Effect of vertical ground motion on earthquake-induced derailment of railway vehicles over simply-supported bridges

NASA Astrophysics Data System (ADS)

Jin, Zhibin; Pei, Shiling; Li, Xiaozhen; Liu, Hongyan; Qiang, Shizhong

2016-11-01

The running safety of railway vehicles on bridges can be negatively affected by earthquake events. This phenomenon has traditionally been investigated with only the lateral ground excitation component considered. This paper presented results from a numerical investigation on the contribution of vertical ground motion component to the derailment of vehicles on simply-supported bridges. A full nonlinear wheel-rail contact model was used in the investigation together with the Hertzian contact theory and nonlinear creepage theory, which allows the wheel to jump vertically and separate from the rail. The wheel-rail relative displacement was used as the criterion for derailment events. A total of 18 ground motion records were used in the analysis to account for the uncertainty of ground motions. The results showed that inclusion of vertical ground motion will likely increase the chance of derailment. It is recommended to include vertical ground motion component in earthquake induced derailment analysis to ensure conservative estimations. The derailment event on bridges was found to be more closely related to the deck acceleration rather than the ground acceleration.

Ground motions from induced earthquakes in Oklahoma and Kansas and the implications for seismic hazard

NASA Astrophysics Data System (ADS)

Moschetti, M. P.; Rennolet, S.; Thompson, E.; Yeck, W.; McNamara, D. E.; Herrmann, R. B.; Powers, P.; Hoover, S. M.

2016-12-01

Recent efforts to characterize the seismic hazard resulting from increased seismicity rates in Oklahoma and Kansas highlight the need for a regionalized ground motion characterization. To support these efforts, we measure and compile strong ground motions and compare these average ground motions intensity measures (IMs) with existing ground motion prediction equations (GMPEs). IMs are computed for available broadband and strong-motion records from M≥3 earthquakes occurring January 2009-April 2016, using standard strong motion processing guidelines. We verified our methods by comparing results from specific earthquakes to other standard procedures such as the USGS Shakemap system. The large number of records required an automated processing scheme, which was complicated by the extremely high rate of small-magnitude earthquakes 2014-2016. Orientation-independent IMs include peak ground motions (acceleration and velocity) and pseudo-spectral accelerations (5 percent damping, 0.1-10 s period). Metadata for the records included relocated event hypocenters. The database includes more than 160,000 records from about 3200 earthquakes. Estimates of the mean and standard deviation of the IMs are computed by distance binning at intervals of 2 km. Mean IMs exhibit a clear break in geometrical attenuation at epicentral distances of about 50-70 km, which is consistent with previous studies in the CEUS. Comparisons of these ground motions with modern GMPEs provide some insight into the relative IMs of induced earthquakes in Oklahoma and Kansas relative to the western U.S. and the central and eastern U.S. The site response for these stations is uncertain because very little is known about shallow seismic velocity in the region, and we make no attempt to correct observed IMs to a reference site conditions. At close distances, the observed IMs are lower than the predictions of the seed GMPEs of the NGA-East project (and about consistent with NGA-West-2 ground motions). This ground

Earthquake ground motion: Chapter 3

USGS Publications Warehouse

Luco, Nicolas; Kircher, Charles A.; Crouse, C. B.; Charney, Finley; Haselton, Curt B.; Baker, Jack W.; Zimmerman, Reid; Hooper, John D.; McVitty, William; Taylor, Andy

2016-01-01

Most of the effort in seismic design of buildings and other structures is focused on structural design. This chapter addresses another key aspect of the design process—characterization of earthquake ground motion into parameters for use in design. Section 3.1 describes the basis of the earthquake ground motion maps in the Provisions and in ASCE 7 (the Standard). Section 3.2 has examples for the determination of ground motion parameters and spectra for use in design. Section 3.3 describes site-specific ground motion requirements and provides example site-specific design and MCER response spectra and example values of site-specific ground motion parameters. Section 3.4 discusses and provides an example for the selection and scaling of ground motion records for use in various types of response history analysis permitted in the Standard.

Ground-motion parameters of the southwestern Indiana earthquake of 18 June 2002 and the disparity between the observed and predicted values

USGS Publications Warehouse

Street, R.; Wiegand, J.; Woolery, E.W.; Hart, P.

2005-01-01

The M 4.5 southwestern Indiana earthquake of 18 June 2002 triggered 46 blast monitors in Indiana, Illinois, and Kentucky. The resulting free-field particle velocity records, along with similar data from previous earthquakes in the study area, provide a clear standard for judging the reliability of current maps for predicting ground motions greater than 2 Hz in southwestern Indiana and southeastern Illinois. Peak horizontal accelerations and velocities, and 5% damped pseudo-accelerations for the earthquake, generally exceeded ground motions predicted for the top of the bedrock by factors of 2 or more, even after soil amplifications were taken into consideration. It is suggested, but not proven, that the low shear-wave velocity and weathered bedrock in the area are also amplifying the higher-frequency ground motions that have been repeatedly recorded by the blast monitors in the study area. It is also shown that there is a good correlation between the peak ground motions and 5% pseudo-accelerations recorded for the event, and the Modified Mercalli intensities interpreted for the event by the U.S. Geological Survey.

Near-Fault Strong Ground Motions during the 2016 Kumamoto, Japan, Earthquake

NASA Astrophysics Data System (ADS)

Iwata, T.; Asano, K.

2016-12-01

The 2016 Kumamoto mainshock (Mw7.0) produced a surface ruptured fault of about 20km long with maximum 2m offset, and identified as a surface ruptured event. Two strong motion records were observed near the surface ruptured fault at Mashiki town hall and Nishihara village hall. We investigated characteristics of those strong ground motions. As the acceleration records consisted of the baseline errors caused by nonzero initial acceleration and tilting of the accelerograph, we carefully removed the baseline errors (c.f. Chiu, 2001, Boore and Bommer, 2005) so as to obtain velocity and displacements. The observed permanent displacements were about 1.2m in horizontal direction and about 0.7m sinking in vertical direction at Mashiki town hall, and about 1.7m and 1.8m, respectively, at Nishihara village hall. Those permanent displacements almost coincide to results by GNSS and InSAR analysis (e.g., GSI, 2016). It takes about only 3 s to reach the permanent displacement. Somerville (2003) pointed out that ground motions from earthquakes producing large surface ruptures appeared to have systematically weaker ground motions than ground motions from earthquakes whose rupture were confined to the subsurface using the Ground Motion Prediction Equation (GMPE) for response spectra (Abrahamson and Silva, 1997). We calculated the response spectra of those records, compared them to the GMPE with the same manner and found two records were systematically larger than the expected from the GMPE in the period range of 0.3 s to 5 s. We need to re-consider the working hypothesis that the near-fault ground motions are weaker and to separate the near-fault and site effects on ground motions. Strong motions in the longer period range would be mainly caused by the near-fault (near-field term) effect.We used the acceleration data of the Kumamoto seismic intensity information network, provided by JMA.

Strong ground motion from the November 12, 2017, M 7.3 Kermanshah earthquake in western Iran

NASA Astrophysics Data System (ADS)

Babaie Mahani, Alireza; Kazemian, Javad

2018-05-01

In this paper, we analyzed the strong ground motion from the November 12, 2017, Kermanshah earthquake in western Iran with moment magnitude (M) of 7.3. Nonlinear and linear amplification of ground motion amplitudes were observed at stations with soft soil condition at hypocentral distances below and above 100 km, respectively. Observation of large ground motion amplitudes dominated with long-period pulses on the strike-normal component of the velocity time series suggests a right-lateral component of movement and propagation of rupture towards southeast. Comparison of the horizontal peak ground acceleration (PGA) from the M 7.3 earthquake with global PGA values showed a similar decay in ground motion amplitudes, although it seems that PGA from the M 7.3 Kermanshah earthquake is higher than global values for NEHRP site class B. We also found that the bracketed duration (D b) was higher in the velocity domain than in the acceleration domain for the same modified Mercalli intensity (MMI) threshold. For example, D b reached 30 s at the maximum PGA while it was 50 s at the maximum peak ground velocity above the threshold of MMI = 5. Although the standard design spectrum from Iranian Code of Practice for Seismic Resistant Design of Buildings (standard No. 2800) seems to include appropriate values for the design of structures with fundamental period of 1 s and higher, it is underestimated for near-field ground motions at lower periods.

Applicability of source scaling relations for crustal earthquakes to estimation of the ground motions of the 2016 Kumamoto earthquake

NASA Astrophysics Data System (ADS)

Irikura, Kojiro; Miyakoshi, Ken; Kamae, Katsuhiro; Yoshida, Kunikazu; Somei, Kazuhiro; Kurahashi, Susumu; Miyake, Hiroe

2017-01-01

ground motions obtained using the EGF method agree well with the observed motions in terms of acceleration, velocity, and displacement within the frequency range of 0.3-10 Hz. These findings indicate that the 2016 Kumamoto earthquake is a standard event that follows the scaling relationship of crustal earthquakes in Japan.

High-frequency ground motion amplification during the 2011 Tohoku earthquake explained by soil dilatancy

NASA Astrophysics Data System (ADS)

Roten, D.; Fäh, D.; Bonilla, L. F.

2013-05-01

Ground motions of the 2011 Tohoku earthquake recorded at Onahama port (Iwaki, Fukushima prefecture) rank among the highest accelerations ever observed, with the peak amplitude of the 3-D acceleration vector approaching 2g. The response of the site was distinctively non-linear, as indicated by the presence of horizontal acceleration spikes which have been linked to cyclic mobility during similar observations. Compared to records of weak ground motions, the response of the site during the Mw 9.1 earthquake was characterized by increased amplification at frequencies above 10 Hz and in peak ground acceleration. This behaviour contrasts with the more common non-linear response encountered at non-liquefiable sites, which results in deamplification at higher frequencies. We simulate propagation of SH waves through the dense sand deposit using a non-linear finite difference code that is capable of modelling the development of excess pore water pressure. Dynamic soil parameters are calibrated using a direct search method that minimizes the difference between observed and simulated acceleration envelopes and response spectra. The finite difference simulations yield surface acceleration time-series that are consistent with the observations in shape and amplitude, pointing towards soil dilatancy as a likely explanation for the high-frequency pulses recorded at Onahama port. The simulations also suggest that the occurrence of high-frequency spikes coincided with a rapid increase in pore water pressure in the upper part of the sand deposit between 145 and 170 s. This sudden increase is possibly linked to a burst of high-frequency energy from a large slip patch below the Iwaki region.

Strong ground motion prediction using virtual earthquakes.

PubMed

Denolle, M A; Dunham, E M; Prieto, G A; Beroza, G C

2014-01-24

Sedimentary basins increase the damaging effects of earthquakes by trapping and amplifying seismic waves. Simulations of seismic wave propagation in sedimentary basins capture this effect; however, there exists no method to validate these results for earthquakes that have not yet occurred. We present a new approach for ground motion prediction that uses the ambient seismic field. We apply our method to a suite of magnitude 7 scenario earthquakes on the southern San Andreas fault and compare our ground motion predictions with simulations. Both methods find strong amplification and coupling of source and structure effects, but they predict substantially different shaking patterns across the Los Angeles Basin. The virtual earthquake approach provides a new approach for predicting long-period strong ground motion.

Strong ground motions generated by earthquakes on creeping faults

USGS Publications Warehouse

Harris, Ruth A.; Abrahamson, Norman A.

2014-01-01

A tenet of earthquake science is that faults are locked in position until they abruptly slip during the sudden strain-relieving events that are earthquakes. Whereas it is expected that locked faults when they finally do slip will produce noticeable ground shaking, what is uncertain is how the ground shakes during earthquakes on creeping faults. Creeping faults are rare throughout much of the Earth's continental crust, but there is a group of them in the San Andreas fault system. Here we evaluate the strongest ground motions from the largest well-recorded earthquakes on creeping faults. We find that the peak ground motions generated by the creeping fault earthquakes are similar to the peak ground motions generated by earthquakes on locked faults. Our findings imply that buildings near creeping faults need to be designed to withstand the same level of shaking as those constructed near locked faults.

Acceleration spectra for subduction zone earthquakes

USGS Publications Warehouse

Boatwright, J.; Choy, G.L.

1989-01-01

We estimate the source spectra of shallow earthquakes from digital recordings of teleseismic P wave groups, that is, P+pP+sP, by making frequency dependent corrections for the attenuation and for the interference of the free surface. The correction for the interference of the free surface assumes that the earthquake radiates energy from a range of depths. We apply this spectral analysis to a set of 12 subduction zone earthquakes which range in size from Ms = 6.2 to 8.1, obtaining corrected P wave acceleration spectra on the frequency band from 0.01 to 2.0 Hz. Seismic moment estimates from surface waves and normal modes are used to extend these P wave spectra to the frequency band from 0.001 to 0.01 Hz. The acceleration spectra of large subduction zone earthquakes, that is, earthquakes whose seismic moments are greater than 1027 dyn cm, exhibit intermediate slopes where u(w)???w5/4 for frequencies from 0.005 to 0.05 Hz. For these earthquakes, spectral shape appears to be a discontinuous function of seismic moment. Using reasonable assumptions for the phase characteristics, we transform the spectral shape observed for large earthquakes into the time domain to fit Ekstrom's (1987) moment rate functions for the Ms=8.1 Michoacan earthquake of September 19, 1985, and the Ms=7.6 Michoacan aftershock of September 21, 1985. -from Authors

Stochastic ground-motion simulations for the 2016 Kumamoto, Japan, earthquake

NASA Astrophysics Data System (ADS)

Zhang, Long; Chen, Guangqi; Wu, Yanqiang; Jiang, Han

2016-11-01

On April 15, 2016, Kumamoto, Japan, was struck by a large earthquake sequence, leading to severe casualty and building damage. The stochastic finite-fault method based on a dynamic corner frequency has been applied to perform ground-motion simulations for the 2016 Kumamoto earthquake. There are 53 high-quality KiK-net stations available in the Kyushu region, and we employed records from all stations to determine region-specific source, path and site parameters. The calculated S-wave attenuation for the Kyushu region beneath the volcanic and non-volcanic areas can be expressed in the form of Q s = (85.5 ± 1.5) f 0.68±0.01 and Q s = (120 ± 5) f 0.64±0.05, respectively. The effects of lateral S-wave velocity and attenuation heterogeneities on the ground-motion simulations were investigated. Site amplifications were estimated using the corrected cross-spectral ratios technique. Zero-distance kappa filter was obtained to be the value of 0.0514 ± 0.0055 s, using the spectral decay method. The stress drop of the mainshock based on the USGS slip model was estimated optimally to have a value of 64 bars. Our finite-fault model with optimized parameters was validated through the good agreement of observations and simulations at all stations. The attenuation characteristics of the simulated peak ground accelerations were also successfully captured by the ground-motion prediction equations. Finally, the ground motions at two destructively damaged regions, Kumamoto Castle and Minami Aso village, were simulated. We conclude that the stochastic finite-fault method with well-determined parameters can reproduce the ground-motion characteristics of the 2016 Kumamoto earthquake in both the time and frequency domains. This work is necessary for seismic hazard assessment and mitigation.[Figure not available: see fulltext.

Another Look at Strong Ground Motion Accelerations and Stress Drop

NASA Astrophysics Data System (ADS)

Baltay, A.; Prieto, G.; Ide, S.; Hanks, T. C.; Beroza, G. C.

2010-12-01

The relationship between earthquake stress drop and ground motion acceleration is central to seismic hazard analysis. We revisit measurements of root-mean-square (RMS) acceleration, arms, using KikNet accelerometer data from Japan. We directly measure RMS and peak acceleration, and estimate both apparent stress and corner frequencies using the empirical Green’s function (eGf) coda method of Baltay et al. [2010]. We predict armsfrom corner frequency and stress drop following McGuire and Hanks [1980] to compare with measurements. The theoretical relationship does a good job of predicting observed arms. We use four earthquake sequences in Japan to investigate the source parameters and accelerations: the 2008 Iwate-Miyagi earthquake; the off-Kamaishi repeating sequence; and the 2004 and 2007 Niigata events. In each data set, we choose events that are nearly co-located so that the path term to any station is constant. Small events are used as empirical Green’s functions to correct for propagation effects. For all sequences, we find that the apparent stress averages ~1 MPa for most events. Corner frequencies are consistent with Mo-1/3 scaling. We find the ratio of stress drop and apparent stress to be 5, consistent with the theoretical derivation of Singh and Ordaz [1994], using a Brune [1970] spectra. armsis theoretically proportional to stress drop and the inverse square root of the corner frequency. We show that this calculation can be used as a proxy for armsobservations from strong motion records, using recent data from the four earthquake sequences mentioned above. Even for the Iwate-Miyagi mainshock, which experienced over 4 g’s of acceleration, we find that apparent stress, stress drop and corner frequency follow expected scaling laws and support self-similarity.

Widespread ground motion distribution caused by rupture directivity during the 2015 Gorkha, Nepal earthquake

NASA Astrophysics Data System (ADS)

Koketsu, Kazuki; Miyake, Hiroe; Guo, Yujia; Kobayashi, Hiroaki; Masuda, Tetsu; Davuluri, Srinagesh; Bhattarai, Mukunda; Adhikari, Lok Bijaya; Sapkota, Soma Nath

2016-06-01

The ground motion and damage caused by the 2015 Gorkha, Nepal earthquake can be characterized by their widespread distributions to the east. Evidence from strong ground motions, regional acceleration duration, and teleseismic waveforms indicate that rupture directivity contributed significantly to these distributions. This phenomenon has been thought to occur only if a strike-slip or dip-slip rupture propagates to a site in the along-strike or updip direction, respectively. However, even though the earthquake was a dip-slip faulting event and its source fault strike was nearly eastward, evidence for rupture directivity is found in the eastward direction. Here, we explore the reasons for this apparent inconsistency by performing a joint source inversion of seismic and geodetic datasets, and conducting ground motion simulations. The results indicate that the earthquake occurred on the underthrusting Indian lithosphere, with a low dip angle, and that the fault rupture propagated in the along-strike direction at a velocity just slightly below the S-wave velocity. This low dip angle and fast rupture velocity produced rupture directivity in the along-strike direction, which caused widespread ground motion distribution and significant damage extending far eastwards, from central Nepal to Mount Everest.

ARMA models for earthquake ground motions. Seismic safety margins research program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, M. K.; Kwiatkowski, J. W.; Nau, R. F.

1981-02-01

Four major California earthquake records were analyzed by use of a class of discrete linear time-domain processes commonly referred to as ARMA (Autoregressive/Moving-Average) models. It was possible to analyze these different earthquakes, identify the order of the appropriate ARMA model(s), estimate parameters, and test the residuals generated by these models. It was also possible to show the connections, similarities, and differences between the traditional continuous models (with parameter estimates based on spectral analyses) and the discrete models with parameters estimated by various maximum-likelihood techniques applied to digitized acceleration data in the time domain. The methodology proposed is suitable for simulatingmore » earthquake ground motions in the time domain, and appears to be easily adapted to serve as inputs for nonlinear discrete time models of structural motions. 60 references, 19 figures, 9 tables.« less

Analysis of the Source and Ground Motions from the 2017 M8.2 Tehuantepec and M7.1 Puebla Earthquakes

NASA Astrophysics Data System (ADS)

Melgar, D.; Sahakian, V. J.; Perez-Campos, X.; Quintanar, L.; Ramirez-Guzman, L.; Spica, Z.; Espindola, V. H.; Ruiz-Angulo, A.; Cabral-Cano, E.; Baltay, A.; Geng, J.

2017-12-01

The September 2017 Tehuantepec and Puebla earthquakes were intra-slab earthquakes that together caused significant damage in broad regions of Mexico, including the states of Oaxaca, Chiapas, Morelos, Puebla, Mexico, and Mexico City. Ground motions in Mexico City have approximately the same angle of incidence from both earthquakes and potentially sample similar paths close to the city. We examine site effects and source terms by analysis of residuals between Ground-Motion Prediction Equations (GMPEs) and observed ground motions for both of these events at stations from the Servicio Sismólogico Nacional, Instituto de Ingeniería, and the Instituto de Geofísica Red del Valle de Mexico networks. GMPEs are a basis for seismic design, but also provide median ground motion values to act as a basis for comparison of individual earthquakes and site responses. First, we invert for finite-fault slip inversions for Tehuantepec with high-rate GPS, static GPS, tide gauge and DART buoy data, and for Puebla with high-rate GPS and strong motion data. Using the distance from the stations with ground motion observations to the derived slip models, we use the GMPEs of Garcia et al. (2005), Zhao et al. (2006), and Abrahamson, Silva and Kamai (2014), to compute predicted values of peak ground acceleration and velocity (PGA and PGV) and response spectral accelerations (SA). Residuals between observed and predicted ground motion parameters are then computed for each recording, and are decomposed into event and site components using a mixed effects regression. We analyze these residuals as an adjustment away from median ground motions in the region to glean information about the earthquake source properties, as well as local site response in and outside of the Mexico City basin. The event and site terms are then compared with available values of stress drop for the two earthquakes, and Vs30 values for the sites, respectively. This analysis is useful in determining which GMPE is most

The ShakeOut earthquake source and ground motion simulations

USGS Publications Warehouse

Graves, R.W.; Houston, Douglas B.; Hudnut, K.W.

2011-01-01

The ShakeOut Scenario is premised upon the detailed description of a hypothetical Mw 7.8 earthquake on the southern San Andreas Fault and the associated simulated ground motions. The main features of the scenario, such as its endpoints, magnitude, and gross slip distribution, were defined through expert opinion and incorporated information from many previous studies. Slip at smaller length scales, rupture speed, and rise time were constrained using empirical relationships and experience gained from previous strong-motion modeling. Using this rupture description and a 3-D model of the crust, broadband ground motions were computed over a large region of Southern California. The largest simulated peak ground acceleration (PGA) and peak ground velocity (PGV) generally range from 0.5 to 1.0 g and 100 to 250 cm/s, respectively, with the waveforms exhibiting strong directivity and basin effects. Use of a slip-predictable model results in a high static stress drop event and produces ground motions somewhat higher than median level predictions from NGA ground motion prediction equations (GMPEs).

Three-dimensional ground-motion simulations of earthquakes for the Hanford area, Washington

USGS Publications Warehouse

Frankel, Arthur; Thorne, Paul; Rohay, Alan

2014-01-01

This report describes the results of ground-motion simulations of earthquakes using three-dimensional (3D) and one-dimensional (1D) crustal models conducted for the probabilistic seismic hazard assessment (PSHA) of the Hanford facility, Washington, under the Senior Seismic Hazard Analysis Committee (SSHAC) guidelines. The first portion of this report demonstrates that the 3D seismic velocity model for the area produces synthetic seismograms with characteristics (spectral response values, duration) that better match those of the observed recordings of local earthquakes, compared to a 1D model with horizontal layers. The second part of the report compares the response spectra of synthetics from 3D and 1D models for moment magnitude (M) 6.6–6.8 earthquakes on three nearby faults and for a dipping plane wave source meant to approximate regional S-waves from a Cascadia great earthquake. The 1D models are specific to each site used for the PSHA. The use of the 3D model produces spectral response accelerations at periods of 0.5–2.0 seconds as much as a factor of 4.5 greater than those from the 1D models for the crustal fault sources. The spectral accelerations of the 3D synthetics for the Cascadia plane-wave source are as much as a factor of 9 greater than those from the 1D models. The differences between the spectral accelerations for the 3D and 1D models are most pronounced for sites with thicker supra-basalt sediments and for stations with earthquakes on the Rattlesnake Hills fault and for the Cascadia plane-wave source.

Earthquake-induced ground failures in Italy from a reviewed database

NASA Astrophysics Data System (ADS)

Martino, S.; Prestininzi, A.; Romeo, R. W.

2013-05-01

A database (Italian acronym CEDIT) of earthquake-induced ground failures in Italy is presented, and the related content is analysed. The catalogue collects data regarding landslides, liquefaction, ground cracks, surface faulting and ground-level changes triggered by earthquakes of Mercalli intensity 8 or greater that occurred in the last millennium in Italy. As of January 2013, the CEDIT database has been available online for public use (URL: http://www.ceri.uniroma1.it/cn/index.do?id=230&page=55) and is presently hosted by the website of the Research Centre for Geological Risks (CERI) of the "Sapienza" University of Rome. Summary statistics of the database content indicate that 14% of the Italian municipalities have experienced at least one earthquake-induced ground failure and that landslides are the most common ground effects (approximately 45%), followed by ground cracks (32%) and liquefaction (18%). The relationships between ground effects and earthquake parameters such as seismic source energy (earthquake magnitude and epicentral intensity), local conditions (site intensity) and source-to-site distances are also analysed. The analysis indicates that liquefaction, surface faulting and ground-level changes are much more dependent on the earthquake source energy (i.e. magnitude) than landslides and ground cracks. In contrast, the latter effects are triggered at lower site intensities and greater epicentral distances than the other environmental effects.

Earthquake-induced ground failures in Italy from a reviewed database

NASA Astrophysics Data System (ADS)

Martino, S.; Prestininzi, A.; Romeo, R. W.

2014-04-01

A database (Italian acronym CEDIT) of earthquake-induced ground failures in Italy is presented, and the related content is analysed. The catalogue collects data regarding landslides, liquefaction, ground cracks, surface faulting and ground changes triggered by earthquakes of Mercalli epicentral intensity 8 or greater that occurred in the last millennium in Italy. As of January 2013, the CEDIT database has been available online for public use (http://www.ceri.uniroma1.it/cn/gis.jsp ) and is presently hosted by the website of the Research Centre for Geological Risks (CERI) of the Sapienza University of Rome. Summary statistics of the database content indicate that 14% of the Italian municipalities have experienced at least one earthquake-induced ground failure and that landslides are the most common ground effects (approximately 45%), followed by ground cracks (32%) and liquefaction (18%). The relationships between ground effects and earthquake parameters such as seismic source energy (earthquake magnitude and epicentral intensity), local conditions (site intensity) and source-to-site distances are also analysed. The analysis indicates that liquefaction, surface faulting and ground changes are much more dependent on the earthquake source energy (i.e. magnitude) than landslides and ground cracks. In contrast, the latter effects are triggered at lower site intensities and greater epicentral distances than the other environmental effects.

Equations for estimating horizontal response spectra and peak acceleration from western North American earthquakes: A summary of recent work

USGS Publications Warehouse

Boore, D.M.; Joyner, W.B.; Fumal, T.E.

1997-01-01

In this paper we summarize our recently-published work on estimating horizontal response spectra and peak acceleration for shallow earthquakes in western North America. Although none of the sets of coefficients given here for the equations are new, for the convenience of the reader and in keeping with the style of this special issue, we provide tables for estimating random horizontal-component peak acceleration and 5 percent damped pseudo-acceleration response spectra in terms of the natural, rather than common, logarithm of the ground-motion parameter. The equations give ground motion in terms of moment magnitude, distance, and site conditions for strike-slip, reverse-slip, or unspecified faulting mechanisms. Site conditions are represented by the shear velocity averaged over the upper 30 m, and recommended values of average shear velocity are given for typical rock and soil sites and for site categories used in the National Earthquake Hazards Reduction Program's recommended seismic code provisions. In addition, we stipulate more restrictive ranges of magnitude and distance for the use of our equations than in our previous publications. Finally, we provide tables of input parameters that include a few corrections to site classifications and earthquake magnitude (the corrections made a small enough difference in the ground-motion predictions that we chose not to change the coefficients of the prediction equations).

Decoupling the structure from the ground motion during earthquakes by employing friction pendulums

NASA Astrophysics Data System (ADS)

Gillich, G. R.; Iancu, V.; Gillich, N.; Korka, Z. I.; Chioncel, C. P.; Hatiegan, C.

2018-01-01

Avoiding dynamic loads on structures during earthquakes is an actual issue since seismic actions can harm or destroy the built environment. Several attempts to prevent this are possible, the essence being to decouple the structure from the ground motion during earthquakes and preventing in this way large deflections and high accelerations. A common approach is the use of friction pendulums, with cylindrical or spherical surfaces but not limited to that, inserted between the ground and the structure, respectively between the pillar and the superstructure. This type of bearings permits small pendulum motion and in this way, earthquake-induced displacements that occur in the bearings are not integrally transmitted to the structure. The consequence is that the structure is subject to greatly reduced lateral loads and shaking movements. In the experiments, conducted to prove the efficiency of the friction pendulums, we made use of an own designed and manufactured shaking table. Two types of sliding surfaces are analyzed, one polynomial of second order (i.e. circular) and one of a superior order. For both pendulum types, analytical models were developed. The results have shown that the structure is really decoupled from the ground motion and has a similar behaviour as that described by the analytic model.

Earthquake ground motion simulation at Zoser pyramid using the stochastic method: A step toward the preservation of an ancient Egyptian heritage

NASA Astrophysics Data System (ADS)

Khalil, Amin E.; Abdel Hafiez, H. E.; Girgis, Milad; Taha, M. A.

2017-06-01

Strong ground shaking during earthquakes can greatly affect the ancient monuments and subsequently demolish the human heritage. On October 12th 1992, a moderate earthquake (Ms = 5.8) shocked the greater Cairo area causing widespread damages. Unfortunately, the focus of that earthquake is located about 14 km to the south of Zoser pyramid. After the earthquake, the Egyptian Supreme council of antiquities issued an alarm that Zoser pyramid is partially collapsed and international and national efforts are exerted to restore this important human heritage that was built about 4000 years ago. Engineering and geophysical work is thus needed for the restoration process. The definition of the strong motion parameters is one of the required studies since seismically active zone is recorded in its near vicinity. The present study adopted the stochastic method to determine the peak ground motion (acceleration, velocity and displacement) for the three largest earthquakes recorded in the Egypt's seismological history. These earthquakes are Shedwan earthquake with magnitude Ms = 6.9, Aqaba earthquake with magnitude Mw = 7.2 and Cairo (Dahshour earthquake) with magnitude Ms = 5.8. The former two major earthquakes took place few hundred kilometers away. It is logic to have the predominant effects from the epicentral location of the Cairo earthquake; however, the authors wanted to test also the long period effects of the large distance earthquakes expected from the other two earthquakes under consideration. In addition, the dynamic site response was studied using the Horizontal to vertical spectral ratio (HVSR) technique. HVSR can provide information about the fundamental frequency successfully; however, the amplification estimation is not accepted. The result represented as either peak ground motion parameters or response spectra indicates that the effects from Cairo earthquake epicenter are the largest for all periods considered in the present study. The level of strong motion as

Strong ground motion in the Kathmandu Valley during the 2015 Gorkha, Nepal, earthquake

NASA Astrophysics Data System (ADS)

Takai, Nobuo; Shigefuji, Michiko; Rajaure, Sudhir; Bijukchhen, Subeg; Ichiyanagi, Masayoshi; Dhital, Megh Raj; Sasatani, Tsutomu

2016-01-01

On 25 April 2015, a large earthquake of Mw 7.8 occurred along the Main Himalayan Thrust fault in central Nepal. It was caused by a collision of the Indian Plate beneath the Eurasian Plate. The epicenter was near the Gorkha region, 80 km northwest of Kathmandu, and the rupture propagated toward east from the epicentral region passing through the sediment-filled Kathmandu Valley. This event resulted in over 8000 fatalities, mostly in Kathmandu and the adjacent districts. We succeeded in observing strong ground motions at our four observation sites (one rock site and three sedimentary sites) in the Kathmandu Valley during this devastating earthquake. While the observed peak ground acceleration values were smaller than the predicted ones that were derived from the use of a ground motion prediction equation, the observed peak ground velocity values were slightly larger than the predicted ones. The ground velocities observed at the rock site (KTP) showed a simple velocity pulse, resulting in monotonic-step displacements associated with the permanent tectonic offset. The vertical ground velocities observed at the sedimentary sites had the same pulse motions that were observed at the rock site. In contrast, the horizontal ground velocities as well as accelerations observed at three sedimentary sites showed long duration with conspicuous long-period oscillations, due to the valley response. The horizontal valley response was characterized by large amplification (about 10) and prolonged oscillations. However, the predominant period and envelope shape of their oscillations differed from site to site, indicating a complicated basin structure. Finally, on the basis of the velocity response spectra, we show that the horizontal long-period oscillations on the sedimentary sites had enough destructive power to damage high-rise buildings with natural periods of 3 to 5 s.

Using Modified Mercalli Intensities to estimate acceleration response spectra for the 1906 San Francisco earthquake

USGS Publications Warehouse

Boatwright, J.; Bundock, H.; Seekins, L.C.

2006-01-01

We derive and test relations between the Modified Mercalli Intensity (MMI) and the pseudo-acceleration response spectra at 1.0 and 0.3 s - SA(1.0 s) and SA(0.3 s) - in order to map response spectral ordinates for the 1906 San Francisco earthquake. Recent analyses of intensity have shown that MMI ??? 6 correlates both with peak ground velocity and with response spectra for periods from 0.5 to 3.0 s. We use these recent results to derive a linear relation between MMI and log SA(1.0 s), and we refine this relation by comparing the SA(1.0 s) estimated from Boatwright and Bundock's (2005) MMI map for the 1906 earthquake to the SA(1.0 s) calculated from recordings of the 1989 Loma Prieta earthquake. South of San Jose, the intensity distributions for the 1906 and 1989 earthquakes are remarkably similar, despite the difference in magnitude and rupture extent between the two events. We use recent strong motion regressions to derive a relation between SA(1.0 s) and SA(0.3 s) for a M7.8 strike-slip earthquake that depends on soil type, acceleration level, and source distance. We test this relation by comparing SA(0.3 s) estimated for the 1906 earthquake to SA(0.3 s) calculated from recordings of both the 1989 Loma Prieta and 1994 Northridge earthquakes, as functions of distance from the fault. ?? 2006, Earthquake Engineering Research Institute.

Ground-Motion Variability for a Strike-Slip Earthquake from Broadband Ground-Motion Simulations

NASA Astrophysics Data System (ADS)

Iwaki, A.; Maeda, T.; Morikawa, N.; Fujiwara, H.

2016-12-01

One of the important issues in seismic hazard analysis is the evaluation of ground-motion variability due to the epistemic and aleatory uncertainties in various aspects of ground-motion simulations. This study investigates the within-event ground-motion variability in broadband ground-motion simulations for strike-slip events. We conduct ground-motion simulations for a past event (2000 MW6.6 Tottori earthquake) using a set of characterized source models (e.g. Irikura and Miyake, 2011) considering aleatory variability. Broadband ground motion is computed by a hybrid approach that combines a 3D finite-difference method (> 1 s) and the stochastic Green's function method (< 1 s), using the 3D velocity model J-SHIS v2. We consider various locations of the asperities, which are defined as the regions with large slip and stress drop within the fault, and the rupture nucleation point (hypocenter). Ground motion records at 29 K-NET and KiK-net stations are used to validate our simulations. By comparing the simulated and observed ground motion, we found that the performance of the simulations is acceptable under the condition that the source parameters are poorly constrained. In addition to the observation stations, we set 318 virtual receivers with the spatial intervals of 10 km for statistical analysis of the simulated ground motion. The maximum fault-distance is 160 km. Standard deviation (SD) of the simulated acceleration response spectra (Sa, 5% damped) of RotD50 component (Boore, 2010) is investigated at each receiver. SD from 50 different patterns of asperity locations is generally smaller than 0.15 in terms of log10 (0.34 in natural log). It shows dependence on distance at periods shorter than 1 s; SD increases as the distance decreases. On the other hand, SD from 39 different hypocenter locations is again smaller than 0.15 in log10, and showed azimuthal dependence at long periods; it increases as the rupture directivity parameter Xcosθ(Somerville et al. 1997

Ground failure in the 2001 Mw 8.4 southern Peru earthquake

NASA Astrophysics Data System (ADS)

Rondinel-Oviedo, Efrain Alejandro

On June 23rd 2001 a moment magnitude (M W) 8.4, earthquake shook the southern portion of Peru. This rare large-magnitude event provided a unique opportunity to develop a suite of high quality case histories and also to test and calibrate existing geotechnical earthquake engineering analysis procedures and models against observations from the earthquake. The work presented in this thesis is focused on three topics pertaining to ground failure (i.e., the permanent deformation of the ground resulting from an earthquake) observed during the event: (1) surface ground damage in small basin geometries, (2) seismic compression, and (3) performance of a concrete faced rockfill dam (CFRD) dam. Surface ground strain damage patterns in small basin geometries has previously been typically studied at the large (i.e., geological) scale, but not at the scale of civil engineering infrastructure. During seismic events basin geometries containing soft material confined by stiffer material trap the seismic waves and generate surface waves that travel on the ground along the soft material. Numerical modeling shows that surface waves are generated at basin edges and travel on the ground creating higher duration, higher response (peak ground acceleration, PGA), higher energy (Arias Intensity) and higher angular distortion, especially in zones close to the edges. The impedance contrast between the stiff material and the soft material, and the dip angle play an important role in basin response. Seismic compression (i.e., the shaking induced densification of unsaturated soil) was observed in many highway embankments in the region of the earthquake. In many instances, this phenomenon was exasperated by soil-structure interaction with adjacent bridge or culvert structures. Numerical modeling conducted as part of this research showed (i) a significantly different response when the structure (culvert) is considered, (ii) impedance contrast plays a role in the system responses, and (iii) low

Sinking during earthquakes: Critical acceleration criteria control drained soil liquefaction

NASA Astrophysics Data System (ADS)

Clément, C.; Toussaint, R.; Stojanova, M.; Aharonov, E.

2018-02-01

This article focuses on liquefaction of saturated granular soils, triggered by earthquakes. Liquefaction is defined here as the transition from a rigid state, in which the granular soil layer supports structures placed on its surface, to a fluidlike state, in which structures placed initially on the surface sink to their isostatic depth within the granular layer. We suggest a simple theoretical model for soil liquefaction and show that buoyancy caused by the presence of water inside a granular medium has a dramatic influence on the stability of an intruder resting at the surface of the medium. We confirm this hypothesis by comparison with laboratory experiments and discrete-element numerical simulations. The external excitation representing ground motion during earthquakes is simulated via horizontal sinusoidal oscillations of controlled frequency and amplitude. In the experiments, we use particles only slightly denser than water, which as predicted theoretically increases the effect of liquefaction and allows clear depth-of-sinking measurements. In the simulations, a micromechanical model simulates grains using molecular dynamics with friction between neighbors. The effect of the fluid is captured by taking into account buoyancy effects on the grains when they are immersed. We show that the motion of an intruder inside a granular medium is mainly dependent on the peak acceleration of the ground motion and establish a phase diagram for the conditions under which liquefaction happens, depending on the soil bulk density, friction properties, presence of water, and peak acceleration of the imposed large-scale soil vibrations. We establish that in liquefaction conditions, most cases relax toward an equilibrium position following an exponential in time. We also show that the equilibrium position itself, for most liquefaction regimes, corresponds to the isostatic equilibrium of the intruder inside a medium of effective density. The characteristic time to relaxation is

Sinking during earthquakes: Critical acceleration criteria control drained soil liquefaction.

PubMed

Clément, C; Toussaint, R; Stojanova, M; Aharonov, E

2018-02-01

This article focuses on liquefaction of saturated granular soils, triggered by earthquakes. Liquefaction is defined here as the transition from a rigid state, in which the granular soil layer supports structures placed on its surface, to a fluidlike state, in which structures placed initially on the surface sink to their isostatic depth within the granular layer. We suggest a simple theoretical model for soil liquefaction and show that buoyancy caused by the presence of water inside a granular medium has a dramatic influence on the stability of an intruder resting at the surface of the medium. We confirm this hypothesis by comparison with laboratory experiments and discrete-element numerical simulations. The external excitation representing ground motion during earthquakes is simulated via horizontal sinusoidal oscillations of controlled frequency and amplitude. In the experiments, we use particles only slightly denser than water, which as predicted theoretically increases the effect of liquefaction and allows clear depth-of-sinking measurements. In the simulations, a micromechanical model simulates grains using molecular dynamics with friction between neighbors. The effect of the fluid is captured by taking into account buoyancy effects on the grains when they are immersed. We show that the motion of an intruder inside a granular medium is mainly dependent on the peak acceleration of the ground motion and establish a phase diagram for the conditions under which liquefaction happens, depending on the soil bulk density, friction properties, presence of water, and peak acceleration of the imposed large-scale soil vibrations. We establish that in liquefaction conditions, most cases relax toward an equilibrium position following an exponential in time. We also show that the equilibrium position itself, for most liquefaction regimes, corresponds to the isostatic equilibrium of the intruder inside a medium of effective density. The characteristic time to relaxation is

Pics d'accélération du mouvement sismique observés lors du séisme de Chichi à Taiwan : application à l'estimation de l'aléa sismiqueAnalysis of peak ground accelerations during the Chichi earthquake, Taiwan: application to seismic hazard evaluation

NASA Astrophysics Data System (ADS)

Chang, Tsui-Yu; Cotton, Fabrice; Angelier, Jacques; Shin, Tzay-Chyn

2001-07-01

Attenuation laws are widely used in order to estimate the peak ground acceleration that may occur at a given locality during an earthquake, for hazard evaluation purposes. However, these simplified laws should be regarded acceptable only in the first approximation, because numerous significant parameters at the local and regional scales are often ignored. We examined the relationship between distance and peak acceleration based on examples from the dense accelerometric network of Taiwan, specifically for the Chichi destructive earthquake. We thus observed significant discrepancies between the predicted and observed accelerations, resulting from (1) near-field saturation, (2) amplification in sedimentary basins, and (3) hanging wall effect. We mapped the residual accelerations (difference between observed and predicted peak ground accelerations). This highlights the role of the regional structure, independently revealed by the geological analysis, as a significant factor that controls the transmission of the seismic accelerations.

Magnitude Estimation for the 2011 Tohoku-Oki Earthquake Based on Ground Motion Prediction Equations

NASA Astrophysics Data System (ADS)

Eshaghi, Attieh; Tiampo, Kristy F.; Ghofrani, Hadi; Atkinson, Gail M.

2015-08-01

This study investigates whether real-time strong ground motion data from seismic stations could have been used to provide an accurate estimate of the magnitude of the 2011 Tohoku-Oki earthquake in Japan. Ultimately, such an estimate could be used as input data for a tsunami forecast and would lead to more robust earthquake and tsunami early warning. We collected the strong motion accelerograms recorded by borehole and free-field (surface) Kiban Kyoshin network stations that registered this mega-thrust earthquake in order to perform an off-line test to estimate the magnitude based on ground motion prediction equations (GMPEs). GMPEs for peak ground acceleration and peak ground velocity (PGV) from a previous study by Eshaghi et al. in the Bulletin of the Seismological Society of America 103. (2013) derived using events with moment magnitude ( M) ≥ 5.0, 1998-2010, were used to estimate the magnitude of this event. We developed new GMPEs using a more complete database (1998-2011), which added only 1 year but approximately twice as much data to the initial catalog (including important large events), to improve the determination of attenuation parameters and magnitude scaling. These new GMPEs were used to estimate the magnitude of the Tohoku-Oki event. The estimates obtained were compared with real time magnitude estimates provided by the existing earthquake early warning system in Japan. Unlike the current operational magnitude estimation methods, our method did not saturate and can provide robust estimates of moment magnitude within ~100 s after earthquake onset for both catalogs. It was found that correcting for average shear-wave velocity in the uppermost 30 m () improved the accuracy of magnitude estimates from surface recordings, particularly for magnitude estimates of PGV (Mpgv). The new GMPEs also were used to estimate the magnitude of all earthquakes in the new catalog with at least 20 records. Results show that the magnitude estimate from PGV values using

Source mechanism inversion and ground motion modeling of induced earthquakes in Kuwait - A Bayesian approach

NASA Astrophysics Data System (ADS)

Gu, C.; Toksoz, M. N.; Marzouk, Y.; Al-Enezi, A.; Al-Jeri, F.; Buyukozturk, O.

2016-12-01

The increasing seismic activity in the regions of oil/gas fields due to fluid injection/extraction and hydraulic fracturing has drawn new attention in both academia and industry. Source mechanism and triggering stress of these induced earthquakes are of great importance for understanding the physics of the seismic processes in reservoirs, and predicting ground motion in the vicinity of oil/gas fields. The induced seismicity data in our study are from Kuwait National Seismic Network (KNSN). Historically, Kuwait has low local seismicity; however, in recent years the KNSN has monitored more and more local earthquakes. Since 1997, the KNSN has recorded more than 1000 earthquakes (Mw < 5). In 2015, two local earthquakes - Mw4.5 in 03/21/2015 and Mw4.1 in 08/18/2015 - have been recorded by both the Incorporated Research Institutions for Seismology (IRIS) and KNSN, and widely felt by people in Kuwait. These earthquakes happen repeatedly in the same locations close to the oil/gas fields in Kuwait (see the uploaded image). The earthquakes are generally small (Mw < 5) and are shallow with focal depths of about 2 to 4 km. Such events are very common in oil/gas reservoirs all over the world, including North America, Europe, and the Middle East. We determined the location and source mechanism of these local earthquakes, with the uncertainties, using a Bayesian inversion method. The triggering stress of these earthquakes was calculated based on the source mechanisms results. In addition, we modeled the ground motion in Kuwait due to these local earthquakes. Our results show that most likely these local earthquakes occurred on pre-existing faults and were triggered by oil field activities. These events are generally smaller than Mw 5; however, these events, occurring in the reservoirs, are very shallow with focal depths less than about 4 km. As a result, in Kuwait, where oil fields are close to populated areas, these induced earthquakes could produce ground accelerations high

SITE AMPLIFICATION OF EARTHQUAKE GROUND MOTION.

USGS Publications Warehouse

Hays, Walter W.

1986-01-01

When analyzing the patterns of damage in an earthquake, physical parameters of the total earthquake-site-structure system are correlated with the damage. Soil-structure interaction, the cause of damage in many earthquakes, involves the frequency-dependent response of both the soil-rock column and the structure. The response of the soil-rock column (called site amplification) is controversial because soil has strain-dependent properties that affect the way the soil column filters the input body and surface seismic waves, modifying the amplitude and phase spectra and the duration of the surface ground motion.

Comparison of Ground Motion Prediction Equations (GMPE) for Chile and Canada With Recent Chilean Megathust Earthquakes

NASA Astrophysics Data System (ADS)

Herrera, C.; Cassidy, J. F.; Dosso, S. E.

2017-12-01

The ground shaking assessment allows quantifying the hazards associated with the occurrence of earthquakes. Chile and western Canada are two areas that have experienced, and are susceptible to imminent large crustal, in-slab and megathrust earthquakes that can affect the population significantly. In this context, we compare the current GMPEs used in the 2015 National Building Code of Canada and the most recent GMPEs calculated for Chile, with observed accelerations generated by four recent Chilean megathrust earthquakes (MW ≥ 7.7) that have occurred during the past decade, which is essential to quantify how well current models predict observations of major events.We collected the 3-component waveform data of more than 90 stations from the Centro Sismologico Nacional and the Universidad de Chile, and processed them by removing the trend and applying a band-pass filter. Then, for each station, we obtained the Peak Ground Acceleration (PGA), and by using a damped response spectra, we calculated the Pseudo Spectral Acceleration (PSA). Finally, we compared those observations with the most recent Chilean and Canadian GMPEs. Given the lack of geotechnical information for most of the Chilean stations, we also used a new method to obtain the VS30 by inverting the H/V ratios using a trans-dimensional Bayesian inversion, which allows us to improve the correction of observations according to soil conditions.As expected, our results show a good fit between observations and the Chilean GMPEs, but we observe that although the shape of the Canadian GMPEs is coherent with the distribution of observations, in general they under predict the observations for PGA and PSA at shorter periods for most of the considered earthquakes. An example of this can be seen in the attached figure for the case of the 2014 Iquique earthquake.These results present important implications related to the hazards associated to large earthquakes, especially for western Canada, where the probability of a

Assessment of Simulated Ground Motions in Earthquake Engineering Practice: A Case Study for Duzce (Turkey)

NASA Astrophysics Data System (ADS)

Karimzadeh, Shaghayegh; Askan, Aysegul; Yakut, Ahmet

2017-09-01

Simulated ground motions can be used in structural and earthquake engineering practice as an alternative to or to augment the real ground motion data sets. Common engineering applications of simulated motions are linear and nonlinear time history analyses of building structures, where full acceleration records are necessary. Before using simulated ground motions in such applications, it is important to assess those in terms of their frequency and amplitude content as well as their match with the corresponding real records. In this study, a framework is outlined for assessment of simulated ground motions in terms of their use in structural engineering. Misfit criteria are determined for both ground motion parameters and structural response by comparing the simulated values against the corresponding real values. For this purpose, as a case study, the 12 November 1999 Duzce earthquake is simulated using stochastic finite-fault methodology. Simulated records are employed for time history analyses of frame models of typical residential buildings. Next, the relationships between ground motion misfits and structural response misfits are studied. Results show that the seismological misfits around the fundamental period of selected buildings determine the accuracy of the simulated responses in terms of their agreement with the observed responses.

The limits of earthquake early warning: Timeliness of ground motion estimates

USGS Publications Warehouse

Minson, Sarah E.; Meier, Men-Andrin; Baltay, Annemarie S.; Hanks, Thomas C.; Cochran, Elizabeth S.

2018-01-01

The basic physics of earthquakes is such that strong ground motion cannot be expected from an earthquake unless the earthquake itself is very close or has grown to be very large. We use simple seismological relationships to calculate the minimum time that must elapse before such ground motion can be expected at a distance from the earthquake, assuming that the earthquake magnitude is not predictable. Earthquake early warning (EEW) systems are in operation or development for many regions around the world, with the goal of providing enough warning of incoming ground shaking to allow people and automated systems to take protective actions to mitigate losses. However, the question of how much warning time is physically possible for specified levels of ground motion has not been addressed. We consider a zero-latency EEW system to determine possible warning times a user could receive in an ideal case. In this case, the only limitation on warning time is the time required for the earthquake to evolve and the time for strong ground motion to arrive at a user’s location. We find that users who wish to be alerted at lower ground motion thresholds will receive more robust warnings with longer average warning times than users who receive warnings for higher ground motion thresholds. EEW systems have the greatest potential benefit for users willing to take action at relatively low ground motion thresholds, whereas users who set relatively high thresholds for taking action are less likely to receive timely and actionable information.

The limits of earthquake early warning: Timeliness of ground motion estimates

PubMed Central

Hanks, Thomas C.

2018-01-01

The basic physics of earthquakes is such that strong ground motion cannot be expected from an earthquake unless the earthquake itself is very close or has grown to be very large. We use simple seismological relationships to calculate the minimum time that must elapse before such ground motion can be expected at a distance from the earthquake, assuming that the earthquake magnitude is not predictable. Earthquake early warning (EEW) systems are in operation or development for many regions around the world, with the goal of providing enough warning of incoming ground shaking to allow people and automated systems to take protective actions to mitigate losses. However, the question of how much warning time is physically possible for specified levels of ground motion has not been addressed. We consider a zero-latency EEW system to determine possible warning times a user could receive in an ideal case. In this case, the only limitation on warning time is the time required for the earthquake to evolve and the time for strong ground motion to arrive at a user’s location. We find that users who wish to be alerted at lower ground motion thresholds will receive more robust warnings with longer average warning times than users who receive warnings for higher ground motion thresholds. EEW systems have the greatest potential benefit for users willing to take action at relatively low ground motion thresholds, whereas users who set relatively high thresholds for taking action are less likely to receive timely and actionable information. PMID:29750190

On the relation of earthquake stress drop and ground motion variability

NASA Astrophysics Data System (ADS)

Oth, Adrien; Miyake, Hiroe; Bindi, Dino

2017-07-01

One of the key parameters for earthquake source physics is stress drop since it can be directly linked to the spectral level of ground motion. Stress drop estimates from moment corner frequency analysis have been shown to be extremely variable, and this to a much larger degree than expected from the between-event ground motion variability. This discrepancy raises the question whether classically determined stress drop variability is too large, which would have significant consequences for seismic hazard analysis. We use a large high-quality data set from Japan with well-studied stress drop data to address this issue. Nonparametric and parametric reference ground motion models are derived, and the relation of between-event residuals for Japan Meteorological Agency equivalent seismic intensity and peak ground acceleration with stress drop is analyzed for crustal earthquakes. We find a clear correlation of the between-event residuals with stress drops estimates; however, while the island of Kyushu is characterized by substantially larger stress drops than Honshu, the between-event residuals do not reflect this observation, leading to the appearance of two event families with different stress drop levels yet similar range of between-event residuals. Both the within-family and between-family stress drop variations are larger than expected from the ground motion between-event variability. A systematic common analysis of these parameters holds the potential to provide important constraints on the relative robustness of different groups of data in the different parameter spaces and to improve our understanding on how much of the observed source parameter variability is likely to be true source physics variability.

Seismic hazard in Hawaii: High rate of large earthquakes and probabilistics ground-motion maps

USGS Publications Warehouse

Klein, F.W.; Frankel, A.D.; Mueller, C.S.; Wesson, R.L.; Okubo, P.G.

2001-01-01

The seismic hazard and earthquake occurrence rates in Hawaii are locally as high as that near the most hazardous faults elsewhere in the United States. We have generated maps of peak ground acceleration (PGA) and spectral acceleration (SA) (at 0.2, 0.3 and 1.0 sec, 5% critical damping) at 2% and 10% exceedance probabilities in 50 years. The highest hazard is on the south side of Hawaii Island, as indicated by the MI 7.0, MS 7.2, and MI 7.9 earthquakes, which occurred there since 1868. Probabilistic values of horizontal PGA (2% in 50 years) on Hawaii's south coast exceed 1.75g. Because some large earthquake aftershock zones and the geometry of flank blocks slipping on subhorizontal decollement faults are known, we use a combination of spatially uniform sources in active flank blocks and smoothed seismicity in other areas to model seismicity. Rates of earthquakes are derived from magnitude distributions of the modem (1959-1997) catalog of the Hawaiian Volcano Observatory's seismic network supplemented by the historic (1868-1959) catalog. Modern magnitudes are ML measured on a Wood-Anderson seismograph or MS. Historic magnitudes may add ML measured on a Milne-Shaw or Bosch-Omori seismograph or MI derived from calibrated areas of MM intensities. Active flank areas, which by far account for the highest hazard, are characterized by distributions with b slopes of about 1.0 below M 5.0 and about 0.6 above M 5.0. The kinked distribution means that large earthquake rates would be grossly under-estimated by extrapolating small earthquake rates, and that longer catalogs are essential for estimating or verifying the rates of large earthquakes. Flank earthquakes thus follow a semicharacteristic model, which is a combination of background seismicity and an excess number of large earthquakes. Flank earthquakes are geometrically confined to rupture zones on the volcano flanks by barriers such as rift zones and the seaward edge of the volcano, which may be expressed by a magnitude

Strong ground motion from the michoacan, Mexico, earthquake.

PubMed

Anderson, J G; Bodin, P; Brune, J N; Prince, J; Singh, S K; Quaas, R; Onate, M

1986-09-05

The network of strong motion accelerographs in Mexico includes instruments that were installed, under an international cooperative research program, in sites selected for the high potenial of a large earthquake. The 19 September 1985 earthquake (magnitude 8.1) occurred in a seismic gap where an earthquake was expected. As a result, there is an excellent descripton of the ground motions that caused the disaster.

Ground Motion Characteristics of Induced Earthquakes in Central North America

NASA Astrophysics Data System (ADS)

Atkinson, G. M.; Assatourians, K.; Novakovic, M.

2017-12-01

The ground motion characteristics of induced earthquakes in central North America are investigated based on empirical analysis of a compiled database of 4,000,000 digital ground-motion records from events in induced-seismicity regions (especially Oklahoma). Ground-motion amplitudes are characterized non-parametrically by computing median amplitudes and their variability in magnitude-distance bins. We also use inversion techniques to solve for regional source, attenuation and site response effects. Ground motion models are used to interpret the observations and compare the source and attenuation attributes of induced earthquakes to those of their natural counterparts. Significant conclusions are that the stress parameter that controls the strength of high-frequency radiation is similar for induced earthquakes (depth of h 5 km) and shallow (h 5 km) natural earthquakes. By contrast, deeper natural earthquakes (h 10 km) have stronger high-frequency ground motions. At distances close to the epicenter, a greater focal depth (which increases distance from the hypocenter) counterbalances the effects of a larger stress parameter, resulting in motions of similar strength close to the epicenter, regardless of event depth. The felt effects of induced versus natural earthquakes are also investigated using USGS "Did You Feel It?" reports; 400,000 reports from natural events and 100,000 reports from induced events are considered. The felt reports confirm the trends that we expect based on ground-motion modeling, considering the offsetting effects of the stress parameter versus focal depth in controlling the strength of motions near the epicenter. Specifically, felt intensity for a given magnitude is similar near the epicenter, on average, for all event types and depths. At distances more than 10 km from the epicenter, deeper events are felt more strongly than shallow events. These ground-motion attributes imply that the induced-seismicity hazard is most critical for facilities in

Dynamic fault rupture model of the 2008 Iwate-Miyagi Nairiku earthquake, Japan; Role of rupture velocity changes on extreme ground motions

NASA Astrophysics Data System (ADS)

Pulido Hernandez, N. E.; Dalguer Gudiel, L. A.; Aoi, S.

2009-12-01

The Iwate-Miyagi Nairiku earthquake, a reverse earthquake occurred in the southern Iwate prefecture Japan (2008/6/14), produced the largest peak ground acceleration recorded to date (4g) (Aoi et al. 2008), at the West Ichinoseki (IWTH25), KiK-net strong motion station of NIED. This station which is equipped with surface and borehole accelerometers (GL-260), also recorded very high peak accelerations up to 1g at the borehole level, despite being located in a rock site. From comparison of spectrograms of the observed surface and borehole records at IWTH25, Pulido et. al (2008) identified two high frequency (HF) ground motion events located at 4.5s and 6.3s originating at the source, which likely derived in the extreme observed accelerations of 3.9g and 3.5g at IWTH25. In order to understand the generation mechanism of these HF events we performed a dynamic fault rupture model of the Iwate-Miyagi Nairiku earthquake by using the Support Operator Rupture Dynamics (SORD) code, (Ely et al., 2009). SORD solves the elastodynamic equation using a generalized finite difference method that can utilize meshes of arbitrary structure and is capable of handling geometries appropriate to thrust earthquakes. Our spontaneous dynamic rupture model of the Iwate-Miyagi Nairiku earthquake is governed by the simple slip weakening friction law. The dynamic parameters, stress drop, strength excess and critical slip weakening distance are estimated following the procedure described in Pulido and Dalguer (2009) [PD09]. These parameters develop earthquake rupture consistent with the final slip obtained by kinematic source inversion of near source strong ground motion recordings. The dislocation model of this earthquake is characterized by a patch of large slip located ~7 km south of the hypocenter (Suzuki et al. 2009). Our results for the calculation of stress drop follow a similar pattern. Using the rupture times obtained from the dynamic model of the Iwate-Miyagi Nairiku earthquake we

Empirical relationships between instrumental ground motions and observed intensities for two great Chilean subduction zone earthquakes

NASA Astrophysics Data System (ADS)

Cilia, M. G.; Baker, L. M.

2015-12-01

We determine empirical relationships between instrumental peak ground motions and observed intensities for two great Chilean subduction earthquakes: the 2010 Mw8.8 Maule earthquake and the 2014 Mw8.2 Iquique earthquake. Both occurred immediately offshore on the primary plate boundary interface between the Nazca and South America plates. They are among the largest earthquakes to be instrumentally recorded; the 2010 Maule event is the second largest earthquake to produce strong motion recordings. Ground motion to intensity conversion equations (GMICEs) are used to reconstruct the distribution of shaking for historical earthquakes by using intensities estimated from contemporary accounts. Most great (M>8) earthquakes, like these, occur within subduction zones, yet few GMICEs exist for subduction earthquakes. It is unclear whether GMICEs developed for active crustal regions, such as California, can be scaled up to the large M of subduction zone events, or if new data sets must be analyzed to develop separate subduction GMICEs. To address this question, we pair instrumental peak ground motions, both acceleration (PGA) and velocity (PGV), with intensities derived from onsite surveys of earthquake damage made in the weeks after the events and internet-derived felt reports. We fit a linear predictive equation between the geometric mean of the maximum PGA or PGV of the two horizontal components and intensity, using linear least squares. We use a weighting scheme to express the uncertainty of the pairings based on a station's proximity to the nearest intensity observation. The intensity data derived from the onsite surveys is a complete, high-quality investigation of the earthquake damage. We perform the computations using both the survey data and community decimal intensities (CDI) calculated from felt reports volunteered by citizens (USGS "Did You Feel It", DYFI) and compare the results. We compare the GMICEs we developed to the most widely used GMICEs from California and

Earthquake response of storey building in Jakarta using accelerographs data analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Julius, Admiral Musa, E-mail: admiralmusajulius@yahoo.com; Jakarta Geophysics Observatory, Indonesia Agency of Meteorology Climatology and Geophysics; Sunardi, Bambang, E-mail: b.sunardi@gmail.com

As seismotectonic, the Jakarta city will be greatly affected by the earthquake which originated from the subduction zone of the Sunda Strait and south of Java. Some occurrences of earthquakes in these location are often perceived by the occupants in the upper floors of multi-storey buildings in Jakarta but was not perceived by the occupants on the ground floor. The case shows the difference in ground-motion parameters on each floor height. The analysis of the earthquake data recorded by accelerographs on different floors need to be done to know the differences in ground-motion parameters. Data used in this research ismore » accelerograph data installed on several floors in the main building of Meteorology Climatology and Geophysics Agency with a case study of Kebumen earthquake on January 25{sup th} 2014. Parameters analyzed include the Peak Ground Acceleration (PGA), Peak Ground Displacement (PGD), Peak Spectral Acceleration (PSA), Amplification (Ag), and the Effective Duration of earthquake (t{sub e}). Research stages include accelerographs data acquisition in three (3) different floors, conversion and data partition for each component, conversion to units of acceleration, determination of PGA, PGD, PSA, Ag and t{sub e} as well as data analysis. The study shows the value of PGA on the ground floor, 7{sup th} floor and 15{sup th} floors, respectively are 0.016 g, 0.053 g and 0.116 g. PGD on the ground floor, 7{sup th} floor and 15{sup th} floor respectively are 2.15 cm, 2.98 cm and 4.92 cm. PSA on the ground floor, 7{sup th} floor and 15{sup th} floor respectively are 0.067 g, 0.308 g and 0.836 g. Amplification of the peak acceleration value on the ground floor, 7{sup th} floor and 15{sup th} floor to the surface rock are 4.37, 6.07 and 7.30. Effective duration of the earthquake on the ground floor, 7{sup th} floor and 15{sup th} floor respectively are 222.28 s, 202.28 s and 91.58 s. In general, with increasing floor of the building, the value

Stochastic finite-fault simulation of ground motion from the August 11, 2012, M w 6.4 Ahar earthquake, northwestern Iran

NASA Astrophysics Data System (ADS)

Heidari, Reza

2016-04-01

In this study, the 11 August 2012 M w 6.4 Ahar earthquake is investigated using the ground motion simulation based on the stochastic finite-fault model. The earthquake occurred in northwestern Iran and causing extensive damage in the city of Ahar and surrounding areas. A network consisting of 58 acceleration stations recorded the earthquake within 8-217 km of the epicenter. Strong ground motion records from six significant well-recorded stations close to the epicenter have been simulated. These stations are installed in areas which experienced significant structural damage and humanity loss during the earthquake. The simulation is carried out using the dynamic corner frequency model of rupture propagation by extended fault simulation program (EXSIM). For this purpose, the propagation features of shear-wave including {Q}_s value, kappa value {k}_0 , and soil amplification coefficients at each site are required. The kappa values are obtained from the slope of smoothed amplitude of Fourier spectra of acceleration at higher frequencies. The determined kappa values for vertical and horizontal components are 0.02 and 0.05 s, respectively. Furthermore, an anelastic attenuation parameter is derived from energy decay of a seismic wave by using continuous wavelet transform (CWT) for each station. The average frequency-dependent relation estimated for the region is Q=(122± 38){f}^{(1.40± 0.16)}. Moreover, the horizontal to vertical spectral ratio H/V is applied to estimate the site effects at stations. Spectral analysis of the data indicates that the best match between the observed and simulated spectra occurs for an average stress drop of 70 bars. Finally, the simulated and observed results are compared with pseudo acceleration spectra and peak ground motions. The comparison of time series spectra shows good agreement between the observed and the simulated waveforms at frequencies of engineering interest.

Ground Motion Prediction Models for Caucasus Region

NASA Astrophysics Data System (ADS)

Jorjiashvili, Nato; Godoladze, Tea; Tvaradze, Nino; Tumanova, Nino

2016-04-01

Ground motion prediction models (GMPMs) relate ground motion intensity measures to variables describing earthquake source, path, and site effects. Estimation of expected ground motion is a fundamental earthquake hazard assessment. The most commonly used parameter for attenuation relation is peak ground acceleration or spectral acceleration because this parameter gives useful information for Seismic Hazard Assessment. Since 2003 development of Georgian Digital Seismic Network has started. In this study new GMP models are obtained based on new data from Georgian seismic network and also from neighboring countries. Estimation of models is obtained by classical, statistical way, regression analysis. In this study site ground conditions are additionally considered because the same earthquake recorded at the same distance may cause different damage according to ground conditions. Empirical ground-motion prediction models (GMPMs) require adjustment to make them appropriate for site-specific scenarios. However, the process of making such adjustments remains a challenge. This work presents a holistic framework for the development of a peak ground acceleration (PGA) or spectral acceleration (SA) GMPE that is easily adjustable to different seismological conditions and does not suffer from the practical problems associated with adjustments in the response spectral domain.

Toward resolving an earthquake ground motion mystery in west Seattle, Washington State: Shallow seismic focusing may cause anomalous chimney damage

USGS Publications Warehouse

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

2006-01-01

A shallow bedrock fold imaged by a 1.3-km long high-resolution shear-wave seismic reflection profile in west Seattle focuses seismic waves arriving from the south. This focusing may cause a pocket of amplified ground shaking and the anomalous chimney damage observed in earthquakes of 1949, 1965 and 2001. The 200-m bedrock fold at ???300-m depth is caused by deformation across an inferred fault within the Seattle fault zone. Ground motion simulations, using the imaged geologic structure and northward-propagating north-dipping plane wave sources, predict a peak horizontal acceleration pattern that matches that observed in strong motion records of the 2001 Nisqually event. Additionally, a pocket of chimney damage reported for both the 1965 and the 2001 earthquakes generally coincides with a zone of simulated amplification caused by focusing. This study further demonstrates the significant impact shallow (<1km) crustal structures can have on earthquake ground-motion variability.

Spatial correlation of probabilistic earthquake ground motion and loss

USGS Publications Warehouse

Wesson, R.L.; Perkins, D.M.

2001-01-01

Spatial correlation of annual earthquake ground motions and losses can be used to estimate the variance of annual losses to a portfolio of properties exposed to earthquakes A direct method is described for the calculations of the spatial correlation of earthquake ground motions and losses. Calculations for the direct method can be carried out using either numerical quadrature or a discrete, matrix-based approach. Numerical results for this method are compared with those calculated from a simple Monte Carlo simulation. Spatial correlation of ground motion and loss is induced by the systematic attenuation of ground motion with distance from the source, by common site conditions, and by the finite length of fault ruptures. Spatial correlation is also strongly dependent on the partitioning of the variability, given an event, into interevent and intraevent components. Intraevent variability reduces the spatial correlation of losses. Interevent variability increases spatial correlation of losses. The higher the spatial correlation, the larger the variance in losses to a port-folio, and the more likely extreme values become. This result underscores the importance of accurately determining the relative magnitudes of intraevent and interevent variability in ground-motion studies, because of the strong impact in estimating earthquake losses to a portfolio. The direct method offers an alternative to simulation for calculating the variance of losses to a portfolio, which may reduce the amount of calculation required.

Update of the Graizer-Kalkan ground-motion prediction equations for shallow crustal continental earthquakes

USGS Publications Warehouse

Graizer, Vladimir; Kalkan, Erol

2015-01-01

A ground-motion prediction equation (GMPE) for computing medians and standard deviations of peak ground acceleration and 5-percent damped pseudo spectral acceleration response ordinates of maximum horizontal component of randomly oriented ground motions was developed by Graizer and Kalkan (2007, 2009) to be used for seismic hazard analyses and engineering applications. This GMPE was derived from the greatly expanded Next Generation of Attenuation (NGA)-West1 database. In this study, Graizer and Kalkan’s GMPE is revised to include (1) an anelastic attenuation term as a function of quality factor (Q0) in order to capture regional differences in large-distance attenuation and (2) a new frequency-dependent sedimentary-basin scaling term as a function of depth to the 1.5-km/s shear-wave velocity isosurface to improve ground-motion predictions for sites on deep sedimentary basins. The new model (GK15), developed to be simple, is applicable to the western United States and other regions with shallow continental crust in active tectonic environments and may be used for earthquakes with moment magnitudes 5.0–8.0, distances 0–250 km, average shear-wave velocities 200–1,300 m/s, and spectral periods 0.01–5 s. Directivity effects are not explicitly modeled but are included through the variability of the data. Our aleatory variability model captures inter-event variability, which decreases with magnitude and increases with distance. The mixed-effects residuals analysis shows that the GK15 reveals no trend with respect to the independent parameters. The GK15 is a significant improvement over Graizer and Kalkan (2007, 2009), and provides a demonstrable, reliable description of ground-motion amplitudes recorded from shallow crustal earthquakes in active tectonic regions over a wide range of magnitudes, distances, and site conditions.

Strong Ground Motion Generation during the 2011 Tohoku-Oki Earthquake

NASA Astrophysics Data System (ADS)

Asano, K.; Iwata, T.

2011-12-01

Strong ground motions during the 2011 Tohoku-Oki earthquake (Mw9.0) were densely observed by the strong motion observation networks all over Japan. Seeing the acceleration and velocity waveforms observed at strong stations in northeast Japan along the source region, those ground motions are characterized by plural wave packets with duration of about twenty seconds. Particularly, two wave packets separated by about fifty seconds could be found on the records in the northern part of the damaged area, whereas only one significant wave packets could be recognized on the records in the southern part of the damaged area. The record section shows four isolated wave packets propagating from different locations to north and south, and it gives us a hint of the strong motion generation process on the source fault which is related to the heterogeneous rupture process in the scale of tens of kilometers. In order to solve it, we assume that each isolated wave packet is contributed by the corresponding strong motion generation area (SMGA). It is a source patch whose slip velocity is larger than off the area (Miyake et al., 2003). That is, the source model of the 2011 Tohoku-Oki earthquake consists of four SMGAs. The SMGA source model has succeeded in reproducing broadband strong ground motions for past subduction-zone events (e.g., Suzuki and Iwata, 2007). The target frequency range is set to be 0.1-10 Hz in this study as this range is significantly related to seismic damage generation to general man-made structures. First, we identified the rupture starting points of each SMGA by picking up the onset of individual packets. The source fault plane is set following the GCMT solution. The first two SMGAs were located approximately 70 km and 30 km west of the hypocenter. The third and forth SMGAs were located approximately 160 km and 230 km southwest of the hypocenter. Then, the model parameters (size, rise time, stress drop, rupture velocity, rupture propagation pattern) of these

Simulation of strong ground motion parameters of the 1 June 2013 Gulf of Suez earthquake, Egypt

NASA Astrophysics Data System (ADS)

Toni, Mostafa

2017-06-01

This article aims to simulate the ground motion parameters of the moderate magnitude (ML 5.1) June 1, 2013 Gulf of Suez earthquake, which represents the largest instrumental earthquake to be recorded in the middle part of the Gulf of Suez up to now. This event was felt in all cities located on both sides of the Gulf of Suez, with minor damage to property near the epicenter; however, no casualties were observed. The stochastic technique with the site-dependent spectral model is used to simulate the strong ground motion parameters of this earthquake in the cities located at the western side of the Gulf of Suez and north Red Sea namely: Suez, Ain Sokhna, Zafarana, Ras Gharib, and Hurghada. The presence of many tourist resorts and the increase in land use planning in the considered cities represent the motivation of the current study. The simulated parameters comprise the Peak Ground Acceleration (PGA), Peak Ground Velocity (PGV), and Peak Ground Displacement (PGD), in addition to Pseudo Spectral Acceleration (PSA). The model developed for ground motion simulation is validated by using the recordings of three accelerographs installed around the epicenter of the investigated earthquake. Depending on the site effect that has been determined in the investigated areas by using geotechnical data (e.g., shear wave velocities and microtremor recordings), the investigated areas are classified into two zones (A and B). Zone A is characterized by higher site amplification than Zone B. The ground motion parameters are simulated at each zone in the considered areas. The results reveal that the highest values of PGA, PGV, and PGD are observed at Ras Gharib city (epicentral distance ∼ 11 km) as 67 cm/s2, 2.53 cm/s, and 0.45 cm respectively for Zone A, and as 26.5 cm/s2, 1.0 cm/s, and 0.2 cm respectively for Zone B, while the lowest values of PGA, PGV, and PGD are observed at Suez city (epicentral distance ∼ 190 km) as 3.0 cm/s2, 0.2 cm/s, and 0.05 cm/s respectively for Zone A

Losses to single-family housing from ground motions in the 1994 Northridge, California, earthquake

USGS Publications Warehouse

Wesson, R.L.; Perkins, D.M.; Leyendecker, E.V.; Roth, R.J.; Petersen, M.D.

2004-01-01

The distributions of insured losses to single-family housing following the 1994 Northridge, California, earthquake for 234 ZIP codes can be satisfactorily modeled with gamma distributions. Regressions of the parameters in the gamma distribution on estimates of ground motion, derived from ShakeMap estimates or from interpolated observations, provide a basis for developing curves of conditional probability of loss given a ground motion. Comparison of the resulting estimates of aggregate loss with the actual aggregate loss gives satisfactory agreement for several different ground-motion parameters. Estimates of loss based on a deterministic spatial model of the earthquake ground motion, using standard attenuation relationships and NEHRP soil factors, give satisfactory results for some ground-motion parameters if the input ground motions are increased about one and one-half standard deviations above the median, reflecting the fact that the ground motions for the Northridge earthquake tended to be higher than the median ground motion for other earthquakes with similar magnitude. The results give promise for making estimates of insured losses to a similar building stock under future earthquake loading. ?? 2004, Earthquake Engineering Research Institute.

Empirical ground-motion relations for subduction-zone earthquakes and their application to Cascadia and other regions

USGS Publications Warehouse

Atkinson, G.M.; Boore, D.M.

2003-01-01

proposed for Cascadia and Japan. The results of this study differ significantly from previous analyses based on more limited data and have important implications for seismic-hazard analysis. The ground-motion relations predict that a great megathrust earthquake (M ???8) at a fault distance of about 100 km would produce pseudoacceleration (PSA), 5% damped, horizontal component on soil sites of about 110 cm/sec2 at 0.5 Hz, 660 cm/sec2 at 2.5 Hz, and 410 cm/sec2 at 5 Hz, with a peak ground acceleration of about 180 cm/ sec2 . These damaging levels of motion would be experienced over a very large area, corresponding to a rectangular area about 300 km wide by 500 km long. Large in-slab events (M 7.5) would produce even higher PSA values within 100 km of the fault, but the in-slab motions attenuate much more rapidly with distance. Thus the hazard posed by moderate to large in-slab events such as the 2001 Nisqually earthquake is modest compared to that of a Cascadia megathrust earthquake of M ???8, in terms of the area that would experience damaging levels of ground motion.

Ground motion modeling of the 1906 San Francisco earthquake II: Ground motion estimates for the 1906 earthquake and scenario events

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aagaard, B; Brocher, T; Dreger, D

2007-02-09

We estimate the ground motions produced by the 1906 San Francisco earthquake making use of the recently developed Song et al. (2008) source model that combines the available geodetic and seismic observations and recently constructed 3D geologic and seismic velocity models. Our estimates of the ground motions for the 1906 earthquake are consistent across five ground-motion modeling groups employing different wave propagation codes and simulation domains. The simulations successfully reproduce the main features of the Boatwright and Bundock (2005) ShakeMap, but tend to over predict the intensity of shaking by 0.1-0.5 modified Mercalli intensity (MMI) units. Velocity waveforms at sitesmore » throughout the San Francisco Bay Area exhibit characteristics consistent with rupture directivity, local geologic conditions (e.g., sedimentary basins), and the large size of the event (e.g., durations of strong shaking lasting tens of seconds). We also compute ground motions for seven hypothetical scenarios rupturing the same extent of the northern San Andreas fault, considering three additional hypocenters and an additional, random distribution of slip. Rupture directivity exerts the strongest influence on the variations in shaking, although sedimentary basins do consistently contribute to the response in some locations, such as Santa Rosa, Livermore, and San Jose. These scenarios suggest that future large earthquakes on the northern San Andreas fault may subject the current San Francisco Bay urban area to stronger shaking than a repeat of the 1906 earthquake. Ruptures propagating southward towards San Francisco appear to expose more of the urban area to a given intensity level than do ruptures propagating northward.« less

Implications of ground water chemistry and flow patterns for earthquake studies

USGS Publications Warehouse

Guangcai, W.; Zuochen, Z.; Min, W.; Cravotta, C.A.; Chenglong, L.

2005-01-01

Ground water can facilitate earthquake development and respond physically and chemically to tectonism. Thus, an understanding of ground water circulation in seismically active regions is important for earthquake prediction. To investigate the roles of ground water in the development and prediction of earthquakes, geological and hydrogeological monitoring was conducted in a seismogenic area in the Yanhuai Basin, China. This study used isotopic and hydrogeochemical methods to characterize ground water samples from six hot springs and two cold springs. The hydrochemical data and associated geological and geophysical data were used to identify possible relations between ground water circulation and seismically active structural features. The data for ??18O, ??D, tritium, and 14C indicate ground water from hot springs is of meteoric origin with subsurface residence times of 50 to 30,320 years. The reservoir temperature and circulation depths of the hot ground water are 57??C to 160??C and 1600 to 5000 m, respectively, as estimated by quartz and chalcedony geothermometers and the geothermal gradient. Various possible origins of noble gases dissolved in the ground water also were evaluated, indicating mantle and deep crust sources consistent with tectonically active segments. A hard intercalated stratum, where small to moderate earthquakes frequently originate, is present between a deep (10 to 20 km), high-electrical conductivity layer and the zone of active ground water circulation. The ground water anomalies are closely related to the structural peculiarity of each monitoring point. These results could have implications for ground water and seismic studies in other seismogenic areas. Copyright ?? 2005 National Ground Water Association.

Ground-motion modeling of the 1906 San Francisco Earthquake, part II: Ground-motion estimates for the 1906 earthquake and scenario events

USGS Publications Warehouse

Aagaard, Brad T.; Brocher, T.M.; Dolenc, D.; Dreger, D.; Graves, R.W.; Harmsen, S.; Hartzell, S.; Larsen, S.; McCandless, K.; Nilsson, S.; Petersson, N.A.; Rodgers, A.; Sjogreen, B.; Zoback, M.L.

2008-01-01

We estimate the ground motions produce by the 1906 San Francisco earthquake making use of the recently developed Song et al. (2008) source model that combines the available geodetic and seismic observations and recently constructed 3D geologic and seismic velocity models. Our estimates of the ground motions for the 1906 earthquake are consistent across five ground-motion modeling groups employing different wave propagation codes and simulation domains. The simulations successfully reproduce the main features of the Boatwright and Bundock (2005) ShakeMap, but tend to over predict the intensity of shaking by 0.1-0.5 modified Mercalli intensity (MMI) units. Velocity waveforms at sites throughout the San Francisco Bay Area exhibit characteristics consistent with rupture directivity, local geologic conditions (e.g., sedimentary basins), and the large size of the event (e.g., durations of strong shaking lasting tens of seconds). We also compute ground motions for seven hypothetical scenarios rupturing the same extent of the northern San Andreas fault, considering three additional hypocenters and an additional, random distribution of slip. Rupture directivity exerts the strongest influence on the variations in shaking, although sedimentary basins do consistently contribute to the response in some locations, such as Santa Rosa, Livermore, and San Jose. These scenarios suggest that future large earthquakes on the northern San Andreas fault may subject the current San Francisco Bay urban area to stronger shaking than a repeat of the 1906 earthquake. Ruptures propagating southward towards San Francisco appear to expose more of the urban area to a given intensity level than do ruptures propagating northward.

Effects of deep basins on structural collapse during large subduction earthquakes

USGS Publications Warehouse

Marafi, Nasser A.; Eberhard, Marc O.; Berman, Jeffrey W.; Wirth, Erin A.; Frankel, Arthur

2017-01-01

Deep sedimentary basins are known to increase the intensity of ground motions, but this effect is implicitly considered in seismic hazard maps used in U.S. building codes. The basin amplification of ground motions from subduction earthquakes is particularly important in the Pacific Northwest, where the hazard at long periods is dominated by such earthquakes. This paper evaluates the effects of basins on spectral accelerations, ground-motion duration, spectral shape, and structural collapse using subduction earthquake recordings from basins in Japan that have similar depths as the Puget Lowland basin. For three of the Japanese basins and the Puget Lowland basin, the spectral accelerations were amplified by a factor of 2 to 4 for periods above 2.0 s. The long-duration subduction earthquakes and the effects of basins on spectral shape combined, lower the spectral accelerations at collapse for a set of building archetypes relative to other ground motions. For the hypothetical case in which these motions represent the entire hazard, the archetypes would need to increase up to 3.3 times its strength to compensate for these effects.

Implications of ground water chemistry and flow patterns for earthquake studies.

PubMed

Guangcai, Wang; Zuochen, Zhang; Min, Wang; Cravotta, Charles A; Chenglong, Liu

2005-01-01

Ground water can facilitate earthquake development and respond physically and chemically to tectonism. Thus, an understanding of ground water circulation in seismically active regions is important for earthquake prediction. To investigate the roles of ground water in the development and prediction of earthquakes, geological and hydrogeological monitoring was conducted in a seismogenic area in the Yanhuai Basin, China. This study used isotopic and hydrogeochemical methods to characterize ground water samples from six hot springs and two cold springs. The hydrochemical data and associated geological and geophysical data were used to identify possible relations between ground water circulation and seismically active structural features. The data for delta18O, deltaD, tritium, and 14C indicate ground water from hot springs is of meteoric origin with subsurface residence times of 50 to 30,320 years. The reservoir temperature and circulation depths of the hot ground water are 57 degrees C to 160 degrees C and 1600 to 5000 m, respectively, as estimated by quartz and chalcedony geothermometers and the geothermal gradient. Various possible origins of noble gases dissolved in the ground water also were evaluated, indicating mantle and deep crust sources consistent with tectonically active segments. A hard intercalated stratum, where small to moderate earthquakes frequently originate, is present between a deep (10 to 20 km), high-electrical conductivity layer and the zone of active ground water circulation. The ground water anomalies are closely related to the structural peculiarity of each monitoring point. These results could have implications for ground water and seismic studies in other seismogenic areas.

Rapid acceleration leads to rapid weakening in earthquake-like laboratory experiments

USGS Publications Warehouse

Chang, Jefferson C.; Lockner, David A.; Reches, Z.

2012-01-01

After nucleation, a large earthquake propagates as an expanding rupture front along a fault. This front activates countless fault patches that slip by consuming energy stored in Earth’s crust. We simulated the slip of a fault patch by rapidly loading an experimental fault with energy stored in a spinning flywheel. The spontaneous evolution of strength, acceleration, and velocity indicates that our experiments are proxies of fault-patch behavior during earthquakes of moment magnitude (Mw) = 4 to 8. We show that seismically determined earthquake parameters (e.g., displacement, velocity, magnitude, or fracture energy) can be used to estimate the intensity of the energy release during an earthquake. Our experiments further indicate that high acceleration imposed by the earthquake’s rupture front quickens dynamic weakening by intense wear of the fault zone.

Source Model of Huge Subduction Earthquakes for Strong Ground Motion Prediction

NASA Astrophysics Data System (ADS)

Iwata, T.; Asano, K.

2012-12-01

It is a quite important issue for strong ground motion prediction to construct the source model of huge subduction earthquakes. Irikura and Miyake (2001, 2011) proposed the characterized source model for strong ground motion prediction, which consists of plural strong ground motion generation area (SMGA, Miyake et al., 2003) patches on the source fault. We obtained the SMGA source models for many events using the empirical Green's function method and found the SMGA size has an empirical scaling relationship with seismic moment. Therefore, the SMGA size can be assumed from that empirical relation under giving the seismic moment for anticipated earthquakes. Concerning to the setting of the SMGAs position, the information of the fault segment is useful for inland crustal earthquakes. For the 1995 Kobe earthquake, three SMGA patches are obtained and each Nojima, Suma, and Suwayama segment respectively has one SMGA from the SMGA modeling (e.g. Kamae and Irikura, 1998). For the 2011 Tohoku earthquake, Asano and Iwata (2012) estimated the SMGA source model and obtained four SMGA patches on the source fault. Total SMGA area follows the extension of the empirical scaling relationship between the seismic moment and the SMGA area for subduction plate-boundary earthquakes, and it shows the applicability of the empirical scaling relationship for the SMGA. The positions of two SMGAs are in Miyagi-Oki segment and those other two SMGAs are in Fukushima-Oki and Ibaraki-Oki segments, respectively. Asano and Iwata (2012) also pointed out that all SMGAs are corresponding to the historical source areas of 1930's. Those SMGAs do not overlap the huge slip area in the shallower part of the source fault which estimated by teleseismic data, long-period strong motion data, and/or geodetic data during the 2011 mainshock. This fact shows the huge slip area does not contribute to strong ground motion generation (10-0.1s). The information of the fault segment in the subduction zone, or

Validation of Broadband Ground Motion Simulations for Japanese Crustal Earthquakes by the Recipe

NASA Astrophysics Data System (ADS)

Iwaki, A.; Maeda, T.; Morikawa, N.; Miyake, H.; Fujiwara, H.

2015-12-01

The Headquarters for Earthquake Research Promotion (HERP) of Japan has organized the broadband ground motion simulation method into a standard procedure called the "recipe" (HERP, 2009). In the recipe, the source rupture is represented by the characterized source model (Irikura and Miyake, 2011). The broadband ground motion time histories are computed by a hybrid approach: the 3-D finite-difference method (Aoi et al. 2004) and the stochastic Green's function method (Dan and Sato, 1998; Dan et al. 2000) for the long- (> 1　s) and short-period (< 1 s) components, respectively, using the 3-D velocity structure model. As the engineering significance of scenario earthquake ground motion prediction is increasing, thorough verification and validation are required for the simulation methods. This study presents the self-validation of the recipe for two MW6.6 crustal events in Japan, the 2000 Tottori and 2004 Chuetsu (Niigata) earthquakes. We first compare the simulated velocity time series with the observation. Main features of the velocity waveforms, such as the near-fault pulses and the large later phases on deep sediment sites are well reproduced by the simulations. Then we evaluate 5% damped pseudo acceleration spectra (PSA) in the framework of the SCEC Broadband Platform (BBP) validation (Dreger et al. 2015). The validation results are generally acceptable in the period range 0.1 - 10 s, whereas those in the shortest period range (0.01-0.1 s) are less satisfactory. We also evaluate the simulations with the 1-D velocity structure models used in the SCEC BBP validation exercise. Although the goodness-of-fit parameters for PSA do not significantly differ from those for the 3-D velocity structure model, noticeable differences in velocity waveforms are observed. Our results suggest the importance of 1) well-constrained 3-D velocity structure model for broadband ground motion simulations and 2) evaluation of time series of ground motion as well as response spectra.

Accelerated nucleation of the 2014 Iquique, Chile Mw 8.2 Earthquake.

PubMed

Kato, Aitaro; Fukuda, Jun'ichi; Kumazawa, Takao; Nakagawa, Shigeki

2016-04-25

The earthquake nucleation process has been vigorously investigated based on geophysical observations, laboratory experiments, and theoretical studies; however, a general consensus has yet to be achieved. Here, we studied nucleation process for the 2014 Iquique, Chile Mw 8.2 megathrust earthquake located within the current North Chile seismic gap, by analyzing a long-term earthquake catalog constructed from a cross-correlation detector using continuous seismic data. Accelerations in seismicity, the amount of aseismic slip inferred from repeating earthquakes, and the background seismicity, accompanied by an increasing frequency of earthquake migrations, started around 270 days before the mainshock at locations up-dip of the largest coseismic slip patch. These signals indicate that repetitive sequences of fast and slow slip took place on the plate interface at a transition zone between fully locked and creeping portions. We interpret that these different sliding modes interacted with each other and promoted accelerated unlocking of the plate interface during the nucleation phase.

Accelerated nucleation of the 2014 Iquique, Chile Mw 8.2 Earthquake

NASA Astrophysics Data System (ADS)

Kato, Aitaro; Fukuda, Jun'Ichi; Kumazawa, Takao; Nakagawa, Shigeki

2016-04-01

The earthquake nucleation process has been vigorously investigated based on geophysical observations, laboratory experiments, and theoretical studies; however, a general consensus has yet to be achieved. Here, we studied nucleation process for the 2014 Iquique, Chile Mw 8.2 megathrust earthquake located within the current North Chile seismic gap, by analyzing a long-term earthquake catalog constructed from a cross-correlation detector using continuous seismic data. Accelerations in seismicity, the amount of aseismic slip inferred from repeating earthquakes, and the background seismicity, accompanied by an increasing frequency of earthquake migrations, started around 270 days before the mainshock at locations up-dip of the largest coseismic slip patch. These signals indicate that repetitive sequences of fast and slow slip took place on the plate interface at a transition zone between fully locked and creeping portions. We interpret that these different sliding modes interacted with each other and promoted accelerated unlocking of the plate interface during the nucleation phase.

Accelerated nucleation of the 2014 Iquique, Chile Mw 8.2 Earthquake

PubMed Central

Kato, Aitaro; Fukuda, Jun’ichi; Kumazawa, Takao; Nakagawa, Shigeki

2016-01-01

The earthquake nucleation process has been vigorously investigated based on geophysical observations, laboratory experiments, and theoretical studies; however, a general consensus has yet to be achieved. Here, we studied nucleation process for the 2014 Iquique, Chile Mw 8.2 megathrust earthquake located within the current North Chile seismic gap, by analyzing a long-term earthquake catalog constructed from a cross-correlation detector using continuous seismic data. Accelerations in seismicity, the amount of aseismic slip inferred from repeating earthquakes, and the background seismicity, accompanied by an increasing frequency of earthquake migrations, started around 270 days before the mainshock at locations up-dip of the largest coseismic slip patch. These signals indicate that repetitive sequences of fast and slow slip took place on the plate interface at a transition zone between fully locked and creeping portions. We interpret that these different sliding modes interacted with each other and promoted accelerated unlocking of the plate interface during the nucleation phase. PMID:27109362

Continuous estimates on the earthquake early warning magnitude by use of the near-field acceleration records

NASA Astrophysics Data System (ADS)

Li, Jun; Jin, Xing; Wei, Yongxiang; Zhang, Hongcai

2013-10-01

In this article, the seismic records of Japan's Kik-net are selected to measure the acceleration, displacement, and effective peak acceleration of each seismic record within a certain time after P wave, then a continuous estimation is given on earthquake early warning magnitude through statistical analysis method, and Wenchuan earthquake record is utilized to check the method. The results show that the reliability of earthquake early warning magnitude continuously increases with the increase of the seismic information, the biggest residual happens if the acceleration is adopted to fit earthquake magnitude, which may be caused by rich high-frequency components and large dispersion of peak value in acceleration record, the influence caused by the high-frequency components can be effectively reduced if the effective peak acceleration and peak displacement is adopted, it is estimated that the dispersion of earthquake magnitude obviously reduces, but it is easy for peak displacement to be affected by long-period drifting. In various components, the residual enlargement phenomenon at vertical direction is almost unobvious, thus it is recommended in this article that the effective peak acceleration at vertical direction is preferred to estimate earthquake early warning magnitude. Through adopting Wenchuan strong earthquake record to check the method mentioned in this article, it is found that this method can be used to quickly, stably, and accurately estimate the early warning magnitude of this earthquake, which shows that this method is completely applicable for earthquake early warning.

Data Files for Ground-Motion Simulations of the 1906 San Francisco Earthquake and Scenario Earthquakes on the Northern San Andreas Fault

USGS Publications Warehouse

Aagaard, Brad T.; Barall, Michael; Brocher, Thomas M.; Dolenc, David; Dreger, Douglas; Graves, Robert W.; Harmsen, Stephen; Hartzell, Stephen; Larsen, Shawn; McCandless, Kathleen; Nilsson, Stefan; Petersson, N. Anders; Rodgers, Arthur; Sjogreen, Bjorn; Zoback, Mary Lou

2009-01-01

This data set contains results from ground-motion simulations of the 1906 San Francisco earthquake, seven hypothetical earthquakes on the northern San Andreas Fault, and the 1989 Loma Prieta earthquake. The bulk of the data consists of synthetic velocity time-histories. Peak ground velocity on a 1/60th degree grid and geodetic displacements from the simulations are also included. Details of the ground-motion simulations and analysis of the results are discussed in Aagaard and others (2008a,b).

The September 19, 1985 Michoacan Earthquake: Aftershock acceleration data recorded by a temporary installation of strong motion instruments

NASA Astrophysics Data System (ADS)

Munguía, Luis; Simila, Gerry W.; McNally, Karen C.; Thompson, Howard

1986-06-01

We describe acceleration signals recorded for nine aftershocks of the September 19, 1985 Michoacan earthquake. To obtain this data set, three A-700 Teledyne-Geotech digital strong-motion instruments were operated temporarily at two sites on the José María Morelos (La Villita) Dam, and at a site located at about 12 km to the west of the town of Zihuatanejo. Peak horizontal accelerations of 0.005 g to 0.031 g were recorded at epicentral distances between 10 and 75 km, for earthquakes with magnitude (mb) between 4.5 and 5.3. It was observed that the peak accelerations recorded at a site on the embankment of the dam (near the crest ) are approximately three times those recorded on the abutment bedrock portion of the dam. Although these sites were spatially separated by no more than 300 m, differences among their records are also significant. Waveforms recorded at the embankment site look more complex than those from the abutment site. This fact, as well as the higher peak accelerations on the embankment, provides evidence of a strong influence of the structure of the dam on the ground motion at the embankment site.

Characterization of Earthquake-Induced Ground Motion from the L'Aquila Seismic Sequence of 2009, Italy

NASA Astrophysics Data System (ADS)

Malagnini, L.; Akinci, A.; Mayeda, K. M.; Munafo', I.; Herrmann, R. B.; Mercuri, A.

2010-12-01

Based only on weak-motion data, we carried out a combined study on region-specific source scaling and crustal attenuation in the Central Apennines (Italy). Our goal was to obtain a reappraisal of the existing predictive relationships for the ground motion, and to test them against the strong-motion data (Peak Ground Acceleration, PGA, Peak Ground Velocity, PGV, and Spectral Acceleration, SA) gathered during the Mw 6.15 L’Aquila earthquake (April 6, 2009, 01:32 UTC). The L’Aquila main-shock was not part of the predictive study, and the validation test was an extrapolation to one magnitude unit above the largest earthquake of the calibration data set. The regional attenuation was determined through a set of regressions on a data set of 12,777 high-quality, high-gain waveforms with excellent S/N ratios (4,259 vertical, and 8,518 horizontal time histories). Seismograms were selected from the recordings of 170 fore-shocks and after-shocks of the sequence (the complete set of all earthquakes with ML ≥ 3.0, from October 1, 2008, to May 10, 2010). All waveforms were downloaded from the ISIDe web page (http://iside.rm.ingv.it/iside/standard/index.jsp), a web site maintained by the Istituto Nazionale di Geofisica e Vulcanologia (INGV). Weak-motion data were used to obtain a moment tensor solution, as well as a coda-based moment-rate source spectrum, for each one of the 170 events of the L’Aquila sequence (2.8 ≤ Mw ≤ 6.15). Source spectra were used to verify the good agreement with the source scaling of the Colfiorito seismic sequence of 1997-98 recently described by Malagnini et al. (2008). Finally, results on source excitation and crustal attenuation were used to produce the absolute site terms for the 23 stations located within ~ 80 km of the epicentral area. The complete set of spectral corrections (crustal attenuation and absolute site effects) was used to implement a fast and accurate tool for the automatic computation of moment magnitudes in the Central

Characterization of earthquake-induced ground motion from the L'Aquila seismic sequence of 2009, Italy

NASA Astrophysics Data System (ADS)

Malagnini, Luca; Akinci, Aybige; Mayeda, Kevin; Munafo', Irene; Herrmann, Robert B.; Mercuri, Alessia

2011-01-01

Based only on weak-motion data, we carried out a combined study on region-specific source scaling and crustal attenuation in the Central Apennines (Italy). Our goal was to obtain a reappraisal of the existing predictive relationships for the ground motion, and to test them against the strong-motion data [peak ground acceleration (PGA), peak ground velocity (PGV) and spectral acceleration (SA)] gathered during the Mw 6.15 L'Aquila earthquake (2009 April 6, 01:32 UTC). The L'Aquila main shock was not part of the predictive study, and the validation test was an extrapolation to one magnitude unit above the largest earthquake of the calibration data set. The regional attenuation was determined through a set of regressions on a data set of 12 777 high-quality, high-gain waveforms with excellent S/N ratios (4259 vertical and 8518 horizontal time histories). Seismograms were selected from the recordings of 170 foreshocks and aftershocks of the sequence (the complete set of all earthquakes with ML≥ 3.0, from 2008 October 1 to 2010 May 10). All waveforms were downloaded from the ISIDe web page (), a web site maintained by the Istituto Nazionale di Geofisica e Vulcanologia (INGV). Weak-motion data were used to obtain a moment tensor solution, as well as a coda-based moment-rate source spectrum, for each one of the 170 events of the L'Aquila sequence (2.8 ≤Mw≤ 6.15). Source spectra were used to verify the good agreement with the source scaling of the Colfiorito seismic sequence of 1997-1998 recently described by Malagnini (2008). Finally, results on source excitation and crustal attenuation were used to produce the absolute site terms for the 23 stations located within ˜80 km of the epicentral area. The complete set of spectral corrections (crustal attenuation and absolute site effects) was used to implement a fast and accurate tool for the automatic computation of moment magnitudes in the Central Apennines.

Construction of Source Model of Huge Subduction Earthquakes for Strong Ground Motion Prediction

NASA Astrophysics Data System (ADS)

Iwata, T.; Asano, K.; Kubo, H.

2013-12-01

It is a quite important issue for strong ground motion prediction to construct the source model of huge subduction earthquakes. Iwata and Asano (2012, AGU) summarized the scaling relationships of large slip area of heterogeneous slip model and total SMGA sizes on seismic moment for subduction earthquakes and found the systematic change between the ratio of SMGA to the large slip area and the seismic moment. They concluded this tendency would be caused by the difference of period range of source modeling analysis. In this paper, we try to construct the methodology of construction of the source model for strong ground motion prediction for huge subduction earthquakes. Following to the concept of the characterized source model for inland crustal earthquakes (Irikura and Miyake, 2001; 2011) and intra-slab earthquakes (Iwata and Asano, 2011), we introduce the proto-type of the source model for huge subduction earthquakes and validate the source model by strong ground motion modeling.

Hazard assessment of long-period ground motions for the Nankai Trough earthquakes

NASA Astrophysics Data System (ADS)

Maeda, T.; Morikawa, N.; Aoi, S.; Fujiwara, H.

2013-12-01

We evaluate a seismic hazard for long-period ground motions associated with the Nankai Trough earthquakes (M8~9) in southwest Japan. Large interplate earthquakes occurring around the Nankai Trough have caused serious damages due to strong ground motions and tsunami; most recent events were in 1944 and 1946. Such large interplate earthquake potentially causes damages to high-rise and large-scale structures due to long-period ground motions (e.g., 1985 Michoacan earthquake in Mexico, 2003 Tokachi-oki earthquake in Japan). The long-period ground motions are amplified particularly on basins. Because major cities along the Nankai Trough have developed on alluvial plains, it is therefore important to evaluate long-period ground motions as well as strong motions and tsunami for the anticipated Nankai Trough earthquakes. The long-period ground motions are evaluated by the finite difference method (FDM) using 'characterized source models' and the 3-D underground structure model. The 'characterized source model' refers to a source model including the source parameters necessary for reproducing the strong ground motions. The parameters are determined based on a 'recipe' for predicting strong ground motion (Earthquake Research Committee (ERC), 2009). We construct various source models (~100 scenarios) giving the various case of source parameters such as source region, asperity configuration, and hypocenter location. Each source region is determined by 'the long-term evaluation of earthquakes in the Nankai Trough' published by ERC. The asperity configuration and hypocenter location control the rupture directivity effects. These parameters are important because our preliminary simulations are strongly affected by the rupture directivity. We apply the system called GMS (Ground Motion Simulator) for simulating the seismic wave propagation based on 3-D FDM scheme using discontinuous grids (Aoi and Fujiwara, 1999) to our study. The grid spacing for the shallow region is 200 m and

Analysis of the ground motions from the MW 7.8 Gorkha and MW 7.3 Dolakha earthquakes in Nepal in 2015

NASA Astrophysics Data System (ADS)

Martin, S. S.; Hough, S. E.; Gahalaut, V. K.; Joshi, A.; Landes, M.; Bossu, R.

2016-12-01

While the 25 April 2015 MW7.8 Gorkha, Nepal, earthquake took a heavy toll in Nepal, damage and fatalities were lower than expected. There is thus an urgent need to understand ground motions from the mainshock and largest aftershock. We collected 3,831 accounts of macroseismic effects that include sufficient information to assign intensities. To assess intensities reliably, we apply EMS guidelines with an appreciation for issues associated with macroseismic effects of earthquakes in the Indian subcontinent. We as also analyze 21 available strong motion recordings. Available data are consistent with the peak ground acceleration (PGA) versus intensity relationship of Worden et al. (2012). We use this relationship to estimate peak ground acceleration (PGAEMS) from all intensities. For nearest-fault distances (RRUP<200km), PGAEMS is consistent with the Atkinson and Boore (2003) (AB03) subduction zone ground motion prediction equation (GMPE); at greater distances, instrumental PGA values are consistent with AB03, while PGAEMS is systematically higher. We use PGAEMS values within 200 km to investigate the variability of ground motions using the AB03 GMPE as a baseline. Across the near-field region, PGAEMS is higher by a factor of 2.0-2.5 towards the northern edge of the rupture compared to the near-field region nearer to the southern, up-dip edge of the rupture. Inferred de-amplification in the deepest part of the Kathmandu valley supports the conclusion that former lake-bed sediments experienced a pervasive non-linear response during the mainshock (Dixit et al., 2015). Ground motions were amplified in the southern Gangetic basin, but were relatively low in the northern basin. The overall distribution of ground motions and damage during the Gorkha earthquake thus reflects a combination of complex source, path, and site effects. We also analyze ground motions for the 12 May 2015 Dolakha aftershock, which we conclude was likely a high stress-drop event.

Long-Period Ground Motion due to Near-Shear Earthquake Ruptures

NASA Astrophysics Data System (ADS)

Koketsu, K.; Yokota, Y.; Hikima, K.

2010-12-01

Long-period ground motion has become an increasingly important consideration because of the recent rapid increase in the number of large-scale structures, such as high-rise buildings and large oil storage tanks. Large subduction-zone earthquakes and moderate to large crustal earthquakes can generate far-source long-period ground motions in distant sedimentary basins with the help of path effects. Near-fault long-period ground motions are generated, for the most part, by the source effects of forward rupture directivity (Koketsu and Miyake, 2008). This rupture directivity effect is the maximum in the direction of fault rupture when a rupture velocity is nearly equal to shear wave velocity around a source fault (Dunham and Archuleta, 2005). The near-shear rupture was found to occur during the 2008 Mw 7.9 Wenchuan earthquake at the eastern edge of the Tibetan plateau (Koketsu et al., 2010). The variance of waveform residuals in a joint inversion of teleseismic and strong motion data was the minimum when we adopted a rupture velocity of 2.8 km/s, which is close to the shear wave velocity of 2.6 km/s around the hypocenter. We also found near-shear rupture during the 2010 Mw 6.9 Yushu earthquake (Yokota et al., 2010). The optimum rupture velocity for an inversion of teleseismic data is 3.5 km/s, which is almost equal to the shear wave velocity around the hypocenter. Since, in addition, supershear rupture was found during the 2001 Mw 7.8 Central Kunlun earthquake (Bouchon and Vallee, 2003), such fast earthquake rupture can be a characteristic of the eastern Tibetan plateau. Huge damage in Yingxiu and Beichuan from the 2008 Wenchuan earthquake and damage heavier than expected in the county seat of Yushu from the medium-sized Yushu earthquake can be attributed to the maximum rupture directivity effect in the rupture direction due to near-shear earthquake ruptures.

Analog-to-digital conversion as a source of drifts in displacements derived from digital recordings of ground acceleration

USGS Publications Warehouse

Boore, D.M.

2003-01-01

Displacements obtained from double integration of digitally recorded ground accelerations often show drifts much larger than those expected for the true ground displacements. These drifts might be due to many things, including dynamic elastic ground tilt, inelastic ground deformation, hysteresis in the instruments, and cross feed due to misalignment of nominally orthogonal sensors. This article shows that even if those effects were not present, the analog-to-digital conversion (ADC) process can produce apparent "pulses" and offsets in the acceleration baseline if the ground motion is slowly varying compared with the quantization level of the digitization. Such slowly varying signals can be produced by constant offsets that do not coincide with a quantization level and by near- and intermediate-field terms in the wave field radiated from earthquakes. Double integration of these apparent pulses and offsets leads to drifts in the displacements similar to those found in processing real recordings. These effects decrease in importance as the resolution of the ADC process increases.

The 2011 Mineral, VA M5.8 Earthquake Ground Motions and Stress Drop: An Important Contribution to the NGA East Ground Motion Database

NASA Astrophysics Data System (ADS)

Cramer, C. H.; Kutliroff, J.; Dangkua, D.

2011-12-01

The M5.8 Mineral, Virginia earthquake of August 23, 2011 is the largest instrumentally recorded earthquake in eastern North America since the 1988 M5.9 Saguenay, Canada earthquake. Historically, a similar magnitude earthquake occurred on May 31, 1897 at 18:58 UCT in western Virginia west of Roanoke. Paleoseismic evidence for larger magnitude earthquakes has also been found in the central Virginia region. The Next Generation Attenuation (NGA) East project to develop new ground motion prediction equations for stable continental regions (SCRs), including eastern North America (ENA), is ongoing at the Pacific Earthquake Engineering Research Center funded by the U.S. Nuclear Regulatory Commission, the U.S. Geological Survey, the Electric Power Research Institute, and the U.S. Department of Energy. The available recordings from the M5.8 Virginia are being added to the NGA East ground motion database. Close in (less than 100 km) strong motion recordings are particularly interesting for both ground motion and stress drop estimates as most close-in broadband seismometers clipped on the mainshock. A preliminary estimate for earthquake corner frequency for the M5.8 Virginia earthquake of ~0.7 Hz has been obtained from a strong motion record 57 km from the mainshock epicenter. For a M5.8 earthquake this suggests a Brune stress drop of ~300 bars for the Virginia event. Very preliminary comparisons using accelerometer data suggest the ground motions from the M5.8 Virginia earthquake agree well with current ENA ground motion prediction equations (GMPEs) at short periods (PGA, 0.2 s) and are below the GMPEs at longer periods (1.0 s), which is the same relationship seen from other recent M5 ENA earthquakes. We will present observed versus GMPE ground motion comparisons for all the ground motion observations and stress drop estimates from strong motion recordings at distances less than 100 km. A review of the completed NGA East ENA ground motion database will also be provided.

Modelling of Earthquake Ground Response in the Maltese Islands Using Results from Geophysical Investigations

NASA Astrophysics Data System (ADS)

Farrugia, D.; Galea, P. M.; D'Amico, S.

2016-12-01

The Maltese archipelago is characterised by a four layer sequence of limestones and clays. The Lower Coralline Limestone is the oldest exposed layer, overlain by the Globigerina Limestone. Some parts of the islands are characterised by Upper Coralline Limestone plateaus and hillcaps covering a soft Blue Clay layer which can be up to 75 m thick. The BC layer introduces a velocity inversion in the stratigraphy, and makes the Vs30 parameter not always suitable for seismic microzonation purposes. Such a layer may still produce amplification effects, however would not contribute to the numerical mean of Vs in the upper 30m. In this study, site response analysis for the Maltese islands is conducted, with particular attention being given to sites described above. Array and single-station measurements of ambient noise were first carried out at numerous sites in Malta. Surface wave dispersion and H/V curves were jointly inverted using a genetic algorithm, so that the Vs profiles were obtained. The stochastic extended-fault algorithm EXSIM was used to simulate historical and recent earthquakes at the bedrock. These were used in conjunction with the equivalent-linear programme SHAKE2000 to carry out the site-specific response analysis, using the derived geophysical models. Maps of ground motion parameters, such as peak ground acceleration and spectral accelerations, confirm that the clay, even when buried under a hard outcropping layer can still produce significant amplifications at frequencies which are of engineering interest when considering the recent urbanisation patterns. The results of this project will give important, and previously unavailable information and predictions about the behaviour of local lithotypes in response to earthquake ground shaking while also contributing knowledge about the issue of buried low velocity layers.

Rapid acceleration leads to rapid weakening in earthquake-like laboratory experiments

NASA Astrophysics Data System (ADS)

Chang, J. C.; Lockner, D. A.; Reches, Z.

2012-12-01

We simulated the slip of a fault-patch during a large earthquake by rapidly loading an experimental, ring-shaped fault with energy stored in a spinning flywheel. The flywheel abruptly delivers a finite amount of energy by spinning the fault-patch that spontaneously dissipates the energy without operator intervention. We conducted 42 experiments on Sierra White granite (SWG) samples, and 24 experiments on Kasota dolomite (KD) samples. Each experiment starts by spinning a 225 kg disk-shaped flywheel to a prescribed angular velocity. We refer to this experiment as an "earthquake-like slip-event" (ELSE). The strength-evolution in ELSE experiments is similar to the strength-evolution proposed for earthquake models and observed in stick-slip experiments. Further, we found that ELSE experiments are similar to earthquakes in at least three ways: (1) slip driven by the release of a finite amount of stored energy; (2) pattern of fault strength evolution; and (3) seismically observed values, such as average slip, peak-velocity and rise-time. By assuming that the measured slip, D, in ELSE experiments is equivalent to the average slip during an earthquake, we found that ELSE experiments (D = 0.003-4.6 m) correspond to earthquakes in moment-magnitude range of Mw = 4-8. In ELSE experiments, the critical-slip-distance, dc, has mean values of 2.7 cm and 1.2 cm for SWG and KD, that are much shorter than the 1-10 m in steady-state classical experiments in rotary shear systems. We attribute these dc values, to ELSE loading in which the fault-patch is abruptly loaded by impact with a spinning flywheel. Under this loading, the friction-velocity relations are strikingly different from those under steady-state loading on the same rock samples with the same shear system (Reches and Lockner, Nature, 2010). We further note that the slip acceleration in ELSE evolves systematically with fault strength and wear-rate, and that the dynamic weakening is restricted to the period of intense

The Loma Prieta, California, Earthquake of October 17, 1989: Strong Ground Motion and Ground Failure

USGS Publications Warehouse

Coordinated by Holzer, Thomas L.

1992-01-01

Professional Paper 1551 describes the effects at the land surface caused by the Loma Prieta earthquake. These effects: include the pattern and characteristics of strong ground shaking, liquefaction of both floodplain deposits along the Pajaro and Salinas Rivers in the Monterey Bay region and sandy artificial fills along the margins of San Francisco Bay, landslides in the epicentral region, and increased stream flow. Some significant findings and their impacts were: * Strong shaking that was amplified by a factor of about two by soft soils caused damage at up to 100 kilometers (60 miles) from the epicenter. * Instrumental recordings of the ground shaking have been used to improve how building codes consider site amplification effects from soft soils. * Liquefaction at 134 locations caused $99.2 million of the total earthquake loss of $5.9 billion. Liquefaction of floodplain deposits and sandy artificial fills was similar in nature to that which occurred in the 1906 San Francisco earthquake and indicated that many areas remain susceptible to liquefaction damage in the San Francisco and Monterey Bay regions. * Landslides caused $30 million in earthquake losses, damaging at least 200 residences. Many landslides showed evidence of movement in previous earthquakes. * Recognition of the similarities between liquefaction and landslides in 1906 and 1989 and research in intervening years that established methodologies to map liquefaction and landslide hazards prompted the California legislature to pass in 1990 the Seismic Hazards Mapping Act that required the California Geological Survey to delineate regulatory zones of areas potentially susceptible to these hazards. * The earthquake caused the flow of many streams in the epicentral region to increase. Effects were noted up to 88 km from the epicenter. * Post-earthquake studies of the Marina District of San Francisco provide perhaps the most comprehensive case history of earthquake effects at a specific site developed for

Characteristics of strong ground motion generation areas by fully dynamic earthquake cycles

NASA Astrophysics Data System (ADS)

Galvez, P.; Somerville, P.; Ampuero, J. P.; Petukhin, A.; Yindi, L.

2016-12-01

During recent subduction zone earthquakes (2010 Mw 8.8 Maule and 2011 Mw 9.0 Tohoku), high frequency ground motion radiation has been detected in deep regions of seismogenic zones. By semblance analysis of wave packets, Kurahashi & Irikura (2013) found strong ground motion generation areas (SMGAs) located in the down dip region of the 2011 Tohoku rupture. To reproduce the rupture sequence of SMGA's and replicate their rupture time and ground motions, we extended previous work on dynamic rupture simulations with slip reactivation (Galvez et al, 2016). We adjusted stresses on the most southern SMGAs of Kurahashi & Irikura (2013) model to reproduce the observed peak ground velocity recorded at seismic stations along Japan for periods up to 5 seconds. To generate higher frequency ground motions we input the rupture time, final slip and slip velocity of the dynamic model into the stochastic ground motion generator of Graves & Pitarka (2010). Our results are in agreement with the ground motions recorded at the KiK-net and K-NET stations.While we reproduced the recorded ground motions of the 2011 Tohoku event, it is unknown whether the characteristics and location of SMGA's will persist in future large earthquakes in this region. Although the SMGA's have large peak slip velocities, the areas of largest final slip are located elsewhere. To elucidate whether this anti-correlation persists in time, we conducted earthquake cycle simulations and analysed the spatial correlation of peak slip velocities, stress drops and final slip of main events. We also investigated whether or not the SMGA's migrate to other regions of the seismic zone.To perform this study, we coupled the quasi-dynamic boundary element solver QDYN (Luo & Ampuero, 2015) and the dynamic spectral element solver SPECFEM3D (Galvez et al., 2014; 2016). The workflow alternates between inter-seismic periods solved with QDYN and coseismic periods solved with SPECFEM3D, with automated switch based on slip rate

Simulated ground motion in Santa Clara Valley, California, and vicinity from M≥6.7 scenario earthquakes

USGS Publications Warehouse

Harmsen, Stephen C.; Hartzell, Stephen

2008-01-01

Models of the Santa Clara Valley (SCV) 3D velocity structure and 3D finite-difference software are used to predict ground motions from scenario earthquakes on the San Andreas (SAF), Monte Vista/Shannon, South Hayward, and Calaveras faults. Twenty different scenario ruptures are considered that explore different source models with alternative hypocenters, fault dimensions, and rupture velocities and three different velocity models. Ground motion from the full wave field up to 1 Hz is exhibited as maps of peak horizontal velocity and pseudospectral acceleration at periods of 1, 3, and 5 sec. Basin edge effects and amplification in sedimentary basins of the SCV are observed that exhibit effects from shallow sediments with relatively low shear-wave velocity (330 m/sec). Scenario earthquakes have been simulated for events with the following magnitudes: (1) M 6.8–7.4 Calaveras sources, (2) M 6.7–6.9 South Hayward sources, (3) M 6.7 Monte Vista/Shannon sources, and (4) M 7.1–7.2 Peninsula segment of the SAF sources. Ground motions are strongly influenced by source parameters such as rupture velocity, rise time, maximum depth of rupture, hypocenter, and source directivity. Cenozoic basins also exert a strong influence on ground motion. For example, the Evergreen Basin on the northeastern side of the SCV is especially responsive to 3–5-sec energy from most scenario earthquakes. The Cupertino Basin on the southwestern edge of the SCV tends to be highly excited by many Peninsula and Monte Vista fault scenarios. Sites over the interior of the Evergreen Basin can have long-duration coda that reflect the trapping of seismic energy within this basin. Plausible scenarios produce predominantly 5-sec wave trains with greater than 30 cm/sec sustained ground-motion amplitude with greater than 30 sec duration within the Evergreen Basin.

Seismology and Earthquake Ground Motions of the August 24, 2014 M6 South Napa Earthquake

NASA Astrophysics Data System (ADS)

Kishida, T.; Wang, S.; Mazzoni, S.; Markam, C.; Lu, Y.; Bozorgnia, Y.; Mahin, S.; Bray, J.; Panagiotou, M.; Stewart, J. P.; Darragh, R. B.; Abrahamson, N. A.; Hollenback, J. C.; Gutierrez, C.; Chiou, B.; Muin, S.; Dreger, D. S.

2014-12-01

The M6.0 South Napa earthquake produced strong ground motions in the northern San Francisco Bay area. A total of 214 three-component uncorrected digital accelerograms were downloaded from the CESMD website and processed following the PEER standard procedure (Ancheta et al. 2014). Intense ground motions were recorded in the heavily damaged area of Napa with peak acceleration greater than 0.3 g. Pulse-like waveforms were observed in several of the velocity time series at the near-fault stations. Near-fault velocity time series were rotated into fault normal and fault parallel directions and then characterized as pulse-like or non pulse-like according to previous studies by Hayden et al. (2014), Shahi (2013), and Lu and Panagiotou (2014). The near-fault velocity time series at five stations contained pulses with periods within the expected range of 0.7 s to 2.0 s for soil sites (Bray et al. 2009). However, they also contained longer period pulses than the expected range. High-frequency spikes were recorded at Carquinez Bridge Geotechnical Array #1 (CBGA1) of approximately 1.0 g on the NS component. These spikes were in the S-wave portion and were consistently observed in the downhole arrays and several other sites along the same azimuth from the source. The spikes increase in amplitude both from the Hwy 37/Napa River East Geotechnical Array to CBGA1 and from a depth below 100 m to the surface. This suggests that the spikes could be a result of path effects and site amplification through the surficial soft soil deposits. However, these observations do not exclude the possibility of soil-structure interaction effects on the measured recordings. The 5% damped pseudo-spectral accelerations (PSA) from the recorded ground motions compared well to those estimated from the recent NGA-West2 GMPEs. The exceptions are that PSA is under predicted from 1 to 3 seconds at several near fault records due to the velocity pulses and for short periods at Carquinez Bridge where the large

Source Rupture Process for the February 21, 2011, Mw6.1, New Zealand Earthquake and the Characteristics of Near-field Strong Ground Motion

NASA Astrophysics Data System (ADS)

Meng, L.; Shi, B.

2011-12-01

The New Zealand Earthquake of February 21, 2011, Mw 6.1 occurred in the South Island, New Zealand with the epicenter at longitude 172.70°E and latitude 43.58°S, and with depth of 5 km. The Mw 6.1 earthquake occurred on an unknown blind fault involving oblique-thrust faulting, which is 9 km away from southern of the Christchurch, the third largest city of New Zealand, with a striking direction from east toward west (United State Geology Survey, USGS, 2011). The earthquake killed at least 163 people and caused a lot of construction damages in Christchurch city. The Peak Ground Acceleration (PGA) observed at station Heathcote Valley Primary School (HVSC), which is 1 km away from the epicenter, is up to almost 2.0g. The ground-motion observation suggests that the buried earthquake source generates much higher near-fault ground motion. In this study, we have analyzed the earthquake source spectral parameters based on the strong motion observations, and estimated the near-fault ground motion based on the Brune's circular fault model. The results indicate that the larger ground motion may be caused by a higher dynamic stress drop,Δσd , or effect stress drop named by Brune, in the major source rupture region. In addition, a dynamical composite source model (DCSM) has been developed to simulate the near-fault strong ground motion with associated fault rupture properties from the kinematic point of view. For comparison purpose, we also conducted the broadband ground motion predictions for the station of HVSC; the synthetic seismogram of time histories produced for this station has good agreement with the observations in the waveforms, peak values and frequency contents, which clearly indicate that the higher dynamic stress drop during the fault rupture may play an important role to the anomalous ground-motion amplification. The preliminary simulated result illustrated in at Station HVSC is that the synthetics seismograms have a realistic appearance in the waveform and

Earthquake Ground Motion Simulations in the Central United States

NASA Astrophysics Data System (ADS)

Ramirez Guzman, L.; Boyd, O. S.; Hartzell, S.; Williams, R. A.

2010-12-01

The Central United States (CUS) includes two of the major seismic zones east of the Rockies: the New Madrid and Wabash Valley Seismic Zones. The winter 1811-1812 New Madrid Seismic Zone (NMSZ) events were the largest intraplate sequence ever recorded in the United States. Together with their aftershocks, these earthquakes produced large areas of liquefaction, new lakes, and landslides in the region. Seismicity in the early 1800’s was dominated by the NMSZ activity, although three low magnitude 5 earthquakes occurred in the last 40 years in the Wabash Valley Seismic Zone (WVSZ). The population and infrastructure of the CUS have drastically changed from that of the early nineteenth century, and a large earthquake would now cause significant casualties and economic losses within the country’s heartland. In this study we present three sets of numerical simulations depicting earthquakes in the region. These hypothetical ruptures are located on the Reelfoot fault and the southern axial arm of the NMSZ and in the WVSZ. Our broad-band synthetic ground motions are calculated following the Liu et al. (2006) hybrid method. Using a finite element solver we calculate low frequency ground motion (< 1 Hz) which accounts for the heterogeneity and low velocity soils of the region by using a recently developed seismic velocity model (CUSVM1) and a minimum shear wave velocity of 300 m/s. The broad-band ground motions are then generated by combining high frequency synthetics computed in a 1D velocity model with the low frequency motions at a crossover frequency of 1 Hz. We primarily discuss the basin effects produced by the Mississippi embayment and investigate the effects of hypocentral location and slip distribution on ground motions in densely populated areas within the CUS.

Stochastic ground motion simulation

USGS Publications Warehouse

Rezaeian, Sanaz; Xiaodan, Sun; Beer, Michael; Kougioumtzoglou, Ioannis A.; Patelli, Edoardo; Siu-Kui Au, Ivan

2014-01-01

Strong earthquake ground motion records are fundamental in engineering applications. Ground motion time series are used in response-history dynamic analysis of structural or geotechnical systems. In such analysis, the validity of predicted responses depends on the validity of the input excitations. Ground motion records are also used to develop ground motion prediction equations(GMPEs) for intensity measures such as spectral accelerations that are used in response-spectrum dynamic analysis. Despite the thousands of available strong ground motion records, there remains a shortage of records for large-magnitude earthquakes at short distances or in specific regions, as well as records that sample specific combinations of source, path, and site characteristics.

Seismic Disaster Mitigation in Urban Area by using Building Vibration Observation of Weak Earthquake Ground Motion: an Approach of the IT Kyoshin Seismometer for Buildings

NASA Astrophysics Data System (ADS)

Takano, K.; Ito, T.

2010-12-01

There are a lot of buildings which is not experienced severe earthquakes in urban area. In Hanshin-Awaji (Kobe) Earthquake, it was presumed that 80 percent or more of the person was dead immediately after the earthquake by building collapse. Also in Haiti, a lot of buildings deprived of the life of persons. In order to prevent the earthquake damage of urban area, it is the most effective to make the building earthquake-proof. However, there are still a lot of buildings not made earthquake-proof in Japan though 15 years passed since Kobe Earthquake. In order to promote making of the building earthquake-proof, various approaches such as visualization of seismic hazard, education of disaster prevention and legal system for promotion are needed. We have developed the IT Kyoshin(strong motion) Seismometer for Building which is the observation system of the usual weak earthquake ground motion by installing a lot of acceleration sensors in building, and have been setting it up in some buildings of the University of Tokyo. We have also developed the visualization tool that can reproduce the building vibration during earthquake from the observed data. By this tool, we can successfully show where is more shaking in the building or what is the feature of building vibration easily. Such information contributes to not only promotion of making building earthquake-proof but also promotion of disaster prevention action such as fixation of bookshelf, making the safety area in building, etc. In addition, we proposed a concrete technique of the health investigation of buildings by using weak earthquake ground motion. Because there are 20 to 30 felt earthquakes in year in Tokyo area, it is possible to observe these building vibrations by using weak earthquake ground motions. In addition, we have developed the high sensitive ITK sensor which can observe from the microtremor to the felt earthquake in the place without the felt earthquake either.

Tunnel flexibility effect on the ground surface acceleration response

NASA Astrophysics Data System (ADS)

Baziar, Mohammad Hassan; Moghadam, Masoud Rabeti; Choo, Yun Wook; Kim, Dong-Soo

2016-09-01

Flexibility of underground structures relative to the surrounding medium, referred to as the flexibility ratio, is an important factor that influences their dynamic interaction. This study investigates the flexibility effect of a box-shaped subway tunnel, resting directly on bedrock, on the ground surface acceleration response using a numerical model verified against dynamic centrifuge test results. A comparison of the ground surface acceleration response for tunnel models with different flexibility ratios revealed that the tunnels with different flexibility ratios influence the acceleration response at the ground surface in different ways. Tunnels with lower flexibility ratios have higher acceleration responses at short periods, whereas tunnels with higher flexibility ratios have higher acceleration responses at longer periods. The effect of the flexibility ratio on ground surface acceleration is more prominent in the high range of frequencies. Furthermore, as the flexibility ratio of the tunnel system increases, the acceleration response moves away from the free field response and shifts towards the longer periods. Therefore, the flexibility ratio of the underground tunnels influences the peak ground acceleration (PGA) at the ground surface, and may need to be considered in the seismic zonation of urban areas.

Synthesis of High-Frequency Ground Motion Using Information Extracted from Low-Frequency Ground Motion

NASA Astrophysics Data System (ADS)

Iwaki, A.; Fujiwara, H.

2012-12-01

Broadband ground motion computations of scenario earthquakes are often based on hybrid methods that are the combinations of deterministic approach in lower frequency band and stochastic approach in higher frequency band. Typical computation methods for low-frequency and high-frequency (LF and HF, respectively) ground motions are the numerical simulations, such as finite-difference and finite-element methods based on three-dimensional velocity structure model, and the stochastic Green's function method, respectively. In such hybrid methods, LF and HF wave fields are generated through two different methods that are completely independent of each other, and are combined at the matching frequency. However, LF and HF wave fields are essentially not independent as long as they are from the same event. In this study, we focus on the relation among acceleration envelopes at different frequency bands, and attempt to synthesize HF ground motion using the information extracted from LF ground motion, aiming to propose a new method for broad-band strong motion prediction. Our study area is Kanto area, Japan. We use the K-NET and KiK-net surface acceleration data and compute RMS envelope at four frequency bands: 0.5-1.0 Hz, 1.0-2.0 Hz, 2.0-4.0 Hz, .0-8.0 Hz, and 8.0-16.0 Hz. Taking the ratio of the envelopes of adjacent bands, we find that the envelope ratios have stable shapes at each site. The empirical envelope-ratio characteristics are combined with low-frequency envelope of the target earthquake to synthesize HF ground motion. We have applied the method to M5-class earthquakes and a M7 target earthquake that occurred in the vicinity of Kanto area, and successfully reproduced the observed HF ground motion of the target earthquake. The method can be applied to a broad band ground motion simulation for a scenario earthquake by combining numerically-computed low-frequency (~1 Hz) ground motion with the empirical envelope ratio characteristics to generate broadband ground motion

Predicted Attenuation Relation and Observed Ground Motion of Gorkha Nepal Earthquake of 25 April 2015

NASA Astrophysics Data System (ADS)

Singh, R. P.; Ahmad, R.

2015-12-01

A comparison of recent observed ground motion parameters of recent Gorkha Nepal earthquake of 25 April 2015 (Mw 7.8) with the predicted ground motion parameters using exitsing attenuation relation of the Himalayan region will be presented. The recent earthquake took about 8000 lives and destroyed thousands of poor quality of buildings and the earthquake was felt by millions of people living in Nepal, China, India, Bangladesh, and Bhutan. The knowledge of ground parameters are very important in developing seismic code of seismic prone regions like Himalaya for better design of buildings. The ground parameters recorded in recent earthquake event and aftershocks are compared with attenuation relations for the Himalayan region, the predicted ground motion parameters show good correlation with the observed ground parameters. The results will be of great use to Civil engineers in updating existing building codes in the Himlayan and surrounding regions and also for the evaluation of seismic hazards. The results clearly show that the attenuation relation developed for the Himalayan region should be only used, other attenuation relations based on other regions fail to provide good estimate of observed ground motion parameters.

Empirical models for the prediction of ground motion duration for intraplate earthquakes

NASA Astrophysics Data System (ADS)

Anbazhagan, P.; Neaz Sheikh, M.; Bajaj, Ketan; Mariya Dayana, P. J.; Madhura, H.; Reddy, G. R.

2017-07-01

Many empirical relationships for the earthquake ground motion duration were developed for interplate region, whereas only a very limited number of empirical relationships exist for intraplate region. Also, the existing relationships were developed based mostly on the scaled recorded interplate earthquakes to represent intraplate earthquakes. To the author's knowledge, none of the existing relationships for the intraplate regions were developed using only the data from intraplate regions. Therefore, an attempt is made in this study to develop empirical predictive relationships of earthquake ground motion duration (i.e., significant and bracketed) with earthquake magnitude, hypocentral distance, and site conditions (i.e., rock and soil sites) using the data compiled from intraplate regions of Canada, Australia, Peninsular India, and the central and southern parts of the USA. The compiled earthquake ground motion data consists of 600 records with moment magnitudes ranging from 3.0 to 6.5 and hypocentral distances ranging from 4 to 1000 km. The non-linear mixed-effect (NLMEs) and logistic regression techniques (to account for zero duration) were used to fit predictive models to the duration data. The bracketed duration was found to be decreased with an increase in the hypocentral distance and increased with an increase in the magnitude of the earthquake. The significant duration was found to be increased with the increase in the magnitude and hypocentral distance of the earthquake. Both significant and bracketed durations were predicted higher in rock sites than in soil sites. The predictive relationships developed herein are compared with the existing relationships for interplate and intraplate regions. The developed relationship for bracketed duration predicts lower durations for rock and soil sites. However, the developed relationship for a significant duration predicts lower durations up to a certain distance and thereafter predicts higher durations compared to the

Near Fault Strong Ground Motion Records in the Kathmandu Valley during the 2015 Gorkha Nepal Earthquake

NASA Astrophysics Data System (ADS)

Takai, N.; Shigefuji, M.; Rajaure, S.; Bijukchhen, S.; Ichiyanagi, M.; Dhital, M. R.; Sasatani, T.

2015-12-01

Kathmandu is the capital of Nepal and is located in the Kathmandu Valley, which is formed by soft lake sediments of Plio-Pleistocene origin. Large earthquakes in the past have caused significant damage as the seismic waves were amplified in the soft sediments. To understand the site effect of the valley structure, we installed continuous recording accelerometers in four different parts of the valley. Four stations were installed along a west-to-east profile of the valley at KTP (Kirtipur; hill top), TVU (Kirtipur; hill side), PTN (Patan) and THM (Thimi). On 25 April 2015, a large interplate earthquake Mw 7.8 occurred in the Himalayan Range of Nepal. The focal area estimated was about 200 km long and 150 km wide, with a large slip area under the Kathmandu Valley where our strong motion observation stations were installed. The strong ground motions were observed during this large damaging earthquake. The maximum horizontal peak ground acceleration at the rock site was 271 cm s-2, and the maximum horizontal peak ground velocity at the sediment sites reached 112 cm s-1. We compared these values with the empirical attenuation formula for strong ground motions. We found the peak accelerations were smaller and the peak velocities were approximately the same as the predicted values. The rock site KTP motions are less affected by site amplification and were analysed further. The horizontal components were rotated to the fault normal (N205E) and fault parallel (N115E) directions using the USGS fault model. The velocity waveforms at KTP showed about 5 s triangular pulses on the N205E and the up-down components; however the N115E component was not a triangular pulse but one cycle sinusoidal wave. The velocity waveforms at KTP were integrated to derive the displacement waveforms. The derived displacements at KTP are characterized by a monotonic step on the N205E normal and up-down components. The displacement waveforms of KTP show permanent displacements of 130 cm in the fault

Simulation of broad-band strong ground motion for a hypothetical Mw 7.1 earthquake on the Enriquillo Fault in Haiti

NASA Astrophysics Data System (ADS)

Douilly, Roby; Mavroeidis, George P.; Calais, Eric

2017-10-01

The devastating 2010 Mw 7.0 Haiti earthquake demonstrated the need to improve mitigation and preparedness for future seismic events in the region. Previous studies have shown that the earthquake did not occur on the Enriquillo Fault, the main plate boundary fault running through the heavily populated Port-au-Prince region, but on the nearby and previously unknown transpressional Léogâne Fault. Slip on that fault has increased stresses on the segment of Enriquillo Fault to the east of Léogâne, which terminates in the ˜3-million-inhabitant capital city of Port-au-Prince. In this study, we investigate ground shaking in the vicinity of Port-au-Prince, if a hypothetical rupture similar to the 2010 Haiti earthquake occurred on that segment of the Enriquillo Fault. We use a finite element method and assumptions on regional tectonic stress to simulate the low-frequency ground motion components using dynamic rupture propagation for a 52-km-long segment. We consider eight scenarios by varying parameters such as hypocentre location, initial shear stress and fault dip. The high-frequency ground motion components are simulated using the specific barrier model in the context of the stochastic modeling approach. The broad-band ground motion synthetics are subsequently obtained by combining the low-frequency components from the dynamic rupture simulation with the high-frequency components from the stochastic simulation using matched filtering at a crossover frequency of 1 Hz. Results show that rupture on a vertical Enriquillo Fault generates larger horizontal permanent displacements in Léogâne and Port-au-Prince than rupture on a south-dipping Enriquillo Fault. The mean horizontal peak ground acceleration (PGA), computed at several sites of interest throughout Port-au-Prince, has a value of ˜0.45 g, whereas the maximum horizontal PGA in Port-au-Prince is ˜0.60 g. Even though we only consider a limited number of rupture scenarios, our results suggest more intense ground

"Did you feel it?" Intensity data: A surprisingly good measure of earthquake ground motion

USGS Publications Warehouse

Atkinson, G.M.; Wald, D.J.

2007-01-01

The U.S. Geological Survey is tapping a vast new source of engineering seismology data through its "Did You Feel It?" (DYFI) program, which collects online citizen responses to earthquakes. To date, more than 750,000 responses have been compiled in the United States alone. The DYFI data make up in quantity what they may lack in scientific quality and offer the potential to resolve longstanding issues in earthquake ground-motion science. Such issues have been difficult to address due to the paucity of instrumental ground-motion data in regions of low seismicity. In particular, DYFI data provide strong evidence that earthquake stress drops, which control the strength of high-frequency ground shaking, are higher in the central and eastern United States (CEUS) than in California. Higher earthquake stress drops, coupled with lower attenuation of shaking with distance, result in stronger overall shaking over a wider area and thus more potential damage for CEUS earthquakes in comparison to those of equal magnitude in California - a fact also definitively captured with these new DYFI data and maps.

A Hybrid Ground-Motion Prediction Equation for Earthquakes in Western Alberta

NASA Astrophysics Data System (ADS)

Spriggs, N.; Yenier, E.; Law, A.; Moores, A. O.

2015-12-01

Estimation of ground-motion amplitudes that may be produced by future earthquakes constitutes the foundation of seismic hazard assessment and earthquake-resistant structural design. This is typically done by using a prediction equation that quantifies amplitudes as a function of key seismological variables such as magnitude, distance and site condition. In this study, we develop a hybrid empirical prediction equation for earthquakes in western Alberta, where evaluation of seismic hazard associated with induced seismicity is of particular interest. We use peak ground motions and response spectra from recorded seismic events to model the regional source and attenuation attributes. The available empirical data is limited in the magnitude range of engineering interest (M>4). Therefore, we combine empirical data with a simulation-based model in order to obtain seismologically informed predictions for moderate-to-large magnitude events. The methodology is two-fold. First, we investigate the shape of geometrical spreading in Alberta. We supplement the seismic data with ground motions obtained from mining/quarry blasts, in order to gain insights into the regional attenuation over a wide distance range. A comparison of ground-motion amplitudes for earthquakes and mining/quarry blasts show that both event types decay at similar rates with distance and demonstrate a significant Moho-bounce effect. In the second stage, we calibrate the source and attenuation parameters of a simulation-based prediction equation to match the available amplitude data from seismic events. We model the geometrical spreading using a trilinear function with attenuation rates obtained from the first stage, and calculate coefficients of anelastic attenuation and site amplification via regression analysis. This provides a hybrid ground-motion prediction equation that is calibrated for observed motions in western Alberta and is applicable to moderate-to-large magnitude events.

What can we learn from the Wells, NV earthquake sequence about seismic hazard in the intermountain west?

USGS Publications Warehouse

Petersen, M.D.; Pankow, K.L.; Biasi, G.P.; Meremonte, M.

2008-01-01

The February 21, 2008 Wells, NV earthquake (M 6) was felt throughout eastern Nevada, southern Idaho, and western Utah. The town of Wells sustained significant damage to unreinforced masonry buildings. The earthquake occurred in a region of low seismic hazard with little seismicity, low geodetic strain rates, and few mapped faults. The peak horizontal ground acceleration predicted by the USGS National Seismic Hazard Maps is about 0.2 g at 2% probability of exceedance in 50 years, with the contributions coming mostly from the Ruby Mountain fault and background seismicity (M5-7.0). The hazard model predicts that the probability of occurrence of an M>6 event within 50 km of Wells is about 15% in 100 years. Although the earthquake was inside the USArray Transportable Array network, the nearest on-scale recordings of ground motions from the mainshock were too distant to estimate accelerations in town. The University of Nevada Reno, the University of Utah, and the U.S. Geological Survey deployed portable instruments to capture the ground motions from aftershocks of this rare normal-faulting event. Shaking from a M 4.7 aftershock recorded on portable instruments at distances less than 10 km exceeded 0.3 g, and sustained accelerations above 0.1 g lasted for about 5 seconds. For a magnitude 5 earthquake at 10 km distance the NGA equations predict median peak ground accelerations about 0.1 g. Ground motions from normal faulting earthquakes are poorly represented in the ground motion prediction equations. We compare portable and Transportable Array ground-motion recordings with prediction equations. Advanced National Seismic System stations in Utah recorded ground motions 250 km from the mainshock of about 2% g. The maximum ground motion recorded in Salt Lake City was in the center of the basin. We analyze the spatial variability of ground motions (rock vs. soil) and the influence of the Salt Lake Basin in modifying the ground motions. We then compare this data with the

Visualizing the ground motions of the 1906 San Francisco earthquake

USGS Publications Warehouse

Chourasia, A.; Cutchin, S.; Aagaard, Brad T.

2008-01-01

With advances in computational capabilities and refinement of seismic wave-propagation models in the past decade large three-dimensional simulations of earthquake ground motion have become possible. The resulting datasets from these simulations are multivariate, temporal and multi-terabyte in size. Past visual representations of results from seismic studies have been largely confined to static two-dimensional maps. New visual representations provide scientists with alternate ways of viewing and interacting with these results potentially leading to new and significant insight into the physical phenomena. Visualizations can also be used for pedagogic and general dissemination purposes. We present a workflow for visual representation of the data from a ground motion simulation of the great 1906 San Francisco earthquake. We have employed state of the art animation tools for visualization of the ground motions with a high degree of accuracy and visual realism. ?? 2008 Elsevier Ltd.

Geodetic Finite-Fault-based Earthquake Early Warning Performance for Great Earthquakes Worldwide

NASA Astrophysics Data System (ADS)

Ruhl, C. J.; Melgar, D.; Grapenthin, R.; Allen, R. M.

2017-12-01

GNSS-based earthquake early warning (EEW) algorithms estimate fault-finiteness and unsaturated moment magnitude for the largest, most damaging earthquakes. Because large events are infrequent, algorithms are not regularly exercised and insufficiently tested on few available datasets. The Geodetic Alarm System (G-larmS) is a GNSS-based finite-fault algorithm developed as part of the ShakeAlert EEW system in the western US. Performance evaluations using synthetic earthquakes offshore Cascadia showed that G-larmS satisfactorily recovers magnitude and fault length, providing useful alerts 30-40 s after origin time and timely warnings of ground motion for onshore urban areas. An end-to-end test of the ShakeAlert system demonstrated the need for GNSS data to accurately estimate ground motions in real-time. We replay real data from several subduction-zone earthquakes worldwide to demonstrate the value of GNSS-based EEW for the largest, most damaging events. We compare predicted ground acceleration (PGA) from first-alert-solutions with those recorded in major urban areas. In addition, where applicable, we compare observed tsunami heights to those predicted from the G-larmS solutions. We show that finite-fault inversion based on GNSS-data is essential to achieving the goals of EEW.

A comparison of observed and predicted ground motions from the 2015 MW7.8 Gorkha, Nepal, earthquake

USGS Publications Warehouse

Hough, Susan E.; Martin, Stacey S.; Gahalaut, V.; Joshi, A.; Landes, M.; Bossu, R.

2016-01-01

We use 21 strong motion recordings from Nepal and India for the 25 April 2015 moment magnitude (MW) 7.8 Gorkha, Nepal, earthquake together with the extensive macroseismic intensity data set presented by Martin et al. (Seism Res Lett 87:957–962, 2015) to analyse the distribution of ground motions at near-field and regional distances. We show that the data are consistent with the instrumental peak ground acceleration (PGA) versus macroseismic intensity relationship developed by Worden et al. (Bull Seism Soc Am 102:204–221, 2012), and use this relationship to estimate peak ground acceleration from intensities (PGAEMS). For nearest-fault distances (RRUP < 200 km), PGAEMS is consistent with the Atkinson and Boore (Bull Seism Soc Am 93:1703–1729, 2003) subduction zone ground motion prediction equation (GMPE). At greater distances (RRUP > 200 km), instrumental PGA values are consistent with this GMPE, while PGAEMS is systematically higher. We suggest the latter reflects a duration effect whereby effects of weak shaking are enhanced by long-duration and/or long-period ground motions from a large event at regional distances. We use PGAEMS values within 200 km to investigate the variability of high-frequency ground motions using the Atkinson and Boore (Bull Seism Soc Am 93:1703–1729, 2003) GMPE as a baseline. Across the near-field region, PGAEMS is higher by a factor of 2.0–2.5 towards the northern, down-dip edge of the rupture compared to the near-field region nearer to the southern, up-dip edge of the rupture. Inferred deamplification in the deepest part of the Kathmandu valley supports the conclusion that former lake-bed sediments experienced a pervasive nonlinear response during the mainshock (Dixit et al. in Seismol Res Lett 86(6):1533–1539, 2015; Rajaure et al. in Tectonophysics, 2016. Ground motions were significantly amplified in the southern Gangetic basin, but were relatively low in the northern basin. The overall distribution of ground motions

Conditional spectrum computation incorporating multiple causal earthquakes and ground-motion prediction models

USGS Publications Warehouse

Lin, Ting; Harmsen, Stephen C.; Baker, Jack W.; Luco, Nicolas

2013-01-01

The conditional spectrum (CS) is a target spectrum (with conditional mean and conditional standard deviation) that links seismic hazard information with ground-motion selection for nonlinear dynamic analysis. Probabilistic seismic hazard analysis (PSHA) estimates the ground-motion hazard by incorporating the aleatory uncertainties in all earthquake scenarios and resulting ground motions, as well as the epistemic uncertainties in ground-motion prediction models (GMPMs) and seismic source models. Typical CS calculations to date are produced for a single earthquake scenario using a single GMPM, but more precise use requires consideration of at least multiple causal earthquakes and multiple GMPMs that are often considered in a PSHA computation. This paper presents the mathematics underlying these more precise CS calculations. Despite requiring more effort to compute than approximate calculations using a single causal earthquake and GMPM, the proposed approach produces an exact output that has a theoretical basis. To demonstrate the results of this approach and compare the exact and approximate calculations, several example calculations are performed for real sites in the western United States. The results also provide some insights regarding the circumstances under which approximate results are likely to closely match more exact results. To facilitate these more precise calculations for real applications, the exact CS calculations can now be performed for real sites in the United States using new deaggregation features in the U.S. Geological Survey hazard mapping tools. Details regarding this implementation are discussed in this paper.

The variation of the ground electric field associated with the Mei-Nung earthquake on Feb. 6, 2016

NASA Astrophysics Data System (ADS)

Bing-Chih Chen, Alfred; Yeh, Er-Chun; Chuang, Chia-Wen

2017-04-01

Recent studies show that a strong coupling exists between lithosphere, atmosphere and extending up to the ionosphere. Natural phenomena on the ground surface such as oceans variation, volcanic and seismic activities such as earthquakes, and lightning possibly generate significant impacts at ionosphere immediately by electrodynamic processes. The electric field near the ground is one of the potential quantities to explore this coupling process, especially caused by earthquake. Unfortunately, thunderstorm, dust storm or human activities also affect the measured electric field at ground. To investigate the feasibility of a network to monitor the variation of the ground electric field driven by the lightning and earthquake, a filed mill has been deployed in the NCKU campus since Dec. 2015, and luckily experienced the earthquake with a moment magnitude of 6.4 struck 28 km on 6 Feb. 2016. The recorded ground electric field deceased steadily since 1.5 days before the earthquake, and returned to normal level gradually. Moreover, this special feature can not be identified in the other period of the field test. The detail analysis is reported in this presentation.

Chapter A. The Loma Prieta, California, Earthquake of October 17, 1989 - Strong Ground Motion

USGS Publications Warehouse

Borcherdt, Roger D.

1994-01-01

Strong ground motion generated by the Loma Prieta, Calif., earthquake (MS~7.1) of October 17, 1989, resulted in at least 63 deaths, more than 3,757 injuries, and damage estimated to exceed $5.9 billion. Strong ground motion severely damaged critical lifelines (freeway overpasses, bridges, and pipelines), caused severe damage to poorly constructed buildings, and induced a significant number of ground failures associated with liquefaction and landsliding. It also caused a significant proportion of the damage and loss of life at distances as far as 100 km from the epicenter. Consequently, understanding the characteristics of the strong ground motion associated with the earthquake is fundamental to understanding the earthquake's devastating impact on society. The papers assembled in this chapter address this problem. Damage to vulnerable structures from the earthquake varied substantially with the distance from the causative fault and the type of underlying geologic deposits. Most of the damage and loss of life occurred in areas underlain by 'soft soil'. Quantifying these effects is important for understanding the tragic concentrations of damage in such areas as Santa Cruz and the Marina and Embarcadero Districts of San Francisco, and the failures of the San Francisco-Oakland Bay Bridge and the Interstate Highway 880 overpass. Most importantly, understanding these effects is a necessary prerequisite for improving mitigation measures for larger earthquakes likely to occur much closer to densely urbanized areas in the San Francisco Bay region. The earthquake generated an especially important data set for understanding variations in the severity of strong ground motion. Instrumental strong-motion recordings were obtained at 131 sites located from about 6 to 175 km from the rupture zone. This set of recordings, the largest yet collected for an event of this size, was obtained from sites on various geologic deposits, including a unique set on 'soft soil' deposits

Ground Motion Studies for Large Future Accelerator

NASA Astrophysics Data System (ADS)

Takeda, Shigeru; Oide, Katsunobu

1997-05-01

The future large accelerator, such as TeV linear collider, should have extremely small emittance to perform the required luminosity. Precise alignment of machine components is essential to prevent emittance dilution. The ground motion spoils alignment of accelerator elements and results in emittance growth. The ground motion in the frequency range of seismic vibration is mostly coherent in the related accelerator. But the incoherent diffusive or Brownian like motion becomes dominant at frequency region less than seismic vibration [1, 2, 3]. Slow ground motion with respect to the machine performance is discussed including the method of tunnel construction. Our experimental results and recent excavated results clarify that application of TBMs is better excavating method than NATM (Drill + Blast) for accelerator tunnel to prevent emittance dilution. ([1] V. Shiltsev, Proc. of IWAA95 Tsukuba, 1995. [2] Shigeru Takeda et al., Proc. of EPAC96, 1996. [3] A. Sery, Proc. of LINAC96, 1996.)

Geological and seismological survey for new design-basis earthquake ground motion of Kashiwazaki-Kariwa NPS

NASA Astrophysics Data System (ADS)

Takao, M.; Mizutani, H.

2009-05-01

At about 10:13 on July 16, 2007, a strong earthquake named 'Niigata-ken Chuetsu-oki Earthquake' of Mj6.8 on Japan Meteorological Agencyfs scale occurred offshore Niigata prefecture in Japan. However, all of the nuclear reactors at Kashiwazaki-Kariwa Nuclear Power Station (KKNPS) in Niigata prefecture operated by Tokyo Electric Power Company shut down safely. In other words, automatic safety function composed of shutdown, cooling and containment worked as designed immediately after the earthquake. During the earthquake, the peak acceleration of the ground motion exceeded the design-basis ground motion (DBGM), but the force due to the earthquake applied to safety-significant facilities was about the same as or less than the design basis taken into account as static seismic force. In order to assess anew the safety of nuclear power plants, we have evaluated a new DBGM after conducting geomorphological, geological, geophysical, seismological survey and analyses. [Geomorphological, Geological and Geophysical survey] In the land area, aerial photograph interpretation was performed at least within the 30km radius to extract geographies that could possibly be tectonic reliefs as a geomorphological survey. After that, geological reconnaissance was conducted to confirm whether the extracted landforms are tectonic reliefs or not. Especially we carefully investigated Nagaoka Plain Western Boundary Fault Zone (NPWBFZ), which consists of Kakuda-Yahiko fault, Kihinomiya fault and Katakai fault, because NPWBFZ is the one of the active faults which have potential of Mj8 class in Japan. In addition to the geological survey, seismic reflection prospecting of approximate 120km in total length was completed to evaluate the geological structure of the faults and to assess the consecutiveness of the component faults of NPWBFZ. As a result of geomorphological, geological and geophysical surveys, we evaluated that the three component faults of NPWBFZ are independent to each other from the

Progress report on the Worldwide Earthquake Risk Management (WWERM) Program

USGS Publications Warehouse

Algermissen, S.T.; Hays, Walter W.; Krumpe, Paul R.

1992-01-01

Considerable progress has been made in the Worldwide Earthquake Risk Management (WWERM) Program since its initiation in late 1989 as a cooperative program of the Agency for International Development (AID), Office of U.S. Foreign Disaster Assistance (OFDA), and the U.S. Geological Survey. Probabilistic peak acceleration and peak Modified Mercalli intensity (MMI) maps have been prepared for Chile and for Sulawesi province in Indonesia. Earthquake risk (loss) studies for dwellings in Gorontalo, North Sulawesi, have been completed and risk studies for dwellings in selected areas of central Chile are underway. A special study of the effect of site response on earthquake ground motion estimation in central Chile has also been completed and indicates that site response may modify the ground shaking by as much as plus or minus two units of MMI. A program for the development of national probabilistic ground motion maps for the Philippines is now underway and pilot studies of earthquake ground motion and risk are being planned for Morocco.

Structure-specific scalar intensity measures for near-source and ordinary earthquake ground motions

USGS Publications Warehouse

Luco, N.; Cornell, C.A.

2007-01-01

Introduced in this paper are several alternative ground-motion intensity measures (IMs) that are intended for use in assessing the seismic performance of a structure at a site susceptible to near-source and/or ordinary ground motions. A comparison of such IMs is facilitated by defining the "efficiency" and "sufficiency" of an IM, both of which are criteria necessary for ensuring the accuracy of the structural performance assessment. The efficiency and sufficiency of each alternative IM, which are quantified via (i) nonlinear dynamic analyses of the structure under a suite of earthquake records and (ii) linear regression analysis, are demonstrated for the drift response of three different moderate- to long-period buildings subjected to suites of ordinary and of near-source earthquake records. One of the alternative IMs in particular is found to be relatively efficient and sufficient for the range of buildings considered and for both the near-source and ordinary ground motions. ?? 2007, Earthquake Engineering Research Institute.

High Attenuation Rate for Shallow, Small Earthquakes in Japan

NASA Astrophysics Data System (ADS)

Si, Hongjun; Koketsu, Kazuki; Miyake, Hiroe

2017-09-01

We compared the attenuation characteristics of peak ground accelerations (PGAs) and velocities (PGVs) of strong motion from shallow, small earthquakes that occurred in Japan with those predicted by the equations of Si and Midorikawa (J Struct Constr Eng 523:63-70, 1999). The observed PGAs and PGVs at stations far from the seismic source decayed more rapidly than the predicted ones. The same tendencies have been reported for deep, moderate, and large earthquakes, but not for shallow, moderate, and large earthquakes. This indicates that the peak values of ground motion from shallow, small earthquakes attenuate more steeply than those from shallow, moderate or large earthquakes. To investigate the reason for this difference, we numerically simulated strong ground motion for point sources of M w 4 and 6 earthquakes using a 2D finite difference method. The analyses of the synthetic waveforms suggested that the above differences are caused by surface waves, which are predominant at stations far from the seismic source for shallow, moderate earthquakes but not for shallow, small earthquakes. Thus, although loss due to reflection at the boundaries of the discontinuous Earth structure occurs in all shallow earthquakes, the apparent attenuation rate for a moderate or large earthquake is essentially the same as that of body waves propagating in a homogeneous medium due to the dominance of surface waves.

Magnitude Estimation for Large Earthquakes from Borehole Recordings

NASA Astrophysics Data System (ADS)

Eshaghi, A.; Tiampo, K. F.; Ghofrani, H.; Atkinson, G.

2012-12-01

We present a simple and fast method for magnitude determination technique for earthquake and tsunami early warning systems based on strong ground motion prediction equations (GMPEs) in Japan. This method incorporates borehole strong motion records provided by the Kiban Kyoshin network (KiK-net) stations. We analyzed strong ground motion data from large magnitude earthquakes (5.0 ≤ M ≤ 8.1) with focal depths < 50 km and epicentral distances of up to 400 km from 1996 to 2010. Using both peak ground acceleration (PGA) and peak ground velocity (PGV) we derived GMPEs in Japan. These GMPEs are used as the basis for regional magnitude determination. Predicted magnitudes from PGA values (Mpga) and predicted magnitudes from PGV values (Mpgv) were defined. Mpga and Mpgv strongly correlate with the moment magnitude of the event, provided sufficient records for each event are available. The results show that Mpgv has a smaller standard deviation in comparison to Mpga when compared with the estimated magnitudes and provides a more accurate early assessment of earthquake magnitude. We test this new method to estimate the magnitude of the 2011 Tohoku earthquake and we present the results of this estimation. PGA and PGV from borehole recordings allow us to estimate the magnitude of this event 156 s and 105 s after the earthquake onset, respectively. We demonstrate that the incorporation of borehole strong ground-motion records immediately available after the occurrence of large earthquakes significantly increases the accuracy of earthquake magnitude estimation and the associated improvement in earthquake and tsunami early warning systems performance. Moment magnitude versus predicted magnitude (Mpga and Mpgv).

Source process of the MW7.8 2016 Kaikoura earthquake in New Zealand and the characteristics of the near-fault strong ground motion

NASA Astrophysics Data System (ADS)

Meng, L.; Zang, Y.; Zhou, L.; Han, Y.

2017-12-01

The MW7.8 New Zealand earthquake of 2016 occurred near the Kaikoura area in the South Island, New Zealand with the epicenter of 173.13°E and 42.78°S. The MW7.8 Kaikoura earthquake occurred on the transform boundary faults between the Pacific plate and the Australian plate and with the thrust focal mechanism solution. The Kaikoura earthquake is a complex event because the significant difference, especially between the magnitude, seismic moment, radiated energy and the casualties. Only two people were killed, and twenty people injured and no more than twenty buildings are destroyed during this earthquake, the damage level is not so severe in consideration about the huge magnitude. We analyzed the rupture process according to the source parameters, it can be confirmed that the radiated energy and the apparent stress of the Kaikoura earthquake are small and minor. The results indicate a frictional overshoot behavior in the dynamic source process of Kaikoura earthquake, which is actually with sufficient rupture and more affluent moderate aftershocks. It is also found that the observed horizontal Peak Ground Acceleration of the strong ground motion is generally small comparing with the Next Generation Attenuation relationship. We further studied the characteristics of the observed horizontal PGAs at the 6 near fault stations, which are located in the area less than 10 km to the main fault. The relatively high level strong ground motion from the 6 stations may be produced by the higher slip around the asperity area rather than the initial rupture position on the main plane. Actually, the huge surface displacement at the northern of the rupture fault plane indicated why aftershocks are concentrated in the north. And there are more damage in Wellington than in Christchurch, even which is near the south of the epicenter. In conclusion, the less damage level of Kaikoura earthquake in New Zealand may probably because of the smaller strong ground motion and the rare

Hazard-to-Risk: High-Performance Computing Simulations of Large Earthquake Ground Motions and Building Damage in the Near-Fault Region

NASA Astrophysics Data System (ADS)

Miah, M.; Rodgers, A. J.; McCallen, D.; Petersson, N. A.; Pitarka, A.

2017-12-01

We are running high-performance computing (HPC) simulations of ground motions for large (magnitude, M=6.5-7.0) earthquakes in the near-fault region (< 50 km) to 5 Hz and higher. Ground motions are then used as forcing functions for canonical steel moment frame buildings throughout the near-fault domain. For ground motions, we are using SW4, a fourth order summation-by-parts finite difference time-domain code running on 10,000-100,000's of cores. Earthquake ruptures are generated using the Graves and Pitarka (2017) method. We validated ground motion intensity measurements against Ground Motion Prediction Equations. We considered two events (M=6.5 and 7.0) for vertical strike-slip ruptures with three-dimensional (3D) basin structures, including stochastic heterogeneity. We have also considered M7.0 scenarios for a Hayward Fault rupture scenario which effects the San Francisco Bay Area and northern California using both 1D and 3D earth structure. Dynamic, inelastic response of canonical buildings is computed with the NEVADA, a nonlinear, finite-deformation finite element code. Canonical buildings include 3-, 9-, 20- and 40-story steel moment frame buildings. Damage potential is tracked by the peak inter-story drift (PID) ratio, which measures the maximum displacement between adjacent floors of the building and is strongly correlated with damage. PID ratios greater 1.0 generally indicate non-linear response and permanent deformation of the structure. We also track roof displacement to identify permanent deformation. PID (damage) for a given earthquake scenario (M, slip distribution, hypocenter) is spatially mapped throughout the SW4 domain with 1-2 km resolution. Results show that in the near fault region building damage is correlated with peak ground velocity (PGV), while farther away (> 20 km) it is better correlated with peak ground acceleration (PGA). We also show how simulated ground motions have peaks in the response spectra that shift to longer periods for

Strong ground motion in Port-au-Prince, Haiti, during the M7.0 12 January 2010 Haiti earthquake

USGS Publications Warehouse

Hough, Susan E; Given, Doug; Taniguchi, Tomoyo; Altidor, J.R.; Anglade, Dieuseul; Mildor, S-L.

2011-01-01

No strong motion records are available for the 12 January 2010 M7.0 Haiti earthquake. We use aftershock recordings as well as detailed considerations of damage to estimate the severity and distribution of mainshock shaking in Port-au-Prince. Relative to ground motions at a hard - rock reference site, peak accelerations are amplified by a factor of approximately 2 at sites on low-lying deposits in central Port-au-Prince and by a factor of 2.5 - 3.5 on a steep foothill ridge in the southern Port-au-Prince metropolitan region. The observed amplification along the ridge cannot be explained by sediment - induced amplification , but is consistent with predicted topographic amplification by a steep, narrow ridge. Although damage was largely a consequence of poor construction , the damage pattern inferred from analysis of remote sensing imagery provides evidence for a correspondence between small-scale (0.1 - 1.0 km) topographic relief and high damage. Mainshock shaking intensity can be estimated crudely from a consideration of macroseismic effects . We further present detailed, quantitative analysis of the marks left on a tile floor by an industrial battery rack displaced during the mainshock, at the location where we observed the highest weak motion amplifications. Results of this analysis indicate that mainshock shaking was significantly higher at this location (~0.5 g , MMI VIII) relative to the shaking in parts of Port-au-Prince that experienced light damage. Our results further illustrate how observations of rigid body horizontal displacement during earthquakes can be used to estimate peak ground accelerations in the absence of instrumental data .

Prediction of Strong Earthquake Ground Motion for the M=7.4 and M=7.2 1999, Turkey Earthquakes based upon Geological Structure Modeling and Local Earthquake Recordings

NASA Astrophysics Data System (ADS)

Gok, R.; Hutchings, L.

2004-05-01

We test a means to predict strong ground motion using the Mw=7.4 and Mw=7.2 1999 Izmit and Duzce, Turkey earthquakes. We generate 100 rupture scenarios for each earthquake, constrained by a prior knowledge, and use these to synthesize strong ground motion and make the prediction. Ground motion is synthesized with the representation relation using impulsive point source Green's functions and synthetic source models. We synthesize the earthquakes from DC to 25 Hz. We demonstrate how to incorporate this approach into standard probabilistic seismic hazard analyses (PSHA). The synthesis of earthquakes is based upon analysis of over 3,000 aftershocks recorded by several seismic networks. The analysis provides source parameters of the aftershocks; records available for use as empirical Green's functions; and a three-dimensional velocity structure from tomographic inversion. The velocity model is linked to a finite difference wave propagation code (E3D, Larsen 1998) to generate synthetic Green's functions (DC < f < 0.5 Hz). We performed the simultaneous inversion for hypocenter locations and three-dimensional P-wave velocity structure of the Marmara region using SIMULPS14 along with 2,500 events. We also obtained source moment and corner frequency and individual station attenuation parameter estimates for over 500 events by performing a simultaneous inversion to fit these parameters with a Brune source model. We used the results of the source inversion to deconvolve out a Brune model from small to moderate size earthquake (M<4.0) recordings to obtain empirical Green's functions for the higher frequency range of ground motion (0.5 < f < 25.0 Hz). Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract W-7405-ENG-48.

3D Ground-Motion Simulations for Magnitude 9 Earthquakes on the Cascadia Megathrust: Sedimentary Basin Amplification, Rupture Directivity, and Ground-Motion Variability

NASA Astrophysics Data System (ADS)

Frankel, A. D.; Wirth, E. A.; Marafi, N.; Vidale, J. E.; Stephenson, W. J.

2017-12-01

We have produced broadband (0-10 Hz) synthetic seismograms for Mw 9 earthquakes on the Cascadia subduction zone by combining synthetics from 3D finite-difference simulations at low frequencies (≤ 1 Hz) and stochastic synthetics at high frequencies (≥ 1 Hz). These synthetic ground motions are being used to evaluate building response, liquefaction, and landslides, as part of the M9 Project of the University of Washington, in collaboration with the U.S. Geological Survey. The kinematic rupture model is composed of high stress drop sub-events with Mw 8, similar to those observed in the Mw 9.0 Tohoku, Japan and Mw 8.8 Maule, Chile earthquakes, superimposed on large background slip with lower slip velocities. The 3D velocity model is based on active and passive-source seismic tomography studies, seismic refraction and reflection surveys, and geologic constraints. The Seattle basin portion of the model has been validated by simulating ground motions from local earthquakes. We have completed 50 3D simulations of Mw 9 earthquakes using a variety of hypocenters, slip distributions, sub-event locations, down-dip limits of rupture, and other parameters. For sites not in deep sedimentary basins, the response spectra of the synthetics for 0.1-6.0 s are similar, on average, to the values from the BC Hydro ground motion prediction equations (GMPE). For periods of 7-10 s, the synthetic response spectra exceed these GMPE, partially due to the shallow dip of the plate interface. We find large amplification factors of 2-5 for response spectra at periods of 1-10 s for locations in the Seattle and Tacoma basins, relative to sites outside the basins. This amplification depends on the direction of incoming waves and rupture directivity. The basin amplification is caused by surface waves generated at basin edges from incoming S-waves, as well as amplification and focusing of S-waves and surface waves by the 3D basin structure. The inter-event standard deviation of response spectral

Trampoline effect in extreme ground motion.

PubMed

Aoi, Shin; Kunugi, Takashi; Fujiwara, Hiroyuki

2008-10-31

In earthquake hazard assessment studies, the focus is usually on horizontal ground motion. However, records from the 14 June 2008 Iwate-Miyagi earthquake in Japan, a crustal event with a moment magnitude of 6.9, revealed an unprecedented vertical surface acceleration of nearly four times gravity, more than twice its horizontal counterpart. The vertical acceleration was distinctly asymmetric; the waveform envelope was about 1.6 times as large in the upward direction as in the downward direction, which is not explained by existing models of the soil response. We present a simple model of a mass bouncing on a trampoline to account for this asymmetry and the large vertical amplitude. The finding of a hitherto-unknown mode of strong ground motion may prompt major progress in near-source shaking assessments.

Earthquake precursors from InSAR geodesy: insights from the L'Aquila (Central Italy) April 6, 2009 earthquake

NASA Astrophysics Data System (ADS)

Bignami, C.; Moro, M.; Saroli, M.; Stramondo, S.; Albano, M.; Falcucci, E.; Gori, S.; Doglioni, C.; Polcari, M.; Tallini, M.; Macerola, L.; Novali, F.; Costantini, M.; Malvarosa, F.; Wegmüller, U.

2017-12-01

In modern seismology, the identification of earthquake precursors is one of the most important issue to investigate on. Precursor indicators based on the use of updated and most satellite advanced geodetic techniques such as GPS and SAR interferometry, have not been conclusively identified so far. However, the latest progress in terms of new satellite missions and processing algorithms may bring this goal closer. Here we present evidence of ground deformation signals preceding the 2009 L'Aquila earthquake, which have been observed using multi-temporal InSAR techniques. We exploited a wide dataset from RADARSAT2, ENVISAT and COSMO-SkyMed missions to derive mean velocity and ground acceleration maps of the epicentral area, for a time span of approximately 6 years before the earthquake and about one year after the earthquake. The maps of ground accelerations before the mainshock, have allowed the identification of two peculiar displacement patterns, well localized in two Quaternary basins, close to the focal volume of the seismic event (Mw 6.3) that hit the city of L'Aquila on 6 April 2009. In these two regions, a significant subsidence began approximately three years before the earthquake, reaching a value of about 1.5 cm, and persisted until the earthquake. Conversely, in the post-seismic phase, the two basins showed an uplift, with velocities approximately of 5 to 18 mm/yr. The deep knowledge of the geological, hydrogeological and geotechnical setting of the area has provided a plausible explanation of the observed phenomenon. The two Quaternary basins are filled with sediments that host multi-layer aquifers that are hydrologically connected with the neighbouring carbonatic hydrostructures. Before the earthquake, the rocks at depth have dilated and fractures opened. Consequently, fluids have migrated into the dilated volume causing the lowering the groundwater table in the carbonate hydrostructures and in the hydrologically connected multi-layer aquifers within the

Rotation of vertically oriented objects during earthquakes

NASA Astrophysics Data System (ADS)

Hinzen, Klaus-G.

2012-10-01

Vertically oriented objects, such as tombstones, monuments, columns, and stone lanterns, are often observed to shift and rotate during earthquake ground motion. Such observations are usually limited to the mesoseismal zone. Whether near-field rotational ground motion components are necessary in addition to pure translational movements to explain the observed rotations is an open question. We summarize rotation data from seven earthquakes between 1925 and 2009 and perform analog and numeric rotation testing with vertically oriented objects. The free-rocking motion of a marble block on a sliding table is disturbed by a pulse in the direction orthogonal to the rocking motion. When the impulse is sufficiently strong and occurs at the `right' moment, it induces significant rotation of the block. Numeric experiments of a free-rocking block show that the initiation of vertical block rotation by a cycloidal acceleration pulse applied orthogonal to the rocking axis depends on the amplitude of the pulse and its phase relation to the rocking cycle. Rotation occurs when the pulse acceleration exceeds the threshold necessary to provoke rocking of a resting block, and the rocking block approaches its equilibrium position. Experiments with blocks subjected to full 3D strong motion signals measured during the 2009 L'Aquila earthquake confirm the observations from the tests with analytic ground motions. Significant differences in the rotational behavior of a monolithic block and two stacked blocks exist.

Characteristics of strong motions and damage implications of M S6.5 Ludian earthquake on August 3, 2014

NASA Astrophysics Data System (ADS)

Xu, Peibin; Wen, Ruizhi; Wang, Hongwei; Ji, Kun; Ren, Yefei

2015-02-01

The Ludian County of Yunnan Province in southwestern China was struck by an M S6.5 earthquake on August 3, 2014, which was another destructive event following the M S8.0 Wenchuan earthquake in 2008, M S7.1 Yushu earthquake in 2010, and M S7.0 Lushan earthquake in 2013. National Strong-Motion Observation Network System of China collected 74 strong motion recordings, which the maximum peak ground acceleration recorded by the 053LLT station in Longtoushan Town was 949 cm/s2 in E-W component. The observed PGAs and spectral ordinates were compared with ground-motion prediction equation in China and the NGA-West2 developed by Pacific Earthquake Engineering Researcher Center. This earthquake is considered as the first case for testing applicability of NGA-West2 in China. Results indicate that the observed PGAs and the 5 % damped pseudo-response spectral accelerations are significantly lower than the predicted ones. The field survey around some typical strong motion stations verified that the earthquake damage was consistent with the official isoseismal by China Earthquake Administration.

Comparisons of ground motions from five aftershocks of the 1999 Chi-Chi, Taiwan, earthquake with empirical predictions largely based on data from California

USGS Publications Warehouse

Wang, G.-Q.; Boore, D.M.; Igel, H.; Zhou, X.-Y.

2004-01-01

The observed ground motions from five large aftershocks of the 1999 Chi-Chi, Taiwan, earthquake are compared with predictions from four equations based primarily on data from California. The four equations for active tectonic regions are those developed by Abrahamson and Silva (1997), Boore et al. (1997), Campbell (1997, 2001), and Sadigh et al. (1997). Comparisons are made for horizontal-component peak ground accelerations and 5%-damped pseudoacceleration response spectra at periods between 0.02 sec and 5 sec. The observed motions are in reasonable agreement with the predictions, particularly for distances from 10 to 30 km. This is in marked contrast to the motions from the Chi-Chi mainshock, which are much lower than the predicted motions for periods less than about 1 sec. The results indicate that the low motions in the mainshock are not due to unusual, localized absorption of seismic energy, because waves from the mainshock and the aftershocks generally traverse the same section of the crust and are recorded at the same stations. The aftershock motions at distances of 30-60 km are somewhat lower than the predictions (but not nearly by as small a factor as those for the mainshock), suggesting that the ground motion attenuates more rapidly in this region of Taiwan than it does in the areas we compare with it. We provide equations for the regional attenuation of response spectra, which show increasing decay of motion with distance for decreasing oscillator periods. This observational study also demonstrates that ground motions have large earthquake-location-dependent variability for a specific site. This variability reduces the accuracy with which an earthquake-specific prediction of site response can be predicted. Online Material: PGAs and PSAs from the 1999 Chi-Chi earthquake and five aftershocks.

Earthquake cycle modeling of multi-segmented faults: dynamic rupture and ground motion simulation of the 1992 Mw 7.3 Landers earthquake.

NASA Astrophysics Data System (ADS)

Petukhin, A.; Galvez, P.; Somerville, P.; Ampuero, J. P.

2017-12-01

We perform earthquake cycle simulations to study the characteristics of source scaling relations and strong ground motions and in multi-segmented fault ruptures. For earthquake cycle modeling, a quasi-dynamic solver (QDYN, Luo et al, 2016) is used to nucleate events and the fully dynamic solver (SPECFEM3D, Galvez et al., 2014, 2016) is used to simulate earthquake ruptures. The Mw 7.3 Landers earthquake has been chosen as a target earthquake to validate our methodology. The SCEC fault geometry for the three-segmented Landers rupture is included and extended at both ends to a total length of 200 km. We followed the 2-D spatial correlated Dc distributions based on Hillers et. al. (2007) that associates Dc distribution with different degrees of fault maturity. The fault maturity is related to the variability of Dc on a microscopic scale. Large variations of Dc represents immature faults and lower variations of Dc represents mature faults. Moreover we impose a taper (a-b) at the fault edges and limit the fault depth to 15 km. Using these settings, earthquake cycle simulations are performed to nucleate seismic events on different sections of the fault, and dynamic rupture modeling is used to propagate the ruptures. The fault segmentation brings complexity into the rupture process. For instance, the change of strike between fault segments enhances strong variations of stress. In fact, Oglesby and Mai (2012) show the normal stress varies from positive (clamping) to negative (unclamping) between fault segments, which leads to favorable or unfavorable conditions for rupture growth. To replicate these complexities and the effect of fault segmentation in the rupture process, we perform earthquake cycles with dynamic rupture modeling and generate events similar to the Mw 7.3 Landers earthquake. We extract the asperities of these events and analyze the scaling relations between rupture area, average slip and combined area of asperities versus moment magnitude. Finally, the

Broadband Ground Motion Observation and Simulation for the 2016 Kumamoto Earthquake

NASA Astrophysics Data System (ADS)

Miyake, H.; Chimoto, K.; Yamanaka, H.; Tsuno, S.; Korenaga, M.; Yamada, N.; Matsushima, T.; Miyakawa, K.

2016-12-01

During the 2016 Kumamoto earthquake, strong motion data were widely recorded by the permanent dense triggered strong motion network of K-NET/KiK-net and seismic intensity meters installed by local government and JMA. Seismic intensities close to the MMI 9-10 are recorded twice at the Mashiki town, and once at the Nishihara village and KiK-net Mashiki (KMMH16 ground surface). Near-fault records indicate extreme ground motion exceeding 400 cm/s in 5% pSv at a period of 1 s for the Mashiki town and 3-4 s for the Nishihara village. Fault parallel velocity components are larger between the Mashiki town and the Nishihara village, on the other hand, fault normal velocity components are larger inside the caldera of the Aso volcano. The former indicates rupture passed through along-strike stations, and the latter stations located at the forward rupture direction (e.g., Miyatake, 1999). In addition to the permanent observation, temporary continuous strong motion stations were installed just after the earthquake in the Kumamoto city, Mashiki town, Nishihara village, Minami-Aso village, and Aso town, (e.g., Chimoto et al., 2016; Tsuno et al., 2016; Yamanaka et al. 2016). This study performs to estimate strong motion generation areas for the 2016 Kumamoto earthquake sequence using the empirical Green's function method, then to simulate broadband ground motions for both the permanent and temporary strong motion stations. Currently the target period range is between 0.1 s to 5-10 s due to the signal-to-noise ratio of element earthquakes used for the empirical Green's functions. We also care fault dimension parameters N within 4 to 10 to avoid spectral sags and artificial periodicity. The simulated seismic intensities as well as fault normal and parallel velocity components will be discussed.

Precarious rock and overturned transformer evidence for ground shaking in the Ms 7.7 Kern County earthquake: An analog for disastrous shaking from a major thrust fault in the Los Angeles basin

USGS Publications Warehouse

Brune, J.N.; Anooshehpoor, A.; Shi, B.; Zheng, Yen

2004-01-01

Precariously balanced rocks and overturned transformers in the vicinity of the White Wolf fault provide constraints on ground motion during the 1952 Ms 7.7 Kern County earthquake, a possible analog for an anticipated large earthquake in the Los Angeles basin (Shaw et al., 2002; Dolan et al., 2003). On the northeast part of the fault preliminary estimates of ground motion on the footwall give peak accelerations considerably lower than predicted by standard regression curves. On the other hand, on the hanging-wall, there is evidence of intense ground shattering and lack of precarious rocks, consistent with the intense hanging-wall accelerations suggested by foam-rubber modeling, numerical modeling, and observations from previous thrust fault earthquakes. There is clear evidence of the effects of rupture directivity in ground motions on the hanging-wall side of the fault (from both precarious rocks and numerical simulations). On the southwest part of the fault, which is covered by sediments, the thrust fault did not reach the surface ("blind" thrust). Overturned and damaged transformers indicate significant transfer of energy from the hanging wall to the footwall, an effect that may not be as effective when the rupture reaches the surface (is not "blind"). Transformers near the up-dip projection of the fault tip have been damaged or overturned on both the hanging-wall and footwall sides of the fault. The transfer of energy is confirmed in a numerical lattice model and could play an important role in a similar situation in Los Angeles. We suggest that the results of this study can provide important information for estimating the effects of a large thrust fault rupture in the Los Angeles basin, specially given the fact that there is so little instrumental data from large thrust fault earthquakes.

Ground-motion modeling of the 1906 San Francisco earthquake, part I: Validation using the 1989 Loma Prieta earthquake

USGS Publications Warehouse

Aagaard, Brad T.; Brocher, T.M.; Dolenc, D.; Dreger, D.; Graves, R.W.; Harmsen, S.; Hartzell, S.; Larsen, S.; Zoback, M.L.

2008-01-01

We compute ground motions for the Beroza (1991) and Wald et al. (1991) source models of the 1989 magnitude 6.9 Loma Prieta earthquake using four different wave-propagation codes and recently developed 3D geologic and seismic velocity models. In preparation for modeling the 1906 San Francisco earthquake, we use this well-recorded earthquake to characterize how well our ground-motion simulations reproduce the observed shaking intensities and amplitude and durations of recorded motions throughout the San Francisco Bay Area. All of the simulations generate ground motions consistent with the large-scale spatial variations in shaking associated with rupture directivity and the geologic structure. We attribute the small variations among the synthetics to the minimum shear-wave speed permitted in the simulations and how they accommodate topography. Our long-period simulations, on average, under predict shaking intensities by about one-half modified Mercalli intensity (MMI) units (25%-35% in peak velocity), while our broadband simulations, on average, under predict the shaking intensities by one-fourth MMI units (16% in peak velocity). Discrepancies with observations arise due to errors in the source models and geologic structure. The consistency in the synthetic waveforms across the wave-propagation codes for a given source model suggests the uncertainty in the source parameters tends to exceed the uncertainty in the seismic velocity structure. In agreement with earlier studies, we find that a source model with slip more evenly distributed northwest and southeast of the hypocenter would be preferable to both the Beroza and Wald source models. Although the new 3D seismic velocity model improves upon previous velocity models, we identify two areas needing improvement. Nevertheless, we find that the seismic velocity model and the wave-propagation codes are suitable for modeling the 1906 earthquake and scenario events in the San Francisco Bay Area.

Ground motions estimates for a cascadia earthquake from liquefaction evidence

USGS Publications Warehouse

Dickenson, S.E.; Obermeier, S.F.

1998-01-01

Paleoseismic studies conducted in the coastal regions of the Pacific Northwest in the past decade have revealed evidence of crustal downdropping and subsequent tsunami inundation, attributable to a large earthquake along the Cascadia subduction zone which occurred approximately 300 years ago, and most likely in 1700 AD. In order to characterize the severity of ground motions from this earthquake, we report on results of a field search for seismically induced liquefaction features. The search was made chiefly along the coastal portions of several river valleys in Washington, rivers along the central Oregon coast, as well as on islands in the Columbia River of Oregon and Washington. In this paper we focus only on the results of the Columbia River investigation. Numerous liquefaction features were found in some regions, but not in others. The regional distribution of liquefaction features is evaluated as a function of geologic and geotechnical factors at each site in order to estimate the intensity of ground shaking.

Imprint of Rupture Directivity From Ground Motions of the 24 August 2016 Mw6.2 Central Italy Earthquake

NASA Astrophysics Data System (ADS)

Ren, Yefei; Wang, Hongwei; Wen, Ruizhi

2017-12-01

An Mw6.2 earthquake occurred in Central Italy on 24 August 2016. The objective of this study was to reveal the imprint of rupture directivity using the strong motion recordings. The strong motion stations were separated into two groups: southeast (SE) and northwest (NW). The effects of rupture directivity on the peak ground acceleration (PGA), peak ground velocity (PGV), and pseudo spectral acceleration (PSA) were investigated. The observed values of these parameters were compared with predicted values derived from ground motion prediction equations. The results showed that the residuals between the observed and predicted PGAs, PGVs, and PSAs at periods of T < 1 s were correlated significantly with azimuth angle and generally larger in the NW sector, reflecting that the observed PGAs, PGVs, and short-period PSAs in the NW sector were generally larger than observed in the SE sector. These phenomena are accordant with the theoretical law that the rupture directivity causes higher amplitudes in the forward direction compared with the backward direction. Finally, selected source rupture parameters were inverted using PGAs and PGVs. This revealed that the rupture was predominantly unilateral rupture, the major rupture was likely at an azimuth of 360°, and the length of the major rupture was proportional to 70%-100% of the total ruptured fault, confirming that rupture directivity caused the differences in the ground motions observed in the SE and NW sectors.

Stochastic ground-motion simulation of two Himalayan earthquakes: seismic hazard assessment perspective

NASA Astrophysics Data System (ADS)

Harbindu, Ashish; Sharma, Mukat Lal; Kamal

2012-04-01

The earthquakes in Uttarkashi (October 20, 1991, M w 6.8) and Chamoli (March 8, 1999, M w 6.4) are among the recent well-documented earthquakes that occurred in the Garhwal region of India and that caused extensive damage as well as loss of life. Using strong-motion data of these two earthquakes, we estimate their source, path, and site parameters. The quality factor ( Q β ) as a function of frequency is derived as Q β ( f) = 140 f 1.018. The site amplification functions are evaluated using the horizontal-to-vertical spectral ratio technique. The ground motions of the Uttarkashi and Chamoli earthquakes are simulated using the stochastic method of Boore (Bull Seismol Soc Am 73:1865-1894, 1983). The estimated source, path, and site parameters are used as input for the simulation. The simulated time histories are generated for a few stations and compared with the observed data. The simulated response spectra at 5% damping are in fair agreement with the observed response spectra for most of the stations over a wide range of frequencies. Residual trends closely match the observed and simulated response spectra. The synthetic data are in rough agreement with the ground-motion attenuation equation available for the Himalayas (Sharma, Bull Seismol Soc Am 98:1063-1069, 1998).

Moment Magnitudes and Local Magnitudes for Small Earthquakes: Implications for Ground-Motion Prediction and b-values

NASA Astrophysics Data System (ADS)

Baltay, A.; Hanks, T. C.; Vernon, F.

2016-12-01

We illustrate two essential consequences of the systematic difference between moment magnitude and local magnitude for small earthquakes, illuminating the underlying earthquake physics. Moment magnitude, M 2/3 log M0, is uniformly valid for all earthquake sizes [Hanks and Kanamori, 1979]. However, the relationship between local magnitude ML and moment is itself magnitude dependent. For moderate events, 3< M < 7, M and M­L are coincident; for earthquakes smaller than M3, ML log M0 [Hanks and Boore, 1984]. This is a consequence of the saturation of the apparent corner frequency fc as it becoming greater than the largest observable frequency, fmax; In this regime, stress drop no longer controls ground motion. This implies that ML and M differ by a factor of 1.5 for these small events. While this idea is not new, its implications are important as more small-magnitude data are incorporated into earthquake hazard research. With a large dataset of M<3 earthquakes recorded on the ANZA network, we demonstrate striking consequences of the difference between M and ML. ML scales as the log peak ground motions (e.g., PGA or PGV) for these small earthquakes, which yields log PGA log M0 [Boore, 1986]. We plot nearly 15,000 records of PGA and PGV at close stations, adjusted for site conditions and for geometrical spreading to 10 km. The slope of the log of ground motion is 1.0*ML­, or 1.5*M, confirming the relationship, and that fc >> fmax. Just as importantly, if this relation is overlooked, prediction of large-magnitude ground motion from small earthquakes will be misguided. We also consider the effect of this magnitude scale difference on b-value. The oft-cited b-value of 1 should hold for small magnitudes, given M. Use of ML necessitates b=2/3 for the same data set; use of mixed, or unknown, magnitudes complicates the matter further. This is of particular import when estimating the rate of large earthquakes when one has limited data on their recurrence, as is the case for

ANALYSIS ON THE GROUND DESTROYED FEATURES AND TECTONIC STRESS FIELD OF THE 2008 WENCHUAN EARTHQUAKE AND OUR TREATING TACTICS

NASA Astrophysics Data System (ADS)

Guo, Y.; Wang, H.; Deng, Z.; You, H.

2009-12-01

To research the ground destroyed features and tectonic stress field of the 2008 Wenchuan Earthquake, we went the earthquake-hazard area, Hongkou Town in Dujiangyan City, Yingxiu Town in Wenchuan County, Bailu Town in Pengzhou City, Yinghua Town in Shifang City, Hanwang Town in Mianzhu City and Beichuan Cit early and late twice in 2008. The geological survey was made. Firstly, the ground destroyed features of the Wenchuan Earthquake around both Yingxiu - Beichuan Fracture and Guanxian - Jiangyou Fracture were analyzed. They mainly display as the ground crack ground, road steep slope, ground deformation, road rise high and deformation, road staggering and rupture, etc. Besides, the Wenchuan Earthquake resulted in the great deal of building collapse and lots of bridges damage even break down; It can be seen that the first floor of the building disappeared or damaged seriously; Some building still stood there although damaged by the earthquake; A few of building was damaged slightly and kept intact structure. Furthermore, the earthquake caused earth slide, mudflow and rolling stone, which lead to the building destroyed seriously, river blocked up, the life line engineering destroyed. Secondly, the phenomena of the ground destroy were analyzed preliminarily. The seismic intensity was determined based on the field investigation. The damaged situation of the construction was concluded. Based on the principle of structure geology and making use of the Stereographic projection, the stress field was analyzed according to the attitude, structural nature and relations among the fracture, fault scratch and joint fissure as well as the characteristics of ground deformation thirdly. The geodynamics of the 2008 Wenchuan Earthquake are probed into preliminarily. The main compressive stress (the maximum main stress) σ1 took Northeast by east direction, and the main tensile stress (the minimum main stress)σ3 took Northwest by north direction. The main fracture shows as the right

A New Network-Based Approach for the Earthquake Early Warning

NASA Astrophysics Data System (ADS)

Alessandro, C.; Zollo, A.; Colombelli, S.; Elia, L.

2017-12-01

Here we propose a new method which allows for issuing an early warning based upon the real-time mapping of the Potential Damage Zone (PDZ), e.g. the epicentral area where the peak ground velocity is expected to exceed the damaging or strong shaking levels with no assumption about the earthquake rupture extent and spatial variability of ground motion. The system includes the techniques for a refined estimation of the main source parameters (earthquake location and magnitude) and for an accurate prediction of the expected ground shaking level. The system processes the 3-component, real-time ground acceleration and velocity data streams at each station. For stations providing high quality data, the characteristic P-wave period (τc) and the P-wave displacement, velocity and acceleration amplitudes (Pd, Pv and Pa) are jointly measured on a progressively expanded P-wave time window. The evolutionary estimate of these parameters at stations around the source allow to predict the geometry and extent of PDZ, but also of the lower shaking intensity regions at larger epicentral distances. This is done by correlating the measured P-wave amplitude with the Peak Ground Velocity (PGV) and Instrumental Intensity (IMM) and by interpolating the measured and predicted P-wave amplitude at a dense spatial grid, including the nodes of the accelerometer/velocimeter array deployed in the earthquake source area. Depending of the network density and spatial source coverage, this method naturally accounts for effects related to the earthquake rupture extent (e.g. source directivity) and spatial variability of strong ground motion related to crustal wave propagation and site amplification. We have tested this system by a retrospective analysis of three earthquakes: 2016 Italy 6.5 Mw, 2008 Iwate-Miyagi 6.9 Mw and 2011 Tohoku 9.0 Mw. Source parameters characterization are stable and reliable, also the intensity map shows extended source effects consistent with kinematic fracture models of

Fast Identification of Near-Trench Earthquakes Along the Mexican Subduction Zone Based on Characteristics of Ground Motion in Mexico City

NASA Astrophysics Data System (ADS)

Perez-Campos, X.; Singh, S. K.; Arroyo, D.; Rodríguez, Q.; Iglesias, A.

2015-12-01

The disastrous 1985 Michoacan earthquake gave rise to a seismic alert system for Mexico City which became operational in 1991. Initially limited to earthquakes along the Guerrero coast, the system now has a much wider coverage. Also, the 2004 Sumatra earthquake exposed the need for a tsunami early warning along the Mexican subduction zone. A fast identification of near-trench earthquakes along this zone may be useful in issuing a reliable early tsunami alert. The confusion caused by low PGA for the magnitude of an earthquake, leading to "missed" seismic alert, would be averted if its near-trench origin can be quickly established. It may also help reveal the spatial extent and degree of seismic coupling on the near-trench portion of the plate interface. This would lead to a better understanding of tsunami potential and seismic hazard along the Mexican subduction zone. We explore three methods for quick detection of near-trench earthquakes, testing them on recordings of 65 earthquakes at station CU in Mexico City (4.8 ≤Mw≤8.0; 270≤R≤615 km). The first method is based on the ratio of total to high-frequency energy, ER (Shapiro et al., 1998). The second method is based on parameter Sa*(6) which is the pseudo-acceleration response spectrum with 5% damping, Sa, at 6 s normalized by the PGA. The third parameter is the PGA residual, RESN, at CU, with respect to a newly-derived ground motion prediction equation at CU for coastal shallow-dipping thrust earthquakes following a bayesian approach. Since the near-trench earthquakes are relatively deficient in high-frequency radiation, we expect ER and Sa*(6) to be relatively large and RESN to be negative for such events. Tests on CU recordings show that if ER ≥ 100 and/or Sa*(6) ≥ 0.70, then the earthquake is near trench; for these events RESN ≤ 0. Such an event has greater tsunami potential. Few misidentifications and missed events are most probably a consequence of poor location, although unusual depth and source

Source parameters of the 2013 Lushan, Sichuan, Ms7.0 earthquake and estimation of the near-fault strong ground motion

NASA Astrophysics Data System (ADS)

Meng, L.; Zhou, L.; Liu, J.

2013-12-01

Abstract: The April 20, 2013 Ms 7.0 earthquake in Lushan city, Sichuan province of China occurred as the result of east-west oriented reverse-type motion on a north-south striking fault. The source location suggests the event occurred on the Southern part of Longmenshan fault at a depth of 13km. The Lushan earthquake caused a great of loss of property and 196 deaths. The maximum intensity is up to VIII to IX at Boxing and Lushan city, which are located in the meizoseismal area. In this study, we analyzed the dynamic source process and calculated source spectral parameters, estimated the strong ground motion in the near-fault field based on the Brune's circle model at first. A dynamical composite source model (DCSM) has been developed further to simulate the near-fault strong ground motion with associated fault rupture properties at Boxing and Lushan city, respectively. The results indicate that the frictional undershoot behavior in the dynamic source process of Lushan earthquake, which is actually different from the overshoot activity of the Wenchuan earthquake. Based on the simulated results of the near-fault strong ground motion, described the intensity distribution of the Lushan earthquake field. The simulated intensity indicated that, the maximum intensity value is IX, and region with and above VII almost 16,000km2, which is consistence with observation intensity published online by China Earthquake Administration (CEA) on April 25. Moreover, the numerical modeling developed in this study has great application in the strong ground motion prediction and intensity estimation for the earthquake rescue purpose. In fact, the estimation methods based on the empirical relationship and numerical modeling developed in this study has great application in the strong ground motion prediction for the earthquake source process understand purpose. Keywords: Lushan, Ms7.0 earthquake; near-fault strong ground motion; DCSM; simulated intensity

Forecast model for great earthquakes at the Nankai Trough subduction zone

USGS Publications Warehouse

Stuart, W.D.

1988-01-01

An earthquake instability model is formulated for recurring great earthquakes at the Nankai Trough subduction zone in southwest Japan. The model is quasistatic, two-dimensional, and has a displacement and velocity dependent constitutive law applied at the fault plane. A constant rate of fault slip at depth represents forcing due to relative motion of the Philippine Sea and Eurasian plates. The model simulates fault slip and stress for all parts of repeated earthquake cycles, including post-, inter-, pre- and coseismic stages. Calculated ground uplift is in agreement with most of the main features of elevation changes observed before and after the M=8.1 1946 Nankaido earthquake. In model simulations, accelerating fault slip has two time-scales. The first time-scale is several years long and is interpreted as an intermediate-term precursor. The second time-scale is a few days long and is interpreted as a short-term precursor. Accelerating fault slip on both time-scales causes anomalous elevation changes of the ground surface over the fault plane of 100 mm or less within 50 km of the fault trace. ?? 1988 Birkha??user Verlag.

Recovery of Near-Fault Ground Motion by Introducing Rotational Motions

NASA Astrophysics Data System (ADS)

Chiu, H. C.

2014-12-01

Near-fault ground motion is the key data to seismologists for revealing the seismic faulting and earthquake physics and strong-motion data is the only near-fault seismogram that can keep on-scale recording in a major earthquake. Unfortunately, this type of data might be contaminated by the rotation induced effects such as the centrifugal acceleration and the gravity effects. We analyze these effects based on a set of collocated rotation-translation data of small to moderate earthquakes. Results show these rotation effects could be negligible in small ground motion, but they might have a radical growing in the near-fault/extremely large ground motions. In order to extract more information from near-fault seismogram for improving our understating of seismic faulting and earthquake physics, it requires six-component collocated rotation-translation records to reduce or remove these effects.

The Long-term Impacts of Earthquakes on Economic Growth

NASA Astrophysics Data System (ADS)

Lackner, S.

2016-12-01

The social science literature has so far not reached a consensus on whether and how earthquakes actually impact economic growth in the long-run. Several hypotheses have been suggested and some even argue for a positive impact. A general weakness in the literature, however, is the predominant use of inadequate measures for the exogenous natural hazard of an earthquake. The most common problems are the lack of individual event size (e.g. earthquake dummy or number of events), the use of magnitude instead of a measure for surface shaking, and endogeneity issues when traditional qualitative intensity scales or actual impact data is used. Here we use peak ground acceleration (PGA) as the ground motion intensity measure and investigate the impacts of earthquake shaking on long-run economic growth. We construct a data set from USGS ShakeMaps that can be considered the universe of global relevant earthquake ground shaking from 1973 to 2014. This data set is then combined with World Bank GDP data to conduct a regression analysis. Furthermore, the impacts of PGA on different industries and other economic variables such as employment and education are also investigated. This will on one hand help to identify the mechanism of how earthquakes impact long-run growth and also show potential impacts on other welfare indicators that are not captured by GDP. This is the first application of global earthquake shaking data to investigate long-term earthquake impacts.

8 March 2010 Elazığ-Kovancilar (Turkey) Earthquake: observations on ground motions and building damage

USGS Publications Warehouse

Akkar, Sinan; Aldemir, A.; Askan, A.; Bakir, S.; Canbay, E.; Demirel, I.O.; Erberik, M.A.; Gulerce, Z.; Gulkan, Polat; Kalkan, Erol; Prakash, S.; Sandikkaya, M.A.; Sevilgen, V.; Ugurhan, B.; Yenier, E.

2011-01-01

An earthquake of MW = 6.1 occurred in the Elazığ region of eastern Turkey on 8 March 2010 at 02:32:34 UTC. The United States Geological Survey (USGS) reported the epicenter of the earthquake as 38.873°N-39.981°E with a focal depth of 12 km. Forty-two people lost their lives and 137 were injured during the event. The earthquake was reported to be on the left-lateral strike-slip east Anatolian fault (EAF), which is one of the two major active fault systems in Turkey. Teams from the Earthquake Engineering Research Center of the Middle East Technical University (EERC-METU) visited the earthquake area in the aftermath of the mainshock. Their reconnaissance observations were combined with interpretations of recorded ground motions for completeness. This article summarizes observations on building and ground damage in the area and provides a discussion of the recorded motions. No significant observations in terms of geotechnical engineering were made.

The persistence of directivity in small earthquakes

USGS Publications Warehouse

Boatwright, J.

2007-01-01

We derive a simple inversion of peak ground acceleration (PGA) or peak ground velocity (PGV) for rupture direction and rupture velocity and then test this inversion on the peak motions obtained from seven 3.5 ??? M ??? 4.1 earthquakes that occurred in two clusters in November 2002 and February 2003 near San Ramon, California. These clusters were located on two orthogonal strike-slip faults so that the events share the same approximate focal mechanism but not the same fault plane. Three earthquakes exhibit strong directivity, but the other four earthquakes exhibit relatively weak directivity. We use the residual PGAs and PGVs from the other six events to determine station corrections for each earthquake. The inferred rupture directions unambiguously identify the fault plane for the three earthquakes with strong directivity and for three of the four earthquakes with weak directivity. The events with strong directivity have fast rupture velocities (0.63????? v ??? 0.87??); the events with weak directivity either rupture more slowly (0.17????? v ???0.35??) or bilaterally. The simple unilateral inversion cannot distinguish between slow and bilateral ruptures: adding a bilateral rupture component degrades the fit of the rupture directions to the fault planes. By comparing PGAs from the events with strong and weak directivity, we show how an up-dip rupture in small events can distort the attenuation of peak ground motion with distance. When we compare the rupture directions of the earthquakes to the location of aftershocks in the two clusters, we find than almost all the aftershocks of the three earthquakes with strong directivity occur within 70?? of the direction of rupture.

Ground Motion in Lima: Pisco Earthquake of August 15, 2007 (Mw7.9)

NASA Astrophysics Data System (ADS)

Bernal, I.; Tavera, H.

2008-05-01

On 15 of August of 2007 at 06h 40min, local time, the central region of Peru was shooked by an earthquake magnitude Mw=7.9 with epicenter at 13.49°S and -76.85°W; this is, 74 km west of the city of Pisco. The earthquake was recorded by a total of fourteen accelerometers that operate in the city of Lima which show clearly the development of a complex process of rupture formed by two sources (R1 and R2) separated by 60-70 seconds. Maximum acceleration registered in the city of Lima was of 115.2 cm/seg² (0.12g) in the Urb. The Rinconada of the district the Molina located 155 km northwest from the epicenter. The periods associated to the maximum spectral acceleration appear to be between 0.1 to 0.4s in RIN and MOL, both located in the La Molina District; for ANC, CSM, MAY located in the Ancon, Rímac and Ate Vitarte district, are within the range of 0.1-0.6s; for CER, ANR, PUCP, CLD-CIP located in the San Borja, Santiago de Surco, San Miguel and San Isidro district the range is of 0.1-1.2s, and for CAL in Callao it is of 0.1-1.6s. The predominant periods have values close to 0.1s in the Molina and San Miguel distric, of 0.2s in Ate Vitarte and Rimac, of 0.3s in the Molina, Rimac, Ate Vitarte and Ancon, and of 0.5s in Santiago de Surco disctrict. In the Molina district, two acelerometric stations are located at less than 2 km away from each other, and present predominant periods next to 0.1s and 0.3s, which implies a strong variation of the physical properties of the ground at short distances. Shear wave velocity estimates, using the unidimensional method at stations MOL, MAY and ANC, give values of 80 m/s (with thicknesses less than 2 m), 200 m/s (with thicknesses less than 9 m) and of 690 m/s for the halfspace, values that suggest a compacted ground with respect to the rest of stations. Stations CAL and RIN show velocities of 60 of m/s (with thicknesses of 11 and 3 m respectively), a second layer of 140 m/s (with thicknesses of 12 and 7 m) over a halfspace of 450 m

Dynamic fracture network around faults: implications for earthquake ruptures, ground motion and energy budget

NASA Astrophysics Data System (ADS)

Okubo, K.; Bhat, H. S.; Rougier, E.; Lei, Z.; Knight, E. E.; Klinger, Y.

2017-12-01

Numerous studies have suggested that spontaneous earthquake ruptures can dynamically induce failure in secondary fracture network, regarded as damage zone around faults. The feedbacks of such fracture network play a crucial role in earthquake rupture, its radiated wave field and the total energy budget. A novel numerical modeling tool based on the combined finite-discrete element method (FDEM), which accounts for the main rupture propagation and nucleation/propagation of secondary cracks, was used to quantify the evolution of the fracture network and evaluate its effects on the main rupture and its associated radiation. The simulations were performed with the FDEM-based software tool, Hybrid Optimization Software Suite (HOSSedu) developed by Los Alamos National Laboratory. We first modeled an earthquake rupture on a planar strike-slip fault surrounded by a brittle medium where secondary cracks can be nucleated/activated by the earthquake rupture. We show that the secondary cracks are dynamically generated dominantly on the extensional side of the fault, mainly behind the rupture front, and it forms an intricate network of fractures in the damage zone. The rupture velocity thereby significantly decreases, by 10 to 20 percent, while the supershear transition length increases in comparison to the one with purely elastic medium. It is also observed that the high-frequency component (10 to 100 Hz) of the near-field ground acceleration is enhanced by the dynamically activated fracture network, consistent with field observations. We then conducted the case study in depth with various sets of initial stress state, and friction properties, to investigate the evolution of damage zone. We show that the width of damage zone decreases in depth, forming "flower-like" structure as the characteristic slip distance in linear slip-weakening law, or the fracture energy on the fault, is kept constant with depth. Finally, we compared the fracture energy on the fault to the energy

Correlation of ground motion and intensity for the 17 January 1994 Northridge, California, earthquake

USGS Publications Warehouse

Boatwright, J.; Thywissen, K.; Seekins, L.C.

2001-01-01

We analyze the correlations between intensity and a set of groundmotion parameters obtained from 66 free-field stations in Los Angeles County that recorded the 1994 Northridge earthquake. We use the tagging intensities from Thywissen and Boatwright (1998) because these intensities are determined independently on census tracts, rather than interpolated from zip codes, as are the modified Mercalli isoseismals from Dewey et al. (1995). The ground-motion parameters we consider are the peak ground acceleration (PGA), the peak ground velocity (PGV), the 5% damped pseudovelocity response spectral (PSV) ordinates at 14 periods from 0.1 to 7.5 sec, and the rms average of these spectral ordinates from 0.3 to 3 sec. Visual comparisons of the distribution of tagging intensity with contours of PGA, PGV, and the average PSV suggest that PGV and the average PSV are better correlated with the intensity than PGA. The correlation coefficients between the intensity and the ground-motion parameters bear this out: r = 0.75 for PGA, 0.85 for PGV, and 0.85 for the average PSV. Correlations between the intensity and the PSV ordinates, as a function of period, are strongest at 1.5 sec (r = 0.83) and weakest at 0.2 sec (r = 0.66). Regressing the intensity on the logarithms of these ground-motion parameters yields relations I ?? mlog?? with 3.0 ??? m ??? 5.2 for the parameters analyzed, where m = 4.4 ?? 0.7 for PGA, 3.4 ?? 0.4 for PGV, and 3.6 ?? 0.5 for the average PSV.

Ground Motion Prediction Equations Empowered by Stress Drop Measurement

NASA Astrophysics Data System (ADS)

Miyake, H.; Oth, A.

2015-12-01

Significant variation of stress drop is a crucial issue for ground motion prediction equations and probabilistic seismic hazard assessment, since only a few ground motion prediction equations take into account stress drop. In addition to average and sigma studies of stress drop and ground motion prediction equations (e.g., Cotton et al., 2013; Baltay and Hanks, 2014), we explore 1-to-1 relationship for each earthquake between stress drop and between-event residual of a ground motion prediction equation. We used the stress drop dataset of Oth (2013) for Japanese crustal earthquakes ranging 0.1 to 100 MPa and K-NET/KiK-net ground motion dataset against for several ground motion prediction equations with volcanic front treatment. Between-event residuals for ground accelerations and velocities are generally coincident with stress drop, as investigated by seismic intensity measures of Oth et al. (2015). Moreover, we found faster attenuation of ground acceleration and velocities for large stress drop events for the similar fault distance range and focal depth. It may suggest an alternative parameterization of stress drop to control attenuation distance rate for ground motion prediction equations. We also investigate 1-to-1 relationship and sigma for regional/national-scale stress drop variation and current national-scale ground motion equations.

Strong motions observed by K-NET and KiK-net during the 2016 Kumamoto earthquake sequence

NASA Astrophysics Data System (ADS)

Suzuki, Wataru; Aoi, Shin; Kunugi, Takashi; Kubo, Hisahiko; Morikawa, Nobuyuki; Nakamura, Hiromitsu; Kimura, Takeshi; Fujiwara, Hiroyuki

2017-01-01

The nationwide strong-motion seismograph network of K-NET and KiK-net in Japan successfully recorded the strong ground motions of the 2016 Kumamoto earthquake sequence, which show the several notable characteristics. For the first large earthquake with a JMA magnitude of 6.5 (21:26, April 14, 2016, JST), the large strong motions are concentrated near the epicenter and the strong-motion attenuations are well predicted by the empirical relation for crustal earthquakes with a moment magnitude of 6.1. For the largest earthquake of the sequence with a JMA magnitude of 7.3 (01:25, April 16, 2016, JST), the large peak ground accelerations and velocities extend from the epicentral area to the northeast direction. The attenuation feature of peak ground accelerations generally follows the empirical relation, whereas that for velocities deviates from the empirical relation for stations with the epicentral distance of greater than 200 km, which can be attributed to the large Love wave having a dominant period around 10 s. The large accelerations were observed at stations even in Oita region, more than 70 km northeast from the epicenter. They are attributed to the local induced earthquake in Oita region, whose moment magnitude is estimated to be 5.5 by matching the amplitudes of the corresponding phases with the empirical attenuation relation. The real-time strong-motion observation has a potential for contributing to the mitigation of the ongoing earthquake disasters. We test a methodology to forecast the regions to be exposed to the large shaking in real time, which has been developed based on the fact that the neighboring stations are already shaken, for the largest event of the Kumamoto earthquakes, and demonstrate that it is simple but effective to quickly make warning. We also shows that the interpolation of the strong motions in real time is feasible, which will be utilized for the real-time forecast of ground motions based on the observed shakings.[Figure not available

Rupture process and strong ground motions of the 2007 Niigataken Chuetsu-Oki earthquake -Directivity pulses striking the Kashiwazaki-Kariwa Nuclear Power Plant-

NASA Astrophysics Data System (ADS)

Irikura, K.; Kagawa, T.; Miyakoshi, K.; Kurahashi, S.

2007-12-01

The Niigataken Chuetsu-Oki earthquake occurred on July 16, 2007, northwest-off Kashiwazaki in Niigata Prefecture, Japan, causing severe damages of ten people dead, about 1300 injured, about 1000 collapsed houses and major lifelines suspended. In particular, strong ground motions from the earthquake struck the Kashiwazaki-Kariwa nuclear power plant (hereafter KKNPP), triggering a fire at an electric transformer and other problems such as leakage of water containing radioactive materials into air and the sea, although the radioactivity levels of the releases are as low as those of the radiation which normal citizens would receive from the natural environment in a year. The source mechanism of this earthquake is a reverse fault, but whether it is the NE-SW strike and NW dip or the SW-NE strike and SE dip are still controversial from the aftershock distribution and geological surveys near the source. Results of the rupture processes inverted by using the GPS and SAR data, tsunami data and teleseismic data so far did not succeed in determining which fault planes moved. Strong ground motions were recorded at about 390 stations by the K-NET of NIED including the stations very close to the source area. There was the KKNPP which is probably one of buildings and facilities closest to the source area. They have their own strong motion network with 22 three-components' accelerographs locating at ground-surface, underground, buildings and basements of reactors. The PGA attenuation-distance relationships made setting the fault plane estimated from the GPS data generally follow the empirical relations in Japan, for example, Fukushima and Tanaka (1990) and Si and Midorikawa (1999), even if either fault plane, SE dip or NW dip, is assumed. However, the strong ground motions in the site of the KKNPP had very large accelerations and velocities more than those expected from the empirical relations. The surface motions there had the PGA of more than 1200 gals and even underground

Toward Exascale Earthquake Ground Motion Simulations for Near-Fault Engineering Analysis

DOE PAGES

Johansen, Hans; Rodgers, Arthur; Petersson, N. Anders; ...

2017-09-01

Modernizing SW4 for massively parallel time-domain simulations of earthquake ground motions in 3D earth models increases resolution and provides ground motion estimates for critical infrastructure risk evaluations. Simulations of ground motions from large (M ≥ 7.0) earthquakes require domains on the order of 100 to500 km and spatial granularity on the order of 1 to5 m resulting in hundreds of billions of grid points. Surface-focused structured mesh refinement (SMR) allows for more constant grid point per wavelength scaling in typical Earth models, where wavespeeds increase with depth. In fact, MR allows for simulations to double the frequency content relative tomore » a fixed grid calculation on a given resource. The authors report improvements to the SW4 algorithm developed while porting the code to the Cori Phase 2 (Intel Xeon Phi) systems at the National Energy Research Scientific Computing Center (NERSC) at Lawrence Berkeley National Laboratory. As a result, investigations of the performance of the innermost loop of the calculations found that reorganizing the order of operations can improve performance for massive problems.« less

Toward Exascale Earthquake Ground Motion Simulations for Near-Fault Engineering Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johansen, Hans; Rodgers, Arthur; Petersson, N. Anders

Modernizing SW4 for massively parallel time-domain simulations of earthquake ground motions in 3D earth models increases resolution and provides ground motion estimates for critical infrastructure risk evaluations. Simulations of ground motions from large (M ≥ 7.0) earthquakes require domains on the order of 100 to500 km and spatial granularity on the order of 1 to5 m resulting in hundreds of billions of grid points. Surface-focused structured mesh refinement (SMR) allows for more constant grid point per wavelength scaling in typical Earth models, where wavespeeds increase with depth. In fact, MR allows for simulations to double the frequency content relative tomore » a fixed grid calculation on a given resource. The authors report improvements to the SW4 algorithm developed while porting the code to the Cori Phase 2 (Intel Xeon Phi) systems at the National Energy Research Scientific Computing Center (NERSC) at Lawrence Berkeley National Laboratory. As a result, investigations of the performance of the innermost loop of the calculations found that reorganizing the order of operations can improve performance for massive problems.« less

3-D velocity structure model for long-period ground motion simulation of the hypothetical Nankai Earthquake

NASA Astrophysics Data System (ADS)

Kagawa, T.; Petukhin, A.; Koketsu, K.; Miyake, H.; Murotani, S.; Tsurugi, M.

2010-12-01

Three dimensional velocity structure model of southwest Japan is provided to simulate long-period ground motions due to the hypothetical subduction earthquakes. The model is constructed from numerous physical explorations conducted in land and offshore areas and observational study of natural earthquakes. Any available information is involved to explain crustal structure and sedimentary structure. Figure 1 shows an example of cross section with P wave velocities. The model has been revised through numbers of simulations of small to middle earthquakes as to have good agreement with observed arrival times, amplitudes, and also waveforms including surface waves. Figure 2 shows a comparison between Observed (dash line) and simulated (solid line) waveforms. Low velocity layers have added on seismological basement to reproduce observed records. The thickness of the layer has been adjusted through iterative analysis. The final result is found to have good agreement with the results from other physical explorations; e.g. gravity anomaly. We are planning to make long-period (about 2 to 10 sec or longer) simulations of ground motion due to the hypothetical Nankai Earthquake with the 3-D velocity structure model. As the first step, we will simulate the observed ground motions of the latest event occurred in 1946 to check the source model and newly developed velocity structure model. This project is partly supported by Integrated Research Project for Long-Period Ground Motion Hazard Maps by Ministry of Education, Culture, Sports, Science and Technology (MEXT). The ground motion data used in this study were provided by National Research Institute for Earth Science and Disaster Prevention Disaster (NIED). Figure 1 An example of cross section with P wave velocities Figure 2 Observed (dash line) and simulated (solid line) waveforms due to a small earthquake

Strong motion observations and recordings from the great Wenchuan Earthquake

USGS Publications Warehouse

Li, X.; Zhou, Z.; Yu, H.; Wen, R.; Lu, D.; Huang, M.; Zhou, Y.; Cu, J.

2008-01-01

The National Strong Motion Observation Network System (NSMONS) of China is briefly introduced in this paper. The NSMONS consists of permanent free-field stations, special observation arrays, mobile observatories and a network management system. During the Wenchuan Earthquake, over 1,400 components of acceleration records were obtained from 460 permanent free-field stations and three arrays for topographical effect and structural response observation in the network system from the main shock, and over 20,000 components of acceleration records from strong aftershocks occurred before August 1, 2008 were also obtained by permanent free-field stations of the NSMONS and 59 mobile instruments quickly deployed after the main shock. The strong motion recordings from the main shock and strong aftershocks are summarized in this paper. In the ground motion recordings, there are over 560 components with peak ground acceleration (PGA) over 10 Gal, the largest being 957.7 Gal. The largest PGA recorded during the aftershock exceeds 300 Gal. ?? 2008 Institute of Engineering Mechanics, China Earthquake Administration and Springer-Verlag GmbH.

Estimated cause of extreme acceleration records at the KiK-net IWTH25 station during the 2008 Iwate-Miyagi Nairiku earthquake, Japan

NASA Astrophysics Data System (ADS)

Ohmachi, Tatsuo; Inoue, Shusaku; Mizuno, Ken-Ichi; Yamada, Masato

During the 2008 Iwate-Miyagi Nairiku earthquake in Japan (MJ =7.2), extremely high accelerations were recorded at the KiK-net IWTH25 (Ichinoseki-nishi) station. The peak acceleration in the vertical component of the surface record was about 4 g where g is acceleration due to gravity, and the upward acceleration in the surface record was much larger than the downward acceleration. Some researchers have suggested that the ground surface was tossed into the air like a body on a trampoline. However, additional features found in the surface record suggest rocking motion accompanied with downward impact of the station with the ground. For example, there are many vertical peaks that can be found to occur at the same time as the horizontal peaks. After obtaining information about the station, in-situ investigations, shake-table experiments, and numerical simulations were conducted to determine the fundamental characteristics of the rocking motion and to reproduce the acceleration time histories of the surface record by using the bore-hole record at a depth of 260 m as the input motion. Prior to the numerical simulation, the wave velocities of subsurface layers were evaluated from Fourier spectra of both records, which showed that the velocities were reduced considerably during the main shock. A 2-D FEM code capable of handling separation and impact between the elements was used for the numerical simulation. Simulation results are shown in Figs. 17 and 18 indicating the impact between the IWTH25 station and the ground at around 4 sec when the acceleration in the vertical direction was about 4 g. Three kinds of acceleration time histories are shown with fairly good agreement between the simulated and observed time histories, suggesting the influence of the station is included in the record. It is also indicated that the vertical acceleration at the free surface without the influence of the IWTH25 station is about 1.6 g.

A short note on ground-motion recordings from the M 7.9 Wenchuan, China, earthquake and ground-motion prediction equations in the Central and Eastern United States

USGS Publications Warehouse

Wang, Z.; Lu, M.

2011-01-01

The 12 May 2008 Wenchuan earthquake (M 7.9) occurred along the western edge of the eastern China SCR and was well recorded by modern strong-motion instruments: 93 strong-motion stations within 1.4 to 300 km rupture distance recorded the main event. Preliminary comparisons show some similarities between ground-motion attenuation in the Wenchuan region and the central and eastern United States, suggesting that ground motions from the Wenchuan earthquake could be used as a database providing constraints for developing GMPEs for large earthquakes in the central and eastern United States.

Sensitivity analysis of tall buildings in Semarang, Indonesia due to fault earthquakes with maximum 7 Mw

NASA Astrophysics Data System (ADS)

Partono, Windu; Pardoyo, Bambang; Atmanto, Indrastono Dwi; Azizah, Lisa; Chintami, Rouli Dian

2017-11-01

Fault is one of the dangerous earthquake sources that can cause building failure. A lot of buildings were collapsed caused by Yogyakarta (2006) and Pidie (2016) fault source earthquakes with maximum magnitude 6.4 Mw. Following the research conducted by Team for Revision of Seismic Hazard Maps of Indonesia 2010 and 2016, Lasem, Demak and Semarang faults are three closest earthquake sources surrounding Semarang. The ground motion from those three earthquake sources should be taken into account for structural design and evaluation. Most of tall buildings, with minimum 40 meter high, in Semarang were designed and constructed following the 2002 and 2012 Indonesian Seismic Code. This paper presents the result of sensitivity analysis research with emphasis on the prediction of deformation and inter-story drift of existing tall building within the city against fault earthquakes. The analysis was performed by conducting dynamic structural analysis of 8 (eight) tall buildings using modified acceleration time histories. The modified acceleration time histories were calculated for three fault earthquakes with magnitude from 6 Mw to 7 Mw. The modified acceleration time histories were implemented due to inadequate time histories data caused by those three fault earthquakes. Sensitivity analysis of building against earthquake can be predicted by evaluating surface response spectra calculated using seismic code and surface response spectra calculated from acceleration time histories from a specific earthquake event. If surface response spectra calculated using seismic code is greater than surface response spectra calculated from acceleration time histories the structure will stable enough to resist the earthquake force.

Understanding earthquake hazards in urban areas - Evansville Area Earthquake Hazards Mapping Project

USGS Publications Warehouse

Boyd, Oliver S.

2012-01-01

The region surrounding Evansville, Indiana, has experienced minor damage from earthquakes several times in the past 200 years. Because of this history and the proximity of Evansville to the Wabash Valley and New Madrid seismic zones, there is concern among nearby communities about hazards from earthquakes. Earthquakes currently cannot be predicted, but scientists can estimate how strongly the ground is likely to shake as a result of an earthquake and are able to design structures to withstand this estimated ground shaking. Earthquake-hazard maps provide one way of conveying such information and can help the region of Evansville prepare for future earthquakes and reduce earthquake-caused loss of life and financial and structural loss. The Evansville Area Earthquake Hazards Mapping Project (EAEHMP) has produced three types of hazard maps for the Evansville area: (1) probabilistic seismic-hazard maps show the ground motion that is expected to be exceeded with a given probability within a given period of time; (2) scenario ground-shaking maps show the expected shaking from two specific scenario earthquakes; (3) liquefaction-potential maps show how likely the strong ground shaking from the scenario earthquakes is to produce liquefaction. These maps complement the U.S. Geological Survey's National Seismic Hazard Maps but are more detailed regionally and take into account surficial geology, soil thickness, and soil stiffness; these elements greatly affect ground shaking.

Near-Fault Ground Motion Velocity Pulses Input and Its Non-Stationary Characteristics from 2015 Gorkha Nepal Mw7.8 Earthquake KATNP Station

NASA Astrophysics Data System (ADS)

Chen, Bo; Wen, Zengping; Wang, Fang

2017-04-01

Using near-fault strong motions from Nepal Mw7.8 earthquake at KATNP station in the city center of Kathmandu, velocity-pulse and non-stationary characteristics of the strong motions are shown, and the reason and potential effect on earthquake damage for intense non-stationary characteristics of near fault velocity-pulse strong motions are mainly studied. The observed strong ground motions of main shock were collected from KATNP station located in 76 kilometers south-east away from epicenter along with forward direction of the rupture fault at an inter-montane basin of the Himalaya. Large velocity pulse show the period of velocity pulse reach up to 6.6s and peak ground velocity of the pulse ground motion is 120 cm/s. Compared with the median spectral acceleration value of NGA prediction equation, significant long-period amplification effect due to velocity pulse is detected at period more than 3.2s. Wavelet analysis shows that the two horizontal component of ground motion is intensely concentration of energy in a short time range of 25-38s and period range of 4-8s. The maximum wavelet-coefficient of horizontal component is 2455, which is about four time of vertical component of strong ground motion. On the perspective of this study, large velocity pulses are identified from two orthogonal components using wavelet method. Intense non-stationary characteristics amplitude and frequency content are mainly caused by site conditions and fault rupture mechanism, which will help to understand the damage evaluation and serve local seismic design.

Strong ground motion inferred from liquefaction caused by the 1811-1812 New Madrid, Missouri, earthquakes

USGS Publications Warehouse

Holzer, Thomas L.; Noce, Thomas E.; Bennett, Michael J.

2015-01-01

Peak ground accelerations (PGAs) in the epicentral region of the 1811–1812 New Madrid, Missouri, earthquakes are inferred from liquefaction to have been no greater than ∼0.35g. PGA is inferred in an 11,380  km2 area in the Lower Mississippi Valley in Arkansas and Missouri where liquefaction was extensive in 1811–1812. PGA was inferred by applying liquefaction probability curves, which were originally developed for liquefaction hazard mapping, to detailed maps of liquefaction by Obermeier (1989). The low PGA is inferred because both a shallow (1.5 m deep) water table and a large moment magnitude (M 7.7) earthquake were assumed in the analysis. If a deep (5.0 m) water table and a small magnitude (M 6.8) earthquake are assumed, the maximum inferred PGA is 1.10g. Both inferred PGA values are based on an assumed and poorly constrained correction for sand aging. If an aging correction is not assumed, then the inferred PGA is no greater than 0.22g. A low PGA value may be explained by nonlinear site response. Soils in the study area have an averageVS30 of 220±15  m/s. A low inferred PGA is consistent with PGA values estimated from ground‐motion prediction equations that have been proposed for the New Madrid seismic zone when these estimates are corrected for nonlinear soil site effects. This application of liquefaction probability curves demonstrates their potential usefulness in paleoseismology.

Prediction of spectral acceleration response ordinates based on PGA attenuation

USGS Publications Warehouse

Graizer, V.; Kalkan, E.

2009-01-01

Developed herein is a new peak ground acceleration (PGA)-based predictive model for 5% damped pseudospectral acceleration (SA) ordinates of free-field horizontal component of ground motion from shallow-crustal earthquakes. The predictive model of ground motion spectral shape (i.e., normalized spectrum) is generated as a continuous function of few parameters. The proposed model eliminates the classical exhausted matrix of estimator coefficients, and provides significant ease in its implementation. It is structured on the Next Generation Attenuation (NGA) database with a number of additions from recent Californian events including 2003 San Simeon and 2004 Parkfield earthquakes. A unique feature of the model is its new functional form explicitly integrating PGA as a scaling factor. The spectral shape model is parameterized within an approximation function using moment magnitude, closest distance to the fault (fault distance) and VS30 (average shear-wave velocity in the upper 30 m) as independent variables. Mean values of its estimator coefficients were computed by fitting an approximation function to spectral shape of each record using robust nonlinear optimization. Proposed spectral shape model is independent of the PGA attenuation, allowing utilization of various PGA attenuation relations to estimate the response spectrum of earthquake recordings.

Influence of surface-normal ground acceleration on the initiation of the Jih-Feng-Erh-Shan landslide during the 1999 Chi-Chi, Taiwan, earthquake

USGS Publications Warehouse

Huang, C.-C.; Lee, Y.-H.; Liu, Huaibao P.; Keefer, D.K.; Jibson, R.W.

2001-01-01

The 1999 Chi-Chi, Taiwan, earthquake triggered numerous landslides throughout a large area in the Central Range, to the east, southeast, and south of the fault rupture. Among them are two large rock avalanches, at Tsaoling and at Jih-Feng-Erh-Shan. At Jih-Feng-Erh-Shan, the entire thickness (30-50 m) of the Miocene Changhukeng Shale over an area of 1 km2 slid down its bedding plane for a distance of about 1 km. Initial movement of the landslide was nearly purely translational. We investigate the effect of surface-normal acceleration on the initiation of the Jih-Feng-Erh-Shan landslide using a block slide model. We show that this acceleration, currently not considered by dynamic slope-stability analysis methods, significantly influences the initiation of the landslide.

ON NONSTATIONARY STOCHASTIC MODELS FOR EARTHQUAKES.

USGS Publications Warehouse

Safak, Erdal; Boore, David M.

1986-01-01

A seismological stochastic model for earthquake ground-motion description is presented. Seismological models are based on the physical properties of the source and the medium and have significant advantages over the widely used empirical models. The model discussed here provides a convenient form for estimating structural response by using random vibration theory. A commonly used random process for ground acceleration, filtered white-noise multiplied by an envelope function, introduces some errors in response calculations for structures whose periods are longer than the faulting duration. An alternate random process, filtered shot-noise process, eliminates these errors.

The deadly Morelos-Puebla, Mexico Intraslab Earthquake of 19 September 2017 (Mw7.1): Was the Earthquake Unexpected and Were the Ground Motions and Damage Pattern in Mexico City Abnormal?

NASA Astrophysics Data System (ADS)

Perez-Campos, X.; Singh, S. K.; Arroyo, D.; Cruz-Atienza, V. M.; Ordaz, M.; Hjorleifsdottir, V.; Iglesias, A.

2017-12-01

On 19 September 2017, thirty two years after the 1985 Michoacan interplate earthquake (Mw8.0), the city was once again devastated but this time by a Mw7.1 intraslab earthquake. The 2017 earthquake was located near the border of the states of Morelos and Puebla (18.410N, -98.710E; H=57 km), to SSE of Mexico City, at a hypocentral distance of about 127 km. It caused great panic in Mexico City, collapse of 44 buildings, and severely damaged many others. More than 200 persons were killed in the city. It was the second most destructive earthquake in the history of Mexico City, next only to the 1985 earthquake. A strong-motion station at CU located on basalt lava flows on main campus UNAM has been in continuous operation since 1964. PGA of 59 gal at CU during the 2017 earthquake is the largest ever, two times greater than that recorded during the 1985 earthquake (29 gal). The 2017 earthquake raised questions that are critical in fathoming the seismic vulnerability of the city and in its reconstruction. Was such an intraslab earthquake (Mw 7 at a hypocentral distance of 127 km) unexpected? Were the recorded ground motions in the city unusually high for such an earthquake? Why did the damage pattern during the earthquake differ from that observed during the 1985 earthquake? The earthquake was the closest M>5 intraslab earthquake to Mexico City ever recorded. However, Mw 5.9 events have occurred in recent years in the vicinity of the 2017 earthquake (R 145 km). Three Mw≥6.9 earthquakes have occurred since 1964 in the distance range 184-225 km. Thus, Mw and R of the earthquake was not surprising. However, a comparison of Fourier acceleration spectra at CU of 10 intraslab earthquakes with largest PGA, reduced to a common distance of R=127 km, shows that the amplitudes of the 2017 events were abnormally high in 1-2s range. Spectra of intraslab events at CU are enriched at higher frequencies relative to interplate ones because of closer distance, greater depth and higher

Statistical analysis of low-rise building damage caused by the San Fernando earthquake

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scholl, R.E.

1974-02-01

An empirical investigation of damage to low-rise buildings in two selected control areas within Glendale, California, caused by the ground motion precipitated by the San Fernando earthquake of February 9, 1971 is summarized. The procedures for obtaining the appropriate data and the methodology used in deriving ground motion-damage relationships are described. Motion-damage relationships are derived for overall damage and for the most frequently damaged building components. Overall motion-damage relationships are expressed in terms of damage incidence (damage ratio) and damage cost (damage cost factor). The motion-damage relationships derived from the earthquake data are compared with similar data obtained for lou-risemore » buildings subjected to ground motion generated by an underground nuclear explosion. Overall comparison results show that for the same spectral acceleration, the earthquake caused slightly more damage. Differences in ground-motion characteristics for the two types of disturbances provide the most probable explanation for this discrepancy. (auth)« less

Slip pulse and resonance of the Kathmandu basin during the 2015 Gorkha earthquake, Nepal

NASA Astrophysics Data System (ADS)

Galetzka, J.; Melgar, D.; Genrich, J. F.; Geng, J.; Owen, S.; Lindsey, E. O.; Xu, X.; Bock, Y.; Avouac, J.-P.; Adhikari, L. B.; Upreti, B. N.; Pratt-Sitaula, B.; Bhattarai, T. N.; Sitaula, B. P.; Moore, A.; Hudnut, K. W.; Szeliga, W.; Normandeau, J.; Fend, M.; Flouzat, M.; Bollinger, L.; Shrestha, P.; Koirala, B.; Gautam, U.; Bhatterai, M.; Gupta, R.; Kandel, T.; Timsina, C.; Sapkota, S. N.; Rajaure, S.; Maharjan, N.

2015-09-01

Detailed geodetic imaging of earthquake ruptures enhances our understanding of earthquake physics and associated ground shaking. The 25 April 2015 moment magnitude 7.8 earthquake in Gorkha, Nepal was the first large continental megathrust rupture to have occurred beneath a high-rate (5-hertz) Global Positioning System (GPS) network. We used GPS and interferometric synthetic aperture radar data to model the earthquake rupture as a slip pulse ~20 kilometers in width, ~6 seconds in duration, and with a peak sliding velocity of 1.1 meters per second, which propagated toward the Kathmandu basin at ~3.3 kilometers per second over ~140 kilometers. The smooth slip onset, indicating a large (~5-meter) slip-weakening distance, caused moderate ground shaking at high frequencies (>1 hertz; peak ground acceleration, ~16% of Earth’s gravity) and minimized damage to vernacular dwellings. Whole-basin resonance at a period of 4 to 5 seconds caused the collapse of tall structures, including cultural artifacts.

Slip pulse and resonance of the Kathmandu basin during the 2015 Gorkha earthquake, Nepal.

PubMed

Galetzka, J; Melgar, D; Genrich, J F; Geng, J; Owen, S; Lindsey, E O; Xu, X; Bock, Y; Avouac, J-P; Adhikari, L B; Upreti, B N; Pratt-Sitaula, B; Bhattarai, T N; Sitaula, B P; Moore, A; Hudnut, K W; Szeliga, W; Normandeau, J; Fend, M; Flouzat, M; Bollinger, L; Shrestha, P; Koirala, B; Gautam, U; Bhatterai, M; Gupta, R; Kandel, T; Timsina, C; Sapkota, S N; Rajaure, S; Maharjan, N

2015-09-04

Detailed geodetic imaging of earthquake ruptures enhances our understanding of earthquake physics and associated ground shaking. The 25 April 2015 moment magnitude 7.8 earthquake in Gorkha, Nepal was the first large continental megathrust rupture to have occurred beneath a high-rate (5-hertz) Global Positioning System (GPS) network. We used GPS and interferometric synthetic aperture radar data to model the earthquake rupture as a slip pulse ~20 kilometers in width, ~6 seconds in duration, and with a peak sliding velocity of 1.1 meters per second, which propagated toward the Kathmandu basin at ~3.3 kilometers per second over ~140 kilometers. The smooth slip onset, indicating a large (~5-meter) slip-weakening distance, caused moderate ground shaking at high frequencies (>1 hertz; peak ground acceleration, ~16% of Earth's gravity) and minimized damage to vernacular dwellings. Whole-basin resonance at a period of 4 to 5 seconds caused the collapse of tall structures, including cultural artifacts. Copyright © 2015, American Association for the Advancement of Science.

Estimation of ground motion for Bhuj (26 January 2001; Mw 7.6 and for future earthquakes in India

USGS Publications Warehouse

Singh, S.K.; Bansal, B.K.; Bhattacharya, S.N.; Pacheco, J.F.; Dattatrayam, R.S.; Ordaz, M.; Suresh, G.; ,; Hough, S.E.

2003-01-01

Only five moderate and large earthquakes (Mw ???5.7) in India-three in the Indian shield region and two in the Himalayan arc region-have given rise to multiple strong ground-motion recordings. Near-source data are available for only two of these events. The Bhuj earthquake (Mw 7.6), which occurred in the shield region, gave rise to useful recordings at distances exceeding 550 km. Because of the scarcity of the data, we use the stochastic method to estimate ground motions. We assume that (1) S waves dominate at R < 100 km and Lg waves at R ??? 100 km, (2) Q = 508f0.48 is valid for the Indian shield as well as the Himalayan arc region, (3) the effective duration is given by fc-1 + 0.05R, where fc is the corner frequency, and R is the hypocentral distance in kilometer, and (4) the acceleration spectra are sharply cut off beyond 35 Hz. We use two finite-source stochastic models. One is an approximate model that reduces to the ??2-source model at distances greater that about twice the source dimension. This model has the advantage that the ground motion is controlled by the familiar stress parameter, ????. In the other finite-source model, which is more reliable for near-source ground-motion estimation, the high-frequency radiation is controlled by the strength factor, sfact, a quantity that is physically related to the maximum slip rate on the fault. We estimate ???? needed to fit the observed Amax and Vmax data of each earthquake (which are mostly in the far field). The corresponding sfact is obtained by requiring that the predicted curves from the two models match each other in the far field up to a distance of about 500 km. The results show: (1) The ???? that explains Amax data for shield events may be a function of depth, increasing from ???50 bars at 10 km to ???400 bars at 36 km. The corresponding sfact values range from 1.0-2.0. The ???? values for the two Himalayan arc events are 75 and 150 bars (sfact = 1.0 and 1.4). (2) The ???? required to explain Vmax data

Strong ground motion in the Taipei basin from the 1999 Chi-Chi, Taiwan, earthquake

USGS Publications Warehouse

Fletcher, Joe B.; Wen, K.-L.

2005-01-01

The Taipei basin, located in northwest Taiwan about 160 km from the epicenter of the Chi-Chi earthquake, is a shallow, triangular-shaped basin filled with low-velocity fluvial deposits. There is a strong velocity contrast across the basement interface of about 600 m/sec at a depth of about 600-700 m in the deeper section of the basin, suggesting that ground motion should be amplified at sites in the basin. In this article, the ground-motion recordings are analyzed to determine the effect of the basin both in terms of amplifications expected from a 1D model of the sediments in the basin and in terms of the 3D structure of the basin. Residuals determined for peak acceleration from attenuation curves are more positive (amplified) in the basin (average of 5.3 cm/ sec2 compared to - 24.2 cm/sec2 for those stations outside the basin and between 75 and 110 km from the surface projection of the faulted area, a 40% increase in peak ground acceleration). Residuals for peak velocity are also significantly more positive at stations in the basin (31.8 cm/sec compared to 20.0 cm/sec out). The correlation of peak motion with depth to basement, while minor in peak acceleration, is stronger in the peak velocities. Record sections of ground motion from stations in and around the Taipei basin show that the largest long-period arrival, which is coherent across the region, is strongest on the vertical component and has a period of about 10-12 sec. This phase appears to be a Rayleigh wave, probably associated with rupture at the north end of the Chelungpu fault. Records of strong motion from stations in and near the basin have an additional, higher frequency signal: nearest the deepest point in the basin, the signal is characterized by frequencies of about 0.3 - 0.4 Hz. These frequencies are close to simple predictions using horizontal layers and the velocity structure of the basin. Polarizations of the S wave are mostly coherent across the array, although there are significant

A stochastic estimate of ground motion at Oceano, California, for the M 6.5 22 December 2003 San Simeon earthquake, derived from aftershock recordings

USGS Publications Warehouse

Di, Alessandro C.; Boatwright, J.

2006-01-01

The U.S. Geological Survey deployed a digital seismic station in Oceano, California, in February 2004, to investigate the cause of damage and liquefaction from the 22 December 2003 M 6.5 San Simeon earthquake. This station recorded 11 M > 2.8 aftershocks in almost 8 weeks. We analyze these recordings, together with recordings of the mainshock and the same aftershocks obtained from nearby stations in Park Hill and San Luis Obispo, to estimate the mainshock ground motion in Oceano. We estimate the Fourier amplitude spectrum using generalized spectral ratio analysis. We test a set of aftershocks as Green's functions by comparing simulated and recorded acceleration amplitude spectra for the mainshock at San Luis Obispo and Park Hill. We convolve the aftershock accelerograms with a stochastic operator to simulate the duration and phase of the mainshock accelerograms. This approximation allows us to extend the range of aftershocks that can be used as Green's functions to events nearly three magnitude units smaller than the mainshock. Our realizations for the mainshock accelerogram at Oceano yield peak ground accelerations distributed as 28% ?? 4%g. We interpret these realizations as upper bounds for the actual ground motion, because our analysis assumes a linear response, whereas the presence of liquefaction indicates that the ground behaved nonlinearly in Oceano.

Probabilistic Seismic Hazard Assessment for Himalayan-Tibetan Region from Historical and Instrumental Earthquake Catalogs

NASA Astrophysics Data System (ADS)

Rahman, M. Moklesur; Bai, Ling; Khan, Nangyal Ghani; Li, Guohui

2018-02-01

The Himalayan-Tibetan region has a long history of devastating earthquakes with wide-spread casualties and socio-economic damages. Here, we conduct the probabilistic seismic hazard analysis by incorporating the incomplete historical earthquake records along with the instrumental earthquake catalogs for the Himalayan-Tibetan region. Historical earthquake records back to more than 1000 years ago and an updated, homogenized and declustered instrumental earthquake catalog since 1906 are utilized. The essential seismicity parameters, namely, the mean seismicity rate γ, the Gutenberg-Richter b value, and the maximum expected magnitude M max are estimated using the maximum likelihood algorithm assuming the incompleteness of the catalog. To compute the hazard value, three seismogenic source models (smoothed gridded, linear, and areal sources) and two sets of ground motion prediction equations are combined by means of a logic tree on accounting the epistemic uncertainties. The peak ground acceleration (PGA) and spectral acceleration (SA) at 0.2 and 1.0 s are predicted for 2 and 10% probabilities of exceedance over 50 years assuming bedrock condition. The resulting PGA and SA maps show a significant spatio-temporal variation in the hazard values. In general, hazard value is found to be much higher than the previous studies for regions, where great earthquakes have actually occurred. The use of the historical and instrumental earthquake catalogs in combination of multiple seismogenic source models provides better seismic hazard constraints for the Himalayan-Tibetan region.

Stochastic modelling of a large subduction interface earthquake in Wellington, New Zealand

NASA Astrophysics Data System (ADS)

Francois-Holden, C.; Zhao, J.

2012-12-01

The Wellington region, home of New Zealand's capital city, is cut by a number of major right-lateral strike slip faults, and is underlain by the currently locked west-dipping subduction interface between the down going Pacific Plate, and the over-riding Australian Plate. A potential cause of significant earthquake loss in the Wellington region is a large magnitude (perhaps 8+) "subduction earthquake" on the Australia-Pacific plate interface, which lies ~23 km beneath Wellington City. "It's Our Fault" is a project involving a comprehensive study of Wellington's earthquake risk. Its objective is to position Wellington city to become more resilient, through an encompassing study of the likelihood of large earthquakes, and the effects and impacts of these earthquakes on humans and the built environment. As part of the "It's Our Fault" project, we are working on estimating ground motions from potential large plate boundary earthquakes. We present the latest results on ground motion simulations in terms of response spectra and acceleration time histories. First we characterise the potential interface rupture area based on previous geodetically-derived estimates interface of slip deficit. Then, we entertain a suitable range of source parameters, including various rupture areas, moment magnitudes, stress drops, slip distributions and rupture propagation directions. Our comprehensive study also includes simulations from historical large world subduction events translated into the New Zealand subduction context, such as the 2003 M8.3 Tokachi-Oki Japan earthquake and the M8.8 2010 Chili earthquake. To model synthetic seismograms and the corresponding response spectra we employed the EXSIM code developed by Atkinson et al. (2009), with a regional attenuation model based on the 3D attenuation model for the lower North-Island which has been developed by Eberhart-Phillips et al. (2005). The resulting rupture scenarios all produce long duration shaking, and peak ground

The HayWired Earthquake Scenario—Earthquake Hazards

USGS Publications Warehouse

Detweiler, Shane T.; Wein, Anne M.

2017-04-24

The HayWired scenario is a hypothetical earthquake sequence that is being used to better understand hazards for the San Francisco Bay region during and after an earthquake of magnitude 7 on the Hayward Fault. The 2014 Working Group on California Earthquake Probabilities calculated that there is a 33-percent likelihood of a large (magnitude 6.7 or greater) earthquake occurring on the Hayward Fault within three decades. A large Hayward Fault earthquake will produce strong ground shaking, permanent displacement of the Earth’s surface, landslides, liquefaction (soils becoming liquid-like during shaking), and subsequent fault slip, known as afterslip, and earthquakes, known as aftershocks. The most recent large earthquake on the Hayward Fault occurred on October 21, 1868, and it ruptured the southern part of the fault. The 1868 magnitude-6.8 earthquake occurred when the San Francisco Bay region had far fewer people, buildings, and infrastructure (roads, communication lines, and utilities) than it does today, yet the strong ground shaking from the earthquake still caused significant building damage and loss of life. The next large Hayward Fault earthquake is anticipated to affect thousands of structures and disrupt the lives of millions of people. Earthquake risk in the San Francisco Bay region has been greatly reduced as a result of previous concerted efforts; for example, tens of billions of dollars of investment in strengthening infrastructure was motivated in large part by the 1989 magnitude 6.9 Loma Prieta earthquake. To build on efforts to reduce earthquake risk in the San Francisco Bay region, the HayWired earthquake scenario comprehensively examines the earthquake hazards to help provide the crucial scientific information that the San Francisco Bay region can use to prepare for the next large earthquake, The HayWired Earthquake Scenario—Earthquake Hazards volume describes the strong ground shaking modeled in the scenario and the hazardous movements of

Relation of landslides triggered by the Kiholo Bay earthquake to modeled ground motion

USGS Publications Warehouse

Harp, Edwin L.; Hartzell, Stephen H.; Jibson, Randall W.; Ramirez-Guzman, L.; Schmitt, Robert G.

2014-01-01

The 2006 Kiholo Bay, Hawaii, earthquake triggered high concentrations of rock falls and slides in the steep canyons of the Kohala Mountains along the north coast of Hawaii. Within these mountains and canyons a complex distribution of landslides was triggered by the earthquake shaking. In parts of the area, landslides were preferentially located on east‐facing slopes, whereas in other parts of the canyons no systematic pattern prevailed with respect to slope aspect or vertical position on the slopes. The geology within the canyons is homogeneous, so we hypothesize that the variable landslide distribution is the result of localized variation in ground shaking; therefore, we used a state‐of‐the‐art, high‐resolution ground‐motion simulation model to see if it could reproduce the landslide‐distribution patterns. We used a 3D finite‐element analysis to model earthquake shaking using a 10 m digital elevation model and slip on a finite‐fault model constructed from teleseismic records of the mainshock. Ground velocity time histories were calculated up to a frequency of 5 Hz. Dynamic shear strain also was calculated and compared with the landslide distribution. Results were mixed for the velocity simulations, with some areas showing correlation of landslide locations with peak modeled ground motions but many other areas showing no such correlation. Results were much improved for the comparison with dynamic shear strain. This suggests that (1) rock falls and slides are possibly triggered by higher frequency ground motions (velocities) than those in our simulations, (2) the ground‐motion velocity model needs more refinement, or (3) dynamic shear strain may be a more fundamental measurement of the decoupling process of slope materials during seismic shaking.

Scenario earthquake hazards for the Long Valley Caldera-Mono Lake area, east-central California (ver. 2.0, January 2018)

USGS Publications Warehouse

Chen, Rui; Branum, David M.; Wills, Chris J.; Hill, David P.

2014-06-30

to the NSHM scenario were developed for the Hilton Creek and Hartley Springs Faults to account for different opinions in how far these two faults extend into Long Valley Caldera. For each scenario, ground motions were calculated using the current standard practice: the deterministic seismic hazard analysis program developed by Art Frankel of USGS and three Next Generation Ground Motion Attenuation (NGA) models. Ground motion calculations incorporated the potential amplification of seismic shaking by near-surface soils defined by a map of the average shear wave velocity in the uppermost 30 m (VS30) developed by CGS.In addition to ground shaking and shaking-related ground failure such as liquefaction and earthquake induced landslides, earthquakes cause surface rupture displacement, which can lead to severe damage of buildings and lifelines. For each earthquake scenario, potential surface fault displacements are estimated using deterministic and probabilistic approaches. Liquefaction occurs when saturated sediments lose their strength because of ground shaking. Zones of potential liquefaction are mapped by incorporating areas where loose sandy sediments, shallow groundwater, and strong earthquake shaking coincide in the earthquake scenario. The process for defining zones of potential landslide and rockfall incorporates rock strength, surface slope, and existing landslides, with ground motions caused by the scenario earthquake.Each scenario is illustrated with maps of seismic shaking potential and fault displacement, liquefaction, and landslide potential. Seismic shaking is depicted by the distribution of shaking intensity, peak ground acceleration, and 1.0-second spectral acceleration. One-second spectral acceleration correlates well with structural damage to surface facilities. Acceleration greater than 0.2 g is often associated with strong ground shaking and may cause moderate to heavy damage. The extent of strong shaking is influenced by subsurface fault dip and near

Low-Frequency Amplitudes Observed in a Set of the Strongest Recorded Ground Motions (Invited)

NASA Astrophysics Data System (ADS)

Anderson, J. G.; Koketsu, K.; Miyake, H.

2010-12-01

Anderson (2010) compiled a set of “exceptional” ground motion characterized by peak acceleration that exceeds 500 gal on at least one component or peak velocity that exceeds 50 cm/s on at least one component. With the addition of more recent data, there are now over 280 openly available records that meet these criteria. These data are examined to find to the empirical upper bound of observed pseudo-acceleration (PSA) response spectra and smoothed Fourier amplitude spectra. Statistics of amplitudes of PSA and of low-pass filtered acceleration and velocity have also been determined. Amplitudes recorded at the Kawaguchi-cho station (40 km) at 5-6 second period from the 1964 Niigata earthquake (Mw=8.3) are within ~20% of the current empirical limit of ground motions observed from all earthquakes in the data set including those from the near field. An even more impressive example is that amplitudes recorded at the SCT station (~300 km from the fault) with period of about 2 seconds, during the 1985 Michoacan, Mexico, earthquake (Mw=8.0), are about the same as the current empirical limit of ground motions observed from near field records. These examples support the idea that the hazard caused by long-period ground motions, amplified by basins and site conditions, is not sufficiently appreciated. Reference: Anderson, J. G. (2010), Bull. Seism. Soc. Am. 100, 1-36.

Earthquake Damping Device for Steel Frame

NASA Astrophysics Data System (ADS)

Zamri Ramli, Mohd; Delfy, Dezoura; Adnan, Azlan; Torman, Zaida

2018-04-01

Structures such as buildings, bridges and towers are prone to collapse when natural phenomena like earthquake occurred. Therefore, many design codes are reviewed and new technologies are introduced to resist earthquake energy especially on building to avoid collapse. The tuned mass damper is one of the earthquake reduction products introduced on structures to minimise the earthquake effect. This study aims to analyse the effectiveness of tuned mass damper by experimental works and finite element modelling. The comparisons are made between these two models under harmonic excitation. Based on the result, it is proven that installing tuned mass damper will reduce the dynamic response of the frame but only in several input frequencies. At the highest input frequency applied, the tuned mass damper failed to reduce the responses. In conclusion, in order to use a proper design of damper, detailed analysis must be carried out to have sufficient design based on the location of the structures with specific ground accelerations.

PERFORMANCE OF AN EARTHQUAKE EXCITED ROOF DIAPHRAGM.

USGS Publications Warehouse

Celebi, M.; Brady, G.; Safak, E.; Converse, A.; ,

1986-01-01

The objective of this paper is to study the earthquake performance of the roof diaphragm of the West Valley College gymnasium in Saratoga, California through a complete set of acceleration records obtained during the 24 April 1984 Morgan Hill Earthquake (M equals 6. 1). The roof diaphragm of the 112 ft. multiplied by 144 ft. rectangular, symmetric gymnasium consists of 3/8 in. plywood over tongue-and-groove sheathing attached to steel trusses supported by reinforced concrete columns and walls. Three sensors placed in the direction of each of the axes of the diaphragm facilitate the evaluation of in-plane deformation of the diaphragm. Other sensors placed at ground level measure vertical and horizontal motion of the building floor, and consequently allow the calculation of the relative motion of the diaphragm with respect to the ground level.

Induced earthquake during the 2016 Kumamoto earthquake (Mw7.0): Importance of real-time shake monitoring for Earthquake Early Warning

NASA Astrophysics Data System (ADS)

Hoshiba, M.; Ogiso, M.

2016-12-01

Sequence of the 2016 Kumamoto earthquakes (Mw6.2 on April 14, Mw7.0 on April 16, and many aftershocks) caused a devastating damage at Kumamoto and Oita prefectures, Japan. During the Mw7.0 event, just after the direct S waves passing the central Oita, another M6 class event occurred there more than 80 km apart from the Mw7.0 event. The M6 event is interpreted as an induced earthquake; but it brought stronger shaking at the central Oita than that from the Mw7.0 event. We will discuss the induced earthquake from viewpoint of Earthquake Early Warning. In terms of ground shaking such as PGA and PGV, the Mw7.0 event is much smaller than those of the M6 induced earthquake at the central Oita (for example, 1/8 smaller at OIT009 station for PGA), and then it is easy to discriminate two events. However, PGD of the Mw7.0 is larger than that of the induced earthquake, and its appearance is just before the occurrence of the induced earthquake. It is quite difficult to recognize the induced earthquake from displacement waveforms only, because the displacement is strongly contaminated by that of the preceding Mw7.0 event. In many methods of EEW (including current JMA EEW system), magnitude is used for prediction of ground shaking through Ground Motion Prediction Equation (GMPE) and the magnitude is often estimated from displacement. However, displacement magnitude does not necessarily mean the best one for prediction of ground shaking, such as PGA and PGV. In case of the induced earthquake during the Kumamoto earthquake, displacement magnitude could not be estimated because of the strong contamination. Actually JMA EEW system could not recognize the induced earthquake. One of the important lessons we learned from eight years' operation of EEW is an issue of the multiple simultaneous earthquakes, such as aftershocks of the 2011 Mw9.0 Tohoku earthquake. Based on this lesson, we have proposed enhancement of real-time monitor of ground shaking itself instead of rapid estimation of

The 26 January 2001 M 7.6 Bhuj, India, earthquake: Observed and predicted ground motions

USGS Publications Warehouse

Hough, S.E.; Martin, S.; Bilham, R.; Atkinson, G.M.

2002-01-01

the average effects. The discrepancy may also be partly attributable to the inadequacy of the empirical relationship between MMI and peak ground acceleration (PGA), when applied to India. The MMI-PGA relationship was developed using data from California earthquakes, which might have a systematically different stress drop and therefore, a different frequency content than intraplate events. When a relationship between response spectra and MMI is used, we obtain larger predicted MMI values, in better agreement with the observations.

Soil amplification maps for estimating earthquake ground motions in the Central US

USGS Publications Warehouse

Bauer, R.A.; Kiefer, J.; Hester, N.

2001-01-01

The State Geologists of the Central United States Earthquake Consortium (CUSEC) are developing maps to assist State and local emergency managers and community officials in evaluating the earthquake hazards for the CUSEC region. The state geological surveys have worked together to produce a series of maps that show seismic shaking potential for eleven 1 X 2 degree (scale 1:250 000 or 1 in. ??? 3.9 miles) quadrangles that cover the high-risk area of the New Madrid Seismic Zone in eight states. Shear wave velocity values for the surficial materials were gathered and used to classify the soils according to their potential to amplify earthquake ground motions. Geologic base maps of surficial materials or 3-D material maps, either existing or produced for this project, were used in conjunction with shear wave velocities to classify the soils for the upper 15-30 m. These maps are available in an electronic form suitable for inclusion in the federal emergency management agency's earthquake loss estimation program (HAZUS). ?? 2001 Elsevier Science B.V. All rights reserved.

Earthquake forewarning — A multidisciplinary challenge from the ground up to space

NASA Astrophysics Data System (ADS)

Freund, Friedemann

2013-08-01

Most destructive earthquakes nucleate at between 5-7 km and about 35-40 km depth. Before earthquakes, rocks are subjected to increasing stress. Not every stress increase leads to rupture. To understand pre-earthquake phenomena we note that igneous and high-grade metamorphic rocks contain defects which, upon stressing, release defect electrons in the oxygen anion sublattice, known as positive holes. These charge carriers are highly mobile, able to flow out of stressed rocks into surrounding unstressed rocks. They form electric currents, which emit electromagnetic radiation, sometimes in pulses, sometimes sustained. The arrival of positive holes at the ground-air interface can lead to air ionization, often exclusively positive. Ionized air rising upward can lead to cloud condensation. The upward flow of positive ions can lead to instabilities in the mesosphere, to mesospheric lightning, to changes in the Total Electron Content (TEC) at the lower edge of the ionosphere, and electric field turbulences. Advances in deciphering the earthquake process can only be achieved in a broadly multidisciplinary spirit.

Effects of Long-Period Ground Motion on Distant Basins: The 1906 San Francisco Earthquake and Comparison with Japanese Cases

NASA Astrophysics Data System (ADS)

Koketsu, K.; Ikegami, Y.; Kimura, T.; Miyake, H.

2006-12-01

Large earthquakes at shallow depths can excite long-period ground motions affecting large-scale structures in distant sedimentary basins. For example, the 1985 Michoacan, Mexico, earthquake caused 20,000 fatalities in Mexico City at an epicentral distance of 400 km, and the 2003 Tokachi-oki, Japan, earthquake damaged oil tanks in the Yufutsu basin 250 km away (Koketsu et al., 2005). Similar long-range effects were also observed during the 2004 off Kii-peninsula earthquake (Miyake and Koketsu, 2005). In order to examine whether the 1906 San Francisco earthquake and the Los Angeles (LA) basin are in such a case or not, we simulate long- period ground motions in almost whole California caused by the earthquake using the finite element method (FEM) with a voxel mesh (Koketsu et al., 2004). The LA basin is located at a distance of about 600 km from the source region of the 1906 San Francisco earthquake. The 3-D heterogeneous velocity structure model for the ground motion simulation is constructed based on the SCEC Unified Velocity Model for southern California and USGS Bay Area Velocity Model for northern California. The source model of the earthquake is constructed according to Wald et al. (1993). Since we use a mesh with intervals of 500m, the voxel FEM can compute seismic waves with frequencies lower than 0.2 Hz. Although ground motions in the south of the source region are smaller than those in the north because of the rupture directivity effect, we can see fairly developed long- period ground motions in the LA basin in the preliminary result of Kimura et al. (2006). However, we obtained only 8cm/s and 25km/s for PGV and peak velocity response spectrum in the LA basin. We modeled the velocity structure up to a depth of only 20km neglecting the Moho reflections, and we did not include layers with Vs smaller than 1.0 km/s. In this study, we include deeper parts and use a more accurate velocity structure model with low-velocity sediments of Vs smaller than 1.0 km/s.

Geological controls on hillslope-failure mechanisms during the 2010-2011 earthquake sequence in suburban Christchurch, New Zealand

NASA Astrophysics Data System (ADS)

McSaveney, M. J.; Massey, C. I.; Wang, G.

2012-12-01

Parts of the city of Christchurch NZ were severely damaged when a series of shallow aftershocks from the Mw 7.1 Darfield earthquake of 4 Sept. 2010 occurred beneath the city. Hillside suburbs are on the flanks of an extinct and deeply dissected Miocene basalt volcano which is widely mantled by Pleistocene loess. Portions of the lower flanks of the volcano have been cliffed by late Holocene marine erosion. Highly prized cliff-top homes overlook the city with a backdrop of the Southern Alps, or a seascape of the south Pacific Ocean. Here we discuss how various hillslope materials responded in different ways to the unusually high ground accelerations in the hillside suburbs. Most ground damage occurred in two major aftershocks: the Mw 6.2 Christchurch earthquake of 22 Feb. 2011, in which 184 people died, and a Mw 6.2 aftershock of 13 June 2011. Ground accelerations in these earthquakes were recorded locally in excess of 2 g. Significant ground damage occurred in 3 other strong aftershocks, although minor rockfalls were observed in many smaller aftershocks of which there were thousands. In the highest ground accelerations, many loose hillside objects were thrown into the air. More than 5000 loose basalt boulders were thrown or toppled from steep slopes to roll through residential properties on the slopes below. In addition, cliff tops and faces crumbled into debris avalanches. In the 13 June earthquake a geotechnical witness on a cliff top described ground cracks opening and closing around him as he scrambled off the collapsing cliff edge during the strong cyclic shaking. Loess landslides were a relative minor but damaging component. Dynamic ring-shear testing showed that the loess fails during amplified strong ground shaking, but shear displacement stops soon after, so that the earthquake-triggered loess landslides move only during strong earthquakes. Detected minor lateral movement in strongly weathered basaltic tuff and basaltic lava breccia is a cause of concern

A New Distance Metric in Ground Motion Prediction Equations Based On Array Back-Projections

NASA Astrophysics Data System (ADS)

Feng, T.; Meng, L.

2017-12-01

Traditional Ground Motion Prediction Equations (GMPEs) measure the distances either relative to the epicenter (Repi) or the hypocenter (Rhyp) assuming point-sources, or relative to the closest point of the fault rupture (Rrup) or its surface projection (Rjb) to account for finite earthquake dimensions. However, it has long been proven that for large megathrust earthquakes (M>8), the over-simplification of the earthquake source characteristics in these distance metrics result in significant bias and uncertainty of the ground motion predictions. Recent advances in earthquake source imaging of major subduction earthquakes highlight the frequency-dependent and depth-varying seismic radiations at the plate interfaces. Low-frequency energy mainly emanated from the shallower portion of the megathrusts while dominant high-frequency energy often radiates from the deeper portion of the megathrust. In the 2011 Tohoku-Oki earthquake, all these distance metrics produce severe biases, underestimating the ground accelerations at short distances (<100km) and overestimating them at long distances (>100km). This phenomenon motivates an alternative distance metric based on the array back-projection (BP) technique that effectively captures regions releasing high-frequency energy. Herein, we define Rbp as the distance between nearest BP radiators and the station sites. We studied five large earthquakes in Japan, and found that Rbp outperforms conventional distance metrics in predicting the Psa (Pseudo Spectral Acceleration) in the high-frequency band (0.5-4 Hz). And at low frequencies (0.1-0.5Hz), we find that Rhyp produces better fits to the Psa spectrum. Thus, we propose to combine Rhyp and Rbp in low-frequency (0.1-0.5Hz) and high-frequency (0.5-4 Hz) range to improve the GMPEs. We consider that Rbp reflects the high-frequency characters of the rupture that are complementary to conventional GMPE distance metrics and a more suitable ground motion predictors in many cases. Based on

It's Our Fault: better defining earthquake risk in Wellington, New Zealand

NASA Astrophysics Data System (ADS)

Van Dissen, R.; Brackley, H. L.; Francois-Holden, C.

2012-12-01

increasing the region's resilience to earthquakes. We present latest results on ground motion simulations for large plate interface earthquakes under Wellington in terms of response spectra and acceleration time histories. We derive realistic broadband accelerograms based on a stochastic modelling technique. First we characterise the potential interface rupture area based on previous geodetically-derived estimates interface of slip deficit. Then, we entertain a suitable range of source parameters, including various rupture areas, moment magnitudes, stress drops, slip distributions and rupture propagation directions. The resulting rupture scenarios all produce long duration shaking, and peak ground accelerations that, typically, range between 0.2-0.7 g in Wellington city. Many of these scenarios also produce long period motions that are currently not captured by the current NZ design spectra.

Fault rupture process and strong ground motion simulation of the 2014/04/01 Northern Chile (Pisagua) earthquake (Mw8.2)

NASA Astrophysics Data System (ADS)

Pulido Hernandez, N. E.; Suzuki, W.; Aoi, S.

2014-12-01

A megathrust earthquake occurred in Northern Chile in April 1, 2014, 23:46 (UTC) (Mw 8.2), in a region that had not experienced a major earthquake since the great 1877 (~M8.6) event. This area had been already identified as a mature seismic gap with a strong interseismic coupling inferred from geodetic measurements (Chlieh et al., JGR, 2011 and Metois et al., GJI, 2013). We used 48 components of strong motion records belonging to the IPOC network in Northern Chile to investigate the source process of the M8.2 Pisagua earthquake. Acceleration waveforms were integrated to get velocities and filtered between 0.02 and 0.125 Hz. We assumed a single fault plane segment with an area of 180 km by 135 km, a strike of 357, and a dip of 18 degrees (GCMT). We set the starting point of rupture at the USGS hypocenter (19.610S, 70.769W, depth 25km), and employed a multi-time-window linear waveform inversion method (Hartzell and Heaton, BSSA, 1983), to derive the rupture process of the Pisagua earthquake. Our results show a slip model characterized by one large slip area (asperity) localized 50 km south of the epicenter, a peak slip of 10 m and a total seismic moment of 2.36 x 1021Nm (Mw 8.2). Fault rupture slowly propagated to the south in front of the main asperity for the initial 25 seconds, and broke it by producing a strong acceleration stage. The fault plane rupture velocity was in average 2.9 km/s. Our calculations show an average stress drop of 4.5MPa for the entire fault rupture area and 12MPa for the asperity area. We simulated the near-source strong ground motion records in a broad frequency band (0.1 ~ 20 Hz), to investigate a possible multi-frequency fault rupture process as the one observed in recent mega-thrust earthquakes such as the 2011 Tohoku-oki (M9.0). Acknowledgments Strong motion data was kindly provided by Chile University as well as the IPOC (Integrated Plate boundary Observatory Chile).

Earthquake hazard and risk assessment based on Unified Scaling Law for Earthquakes: Greater Caucasus and Crimea

NASA Astrophysics Data System (ADS)

Kossobokov, Vladimir G.; Nekrasova, Anastasia K.

2018-05-01

We continue applying the general concept of seismic risk analysis in a number of seismic regions worldwide by constructing regional seismic hazard maps based on morphostructural analysis, pattern recognition, and the Unified Scaling Law for Earthquakes (USLE), which generalizes the Gutenberg-Richter relationship making use of naturally fractal distribution of earthquake sources of different size in a seismic region. The USLE stands for an empirical relationship log10 N(M, L) = A + B·(5 - M) + C·log10 L, where N(M, L) is the expected annual number of earthquakes of a certain magnitude M within a seismically prone area of linear dimension L. We use parameters A, B, and C of USLE to estimate, first, the expected maximum magnitude in a time interval at seismically prone nodes of the morphostructural scheme of the region under study, then map the corresponding expected ground shaking parameters (e.g., peak ground acceleration, PGA, or macro-seismic intensity). After a rigorous verification against the available seismic evidences in the past (usually, the observed instrumental PGA or the historically reported macro-seismic intensity), such a seismic hazard map is used to generate maps of specific earthquake risks for population, cities, and infrastructures (e.g., those based on census of population, buildings inventory). The methodology of seismic hazard and risk assessment is illustrated by application to the territory of Greater Caucasus and Crimea.

A global earthquake discrimination scheme to optimize ground-motion prediction equation selection

USGS Publications Warehouse

Garcia, Daniel; Wald, David J.; Hearne, Michael

2012-01-01

We present a new automatic earthquake discrimination procedure to determine in near-real time the tectonic regime and seismotectonic domain of an earthquake, its most likely source type, and the corresponding ground-motion prediction equation (GMPE) class to be used in the U.S. Geological Survey (USGS) Global ShakeMap system. This method makes use of the Flinn–Engdahl regionalization scheme, seismotectonic information (plate boundaries, global geology, seismicity catalogs, and regional and local studies), and the source parameters available from the USGS National Earthquake Information Center in the minutes following an earthquake to give the best estimation of the setting and mechanism of the event. Depending on the tectonic setting, additional criteria based on hypocentral depth, style of faulting, and regional seismicity may be applied. For subduction zones, these criteria include the use of focal mechanism information and detailed interface models to discriminate among outer-rise, upper-plate, interface, and intraslab seismicity. The scheme is validated against a large database of recent historical earthquakes. Though developed to assess GMPE selection in Global ShakeMap operations, we anticipate a variety of uses for this strategy, from real-time processing systems to any analysis involving tectonic classification of sources from seismic catalogs.

Up-to-date Probabilistic Earthquake Hazard Maps for Egypt

NASA Astrophysics Data System (ADS)

Gaber, Hanan; El-Hadidy, Mahmoud; Badawy, Ahmed

2018-04-01

An up-to-date earthquake hazard analysis has been performed in Egypt using a probabilistic seismic hazard approach. Through the current study, we use a complete and homogenous earthquake catalog covering the time period between 2200 BC and 2015 AD. Three seismotectonic models representing the seismic activity in and around Egypt are used. A logic-tree framework is applied to allow for the epistemic uncertainty in the declustering parameters, minimum magnitude, seismotectonic setting and ground-motion prediction equations. The hazard analysis is performed for a grid of 0.5° × 0.5° in terms of types of rock site for the peak ground acceleration (PGA) and spectral acceleration at 0.2-, 0.5-, 1.0- and 2.0-s periods. The hazard is estimated for three return periods (72, 475 and 2475 years) corresponding to 50, 10 and 2% probability of exceedance in 50 years. The uniform hazard spectra for the cities of Cairo, Alexandria, Aswan and Nuwbia are constructed. The hazard maps show that the highest ground acceleration values are expected in the northeastern part of Egypt around the Gulf of Aqaba (PGA up to 0.4 g for return period 475 years) and in south Egypt around the city of Aswan (PGA up to 0.2 g for return period 475 years). The Western Desert of Egypt is characterized by the lowest level of hazard (PGA lower than 0.1 g for return period 475 years).

Ground motion attenuation during M 7.1 Darfield and M 6.2 Christchurch, New Zealand, earthquakes and performance of global Ppedictive models

USGS Publications Warehouse

Segou, Margaret; Kalkan, Erol

2011-01-01

fault with M 6.2, followed by a second event (M 6.9), releasing the largest portion of the energy on the right-lateral Greendale fault. The third sub-event (M 5.7) is due to a reverse fault with a right-lateral component (Holden et al. 2011). The Christchurch earthquake occurred on an oblique thrust fault. The comparison of spectral acceleration values at stations near Christchurch reveals that the second event produced much larger amplitudes of shaking than the Darfield event due to its proximity to the epicenter. Both events resulted in noticeably large amplitudes of the vertical motion, often exceeding horizontal motion in the near-fault area. The vertical motions, showing asymmetric acceleration traces and pulses, reached 1.26 g during the Darfield earthquake and 2.2 g during the Christchurch event. These events were recorded by more than 100 strong motion stations operated by the Institute of Geological and Nuclear Sciences (http://www.geonet.org.nz/). Using the processed data from these stations, peak ground acceleration (PGA) and 5%-damped spectral acceleration values at 0.3, 1, and 3 s are used for performance evaluation of the global ground motion predictive equations (GMPEs). The selected GMPEs are the Next Generation Attenuation (NGA) models of Abrahamson and Silva (2008), Boore and Atkinson (2008), Campbell and Bozorgnia (2008), and Chiou and Youngs (2008). The Graizer and Kalkan (2007, 2009) model, which is based on the NGA project database, is also included. These GMPEs are abbreviated respectively as AS08, BA08, CB08, CY08, and GK07. Because they have been used widely for seismic hazard analysis for crustal earthquakes, their performance assessment becomes a critical issue especially for immediate response and recovery planning after major events. The occurrence of aftershocks similar to the Christchurch event will most probably control seismic hazard in the broader area, as confirmed by the recent M 6.0 event on June 13, 2011.

Seismic Hazard and Ground Motion Characterization at the Itoiz Dam (Northern Spain)

NASA Astrophysics Data System (ADS)

Rivas-Medina, A.; Santoyo, M. A.; Luzón, F.; Benito, B.; Gaspar-Escribano, J. M.; García-Jerez, A.

2012-08-01

This paper presents a new hazard-consistent ground motion characterization of the Itoiz dam site, located in Northern Spain. Firstly, we propose a methodology with different approximation levels to the expected ground motion at the dam site. Secondly, we apply this methodology taking into account the particular characteristics of the site and of the dam. Hazard calculations were performed following the Probabilistic Seismic Hazard Assessment method using a logic tree, which accounts for different seismic source zonings and different ground-motion attenuation relationships. The study was done in terms of peak ground acceleration and several spectral accelerations of periods coinciding with the fundamental vibration periods of the dam. In order to estimate these ground motions we consider two different dam conditions: when the dam is empty ( T = 0.1 s) and when it is filled with water to its maximum capacity ( T = 0.22 s). Additionally, seismic hazard analysis is done for two return periods: 975 years, related to the project earthquake, and 4,975 years, identified with an extreme event. Soil conditions were also taken into account at the site of the dam. Through the proposed methodology we deal with different forms of characterizing ground motion at the study site. In a first step, we obtain the uniform hazard response spectra for the two return periods. In a second step, a disaggregation analysis is done in order to obtain the controlling earthquakes that can affect the dam. Subsequently, we characterize the ground motion at the dam site in terms of specific response spectra for target motions defined by the expected values SA ( T) of T = 0.1 and 0.22 s for the return periods of 975 and 4,975 years, respectively. Finally, synthetic acceleration time histories for earthquake events matching the controlling parameters are generated using the discrete wave-number method and subsequently analyzed. Because of the short relative distances between the controlling

Estimation of ground motion parameters

USGS Publications Warehouse

Boore, David M.; Joyner, W.B.; Oliver, A.A.; Page, R.A.

1978-01-01

Strong motion data from western North America for earthquakes of magnitude greater than 5 are examined to provide the basis for estimating peak acceleration, velocity, displacement, and duration as a function of distance for three magnitude classes. A subset of the data (from the San Fernando earthquake) is used to assess the effects of structural size and of geologic site conditions on peak motions recorded at the base of structures. Small but statistically significant differences are observed in peak values of horizontal acceleration, velocity and displacement recorded on soil at the base of small structures compared with values recorded at the base of large structures. The peak acceleration tends to b3e less and the peak velocity and displacement tend to be greater on the average at the base of large structures than at the base of small structures. In the distance range used in the regression analysis (15-100 km) the values of peak horizontal acceleration recorded at soil sites in the San Fernando earthquake are not significantly different from the values recorded at rock sites, but values of peak horizontal velocity and displacement are significantly greater at soil sites than at rock sites. Some consideration is given to the prediction of ground motions at close distances where there are insufficient recorded data points. As might be expected from the lack of data, published relations for predicting peak horizontal acceleration give widely divergent estimates at close distances (three well known relations predict accelerations between 0.33 g to slightly over 1 g at a distance of 5 km from a magnitude 6.5 earthquake). After considering the physics of the faulting process, the few available data close to faults, and the modifying effects of surface topography, at the present time it would be difficult to accept estimates less than about 0.8 g, 110 cm/s, and 40 cm, respectively, for the mean values of peak acceleration, velocity, and displacement at rock sites

Responses of buried corrugated metal pipes to earthquakes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davis, C.A.; Bardet, J.P.

2000-01-01

This study describes the results of field investigations and analyses carried out on 61 corrugated metal pipes (CMP) that were shaken by the 1994 Northridge earthquake. These CMPs, which include 29 small-diameter (below 107 cm) CMPs and 32 large-diameter (above 107 cm) CMPs, are located within a 10 km{sup 2} area encompassing the Van Normal Complex in the Northern San Fernando Valley, in Los Angeles, California. During the Northridge earthquake, ground movements were extensively recorded within the study area. Twenty-eight of the small-diameter CMPs performed well while the 32 large-diameter CMPs underwent performances ranging from no damage to complete collapse.more » The main cause of damage to the large-diameter CMPs was found to be the large ground strains. Based on this unprecedented data set, the factors controlling the seismic performance of the 32 large-diameter CMPs were identified and framed into a pseudostatic analysis method for evaluating the response of large diameter flexible underground pipes subjected to ground strain. The proposed analysis, which is applicable to transient and permanent strains, is capable of describing the observed performance of large-diameter CMPs during the 1994 Northridge earthquake. It indicates that peak ground velocity is a more reliable parameter for analyzing pipe damage than is peak ground acceleration. Results of this field investigation and analysis are useful for the seismic design and strengthening of flexible buried conduits.« less

Ground motion-simulations of 1811-1812 New Madrid earthquakes, central United States

USGS Publications Warehouse

Ramirez-Guzman, L.; Graves, Robert; Olsen, Kim B.; Boyd, Oliver; Cramer, Chris H.; Hartzell, Stephen; Ni, Sidao; Somerville, Paul G.; Williams, Robert; Zhong, Jinquan

2015-01-01

The region covered by our simulation domain encompasses a large portion of the CUS centered on the NMSZ, including several major metropolitan areas. Based on our simulations, more than eight million people living and working near the NMSZ would experience potentially damaging ground motion and modified Mercalli intensities ranging from VI to VIII if a repeat of the 1811–1812 earthquakes occurred today. Moreover, the duration of strong ground shaking in the greater Memphis metropolitan area could last from 30 to more than 60 s, depending on the magnitude and epicenter.

Local soil effects on the Ground Motion Prediction model for the Racha region in Georgia

NASA Astrophysics Data System (ADS)

Jorjiashvili, N.; Shengelia, I.; Otinashvili, M.; Tvaliashvili, A.

2016-12-01

The Caucasus is a region of numerous natural hazards and ensuing disasters. Analysis of the losses due to past disasters indicates those most catastrophic in the region have historically been due to strong earthquakes. Estimation of expected ground motion is a fundamental earthquake hazard assessment. The most commonly used parameter for attenuation relation is the peak ground acceleration because this parameter gives useful information for Seismic Hazard Assessment that was selected for the analysis. One of the most important topics that have a significant influence on earthquake records is the site ground conditions that are the main issue of the study because the same earthquake recorded at the same distance may cause different damage according to ground conditions. In the study earthquake records were selected for the Racha region in Georgia which has the highest seismic activity in the region. Next, new GMP models are obtained based on new digital data recorded in the same area. After removing the site effect the earthquake records on the rock site were obtained. Thus, two GMP models were obtained: one for the ground surface and the other for the rock site. At the end, comparison was done for the both models in order to analyze the influence of the local soil conditions on the GMP model.

QuakeUp: An advanced tool for a network-based Earthquake Early Warning system

NASA Astrophysics Data System (ADS)

Zollo, Aldo; Colombelli, Simona; Caruso, Alessandro; Elia, Luca; Brondi, Piero; Emolo, Antonio; Festa, Gaetano; Martino, Claudio; Picozzi, Matteo

2017-04-01

The currently developed and operational Earthquake Early warning, regional systems ground on the assumption of a point-like earthquake source model and 1-D ground motion prediction equations to estimate the earthquake impact. Here we propose a new network-based method which allows for issuing an alert based upon the real-time mapping of the Potential Damage Zone (PDZ), e.g. the epicentral area where the peak ground velocity is expected to exceed the damaging or strong shaking levels with no assumption about the earthquake rupture extent and spatial variability of ground motion. The platform includes the most advanced techniques for a refined estimation of the main source parameters (earthquake location and magnitude) and for an accurate prediction of the expected ground shaking level. The new software platform (QuakeUp) is under development at the Seismological Laboratory (RISSC-Lab) of the Department of Physics at the University of Naples Federico II, in collaboration with the academic spin-off company RISS s.r.l., recently gemmated by the research group. The system processes the 3-component, real-time ground acceleration and velocity data streams at each station. The signal quality is preliminary assessed by checking the signal-to-noise ratio both in acceleration, velocity and displacement and through dedicated filtering algorithms. For stations providing high quality data, the characteristic P-wave period (τ_c) and the P-wave displacement, velocity and acceleration amplitudes (P_d, Pv and P_a) are jointly measured on a progressively expanded P-wave time window. The evolutionary measurements of the early P-wave amplitude and characteristic period at stations around the source allow to predict the geometry and extent of PDZ, but also of the lower shaking intensity regions at larger epicentral distances. This is done by correlating the measured P-wave amplitude with the Peak Ground Velocity (PGV) and Instrumental Intensity (I_MM) and by mapping the measured and

Recent damaging earthquakes in Japan, 2003-2008

USGS Publications Warehouse

Kayen, Robert E

2008-01-01

landslides resulted, in part, from heavy rain associated with Typhoon Tokage. The earthquake forced more than 100,000 people into temporary shelters, and as many as 10,000 displaced from their upland homes for several years. Total damages was estimated by Japanese authorities at US$40 billion, making this the second most costly disaster in history, after the 1995 Kobe earth-quake. The 2003 Tokachi-Oki earthquake was the third event of magnitude 8.0+ to strike the southeastern portion of Hokkaido in the last 50 years. The event produced tsunami run-ups along the shoreline of southern Hokkaido that reached maximum heights of 4 meters. Accelerations recorded by seismic networks of Hokkaido indicated a high intensity motion region from Hiroo area to Kushiro City, with a PGA values in the range of 0.35 to 0.6g. Despite high acceleration levels, the observed ground failure, liquefaction, structural, port, and lifeline damages were remarkably light.

Estimation of Peak Ground Acceleration (PGA) for Peninsular Malaysia using geospatial approach

NASA Astrophysics Data System (ADS)

Nouri Manafizad, Amir; Pradhan, Biswajeet; Abdullahi, Saleh

2016-06-01

Among the various types of natural disasters, earthquake is considered as one of the most destructive events which impose a great amount of human fatalities and economic losses. Visualization of earthquake events and estimation of peak ground motions provides a strong tool for scientists and authorities to predict and mitigate the aftereffects of earthquakes. In addition it is useful for some businesses like insurance companies to evaluate the amount of investing risk. Although Peninsular Malaysian is situated in the stable part of Sunda plate, it is seismically influenced by very active earthquake sources of Sumatra's fault and subduction zones. This study modelled the seismic zones and estimates maximum credible earthquake (MCE) based on classified data for period 1900 to 2014. The deterministic approach was implemented for the analysis. Attenuation equations were used for two zones. Results show that, the PGA produced from subduction zone is from 2-64 (gal) and from the fault zone varies from 1-191(gal). In addition, the PGA generated from fault zone is more critical than subduction zone for selected seismic model.

Earthquake Hazard and Risk Assessment based on Unified Scaling Law for Earthquakes: Altai-Sayan Region

NASA Astrophysics Data System (ADS)

Kossobokov, V. G.; Nekrasova, A.

2017-12-01

We continue applying the general concept of seismic risk analysis in a number of seismic regions worldwide by constructing regional seismic hazard maps based on morphostructural analysis, pattern recognition, and the Unified Scaling Law for Earthquakes, USLE, which generalizes the Gutenberg-Richter relationship making use of naturally fractal distribution of earthquake sources of different size in a seismic region. The USLE stands for an empirical relationship log10N(M, L) = A + B·(5 - M) + C·log10L, where N(M, L) is the expected annual number of earthquakes of a certain magnitude M within an seismically prone area of linear dimension L. We use parameters A, B, and C of USLE to estimate, first, the expected maximum credible magnitude in a time interval at seismically prone nodes of the morphostructural scheme of the region under study, then map the corresponding expected ground shaking parameters (e.g. peak ground acceleration, PGA, or macro-seismic intensity etc.). After a rigorous testing against the available seismic evidences in the past (usually, the observed instrumental PGA or the historically reported macro-seismic intensity), such a seismic hazard map is used to generate maps of specific earthquake risks for population, cities, and infrastructures (e.g., those based on census of population, buildings inventory, etc.). This, USLE based, methodology of seismic hazard and risks assessment is applied to the territory of Altai-Sayan Region, of Russia. The study supported by the Russian Science Foundation Grant No. 15-17-30020.

Accelerations from the September 5, 2012 (Mw=7.6) Nicoya, Costa Rica Earthquake

NASA Astrophysics Data System (ADS)

Simila, G. W.; Quintero, R.; Burgoa, B.; Mohammadebrahim, E.; Segura, J.

2013-05-01

reports were of damage to homes, bridges, roads, aqueducts, schools and public buildings. There were 12 structures reported with damages in hospitals and health care sites, specifically in Hojancha, Nandayure, Nicoya, Santa Cruz and Puntarenas. There are no reports of deaths from the earthquake and only 78 injured and a total of 1474 people mobilized, which includes hospital evacuations and preventive transfers. 223 schools were reported with various damages, mostly in Santa Cruz, Nicoya, Carrillo, Nandayure, and Puntarenas. A total of 98 homes were reported with severe damage, 805 with moderate damage and 87 with minor damage. In general, the buildings in the Nicoya Peninsula (where the highest intensities were reported) endured the Nicoya Earthquake. Also, acceleration data from OVSICORI, UCR, LIS-UCR, and the Seismic Strong Motion Array Project (SSMAP) show a range of accelerations (500 - 10 cm/sec2) for distance range of 30-250 km, respectively.

SMSIM--Fortran programs for simulating ground motions from earthquakes: Version 2.0.--a revision of OFR 96-80-A

USGS Publications Warehouse

Boore, David M.

2000-01-01

A simple and powerful method for simulating ground motions is based on the assumption that the amplitude of ground motion at a site can be specified in a deterministic way, with a random phase spectrum modified such that the motion is distributed over a duration related to the earthquake magnitude and to distance from the source. This method of simulating ground motions often goes by the name "the stochastic method." It is particularly useful for simulating the higher-frequency ground motions of most interest to engineers, and it is widely used to predict ground motions for regions of the world in which recordings of motion from damaging earthquakes are not available. This simple method has been successful in matching a variety of ground-motion measures for earthquakes with seismic moments spanning more than 12 orders of magnitude. One of the essential characteristics of the method is that it distills what is known about the various factors affecting ground motions (source, path, and site) into simple functional forms that can be used to predict ground motions. SMSIM is a set of programs for simulating ground motions based on the stochastic method. This Open-File Report is a revision of an earlier report (Boore, 1996) describing a set of programs for simulating ground motions from earthquakes. The programs are based on modifications I have made to the stochastic method first introduced by Hanks and McGuire (1981). The report contains source codes, written in Fortran, and executables that can be used on a PC. Programs are included both for time-domain and for random vibration simulations. In addition, programs are included to produce Fourier amplitude spectra for the models used in the simulations and to convert shear velocity vs. depth into frequency-dependent amplification. The revision to the previous report is needed because the input and output files have changed significantly, and a number of new programs have been included in the set.

Make an Earthquake: Ground Shaking!

ERIC Educational Resources Information Center

Savasci, Funda

2011-01-01

The main purposes of this activity are to help students explore possible factors affecting the extent of the damage of earthquakes and learn the ways to reduce earthquake damages. In these inquiry-based activities, students have opportunities to develop science process skills and to build an understanding of the relationship among science,…

Evidence for Ancient Mesoamerican Earthquakes

NASA Astrophysics Data System (ADS)

Kovach, R. L.; Garcia, B.

2001-12-01

Evidence for past earthquake damage at Mesoamerican ruins is often overlooked because of the invasive effects of tropical vegetation and is usually not considered as a casual factor when restoration and reconstruction of many archaeological sites are undertaken. Yet the proximity of many ruins to zones of seismic activity would argue otherwise. Clues as to the types of damage which should be soughtwere offered in September 1999 when the M = 7.5 Oaxaca earthquake struck the ruins of Monte Alban, Mexico, where archaeological renovations were underway. More than 20 structures were damaged, 5 of them seriously. Damage features noted were walls out of plumb, fractures in walls, floors, basal platforms and tableros, toppling of columns, and deformation, settling and tumbling of walls. A Modified Mercalli Intensity of VII (ground accelerations 18-34 %b) occurred at the site. Within the diffuse landward extension of the Caribbean plate boundary zone M = 7+ earthquakes occur with repeat times of hundreds of years arguing that many Maya sites were subjected to earthquakes. Damage to re-erected and reinforced stelae, walls, and buildings were witnessed at Quirigua, Guatemala, during an expedition underway when then 1976 M = 7.5 Guatemala earthquake on the Motagua fault struck. Excavations also revealed evidence (domestic pttery vessels and skeleton of a child crushed under fallen walls) of an ancient earthquake occurring about the teim of the demise and abandonment of Quirigua in the late 9th century. Striking evidence for sudden earthquake building collapse at the end of the Mayan Classic Period ~A.D. 889 was found at Benque Viejo (Xunantunich), Belize, located 210 north of Quirigua. It is argued that a M = 7.5 to 7.9 earthquake at the end of the Maya Classic period centered in the vicinity of the Chixoy-Polochic and Motagua fault zones cound have produced the contemporaneous earthquake damage to the above sites. As a consequences this earthquake may have accelerated the

Earthquakes for Kids

MedlinePlus

... across a fault to learn about past earthquakes. Science Fair Projects A GPS instrument measures slow movements of the ground. Become an Earthquake Scientist Cool Earthquake Facts Today in Earthquake History A scientist stands in ...

Ground motion simulation for the 23 August 2011, Mineral, Virginia earthquake using physics-based and stochastic broadband methods

USGS Publications Warehouse

Sun, Xiaodan; Hartzell, Stephen; Rezaeian, Sanaz

2015-01-01

Three broadband simulation methods are used to generate synthetic ground motions for the 2011 Mineral, Virginia, earthquake and compare with observed motions. The methods include a physics‐based model by Hartzell et al. (1999, 2005), a stochastic source‐based model by Boore (2009), and a stochastic site‐based model by Rezaeian and Der Kiureghian (2010, 2012). The ground‐motion dataset consists of 40 stations within 600 km of the epicenter. Several metrics are used to validate the simulations: (1) overall bias of response spectra and Fourier spectra (from 0.1 to 10 Hz); (2) spatial distribution of residuals for GMRotI50 peak ground acceleration (PGA), peak ground velocity, and pseudospectral acceleration (PSA) at various periods; (3) comparison with ground‐motion prediction equations (GMPEs) for the eastern United States. Our results show that (1) the physics‐based model provides satisfactory overall bias from 0.1 to 10 Hz and produces more realistic synthetic waveforms; (2) the stochastic site‐based model also yields more realistic synthetic waveforms and performs superiorly for frequencies greater than about 1 Hz; (3) the stochastic source‐based model has larger bias at lower frequencies (<0.5  Hz) and cannot reproduce the varying frequency content in the time domain. The spatial distribution of GMRotI50 residuals shows that there is no obvious pattern with distance in the simulation bias, but there is some azimuthal variability. The comparison between synthetics and GMPEs shows similar fall‐off with distance for all three models, comparable PGA and PSA amplitudes for the physics‐based and stochastic site‐based models, and systematic lower amplitudes for the stochastic source‐based model at lower frequencies (<0.5  Hz).

Validation of simulated earthquake ground motions based on evolution of intensity and frequency content

USGS Publications Warehouse

Rezaeian, Sanaz; Zhong, Peng; Hartzell, Stephen; Zareian, Farzin

2015-01-01

Simulated earthquake ground motions can be used in many recent engineering applications that require time series as input excitations. However, applicability and validation of simulations are subjects of debate in the seismological and engineering communities. We propose a validation methodology at the waveform level and directly based on characteristics that are expected to influence most structural and geotechnical response parameters. In particular, three time-dependent validation metrics are used to evaluate the evolving intensity, frequency, and bandwidth of a waveform. These validation metrics capture nonstationarities in intensity and frequency content of waveforms, making them ideal to address nonlinear response of structural systems. A two-component error vector is proposed to quantify the average and shape differences between these validation metrics for a simulated and recorded ground-motion pair. Because these metrics are directly related to the waveform characteristics, they provide easily interpretable feedback to seismologists for modifying their ground-motion simulation models. To further simplify the use and interpretation of these metrics for engineers, it is shown how six scalar key parameters, including duration, intensity, and predominant frequency, can be extracted from the validation metrics. The proposed validation methodology is a step forward in paving the road for utilization of simulated ground motions in engineering practice and is demonstrated using examples of recorded and simulated ground motions from the 1994 Northridge, California, earthquake.

Orientation damage in the Christchurch cemeteries generated during the Christchurch earthquakes of 2010

NASA Astrophysics Data System (ADS)

Martín-González, Fidel; Perez-Lopez, Raul; Rodrigez-Pascua, Miguel Angel; Martin-Velazquez, Silvia

2014-05-01

more detailed correlation of the ground acceleration and the damages is being carried out. The orientation of the damage is not usually recorded after an earthquake; however, it can provide information on the orientation of the peak ground acceleration. Thus, when an earthquake occurs, the analysis of the damage orientation can provide information about the seismic source.

Rapid Earthquake Magnitude Estimation for Early Warning Applications

NASA Astrophysics Data System (ADS)

Goldberg, Dara; Bock, Yehuda; Melgar, Diego

2017-04-01

Earthquake magnitude is a concise metric that provides invaluable information about the destructive potential of a seismic event. Rapid estimation of magnitude for earthquake and tsunami early warning purposes requires reliance on near-field instrumentation. For large magnitude events, ground motions can exceed the dynamic range of near-field broadband seismic instrumentation (clipping). Strong motion accelerometers are designed with low gains to better capture strong shaking. Estimating earthquake magnitude rapidly from near-source strong-motion data requires integration of acceleration waveforms to displacement. However, integration amplifies small errors, creating unphysical drift that must be eliminated with a high pass filter. The loss of the long period information due to filtering is an impediment to magnitude estimation in real-time; the relation between ground motion measured with strong-motion instrumentation and magnitude saturates, leading to underestimation of earthquake magnitude. Using station displacements from Global Navigation Satellite System (GNSS) observations, we can supplement the high frequency information recorded by traditional seismic systems with long-period observations to better inform rapid response. Unlike seismic-only instrumentation, ground motions measured with GNSS scale with magnitude without saturation [Crowell et al., 2013; Melgar et al., 2015]. We refine the current magnitude scaling relations using peak ground displacement (PGD) by adding a large GNSS dataset of earthquakes in Japan. Because it does not suffer from saturation, GNSS alone has significant advantages over seismic-only instrumentation for rapid magnitude estimation of large events. The earthquake's magnitude can be estimated within 2-3 minutes of earthquake onset time [Melgar et al., 2013]. We demonstrate that seismogeodesy, the optimal combination of GNSS and seismic data at collocated stations, provides the added benefit of improving the sensitivity of

Ground Motion Prediction for M7+ scenarios on the San Andreas Fault using the Virtual Earthquake Approach

NASA Astrophysics Data System (ADS)

Denolle, M.; Dunham, E. M.; Prieto, G.; Beroza, G. C.

2013-05-01

There is no clearer example of the increase in hazard due to prolonged and amplified shaking in sedimentary, than the case of Mexico City in the 1985 Michoacan earthquake. It is critically important to identify what other cities might be susceptible to similar basin amplification effects. Physics-based simulations in 3D crustal structure can be used to model and anticipate those effects, but they rely on our knowledge of the complexity of the medium. We propose a parallel approach to validate ground motion simulations using the ambient seismic field. We compute the Earth's impulse response combining the ambient seismic field and coda-wave enforcing causality and symmetry constraints. We correct the surface impulse responses to account for the source depth, mechanism and duration using a 1D approximation of the local surface-wave excitation. We call the new responses virtual earthquakes. We validate the ground motion predicted from the virtual earthquakes against moderate earthquakes in southern California. We then combine temporary seismic stations on the southern San Andreas Fault and extend the point source approximation of the Virtual Earthquake Approach to model finite kinematic ruptures. We confirm the coupling between source directivity and amplification in downtown Los Angeles seen in simulations.

Conceptualizing ¬the Abstractions of Earthquakes Through an Instructional Sequence Using SeisMac and the Rapid Earthquake Viewer

NASA Astrophysics Data System (ADS)

Taber, J.; Hubenthal, M.; Wysession, M.

2007-12-01

Newsworthy earthquakes provide an engaging hook for students in Earth science classes, particularly when discussing their effects on people and the landscape. However, engaging students in an analysis of earthquakes that extends beyond death and damage, is frequently hampered by the abstraction of recorded ground motion data in the form of raw seismograms and the inability of most students to personally relate to ground accelerations. To overcome these challenges, an educational sequence has been developed using two software tools: SeisMac by Daniel Griscom, and the Rapid Earthquake Viewer (REV) developed by the University of South Carolina in collaboration with IRIS and DLESE. This sequence presents a unique opportunity for Earth Science teachers to "create" foundational experiences for students as they construction a framework of understanding of abstract concepts. The first activity is designed to introduce the concept of a three-component seismogram and to directly address the very abstract nature of seismograms through a kinesthetic experience. Students first learn to take the pulse of their classroom through a guided exploration of SeisMac, which displays the output of the laptop's built-in Sudden Motion Sensor (a 3-component accelerometer). This exploration allows students to view a 3-component seismogram as they move or tap the laptop and encourages them to propose and carry out experiments to explain the meaning of the 3-component seismogram. Once completed students are then asked to apply this new knowledge to a real 3-component seismogram printed from REV. Next the activity guides students through the process of identifying P and S waves and using SeisMac to connect the physical motion of the laptop to the "wiggles" they see on the SeisMac display and then comparing those to the "wiggles" they see on their seismogram. At this point students are more fully prepared to engage in an S-P location exercise such as those included in many state standards

Performance of Irikura Recipe Rupture Model Generator in Earthquake Ground Motion Simulations with Graves and Pitarka Hybrid Approach

NASA Astrophysics Data System (ADS)

Pitarka, Arben; Graves, Robert; Irikura, Kojiro; Miyake, Hiroe; Rodgers, Arthur

2017-09-01

We analyzed the performance of the Irikura and Miyake (Pure and Applied Geophysics 168(2011):85-104, 2011) (IM2011) asperity-based kinematic rupture model generator, as implemented in the hybrid broadband ground motion simulation methodology of Graves and Pitarka (Bulletin of the Seismological Society of America 100(5A):2095-2123, 2010), for simulating ground motion from crustal earthquakes of intermediate size. The primary objective of our study is to investigate the transportability of IM2011 into the framework used by the Southern California Earthquake Center broadband simulation platform. In our analysis, we performed broadband (0-20 Hz) ground motion simulations for a suite of M6.7 crustal scenario earthquakes in a hard rock seismic velocity structure using rupture models produced with both IM2011 and the rupture generation method of Graves and Pitarka (Bulletin of the Seismological Society of America, 2016) (GP2016). The level of simulated ground motions for the two approaches compare favorably with median estimates obtained from the 2014 Next Generation Attenuation-West2 Project (NGA-West2) ground motion prediction equations (GMPEs) over the frequency band 0.1-10 Hz and for distances out to 22 km from the fault. We also found that, compared to GP2016, IM2011 generates ground motion with larger variability, particularly at near-fault distances (<12 km) and at long periods (>1 s). For this specific scenario, the largest systematic difference in ground motion level for the two approaches occurs in the period band 1-3 s where the IM2011 motions are about 20-30% lower than those for GP2016. We found that increasing the rupture speed by 20% on the asperities in IM2011 produced ground motions in the 1-3 s bandwidth that are in much closer agreement with the GMPE medians and similar to those obtained with GP2016. The potential implications of this modification for other rupture mechanisms and magnitudes are not yet fully understood, and this topic is the subject of

Correlations between ground motion and building damage. Engineering intensity scale applied to the San Fernando earthquake of February 1971

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hafen, D.; Kintzer, F.C.

1977-11-01

The correlation between ground motion and building damage was investigated for the San Fernando earthquake of 1971. A series of iso-intensity maps was compiled to summarize the ground motion in terms of the Blume Engineering Intensity Scale (EIS). This involved the analysis of ground motion records from 62 stations in the Los Angeles area. Damage information for low-rise buildings was obtained in the form of records of loans granted by the Small Business Administration to repair earthquake damage. High-rise damage evaluations were based on direct inquiry and building inspection. Damage factors (ratio of damage repair cost to building value) weremore » calculated and summarized on contour maps. A statistical study was then undertaken to determine relationships between ground motion and damage factor. Several parameters for ground motion were considered and evaluated by means of correlation coefficients.« less

Evaluation of ground deformations induced by the 1999 Kocaeli earthquake (Turkey) at selected sites on shorelines

NASA Astrophysics Data System (ADS)

Aydan, Ömer; Ulusay, Reşat; Atak, Veysel Okan

2008-03-01

The Kocaeli earthquake ( M w = 7.4) of 17 August 1999 occurred in the Eastern Marmara Region of Turkey along the North Anadolu Fault and resulted in a very serious loss of life and property. One of the most important geotechnical issues of this event was the permanent ground deformations because of both liquefaction and faulting. These deformations occurred particularly along the southern shores of İzmit Bay and Sapanca Lake between the cities of Yalova and Adapazarı in the west and east, respectively. In this study, three sites founded on delta fans, namely Değirmendere Nose, Yeniköy tea garden at Seymen on the coast of İzmit Bay, and Vakıf Hotel site on the coast of Sapanca Lake were selected as typical cases. The main causes of the ground deformations at these sites were then investigated. Geotechnical characterization of the ground, derivation of displacement vectors from the pre- and post-earthquake aerial photographs, liquefaction assessments based on field performance data, and analyses carried out using the sliding body method have been fundamental in this study. The displacement vectors determined from photogrammetric evaluations conducted at Değirmendere and Seymen showed a combined movement of faulting and liquefaction. But except the movements in the close vicinity of shorelines, the dominant factor in this movement was faulting. The results obtained from the analyses suggested that the ground failure at Değirmendere was a submarine landslide mainly because of earthquake shaking rather than liquefaction. On the other hand, the ground failures at the Yeniköy tea garden on the coast of Seymen and the hotel area in Sapanca town resulted from liquefaction-induced lateral spreading. It was also obtained that the ground deformations estimated from the sliding body method were quite close to those measured by aerial photogrammetry technique.

Seismic Study of Tremor, Deep Long-Period Earthquakes, and Basin Amplification of Ground Motion

NASA Astrophysics Data System (ADS)

Han, Jiangang

In this thesis, we use seismic data and seismological tools to investigate three topics, (1) triggering between slow slip (tremor as proxy) and nearby small earthquakes, (2) mechanisms of deep-long period earthquakes beneath Mount St. Helens, and (3) ground motion amplification in Seattle Basin. In Chapter 1, we investigate 12-year earthquake and tremor catalogs for southwest Japan, and find nearby small intraslab earthquakes are weakly correlated with tremor. In particular, intraslab earthquakes tend to be followed by tremor more often than expected at random, while the excess number of tremor before earthquakes is not as significant. The underlying triggering mechanism of tremor and inferred slow slip by earthquakes is most likely to be the dynamic stress changes (several to several tens of kPa) rather than the much smaller static stress changes. In Chapter 2, we use the catalog DLPs as templates to search for repeating events at Mount St. Helens (MSH). We have detected 277 DLPs, compared to only 22 events previously in the catalog from 2007 to 2016. Three templates from the catalog are single events, while all other templates produced matches, identifying loci of repeated activity. Overall, the detected DLPs show no significant correlation with either the subduction zone tremor and slow slip (ETS) west of MSH, or the shallow seismicity. Temporal analysis shows an elevated rate of DLPs at time of compressional tidal stress, suggesting their possible association with magmatic and/or fluid activity. We observed variable S wave polarization of the DLPs from the most productive DLP source region, indicating their source mechanisms are not identical. In Chapter 3, we use noise correlation to retrieve the empirical green's functions (EGFs) in Seattle Basin. Consistent amplitudes measured from noise EGFs, teleseismic S wave and numerical simulations all suggest the usefulness of the amplitude of EGFs. For surface wave with period of 5-10 sec propagating from west to

Preliminary results of strong ground motion simulation for the Lushan earthquake of 20 April 2013, China

NASA Astrophysics Data System (ADS)

Zhu, Gengshang; Zhang, Zhenguo; Wen, Jian; Zhang, Wei; Chen, Xiaofei

2013-08-01

The earthquake occurred in Lushan County on 20 April, 2013 caused heavy casualty and economic loss. In order to understand how the seismic energy propagates during this earthquake and how it causes the seismic hazard, we simulated the strong ground motions from a representative kinematic source model by Zhang et al. (Chin J Geophys 56(4):1408-1411, 2013) for this earthquake. To include the topographic effects, we used the curved grids finite difference method by Zhang and Chen (Geophys J Int 167(1):337-353, 2006), Zhang et al. (Geophys J Int 190(1):358-378, 2012) to implement the simulations. Our results indicated that the majority of seismic energy concentrated in the epicentral area and the vicinal Sichuan Basin, causing the XI and VII degree intensity. Due to the strong topographic effects of the mountain, the seismic intensity in the border area across the northeastern of Boxing County to the Lushan County also reached IX degree. Moreover, the strong influence of topography caused the amplifications of ground shaking at the mountain ridge, which is easy to cause landslides. These results are quite similar to those observed in the Wenchuan earthquake of 2008 occurred also in a strong topographic mountain area.

Response of Olive View Hospital to Northridge and Whittier earthquakes

USGS Publications Warehouse

Celebi, M.

1997-01-01

The purpose of this paper is to study the response of the conventionally designed new Olive View Medical Center (OVMC) building at 16 km from the epicenter of the January 17, 1994 Northridge, California earthquake (Ms = 6.8). OVMC is on an alluvial deposit. The building was subjected to design level peak accelerations during the earthquake and suffered only limited structural and nonstructural damage. The recorded motions at different levels of the OVMC building as well as its associated free-field sites are analyzed using spectral analyses and system identification techniques. The new OVMC building was conservatively designed in 1976 with very high lateral load resisting capability - particularly as a reaction to the detrimental fate of the original Olive View Hospital that was heavily damaged during the 1971 San Fernando earthquake. The original hospital building was later razed. The replacement structure, the new cross-shaped OVMC building, experienced peak acceleration of 2.31g at the roof while its peak ground floor acceleration was 0.82g. The free-field peak acceleration was 0.91g. The lateral load resisting system of the OVMC building consists of concrete shear walls in the lower two stories and steel shear walls at the perimeter of the upper four stories. Spectral analysis shows that this stiff structure was not affected by the long duration pulses of the motions recorded at this site.

Earthquake Hazard Analysis Use Vs30 Data In Palu

NASA Astrophysics Data System (ADS)

Rusydi, Muhammad; Efendi, Rustan; Sandra; Rahmawati

2018-03-01

Palu City is an area passed by Palu-Koro fault and some small faults around it, causing the Palu of city often hit by earthquake. Therefore, this study is intended to mapped the earthquake hazard zones. Determination of this zone is one of aspect that can be used to reducing risk of earthquake disaster. This research was conducted by integrating Vs30 data from USGS with Vs30 from mikrotremor data. Vs30 data from microtremor used to correction Vs30 from USGS. This Results are then used to determine PeakGround Acceleration (PGA) can be used to calculate the impact of earthquake disaster. Results of the study shows that Palu City is in high danger class. Eight sub-districts in Palu City, there are 7 sub-districts that have high danger level, namely Palu Barat, PaluTimur, Palu Selatan, Palu Utara, Tatanga, Mantikulore and Tawaeli.

TriNet "ShakeMaps": Rapid generation of peak ground motion and intensity maps for earthquakes in southern California

USGS Publications Warehouse

Wald, D.J.; Quitoriano, V.; Heaton, T.H.; Kanamori, H.; Scrivner, C.W.; Worden, C.B.

1999-01-01

Rapid (3-5 minutes) generation of maps of instrumental ground-motion and shaking intensity is accomplished through advances in real-time seismographic data acquisition combined with newly developed relationships between recorded ground-motion parameters and expected shaking intensity values. Estimation of shaking over the entire regional extent of southern California is obtained by the spatial interpolation of the measured ground motions with geologically based frequency and amplitude-dependent site corrections. Production of the maps is automatic, triggered by any significant earthquake in southern California. Maps are now made available within several minutes of the earthquake for public and scientific consumption via the World Wide Web; they will be made available with dedicated communications for emergency response agencies and critical users.

Ground-rupturing earthquakes on the northern Big Bend of the San Andreas Fault, California, 800 A.D. to Present

USGS Publications Warehouse

Scharer, Katherine M.; Weldon, Ray; Biasi, Glenn; Streig, Ashley; Fumal, Thomas E.

2017-01-01

Paleoseismic data on the timing of ground-rupturing earthquakes constrain the recurrence behavior of active faults and can provide insight on the rupture history of a fault if earthquakes dated at neighboring sites overlap in age and are considered correlative. This study presents the evidence and ages for 11 earthquakes that occurred along the Big Bend section of the southern San Andreas Fault at the Frazier Mountain paleoseismic site. The most recent earthquake to rupture the site was the Mw7.7–7.9 Fort Tejon earthquake of 1857. We use over 30 trench excavations to document the structural and sedimentological evolution of a small pull-apart basin that has been repeatedly faulted and folded by ground-rupturing earthquakes. A sedimentation rate of 0.4 cm/yr and abundant organic material for radiocarbon dating contribute to a record that is considered complete since 800 A.D. and includes 10 paleoearthquakes. Earthquakes have ruptured this location on average every ~100 years over the last 1200 years, but individual intervals range from ~22 to 186 years. The coefficient of variation of the length of time between earthquakes (0.7) indicates quasiperiodic behavior, similar to other sites along the southern San Andreas Fault. Comparison with the earthquake chronology at neighboring sites along the fault indicates that only one other 1857-size earthquake could have occurred since 1350 A.D., and since 800 A.D., the Big Bend and Mojave sections have ruptured together at most 50% of the time in Mw ≥ 7.3 earthquakes.

Point-source stochastic-method simulations of ground motions for the PEER NGA-East Project

USGS Publications Warehouse

Boore, David

2015-01-01

Ground-motions for the PEER NGA-East project were simulated using a point-source stochastic method. The simulated motions are provided for distances between of 0 and 1200 km, M from 4 to 8, and 25 ground-motion intensity measures: peak ground velocity (PGV), peak ground acceleration (PGA), and 5%-damped pseudoabsolute response spectral acceleration (PSA) for 23 periods ranging from 0.01 s to 10.0 s. Tables of motions are provided for each of six attenuation models. The attenuation-model-dependent stress parameters used in the stochastic-method simulations were derived from inversion of PSA data from eight earthquakes in eastern North America.

The August 2011 Virginia and Colorado Earthquake Sequences: Does Stress Drop Depend on Strain Rate?

NASA Astrophysics Data System (ADS)

Abercrombie, R. E.; Viegas, G.

2011-12-01

Our preliminary analysis of the August 2011 Virginia earthquake sequence finds the earthquakes to have high stress drops, similar to those of recent earthquakes in NE USA, while those of the August 2011 Trinidad, Colorado, earthquakes are moderate - in between those typical of interplate (California) and the east coast. These earthquakes provide an unprecedented opportunity to study such source differences in detail, and hence improve our estimates of seismic hazard. Previously, the lack of well-recorded earthquakes in the eastern USA severely limited our resolution of the source processes and hence the expected ground accelerations. Our preliminary findings are consistent with the idea that earthquake faults strengthen during longer recurrence times and intraplate faults fail at higher stress (and produce higher ground accelerations) than their interplate counterparts. We use the empirical Green's function (EGF) method to calculate source parameters for the Virginia mainshock and three larger aftershocks, and for the Trinidad mainshock and two larger foreshocks using IRIS-available stations. We select time windows around the direct P and S waves at the closest stations and calculate spectral ratios and source time functions using the multi-taper spectral approach (eg. Viegas et al., JGR 2010). Our preliminary results show that the Virginia sequence has high stress drops (~100-200 MPa, using Madariaga (1976) model), and the Colorado sequence has moderate stress drops (~20 MPa). These numbers are consistent with previous work in the regions, for example the Au Sable Forks (2002) earthquake, and the 2010 Germantown (MD) earthquake. We also calculate the radiated seismic energy and find the energy/moment ratio to be high for the Virginia earthquakes, and moderate for the Colorado sequence. We observe no evidence of a breakdown in constant stress drop scaling in this limited number of earthquakes. We extend our analysis to a larger number of earthquakes and stations

Near-fault peak ground velocity from earthquake and laboratory data

USGS Publications Warehouse

McGarr, A.; Fletcher, Joe B.

2007-01-01

We test the hypothesis that peak ground velocity (PGV) has an upper bound independent of earthquake magnitude and that this bound is controlled primarily by the strength of the seismogenic crust. The highest PGVs, ranging up to several meters per second, have been measured at sites within a few kilometers of the causative faults. Because the database for near-fault PGV is small, we use earthquake slip models, laboratory experiments, and evidence from a mining-induced earthquake to investigate the factors influencing near-fault PGV and the nature of its scaling. For each earthquake slip model we have calculated the peak slip rates for all subfaults and then chosen the maximum of these rates as an estimate of twice the largest near-fault PGV. Nine slip models for eight earthquakes, with magnitudes ranging from 6.5 to 7.6, yielded maximum peak slip rates ranging from 2.3 to 12 m/sec with a median of 5.9 m/sec. By making several adjustments, PGVs for small earthquakes can be simulated from peak slip rates measured during laboratory stick-slip experiments. First, we adjust the PGV for differences in the state of stress (i.e., the difference between the laboratory loading stresses and those appropriate for faults at seismogenic depths). To do this, we multiply both the slip and the peak slip rate by the ratio of the effective normal stresses acting on fault planes measured at 6.8 km depth at the KTB site, Germany (deepest available in situ stress measurements), to those acting on the laboratory faults. We also adjust the seismic moment by replacing the laboratory fault with a buried circular shear crack whose radius is chosen to match the experimental unloading stiffness. An additional, less important adjustment is needed for experiments run in triaxial loading conditions. With these adjustments, peak slip rates for 10 stick-slip events, with scaled moment magnitudes from -2.9 to 1.0, range from 3.3 to 10.3 m/sec, with a median of 5.4 m/sec. Both the earthquake and

Seismo-induced effects in the near-earth space: Combined ground and space investigations as a contribution to earthquake prediction

NASA Astrophysics Data System (ADS)

Sgrigna, V.; Buzzi, A.; Conti, L.; Picozza, P.; Stagni, C.; Zilpimiani, D.

2007-02-01

The paper aims at giving a few methodological suggestions in deterministic earthquake prediction studies based on combined ground-based and space observations of earthquake precursors. Up to now what is lacking is the demonstration of a causal relationship with explained physical processes and looking for a correlation between data gathered simultaneously and continuously by space observations and ground-based measurements. Coordinated space and ground-based observations imply available test sites on the Earth surface to correlate ground data, collected by appropriate networks of instruments, with space ones detected on board of LEO satellites. At this purpose a new result reported in the paper is an original and specific space mission project (ESPERIA) and two instruments of its payload. The ESPERIA space project has been performed for the Italian Space Agency and three ESPERIA instruments (ARINA and LAZIO particle detectors, and EGLE search-coil magnetometer) have been built and tested in space. The EGLE experiment started last April 15, 2005 on board the ISS, within the ENEIDE mission. The launch of ARINA occurred on June 15, 2006, on board the RESURS DK-1 Russian LEO satellite. As an introduction and justification to these experiments the paper clarifies some basic concepts and critical methodological aspects concerning deterministic and statistic approaches and their use in earthquake prediction. We also take the liberty of giving the scientific community a few critical hints based on our personal experience in the field and propose a joint study devoted to earthquake prediction and warning.

Broadband simulations for Mw 7.8 southern san andreas earthquakes: Ground motion sensitivity to rupture speed

USGS Publications Warehouse

Graves, R.W.; Aagaard, Brad T.; Hudnut, K.W.; Star, L.M.; Stewart, J.P.; Jordan, T.H.

2008-01-01

Using the high-performance computing resources of the Southern California Earthquake Center, we simulate broadband (0-10 Hz) ground motions for three Mw 7.8 rupture scenarios of the southern San Andreas fault. The scenarios incorporate a kinematic rupture description with the average rupture speed along the large slip portions of the fault set at 0.96, 0.89, and 0.84 times the local shear wave velocity. Consistent with previous simulations, a southern hypocenter efficiently channels energy into the Los Angeles region along the string of basins south of the San Gabriel Mountains. However, we find the basin ground motion levels are quite sensitive to the prescribed rupture speed, with peak ground velocities at some sites varying by over a factor of two for variations in average rupture speed of about 15%. These results have important implications for estimating seismic hazards in Southern California and emphasize the need for improved understanding of earthquake rupture processes. Copyright 2008 by the American Geophysical Union.

Ground motion observations of the 2014 South Napa earthquake

USGS Publications Warehouse

Baltay, Annemarie S.; Boatwright, John

2015-01-01

Using the ground‐motion data compiled and reported by ShakeMap (Wald et al., 2000), we examine the peak ground acceleration (PGA) and peak ground velocity (PGV), as well as the pseudospectral acceleration (PSA) at periods of 0.3, 1.0, and 3.0 s. At the higher frequencies, especially PGA, data recorded at close distances (within ∼20  km) are very consistent with the GMPEs, implying a stress drop for this event similar to the median for California, that is, 5 MPa (Baltay and Hanks, 2014). At all frequencies, the attenuation with distance is stronger than the GMPEs would predict, which suggests the attenuation in the Napa and San Francisco Bay delta region is stronger than the average attenuation in California. The spatial plot of the ground‐motion residuals is positive to the north, in both Napa and Sonoma Valleys, consistent with increases in amplitude expected from both the directivity and basin effects. More interestingly, perhaps, there is strong ground motion to the south in the along‐strike direction, particularly for PSA at 1.0 s. These strongly positive residuals align with an older, Quaternary fault structure associated with the Franklin or Southampton fault, potentially indicating a fault‐zone‐guided wave.

Ground motion models used in the 2014 U.S. National Seismic Hazard Maps

USGS Publications Warehouse

Rezaeian, Sanaz; Petersen, Mark D.; Moschetti, Morgan P.

2015-01-01

The National Seismic Hazard Maps (NSHMs) are an important component of seismic design regulations in the United States. This paper compares hazard using the new suite of ground motion models (GMMs) relative to hazard using the suite of GMMs applied in the previous version of the maps. The new source characterization models are used for both cases. A previous paper (Rezaeian et al. 2014) discussed the five NGA-West2 GMMs used for shallow crustal earthquakes in the Western United States (WUS), which are also summarized here. Our focus in this paper is on GMMs for earthquakes in stable continental regions in the Central and Eastern United States (CEUS), as well as subduction interface and deep intraslab earthquakes. We consider building code hazard levels for peak ground acceleration (PGA), 0.2-s, and 1.0-s spectral accelerations (SAs) on uniform firm-rock site conditions. The GMM modifications in the updated version of the maps created changes in hazard within 5% to 20% in WUS; decreases within 5% to 20% in CEUS; changes within 5% to 15% for subduction interface earthquakes; and changes involving decreases of up to 50% and increases of up to 30% for deep intraslab earthquakes for most U.S. sites. These modifications were combined with changes resulting from modifications in the source characterization models to obtain the new hazard maps.

Liquefaction, ground oscillation, and soil deformation at the Wildlife Array, California

USGS Publications Warehouse

Holzer, T.L.; Youd, T.L.

2007-01-01

Excess pore-water pressure and liquefaction at the Wildlife Liquefaction Array in 1987 were caused by deformation associated with both high-frequency strong ground motion and 5.5-second-period Love waves. The Love waves produced large (???1.5%) cyclic shear strains well after the stronger high-frequency ground motion abated. These cyclic strains generated approximately from 13 to 35% of the excess pore-water pressure in the liquefied layer and caused excess pore-water pressures ultimately to reach effective overburden stress. The deformation associated with the Love waves explains the "postearthquake" increase of pore-water pressure that was recorded at the array. This explanation suggests that conventional methods for predicting liquefaction based on peak ground acceleration are incomplete and may need to consider cyclic strains associated with long-period surface waves. A post-earthquake survey of an inclinometer casing indicated permanent shear strain associated with lateral spreading primarily occurred in the upper part of the liquefied layer. Comparison of cone penetration test soundings conducted after the earthquake with pre-earthquake soundings suggests sleeve friction increased. Natural lateral variability of the liquefied layer obscured changes in tip resistance despite a ???1% reduction in volume. The large oscillatory motion associated with surface waves explains ground oscillation that has been reported at some liquefaction sites during earthquakes.

Empirical development of ground acceleration, velocity, and displacement for accidental explosions at J5 or the proposed large altitude rocket cell at Arnold Engineering Development Center

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davis, B.C.

This study is an assessment of the ground shock which may be generated in the event of an accidental explosion at J5 or the Proposed Large Altitude Rocket Cell (LARC) at the Arnold Engineering Development Center (AEDC). The assessment is accomplished by reviewing existing empirical relationships for predicting ground motion from ground shock. These relationships are compared with data for surface explosions at sites with similar geology and with yields similar to expected conditions at AEDC. Empirical relationships are developed from these data and a judgment made whether to use existing empirical relationships or the relationships developed in this study.more » An existing relationship (Lipner et al.) is used to predict velocity; the empirical relationships developed in the course of this study are used to predict acceleration and displacement. The ground motions are presented in table form and as contour plots. Included also is a discussion of damage criteria from blast and earthquake studies. This report recommends using velocity rather than acceleration as an indicator of structural blast damage. It is recommended that v = 2 ips (v = .167 fps) be used as the damage threshold value (no major damage for v less than or equal to 2 ips). 13 references, 25 figures, 6 tables.« less

Strong nonlinear dependence of the spectral amplification factors of deep Vrancea earthquakes magnitude

NASA Astrophysics Data System (ADS)

Marmureanu, Gheorghe; Ortanza Cioflan, Carmen; Marmureanu, Alexandru

2010-05-01

Nonlinear effects in ground motion during large earthquakes have long been a controversial issue between seismologists and geotechnical engineers. Aki wrote in 1993:"Nonlinear amplification at sediments sites appears to be more pervasive than seismologists used to think…Any attempt at seismic zonation must take into account the local site condition and this nonlinear amplification( Local site effects on weak and strong ground motion, Tectonophysics,218,93-111). In other words, the seismological detection of the nonlinear site effects requires a simultaneous understanding of the effects of earthquake source, propagation path and local geological site conditions. The difficulty for seismologists in demonstrating the nonlinear site effects has been due to the effect being overshadowed by the overall patterns of shock generation and path propagation. The researchers from National Institute for Earth Physics ,in order to make quantitative evidence of large nonlinear effects, introduced the spectral amplification factor (SAF) as ratio between maximum spectral absolute acceleration (Sa), relative velocity (Sv) , relative displacement (Sd) from response spectra for a fraction of critical damping at fundamental period and peak values of acceleration(a-max),velocity (v-max) and displacement (d-max),respectively, from processed strong motion record and pointed out that there is a strong nonlinear dependence on earthquake magnitude and site conditions.The spectral amplification factors(SAF) are finally computed for absolute accelerations at 5% fraction of critical damping (β=5%) in five seismic stations: Bucharest-INCERC(soft soils, quaternary layers with a total thickness of 800 m);Bucharest-Magurele (dense sand and loess on 350m); Cernavoda Nuclear Power Plant site (marl, loess, limestone on 270 m) Bacau(gravel and loess on 20m) and Iassy (loess, sand, clay, gravel on 60 m) for last strong and deep Vrancea earthquakes: March 4,1977 (MGR =7.2 and h=95 km);August 30

Geomorphic and Geologic Controls of Geohazards induced by Nepal's 2015 Gorkha Earthquake

NASA Technical Reports Server (NTRS)

Kargel, J. S.; Leonard, G. J.; Shugar, D. H.; Haritashya, U.K.; Bevington, A.; Fielding, E. J.; Fujita, K.; Geertsema, M.; Miles, E. S.; Steiner, J.;

Source parameters of the 2013, Ms 7.0, Lushan earthquake and the characteristics of the near-fault strong ground motion

NASA Astrophysics Data System (ADS)

Zhao, Fengfan; Meng, Lingyuan

2016-04-01

The April 20, 2013 Ms 7.0, earthquake in Lushan city, Sichuan province of China occurred as the result of east-west oriented reverse-type motion on a north-south striking fault. The source location suggests the event occurred on the Southern part of Longmenshan fault at a depth of 13km. The maximum intensity is up to VIII to IX at Boxing and Lushan city, which are located in the meizoseismal area. In this study, we analyzed the dynamic source process with the source mechanism and empirical relationships, estimated the strong ground motion in the near-fault field based on the Brune's circle model. A dynamical composite source model (DCSM) has been developed to simulate the near-fault strong ground motion with associated fault rupture properties at Boxing and Lushan city, respectively. The results indicate that the frictional undershoot behavior in the dynamic source process of Lushan earthquake, which is actually different from the overshoot activity of the Wenchuan earthquake. Moreover, we discussed the characteristics of the strong ground motion in the near-fault field, that the broadband synthetic seismogram ground motion predictions for Boxing and Lushan city produced larger peak values, shorter durations and higher frequency contents. It indicates that the factors in near-fault strong ground motion was under the influence of higher effect stress drop and asperity slip distributions on the fault plane. This work is financially supported by the Natural Science Foundation of China (Grant No. 41404045) and by Science for Earthquake Resilience of CEA (XH14055Y).

Performance of Irikura recipe rupture model generator in earthquake ground motion simulations with Graves and Pitarka hybrid approach

USGS Publications Warehouse

Pitarka, Arben; Graves, Robert; Irikura, Kojiro; Miyake, Hiroe; Rodgers, Arthur

2017-01-01

We analyzed the performance of the Irikura and Miyake (Pure and Applied Geophysics 168(2011):85–104, 2011) (IM2011) asperity-based kinematic rupture model generator, as implemented in the hybrid broadband ground motion simulation methodology of Graves and Pitarka (Bulletin of the Seismological Society of America 100(5A):2095–2123, 2010), for simulating ground motion from crustal earthquakes of intermediate size. The primary objective of our study is to investigate the transportability of IM2011 into the framework used by the Southern California Earthquake Center broadband simulation platform. In our analysis, we performed broadband (0–20 Hz) ground motion simulations for a suite of M6.7 crustal scenario earthquakes in a hard rock seismic velocity structure using rupture models produced with both IM2011 and the rupture generation method of Graves and Pitarka (Bulletin of the Seismological Society of America, 2016) (GP2016). The level of simulated ground motions for the two approaches compare favorably with median estimates obtained from the 2014 Next Generation Attenuation-West2 Project (NGA-West2) ground motion prediction equations (GMPEs) over the frequency band 0.1–10 Hz and for distances out to 22 km from the fault. We also found that, compared to GP2016, IM2011 generates ground motion with larger variability, particularly at near-fault distances (<12 km) and at long periods (>1 s). For this specific scenario, the largest systematic difference in ground motion level for the two approaches occurs in the period band 1–3 s where the IM2011 motions are about 20–30% lower than those for GP2016. We found that increasing the rupture speed by 20% on the asperities in IM2011 produced ground motions in the 1–3 s bandwidth that are in much closer agreement with the GMPE medians and similar to those obtained with GP2016. The potential implications of this modification for other rupture mechanisms and magnitudes are not yet fully understood, and this topic is

The role of complex site and basin response in Wellington city, New Zealand, during the 2016 Mw 7.8 Kaikōura earthquake and other recent earthquake sequences.

NASA Astrophysics Data System (ADS)

Kaiser, A. E.; McVerry, G.; Wotherspoon, L.; Bradley, B.; Gerstenberger, M.; Benites, R. A.; Bruce, Z.; Bourguignon, S.; Giallini, S.; Hill, M.

2017-12-01

We present analysis of ground motion and complex amplification characteristics in Wellington during recent earthquake sequences and an overview of the 3D basin characterization and ongoing work to update site parameters for seismic design. Significant damage was observed in central Wellington, New Zealand's capital city, following the 2016 Mw7.8 Kaikōura earthquake. Damage was concentrated in mid-rise structures (5 - 15 storeys) and was clearly exacerbated by the particular characteristics of ground motion and the presence of basin effects. Due to the distance of the source (50 - 60km) from the central city, peak ground accelerations were moderate (up to 0.28g) and well within ultimate limit state (ULS) design levels. However, spectral accelerations within the 1 -2 s period range, exceeded 1 in 500 year design level spectra (ULS) in deeper parts of the basin. Amplification with respect to rock at these locations reached factors of up to 7, and was also observed with factors up to at least three across all central city soil recording sites. The ground motions in Wellington were the strongest recorded in the modern era of instrumentation. While similar amplification was observed during the 2013 Mw 6.6 Cook Strait and Grassmere earthquakes, which struck close to the termination of the Kaikōura earthquake rupture, these sources were not sufficiently large to excite significant long-period motions. However, other M7.2+ sources in the region that dominate the seismic hazard, e.g. Wellington Fault, Hikurangi subduction interface and other large proximal crustal faults, are also potentially capable of exciting significant long-period basin response in Wellington. These observations and the expectation of ongoing heightened seismicity have prompted re-evaluation of the current seismic demand levels. Additional field campaigns have also been undertaken to update geotechnical properties and the 3D basin model, in order to inform ongoing research and seismic design practice.

Scaling earthquake ground motions for performance-based assessment of buildings

USGS Publications Warehouse

Huang, Y.-N.; Whittaker, A.S.; Luco, N.; Hamburger, R.O.

2011-01-01

The impact of alternate ground-motion scaling procedures on the distribution of displacement responses in simplified structural systems is investigated. Recommendations are provided for selecting and scaling ground motions for performance-based assessment of buildings. Four scaling methods are studied, namely, (1)geometric-mean scaling of pairs of ground motions, (2)spectrum matching of ground motions, (3)first-mode-period scaling to a target spectral acceleration, and (4)scaling of ground motions per the distribution of spectral demands. Data were developed by nonlinear response-history analysis of a large family of nonlinear single degree-of-freedom (SDOF) oscillators that could represent fixed-base and base-isolated structures. The advantages and disadvantages of each scaling method are discussed. The relationship between spectral shape and a ground-motion randomness parameter, is presented. A scaling procedure that explicitly considers spectral shape is proposed. ?? 2011 American Society of Civil Engineers.

On the dependency of the decay of ground motion peak values with distance for small and large earthquakes

NASA Astrophysics Data System (ADS)

Dujardin, Alain; Courboulex, Françoise; Causse, Matthieu; Traversa, Paola; Monfret, Tony

2013-04-01

Ground motion decay with distance presents a clear magnitude dependence, PGA values of small events decreasing faster than those of larger events. This observation is now widely accepted and often taken into account in recent ground motion prediction equations (Anderson 2005, Akkar & Bommer 2010). The aim of this study is to investigate the origin of this dependence, which has not been clearly identified yet. Two main hypotheses are considered. On one hand the difference of ground motion decay is related to an attenuation effect, on the other hand the difference is related to an effect of extended fault (Anderson 2000). To study the role of attenuation, we realized synthetic tests using the stochastic simulation program SMSIM from Boore (2005). We build a set of simulations from several magnitudes and epicentral distances, and observe that the decay in PGA values is strongly dependent on the spectral shape of the Fourier spectra, which in turn strongly depends on the attenuation factor (Q(f) or kappa). We found that, for a point source approximation and an infinite value of Q (no attenuation) there is no difference between small and large events and that this difference increases when Q decreases. Theses results show that the influence of attenuation on spectral shape is different for earthquakes of different magnitude. In fact the influence of attenuation, which is more important at higher frequency, is larger for small earthquakes, whose Fourier acceleration spectrum has predominantly higher frequencies. We then study the effect of extended source using complete waveform simulations in a 1D model. We find that when the duration of the source time function increases, there is a larger probability to obtain large PGA values at equivalent distances. This effect could also play an important role in the PGA decay with magnitude and distance. Finally we compare these results with real datasets from the Japanese accelerometric network KIK-net.

An Atlas of ShakeMaps and population exposure catalog for earthquake loss modeling

USGS Publications Warehouse

Allen, T.I.; Wald, D.J.; Earle, P.S.; Marano, K.D.; Hotovec, A.J.; Lin, K.; Hearne, M.G.

2009-01-01

We present an Atlas of ShakeMaps and a catalog of human population exposures to moderate-to-strong ground shaking (EXPO-CAT) for recent historical earthquakes (1973-2007). The common purpose of the Atlas and exposure catalog is to calibrate earthquake loss models to be used in the US Geological Survey's Prompt Assessment of Global Earthquakes for Response (PAGER). The full ShakeMap Atlas currently comprises over 5,600 earthquakes from January 1973 through December 2007, with almost 500 of these maps constrained-to varying degrees-by instrumental ground motions, macroseismic intensity data, community internet intensity observations, and published earthquake rupture models. The catalog of human exposures is derived using current PAGER methodologies. Exposure to discrete levels of shaking intensity is obtained by correlating Atlas ShakeMaps with a global population database. Combining this population exposure dataset with historical earthquake loss data, such as PAGER-CAT, provides a useful resource for calibrating loss methodologies against a systematically-derived set of ShakeMap hazard outputs. We illustrate two example uses for EXPO-CAT; (1) simple objective ranking of country vulnerability to earthquakes, and; (2) the influence of time-of-day on earthquake mortality. In general, we observe that countries in similar geographic regions with similar construction practices tend to cluster spatially in terms of relative vulnerability. We also find little quantitative evidence to suggest that time-of-day is a significant factor in earthquake mortality. Moreover, earthquake mortality appears to be more systematically linked to the population exposed to severe ground shaking (Modified Mercalli Intensity VIII+). Finally, equipped with the full Atlas of ShakeMaps, we merge each of these maps and find the maximum estimated peak ground acceleration at any grid point in the world for the past 35 years. We subsequently compare this "composite ShakeMap" with existing global

Earthquake Ground Motion Selection

DOT National Transportation Integrated Search

2012-05-01

Nonlinear analyses of soils, structures, and soil-structure systems offer the potential for more accurate characterization of geotechnical and structural response under strong earthquake shaking. The increasing use of advanced performance-based desig...

Spatial earthquake hazard assessment of Evansville, Indiana

USGS Publications Warehouse

Rockaway, T.D.; Frost, J.D.; Eggert, D.L.; Luna, R.

1997-01-01

The earthquake hazard has been evaluated for a 150-square-kilometer area around Evansville, Indiana. GIS-QUAKE, a system that combines liquefaction and ground motion analysis routines with site-specific geological, geotechnical, and seismological information, was used for the analysis. The hazard potential was determined by using 586 SPT borings, 27 CPT sounding, 39 shear-wave velocity profiles and synthesized acceleration records for body-wave magnitude 6.5 and 7.3 mid-continental earthquakes, occurring at distances of 50 km and 250 km, respectively. The results of the GIS-QUAKE hazard analyses for Evansville identify areas with a high hazard potential that had not previously been identified in earthquake zonation studies. The Pigeon Creek area specifically is identified as having significant potential for liquefaction-induced damage. Damage as a result of ground motion amplification is determined to be a moderate concern throughout the area. Differences in the findings of this zonation study and previous work are attributed to the size and range of the database, the hazard evaluation methodologies, and the geostatistical interpolation techniques used to estimate the hazard potential. Further, assumptions regarding the groundwater elevations made in previous studies are also considered to have had a significant effect on the results.

A study of Guptkashi, Uttarakhand earthquake of 6 February 2017 ( M w 5.3) in the Himalayan arc and implications for ground motion estimation

NASA Astrophysics Data System (ADS)

Srinagesh, Davuluri; Singh, Shri Krishna; Suresh, Gaddale; Srinivas, Dakuri; Pérez-Campos, Xyoli; Suresh, Gudapati

2018-05-01

The 2017 Guptkashi earthquake occurred in a segment of the Himalayan arc with high potential for a strong earthquake in the near future. In this context, a careful analysis of the earthquake is important as it may shed light on source and ground motion characteristics during future earthquakes. Using the earthquake recording on a single broadband strong-motion seismograph installed at the epicenter, we estimate the earthquake's location (30.546° N, 79.063° E), depth ( H = 19 km), the seismic moment ( M 0 = 1.12×1017 Nm, M w 5.3), the focal mechanism ( φ = 280°, δ = 14°, λ = 84°), the source radius ( a = 1.3 km), and the static stress drop (Δ σ s 22 MPa). The event occurred just above the Main Himalayan Thrust. S-wave spectra of the earthquake at hard sites in the arc are well approximated (assuming ω -2 source model) by attenuation parameters Q( f) = 500 f 0.9, κ = 0.04 s, and f max = infinite, and a stress drop of Δ σ = 70 MPa. Observed and computed peak ground motions, using stochastic method along with parameters inferred from spectral analysis, agree well with each other. These attenuation parameters are also reasonable for the observed spectra and/or peak ground motion parameters in the arc at distances ≤ 200 km during five other earthquakes in the region (4.6 ≤ M w ≤ 6.9). The estimated stress drop of the six events ranges from 20 to 120 MPa. Our analysis suggests that attenuation parameters given above may be used for ground motion estimation at hard sites in the Himalayan arc via the stochastic method.

A study of Guptkashi, Uttarakhand earthquake of 6 February 2017 (M w 5.3) in the Himalayan arc and implications for ground motion estimation

NASA Astrophysics Data System (ADS)

Srinagesh, Davuluri; Singh, Shri Krishna; Suresh, Gaddale; Srinivas, Dakuri; Pérez-Campos, Xyoli; Suresh, Gudapati

2018-02-01

The 2017 Guptkashi earthquake occurred in a segment of the Himalayan arc with high potential for a strong earthquake in the near future. In this context, a careful analysis of the earthquake is important as it may shed light on source and ground motion characteristics during future earthquakes. Using the earthquake recording on a single broadband strong-motion seismograph installed at the epicenter, we estimate the earthquake's location (30.546° N, 79.063° E), depth (H = 19 km), the seismic moment (M 0 = 1.12×1017 Nm, M w 5.3), the focal mechanism (φ = 280°, δ = 14°, λ = 84°), the source radius (a = 1.3 km), and the static stress drop (Δσ s 22 MPa). The event occurred just above the Main Himalayan Thrust. S-wave spectra of the earthquake at hard sites in the arc are well approximated (assuming ω -2 source model) by attenuation parameters Q(f) = 500f 0.9, κ = 0.04 s, and f max = infinite, and a stress drop of Δσ = 70 MPa. Observed and computed peak ground motions, using stochastic method along with parameters inferred from spectral analysis, agree well with each other. These attenuation parameters are also reasonable for the observed spectra and/or peak ground motion parameters in the arc at distances ≤ 200 km during five other earthquakes in the region (4.6 ≤ M w ≤ 6.9). The estimated stress drop of the six events ranges from 20 to 120 MPa. Our analysis suggests that attenuation parameters given above may be used for ground motion estimation at hard sites in the Himalayan arc via the stochastic method.

Ground motions at the outermost limits of seismically triggered landslides

NASA Astrophysics Data System (ADS)

Jibson, Randall W.; Harp, Edwin L.

2016-04-01

Over the last few decades, we and our colleagues have conducted field investigations in which we mapped the outermost limits of triggered landslides in four earthquakes: 1987 Whittier Narrows, California (M 5.9), 1987 Superstition Hills, California (M 6.5), 1994 Northridge, California (M 6.7), and 2011 Mineral, Virginia (M 5.8). In an additional two earthquakes, 1976 Guatemala (M 7.5) and 1983 Coalinga, California (M 6.5), we determined limits using high-resolution aerial photographic interpretation in conjunction with more limited ground investigation. Limits in these earthquakes were defined by the locations of the very smallest failures (< 1 m^3) from the most susceptible slopes that can be identified positively as having been triggered by earthquake shaking. Because we and our colleagues conducted all of these investigations, consistent methodology and criteria were used in determining limits. In the six earthquakes examined, we correlated the outermost landslide limits with peak ground accelerations (PGA) from ShakeMap models of each earthquake. For the four earthquakes studied by field investigation, the minimum PGA values associated with farthest landslide limits ranged from 0.02-0.08 g. The range for the two earthquakes investigated using aerial photographic interpretations was 0.05-0.11 g. Although PGA values at landslide limits depend on several factors - including material strength, topographic amplification, and hydrologic conditions - these values provide an empirically useful lower limiting range of PGA needed to trigger the smallest failures on very susceptible slopes. In a well-recorded earthquake, this PGA range can be used to identify an outer boundary within which we might expect to find landsliding; in earthquakes that are not well recorded, mapping the outermost landslide limits provides a useful clue about ground-motion levels at the mapped limits.

Preliminary analysis of strong-motion recordings from the 28 September 2004 Parkfield, California earthquake

USGS Publications Warehouse

Shakal, A.; Graizer, V.; Huang, M.; Borcherdt, R.; Haddadi, H.; Lin, K.-W.; Stephens, C.; Roffers, P.

2005-01-01

The Parkfield 2004 earthquake yielded the most extensive set of strong-motion data in the near-source region of a magnitude 6 earthquake yet obtained. The recordings of acceleration and volumetric strain provide an unprecedented document of the near-source seismic radiation for a moderate earthquake. The spatial density of the measurements alon g the fault zone and in the linear arrays perpendicular to the fault is expected to provide an exceptional opportunity to develop improved models of the rupture process. The closely spaced measurements should help infer the temporal and spatial distribution of the rupture process at much higher resolution than previously possible. Preliminary analyses of the peak a cceleration data presented herein shows that the motions vary significantly along the rupture zone, from 0.13 g to more than 2.5 g, with a map of the values showing that the larger values are concentrated in three areas. Particle motions at the near-fault stations are consistent with bilateral rupture. Fault-normal pulses similar to those observed in recent strike-slip earthquakes are apparent at several of the stations. The attenuation of peak ground acceleration with distance is more rapid than that indicated by some standard relationships but adequately fits others. Evidence for directivity in the peak acceleration data is not strong. Several stations very near, or over, the rupturing fault recorded relatively low accelerations. These recordings may provide a quantitative basis to understand observations of low near-fault shaking damage that has been reported in other large strike-slip earthquak.

Strong Ground Motion Analysis and Afterslip Modeling of Earthquakes near Mendocino Triple Junction

NASA Astrophysics Data System (ADS)

Gong, J.; McGuire, J. J.

2017-12-01

The Mendocino Triple Junction (MTJ) is one of the most seismically active regions in North America in response to the ongoing motions between North America, Pacific and Gorda plates. Earthquakes near the MTJ come from multiple types of faults due to the interaction boundaries between the three plates and the strong internal deformation within them. Understanding the stress levels that drive the earthquake rupture on the various types of faults and estimating the locking state of the subduction interface are especially important for earthquake hazard assessment. However due to lack of direct offshore seismic and geodetic records, only a few earthquakes' rupture processes have been well studied and the locking state of the subducted slab is not well constrained. In this study we first use the second moment inversion method to study the rupture process of the January 28, 2015 Mw 5.7 strike slip earthquake on Mendocino transform fault using strong ground motion records from Cascadia Initiative community experiment as well as onshore seismic networks. We estimate the rupture dimension to be of 6 km by 3 km and a stress drop of 7 MPa on the transform fault. Next we investigate the frictional locking state on the subduction interface through afterslip simulation based on coseismic rupture models of this 2015 earthquake and a Mw 6.5 intraplate eathquake inside Gorda plate whose slip distribution is inverted using onshore geodetic network in previous study. Different depths for velocity strengthening frictional properties to start at the downdip of the locked zone are used to simulate afterslip scenarios and predict the corresponding surface deformation (GPS) movements onshore. Our simulations indicate that locking depth on the slab surface is at least 14 km, which confirms that the next M8 earthquake rupture will likely reach the coastline and strong shaking should be expected near the coast.

Ground motion in Anchorage, Alaska, from the 2002 Denali fault earthquake: Site response and Displacement Pulses

USGS Publications Warehouse

Boore, D.M.

2004-01-01

Data from the 2002 Denali fault earthquake recorded at 26 sites in and near Anchorage, Alaska, show a number of systematic features important in studies of site response and in constructing long-period spectra for use in earthquake engineering. The data demonstrate that National Earthquake Hazards Reduction Program (NEHRP) site classes are a useful way of grouping stations according to site amplification. In general, the sites underlain by lower shear-wave velocities have higher amplification. The amplification on NEHRP class D sites exceeds a factor of 2 relative to an average of motions on class C sites. The amplifications are period dependent. They are in rough agreement with those from previous studies, but the new data show that the amplifications extend to at least 10 sec, periods longer than considered in previous studies. At periods longer than about 14 sec, all sites have motion of similar amplitude, and the ground displacements are similar in shape, polarization, and amplitude for all stations. The displacement ground motion is dominated by a series of four pulses, which are associated with the three subevents identified in inversion studies (the first pulse is composed of P waves from the first subevent). Most of the high-frequency ground motion is associated with the S waves from subevent 1. The pulses from subevents 1 and 2, with moment releases corresponding to M 7.1 and 7.0, are similar to the pulse of displacement radiated by the M 7.1 Hector Mine earthquake. The signature from the largest subevent (M 7.6) is more subdued than those from the first two subevents. The two largest pulses produce response spectra with peaks at a period of about 15 sec. The spectral shape at long periods is in good agreement with the recent 2003 NEHRP code spectra but is in poor agreement with the shape obtained from Eurocode 8.

Report of Earthquake Drills with Experiences of Ground Motion in Childcare for Young Children, Japan

NASA Astrophysics Data System (ADS)

Yamada, N.

2013-12-01

After the Great East Japan Earthquake of 2011, this disaster has become one of the opportunities to raise awareness of earthquake and tsunami disaster prevention, and the improvement of disaster prevention education is to be emphasized. The influences of these bring the extension to the spatial axis in Japan, and also, it is important to make a development of the education with continuous to the expansion of time axes. Although fire or earthquake drills as the disaster prevention education are often found in Japan, the children and teachers only go from school building to outside. Besides, only the shortness of the time to spend for the drill often attracts attention. The complementary practice education by the cooperation with experts such as the firefighting is practiced, but the verification of the effects is not enough, and it is the present conditions that do not advance to the study either. Although it is expected that improvement and development of the disaster prevention educations are accomplished in future, there are a lot of the problems. Our target is construction and utilization of material contributing to the education about "During the strong motion" in case of the earthquake which may experience even if wherever of Japan. One of the our productions is the handicraft shaking table to utilize as teaching tools of the education to protect the body which is not hurt at the time of strong motion. This made much of simplicity than high reproduction of the earthquake ground motions. We aimed to helping the disaster prevention education including not only the education for young children but also for the school staff and their parents. In this report, the focusing on a way of the non-injured during the time of the earthquake ground motion, and adopting activity of the play, we are going to show the example of the framework of earthquake disaster prevention childcare through the virtual experience. This presentation has a discussion as a practice study with

Volcanic Eruption Forecasts From Accelerating Rates of Drumbeat Long-Period Earthquakes

NASA Astrophysics Data System (ADS)

Bell, Andrew F.; Naylor, Mark; Hernandez, Stephen; Main, Ian G.; Gaunt, H. Elizabeth; Mothes, Patricia; Ruiz, Mario

2018-02-01

Accelerating rates of quasiperiodic "drumbeat" long-period earthquakes (LPs) are commonly reported before eruptions at andesite and dacite volcanoes, and promise insights into the nature of fundamental preeruptive processes and improved eruption forecasts. Here we apply a new Bayesian Markov chain Monte Carlo gamma point process methodology to investigate an exceptionally well-developed sequence of drumbeat LPs preceding a recent large vulcanian explosion at Tungurahua volcano, Ecuador. For more than 24 hr, LP rates increased according to the inverse power law trend predicted by material failure theory, and with a retrospectively forecast failure time that agrees with the eruption onset within error. LPs resulted from repeated activation of a single characteristic source driven by accelerating loading, rather than a distributed failure process, showing that similar precursory trends can emerge from quite different underlying physics. Nevertheless, such sequences have clear potential for improving forecasts of eruptions at Tungurahua and analogous volcanoes.

Observations of seismicity and ground motion in the northeast U.S. Atlantic margin from ocean bottom seismometer data

USGS Publications Warehouse

Flores, Claudia; ten Brink, Uri S.; McGuire, Jeffrey J.; Collins, John A.

2017-01-01

Earthquake data from two short-period ocean-bottom seismometer (OBS) networks deployed for over a year on the continental slope off New York and southern New England were used to evaluate seismicity and ground motions along the continental margin. Our OBS networks located only one earthquake of Mc∼1.5 near the shelf edge during six months of recording, suggesting that seismic activity (MLg>3.0) of the margin as far as 150–200 km offshore is probably successfully monitored by land stations without the need for OBS deployments. The spectral acceleration from two local earthquakes recorded by the OBS was found to be generally similar to the acceleration from these earthquakes recorded at several seismic stations on land and to hybrid empirical acceleration relationships for eastern North America. Therefore, the seismic attenuation used for eastern North America can be extended in this region at least to the continental slope. However, additional offshore studies are needed to verify these preliminary conclusions.

Evaluating a kinematic method for generating broadband ground motions for great subduction zone earthquakes: Application to the 2003 Mw 8.3 Tokachi‐Oki earthquake

USGS Publications Warehouse

Wirth, Erin A.; Frankel, Arthur; Vidale, John E.

2017-01-01

We compare broadband synthetic seismograms with recordings of the 2003 Mw">MwMw 8.3 Tokachi‐Oki earthquake to evaluate a compound rupture model, in which slip on the fault consists of multiple high‐stress‐drop asperities superimposed on a background slip distribution with longer rise times. Low‐frequency synthetics (<1  Hz"><1  Hz<1  Hz) are calculated using deterministic, 3D finite‐difference simulations and are combined with high‐frequency (>1  Hz">>1  Hz>1  Hz) stochastic synthetics using a matched filter at 1 Hz. We show that this compound rupture model and overall approach accurately reproduces waveform envelopes and observed response spectral accelerations (SAs) from the Tokachi‐Oki event. We find that sufficiently short subfault rise times (i.e., <∼1–2  s"><∼1–2  s<∼1–2  s) are necessary to reproduce energy ∼1  Hz">∼1  Hz∼1  Hz. This is achieved by either (1) including distinct subevents with short rise times, as may be suggested by the Tokachi‐Oki data, or (2) imposing a fast‐slip velocity over the entire rupture area. We also include a systematic study on the effects of varying several kinematic rupture parameters. We find that simulated strong ground motions are sensitive to the average rupture velocity and coherence of the rupture front, with more coherent ruptures yielding higher response SAs. We also assess the effects of varying the average slip velocity and the character (i.e., area, magnitude, and location) of high‐stress‐drop subevents. Even in the absence of precise constraints on these kinematic rupture parameters, our simulations still reproduce major features in the Tokachi‐Oki earthquake data, supporting its accuracy in modeling future large earthquakes.

Validation of Atmosphere/Ionosphere Signals Associated with Major Earthquakes by Multi-Instrument Space-Borne and Ground Observations

NASA Technical Reports Server (NTRS)

Ouzounov, Dimitar; Pulinets, Sergey; Hattori, Katsumi; Parrot, Michel; Liu, J. Y.; Yang, T. F.; Arellano-Baeza, Alonso; Kafatos, M.; Taylor, Patrick

2012-01-01

regions of the atmosphere and the modifications, by dc electric fields, in the ionosphere-atmosphere electric circuit. We retrospectively analyzed temporal and spatial variations of four different physical parameters (gas/radon counting rate, lineaments change, long-wave radiation transitions and ionospheric electron density/plasma variations) characterizing the state of the lithosphere/atmosphere coupling several days before the onset of the earthquakes. Validation processes consist in two phases: A. Case studies for seven recent major earthquakes: Japan (M9.0, 2011), China (M7.9, 2008), Italy (M6.3, 2009), Samoa (M7, 2009), Haiti (M7.0, 2010) and, Chile (M8.8, 2010) and B. A continuous retrospective analysis was preformed over two different regions with high seismicity- Taiwan and Japan for 2003-2009. Satellite, ground surface, and troposphere data were obtained from Terra/ASTER, Aqua/AIRS, POES and ionospheric variations from DEMETER and COSMIC-I data. Radon and GPS/TEC were obtaining from monitoring sites in Taiwan, Japan and Italy and from global ionosphere maps (GIM) respectively. Our analysis of ground and satellite data during the occurrence of 7 global earthquakes has shown the presence of anomalies in the atmosphere. Our results for Tohoku M9.0 earthquake show that on March 7th, 2011 (4 days before the main shock and 1 day before the M7.2 foreshock of March 8, 2011) a rapid increase of emitted infrared radiation was observed by the satellite data and an anomaly was developed near the epicenter. The GPS/TEC data indicate an increase and variation in electron density reaching a maximum value on March 8. From March 3 to 11 a large increase in electron concentration was recorded at all four Japanese ground-based ionosondes, which returned to normal after the main earthquake. Similar approach for analyzing atmospheric and ionospheric parameters has been applied for China (M7.9, 2008), Italy (M6.3, 2009), Samoa (M7, 2009), Haiti (M7.0, 2010) and Chile (M8.8, 2010

Within-Event and Between-Events Ground Motion Variability from Earthquake Rupture Scenarios

NASA Astrophysics Data System (ADS)

Crempien, Jorge G. F.; Archuleta, Ralph J.

2017-09-01

Measurement of ground motion variability is essential to estimate seismic hazard. Over-estimation of variability can lead to extremely high annual hazard estimates of ground motion exceedance. We explore different parameters that affect the variability of ground motion such as the spatial correlations of kinematic rupture parameters on a finite fault and the corner frequency of the moment-rate spectra. To quantify the variability of ground motion, we simulate kinematic rupture scenarios on several vertical strike-slip faults and compute ground motion using the representation theorem. In particular, for the entire suite of rupture scenarios, we quantify the within-event and the between-events ground motion variability of peak ground acceleration (PGA) and response spectra at several periods, at 40 stations—all approximately at an equal distance of 20 and 50 km from the fault. Both within-event and between-events ground motion variability increase when the slip correlation length on the fault increases. The probability density functions of ground motion tend to truncate at a finite value when the correlation length of slip decreases on the fault, therefore, we do not observe any long-tail distribution of peak ground acceleration when performing several rupture simulations for small correlation lengths. Finally, for a correlation length of 6 km, the within-event and between-events PGA log-normal standard deviations are 0.58 and 0.19, respectively, values slightly smaller than those reported by Boore et al. (Earthq Spectra, 30(3):1057-1085, 2014). The between-events standard deviation is consistently smaller than the within-event for all correlations lengths, a feature that agrees with recent ground motion prediction equations.

Geomorphic and geologic controls of geohazards induced by Nepal's 2015 Gorkha earthquake.

PubMed

Kargel, J S; Leonard, G J; Shugar, D H; Haritashya, U K; Bevington, A; Fielding, E J; Fujita, K; Geertsema, M; Miles, E S; Steiner, J; Anderson, E; Bajracharya, S; Bawden, G W; Breashears, D F; Byers, A; Collins, B; Dhital, M R; Donnellan, A; Evans, T L; Geai, M L; Glasscoe, M T; Green, D; Gurung, D R; Heijenk, R; Hilborn, A; Hudnut, K; Huyck, C; Immerzeel, W W; Liming, Jiang; Jibson, R; Kääb, A; Khanal, N R; Kirschbaum, D; Kraaijenbrink, P D A; Lamsal, D; Shiyin, Liu; Mingyang, Lv; McKinney, D; Nahirnick, N K; Zhuotong, Nan; Ojha, S; Olsenholler, J; Painter, T H; Pleasants, M; Pratima, K C; Yuan, Q I; Raup, B H; Regmi, D; Rounce, D R; Sakai, A; Donghui, Shangguan; Shea, J M; Shrestha, A B; Shukla, A; Stumm, D; van der Kooij, M; Voss, K; Xin, Wang; Weihs, B; Wolfe, D; Lizong, Wu; Xiaojun, Yao; Yoder, M R; Young, N

2016-01-08

The Gorkha earthquake (magnitude 7.8) on 25 April 2015 and later aftershocks struck South Asia, killing ~9000 people and damaging a large region. Supported by a large campaign of responsive satellite data acquisitions over the earthquake disaster zone, our team undertook a satellite image survey of the earthquakes' induced geohazards in Nepal and China and an assessment of the geomorphic, tectonic, and lithologic controls on quake-induced landslides. Timely analysis and communication aided response and recovery and informed decision-makers. We mapped 4312 coseismic and postseismic landslides. We also surveyed 491 glacier lakes for earthquake damage but found only nine landslide-impacted lakes and no visible satellite evidence of outbursts. Landslide densities correlate with slope, peak ground acceleration, surface downdrop, and specific metamorphic lithologies and large plutonic intrusions. Copyright © 2016, American Association for the Advancement of Science.

Investigation on earthquake ground motions observed along a north-south survey line in the Kumamoto Plain, during the aftershocks of 2016 Kumamoto earthquake

NASA Astrophysics Data System (ADS)

Tsuno, S.; Korenaga, M.; Okamoto, K.; Chimoto, K.; Yamanaka, H.; Yamada, N.; Matsushima, T.

2017-12-01

To evaluate local site effects in the Kumamoto Plain, we installed 15 temporary seismic stations along the north-south survey line, after the 2016 Kumamoto earthquake foreshock (Mj 6.4). In this report, to investigate earthquake ground motions observed along the north-south survey line, we estimated site amplification factors from weak ground motion data and estimated S-wave velocity structures by array microtremor observations at temporary seismic stations. We installed 15 temporary seismic stations at an interval of 300m to 2.5km along the north-south survey line. We estimated site amplification factors, with a station at Mt. Kinbo as a reference. Site amplification factors at the middle part and the southern part along the survey line, located in the alluvial lowland, were dominated in the frequency of 1-2Hz. On the other hand, site amplification factors at the northern part along the survey line were dominated in the frequency of 2-5Hz. It suggests that the ground profiles near the surface are complicate along this north-south survey line in the Kumamoto Plain. Therefore, we performed array microtremor observations at the temporary seismic stations, to estimate S-wave velocity structures along the north-south survey line. We obtained phase velocities of Rayleigh waves by the SPAC method and estimated S-wave velocity structures by applying the Genetic Algorism to those phase velocity. The low velocity layer with a thickness of around 15m was deposited on the surface at sites located in the alluvial lowland. Finally, we compared the distribution of PGAs observed along the north-south survey line to AVs30 estimated by S-wave velocity structures. As a result, PGAs along the survey line were strongly concerned by AVs30. We concluded that earthquake ground motions in the frequency of more than 1Hz observed in this north-south survey line were excited by the low velocity layer near the surface.

Acceleration and volumetric strain generated by the Parkfield 2004 earthquake on the GEOS strong-motion array near Parkfield, California

USGS Publications Warehouse

Borcherdt, Rodger D.; Johnston, Malcolm J.S.; Dietel, Christopher; Glassmoyer, Gary; Myren, Doug; Stephens, Christopher

2004-01-01

An integrated array of 11 General Earthquake Observation System (GEOS) stations installed near Parkfield, CA provided on scale broad-band, wide-dynamic measurements of acceleration and volumetric strain of the Parkfield earthquake (M 6.0) of September 28, 2004. Three component measurements of acceleration were obtained at each of the stations. Measurements of collocated acceleration and volumetric strain were obtained at four of the stations. Measurements of velocity at most sites were on scale only for the initial P-wave arrival. When considered in the context of the extensive set of strong-motion recordings obtained on more than 40 analog stations by the California Strong-Motion Instrumentation Program (Shakal, et al., 2004 http://www.quake.ca.gov/cisn-edc) and those on the dense array of Spudich, et al, (1988), these recordings provide an unprecedented document of the nature of the near source strong motion generated by a M 6.0 earthquake. The data set reported herein provides the most extensive set of near field broad band wide dynamic range measurements of acceleration and volumetric strain for an earthquake as large as M 6 of which the authors are aware. As a result considerable interest has been expressed in these data. This report is intended to describe the data and facilitate its use to resolve a number of scientific and engineering questions concerning earthquake rupture processes and resultant near field motions and strains. This report provides a description of the array, its scientific objectives and the strong-motion recordings obtained of the main shock. The report provides copies of the uncorrected and corrected data. Copies of the inferred velocities, displacements, and Psuedo velocity response spectra are provided. Digital versions of these recordings are accessible with information available through the internet at several locations: the National Strong-Motion Program web site (http://agram.wr.usgs.gov/), the COSMOS Virtual Data Center Web site

Post earthquake recovery in natural gas systems--1971 San Fernando Earthquake

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, W.T. Jr.

1983-01-01

In this paper a concise summary of the post earthquake investigations for the 1971 San Fernando Earthquake is presented. The effects of the earthquake upon building and other above ground structures are briefly discussed. Then the damages and subsequent repairs in the natural gas systems are reported.

2001 Bhuj, India, earthquake engineering seismoscope recordings and Eastern North America ground-motion attenuation relations

USGS Publications Warehouse

Cramer, C.H.; Kumar, A.

2003-01-01

Engineering seismoscope data collected at distances less than 300 km for the M 7.7 Bhuj, India, mainshock are compatible with ground-motion attenuation in eastern North America (ENA). The mainshock ground-motion data have been corrected to a common geological site condition using the factors of Joyner and Boore (2000) and a classification scheme of Quaternary or Tertiary sediments or rock. We then compare these data to ENA ground-motion attenuation relations. Despite uncertainties in recording method, geological site corrections, common tectonic setting, and the amount of regional seismic attenuation, the corrected Bhuj dataset agrees with the collective predictions by ENA ground-motion attenuation relations within a factor of 2. This level of agreement is within the dataset uncertainties and the normal variance for recorded earthquake ground motions.

Seismic rupture and ground accelerations induced by CO 2 injection in the shallow crust

DOE PAGES

Cappa, Frédéric; Rutqvist, Jonny

2012-09-01

We present that because of the critically stressed nature of the upper crust, the injection of large volumes of carbon dioxide (CO 2) into shallow geological reservoirs can trigger seismicity and induce ground deformations when the injection increases the fluid pressure in the vicinity of potentially seismic faults. The increased fluid pressure reduces the strength against fault slip, allowing the stored elastic energy to be released in seismic events that can produce felt ground accelerations. Here, we seek to explore the likelihood ground motions induced by a CO 2 injection using hydromechanical modelling with multiphase fluid flow and dynamic rupture,more » including fault-frictional weakening. We extend the previous work of Cappa and Rutqvist, in which activation of a normal fault at critical stress may be possible for fast rupture nucleating by localized increase in fluid pressure and large decrease in fault friction. In this paper, we include seismic wave propagation generated by the rupture. For our assumed system and injection rate, simulations show that after a few days of injection, a dynamic fault rupture of few centimetres nucleates at the base of the CO 2 reservoir and grows bilaterally, both toward the top of the reservoir and outside. The rupture is asymmetric and affects a larger zone below the reservoir where the rupture is self-propagating (without any further pressure increase) as a result of fault-strength weakening. The acceleration and deceleration of the rupture generate waves and result in ground accelerations (~0.1–0.6 g) consistent with observed ground motion records. Finally, the maximum ground acceleration is obtained near the fault, and horizontal accelerations are generally markedly higher than vertical accelerations.« less

Use of Ground Motion Simulations of a Historical Earthquake for the Assessment of Past and Future Urban Risks

NASA Astrophysics Data System (ADS)

Kentel, E.; Çelik, A.; karimzadeh Naghshineh, S.; Askan, A.

2017-12-01

Erzincan city located in the Eastern part of Turkey at the conjunction of three active faults is one of the most hazardous regions in the world. In addition to several historical events, this city has experienced one of the largest earthquakes during the last century: The 27 December 1939 (Ms=8.0) event. With limited knowledge of the tectonic structure by then, the city center was relocated to the North after the 1939 earthquake by almost 5km, indeed closer to the existing major strike slip fault. This decision coupled with poor construction technologies, led to severe damage during a later event that occurred on 13 March 1992 (Mw=6.6). The 1939 earthquake occurred in the pre-instrumental era in the region with no available local seismograms whereas the 1992 event was only recorded by 3 nearby stations. There are empirical isoseismal maps from both events indicating indirectly the spatial distribution of the damage. In this study, we focus on this region and present a multidisciplinary approach to discuss the different components of uncertainties involved in the assessment and mitigation of seismic risk in urban areas. For this initial attempt, ground motion simulation of the 1939 event is performed to obtain the anticipated ground motions and shaking intensities. Using these quantified results along with the spatial distribution of the observed damage, the relocation decision is assessed and suggestions are provided for future large earthquakes to minimize potential earthquake risks.

Ground-motion prediction equations for the average horizontal component of PGA, PGV, and 5%-damped PSA at spectral periods between 0.01 s and 10.0 s

USGS Publications Warehouse

Boore, D.M.; Atkinson, G.M.

2008-01-01

This paper contains ground-motion prediction equations (GMPEs) for average horizontal-component ground motions as a function of earthquake magnitude, distance from source to site, local average shear-wave velocity, and fault type. Our equations are for peak ground acceleration (PGA), peak ground velocity (PGV), and 5%-damped pseudo-absolute-acceleration spectra (PSA) at periods between 0.01 s and 10 s. They were derived by empirical regression of an extensive strong-motion database compiled by the 'PEER NGA' (Pacific Earthquake Engineering Research Center's Next Generation Attenuation) project. For periods less than 1 s, the analysis used 1,574 records from 58 mainshocks in the distance range from 0 km to 400 km (the number of available data decreased as period increased). The primary predictor variables are moment magnitude (M), closest horizontal distance to the surface projection of the fault plane (RJB), and the time-averaged shear-wave velocity from the surface to 30 m (VS30). The equations are applicable for M=5-8, RJB<200 km, and VS30= 180-1300 m/s. ?? 2008, Earthquake Engineering Research Institute.

Discrepancy between earthquake rates implied by historic earthquakes and a consensus geologic source model for California

USGS Publications Warehouse

Petersen, M.D.; Cramer, C.H.; Reichle, M.S.; Frankel, A.D.; Hanks, T.C.

2000-01-01

We examine the difference between expected earthquake rates inferred from the historical earthquake catalog and the geologic data that was used to develop the consensus seismic source characterization for the state of California [California Department of Conservation, Division of Mines and Geology (CDMG) and U.S. Geological Survey (USGS) Petersen et al., 1996; Frankel et al., 1996]. On average the historic earthquake catalog and the seismic source model both indicate about one M 6 or greater earthquake per year in the state of California. However, the overall earthquake rates of earthquakes with magnitudes (M) between 6 and 7 in this seismic source model are higher, by at least a factor of 2, than the mean historic earthquake rates for both southern and northern California. The earthquake rate discrepancy results from a seismic source model that includes earthquakes with characteristic (maximum) magnitudes that are primarily between M 6.4 and 7.1. Many of these faults are interpreted to accommodate high strain rates from geologic and geodetic data but have not ruptured in large earthquakes during historic time. Our sensitivity study indicates that the rate differences between magnitudes 6 and 7 can be reduced by adjusting the magnitude-frequency distribution of the source model to reflect more characteristic behavior, by decreasing the moment rate available for seismogenic slip along faults, by increasing the maximum magnitude of the earthquake on a fault, or by decreasing the maximum magnitude of the background seismicity. However, no single parameter can be adjusted, consistent with scientific consensus, to eliminate the earthquake rate discrepancy. Applying a combination of these parametric adjustments yields an alternative earthquake source model that is more compatible with the historic data. The 475-year return period hazard for peak ground and 1-sec spectral acceleration resulting from this alternative source model differs from the hazard resulting from the

A fiber Bragg grating acceleration sensor for ground surveillance

NASA Astrophysics Data System (ADS)

Jiang, Shaodong; Zhang, Faxiang; Lv, Jingsheng; Ni, Jiasheng; Wang, Chang

2017-10-01

Ground surveillance system is a kind of intelligent monitoring equipment for detecting and tracking the ground target. This paper presents a fiber Bragg grating (FBG) acceleration sensor for ground surveillance, which has the characteristics of no power supply, anti-electromagnetic interference, easy large-scale networking, and small size. Which make it able to achieve the advantage of the ground surveillance system while avoiding the shortcoming of the electric sensing. The sensor has a double cantilever beam structure with a sensitivity of 1000 pm/g. Field experiment has been carried out on a flood beach to examine the sensor performance. The result shows that the detection distance on the walking of personnel reaches 70m, and the detection distance on the ordinary motor vehicle reaches 200m. The performance of the FBG sensor can satisfy the actual needs of the ground surveillance system.

Evidence for earthquake triggering of large landslides in coastal Oregon, USA

USGS Publications Warehouse

Schulz, W.H.; Galloway, S.L.; Higgins, J.D.

2012-01-01

Landslides are ubiquitous along the Oregon coast. Many are large, deep slides in sedimentary rock and are dormant or active only during the rainy season. Morphology, observed movement rates, and total movement suggest that many are at least several hundreds of years old. The offshore Cascadia subduction zone produces great earthquakes every 300–500 years that generate tsunami that inundate the coast within minutes. Many slides and slide-prone areas underlie tsunami evacuation and emergency response routes. We evaluated the likelihood of existing and future large rockslides being triggered by pore-water pressure increase or earthquake-induced ground motion using field observations and modeling of three typical slides. Monitoring for 2–9 years indicated that the rockslides reactivate when pore pressures exceed readily identifiable levels. Measurements of total movement and observed movement rates suggest that two of the rockslides are 296–336 years old (the third could not be dated). The most recent great Cascadia earthquake was M 9.0 and occurred during January 1700, while regional climatological conditions have been stable for at least the past 600 years. Hence, the estimated ages of the slides support earthquake ground motion as their triggering mechanism. Limit-equilibrium slope-stability modeling suggests that increased pore-water pressures could not trigger formation of the observed slides, even when accompanied by progressive strength loss. Modeling suggests that ground accelerations comparable to those recorded at geologically similar sites during the M 9.0, 11 March 2011 Japan Trench subduction-zone earthquake would trigger formation of the rockslides. Displacement modeling following the Newmark approach suggests that the rockslides would move only centimeters upon coseismic formation; however, coseismic reactivation of existing rockslides would involve meters of displacement. Our findings provide better understanding of the dynamic coastal bluff

Rupture Dynamics and Ground Motion from Earthquakes on Rough Faults in Heterogeneous Media

NASA Astrophysics Data System (ADS)

Bydlon, S. A.; Kozdon, J. E.; Duru, K.; Dunham, E. M.

2013-12-01

Heterogeneities in the material properties of Earth's crust scatter propagating seismic waves. The effects of scattered waves are reflected in the seismic coda and depend on the amplitude of the heterogeneities, spatial arrangement, and distance from source to receiver. In the vicinity of the fault, scattered waves influence the rupture process by introducing fluctuations in the stresses driving propagating ruptures. Further variability in the rupture process is introduced by naturally occurring geometric complexity of fault surfaces, and the stress changes that accompany slip on rough surfaces. Our goal is to better understand the origin of complexity in the earthquake source process, and to quantify the relative importance of source complexity and scattering along the propagation path in causing incoherence of high frequency ground motion. Using a 2D high order finite difference rupture dynamics code, we nucleate ruptures on either flat or rough faults that obey strongly rate-weakening friction laws. These faults are embedded in domains with spatially varying material properties characterized by Von Karman autocorrelation functions and their associated power spectral density functions, with variations in wave speed of approximately 5 to 10%. Flat fault simulations demonstrate that off-fault material heterogeneity, at least with this particular form and amplitude, has only a minor influence on the rupture process (i.e., fluctuations in slip and rupture velocity). In contrast, ruptures histories on rough faults in both homogeneous and heterogeneous media include much larger short-wavelength fluctuations in slip and rupture velocity. We therefore conclude that source complexity is dominantly influenced by fault geometric complexity. To examine contributions of scattering versus fault geometry on ground motions, we compute spatially averaged root-mean-square (RMS) acceleration values as a function of fault perpendicular distance for a homogeneous medium and several

Unusual downhole and surface free-field records near the Carquinez Strait bridges during the 24 August 2014 Mw6.0 South Napa, California earthquake

USGS Publications Warehouse

Çelebi, Mehmet; Ghahari, S. Farid; Taciroglu, Ertugrul

2015-01-01

This paper reports the results of Part A of a study of the recorded strong-motion accelerations at the well-instrumented network of the two side-by-side parallel bridges over the Carquinez Strait during the 24 August 2014 (Mw6.0 ) South Napa, Calif. earthquake that occurred at 03:20:44 PDT with epicentral coordinates 38.22N, 122.31W. (http://earthquake.usgs.gov/earthquakes/eqarchives/poster/2014/20140824.php, last accessed on October 17, 2014). Both bridges and two boreholes were instrumented by the California Strong motion Instrumentation Program (CSMIP) of California Geological Survey (CGS) (Shakal et al., 2014). A comprehensive comparison of several ground motion prediction equations as they relate to recorded ground motions of the earthquake is provided by Baltay and Boatright (2015).

Implications of next generation attenuation ground motion prediction equations for site coefficients used in earthquake resistant design

USGS Publications Warehouse

Borcherdt, Roger D.

2014-01-01

Proposals are developed to update Tables 11.4-1 and 11.4-2 of Minimum Design Loads for Buildings and Other Structures published as American Society of Civil Engineers Structural Engineering Institute standard 7-10 (ASCE/SEI 7–10). The updates are mean next generation attenuation (NGA) site coefficients inferred directly from the four NGA ground motion prediction equations used to derive the maximum considered earthquake response maps adopted in ASCE/SEI 7–10. Proposals include the recommendation to use straight-line interpolation to infer site coefficients at intermediate values of (average shear velocity to 30-m depth). The NGA coefficients are shown to agree well with adopted site coefficients at low levels of input motion (0.1 g) and those observed from the Loma Prieta earthquake. For higher levels of input motion, the majority of the adopted values are within the 95% epistemic-uncertainty limits implied by the NGA estimates with the exceptions being the mid-period site coefficient, Fv, for site class D and the short-period coefficient, Fa, for site class C, both of which are slightly less than the corresponding 95% limit. The NGA data base shows that the median value  of 913 m/s for site class B is more typical than 760 m/s as a value to characterize firm to hard rock sites as the uniform ground condition for future maximum considered earthquake response ground motion estimates. Future updates of NGA ground motion prediction equations can be incorporated easily into future adjustments of adopted site coefficients using procedures presented herein. 

Observing pre-earthquake features in the Earth atmosphere-ionosphere environment associated with 2017 Tehuantepec and Puebla earthquakes in Mexico

NASA Astrophysics Data System (ADS)

Ouzounov, D.; Pulinets, S. A.; Guiliani, G.; Hernandez-Pajares, M.; Garcia-Rigo, A.; Petrov, L.; Taylor, P. T.; Hatzopoulos, N.; Kafatos, M.

2017-12-01

We are presenting a multi parameter study of lithosphere/atmosphere /ionosphere transient phenomena observed in advance of the M8.2 Tehuantepec and M7.1Puebla earthquakes, the largest and most damaging earthquakes ever recorded in Mexico. We are collecting data from four instruments which recorded hourly and daily: 1.Ground Radon variations (Gamma network in Southern CA) ; 2. Outgoing long-wavelength radiation (OLR obtained from NPOES) on the top of the atmosphere (TOA), 3. Atmospheric chemical potential (ACP) obtained from NASA assimilation models and 4. Electron density variations in the ionosphere via GPS Total Electron Content (GPS/TEC). The September M8.2 earthquake was situated about 3200 kilometers south of two-radon monitoring stations in Orange, Southern California. Real time hourly data show a sharp increase on both sensors (160 kilometers apart) on Sept 2 ( 6 days prior to the M8.2 of 09.08.2017 ) and second anomaly appeared again on Sept 11 ( 7 days prior to the M7.1 of 09.19.2017). Those increases in radon coincide (with some delay) with an increase in the atmospheric chemical potential (on Sept. 03 and10 respectively) measured near the epicentral area from satellite data. And subsequently at the end of August there was an increase of infrared radiation observed which was associated with the acceleration of OLR at the TOA observed from NOAA polar orbit satellites reaching a maximum near the epicenter on Sept 5 and Sept 17. The GPS/Total Electron Content data indicated an increase of electron concentration in ionosphere on Sep 7 and Sep 18, 1-2 days before both earthquakes. Before the earthquake ground and satellite data both show a synergetic anomalous trend, a week before the M8.2 Tehuantepec of 09.08.2017 and continuously up to the Puebla earthquake(M7.1 of 09.19.2017) , although the radon variations were observed far from both epicentral areas. We examined the possible correlation between different pre-earthquake signals in the frame of a

Modeling continuous seismic velocity changes due to ground shaking in Chile

NASA Astrophysics Data System (ADS)

Gassenmeier, Martina; Richter, Tom; Sens-Schönfelder, Christoph; Korn, Michael; Tilmann, Frederik

2015-04-01

In order to investigate temporal seismic velocity changes due to earthquake related processes and environmental forcing, we analyze 8 years of ambient seismic noise recorded by the Integrated Plate Boundary Observatory Chile (IPOC) network in northern Chile between 18° and 25° S. The Mw 7.7 Tocopilla earthquake in 2007 and the Mw 8.1 Iquique earthquake in 2014 as well as numerous smaller events occurred in this area. By autocorrelation of the ambient seismic noise field, approximations of the Green's functions are retrieved. The recovered function represents backscattered or multiply scattered energy from the immediate neighborhood of the station. To detect relative changes of the seismic velocities we apply the stretching method, which compares individual autocorrelation functions to stretched or compressed versions of a long term averaged reference autocorrelation function. We use time windows in the coda of the autocorrelations, that contain scattered waves which are highly sensitive to minute changes in the velocity. At station PATCX we observe seasonal changes in seismic velocity as well as temporary velocity reductions in the frequency range of 4-6 Hz. The seasonal changes can be attributed to thermal stress changes in the subsurface related to variations of the atmospheric temperature. This effect can be modeled well by a sine curve and is subtracted for further analysis of short term variations. Temporary velocity reductions occur at the time of ground shaking usually caused by earthquakes and are followed by a recovery. We present an empirical model that describes the seismic velocity variations based on continuous observations of the local ground acceleration. Our hypothesis is that not only the shaking of earthquakes provokes velocity drops, but any small vibrations continuously induce minor velocity variations that are immediately compensated by healing in the steady state. We show that the shaking effect is accumulated over time and best described by

State-of-the-Art for Assessing Earthquake Hazards in the United States. Report 17. Interpretation of Strong Ground Motion Records.

DTIC Science & Technology

1981-10-01

earthquake. The analysis works from first "hysical principles and, so rar as possible, uses elementary ray theory and kinematic arguments. Nevertheless...elements of the more sophisticated theory of earthquake mechanisms and seismic wave propagation in the near field were taken into account in the...Broad Principles of Interpretation 163 4.2 Robust Estimation of Parameters 171 4.3 Some Remarks on High-Acceleration Values 180 4.4 The Focussing

Debris flow susceptibility assessment after the 2008 Wenchuan earthquake

NASA Astrophysics Data System (ADS)

Fan, Xuanmei; van Westen, Cees; Tang, Chenxiao; Tang, Chuan

2014-05-01

Due to a tremendous amount of loose material from landslides that occurred during the Wenchuan earthquake, the frequency and magnitude of debris flows have been immensely increased, causing many casualties and economic losses. This study attempts to assess the post-earthquake debris flow susceptibility based on catchment units in the Wenchuan county, one of the most severely damaged county by the earthquake. The post earthquake debris flow inventory was created by RS image interpretation and field survey. According to our knowledge to the field, several relevant factors were determined as indicators for post-earthquake debris flow occurrence, including the distance to fault surface rupture, peak ground acceleration (PGA), coseismic landslide density, rainfall data, internal relief, slope, drainage density, stream steepness index, existing mitigation works etc. These indicators were then used as inputs in a heuristic model that was developed by adapting the Spatial Multi Criteria Evaluation (SMCE) method. The relative importance of the indicators was evaluated according to their contributions to the debris flow events that have occurred after the earthquake. The ultimate goal of this study is to estimate the relative likelihood of debris flow occurrence in each catchment, and use this result together with elements at risk and vulnerability information to assess the changing risk of the most susceptible catchment.

Ground motion in the presence of complex topography: Earthquake and ambient noise sources

USGS Publications Warehouse

Hartzell, Stephen; Meremonte, Mark; Ramírez-Guzmán, Leonardo; McNamara, Daniel

2014-01-01

To study the influence of topography on ground motion, eight seismic recorders were deployed for a period of one year over Poverty Ridge on the east side of the San Francisco Bay Area, California. This location is desirable because of its proximity to local earthquake sources and the significant topographic relief of the array (439 m). Topographic amplification is evaluated as a function of frequency using a variety of methods, including reference‐site‐based spectral ratios and single‐station horizontal‐to‐vertical spectral ratios using both shear waves from earthquakes and ambient noise. Field observations are compared with the predicted ground motion from an accurate digital model of the topography and a 3D local velocity model. Amplification factors from the theoretical calculations are consistent with observations. The fundamental resonance of the ridge is prominently observed in the spectra of data and synthetics; however, higher‐frequency peaks are also seen primarily for sources in line with the major axis of the ridge, perhaps indicating higher resonant modes. Excitations of lateral ribs off of the main ridge are also seen at frequencies consistent with their dimensions. The favored directions of resonance are shown to be transverse to the major axes of the topographic features.

A reliable simultaneous representation of seismic hazard and of ground shaking recurrence

NASA Astrophysics Data System (ADS)

Peresan, A.; Panza, G. F.; Magrin, A.; Vaccari, F.

2015-12-01

Different earthquake hazard maps may be appropriate for different purposes - such as emergency management, insurance and engineering design. Accounting for the lower occurrence rate of larger sporadic earthquakes may allow to formulate cost-effective policies in some specific applications, provided that statistically sound recurrence estimates are used, which is not typically the case of PSHA (Probabilistic Seismic Hazard Assessment). We illustrate the procedure to associate the expected ground motions from Neo-deterministic Seismic Hazard Assessment (NDSHA) to an estimate of their recurrence. Neo-deterministic refers to a scenario-based approach, which allows for the construction of a broad range of earthquake scenarios via full waveforms modeling. From the synthetic seismograms the estimates of peak ground acceleration, velocity and displacement, or any other parameter relevant to seismic engineering, can be extracted. NDSHA, in its standard form, defines the hazard computed from a wide set of scenario earthquakes (including the largest deterministically or historically defined credible earthquake, MCE) and it does not supply the frequency of occurrence of the expected ground shaking. A recent enhanced variant of NDSHA that reliably accounts for recurrence has been developed and it is applied to the Italian territory. The characterization of the frequency-magnitude relation can be performed by any statistically sound method supported by data (e.g. multi-scale seismicity model), so that a recurrence estimate is associated to each of the pertinent sources. In this way a standard NDSHA map of ground shaking is obtained simultaneously with the map of the corresponding recurrences. The introduction of recurrence estimates in NDSHA naturally allows for the generation of ground shaking maps at specified return periods. This permits a straightforward comparison between NDSHA and PSHA maps.

Earthquake Dynamics in Laboratory Model and Simulation - Accelerated Creep as Precursor of Instabilities

NASA Astrophysics Data System (ADS)

Grzemba, B.; Popov, V. L.; Starcevic, J.; Popov, M.

2012-04-01

Shallow earthquakes can be considered as a result of tribological instabilities, so called stick-slip behaviour [1,2], meaning that sudden slip occurs at already existing rupture zones. From a contact mechanics point of view it is clear, that no motion can arise completely sudden, the material will always creep in an existing contact in the load direction before breaking loose. If there is a measureable creep before the instability, this could serve as a precursor. To examine this theory in detail, we built up an elementary laboratory model with pronounced stick-slip behaviour. Different material pairings, such as steel-steel, steel-glass and marble-granite, were analysed at different driving force rates. The displacement was measured with a resolution of 8 nm. We were able to show that a measureable accelerated creep precedes the instability. Near the instability, this creep is sufficiently regular to serve as a basis for a highly accurate prediction of the onset of macroscopic slip [3]. In our model a prediction is possible within the last few percents of the preceding stick time. We are hopeful to extend this period. Furthermore, we showed that the slow creep as well as the fast slip can be described very well by the Dieterich-Ruina-friction law, if we include the contribution of local contact rigidity. The simulation meets the experimental curves over five orders of magnitude. This friction law was originally formulated for rocks [4,5] and takes into account the dependency of the coefficient of friction on the sliding velocity and on the contact history. The simulations using the Dieterich-Ruina-friction law back up the observation of a universal behaviour of the creep's acceleration. We are working on several extensions of our model to more dimensions in order to move closer towards representing a full three-dimensional continuum. The first step will be an extension to two degrees of freedom to analyse the interdependencies of the instabilities. We also plan

Macroseismic Intensity and Instrumental Ground Motion Parameter Correlations for Central Mexico

NASA Astrophysics Data System (ADS)

Sandoval Gómez, H.; Ramirez Guzman, L.; Espindola, V.

2012-12-01

We present instrumental intensity prediction equations for earthquakes in Central Mexico based on the correlation of observed Instrumental Ground-Motion Parameters (IGMP) and Modified Mercalli Intensity (MMI) scale reports. The goal of this study is to provide a model that can be used by the near real-time earthquake response system operated by the Institutes of Engineering and Geophysics at the National Autonomous University of Mexico (UNAM), which delivers estimates of key information associated with the societal impact due to earthquakes not available in the immediate aftermath of the event. Correlations of MMI and IGMP have been derived in other countries with different tectonic settings and built environments, but this is the first study devoted to the development of equations for the central region of Mexico. The IGMP are obtained from records of several stations for earthquakes with Mw 5.0-8.0 from the seismic networks operated by UNAM and other institutions in Mexico. The MMI observations were primarily obtained from the Did You Feel It (DYFI) report service of the U.S. Geological Survey and re-interpreted MMI reports from UNAM earthquake bulletin archives. For each instrumental observation we assigned a mean MMI intensity based on the proximity of the site where reported value are available, constrained by geological conditions and a visual inspection to guarantee that the intensity would be within one unit of the assigned value; following the procedure by Atkinson and Kaka (2006). We derived correlations for peak ground velocity (pgv) and acceleration, and three spectral acceleration periods (T=1, 2 and 3 s). In addition, we analyzed the Mw and distance dependence. We concluded that pgv and the spectral accelerations are the most useful IGMP predictors for MMI in the region of interest and the correlations differ significantly from those obtained in regions with other tectonic settings and infrastructure vulnerabilities (e.g. Wald et al, 1999; Atkinson

A simple model for strong ground motions and response spectra

USGS Publications Warehouse

Safak, Erdal; Mueller, Charles; Boatwright, John

1988-01-01

A simple model for the description of strong ground motions is introduced. The model shows that response spectra can be estimated by using only four parameters of the ground motion, the RMS acceleration, effective duration and two corner frequencies that characterize the effective frequency band of the motion. The model is windowed band-limited white noise, and is developed by studying the properties of two functions, cumulative squared acceleration in the time domain, and cumulative squared amplitude spectrum in the frequency domain. Applying the methods of random vibration theory, the model leads to a simple analytical expression for the response spectra. The accuracy of the model is checked by using the ground motion recordings from the aftershock sequences of two different earthquakes and simulated accelerograms. The results show that the model gives a satisfactory estimate of the response spectra.

An atlas of ShakeMaps for selected global earthquakes

USGS Publications Warehouse

Allen, Trevor I.; Wald, David J.; Hotovec, Alicia J.; Lin, Kuo-Wan; Earle, Paul S.; Marano, Kristin D.

2008-01-01

An atlas of maps of peak ground motions and intensity 'ShakeMaps' has been developed for almost 5,000 recent and historical global earthquakes. These maps are produced using established ShakeMap methodology (Wald and others, 1999c; Wald and others, 2005) and constraints from macroseismic intensity data, instrumental ground motions, regional topographically-based site amplifications, and published earthquake-rupture models. Applying the ShakeMap methodology allows a consistent approach to combine point observations with ground-motion predictions to produce descriptions of peak ground motions and intensity for each event. We also calculate an estimated ground-motion uncertainty grid for each earthquake. The Atlas of ShakeMaps provides a consistent and quantitative description of the distribution and intensity of shaking for recent global earthquakes (1973-2007) as well as selected historic events. As such, the Atlas was developed specifically for calibrating global earthquake loss estimation methodologies to be used in the U.S. Geological Survey Prompt Assessment of Global Earthquakes for Response (PAGER) Project. PAGER will employ these loss models to rapidly estimate the impact of global earthquakes as part of the USGS National Earthquake Information Center's earthquake-response protocol. The development of the Atlas of ShakeMaps has also led to several key improvements to the Global ShakeMap system. The key upgrades include: addition of uncertainties in the ground motion mapping, introduction of modern ground-motion prediction equations, improved estimates of global seismic-site conditions (VS30), and improved definition of stable continental region polygons. Finally, we have merged all of the ShakeMaps in the Atlas to provide a global perspective of earthquake ground shaking for the past 35 years, allowing comparison with probabilistic hazard maps. The online Atlas and supporting databases can be found at http://earthquake.usgs.gov/eqcenter/shakemap/atlas.php/.

Seismic displacement of gently-sloping coastal and marine sediment under multidirectional earthquake loading

USGS Publications Warehouse

Kayen, Robert E.

2017-01-01

Gentle sediment-laden slopes are typical of the onshore coastal zone and offshore continental shelf and slope. Coastal sediment are commonly young weakly consolidated materials that are well stratified, have low strength, and can mobilize shear displacements at low levels of stress. Seismically-driven plastic displacements of these sediment pose a hazard to coastal cities, buried onshore utilities, and offshore infrastructure like harbor protection and outfalls. One-dimensional rigid downslope-directed Newmark sliding block analyses have been used to predict earthquake deformations generally on steeper slopes that are modeled as frictional materials. This study probes the effect of multidirectional earthquake motions on inertial displacements of gently sloping ground of the coastal and offshore condition where soft-compliant soil is expected. Toward that objective, this investigation seeks to understand the effect on Newmark-type displacements of [1] multidirectional earthquake shaking and [2] soil compliance. In order to model multidirectional effects, the earthquake motions are rotated into the local slope strike- and dip-components. On gently sloping ground, including the strike component of motion always results in a larger and more accurate shear stress vector. Strike motions are found to contribute to downslope deformations on any declivity. Compliant response of the soil mass also influences the plastic displacements. The magnitude of seismic displacements can be estimated with a simplified model using only the estimated soil yield-acceleration (ky) and the peak ground velocity (Vmax) of the earthquake motions. Compliance effects can be effectively mapped using the concept of Plastic Displacement Response Spectra (PDRS).

Rapid modeling of complex multi-fault ruptures with simplistic models from real-time GPS: Perspectives from the 2016 Mw 7.8 Kaikoura earthquake

NASA Astrophysics Data System (ADS)

Crowell, B.; Melgar, D.

2017-12-01

The 2016 Mw 7.8 Kaikoura earthquake is one of the most complex earthquakes in recent history, rupturing across at least 10 disparate faults with varying faulting styles, and exhibiting intricate surface deformation patterns. The complexity of this event has motivated the need for multidisciplinary geophysical studies to get at the underlying source physics to better inform earthquake hazards models in the future. However, events like Kaikoura beg the question of how well (or how poorly) such earthquakes can be modeled automatically in real-time and still satisfy the general public and emergency managers. To investigate this question, we perform a retrospective real-time GPS analysis of the Kaikoura earthquake with the G-FAST early warning module. We first perform simple point source models of the earthquake using peak ground displacement scaling and a coseismic offset based centroid moment tensor (CMT) inversion. We predict ground motions based on these point sources as well as simple finite faults determined from source scaling studies, and validate against true recordings of peak ground acceleration and velocity. Secondly, we perform a slip inversion based upon the CMT fault orientations and forward model near-field tsunami maximum expected wave heights to compare against available tide gauge records. We find remarkably good agreement between recorded and predicted ground motions when using a simple fault plane, with the majority of disagreement in ground motions being attributable to local site effects, not earthquake source complexity. Similarly, the near-field tsunami maximum amplitude predictions match tide gauge records well. We conclude that even though our models for the Kaikoura earthquake are devoid of rich source complexities, the CMT driven finite fault is a good enough "average" source and provides useful constraints for rapid forecasting of ground motion and near-field tsunami amplitudes.

Ground motion values for use in the seismic design of the Trans-Alaska Pipeline system

USGS Publications Warehouse

Page, Robert A.; Boore, D.M.; Joyner, W.B.; Coulter, H.W.

1972-01-01

The proposed trans-Alaska oil pipeline, which would traverse the state north to south from Prudhoe Bay on the Arctic coast to Valdez on Prince William Sound, will be subject to serious earthquake hazards over much of its length. To be acceptable from an environmental standpoint, the pipeline system is to be designed to minimize the potential of oil leakage resulting from seismic shaking, faulting, and seismically induced ground deformation. The design of the pipeline system must accommodate the effects of earthquakes with magnitudes ranging from 5.5 to 8.5 as specified in the 'Stipulations for Proposed Trans-Alaskan Pipeline System.' This report characterizes ground motions for the specified earthquakes in terms of peak levels of ground acceleration, velocity, and displacement and of duration of shaking. Published strong motion data from the Western United States are critically reviewed to determine the intensity and duration of shaking within several kilometers of the slipped fault. For magnitudes 5 and 6, for which sufficient near-fault records are available, the adopted ground motion values are based on data. For larger earthquakes the values are based on extrapolations from the data for smaller shocks, guided by simplified theoretical models of the faulting process.

Characteristics of Landslides Triggered by Mw 7.8 2015 Gorkha Earthquake

NASA Astrophysics Data System (ADS)

Dhital, Smriti

The Mw 7.8 Gorkha earthquake struck central Nepal on April 25, 2015 and brought about a huge loss of life and property. The quake was also responsible for the generation of a large number of landslides. They blocked highways, devastated villages, and temporarily dammed some rivers. About 14,670 landslips were triggered off by the main shock and its numerous large aftershocks. Among the detected failures, about 23% had an area greater than 100 m2. Since such failures can directly affect people's life and property, they are considered for further investigation in this study. A comparison of these coseismic landslides with the 29 historical failures reveals that these landslides slightly exceed in number from those expected for the peak ground acceleration observed due to these earthquakes. The landslides seem to be concentrated within the area of the fault rupture surface. About 90% of the detected landslips could be classified as earth falls. The areas having relatively soft rocks, such as slates, shales, schists and phyllites of the Lesser Himalaya, suffered from a greater number of failures. The landslides had a strong correlation with the peak ground acceleration and they also showed a positive correlation with some landslide-susceptible geological formations composing the study area.

High Frequency Cut-off Characteristics of Strong Ground Motion Records at Hard Sites, Subduction and Intra-Slab Earthquakes

NASA Astrophysics Data System (ADS)

Kagawa, T.; Tsurugi, M.; Irikura, K.

2006-12-01

A study on high frequency cut-off characteristics of strong ground motion is presented for subduction and intra- slab earthquakes in Japan. In the latest decade, observed records at hard sites are published by NIED, National Research Institute for Earth Science and Disaster Prevention, and JCOLD, Japan Commission on Large Dams. Especially, KiK-net and K-NET maintained by NIED have been providing high quality data to study high-frequency characteristics. Kagawa et al.(2003) studied the characteristics for crustal earthquakes. We apply the same methodology to the recently observed Japanese records due to subduction and intra-slab earthquakes. We assume a Butterworth type high-cut filter with limit frequency (fmax) and its power factor. These two parameters were derived from Fourier spectrum of observed records fitting the theoretical filter shape. After analyzing the result from view points of site, path, or source effects, an averaged filter model is proposed with its standard deviation. Kagawa et al.(2003) derived average as 8.3 Hz with power factor of 1.92. It is used for strong ground motion simulation. We will propose parameters for the high-cut filters of subduction and intra-slab earthquakes and compare them with the results by Kagawa et al.(2003). REFERENCES: Kagawa et al. (2003), 27JEES (in Japanese with English Abstract).

Earthquake early warning for Romania - most recent improvements

NASA Astrophysics Data System (ADS)

Marmureanu, Alexandru; Elia, Luca; Martino, Claudio; Colombelli, Simona; Zollo, Aldo; Cioflan, Carmen; Toader, Victorin; Marmureanu, Gheorghe; Marius Craiu, George; Ionescu, Constantin

2014-05-01

EWS for Vrancea earthquakes uses the time interval (28-32 sec.) between the moment when the earthquake is detected by the local seismic network installed in the epicenter area (Vrancea) and the arrival time of the seismic waves in the protected area (Bucharest) to send earthquake warning to users. In the last years, National Institute for Earth Physics (NIEP) upgraded its seismic network in order to cover better the seismic zones of Romania. Currently the National Institute for Earth Physics (NIEP) operates a real-time seismic network designed to monitor the seismic activity on the Romania territory, dominated by the Vrancea intermediate-depth (60-200 km) earthquakes. The NIEP real-time network consists of 102 stations and two seismic arrays equipped with different high quality digitizers (Kinemetrics K2, Quanterra Q330, Quanterra Q330HR, PS6-26, Basalt), broadband and short period seismometers (CMG3ESP, CMG40T, KS2000, KS54000, KS2000, CMG3T,STS2, SH-1, S13, Ranger, gs21, Mark l22) and acceleration sensors (Episensor). Recent improvement of the seismic network and real-time communication technologies allows implementation of a nation-wide EEWS for Vrancea and other seismic sources from Romania. We present a regional approach to Earthquake Early Warning for Romania earthquakes. The regional approach is based on PRESTo (Probabilistic and Evolutionary early warning SysTem) software platform: PRESTo processes in real-time three channel acceleration data streams: once the P-waves arrival have been detected, it provides earthquake location and magnitude estimations, and peak ground motion predictions at target sites. PRESTo is currently implemented in real- time at National Institute for Earth Physics, Bucharest for several months in parallel with a secondary EEWS. The alert notification is issued only when both systems validate each other. Here we present the results obtained using offline earthquakes originating from Vrancea area together with several real

Modeling the Interaction between Fluid Pressure and Faulting in an Earthquake Swarm at Long Valley Caldera

NASA Astrophysics Data System (ADS)

Haase, J. S.; Soliman, M.; Kim, H.; Jaiswal, P.; Saunders, J. K.; Vernon, F.; Zhang, W.

2016-12-01

This work focuses on quantifying ground motions and their effects in Oklahoma near the location of the 2016 Mw 5.8 Pawnee earthquake, where seismicity has been increasing due to wastewater injection related to oil and natural gas production. Much of the building inventory in Oklahoma was constructed before the increase in seismicity and before the implementation of earthquake design and detailing provisions for reinforced concrete (RC) structures. We will use combined GPS/seismic monitoring techniques to measure ground motion in the field and the response of structures to this ground motion. Several Oklahoma State University buildings experienced damage due to the Pawnee earthquake. The USGS Shake Map product estimated peak ground acceleration (PGA) ranging from 0.12g to 0.15g at campus locations. We are deploying a high-rate GPS sensor and accelerometer on the roof and another accelerometer at ground level of a 12-story RC structure and at selected field sites in order to collect ambient noise data and nearby seismicity. The longer period recording characteristics of the GPS/seismic system are particularly well adapted to monitoring these large structures in the event of a significant earthquake. Gross characteristics of the structural system are described, which consists of RC columns and RC slabs in all stories. We conducted a preliminary structural analysis including modal analysis and response spectrum analysis based on a finite element (FE) simulation, which indicated that the period associated with the first X-axis bending, first torsional, and first Y-axis bending modes are 2.2 s, 2.1 s, and 1.8 s, respectively. Next, a preliminary analysis was conducted to estimate the range of expected deformation at the roof level for various earthquake excitations. The earthquake analysis shows a maximum roof displacement of 5 and 7 cm in the horizontal directions resulting from earthquake loads with PGA of 0.2g, well above the noise level of the combined GPS

Some observations on colocated and closely spaced strong ground-motion records of the 1999 Chi-Chi, Taiwan, earthquake

USGS Publications Warehouse

Wang, G.-Q.; Boore, D.M.; Igel, H.; Zhou, X.-Y.

2003-01-01

The digital accelerograph network installed in Taiwan produced a rich set of records from the 20 September 1999 Chi-Chi, Taiwan earthquake (Mw 7.6). Teledyne Geotech model A-800 and A-900A* digital accelerographs were colocated at 22 stations that recorded this event. Comparisons of the amplitudes, frequency content, and baseline offsets show that records from several of the A-800 accelerographs are considerably different than those from the colocated A-900A accelerographs. On this basis, and in view of the more thorough predeployment testing of the newer A-900A instruments, we recommend that the records from the A-800 instruments be used with caution in analyses of the mainshock and aftershocks. At the Hualien seismic station two A-900A and one A-800 instruments were colocated, along with a Global Positioning System instrument. Although the records from the two A-900A instruments are much more similar than those from a colocated A-800 instrument, both three-component records contain unpredictable baseline offsets, which produced completely unrealistic ground displacements derived from the accelerations by double integration, as do many of the strong-motion data from this event; the details of the baseline offsets differ considerably on the two three-component records. There are probably numerous sources of the baseline offsets, including sources external to the instruments, such as tilting or rotation of the ground, and sources internal to the instruments, such as electrical or mechanical hysteresis in the sensors. For the two colocated A-900A records at the Hualien seismic station, however, the differences in the baseline offsets suggest that the principal source is some transient disturbance within the instrument. The baseline offsets generally manifest themselves in the acceleration time series as pulses or steps, either singly or in combination. We find a 0.015-Hz low-cut filter can almost completely eliminate the effects of the baseline offsets, but then

Reducing process delays for real-time earthquake parameter estimation - An application of KD tree to large databases for Earthquake Early Warning

NASA Astrophysics Data System (ADS)

Yin, Lucy; Andrews, Jennifer; Heaton, Thomas

2018-05-01

Earthquake parameter estimations using nearest neighbor searching among a large database of observations can lead to reliable prediction results. However, in the real-time application of Earthquake Early Warning (EEW) systems, the accurate prediction using a large database is penalized by a significant delay in the processing time. We propose to use a multidimensional binary search tree (KD tree) data structure to organize large seismic databases to reduce the processing time in nearest neighbor search for predictions. We evaluated the performance of KD tree on the Gutenberg Algorithm, a database-searching algorithm for EEW. We constructed an offline test to predict peak ground motions using a database with feature sets of waveform filter-bank characteristics, and compare the results with the observed seismic parameters. We concluded that large database provides more accurate predictions of the ground motion information, such as peak ground acceleration, velocity, and displacement (PGA, PGV, PGD), than source parameters, such as hypocenter distance. Application of the KD tree search to organize the database reduced the average searching process by 85% time cost of the exhaustive method, allowing the method to be feasible for real-time implementation. The algorithm is straightforward and the results will reduce the overall time of warning delivery for EEW.

Ground Motion Prediction Model Using Adaptive Neuro-Fuzzy Inference Systems: An Example Based on the NGA-West 2 Data

NASA Astrophysics Data System (ADS)

Ameur, Mourad; Derras, Boumédiène; Zendagui, Djawed

2018-03-01

Adaptive neuro-fuzzy inference systems (ANFIS) are used here to obtain the robust ground motion prediction model (GMPM). Avoiding a priori functional form, ANFIS provides fully data-driven predictive models. A large subset of the NGA-West2 database is used, including 2335 records from 580 sites and 137 earthquakes. Only shallow earthquakes and recordings corresponding to stations with measured V s30 properties are selected. Three basics input parameters are chosen: the moment magnitude ( Mw), the Joyner-Boore distance ( R JB) and V s30. ANFIS model output is the peak ground acceleration (PGA), peak ground velocity (PGV) and 5% damped pseudo-spectral acceleration (PSA) at periods from 0.01 to 4 s. A procedure similar to the random-effects approach is developed to provide between- and within-event standard deviations. The total standard deviation (SD) varies between [0.303 and 0.360] (log10 units) depending on the period. The ground motion predictions resulting from such simple three explanatory variables ANFIS models are shown to be comparable to the most recent NGA results (e.g., Boore et al., in Earthquake Spectra 30:1057-1085, 2014; Derras et al., in Earthquake Spectra 32:2027-2056, 2016). The main advantage of ANFIS compared to artificial neuronal network (ANN) is its simple and one-off topology: five layers. Our results exhibit a number of physically sound features: magnitude scaling of the distance dependency, near-fault saturation distance increasing with magnitude and amplification on soft soils. The ability to implement ANFIS model using an analytic equation and Excel is demonstrated.

Ground Motion Prediction Model Using Adaptive Neuro-Fuzzy Inference Systems: An Example Based on the NGA-West 2 Data

NASA Astrophysics Data System (ADS)

Ameur, Mourad; Derras, Boumédiène; Zendagui, Djawed

2017-12-01

Adaptive neuro-fuzzy inference systems (ANFIS) are used here to obtain the robust ground motion prediction model (GMPM). Avoiding a priori functional form, ANFIS provides fully data-driven predictive models. A large subset of the NGA-West2 database is used, including 2335 records from 580 sites and 137 earthquakes. Only shallow earthquakes and recordings corresponding to stations with measured V s30 properties are selected. Three basics input parameters are chosen: the moment magnitude (Mw), the Joyner-Boore distance (R JB) and V s30. ANFIS model output is the peak ground acceleration (PGA), peak ground velocity (PGV) and 5% damped pseudo-spectral acceleration (PSA) at periods from 0.01 to 4 s. A procedure similar to the random-effects approach is developed to provide between- and within-event standard deviations. The total standard deviation (SD) varies between [0.303 and 0.360] (log10 units) depending on the period. The ground motion predictions resulting from such simple three explanatory variables ANFIS models are shown to be comparable to the most recent NGA results (e.g., Boore et al., in Earthquake Spectra 30:1057-1085, 2014; Derras et al., in Earthquake Spectra 32:2027-2056, 2016). The main advantage of ANFIS compared to artificial neuronal network (ANN) is its simple and one-off topology: five layers. Our results exhibit a number of physically sound features: magnitude scaling of the distance dependency, near-fault saturation distance increasing with magnitude and amplification on soft soils. The ability to implement ANFIS model using an analytic equation and Excel is demonstrated.

Earthquake early warning using P-waves that appear after initial S-waves

NASA Astrophysics Data System (ADS)

Kodera, Y.

2017-12-01

As measures for underprediction for large earthquakes with finite faults and overprediction for multiple simultaneous earthquakes, Hoshiba (2013), Hoshiba and Aoki (2015), and Kodera et al. (2016) proposed earthquake early warning (EEW) methods that directly predict ground motion by computing the wave propagation of observed ground motion. These methods are expected to predict ground motion with a high accuracy even for complicated scenarios because these methods do not need source parameter estimation. On the other hand, there is room for improvement in their rapidity because they predict strong motion prediction mainly based on the observation of S-waves and do not explicitly use P-wave information available before the S-waves. In this research, we propose a real-time P-wave detector to incorporate P-wave information into these wavefield-estimation approaches. P-waves within a few seconds from the P-onsets are commonly used in many existing EEW methods. In addition, we focus on P-waves that may appear in the later part of seismic waves. Kurahashi and Irikura (2013) mentioned that P-waves radiated from strong motion generation areas (SMGAs) were recognizable after S-waves of the initial rupture point in the 2011 off the Pacific coast of Tohoku earthquake (Mw 9.0) (the Tohoku-oki earthquake). Detecting these P-waves would enhance the rapidity of prediction for the peak ground motion generated by SMGAs. We constructed a real-time P-wave detector that uses a polarity analysis. Using acceleration records in boreholes of KiK-net (band-pass filtered around 0.5-10 Hz with site amplification correction), the P-wave detector performed the principal component analysis with a sliding window of 4 s and calculated P-filter values (e.g. Ross and Ben-Zion, 2014). The application to the Tohoku-oki earthquake (Mw 9.0) showed that (1) peaks of P-filter that corresponded to SMGAs appeared in several stations located near SMGAs and (2) real-time seismic intensities (Kunugi et al

Urban MEMS based seismic network for post-earthquakes rapid disaster assessment

NASA Astrophysics Data System (ADS)

D'Alessandro, Antonino; Luzio, Dario; D'Anna, Giuseppe

2014-05-01

worship. The waveforms recorded could be promptly used to determine ground-shaking parameters, like peak ground acceleration/velocity/displacement, Arias and Housner intensity, that could be all used to create, few seconds after a strong earthquakes, shaking maps at urban scale. These shaking maps could allow to quickly identify areas of the town center that have had the greatest earthquake resentment. When a strong seismic event occur, the beginning of the ground motion observed at the site could be used to predict the ensuing ground motion at the same site and so to realize a short term earthquake early warning system. The data acquired after a moderate magnitude earthquake, would provide valuable information for the detail seismic microzonation of the area based on direct earthquake shaking observations rather than from a model-based or indirect methods. In this work, we evaluate the feasibility and effectiveness of such seismic network taking in to account both technological, scientific and economic issues. For this purpose, we have simulated the creation of a MEMS based urban seismic network in a medium size city. For the selected town, taking into account the instrumental specifics, the array geometry and the environmental noise, we investigated the ability of the planned network to detect and measure earthquakes of different magnitude generated from realistic near seismogentic sources.

Regional liquefaction hazard evaluation following the 2010-2011 Christchurch (New Zealand) earthquake sequence

NASA Astrophysics Data System (ADS)

Begg, John; Brackley, Hannah; Irwin, Marion; Grant, Helen; Berryman, Kelvin; Dellow, Grant; Scott, David; Jones, Katie; Barrell, David; Lee, Julie; Townsend, Dougal; Jacka, Mike; Harwood, Nick; McCahon, Ian; Christensen, Steve

2013-04-01

Following the damaging 4 Sept 2010 Mw7.1 Darfield Earthquake, the 22 Feb 2011 Christchurch Earthquake and subsequent damaging aftershocks, we completed a liquefaction hazard evaluation for c. 2700 km2 of the coastal Canterbury region. Its purpose was to distinguish at a regional scale areas of land that, in the event of strong ground shaking, may be susceptible to damaging liquefaction from areas where damaging liquefaction is unlikely. This information will be used by local government for defining liquefaction-related geotechnical investigation requirements for consent applications. Following a review of historic records of liquefaction and existing liquefaction assessment maps, we undertook comprehensive new work that included: a geologic context from existing geologic maps; geomorphic mapping using LiDAR and integrating existing soil map data; compilation of lithological data for the surficial 10 m from an extensive drillhole database; modelling of depth to unconfined groundwater from existing subsurface and surface water data. Integrating and honouring all these sources of information, we mapped areas underlain by materials susceptible to liquefaction (liquefaction-prone lithologies present, or likely, in the near-surface, with shallow unconfined groundwater) from areas unlikely to suffer widespread liquefaction damage. Comparison of this work with more detailed liquefaction susceptibility assessment based on closely spaced geotechnical probes in Christchurch City provides a level of confidence in these results. We tested our susceptibility map by assigning a matrix of liquefaction susceptibility rankings to lithologies recorded in drillhole logs and local groundwater depths, then applying peak ground accelerations for four earthquake scenarios from the regional probabilistic seismic hazard model (25 year return = 0.13g; 100 year return = 0.22g; 500 year return = 0.38g and 2500 year return = 0.6g). Our mapped boundary between liquefaction-prone areas and areas

Spatiotemporal seismic velocity change in the Earth's subsurface associated with large earthquake: contribution of strong ground motion and crustal deformation

NASA Astrophysics Data System (ADS)

Sawazaki, K.

2016-12-01

It is well known that seismic velocity of the subsurface medium changes after a large earthquake. The cause of the velocity change is roughly attributed to strong ground motion (dynamic strain change), crustal deformation (static strain change), and fracturing around the fault zone. Several studies have revealed that the velocity reduction down to several percent concentrates at the depths shallower than several hundred meters. The amount of velocity reduction correlates well with the intensity of strong ground motion, which indicates that the strong motion is the primary cause of the velocity reduction. Although some studies have proposed contributions of coseismic static strain change and fracturing around fault zone to the velocity change, separation of their contributions from the site-related velocity change is usually difficult. Velocity recovery after a large earthquake is also widely observed. The recovery process is generally proportional to logarithm of the lapse time, which is similar to the behavior of "slow dynamics" recognized in laboratory experiments. The time scale of the recovery is usually months to years in field observations, while it is several hours in laboratory experiments. Although the factor that controls the recovery speed is not well understood, cumulative strain change due to post-seismic deformation, migration of underground water, mechanical and chemical reactions on the crack surface could be the candidate. In this study, I summarize several observations that revealed spatiotemporal distribution of seismic velocity change due to large earthquakes; especially I focus on the case of the M9.0 2011 Tohoku earthquake. Combining seismograms of Hi-net (high-sensitivity) and KiK-net (strong motion), geodetic records of GEONET and the seafloor GPS/Acoustic ranging, I investigate contribution of the strong ground motion and crustal deformation to the velocity change associated with the Tohoku earthquake, and propose a gross view of

Stochastic strong ground motion simulations for the intermediate-depth earthquakes of the south Aegean subduction zone

NASA Astrophysics Data System (ADS)

Kkallas, Harris; Papazachos, Konstantinos; Boore, David; Margaris, Vasilis

2015-04-01

We have employed the stochastic finite-fault modelling approach of Motazedian and Atkinson (2005), as described by Boore (2009), for the simulation of Fourier spectra of the Intermediate-depth earthquakes of the south Aegean subduction zone. The stochastic finite-fault method is a practical tool for simulating ground motions of future earthquakes which requires region-specific source, path and site characterizations as input model parameters. For this reason we have used data from both acceleration-sensor and broadband velocity-sensor instruments from intermediate-depth earthquakes with magnitude of M 4.5-6.7 that occurred in the south Aegean subduction zone. Source mechanisms for intermediate-depth events of north Aegean subduction zone are either collected from published information or are constrained using the main faulting types from Kkallas et al. (2013). The attenuation parameters for simulations were adopted from Skarladoudis et al. (2013) and are based on regression analysis of a response spectra database. The site amplification functions for each soil class were adopted from Klimis et al., (1999), while the kappa values were constrained from the analysis of the EGELADOS network data from Ventouzi et al., (2013). The investigation of stress-drop values was based on simulations performed with the EXSIM code for several ranges of stress drop values and by comparing the results with the available Fourier spectra of intermediate-depth earthquakes. Significant differences regarding the strong-motion duration, which is determined from Husid plots (Husid, 1969), have been identified between the for-arc and along-arc stations due to the effect of the low-velocity/low-Q mantle wedge on the seismic wave propagation. In order to estimate appropriate values for the duration of P-waves, we have automatically picked P-S durations on the available seismograms. For the S-wave durations we have used the part of the seismograms starting from the S-arrivals and ending at the

Real-time Estimation of Fault Rupture Extent for Recent Large Earthquakes

NASA Astrophysics Data System (ADS)

Yamada, M.; Mori, J. J.

2009-12-01

Current earthquake early warning systems assume point source models for the rupture. However, for large earthquakes, the fault rupture length can be of the order of tens to hundreds of kilometers, and the prediction of ground motion at a site requires the approximated knowledge of the rupture geometry. Early warning information based on a point source model may underestimate the ground motion at a site, if a station is close to the fault but distant from the epicenter. We developed an empirical function to classify seismic records into near-source (NS) or far-source (FS) records based on the past strong motion records (Yamada et al., 2007). Here, we defined the near-source region as an area with a fault rupture distance less than 10km. If we have ground motion records at a station, the probability that the station is located in the near-source region is; P = 1/(1+exp(-f)) f = 6.046log10(Za) + 7.885log10(Hv) - 27.091 where Za and Hv denote the peak values of the vertical acceleration and horizontal velocity, respectively. Each observation provides the probability that the station is located in near-source region, so the resolution of the proposed method depends on the station density. The information of the fault rupture location is a group of points where the stations are located. However, for practical purposes, the 2-dimensional configuration of the fault is required to compute the ground motion at a site. In this study, we extend the methodology of NS/FS classification to characterize 2-dimensional fault geometries and apply them to strong motion data observed in recent large earthquakes. We apply a cosine-shaped smoothing function to the probability distribution of near-source stations, and convert the point fault location to 2-dimensional fault information. The estimated rupture geometry for the 2007 Niigata-ken Chuetsu-oki earthquake 10 seconds after the origin time is shown in Figure 1. Furthermore, we illustrate our method with strong motion data of the

Geomorphic and geologic controls of geohazards induced by Nepal’s 2015 Gorkha earthquake

USGS Publications Warehouse

Kargel, J.S.; Leonard, G.J.; Shugar, D. H.; Haritashya, U. K.; Bevington, A.; Fielding, E.J.; Fujita, K.; Geertsema, M.; Miles, E. S.; Steiner, J.; Anderson, E.; Bajracharya, S.; Bawden, G.W.; Breashears, D. F.; Byers, A.; Collins, B.; Dhital, M. R.; Donnellan, A.; Evans, T. L.; Geai, M. L.; Glasscoe, M. T.; Green, D.; Gurung, D. R.; Heijenk, R.; Hilborn, A.; Hudnut, K.; Huyck, C.; Immerzeel, W. W.; Liming, Jiang; Jibson, R.; Kaab, A.; Khanal, N. R.; Kirschbaum, D.; Kraaijenbrink, P. D. A.; Lamsal, D.; Shiyin, Liu; Mingyang, Lv; McKinney, D.; Nahirnick, N. K.; Zhuotong, Nan; Ojha, S.; Olsenholler, J.; Painter, T.H.; Pleasants, M.; Pratima, K. C.; Yuan, Q. I.; Raup, B.H.; Regmi, D.; Rounce, D. R.; Sakai, A.; Donghui, Shangguan; Shea, J. M.; Shrestha, A. B.; Shukla, A.; Stumm, D.; van der Kooij, M.; Voss, K.; Xin, Wang; Weihs, B.; Lizong, Wu; Xiaojun, Yao; Yoder, M. R.; Young, N.

2016-01-01

The Gorkha earthquake (magnitude 7.8) on 25 April 2015 and later aftershocks struck South Asia, killing ~9000 people and damaging a large region. Supported by a large campaign of responsive satellite data acquisitions over the earthquake disaster zone, our team undertook a satellite image survey of the earthquakes’ induced geohazards in Nepal and China and an assessment of the geomorphic, tectonic, and lithologic controls on quake-induced landslides. Timely analysis and communication aided response and recovery and informed decision-makers. We mapped 4312 coseismic and postseismic landslides. We also surveyed 491 glacier lakes for earthquake damage but found only nine landslide-impacted lakes and no visible satellite evidence of outbursts. Landslide densities correlate with slope, peak ground acceleration, surface downdrop, and specific metamorphic lithologies and large plutonic intrusions.

Environmentally Friendly Solution to Ground Hazards in Design of Bridges in Earthquake Prone Areas Using Timber Piles

NASA Astrophysics Data System (ADS)

Sadeghi, H.

2015-12-01

Bridges are major elements of infrastructure in all societies. Their safety and continued serviceability guaranties the transportation and emergency access in urban and rural areas. However, these important structures are subject to earthquake induced damages in structure and foundations. The basic approach to the proper support of foundations are a) distribution of imposed loads to foundation in a way they can resist those loads without excessive settlement and failure; b) modification of foundation ground with various available methods; and c) combination of "a" and "b". The engineers has to face the task of designing the foundations meeting all safely and serviceability criteria but sometimes when there are numerous environmental and financial constrains, the use of some traditional methods become inevitable. This paper explains the application of timber piles to improve ground resistance to liquefaction and to secure the abutments of short to medium length bridges in an earthquake/liquefaction prone area in Bohol Island, Philippines. The limitations of using the common ground improvement methods (i.e., injection, dynamic compaction) because of either environmental or financial concerns along with the abundance of timber in the area made the engineers to use a network of timber piles behind the backwalls of the bridge abutments. The suggested timber pile network is simulated by numerical methods and its safety is examined. The results show that the compaction caused by driving of the piles and bearing capacity provided by timbers reduce the settlement and lateral movements due to service and earthquake induced loads.

Atmosphere-Ionosphere Response to the M9 Tohoku Earthquake Revealed by Joined Satellite and Ground Observations. Preliminary Results

NASA Technical Reports Server (NTRS)

Ouzounov, Dimitar; Pulinets, Sergey; Romanov, Alexey; Tsybulya, Konstantin; Davidenko, Dimitri; Kafatos, Menas; Taylor, Patrick

2011-01-01

The recent M9 Tohoku Japan earthquake of March 11, 2011 was the largest recorded earthquake ever to hit this nation. We retrospectively analyzed the temporal and spatial variations of four different physical parameters - outgoing long wave radiation (OLR), GPS/TEC, Low-Earth orbit tomography and critical frequency foF2. These changes characterize the state of the atmosphere and ionosphere several days before the onset of this earthquake. Our first results show that on March 8th a rapid increase of emitted infrared radiation was observed from the satellite data and an anomaly developed near the epicenter. The GPS/TEC data indicate an increase and variation in electron density reaching a maximum value on March 8. Starting on this day in the lower ionospheric there was also confirmed an abnormal TEC variation over the epicenter. From March 3-11 a large increase in electron concentration was recorded at all four Japanese ground based ionosondes, which return to normal after the main earthquake. We found a positive correlation between the atmospheric and ionospheric anomalies and the Tohoku earthquake. This study may lead to a better understanding of the response of the atmosphere/ionosphere to the Great Tohoku earthquake.

Evaluation of the recorded ground motions for the unusual earthquake of 13 August 2006 ( M w 5.3) in Michoacán México

NASA Astrophysics Data System (ADS)

Ramírez-Gaytán, Alejandro; Jaimes, Miguel A.; Bandy, William L.; Huerfano, Victor M.; Salido-Ruiz, Ricardo A.

2015-10-01

The focal mechanism of the moderate earthquake of 13 August 2006 M w = 5.3, which occurred in the border coastal area between Michoacán and Colima, México, is unusual. As shown by the Global Centroid Moment Tensor (CMT) project and the Servicio Sismológico Nacional de Mexico (SSN), the thrust mechanism is striking almost perpendicularly to the majority of earthquakes occurring along the subduction zone of the Mexican Pacific continental margin which commonly strike nearly parallel to the trench. The purpose of this study is to analyze the observed ground motions of this particular event relative to those of the common events. First, we apply the H/V technique to verify that the stations involved in this study are nearly free of site effects. Then, we compare the observed ground motions with (i) three empirical ground motion prediction equations (GMPEs) appropriate for the region, (ii) ground motions of four real earthquakes with the common mechanism, and (iii) the Fourier spectrum of a selected common event.

Performance evaluation of setback buildings with open ground storey on plain and sloping ground under earthquake loadings and mitigation of failure

NASA Astrophysics Data System (ADS)

Ghosh, Rahul; Debbarma, Rama

2017-06-01

Setback structures are highly vulnerable during earthquakes due to its vertical geometrical and mass irregularity, but the vulnerability becomes higher if the structures also have stiffness irregularity in elevation. The risk factor of such structure may increase, if the structure rests on sloping ground. In this paper, an attempt has been made to evaluate the seismic performance of setback structures resting on plain ground as well as in the slope of a hill, with soft storey configuration. The analysis has been performed in three individual methods, equivalent static force method, response spectrum method and time history method and extreme responses have been recorded for open ground storeyed setback building. To mitigate this soft storey effect and the extreme responses, three individual mitigation techniques have been adopted and the best solution among these three techniques is presented.

Liquefaction at Oceano, California, during the 2003 San Simeon earthquake

USGS Publications Warehouse

Holzer, T.L.; Noce, T.E.; Bennett, M.J.; Tinsley, J. C.; Rosenberg, L.I.

2005-01-01

The 2003 M 6.5 San Simeon, California, earthquake caused liquefaction-induced lateral spreading at Oceano at an unexpectedly large distance from the seismogenic rupture. We conclude that the liquefaction was caused by ground motion that was enhanced by both rupture directivity in the mainshock and local site amplification by unconsolidated fine-grained deposits. Liquefaction occurred in sandy artificial fill and undisturbed eolian sand and fluvial deposits. The largest and most damaging lateral spread was caused by liquefaction of artificial fill; the head of this lateral spread coincided with the boundary between the artificial fill and undisturbed eolian sand deposits. Values of the liquefaction potential index, in general, were greater than 5 at liquefaction sites, the threshold value that has been proposed for liquefaction hazard mapping. Although the mainshock ground motion at Oceano was not recorded, peak ground acceleration was estimated to range from 0.25 and 0.28g on the basis of the liquefaction potential index and aftershock recordings. The estimates fall within the range of peak ground acceleration values associated with the modified Mercalli intensity = VII reported at the U.S. Geological Survey (USGS) "Did You Feel It?" web site.

Probabilistic seismic demand analysis using advanced ground motion intensity measures

USGS Publications Warehouse

Tothong, P.; Luco, N.

2007-01-01

One of the objectives in performance-based earthquake engineering is to quantify the seismic reliability of a structure at a site. For that purpose, probabilistic seismic demand analysis (PSDA) is used as a tool to estimate the mean annual frequency of exceeding a specified value of a structural demand parameter (e.g. interstorey drift). This paper compares and contrasts the use, in PSDA, of certain advanced scalar versus vector and conventional scalar ground motion intensity measures (IMs). One of the benefits of using a well-chosen IM is that more accurate evaluations of seismic performance are achieved without the need to perform detailed ground motion record selection for the nonlinear dynamic structural analyses involved in PSDA (e.g. record selection with respect to seismic parameters such as earthquake magnitude, source-to-site distance, and ground motion epsilon). For structural demands that are dominated by a first mode of vibration, using inelastic spectral displacement (Sdi) can be advantageous relative to the conventionally used elastic spectral acceleration (Sa) and the vector IM consisting of Sa and epsilon (??). This paper demonstrates that this is true for ordinary and for near-source pulse-like earthquake records. The latter ground motions cannot be adequately characterized by either Sa alone or the vector of Sa and ??. For structural demands with significant higher-mode contributions (under either of the two types of ground motions), even Sdi (alone) is not sufficient, so an advanced scalar IM that additionally incorporates higher modes is used.

Localized surface disruptions observed by InSAR during strong earthquakes in Java and Hawai'i

USGS Publications Warehouse

Poland, M.

2010-01-01

Interferometric Synthetic Aperture Radar data spanning strong earthquakes on the islands of Java and Hawai‘i in 2006 reveal patches of subsidence and incoherence indicative of localized ground failure. Interferograms spanning the 26 May 2006 Java earthquake suggest an area of about 7.5 km2 of subsidence (~2 cm) and incoherence south of the city of Yogyakarta that correlates with significant damage to housing, high modeled peak ground accelerations, and poorly consolidated geologic deposits. The subsidence and incoherence is inferred to be a result of intense shaking and/or damage. At least five subsidence patches on the west side of the Island of Hawai‘i, ranging 0.3–2.2 km2 in area and 3–8 cm in magnitude, occurred as a result of a pair of strong earthquakes on 15 October 2006. Although no felt reports or seismic data are available from the areas in Hawai‘i, the Java example suggests that the subsidence patches indicate areas of amplified earthquake shaking. Surprisingly, all subsidence areas in Hawai‘i were limited to recent, and supposedly stable, lava flows and may reflect geological conditions not detectable at the surface. In addition, two ‘a‘ā lava flows in Hawai‘i were partially incoherent in interferograms spanning the earthquakes, indicating surface disruption as a result of the earthquake shaking. Coearthquake incoherence of rubbly deposits, like ‘a‘ā flows, should be explored as a potential indicator of earthquake intensity and past strong seismic activity.

Development of a Low Cost Earthquake Early Warning System in Taiwan

NASA Astrophysics Data System (ADS)

Wu, Y. M.

2017-12-01

The National Taiwan University (NTU) developed an earthquake early warning (EEW) system for research purposes using low-cost accelerometers (P-Alert) since 2010. As of 2017, a total of 650 stations have been deployed and configured. The NTU system can provide earthquake information within 15 s of an earthquake occurrence. Thus, this system may provide early warnings for cities located more than 50 km from the epicenter. Additionally, the NTU system also has an onsite alert function that triggers a warning for incoming P-waves greater than a certain magnitude threshold, thus providing a 2-3 s lead time before peak ground acceleration (PGA) for regions close to an epicenter. Detailed shaking maps are produced by the NTU system within one or two minutes after an earthquake. Recently, a new module named ShakeAlarm has been developed. Equipped with real-time acceleration signals and the time-dependent anisotropic attenuation relationship of the PGA, ShakingAlarm can provide an accurate PGA estimation immediately before the arrival of the observed PGA. This unique advantage produces sufficient lead time for hazard assessment and emergency response, which is unavailable for traditional shakemap, which are based on only the PGA observed in real time. The performance of ShakingAlarm was tested with six M > 5.5 inland earthquakes from 2013 to 2016. Taking the 2016 M6.4 Meinong earthquake simulation as an example, the predicted PGA converges to a stable value and produces a predicted shake map and an isocontour map of the predicted PGA within 16 seconds of earthquake occurrence. Compared with traditional regional EEW system, ShakingAlarm can effectively identify possible damage regions and provide valuable early warning information (magnitude and PGA) for risk mitigation.

Model and parametric uncertainty in source-based kinematic models of earthquake ground motion

USGS Publications Warehouse

Hartzell, Stephen; Frankel, Arthur; Liu, Pengcheng; Zeng, Yuehua; Rahman, Shariftur

2011-01-01

Four independent ground-motion simulation codes are used to model the strong ground motion for three earthquakes: 1994 Mw 6.7 Northridge, 1989 Mw 6.9 Loma Prieta, and 1999 Mw 7.5 Izmit. These 12 sets of synthetics are used to make estimates of the variability in ground-motion predictions. In addition, ground-motion predictions over a grid of sites are used to estimate parametric uncertainty for changes in rupture velocity. We find that the combined model uncertainty and random variability of the simulations is in the same range as the variability of regional empirical ground-motion data sets. The majority of the standard deviations lie between 0.5 and 0.7 natural-log units for response spectra and 0.5 and 0.8 for Fourier spectra. The estimate of model epistemic uncertainty, based on the different model predictions, lies between 0.2 and 0.4, which is about one-half of the estimates for the standard deviation of the combined model uncertainty and random variability. Parametric uncertainty, based on variation of just the average rupture velocity, is shown to be consistent in amplitude with previous estimates, showing percentage changes in ground motion from 50% to 300% when rupture velocity changes from 2.5 to 2.9 km/s. In addition, there is some evidence that mean biases can be reduced by averaging ground-motion estimates from different methods.

Regional Earthquake Likelihood Models: A realm on shaky grounds?

NASA Astrophysics Data System (ADS)

Kossobokov, V.

2005-12-01

Seismology is juvenile and its appropriate statistical tools to-date may have a "medievil flavor" for those who hurry up to apply a fuzzy language of a highly developed probability theory. To become "quantitatively probabilistic" earthquake forecasts/predictions must be defined with a scientific accuracy. Following the most popular objectivists' viewpoint on probability, we cannot claim "probabilities" adequate without a long series of "yes/no" forecast/prediction outcomes. Without "antiquated binary language" of "yes/no" certainty we cannot judge an outcome ("success/failure"), and, therefore, quantify objectively a forecast/prediction method performance. Likelihood scoring is one of the delicate tools of Statistics, which could be worthless or even misleading when inappropriate probability models are used. This is a basic loophole for a misuse of likelihood as well as other statistical methods on practice. The flaw could be avoided by an accurate verification of generic probability models on the empirical data. It is not an easy task in the frames of the Regional Earthquake Likelihood Models (RELM) methodology, which neither defines the forecast precision nor allows a means to judge the ultimate success or failure in specific cases. Hopefully, the RELM group realizes the problem and its members do their best to close the hole with an adequate, data supported choice. Regretfully, this is not the case with the erroneous choice of Gerstenberger et al., who started the public web site with forecasts of expected ground shaking for `tomorrow' (Nature 435, 19 May 2005). Gerstenberger et al. have inverted the critical evidence of their study, i.e., the 15 years of recent seismic record accumulated just in one figure, which suggests rejecting with confidence above 97% "the generic California clustering model" used in automatic calculations. As a result, since the date of publication in Nature the United States Geological Survey website delivers to the public, emergency

Earthquake Hazard for Aswan High Dam Area

NASA Astrophysics Data System (ADS)

Ismail, Awad

2016-04-01

Earthquake activity and seismic hazard analysis are important components of the seismic aspects for very essential structures such as major dams. The Aswan High Dam (AHD) created the second man-made reservoir in the world (Lake Nasser) and is constructed near urban areas pose a high-risk potential for downstream life and property. The Dam area is one of the seismically active regions in Egypt and is occupied with several cross faults, which are dominant in the east-west and north-south. Epicenters were found to cluster around active faults in the northern part of Lake and AHD location. The space-time distribution and the relation of the seismicity with the lake water level fluctuations were studied. The Aswan seismicity separates into shallow and deep seismic zones, between 0 and 14 and 14 and 30 km, respectively. These two seismic zones behave differently over time, as indicated by the seismicity rate, lateral extent, b-value, and spatial clustering. It is characterized by earthquake swarm sequences showing activation of the clustering-events over time and space. The effect of the North African drought (1982 to present) is clearly seen in the reservoir water level. As it decreased and left the most active fault segments uncovered, the shallow activity was found to be more sensitive to rapid discharging than to the filling. This study indicates that geology, topography, lineations in seismicity, offsets in the faults, changes in fault trends and focal mechanisms are closely related. No relation was found between earthquake activity and both-ground water table fluctuations and water temperatures measured in wells located around the Kalabsha area. The peak ground acceleration is estimated in the dam site based on strong ground motion simulation. This seismic hazard analyses have indicated that AHD is stable with the present seismicity. The earthquake epicenters have recently took place approximately 5 km west of the AHD structure. This suggests that AHD dam must be

High Frequency Ground Motion from Finite Fault Rupture Simulations

NASA Astrophysics Data System (ADS)

Crempien, Jorge G. F.

There are many tectonically active regions on earth with little or no recorded ground motions. The Eastern United States is a typical example of regions with active faults, but with low to medium seismicity that has prevented sufficient ground motion recordings. Because of this, it is necessary to use synthetic ground motion methods in order to estimate the earthquake hazard a region might have. Ground motion prediction equations for spectral acceleration typically have geometric attenuation proportional to the inverse of distance away from the fault. Earthquakes simulated with one-dimensional layered earth models have larger geometric attenuation than the observed ground motion recordings. We show that as incident angles of rays increase at welded boundaries between homogeneous flat layers, the transmitted rays decrease in amplitude dramatically. As the receiver distance increases away from the source, the angle of incidence of up-going rays increases, producing negligible transmitted ray amplitude, thus increasing the geometrical attenuation. To work around this problem we propose a model in which we separate wave propagation for low and high frequencies at a crossover frequency, typically 1Hz. The high-frequency portion of strong ground motion is computed with a homogeneous half-space and amplified with the available and more complex one- or three-dimensional crustal models using the quarter wavelength method. We also make use of seismic coda energy density observations as scattering impulse response functions. We incorporate scattering impulse response functions into our Green's functions by convolving the high-frequency homogeneous half-space Green's functions with normalized synthetic scatterograms to reproduce scattering physical effects in recorded seismograms. This method was validated against ground motion for earthquakes recorded in California and Japan, yielding results that capture the duration and spectral response of strong ground motion.

Ground motions at the outermost limits of seismically triggered landslides

USGS Publications Warehouse

Jibson, Randall W.; Harp, Edwin L.

2016-01-01

Over the last few decades, we and our colleagues have conducted field investigations in which we mapped the outermost limits of triggered landslides in four earthquakes: 1987 Whittier Narrows, California (M 5.9), 1987 Superstition Hills, California (M 6.5), 1994 Northridge, California (M 6.7), and 2011 Mineral, Virginia (M 5.8). In an additional two earthquakes, 1976 Guatemala (M 7.5) and 1983 Coalinga, California (M 6.5), we determined limits using high‐resolution aerial‐photographic interpretation in conjunction with more limited ground investigation. Limits in these earthquakes were defined by the locations of the very smallest failures (<1  m3) from the most susceptible slopes that can be identified positively as having been triggered by earthquake shaking. Because we and our colleagues conducted all of these investigations, consistent methodology and criteria were used in determining limits. In the six earthquakes examined, we correlated the outermost landslide limits with peak ground accelerations (PGAs) from ShakeMap models of each earthquake. For the four earthquakes studied by field investigation, the minimum PGA values associated with farthest landslide limits ranged from 0.02g to 0.08g. The range for the two earthquakes investigated using aerial‐photographic interpretations was 0.05–0.11g. Although PGA values at landslide limits depend on several factors, including material strength, topographic amplification, and hydrologic conditions, these values provide an empirically useful lower limiting range of PGA needed to trigger the smallest failures on very susceptible slopes. In a well‐recorded earthquake, this PGA range can be used to identify an outer boundary within which we might expect to find landsliding; in earthquakes that are not well recorded, mapping the outermost landslide limits provides a useful clue about ground‐motion levels at the mapped limits.

Earthquake shaking hazard estimates and exposure changes in the conterminous United States

USGS Publications Warehouse

Jaiswal, Kishor S.; Petersen, Mark D.; Rukstales, Kenneth S.; Leith, William S.

2015-01-01

A large portion of the population of the United States lives in areas vulnerable to earthquake hazards. This investigation aims to quantify population and infrastructure exposure within the conterminous U.S. that are subjected to varying levels of earthquake ground motions by systematically analyzing the last four cycles of the U.S. Geological Survey's (USGS) National Seismic Hazard Models (published in 1996, 2002, 2008 and 2014). Using the 2013 LandScan data, we estimate the numbers of people who are exposed to potentially damaging ground motions (peak ground accelerations at or above 0.1g). At least 28 million (~9% of the total population) may experience 0.1g level of shaking at relatively frequent intervals (annual rate of 1 in 72 years or 50% probability of exceedance (PE) in 50 years), 57 million (~18% of the total population) may experience this level of shaking at moderately frequent intervals (annual rate of 1 in 475 years or 10% PE in 50 years), and 143 million (~46% of the total population) may experience such shaking at relatively infrequent intervals (annual rate of 1 in 2,475 years or 2% PE in 50 years). We also show that there is a significant number of critical infrastructure facilities located in high earthquake-hazard areas (Modified Mercalli Intensity ≥ VII with moderately frequent recurrence interval).

Implications of the Mw9.0 Tohoku-Oki earthquake for ground motion scaling with source, path, and site parameters

USGS Publications Warehouse

Stewart, Jonathan P.; Midorikawa, Saburoh; Graves, Robert W.; Khodaverdi, Khatareh; Kishida, Tadahiro; Miura, Hiroyuki; Bozorgnia, Yousef; Campbell, Kenneth W.

2013-01-01

The Mw9.0 Tohoku-oki Japan earthquake produced approximately 2,000 ground motion recordings. We consider 1,238 three-component accelerograms corrected with component-specific low-cut filters. The recordings have rupture distances between 44 km and 1,000 km, time-averaged shear wave velocities of VS30 = 90 m/s to 1,900 m/s, and usable response spectral periods of 0.01 sec to >10 sec. The data support the notion that the increase of ground motions with magnitude saturates at large magnitudes. High-frequency ground motions demonstrate faster attenuation with distance in backarc than in forearc regions, which is only captured by one of the four considered ground motion prediction equations for subduction earthquakes. Recordings within 100 km of the fault are used to estimate event terms, which are generally positive (indicating model underprediction) at short periods and zero or negative (overprediction) at long periods. We find site amplification to scale minimally with VS30 at high frequencies, in contrast with other active tectonic regions, but to scale strongly with VS30 at low frequencies.

Modified Mercalli Intensity for scenario earthquakes in Evansville, Indiana

USGS Publications Warehouse

Cramer, Chris; Haase, Jennifer; Boyd, Oliver

2012-01-01

Evansville, Indiana, has experienced minor damage from earthquakes several times in the past 200 years. Because of this history and the fact that Evansville is close to the Wabash Valley and New Madrid seismic zones, there is concern about the hazards from earthquakes. Earthquakes currently cannot be predicted, but scientists can estimate how strongly the ground is likely to shake as a result of an earthquake. Earthquake-hazard maps provide one way of conveying such estimates of strong ground shaking and will help the region prepare for future earthquakes and reduce earthquake-caused losses.

3D ground‐motion simulations of Mw 7 earthquakes on the Salt Lake City segment of the Wasatch fault zone: Variability of long‐period (T≥1  s) ground motions and sensitivity to kinematic rupture parameters

USGS Publications Warehouse

Moschetti, Morgan P.; Hartzell, Stephen; Ramirez-Guzman, Leonardo; Frankel, Arthur; Angster, Stephen J.; Stephenson, William J.

2017-01-01

We examine the variability of long‐period (T≥1  s) earthquake ground motions from 3D simulations of Mw 7 earthquakes on the Salt Lake City segment of the Wasatch fault zone, Utah, from a set of 96 rupture models with varying slip distributions, rupture speeds, slip velocities, and hypocenter locations. Earthquake ruptures were prescribed on a 3D fault representation that satisfies geologic constraints and maintained distinct strands for the Warm Springs and for the East Bench and Cottonwood faults. Response spectral accelerations (SA; 1.5–10 s; 5% damping) were measured, and average distance scaling was well fit by a simple functional form that depends on the near‐source intensity level SA0(T) and a corner distance Rc:SA(R,T)=SA0(T)(1+(R/Rc))−1. Period‐dependent hanging‐wall effects manifested and increased the ground motions by factors of about 2–3, though the effects appeared partially attributable to differences in shallow site response for sites on the hanging wall and footwall of the fault. Comparisons with modern ground‐motion prediction equations (GMPEs) found that the simulated ground motions were generally consistent, except within deep sedimentary basins, where simulated ground motions were greatly underpredicted. Ground‐motion variability exhibited strong lateral variations and, at some sites, exceeded the ground‐motion variability indicated by GMPEs. The effects on the ground motions of changing the values of the five kinematic rupture parameters can largely be explained by three predominant factors: distance to high‐slip subevents, dynamic stress drop, and changes in the contributions from directivity. These results emphasize the need for further characterization of the underlying distributions and covariances of the kinematic rupture parameters used in 3D ground‐motion simulations employed in probabilistic seismic‐hazard analyses.

Real-time neural network earthquake profile predictor

DOEpatents

Leach, R.R.; Dowla, F.U.

1996-02-06

A neural network has been developed that uses first-arrival energy to predict the characteristics of impending earthquake seismograph signals. The propagation of ground motion energy through the earth is a highly nonlinear function. This is due to different forms of ground motion as well as to changes in the elastic properties of the media throughout the propagation path. The neural network is trained using seismogram data from earthquakes. Presented with a previously unseen earthquake, the neural network produces a profile of the complete earthquake signal using data from the first seconds of the signal. This offers a significant advance in the real-time monitoring, warning, and subsequent hazard minimization of catastrophic ground motion. 17 figs.

Real-time neural network earthquake profile predictor

DOEpatents

Leach, Richard R.; Dowla, Farid U.

1996-01-01

A neural network has been developed that uses first-arrival energy to predict the characteristics of impending earthquake seismograph signals. The propagation of ground motion energy through the earth is a highly nonlinear function. This is due to different forms of ground motion as well as to changes in the elastic properties of the media throughout the propagation path. The neural network is trained using seismogram data from earthquakes. Presented with a previously unseen earthquake, the neural network produces a profile of the complete earthquake signal using data from the first seconds of the signal. This offers a significant advance in the real-time monitoring, warning, and subsequent hazard minimization of catastrophic ground motion.

Building damage concentrated in Longtoushan town during the 2014 Ms. 6.5 Ludian earthquake, Yunnan, China: examination of cause and implications based on ground motion and vulnerability analyses

NASA Astrophysics Data System (ADS)

Wang, Xin; Kurahashi, Susumu; Wu, Hao; Si, Hongjun; Ma, Qiang; Dang, Ji; Tao, Dongwang; Feng, Jiwei; Irikura, Kojiro

2017-09-01

Though the 2014 Ludian Earthquake had only a moderate magnitude (Ms 6.5), high-level ground motions of almost 1 g occurred at Longtoushan Town (seismic station 53LLT), which located near the intersection of a conjugate-shaped seismogenic fault. The building damages on the pluvial fan and the river terrace at Longtoushan was clearly different. In order to examine the generation of the large acceleration at 53LLT, the focal mechanisms and the rupture processes of the conjugate-shaped seismogenic fault were determined. We found that there were two continuous impulsive waves in the records of 53LLT that were generated from two different faults, the Baogunao fault and the Xiaohe fault, respectively. Site effects on the pluvial fan and the river terrace at Longtoushan Town and their relations to different building damages were examined. We found that the predominant period at the pluvial fan was about 0.25 s, close to the fundamental natural period of multi-story confined masonry buildings. Ground motions on the pluvial fan and the river terrace were simulated through convolving synthesized bedrock motions with the transfer functions, which were analyzed using the one-dimensional underground velocity structures identified from H/V spectral ratios of ambient noise. Building collapse ratios (CRs) are estimated based on the vulnerability function of the 2008 Wenchuan Earthquake and are compared with the observed values. We found that the observed building CRs on the pluvial fan are much higher than the estimated values. High-level ground shaking that is far beyond the design level was a reason for serious building damage.

Dynamic Parameters of the 2015 Nepal Gorkha Mw7.8 Earthquake Constrained by Multi-observations

NASA Astrophysics Data System (ADS)

Weng, H.; Yang, H.

2017-12-01

Dynamic rupture model can provide much detailed insights into rupture physics that is capable of assessing future seismic risk. Many studies have attempted to constrain the slip-weakening distance, an important parameter controlling friction behavior of rock, for several earthquakes based on dynamic models, kinematic models, and direct estimations from near-field ground motion. However, large uncertainties of the values of the slip-weakening distance still remain, mostly because of the intrinsic trade-offs between the slip-weakening distance and fault strength. Here we use a spontaneously dynamic rupture model to constrain the frictional parameters of the 25 April 2015 Mw7.8 Nepal earthquake, by combining with multiple seismic observations such as high-rate cGPS data, strong motion data, and kinematic source models. With numerous tests we find the trade-off patterns of final slip, rupture speed, static GPS ground displacements, and dynamic ground waveforms are quite different. Combining all the seismic constraints we can conclude a robust solution without a substantial trade-off of average slip-weakening distance, 0.6 m, in contrast to previous kinematical estimation of 5 m. To our best knowledge, this is the first time to robustly determine the slip-weakening distance on seismogenic fault from seismic observations. The well-constrained frictional parameters may be used for future dynamic models to assess seismic hazard, such as estimating the peak ground acceleration (PGA) etc. Similar approach could also be conducted for other great earthquakes, enabling broad estimations of the dynamic parameters in global perspectives that can better reveal the intrinsic physics of earthquakes.

Numerical Simulation of Strong Ground Motion at Mexico City:A Hybrid Approach for Efficient Evaluation of Site Amplification and Path Effects for Different Types of Earthquakes

NASA Astrophysics Data System (ADS)

Cruz, H.; Furumura, T.; Chavez-Garcia, F. J.

2002-12-01

The estimation of scenarios of the strong ground motions caused by future great earthquakes is an important problem in strong motion seismology. This was pointed out by the great 1985 Michoacan earthquake, which caused a great damage in Mexico City, 300 km away from the epicenter. Since the seismic wavefield is characterized by the source, path and site effects, the pattern of strong motion damage from different types of earthquakes should differ significantly. In this study, the scenarios for intermediate-depth normal-faulting, shallow-interplate thrust faulting, and crustal earthquakes have been estimated using a hybrid simulation technique. The character of the seismic wavefield propagating from the source to Mexico City for each earthquake was first calculated using the pseudospectral method for 2D SH waves. The site amplifications in the shallow structure of Mexico City are then calculated using the multiple SH wave reverberation theory. The scenarios of maximum ground motion for both inslab and interplate earthquakes obtained by the simulation show a good agreement with the observations. This indicates the effectiveness of the hybrid simulation approach to investigate the strong motion damage for future earthquakes.

North Anna Nuclear Power Plant Strong Motion Records of the Mineral, Virginia Earthquake of August 23, 2011

NASA Astrophysics Data System (ADS)

Graizer, V.

2012-12-01

The MW 5.8 Mineral, Virginia earthquake was recorded at a relatively short epicentral distance of about 18 km at the North Anna Nuclear Power Plant (NPP) by the SMA-3 magnetic tape digital accelerographs installed inside the plant's containment at the foundation and deck levels. The North Anna NPP is operated by the Virginia Electric and Power Company (VEPCO) and has two pressurized water reactors (PWR) units that began operation in 1978 and 1980, respectively. Following the earthquake, both units were safely shutdown. The strong-motion records were processed to get velocity, displacement, Fourier and 5% damped response spectra. The basemat record demonstrated relatively high amplitudes of acceleration of 0.26 g and velocity of 13.8 cm/sec with a relatively short duration of strong motion of 2-3 sec. Recorded 5% damped Response Spectra exceed Design Basis Earthquake for the existing Units 1 and 2, while comprehensive plant inspections performed by VEPCO and U.S. Nuclear Regulatory Commission have concluded that the damage to the plant was minimal not affecting any structures and equipment significant to plant operation. This can be explained in part by short duration of the earthquake ground motion at the plant. The North Anna NPP did not have free-field strong motion instrumentation at the time of the earthquake. Since the containment is founded on rock there is a tendency to consider basemat record as an approximation of the free-field recording. However, comparisons of deck and basemat records demonstrate that the basemat recording is also affected by structural resonance frequencies higher than 3 Hz. Structural resonances in the frequency range of 3-4 Hz can at least partially explain significant exceedance of observed motions relative to ground motion calculated using ground motion prediction equations.cceleration, velocity and displacement at the North Anna NPP basemat level. Amplitudes of acceleration, velocity and displacement at basemat and deck levels

Multi-sensor Integration of Space and Ground Observations of Pre-earthquake Anomalies Associated with M6.0, August 24, 2014 Napa, California

NASA Astrophysics Data System (ADS)

Ouzounov, Dimitar; Tramutoli, Valerio; Pulinets, Sergey; Liu, Tiger; Filizzola, Carolina; Genzano, Nicola; Lisi, Mariano; Petrov, Leonid; Kafatos, Menas

2015-04-01

We integrate multiple space-born and ground sensors for monitoring pre-earthquake geophysical anomalies that can provide significant early notification for earthquakes higher than M5.5 worldwide. The latest M6.0 event of August 24, 2014 in South Napa, California generated pre-earthquake signatures during our outgoing tests for California, and an experimental warning was documented about 17 days in advance. We process in controlled environment different satellite and ground data for California (and several other test areas) by using: a) data from the NPOES sensors recording OLR (Outgoing Longwave Radiation) in the infrared; b) 2/GNSS, FORMOSAT (GPS/TEC); c) Earth Observing System assimilation models from NASA; d) ground-based gas observations and meteorological data; e) TIR (Thermal Infrared) data from geostationary satellite (GOES). On Aug 4th, we detected (prospectively) a large anomaly of OLR transient field at the TOA over Northern California. The location was shifted in the northeast direction about 150 km from the Aug 23rd epicentral area. Compared to the reference field of August 2004 to 2014 the hotspot anomaly was the largest energy flux anomaly over the entire continental United States at this time. Based on the temporal and spatial estimates of the anomaly, on August 4th we issued an internal warning for a M5.5+ earthquake in Northern California within the next 1-4 weeks. TIR retrospective analysis showed significant (spatially extended and temporally persistent) sequences of TIR anomalies starting August 1st just in the future epicenter area and approximately in the same area affected by OLR anomalies in the following days. GPS/TEC retrospective analysis based on GIM and TGIM products show anomalies TEC variations 1-3 days, over region north form the Napa earthquake epicenter. The calculated index of atmospheric chemical potential based on the NASA numerical Assimilation weather model GEOS5 indicates for abnormal variations near the epicentral area days

Spatial Based Integrated Assessment of Bedrock and Ground Motions, Fault Offsets, and Their Effects for the October-November 2002 Earthquake Sequence on the Denali Fault, Alaska

NASA Astrophysics Data System (ADS)

Vinson, T. S.; Carlson, R.; Hansen, R.; Hulsey, L.; Ma, J.; White, D.; Barnes, D.; Shur, Y.

2003-12-01

A National Science Foundation (NSF) Small Grant Exploratory Research Grant was awarded to the University of Alaska Fairbanks to archive bedrock and ground motions and fault offsets and their effects for the October-November 2002 earthquake sequence on the Denali Fault, Alaska. The scope of work included the accumulation of all strong motion records, satellite imagery, satellite remote sensing data, aerial and ground photographs, and structural response (both measured and anecdotal) that would be useful to achieve the objective. Several interesting data sets were archived including ice cover, lateral movement of stream channels, landslides, avalanches, glacial fracturing, "felt" ground motions, and changes in water quantity and quality. The data sources may be spatially integrated to provide a comprehensive assessment of the bedrock and ground motions and fault offsets for the October-November 2002 earthquake sequence. In the aftermath of the October-November 2002 earthquake sequence on the Denali fault, the Alaskan engineering community expressed a strong interest to understand why their structures and infrastructure were not substantially damaged by the ground motions they experienced during the October-November 2002 Earthquake Sequence on the Denali Fault. The research work proposed under this NSF Grant is a necessary prerequisite to this understanding. Furthermore, the proposed work will facilitate a comparison of Denali events with the Loma Prieta and recent Kocelli and Dozce events in Turkey, all of which were associated with strike-slip faulting. Finally, the spatially integrated data will provide the basis for research work that is truly innovative. For example, is may be possible to predict the observed (1) landsliding and avalanches, (2) changes in water quantity and quality, (3) glacial fracturing, and (4) the widespread liquefaction and lateral spreading, which occurred along the Tok cutoff and Northway airport, with the bedrock and ground motions and

Modeling of a historical earthquake in Erzincan, Turkey (Ms 7.8, in 1939) using regional seismological information obtained from a recent event

NASA Astrophysics Data System (ADS)

Karimzadeh, Shaghayegh; Askan, Aysegul

2018-04-01

Located within a basin structure, at the conjunction of North East Anatolian, North Anatolian and Ovacik Faults, Erzincan city center (Turkey) is one of the most hazardous regions in the world. Combination of the seismotectonic and geological settings of the region has resulted in series of significant seismic activities including the 1939 (Ms 7.8) as well as the 1992 (Mw = 6.6) earthquakes. The devastative 1939 earthquake occurred in the pre-instrumental era in the region with no available local seismograms. Thus, a limited number of studies exist on that earthquake. However, the 1992 event, despite the sparse local network at that time, has been studied extensively. This study aims to simulate the 1939 Erzincan earthquake using available regional seismic and geological parameters. Despite several uncertainties involved, such an effort to quantitatively model the 1939 earthquake is promising, given the historical reports of extensive damage and fatalities in the area. The results of this study are expressed in terms of anticipated acceleration time histories at certain locations, spatial distribution of selected ground motion parameters and felt intensity maps in the region. Simulated motions are first compared against empirical ground motion prediction equations derived with both local and global datasets. Next, anticipated intensity maps of the 1939 earthquake are obtained using local correlations between peak ground motion parameters and felt intensity values. Comparisons of the estimated intensity distributions with the corresponding observed intensities indicate a reasonable modeling of the 1939 earthquake.

Strong motion simulation by the composite source modeling: A case study of 1679 M8.0 Sanhe-Pinggu earthquake

NASA Astrophysics Data System (ADS)

Liu, Bo-Yan; Shi, Bao-Ping; Zhang, Jian

2007-05-01

In this study, a composite source model has been used to calculate the realistic strong ground motions in Beijing area, caused by 1679 M S8.0 earthquake in Sanhe-Pinggu. The results could provide us the useful physical parameters for the future seismic hazard analysis in this area. Considering the regional geological/geophysical background, we simulated the scenario earthquake with an associated ground motions in the area ranging from 39.3°N to 41.1°N in latitude and from 115.35°E to 117.55°E in longitude. Some of the key factors which could influence the characteristics of strong ground motion have been discussed, and the resultant peak ground acceleration (PGA) distribution and the peak ground velocity (PGV) distribution around Beijing area also have been made as well. A comparison of the simulated result with the results derived from the attenuation relation has been made, and a sufficient discussion about the advantages and disadvantages of composite source model also has been given in this study. The numerical results, such as the PGA, PGV, peak ground displacement (PGD), and the three-component time-histories developed for Beijing area, have a potential application in earthquake engineering field and building code design, especially for the evaluation of critical constructions, government decision making and the seismic hazard assessment by financial/insurance companies.

Do moderate magnitude earthquakes generate seismically induced ground effects? The case study of the M w = 5.16, 29th December 2013 Matese earthquake (southern Apennines, Italy)

NASA Astrophysics Data System (ADS)

Valente, Ettore; Ascione, A.; Ciotoli, G.; Cozzolino, M.; Porfido, S.; Sciarra, A.

2018-03-01

Seismically induced ground effects characterize moderate to high magnitude seismic events, whereas they are not so common during seismic sequences of low to moderate magnitude. A low to moderate magnitude seismic sequence with a M w = 5.16 ± 0.07 main event occurred from December 2013 to February 2014 in the Matese ridge area, in the southern Apennines mountain chain. In the epicentral area of the M w = 5.16 main event, which happened on December 29th 2013 in the southeastern part of the Matese ridge, field surveys combined with information from local people and reports allowed the recognition of several earthquake-induced ground effects. Such ground effects include landslides, hydrological variations in local springs, gas flux, and a flame that was observed around the main shock epicentre. A coseismic rupture was identified in the SW fault scarp of a small-sized intermontane basin (Mt. Airola basin). To detect the nature of the coseismic rupture, detail scale geological and geomorphological investigations, combined with geoelectrical and soil gas prospections, were carried out. Such a multidisciplinary study, besides allowing reconstruction of the surface and subsurface architecture of the Mt. Airola basin, and suggesting the occurrence of an active fault at the SW boundary of such basin, points to the gravitational nature of the coseismic ground rupture. Based on typology and spatial distribution of the ground effects, an intensity I = VII-VIII is estimated for the M w = 5.16 earthquake according to the ESI-07 scale, which affected an area of at least 90 km2.

Prediction of the area affected by earthquake-induced landsliding based on seismological parameters

NASA Astrophysics Data System (ADS)

Marc, Odin; Meunier, Patrick; Hovius, Niels

2017-07-01

We present an analytical, seismologically consistent expression for the surface area of the region within which most landslides triggered by an earthquake are located (landslide distribution area). This expression is based on scaling laws relating seismic moment, source depth, and focal mechanism with ground shaking and fault rupture length and assumes a globally constant threshold of acceleration for onset of systematic mass wasting. The seismological assumptions are identical to those recently used to propose a seismologically consistent expression for the total volume and area of landslides triggered by an earthquake. To test the accuracy of the model we gathered geophysical information and estimates of the landslide distribution area for 83 earthquakes. To reduce uncertainties and inconsistencies in the estimation of the landslide distribution area, we propose an objective definition based on the shortest distance from the seismic wave emission line containing 95 % of the total landslide area. Without any empirical calibration the model explains 56 % of the variance in our dataset, and predicts 35 to 49 out of 83 cases within a factor of 2, depending on how we account for uncertainties on the seismic source depth. For most cases with comprehensive landslide inventories we show that our prediction compares well with the smallest region around the fault containing 95 % of the total landslide area. Aspects ignored by the model that could explain the residuals include local variations of the threshold of acceleration and processes modulating the surface ground shaking, such as the distribution of seismic energy release on the fault plane, the dynamic stress drop, and rupture directivity. Nevertheless, its simplicity and first-order accuracy suggest that the model can yield plausible and useful estimates of the landslide distribution area in near-real time, with earthquake parameters issued by standard detection routines.

A Mw 6.3 earthquake scenario in the city of Nice (southeast France): ground motion simulations

NASA Astrophysics Data System (ADS)

Salichon, Jérome; Kohrs-Sansorny, Carine; Bertrand, Etienne; Courboulex, Françoise

2010-07-01

The southern Alps-Ligurian basin junction is one of the most seismically active zone of the western Europe. A constant microseismicity and moderate size events (3.5 < M < 5) are regularly recorded. The last reported historical event took place in February 1887 and reached an estimated magnitude between 6 and 6.5, causing human losses and extensive damages (intensity X, Medvedev-Sponheuer-Karnik). Such an event, occurring nowadays, could have critical consequences given the high density of population living on the French and Italian Riviera. We study the case of an offshore Mw 6.3 earthquake located at the place where two moderate size events (Mw 4.5) occurred recently and where a morphotectonic feature has been detected by a bathymetric survey. We used a stochastic empirical Green’s functions (EGFs) summation method to produce a population of realistic accelerograms on rock and soil sites in the city of Nice. The ground motion simulations are calibrated on a rock site with a set of ground motion prediction equations (GMPEs) in order to estimate a reasonable stress-drop ratio between the February 25th, 2001, Mw 4.5, event taken as an EGF and the target earthquake. Our results show that the combination of the GMPEs and EGF techniques is an interesting tool for site-specific strong ground motion estimation.

A landslide susceptibility prediction on a sample slope in Kathmandu Nepal associated with the 2015's Gorkha Earthquake

NASA Astrophysics Data System (ADS)

Kubota, Tetsuya; Prasad Paudel, Prem

2016-04-01

In 2013, some landslides induced by heavy rainfalls occurred in southern part of Kathmandu, Nepal which is located southern suburb of Kathmandu, the capital. These landslide slopes hit by the strong Gorkha Earthquake in April 2015 and seemed to destabilize again. Hereby, to clarify their susceptibility of landslide in the earthquake, one of these landslide slopes was analyzed its slope stability by CSSDP (Critical Slip Surface analysis by Dynamic Programming based on limit equilibrium method, especially Janbu method) against slope failure with various seismic acceleration observed around Kathmandu in the Gorkha Earthquake. The CSSDP can detect the landslide slip surface which has minimum Fs (factor of safety) automatically using dynamic programming theory. The geology in this area mainly consists of fragile schist and it is prone to landslide occurrence. Field survey was conducted to obtain topological data such as ground surface and slip surface cross section. Soil parameters obtained by geotechnical tests with field sampling were applied. Consequently, the slope has distinctive characteristics followings in terms of slope stability: (1) With heavy rainfall, it collapsed and had a factor of safety Fs <1.0 (0.654 or more). (2) With seismic acceleration of 0.15G (147gal) observed around Kathmandu, it has Fs=1.34. (3) With possible local seismic acceleration of 0.35G (343gal) estimated at Kathmandu, it has Fs=0.989. If it were very shallow landslide and covered with cedars, it could have Fs =1.055 due to root reinforcement effect to the soil strength. (4) Without seismic acceleration and with no rainfall condition, it has Fs=1.75. These results can explain the real landslide occurrence in this area with the maximum seismic acceleration estimated as 0.15G in the vicinity of Kathmandu by the Gorkha Earthquake. Therefore, these results indicate landslide susceptibility of the slopes in this area with strong earthquake. In this situation, it is possible to predict

Ground Motion Prediction Model Using Artificial Neural Network

NASA Astrophysics Data System (ADS)

Dhanya, J.; Raghukanth, S. T. G.

2018-03-01

This article focuses on developing a ground motion prediction equation based on artificial neural network (ANN) technique for shallow crustal earthquakes. A hybrid technique combining genetic algorithm and Levenberg-Marquardt technique is used for training the model. The present model is developed to predict peak ground velocity, and 5% damped spectral acceleration. The input parameters for the prediction are moment magnitude ( M w), closest distance to rupture plane ( R rup), shear wave velocity in the region ( V s30) and focal mechanism ( F). A total of 13,552 ground motion records from 288 earthquakes provided by the updated NGA-West2 database released by Pacific Engineering Research Center are utilized to develop the model. The ANN architecture considered for the model consists of 192 unknowns including weights and biases of all the interconnected nodes. The performance of the model is observed to be within the prescribed error limits. In addition, the results from the study are found to be comparable with the existing relations in the global database. The developed model is further demonstrated by estimating site-specific response spectra for Shimla city located in Himalayan region.

Strong-motion observations of the M 7.8 Gorkha, Nepal, earthquake sequence and development of the N-shake strong-motion network

USGS Publications Warehouse

Dixit, Amod; Ringler, Adam; Sumy, Danielle F.; Cochran, Elizabeth S.; Hough, Susan E.; Martin, Stacey; Gibbons, Steven; Luetgert, James H.; Galetzka, John; Shrestha, Surya; Rajaure, Sudhir; McNamara, Daniel E.

2015-01-01

We present and describe strong-motion data observations from the 2015 M 7.8 Gorkha, Nepal, earthquake sequence collected using existing and new Quake-Catcher Network (QCN) and U.S. Geological Survey NetQuakes sensors located in the Kathmandu Valley. A comparison of QCN data with waveforms recorded by a conventional strong-motion (NetQuakes) instrument validates the QCN data. We present preliminary analysis of spectral accelerations, and peak ground acceleration and velocity for earthquakes up to M 7.3 from the QCN stations, as well as preliminary analysis of the mainshock recording from the NetQuakes station. We show that mainshock peak accelerations were lower than expected and conclude the Kathmandu Valley experienced a pervasively nonlinear response during the mainshock. Phase picks from the QCN and NetQuakes data are also used to improve aftershock locations. This study confirms the utility of QCN instruments to contribute to ground-motion investigations and aftershock response in regions where conventional instrumentation and open-access seismic data are limited. Initial pilot installations of QCN instruments in 2014 are now being expanded to create the Nepal–Shaking Hazard Assessment for Kathmandu and its Environment (N-SHAKE) network.

The Mw6.0 24 August 2014 South Napa earthquake

USGS Publications Warehouse

Brocher, Thomas M.; Baltay, Annemarie S.; Hardebeck, Jeanne L.; Pollitz, Fred F.; Murray, Jessica R.; Llenos, Andrea L.; Schwartz, David P.; Blair, James Luke; Ponti, Daniel J.; Lienkaemper, James J.; Langenheim, V.E.; Dawson, Timothy E.; Hudnut, Kenneth W.; Shelly, David R.; Dreger, Douglas S.; Boatwright, John; Aagaard, Brad T.; Wald, David J.; Allen, Richard M.; Barnhart, William D.; Knudsen, Keith L.; Brooks, Benjamin A.; Scharer, Katherine M.

2015-01-01

The Mw 6.0 South Napa earthquake, which occurred at 10:20 UTC 24 August 2014 was the largest earthquake to strike the greater San Francisco Bay area since the Mw 6.9 1989 Loma Prieta earthquake. The rupture from this right‐lateral earthquake propagated mostly unilaterally to the north and up‐dip, directing the strongest shaking toward the city of Napa, where peak ground accelerations (PGAs) between 45%g and 61%g were recorded and modified Mercalli intensities (MMIs) of VII–VIII were reported. Tectonic surface rupture with dextral slip of up to 46 cm was observed on a 12.5 km long segment, some of which was along a previously mapped strand of the West Napa fault system, although the rupture extended to the north of the mapped Quaternary strand. Modeling of seismic and geodetic data suggests an average coseismic slip of 50 cm, with a maximum slip of about 1 m at depths of 10–11 km. We observed up to 35 cm of afterslip along the surface trace in the week following the mainshock, primarily along the southern half of the surface rupture that experienced relatively little coseismic offset. Relocation of the sparse aftershock sequence suggests en echelon southwest‐ and northeast‐dipping fault planes, reflective of the complex fault geometry in this region. The Napa basin and historic and late Holocene alluvial flood deposits in downtown Napa amplified the ground motions there. Few ground failures were mapped, reflecting the dry season (as well as a persistent drought that had lowered the groundwater table) and the short duration of strong shaking in the epicentral area.

Performance of Irikura's Recipe Rupture Model Generator in Earthquake Ground Motion Simulations as Implemented in the Graves and Pitarka Hybrid Approach.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pitarka, A.

We analyzed the performance of the Irikura and Miyake (2011) (IM2011) asperity-­ based kinematic rupture model generator, as implemented in the hybrid broadband ground-­motion simulation methodology of Graves and Pitarka (2010), for simulating ground motion from crustal earthquakes of intermediate size. The primary objective of our study is to investigate the transportability of IM2011 into the framework used by the Southern California Earthquake Center broadband simulation platform. In our analysis, we performed broadband (0 -­ 20Hz) ground motion simulations for a suite of M6.7 crustal scenario earthquakes in a hard rock seismic velocity structure using rupture models produced with bothmore » IM2011 and the rupture generation method of Graves and Pitarka (2016) (GP2016). The level of simulated ground motions for the two approaches compare favorably with median estimates obtained from the 2014 Next Generation Attenuation-­West2 Project (NGA-­West2) ground-­motion prediction equations (GMPEs) over the frequency band 0.1–10 Hz and for distances out to 22 km from the fault. We also found that, compared to GP2016, IM2011 generates ground motion with larger variability, particularly at near-­fault distances (<12km) and at long periods (>1s). For this specific scenario, the largest systematic difference in ground motion level for the two approaches occurs in the period band 1 – 3 sec where the IM2011 motions are about 20 – 30% lower than those for GP2016. We found that increasing the rupture speed by 20% on the asperities in IM2011 produced ground motions in the 1 – 3 second bandwidth that are in much closer agreement with the GMPE medians and similar to those obtained with GP2016. The potential implications of this modification for other rupture mechanisms and magnitudes are not yet fully understood, and this topic is the subject of ongoing study.« less

Liquefaction evidence for the strength of ground motions resulting from Late Holocene Cascadia subduction earthquakes, with emphasis on the event of 1700 A.D.

USGS Publications Warehouse

Obermeier, S.F.; Dickenson, S.E.

2000-01-01

During the past decade, paleoseismic studies done by many researchers in the coastal regions of the Pacific Northwest have shown that regional downdropping and subsequent tsunami inundation occurred in response to a major earthquake along the Cascadia subduction zone. This earthquake occurred almost certainly in 1700 A.D., and is believed by many to have been of M 8.5-9 or perhaps larger. In order to characterize the severity of ground motions from this earthquake, we report on a field search and analysis of seismically induced liquefaction features. The search was conducted chiefly along the banks of islands in the lowermost Columbia River of Oregon and Washington and in stream banks along smaller rivers throughout southwestern Washington. To a lesser extent, the investigation included rivers in central Oregon. Numerous small- to moderate-sized liquefaction features from the earthquake of 1700 A.D. were found in some regions, but there was a notable lack of liquefaction features in others. The regional distribution of liquefaction features is evaluated as a function of geologic and geotechnical factors in different field settings near the coast. Our use of widely different field settings, each in which we independently assess the strength of shaking and arrive at the same conclusion, enhances the credibility of our interpretations. Our regional inventory of liquefaction features and preliminary geotechnical analysis of liquefaction potential provide substantial evidence for only moderate levels of ground shaking in coastal Washington and Oregon during the subduction earthquake of 1700 A.D. Additionally, it appears that a similar conclusion can be reached for an earlier subduction earthquake that occurred within the past 1100 years, which also has been characterized by others as being M 8 or greater. On the basis of more limited data for older events collected in our regional study, it appears that seismic shaking has been no stronger throughout Holocene time. Our

The threat of silent earthquakes

USGS Publications Warehouse

Cervelli, Peter

2004-01-01

Not all earthquakes shake the ground. The so-called silent types are forcing scientists to rethink their understanding of the way quake-prone faults behave. In rare instances, silent earthquakes that occur along the flakes of seaside volcanoes may cascade into monstrous landslides that crash into the sea and trigger towering tsunamis. Silent earthquakes that take place within fault zones created by one tectonic plate diving under another may increase the chance of ground-shaking shocks. In other locations, however, silent slip may decrease the likelihood of destructive quakes, because they release stress along faults that might otherwise seem ready to snap.

Slip reactivation during the 2011 Tohoku earthquake: Dynamic rupture and ground motion simulations

NASA Astrophysics Data System (ADS)

Galvez, P.; Dalguer, L. A.

2013-12-01

The 2011 Mw9 Tohoku earthquake generated such as vast geophysical data that allows studying with an unprecedented resolution the spatial-temporal evolution of the rupture process of a mega thrust event. Joint source inversion of teleseismic, near-source strong motion and coseismic geodetic data , e.g [Lee et. al, 2011], reveal an evidence of slip reactivation process at areas of very large slip. The slip of snapshots of this source model shows that after about 40 seconds the big patch above to the hypocenter experienced an additional push of the slip (reactivation) towards the trench. These two possible repeating slip exhibited by source inversions can create two waveform envelops well distinguished in the ground motion pattern. In fact seismograms of the KiK-Net Japanese network contained this pattern. For instance a seismic station around Miyagi (MYGH10) has two main wavefronts separated between them by 40 seconds. A possible physical mechanism to explain the slip reactivation could be a thermal pressurization process occurring in the fault zone. In fact, Kanamori & Heaton, (2000) proposed that for large earthquakes frictional melting and fluid pressurization can play a key role of the rupture dynamics of giant earthquakes. If fluid exists in a fault zone, an increase of temperature can rise up the pore pressure enough to significantly reduce the frictional strength. Therefore, during a large earthquake the areas of big slip persuading strong thermal pressurization may result in a second drop of the frictional strength after reaching a certain value of slip. Following this principle, we adopt for slip weakening friction law and prescribe a certain maximum slip after which the friction coefficient linearly drops down again. The implementation of this friction law has been done in the latest unstructured spectral element code SPECFEM3D, Peter et. al. (2012). The non-planar subduction interface has been taken into account and place on it a big asperity patch inside

Using Simulated Ground Motions to Constrain Near-Source Ground Motion Prediction Equations in Areas Experiencing Induced Seismicity

NASA Astrophysics Data System (ADS)

Bydlon, S. A.; Dunham, E. M.

2016-12-01

Recent increases in seismic activity in historically quiescent areas such as Oklahoma, Texas, and Arkansas, including large, potentially induced events such as the 2011 Mw 5.6 Prague, OK, earthquake, have spurred the need for investigation into expected ground motions associated with these seismic sources. The neoteric nature of this seismicity increase corresponds to a scarcity of ground motion recordings within 50 km of earthquakes Mw 3.0 and greater, with increasing scarcity at larger magnitudes. Gathering additional near-source ground motion data will help better constraints on regional ground motion prediction equations (GMPEs) and will happen over time, but this leaves open the possibility of damaging earthquakes occurring before potential ground shaking and seismic hazard in these areas are properly understood. To aid the effort of constraining near-source GMPEs associated with induced seismicity, we integrate synthetic ground motion data from simulated earthquakes into the process. Using the dynamic rupture and seismic wave propagation code waveqlab3d, we perform verification and validation exercises intended to establish confidence in simulated ground motions for use in constraining GMPEs. We verify the accuracy of our ground motion simulator by performing the PEER/SCEC layer-over-halfspace comparison problem LOH.1 Validation exercises to ensure that we are synthesizing realistic ground motion data include comparisons to recorded ground motions for specific earthquakes in target areas of Oklahoma between Mw 3.0 and 4.0. Using a 3D velocity structure that includes a 1D structure with additional small-scale heterogeneity, the properties of which are based on well-log data from Oklahoma, we perform ground motion simulations of small (Mw 3.0 - 4.0) earthquakes using point moment tensor sources. We use the resulting synthetic ground motion data to develop GMPEs for small earthquakes in Oklahoma. Preliminary results indicate that ground motions can be amplified

Outline of the 2016 Kumamoto, Japan, Earthquakes and lessons for a large urban earthquake in Tokyo Metropolitan area

NASA Astrophysics Data System (ADS)

Hirata, N.

2016-12-01

A series of devastating earthquakes hit Kumamoto districts in Kyushu, Japan, in April, 2016. The M6.5 event occurred at 21:26 on April 14th (JST) and, 28 hours later, the M7.3 event occurred at 01:25 on April 17th (JST) at almost the same location with a depth of 10 km. The both earthquakes were felt with a seismic intensity of 7 in Japan Metrological Agency (JMA) scale at Mashiki Town. The intensity of 7 is the highest level by definition. Very strong accelerations are observed by the M6.5 event with 1,580 gal at KiK-net Mashiki station and 1,791 gal by the M7.3 event at Ohtsu City station. As a result, more than 8,000 houses are totally collapsed, 26,000 are heavily collapsed, and 120,000 are partially damaged. There are 49 people directly killed and 32 are indirectly killed by the quakes. The most important lesson from the Kumamoto earthquake is that a very strong ground motion may hit immediately after the first large event, say in a few days. This has serious impact to a house damaged by the first large quake. In the 2016 Kumamoto sequence there are also many strong aftershocks including 4 M5.8-5.9 events till April 18th. More than 180,000 people, at most, took shelter because of scaring many strong aftershocks. I will discuss both natural and human aspects of the Kumamoto earthquake disaster by the in-land shallow large earthquakes suggesting lessons for the large Metropolitan Earthquakes in Tokyo, Japan.

Pattern of ground deformation in Kathmandu valley during 2015 Gorkha Earthquake, central Nepal

NASA Astrophysics Data System (ADS)

Ghimire, S.; Dwivedi, S. K.; Acharya, K. K.

2016-12-01

The 25th April 2015 Gorkha Earthquake (Mw=7.8) epicentered at Barpak along with thousands of aftershocks released seismic moment nearly equivalent to an 8.0 Magnitude earthquake rupturing a 150km long fault segment. Although Kathmandu valley was supposed to be severely devastated by such major earthquake, post earthquake scenario is completely different. The observed destruction is far less than anticipated as well as the spatial pattern is different than expected. This work focuses on the behavior of Kathmandu valley sediments during the strong shaking by the 2015 Gorkha Earthquake. For this purpose spatial pattern of destruction is analyzed at heavily destructed sites. To understand characteristics of subsurface soil 2D-MASW survey was carried out using a 24-channel seismograph system. An accellerogram recorded by Nepal Seismological Center was analyzed to characterize the strong ground motion. The Kathmandu valley comprises fluvio-lacustrine deposit with gravel, sand, silt and clay along with few exposures of basement rocks within the sediments. The observations show systematic repetition of destruction at an average interval of 2.5km mostly in sand, silt and clay dominated formations. Results of 2D-MASW show the sites of destruction are characterized by static deformation of soil (liquefaction and southerly dipping cracks). Spectral analysis of the accelerogram indicates maximum power associated with frequency of 1.0Hz. The result of this study explains the observed spatial pattern of destruction in Kathmandu valley. This is correlated with the seismic energy associated with the frequency of 1Hz, which generates an average wavelength of 2.5km with an average S-wave velocity of 2.5km/s. The cumulative effect of dominant frequency and associated wavelength resulted in static deformation of surface soil layers at an average interval of 2.5km. This phenomenon clearly describes the reason for different scenario than that was anticipated in Kathmandu valley.

Accuracy of three-dimensional seismic ground response analysis in time domain using nonlinear numerical simulations

NASA Astrophysics Data System (ADS)

Liang, Fayun; Chen, Haibing; Huang, Maosong

2017-07-01

To provide appropriate uses of nonlinear ground response analysis for engineering practice, a three-dimensional soil column with a distributed mass system and a time domain numerical analysis were implemented on the OpenSees simulation platform. The standard mesh of a three-dimensional soil column was suggested to be satisfied with the specified maximum frequency. The layered soil column was divided into multiple sub-soils with a different viscous damping matrix according to the shear velocities as the soil properties were significantly different. It was necessary to use a combination of other one-dimensional or three-dimensional nonlinear seismic ground analysis programs to confirm the applicability of nonlinear seismic ground motion response analysis procedures in soft soil or for strong earthquakes. The accuracy of the three-dimensional soil column finite element method was verified by dynamic centrifuge model testing under different peak accelerations of the earthquake. As a result, nonlinear seismic ground motion response analysis procedures were improved in this study. The accuracy and efficiency of the three-dimensional seismic ground response analysis can be adapted to the requirements of engineering practice.

Chapter D. The Loma Prieta, California, Earthquake of October 17, 1989 - Earth Structures and Engineering Characterization of Ground Motion

USGS Publications Warehouse

Holzer, Thomas L.

1998-01-01

This chapter contains two papers that summarize the performance of engineered earth structures, dams and stabilized excavations in soil, and two papers that characterize for engineering purposes the attenuation of ground motion with distance during the Loma Prieta earthquake. Documenting the field performance of engineered structures and confirming empirically based predictions of ground motion are critical for safe and cost effective seismic design of future structures as well as the retrofitting of existing ones.

Accelerated plate tectonics.

PubMed

Anderson, D L

1975-03-21

The concept of a stressed elastic lithospheric plate riding on a viscous asthenosphere is used to calculate the recurrence interval of great earthquakes at convergent plate boundaries, the separation of decoupling and lithospheric earthquakes, and the migration pattern of large earthquakes along an arc. It is proposed that plate motions accelerate after great decoupling earthquakes and that most of the observed plate motions occur during short periods of time, separated by periods of relative quiescence.

Estimation of Static Coulomb Stress Change and Strong Motion Simulation for Jiuzhaigou 7.0 Earthquake Base on SENTINEL-1 Insar Data Inversion

NASA Astrophysics Data System (ADS)

Shen, W. H.; Luo, Y.; Jiao, Q. S.

2018-04-01

On August 8, 2017, an earthquake of M 7.0 occurred at Jiuzhaigou. Based on the Sentinel-1 satellite InSAR data, we obtained coseismic deformation field and inverted the source slip model. Results show that this event is dominated by strike slip, and the total released seismic moment is 8.06 × 1018 Nm, equivalent to an earthquake of Mw 6.57. We calculated static stress changes along strike and dip direction, and the static stress analysis show that the average stress drop are at low level, which may be responsible for the low level of ground motion during Jiuzhaigou earthquake. The coseismic Coulomb stress changes are calculated base on the inverted slip model, which revealed that 82.59 % of aftershocks are located in the Coulomb stress increasing area, 78.42 % of total aftershocks may be triggered by the mainshock aftershock, indicating that the mainshock has a significant triggering effect on the subsequent aftershocks. Based on stochastic finite fault model, we simulated regional peak ground acceleration (PGA), peak ground velocity (PGV) and the intensity, and results could capture basic features associated with the ground motion patterns. Moreover, the simulated results reflect the obvious rupture directivity effect.

A combined source and site-effect study of ground motions generated by an earthquake in Port au Prince (Haiti)

NASA Astrophysics Data System (ADS)

St Fleur, Sadrac; Courboulex, Francoise; Bertrand, Etienne; Deschamps, Anne; Mercier de Lepinay, Bernard; Prepetit, Claude; Hough, Suzan

2013-04-01

We present the preliminary results of a study with the aim of understanding how some combinations of source and site effects can generate extreme ground motions in the city of Port au Prince. For this study, we have used the recordings of several tens of earthquakes with magnitude larger than 3.0 at 3 to 14 stations from three networks: 3 stations of the Canadian Broad-band network (RNCan), 2 stations of the educational French network (SaE) and 9 stations of the accelerometric network (Bureau des Mines et de l'Energie of Port au Prince and US Geological survey). In order to estimate site effects under each station, we have applied classical spectral ratio methods: The H/V (Horizontal/Vertical) method was first used to select a reference station, which was itself used in a site/reference method. Because a true reference station was not available, we have used successively stations HCEA, then station PAPH, then an average value of 3 stations. In the frequency range studied (0.5 - 20 Hz), we found a site-to-reference ratio up to 3 to 8. However, these values present a large variability, depending on the earthquake recordings. This may indicate that the observed amplification from one station to the other depends not only from the local site effect but also from the source. We then used the same earthquake recordings as Empirical Green's Functions (EGF) in order to simulate the ground motions generated by a virtual earthquake. For this simulation, we have used a stochastic EGF summation method. We have worked on the simulation of a magnitude Mw=6.8 using successively 2 smaller events that occurred on the Leogane fault as EGF. The results obtained using the two events are surprisingly very different. Using the first EGF, we obtained almost the same ground motion values at each station in Port au Prince, whereas with the second EGF, the results highlight large differences. The large variability obtained in the results indicates that a particular combination of site and

Combining multiple earthquake models in real time for earthquake early warning

USGS Publications Warehouse

Minson, Sarah E.; Wu, Stephen; Beck, James L; Heaton, Thomas H.

2017-01-01

The ultimate goal of earthquake early warning (EEW) is to provide local shaking information to users before the strong shaking from an earthquake reaches their location. This is accomplished by operating one or more real‐time analyses that attempt to predict shaking intensity, often by estimating the earthquake’s location and magnitude and then predicting the ground motion from that point source. Other EEW algorithms use finite rupture models or may directly estimate ground motion without first solving for an earthquake source. EEW performance could be improved if the information from these diverse and independent prediction models could be combined into one unified, ground‐motion prediction. In this article, we set the forecast shaking at each location as the common ground to combine all these predictions and introduce a Bayesian approach to creating better ground‐motion predictions. We also describe how this methodology could be used to build a new generation of EEW systems that provide optimal decisions customized for each user based on the user’s individual false‐alarm tolerance and the time necessary for that user to react.

The 2015 Gorkha (Nepal) earthquake sequence: I. Source modeling and deterministic 3D ground shaking

NASA Astrophysics Data System (ADS)

Wei, Shengji; Chen, Meng; Wang, Xin; Graves, Robert; Lindsey, Eric; Wang, Teng; Karakaş, Çağıl; Helmberger, Don

2018-01-01

To better quantify the relatively long period (< 0.3 Hz) shaking experienced during the 2015 Gorkha (Nepal) earthquake sequence, we study the finite rupture processes and the associated 3D ground motion of the Mw7.8 mainshock and the Mw7.2 aftershock. The 3D synthetics are then used in the broadband ground shaking in Kathmandu with a hybrid approach, summarized in a companion paper (Chen and Wei, 2017, submitted together). We determined the coseismic rupture process of the mainshock by joint inversion of InSAR/SAR, GPS (static and high-rate), strong motion and teleseismic waveforms. Our inversion for the mainshock indicates unilateral rupture towards the ESE, with an average rupture speed of 3.0 km/s and a total duration of 60 s. Additionally, we find that the beginning part of the rupture (5-18 s) has about 40% longer rise time than the rest of the rupture, as well as slower rupture velocity. Our model shows two strong asperities occurring 24 s and 36 s after the origin and located 30 km to the northwest and northeast of the Kathmandu valley, respectively. In contrast, the Mw7.2 aftershock is more compact both in time and space, as revealed by joint inversion of teleseismic body waves and InSAR data. The different rupture features between the mainshock and the aftershock could be related to difference in fault zone structure. The mainshock and aftershock ground motions in the Kathmandu valley, recorded by both strong motion and high-rate GPS stations, exhibited strong amplification around 0.2 Hz. A simplified 3D basin model, calibrated by an Mw5.2 aftershock, can match the observed waveforms reasonably well at 0.3 Hz and lower frequency. The 3D simulations indicate that the basin structure trapped the wavefield and produced an extensive ground vibration. Our study suggests that the combination of rupture characteristics and propagational complexity are required to understand the ground shaking produced by hazardous earthquakes such as the Gorkha event.

Using SW4 for 3D Simulations of Earthquake Strong Ground Motions: Application to Near-Field Strong Motion, Building Response, Basin Edge Generated Waves and Earthquakes in the San Francisco Bay Are

NASA Astrophysics Data System (ADS)

Rodgers, A. J.; Pitarka, A.; Petersson, N. A.; Sjogreen, B.; McCallen, D.; Miah, M.

2016-12-01

Simulation of earthquake ground motions is becoming more widely used due to improvements of numerical methods, development of ever more efficient computer programs (codes), and growth in and access to High-Performance Computing (HPC). We report on how SW4 can be used for accurate and efficient simulations of earthquake strong motions. SW4 is an anelastic finite difference code based on a fourth order summation-by-parts displacement formulation. It is parallelized and can run on one or many processors. SW4 has many desirable features for seismic strong motion simulation: incorporation of surface topography; automatic mesh generation; mesh refinement; attenuation and supergrid boundary conditions. It also has several ways to introduce 3D models and sources (including Standard Rupture Format for extended sources). We are using SW4 to simulate strong ground motions for several applications. We are performing parametric studies of near-fault motions from moderate earthquakes to investigate basin edge generated waves and large earthquakes to provide motions to engineers study building response. We show that 3D propagation near basin edges can generate significant amplifications relative to 1D analysis. SW4 is also being used to model earthquakes in the San Francisco Bay Area. This includes modeling moderate (M3.5-5) events to evaluate the United States Geologic Survey's 3D model of regional structure as well as strong motions from the 2014 South Napa earthquake and possible large scenario events. Recently SW4 was built on a Commodity Technology Systems-1 (CTS-1) at LLNL, new systems for capacity computing at the DOE National Labs. We find SW4 scales well and runs faster on these systems compared to the previous generation of LINUX clusters.

Rupture process of the M 7.9 Denali fault, Alaska, earthquake: Subevents, directivity, and scaling of high-frequency ground motions

USGS Publications Warehouse

Frankel, A.

2004-01-01

Displacement waveforms and high-frequency acceleration envelopes from stations at distances of 3-300 km were inverted to determine the source process of the M 7.9 Denali fault earthquake. Fitting the initial portion of the displacement waveforms indicates that the earthquake started with an oblique thrust subevent (subevent # 1) with an east-west-striking, north-dipping nodal plane consistent with the observed surface rupture on the Susitna Glacier fault. Inversion of the remainder of the waveforms (0.02-0.5 Hz) for moment release along the Denali and Totschunda faults shows that rupture proceeded eastward on the Denali fault, with two strike-slip subevents (numbers 2 and 3) centered about 90 and 210 km east of the hypocenter. Subevent 2 was located across from the station at PS 10 (Trans-Alaska Pipeline Pump Station #10) and was very localized in space and time. Subevent 3 extended from 160 to 230 km east of the hypocenter and had the largest moment of the subevents. Based on the timing between subevent 2 and the east end of subevent 3, an average rupture velocity of 3.5 km/sec, close to the shear wave velocity at the average rupture depth, was found. However, the portion of the rupture 130-220 km east of the epicenter appears to have an effective rupture velocity of about 5.0 km/ sec, which is supershear. These two subevents correspond approximately to areas of large surface offsets observed after the earthquake. Using waveforms of the M 6.7 Nenana Mountain earthquake as empirical Green's functions, the high-frequency (1-10 Hz) envelopes of the M 7.9 earthquake were inverted to determine the location of high-frequency energy release along the faults. The initial thrust subevent produced the largest high-frequency energy release per unit fault length. The high-frequency envelopes and acceleration spectra (>0.5 Hz) of the M 7.9 earthquake can be simulated by chaining together rupture zones of the M 6.7 earthquake over distances from 30 to 180 km east of the

Fault- and Area-Based PSHA in Nepal using OpenQuake: New Insights from the 2015 M7.8 Gorkha-Nepal Earthquake

NASA Astrophysics Data System (ADS)

Stevens, Victoria

2017-04-01

The 2015 Gorkha-Nepal M7.8 earthquake (hereafter known simply as the Gorkha earthquake) highlights the seismic risk in Nepal, allows better characterization of the geometry of the Main Himalayan Thrust (MHT), and enables comparison of recorded ground-motions with predicted ground-motions. These new data, together with recent paleoseismic studies and geodetic-based coupling models, allow for good parameterization of the fault characteristics. Other faults in Nepal remain less well studied. Unlike previous PSHA studies in Nepal that are exclusively area-based, we use a mix of faults and areas to describe six seismic sources in Nepal. For each source, the Gutenberg-Richter a and b values are found, and the maximum magnitude earthquake estimated, using a combination of earthquake catalogs, moment conservation principals and similarities to other tectonic regions. The MHT and Karakoram fault are described as fault sources, whereas four other sources - normal faulting in N-S trending grabens of northern Nepal, strike-slip faulting in both eastern and western Nepal, and background seismicity - are described as area sources. We use OpenQuake (http://openquake.org/) to carry out the analysis, and peak ground acceleration (PGA) at 2 and 10% chance in 50 years is found for Nepal, along with hazard curves at various locations. We compare this PSHA model with previous area-based models of Nepal. The Main Himalayan Thrust is the principal seismic hazard in Nepal so we study the effects of changing several parameters associated with this fault. We compare ground shaking predicted from various fault geometries suggested from the Gorkha earthquake with each other, and with a simple model of a flat fault. We also show the results from incorporating a coupling model based on geodetic data and microseismicity, which limits the down-dip extent of rupture. There have been no ground-motion prediction equations (GMPEs) developed specifically for Nepal, so we compare the results of

Introduction to the special issue on the 2004 Parkfield earthquake and the Parkfield earthquake prediction experiment

USGS Publications Warehouse

Harris, R.A.; Arrowsmith, J.R.

2006-01-01

The 28 September 2004 M 6.0 Parkfield earthquake, a long-anticipated event on the San Andreas fault, is the world's best recorded earthquake to date, with state-of-the-art data obtained from geologic, geodetic, seismic, magnetic, and electrical field networks. This has allowed the preearthquake and postearthquake states of the San Andreas fault in this region to be analyzed in detail. Analyses of these data provide views into the San Andreas fault that show a complex geologic history, fault geometry, rheology, and response of the nearby region to the earthquake-induced ground movement. Although aspects of San Andreas fault zone behavior in the Parkfield region can be modeled simply over geological time frames, the Parkfield Earthquake Prediction Experiment and the 2004 Parkfield earthquake indicate that predicting the fine details of future earthquakes is still a challenge. Instead of a deterministic approach, forecasting future damaging behavior, such as that caused by strong ground motions, will likely continue to require probabilistic methods. However, the Parkfield Earthquake Prediction Experiment and the 2004 Parkfield earthquake have provided ample data to understand most of what did occur in 2004, culminating in significant scientific advances.

SENSITIVITY OF STRUCTURAL RESPONSE TO GROUND MOTION SOURCE AND SITE PARAMETERS.

USGS Publications Warehouse

Safak, Erdal; Brebbia, C.A.; Cakmak, A.S.; Abdel Ghaffar, A.M.

1985-01-01

Designing structures to withstand earthquakes requires an accurate estimation of the expected ground motion. While engineers use the peak ground acceleration (PGA) to model the strong ground motion, seismologists use physical characteristics of the source and the rupture mechanism, such as fault length, stress drop, shear wave velocity, seismic moment, distance, and attenuation. This study presents a method for calculating response spectra from seismological models using random vibration theory. It then investigates the effect of various source and site parameters on peak response. Calculations are based on a nonstationary stochastic ground motion model, which can incorporate all the parameters both in frequency and time domains. The estimation of the peak response accounts for the effects of the non-stationarity, bandwidth and peak correlations of the response.

Earthquakes on Your Dinner Table

NASA Astrophysics Data System (ADS)

Alexeev, N. A.; Tape, C.; Alexeev, V. A.

2016-12-01

Earthquakes have interesting physics applicable to other phenomena like propagation of waves, also, they affect human lives. This study focused on three questions, how: depth, distance from epicenter and ground hardness affect earthquake strength. Experimental setup consisted of a gelatin slab to simulate crust. The slab was hit with a weight and earthquake amplitude was measured. It was found that earthquake amplitude was larger when the epicenter was deeper, which contradicts observations and probably was an artifact of the design. Earthquake strength was inversely proportional to the distance from the epicenter, which generally follows reality. Soft and medium jello were implanted into hard jello. It was found that earthquakes are stronger in softer jello, which was a result of resonant amplification in soft ground. Similar results are found in Minto Flats, where earthquakes are stronger and last longer than in the nearby hills. Earthquakes waveforms from Minto Flats showed that that the oscillations there have longer periods compared to the nearby hills with harder soil. Two gelatin pieces with identical shapes and different hardness were vibrated on a platform at varying frequencies in order to demonstrate that their resonant frequencies are statistically different. This phenomenon also occurs in Yukon Flats.

A New Simplified Source Model to Explain Strong Ground Motions from a Mega-Thrust Earthquake - Application to the 2011 Tohoku Earthquake (Mw9.0) -

NASA Astrophysics Data System (ADS)

Nozu, A.

2013-12-01

A new simplified source model is proposed to explain strong ground motions from a mega-thrust earthquake. The proposed model is simpler, and involves less model parameters, than the conventional characterized source model, which itself is a simplified expression of actual earthquake source. In the proposed model, the spacio-temporal distribution of slip within a subevent is not modeled. Instead, the source spectrum associated with the rupture of a subevent is modeled and it is assumed to follow the omega-square model. By multiplying the source spectrum with the path effect and the site amplification factor, the Fourier amplitude at a target site can be obtained. Then, combining it with Fourier phase characteristics of a smaller event, the time history of strong ground motions from the subevent can be calculated. Finally, by summing up contributions from the subevents, strong ground motions from the entire rupture can be obtained. The source model consists of six parameters for each subevent, namely, longitude, latitude, depth, rupture time, seismic moment and corner frequency of the subevent. Finite size of the subevent can be taken into account in the model, because the corner frequency of the subevent is included in the model, which is inversely proportional to the length of the subevent. Thus, the proposed model is referred to as the 'pseudo point-source model'. To examine the applicability of the model, a pseudo point-source model was developed for the 2011 Tohoku earthquake. The model comprises nine subevents, located off Miyagi Prefecture through Ibaraki Prefecture. The velocity waveforms (0.2-1 Hz), the velocity envelopes (0.2-10 Hz) and the Fourier spectra (0.2-10 Hz) at 15 sites calculated with the pseudo point-source model agree well with the observed ones, indicating the applicability of the model. Then the results were compared with the results of a super-asperity (SPGA) model of the same earthquake (Nozu, 2012, AGU), which can be considered as an

Seismoelectric ground response to local and regional earthquakes

NASA Astrophysics Data System (ADS)

Dzieran, Laura; Rabbel, Wolfgang; Thorwart, Martin; Ritter, Oliver

2017-04-01

During earthquakes magnetotelluric stations occasionally record electric and magnetic signals similar to seismograms. The major part of these magnetic signals is induced by the seismic movement of the magnetometers (induction coils) in the static magnetic field. In contrast, the electric field signals are caused by the seismoelectric effect. Based on more than 600 earthquakes from Chile, Costa Rica and Europe we established a logarithmic magnitude-distance-relationship describing the magnitude threshold to be exceeded for observing seismoelectric (SE) signals with standard magnetotelluric (MT) recording units at given hypocentral distance r and for noise levels less than 3 μV/m. The log(r) term results from the geometric spreading of the radiated seismic waves. A comparison of SE signals at different hypocentral distances shows that observability is not only influenced by the amplitude of the incoming seismic wave. It also depends on the geological structure underneath the station which causes a unique frequency dependent SE response. To quantify these site effects we computed spectral seismoelectric transfer functions representing the ratios of the spectral amplitudes of SE records and acceleration seismograms (SESRs). Some stations show constant SESRs in the major frequency range, while others show a decrease with increasing frequencies. Based on the current Biot-type seismoelectric theory constant SESRs can be explained by coseismic SE waves alone. The observed SESR amplitudes at some sites are indeed consistent with theoretical expectations for electrically highly resistive soils or rocks, in agreement with the local geology of the investigated areas. The frequency dependence of SESRs observed at other locations can be explained if the incident SE waves consist not only of coseismic arrivals but also of a significant contribution from SE interface response waves which are generated at electrical or mechanical boundaries. Therefore, frequency-dependent SESRs

Establishment of Antakya Basin Strong Ground Motion Monitoring System

NASA Astrophysics Data System (ADS)

Durukal, E.; Özel, O.; Bikce, M.; Geneş, M. C.; Kacın, S.; Erdik, M.; Safak, E.; Över, S.

2009-04-01

Turkey is located in one of the most active earthquake zones of the world. The cities located along the North Anatolian Fault (NAF) and the East Anatolian Fault (EAF) are exposed to significant earthquake hazard. The Hatay province near the southern terminus of the EAF has always experienced a significant seismic activity, since it is on the intersection of the northernmost segment of Dead Sea Fault Zone coming from the south, with the Cyprean Arc approaching from south-west. Historical records extending over the last 2000 years indicate that Antakya, founded in the 3rd century B.C., is effected by intensity IX-X earthquakes every 150 years. In the region, the last destructive earthquake occurred in 1872. Destructive earthquakes should be expected in the region in the near future similar to the ones that occurred in the past. The strong response of sedimentary basins to seismic waves was largely responsible for the damage produced by the devastating earthquakes of 1985 Michoacan Earthquake which severely damaged parts of Mexico City, and the 1988 Spitak Earthquake which destroyed most of Leninakan, Armenia. Much of this devastating response was explained by the conversion of seismic body waves to surface waves at the sediment/rock contacts of sedimentary basins. "Antakya Basin Strong Ground Motion Monitoring System" is set up with the aim of monitoring the earthquake response of the Antakya Basin, contributing to our understanding of basin response, contributing to earthquake risk assessment of Antakya, monitoring of regional earthquakes and determining the effects of local and regional earthquakes on the urban environment of Antakya. The soil properties beneath the strong motion stations (S-Wave velocity structure and dominant soil frequency) are determined by array measurements that involve broad-band seismometers. The strong motion monitoring system consists of six instruments installed in small buildings. The stations form a straight line along the short axis

Seismicity in the block mountains between Halle and Leipzig, Central Germany: centroid moment tensors, ground motion simulation, and felt intensities of two M ≈ 3 earthquakes in 2015 and 2017

NASA Astrophysics Data System (ADS)

Dahm, Torsten; Heimann, Sebastian; Funke, Sigward; Wendt, Siegfried; Rappsilber, Ivo; Bindi, Dino; Plenefisch, Thomas; Cotton, Fabrice

2018-05-01

On April 29, 2017 at 0:56 UTC (2:56 local time), an M W = 2.8 earthquake struck the metropolitan area between Leipzig and Halle, Germany, near the small town of Markranstädt. The earthquake was felt within 50 km from the epicenter and reached a local intensity of I 0 = IV. Already in 2015 and only 15 km northwest of the epicenter, a M W = 3.2 earthquake struck the area with a similar large felt radius and I 0 = IV. More than 1.1 million people live in the region, and the unusual occurrence of the two earthquakes led to public attention, because the tectonic activity is unclear and induced earthquakes have occurred in neighboring regions. Historical earthquakes south of Leipzig had estimated magnitudes up to M W ≈ 5 and coincide with NW-SE striking crustal basement faults. We use different seismological methods to analyze the two recent earthquakes and discuss them in the context of the known tectonic structures and historical seismicity. Novel stochastic full waveform simulation and inversion approaches are adapted for the application to weak, local earthquakes, to analyze mechanisms and ground motions and their relation to observed intensities. We find NW-SE striking normal faulting mechanisms for both earthquakes and centroid depths of 26 and 29 km. The earthquakes are located where faults with large vertical offsets of several hundred meters and Hercynian strike have developed since the Mesozoic. We use a stochastic full waveform simulation to explain the local peak ground velocities and calibrate the method to simulate intensities. Since the area is densely populated and has sensitive infrastructure, we simulate scenarios assuming that a 12-km long fault segment between the two recent earthquakes is ruptured and study the impact of rupture parameters on ground motions and expected damage.

Source characterization of moderate induced earthquakes in Oklahoma, USA: A case study of 2013-2016 Cushing earthquake sequence