electronic properties of the synthesized 2D carbide are investigated, combined with first-principles density functional calculations. A comparative study on the structrual stability of our obtained 2D Zr3C2T(z) and Ti3C2T(z) MXenes at elevated temperatures is performed. The obtained 2D Zr3C2T(z) exhibits relatively better ability to maintain 2D nature and strucural integrity compared to Ti-based Mxene. The difference in structural stability under high temperature condition is explained by a theoretical investigation on binding energy.

  15. Joint Inversion of Body-Wave Arrival Times and Surface-Wave Dispersion for Three-Dimensional Seismic Structure Around SAFOD

    NASA Astrophysics Data System (ADS)

    Zhang, Haijiang; Maceira, Monica; Roux, Philippe; Thurber, Clifford

    2014-11-01

    We incorporate body-wave arrival time and surface-wave dispersion data into a joint inversion for three-dimensional P-wave and S-wave velocity structure of the crust surrounding the site of the San Andreas Fault Observatory at Depth. The contributions of the two data types to the inversion are controlled by the relative weighting of the respective equations. We find that the trade-off between fitting the two data types, controlled by the weighting, defines a clear optimal solution. Varying the weighting away from the optimal point leads to sharp increases in misfit for one data type with only modest reduction in misfit for the other data type. All the acceptable solutions yield structures with similar primary features, but the smaller-scale features change substantially. When there is a lower relative weight on the surface-wave data, it appears that the solution over-fits the body-wave data, leading to a relatively rough V s model, whereas for the optimal weighting, we obtain a relatively smooth model that is able to fit both the body-wave and surface-wave observations adequately.

  16. USING RECENT ADVANCES IN 2D SEISMIC TECHNOLOGY AND SURFACE GEOCHEMISTRY TO ECONOMICALLY REDEVELOP A SHALLOW SHELF CARBONATE RESERVOIR: VERNON FIELD, ISABELLA COUNTY, MI

    SciTech Connect

    James R. Wood; A. Wylie; W. Quinlan

    2004-07-01

    The principal objective of this demonstration project is to test surface geochemical techniques for detecting trace amounts of light hydrocarbons in pore gases as a means of reducing risk in hydrocarbon exploration and production. During this reporting period, plans were finalized for additional surface geochemical sampling in the new Springdale Prospect field demonstration in Manistee County, Michigan. Plans were also developed to acquire additional surface geochemical data in the vicinity of the Bagley Prospect area in Otsego County, Michigan. The main news this reporting period is the continued success in the Springdale demonstration area. The State Springdale & O'Driscoll No.16-16 and the State Springdale & Herban 12-16 horizontal demonstration wells in Manistee County, Michigan are both flowing nearly 100 barrels of liquid hydrocarbons per day plus gas, which are good wells in Michigan. Reserves have not been established yet. A third horizontal well, the State Springdale & Wilburn 1-21 HD has been drilled and is waiting on completion. Two more horizontal wells have been permitted in the Springdale area by our industry partner.

  17. Seismic Sounding of Convection in the Sun

    NASA Astrophysics Data System (ADS)

    Hanasoge, Shravan; Gizon, Laurent; Sreenivasan, Katepalli R.

    2016-01-01

    Thermal convection is the dominant mechanism of energy transport in the outer envelope of the Sun (one-third by radius). It drives global fluid circulations and magnetic fields observed on the solar surface. Vigorous surface convection excites a broadband spectrum of acoustic waves that propagate within the interior and set up modal resonances. These acoustic waves, also called seismic waves in this context, are observed at the surface of the Sun by space- and ground-based telescopes. Seismic sounding, the study of these seismic waves to infer the internal properties of the Sun, constitutes helioseismology. Here we review our knowledge of solar convection, especially that obtained through seismic inference. Several characteristics of solar convection, such as differential rotation, anisotropic Reynolds stresses, the influence of rotation on convection, and supergranulation, are considered. On larger scales, several inferences suggest that convective velocities are substantially smaller than those predicted by theory and simulations. This discrepancy challenges the models of internal differential rotation that rely on convective stresses as a driving mechanism and provide an important benchmark for numerical simulations.

  18. Seismic refraction analysis: the path forward

    USGS Publications Warehouse

    Haines, Seth S.; Zelt, Colin; Doll, William

    2012-01-01

    Seismic Refraction Methods: Unleashing the Potential and Understanding the Limitations; Tucson, Arizona, 29 March 2012 A workshop focused on seismic refraction methods took place on 29 May 2012, associated with the 2012 Symposium on the Application of Geophysics to Engineering and Environmental Problems. This workshop was convened to assess the current state of the science and discuss paths forward, with a primary focus on near-surface problems but with an eye on all applications. The agenda included talks on these topics from a number of experts interspersed with discussion and a dedicated discussion period to finish the day. Discussion proved lively at times, and workshop participants delved into many topics central to seismic refraction work.

  19. Seismic exploration for water on Mars

    NASA Technical Reports Server (NTRS)

    Page, Thornton

    1987-01-01

    It is proposed to soft-land three seismometers in the Utopia-Elysium region and three or more radio controlled explosive charges at nearby sites that can be accurately located by an orbiter. Seismic signatures of timed explosions, to be telemetered to the orbiter, will be used to detect present surface layers, including those saturated by volatiles such as water and/or ice. The Viking Landers included seismometers that showed that at present Mars is seismically quiet, and that the mean crustal thickness at the site is about 14 to 18 km. The new seismic landers must be designed to minimize wind vibration noise, and the landing sites selected so that each is well formed on the regolith, not on rock outcrops or in craters. The explosive charges might be mounted on penetrators aimed at nearby smooth areas. They must be equipped with radio emitters for accurate location and radio receivers for timed detonation.

  20. Evaluation of microindentation properties of epitaxial 3C-SiC/Si thin films

    NASA Astrophysics Data System (ADS)

    Geetha, D.; Sophia, P. Joice; Arivuoli, D.

    2016-06-01

    The microhardness characteristics of 3C-SiC/Si films grown by vapor phase epitaxy were investigated using Vickers and Knoop indenters. The observed hardness behavior at lower load range is being attributed to indentation size effect while the substrate hardness effect is found to be prominent at higher loads. The related mechanical properties such as fracture toughness, brittleness index, and yield stress were also evaluated. In order to study the nature and behavior of the surface topography during the deformation process for the applied load, detailed atomic force microscopy images were obtained around the indented regions of the samples. It revealed that the indents formed at higher loads showed fracture characteristics with a pattern of radial cracks propagating from the indent corners.

  1. 18 CFR 3c.3 - Reporting fraud, waste, abuse, and corruption and cooperation with official inquiries.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... OF CONDUCT § 3c.3 Reporting fraud, waste, abuse, and corruption and cooperation with official inquiries. (a) Employees shall, in fulfilling the obligation of 5 CFR 2635.101(b)(11), report fraud, waste..., abuse, and corruption and cooperation with official inquiries. 3c.3 Section 3c.3 Conservation of...

  2. 18 CFR 3c.3 - Reporting fraud, waste, abuse, and corruption and cooperation with official inquiries.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... OF CONDUCT § 3c.3 Reporting fraud, waste, abuse, and corruption and cooperation with official inquiries. (a) Employees shall, in fulfilling the obligation of 5 CFR 2635.101(b)(11), report fraud, waste..., abuse, and corruption and cooperation with official inquiries. 3c.3 Section 3c.3 Conservation of...

  3. 40 CFR 152.112 - Approval of registration under FIFRA sec. 3(c)(5).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... sec. 3(c)(5). 152.112 Section 152.112 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Applications § 152.112 Approval of registration under FIFRA sec. 3(c)(5). EPA will approve an application under the criteria of FIFRA sec. 3(c)(5) only if: (a) The Agency has determined that the application...

  4. Seismic Consequence Abstraction

    SciTech Connect

    M. Gross

    2004-10-25

    The primary purpose of this model report is to develop abstractions for the response of engineered barrier system (EBS) components to seismic hazards at a geologic repository at Yucca Mountain, Nevada, and to define the methodology for using these abstractions in a seismic scenario class for the Total System Performance Assessment - License Application (TSPA-LA). A secondary purpose of this model report is to provide information for criticality studies related to seismic hazards. The seismic hazards addressed herein are vibratory ground motion, fault displacement, and rockfall due to ground motion. The EBS components are the drip shield, the waste package, and the fuel cladding. The requirements for development of the abstractions and the associated algorithms for the seismic scenario class are defined in ''Technical Work Plan For: Regulatory Integration Modeling of Drift Degradation, Waste Package and Drip Shield Vibratory Motion and Seismic Consequences'' (BSC 2004 [DIRS 171520]). The development of these abstractions will provide a more complete representation of flow into and transport from the EBS under disruptive events. The results from this development will also address portions of integrated subissue ENG2, Mechanical Disruption of Engineered Barriers, including the acceptance criteria for this subissue defined in Section 2.2.1.3.2.3 of the ''Yucca Mountain Review Plan, Final Report'' (NRC 2003 [DIRS 163274]).

  5. Seismic offset balancing

    SciTech Connect

    Ross, C.P.; Beale, P.L.

    1994-01-01

    The ability to successfully predict lithology and fluid content from reflection seismic records using AVO techniques is contingent upon accurate pre-analysis conditioning of the seismic data. However, all too often, residual amplitude effects remain after the many offset-dependent processing steps are completed. Residual amplitude effects often represent a significant error when compared to the amplitude variation with offset (AVO) response that the authors are attempting to quantify. They propose a model-based, offset-dependent amplitude balancing method that attempts to correct for these residuals and other errors due to sub-optimal processing. Seismic offset balancing attempts to quantify the relationship between the offset response of back-ground seismic reflections and corresponding theoretical predictions for average lithologic interfaces thought to cause these background reflections. It is assumed that any deviation from the theoretical response is a result of residual processing phenomenon and/or suboptimal processing, and a simple offset-dependent scaling function is designed to correct for these differences. This function can then be applied to seismic data over both prospective and nonprospective zones within an area where the theoretical values are appropriate and the seismic characteristics are consistent. A conservative application of the above procedure results in an AVO response over both gas sands and wet sands that is much closer to theoretically expected values. A case history from the Gulf of Mexico Flexure Trend is presented as an example to demonstrate the offset balancing technique.

  6. Grail Refinements to Lunar Seismic Structure

    NASA Technical Reports Server (NTRS)

    Weber, Renee C.; Schmerr, N. C.

    2014-01-01

    To probe a planet's interior, seismology provides the most direct constraints on the variables that govern the dynamic properties of the body. However, the GRAIL (Gravity Recovery and Interior Laboratory) mission's high-resolution measurements of the lunar gravity field provide constraints on crustal thickness, mantle structure, core radius and stratification, and core state (solid vs. molten). These data complement seismic investigations, and joint interpretation permits improved constraints on the Moon's internal structure. Joint interpretation of disparate geophysical datasets helps reduce drawbacks that can result from analyzing them individually. The Apollo seismic network was situated on the lunar nearside surface in a roughly equilateral triangle having sides approximately 1000 km long, with stations 12/14 nearly co-located at one corner. Due to this limited geographical extent, near-surface ray coverage from moonquakes is low, but increase with depth. In comparison, gravity surveys and their resulting gravity anomaly maps have traditionally offered optimal resolution at crustal depths. Gravimetric maps and seismic data sets are therefor well suited to joint inversion, since the complementary information reduces inherent model ambiguity. We will perform a joint inversion of Apollo seismic delay times and gravity data collected by GRAIL lunar gravity mission, in order to recover seismic velocity and density as a function of latitude, longitude and depth within the Moon. We will relate density (rho) to seismic velocity (v) using a linear relationship that is allowed to be depth-dependent. The corresponding coefficient (B) can reflect a variety of material properties that vary with depth, including temperature and composition. The inversion seeks to recover the set of rho, v, and B perturbations that minimize (in a least-squares sense) the difference between the observed and calculated data.

  7. Seismicity and faulting attributable to fluid extraction

    USGS Publications Warehouse

    Yerkes, R.F.; Castle, R.O.

    1976-01-01

    The association between fluid injection and seismicity has been well documented and widely publicized. Less well known, but probably equally widespread are faulting and shallow seismicity attributable solely to fluid extraction, particularly in association with petroleum production. Two unequivocable examples of seismicity and faulting associated with fluid extraction in the United States are: The Goose Creek, Texas oil field event of 1925 (involving surface rupture); and the Wilmington, California oil field events (involving subsurface rupture) of 1947, 1949, 1951 (2), 1955, and 1961. Six additional cases of intensity I-VII earthquakes (M < 4.6) without reported faulting may be attributable to shallow production from other large oil and gas fields. In addition to these examples are thirteen cases of apparently aseismic surface rupture associated with production from California and Texas oil fields. Small earthquakes in the Eloy-Picacho area of Arizona may be attributable to withdrawal of groundwater, but their relation to widespread fissuring is enigmatic. The clearest example of extraction-induced seismicity outside of North America is the 1951 series of earthquakes associated with gas production from the Po River delta near Caviga, Italy. Faulting and seismicity associated with fluid extraction are attributed to differential compaction at depth caused by reduction of reservoir fluid pressure and attendant increase in effective stress. Surface and subsurface measurements and theoretical and model studies show that differential compaction leads not only to differential subsidence and centripetally-directed horizontal displacements, but to changes in both vertical- and horizontal-strain regimes. Study of well-documented examples indicates that the occurrence and nature of faulting and seismicity associated with compaction are functions chiefly of: (1) the pre-exploitation strain regime, and (2) the magnitude of contractional horizontal strain centered over the

  8. SURFACE RUPTURE OF THE NORMAL SEISMIC FAULTS AND SLOPE FAILURES APPEARED IN APRIL 11th, 2011 FUKUSHIMA-PREFECTURE HAMADOORI EARTHQUAKE

    NASA Astrophysics Data System (ADS)

    Kazmi, Zaheer Abbas; Konagai, Kazuo; Kyokawa, Hiroyuki; Tetik, Cigdem

    On April 11th, 2011, Iwaki region of Fukushima prefecture was jolted by Fukushima-Prefecture Hamadoori Earthquake. Surface ruptures were observed along causative Idosawa and Yunotake normal faults. In addition to numerous small slope failures, a coherent landslide and building structures of Tabito Junior High School, bisected by Idosawa Fault, were found along the causative faults. A precise digital elevation model of the coherent landslide was obtained through the ground and air-born LiDAR surveys. The measurements of perimeters of the gymnasium building and the swimming pool of Tabito Junior High School have shown that ground undergoes a slow and steady/continual deformation.

  9. Basic Data Report for Drillhole SNL-3 (C-2949)

    SciTech Connect

    Dennis W. Powers; Washington Regulatory and Environmental Services

    2005-01-20

    SNL-3 (permitted by the New Mexico State Engineer as C-2949) was drilled to provide geological data and hydrological testing of the Culebra Dolomite Member of the Permian Rustler Formation within a dissolution reentrant north of the WIPP site and well east of Livingston Ridge. SNL-3 is located in the southeast quarter of section 34, T21S, R31E, in eastern Eddy County, New Mexico. SNL-3 was drilled to a total depth of 970 ft below ground level (bgl). Below surface dune sand, SNL-3 encountered, in order, the Mescalero caliche, Gatuna, Dewey Lake, Rustler, and upper Salado Formations. Two intervals were cored: (1) from the lower Forty-niner Member through the Magenta Dolomite and into the upper Tamarisk Member; and (2) from the lower Tamarisk Member through the Culebra Dolomite and Los Meda?os Members and into the uppermost Salado.

  10. Seismic data from man-made impacts on the moon.

    PubMed

    Latham, G; Ewing, M; Dorman, J; Press, F; Toksoz, N; Sutton, G; Meissner, R; Duennebier, F; Nakamura, Y; Kovach, R; Yates, M

    1970-11-01

    Unusually long reverberations were recorded from two lunar impacts by a seismic station installed on the lunar surface by the Apollo 12 astronauts. Seismic data from these impacts suggest that the lunar mare in the region of the Apollo 12 landing site consists of material with very low seismic velocities near the surface, with velocity increasing with depth to 5 to 6 kilometers per second (for compressional waves) at a depth of 20 kilometers. Absorption of seismic waves in this structure is extremely low relative to typical continental crustal materials on earth. It is unlikely that a major boundary similar to the crustmantle interface on earth exists in the outer 20 kilometers of the moon. A combination of dispersion and scattering of surface waves probably explains the lunar seismic reverberation. Scattering of these waves implies the presence of heterogeneity within the outer zone of the mare on a scale of from several hundred meters (or less) to several kilometers. Seismic signals from 160 events of natural origin have been recorded during the first 7 months of operation of the Apollo 12 seismic station. At least 26 of the natural events are small moonquakes. Many of the natural events are thought to be meteoroid impacts.

  11. GRAIL Refinements to Lunar Seismic Structure

    NASA Technical Reports Server (NTRS)

    Weber, Renee; Gernero, Edward; Lin, Pei-Ying; Thorne, Michael; Schmerr, Nicholas; Han, Shin-Chan

    2012-01-01

    The present ]day internal structure of the Moon provides insight not only into its own formation and evolution, but also that of all rocky planetary bodies. The most direct way to probe a planet fs interior structure is through seismology. As part of the Apollo lunar missions, four seismometers were deployed on the nearside surface of the Moon between the years 1969 and 1972. These instruments operated continuously until 1977, forming the only substantial extraterrestrial seismic data set in existence. These data have been used to constrain various aspects of the seismic velocity and density structure of the Moon. Typical 1-D models recognize a 30-60 km thick crust overlying a nearly constant ]velocity mantle, and extend to a depth of approximately 1000 km, below which the lack of penetrating moonquake ray ]paths precludes the seismic determination of deeper structure. Previously, the lack of observed moonquakes from the far side of the Moon has been used to infer the presence of a highly attenuating (possibly molten) core. Indirect geophysical measurements such as moment of inertia, magnetic induction, lunar laser ranging, and elemental abundances of mare basalts also place varying constraints on core size and state. In combination with seismic studies, these indirect measurements have been used to arrive at a commonly accepted model of the Moon's deepest interior that includes a solid inner and fluid outer core, overlain by a partial melt boundary layer. We recently applied modern array seismology techniques to the Apollo data