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Sample records for active faults including

  1. Central Asia Active Fault Database

    NASA Astrophysics Data System (ADS)

    Mohadjer, Solmaz; Ehlers, Todd A.; Kakar, Najibullah

    2014-05-01

    The ongoing collision of the Indian subcontinent with Asia controls active tectonics and seismicity in Central Asia. This motion is accommodated by faults that have historically caused devastating earthquakes and continue to pose serious threats to the population at risk. Despite international and regional efforts to assess seismic hazards in Central Asia, little attention has been given to development of a comprehensive database for active faults in the region. To address this issue and to better understand the distribution and level of seismic hazard in Central Asia, we are developing a publically available database for active faults of Central Asia (including but not limited to Afghanistan, Tajikistan, Kyrgyzstan, northern Pakistan and western China) using ArcGIS. The database is designed to allow users to store, map and query important fault parameters such as fault location, displacement history, rate of movement, and other data relevant to seismic hazard studies including fault trench locations, geochronology constraints, and seismic studies. Data sources integrated into the database include previously published maps and scientific investigations as well as strain rate measurements and historic and recent seismicity. In addition, high resolution Quickbird, Spot, and Aster imagery are used for selected features to locate and measure offset of landforms associated with Quaternary faulting. These features are individually digitized and linked to attribute tables that provide a description for each feature. Preliminary observations include inconsistent and sometimes inaccurate information for faults documented in different studies. For example, the Darvaz-Karakul fault which roughly defines the western margin of the Pamir, has been mapped with differences in location of up to 12 kilometers. The sense of motion for this fault ranges from unknown to thrust and strike-slip in three different studies despite documented left-lateral displacements of Holocene and late

  2. Active, capable, and potentially active faults - a paleoseismic perspective

    USGS Publications Warehouse

    Machette, M.N.

    2000-01-01

    Maps of faults (geologically defined source zones) may portray seismic hazards in a wide range of completeness depending on which types of faults are shown. Three fault terms - active, capable, and potential - are used in a variety of ways for different reasons or applications. Nevertheless, to be useful for seismic-hazards analysis, fault maps should encompass a time interval that includes several earthquake cycles. For example, if the common recurrence in an area is 20,000-50,000 years, then maps should include faults that are 50,000-100,000 years old (two to five typical earthquake cycles), thus allowing for temporal variability in slip rate and recurrence intervals. Conversely, in more active areas such as plate boundaries, maps showing faults that are <10,000 years old should include those with at least 2 to as many as 20 paleoearthquakes. For the International Lithosphere Programs' Task Group II-2 Project on Major Active Faults of the World our maps and database will show five age categories and four slip rate categories that allow one to select differing time spans and activity rates for seismic-hazard analysis depending on tectonic regime. The maps are accompanied by a database that describes evidence for Quaternary faulting, geomorphic expression, and paleoseismic parameters (slip rate, recurrence interval and time of most recent surface faulting). These maps and databases provide an inventory of faults that would be defined as active, capable, and potentially active for seismic-hazard assessments.

  3. Naval Weapons Center Active Fault Map Series.

    DTIC Science & Technology

    1987-08-31

    SECURITY CLASSIFICATION OF ’MiS PACE NWC TP 6828 CONTENTS Introduction . . . . . . . . . . . . . . . . . ........... 2 Active Fault Definition ...established along the trace of the Little Take fault zone, within the City of Ridgecrest. ACTIVE FAULT DEFINITION Although it is a commonly used term...34active fault" lacks a pre- cise and universally accepted definition . Most workers, however, accept the following: "Active fault - a fault along

  4. Active faulting in the Walker Lane

    NASA Astrophysics Data System (ADS)

    Wesnousky, Steven G.

    2005-06-01

    Deformation across the San Andreas and Walker Lane fault systems accounts for most relative Pacific-North American transform plate motion. The Walker Lane is composed of discontinuous sets of right-slip faults that are located to the east and strike approximately parallel to the San Andreas fault system. Mapping of active faults in the central Walker Lane shows that right-lateral shear is locally accommodated by rotation of crustal blocks bounded by steep-dipping east striking left-slip faults. The left slip and clockwise rotation of crustal blocks bounded by the east striking faults has produced major basins in the area, including Rattlesnake and Garfield flats; Teels, Columbus and Rhodes salt marshes; and Queen Valley. The Benton Springs and Petrified Springs faults are the major northwest striking structures currently accommodating transform motion in the central Walker Lane. Right-lateral offsets of late Pleistocene surfaces along the two faults point to slip rates of at least 1 mm/yr. The northern limit of northwest trending strike-slip faults in the central Walker Lane is abrupt and reflects transfer of strike-slip to dip-slip deformation in the western Basin and Range and transformation of right slip into rotation of crustal blocks to the north. The transfer of strike slip in the central Walker Lane to dip slip in the western Basin and Range correlates to a northward broadening of the modern strain field suggested by geodesy and appears to be a long-lived feature of the deformation field. The complexity of faulting and apparent rotation of crustal blocks within the Walker Lane is consistent with the concept of a partially detached and elastic-brittle crust that is being transported on a continuously deforming layer below. The regional pattern of faulting within the Walker Lane is more complex than observed along the San Andreas fault system to the west. The difference is attributed to the relatively less cumulative slip that has occurred across the Walker

  5. Deep pulverization along active faults ?

    NASA Astrophysics Data System (ADS)

    Doan, M.

    2013-12-01

    Pulverization is a intensive damage observed along some active faults. Rarely found in the field, it has been associated with dynamic damage produced by large earthquakes. Pulverization has been so far only described at the ground surface, consistent with the high frequency tensile loading expected for earthquake occurring along bimaterial faults. However, we discuss here a series of hints suggesting that pulverization is expected also several hundred of meters deep. In the deep well drilled within Nojima fault after the 1995 Kobe earthquake, thin sections reveal non localized damage, with microfractured pervading a sample, but with little shear disturbing the initial microstructure. In the SAFOD borehole drilled near Parkfield, Wiersberg and Erzinger (2008) made gas monitoring while drilling found large amount of H2 gas in the sandstone west to the fault. They attribute this high H2 concentration to mechanochemical origin, in accordance with some example of diffuse microfracturing found in thin sections from cores of SAFOD phase 3 and from geophysical data from logs. High strain rate experiments in both dry (Yuan et al, 2011) and wet samples (Forquin et al, 2010) show that even under confining pressures of several tens of megapascals, diffuse damage similar to pulverization is possible. This could explain the occurrence of pulverization at depth.

  6. Injection-induced seismicity on basement faults including poroelastic stressing

    NASA Astrophysics Data System (ADS)

    Chang, K. W.; Segall, P.

    2016-04-01

    Most significant induced earthquakes occur on faults within the basement beneath sedimentary cover. In this two-dimensional plane strain numerical study, we examine the full poroelastic response of basement faults to fluid injection into overlying strata, considering both (1) the permeability of the fault zone and (2) the hydraulic connectivity of the faults to the target horizon. Given hydraulic and mechanical properties, we compute the spatiotemporal change in Coulomb stress, which we separate into (1) the change in poroelastic stresses Δτs+fΔσn, where Δτs and Δσn are changes in shear and normal stress (Δτs>0 and Δσn>0 both favor slip), and (2) the change in pore pressure fΔp. Pore pressure diffusion into hydraulically connected, permeable faults dominates their mechanical stability. For hydraulically isolated or low-permeability faults, however, poroelastic stresses transmitted to deeper basement levels can trigger slip, even without elevated pore pressure. The seismicity rate on basement fault zones is predicted using the model of Dieterich (1994). High seismicity rates can occur on permeable, hydraulically connected faults due to direct pore pressure diffusion. Lower rates are predicted on isolated steeply dipping normal faults, caused solely by poroelastic stressing. In contrast, seismicity on similarly oriented reverse faults is inhibited.

  7. Fault zone structure and inferences on past activities of the active Shanchiao Fault in the Taipei metropolis, northern Taiwan

    NASA Astrophysics Data System (ADS)

    Chen, C.; Lee, J.; Chan, Y.; Lu, C.

    2010-12-01

    The Taipei Metropolis, home to around 10 million people, is subject to seismic hazard originated from not only distant faults or sources scattered throughout the Taiwan region, but also active fault lain directly underneath. Northern Taiwan including the Taipei region is currently affected by post-orogenic (Penglai arc-continent collision) processes related to backarc extension of the Ryukyu subduction system. The Shanchiao Fault, an active normal fault outcropping along the western boundary of the Taipei Basin and dipping to the east, is investigated here for its subsurface structure and activities. Boreholes records in the central portion of the fault were analyzed to document the stacking of post- Last Glacial Maximum growth sediments, and a tulip flower structure is illuminated with averaged vertical slip rate of about 3 mm/yr. Similar fault zone architecture and post-LGM tectonic subsidence rate is also found in the northern portion of the fault. A correlation between geomorphology and structural geology in the Shanchiao Fault zone demonstrates an array of subtle geomorphic scarps corresponds to the branch fault while the surface trace of the main fault seems to be completely erased by erosion and sedimentation. Such constraints and knowledge are crucial in earthquake hazard evaluation and mitigation in the Taipei Metropolis, and in understanding the kinematics of transtensional tectonics in northern Taiwan. Schematic 3D diagram of the fault zone in the central portion of the Shanchiao Fault, displaying regional subsurface geology and its relation to topographic features.

  8. Naval weapons center active fault map series

    NASA Astrophysics Data System (ADS)

    Roquemore, G. R.; Zellmer, J. T.

    1987-08-01

    The NWC Active Fault Map Series shows the locations of active faults and features indicative of active faulting within much of Indian Wells Valley and portions of the Randsburg Wash/Mojave B test range areas of the Naval Weapons Center. Map annotations are used extensively to identify criteria employed in identifying the fault offsets, and to present other valuable data. All of the mapped faults show evidence of having moved during about the last 12,500 years or represent geologically young faults that occur within seismic gaps. Only faults that offset the surface or show other evidence of surface deformation were mapped. A portion of the City of Ridgecrest is recommended as being a Seismic Hazard Special Studies Zone in which detailed earthquake hazard studies should be required.

  9. Fault displacement rates and recent activity on the Ierapetra Fault Zone, Crete, Greece

    NASA Astrophysics Data System (ADS)

    Veliz, V.

    2015-12-01

    Crete is an eastern Mediterranean island that includes the highest forearc topography of the Hellenic subduction margin, along which the African and Eurasian plates converge at rates of ~40 mm/yr. The island is currently experiencing regional uplift and is broken up by numerous active normal faults that contribute to the shaping of its topography. The largest of these onshore tectonic features is, the Ierapetra Fault Zone (IFZ), a normal fault that traverses the entire width of eastern Crete (>20 km) with a NNE strike and west diping. Here we use geomorphologic, structural and kinematic indicators to discuss fault segmentation along the IFZ and to provide quantitative constraints on the late Quaternary (~16.5 and 33 kyr) displacement rate on the fault, including evidence of Holocene earthquake activity on its central segment.

  10. A review of recently active faults in Taiwan

    USGS Publications Warehouse

    Bonilla, Manuel G.

    1975-01-01

    Six faults associated with five large earthquakes produced surface displacements ranging from 1 to 3 m in the period 1906 through 1951. Four of the ruptures occurred in the western coastal plain and foothills, and two occurred in the Longitudinal Valley of eastern Taiwan. Maps are included showing the locations and dimensions of the displacements. The published geological literature probably would not lead one to infer the existence of a fault along most of the 1906 rupture, except for descriptions of the rupture itself. Over most of its length the 1935 rupture on the Chihhu fault is parallel to but more than 0.5 km from nearby faults shown on geologic maps published in 1969 and 1971; only about 1.5 km of its 15 km length coincides with a mapped fault. The coastal plain part of the Tuntzuchio fault which ruptured in 1935 is apparently not revealed by landforms, and only suggested by other data. Part of the 1946 Hsinhua faulting coincides with a fault identified in the subsurface by seismic work but surface indications of the fault are obscure. The 1951 Meilun faulting occurred along a conspicuous pre-1951 scarp and the 1951 Yuli faulting occurred near or in line with pre-1951 scarps. More than 40 faults which, according to the published literature, have had Pleistocene or later movement are shown on a small-scale map. Most of these faults are in the densely-populated western part of Taiwan. The map and text calls attention to faults that may be active and therefore may be significant in planning important structures. Equivocal evidence suggestive of fault creep was found on the Yuli fault and the Hsinhua fault. Fault creep was not found at several places examined along the 1906 fault trace. Tectonic uplift has occurred in Taiwan in the last 10,000 years and application of eustatic sea level curves to published radiocarbon dates shows that the minimum rate of uplift is considerably different in different parts of the island. Incomplete data indicate that the rate is

  11. Illuminating Northern California's Active Faults

    NASA Astrophysics Data System (ADS)

    Prentice, Carol S.; Crosby, Christopher J.; Whitehill, Caroline S.; Arrowsmith, J. Ramón; Furlong, Kevin P.; Phillips, David A.

    2009-02-01

    Newly acquired light detection and ranging (lidar) topographic data provide a powerful community resource for the study of landforms associated with the plate boundary faults of northern California (Figure 1). In the spring of 2007, GeoEarthScope, a component of the EarthScope Facility construction project funded by the U.S. National Science Foundation, acquired approximately 2000 square kilometers of airborne lidar topographic data along major active fault zones of northern California. These data are now freely available in point cloud (x, y, z coordinate data for every laser return), digital elevation model (DEM), and KMZ (zipped Keyhole Markup Language, for use in Google Earth™ and other similar software) formats through the GEON OpenTopography Portal (http://www.OpenTopography.org/data). Importantly, vegetation can be digitally removed from lidar data, producing high-resolution images (0.5- or 1.0-meter DEMs) of the ground surface beneath forested regions that reveal landforms typically obscured by vegetation canopy (Figure 2).

  12. Approximate active fault detection and control

    NASA Astrophysics Data System (ADS)

    Škach, Jan; Punčochář, Ivo; Šimandl, Miroslav

    2014-12-01

    This paper deals with approximate active fault detection and control for nonlinear discrete-time stochastic systems over an infinite time horizon. Multiple model framework is used to represent fault-free and finitely many faulty models. An imperfect state information problem is reformulated using a hyper-state and dynamic programming is applied to solve the problem numerically. The proposed active fault detector and controller is illustrated in a numerical example of an air handling unit.

  13. Active faults in southeastern Harris County, Texas

    NASA Technical Reports Server (NTRS)

    Clanton, U. S.; Amsbury, D. L.

    1975-01-01

    Aerial color infrared photography was used to investigate active faults in a complex graben in southeastern Harris County, Tex. The graben extends east-west across an oil field and an interstate highway through Ellington Air Force Base (EAFB), into the Clear Lake oil field and on to LaPorte, Tex. It was shown that the fault pattern at EAFB indicates an appreciable horizontal component associated with the failure of buildings, streets, and runways. Another fault system appears to control the shoreline configuration of Clear Lake, with some of the faults associated with tectonic movements and the production of oil and gas, but many related to extensive ground water withdrawal.

  14. Assessing active faulting by hydrogeological modeling and superconducting gravimetry: A case study for Hsinchu Fault, Taiwan

    NASA Astrophysics Data System (ADS)

    Lien, Tzuyi; Cheng, Ching-Chung; Hwang, Cheinway; Crossley, David

    2014-09-01

    We develop a new hydrology and gravimetry-based method to assess whether or not a local fault may be active. We take advantage of an existing superconducting gravimeter (SG) station and a comprehensive groundwater network in Hsinchu to apply the method to the Hsinchu Fault (HF) across the Hsinchu Science Park, whose industrial output accounts for 10% of Taiwan's gross domestic product. The HF is suspected to pose seismic hazards to the park, but its existence and structure are not clear. The a priori geometry of the HF is translated into boundary conditions imposed in the hydrodynamic model. By varying the fault's location, depth, and including a secondary wrench fault, we construct five hydrodynamic models to estimate groundwater variations, which are evaluated by comparing groundwater levels and SG observations. The results reveal that the HF contains a low hydraulic conductivity core and significantly impacts groundwater flows in the aquifers. Imposing the fault boundary conditions leads to about 63-77% reduction in the differences between modeled and observed values (both water level and gravity). The test with fault depth shows that the HF's most recent slip occurred in the beginning of Holocene, supplying a necessary (but not sufficient) condition that the HF is currently active. A portable SG can act as a virtual borehole well for model assessment at critical locations of a suspected active fault.

  15. Active Fault Topography and Fault Outcrops in the Central Part of the Nukumi fault, the 1891 Nobi Earthquake Fault System, Central Japan

    NASA Astrophysics Data System (ADS)

    Sasaki, T.; Ueta, K.; Inoue, D.; Aoyagi, Y.; Yanagida, M.; Ichikawa, K.; Goto, N.

    2010-12-01

    outcrops in this area where the surface ruptures of the 1891 Nobi earthquake have not been known. These outcrops have active fault which cut the layer of terrace deposit and slope deposit to the bottom of present soil layer in common. At the locality of Ogotani outcrop, the humic layer which age is from14th century to 15th century by 14C age dating is deformed by the active fault. The vertical displacement of the humic layer is 0.8-0.9m and the terrace deposit layer below the humic layer is ca. 1.3m. For this reason and the existence of fain grain deposit including AT tephra (28ka) in the footwall of the fault, this fault movement occurred more than once since the last glacial age. We conclude that the surface rupture of Nukumi fault in the 1891 Nobi earthquake is continuous to 9km southeast of Nukumi pass. In other words, these findings indicate that there is 10km parallel overlap zone between the surface rupture of the southeastern end of Nukumi fault and the northwestern end of Neodani fault.

  16. Project DAFNE - Drilling Active Faults in Northern Europe

    NASA Astrophysics Data System (ADS)

    Kukkonen, I. T.; Ask, M. S. V.; Olesen, O.

    2012-04-01

    We are currently developing a new ICDP project 'Drillling Active Faults in Northern Europe' (DAFNE) which aims at investigating, via scientific drilling, the tectonic and structural characteristics of postglacial (PG) faults in northern Fennoscandia, including their hydrogeology and associated deep biosphere [1, 2]. During the last stages of the Weichselian glaciation (ca. 9,000 - 15,000 years B.P.), reduced ice load and glacially affected stress field resulted in active faulting in Fennoscandia with fault scarps up to 160 km long and 30 m high. These postglacial (PG) faults are usually SE dipping, SW-NE oriented thrusts, and represent reactivated, pre-existing crustal discontinuities. Postglacial faulting indicates that the glacio-isostatic compensation is not only a gradual viscoelastic phenomenon, but includes also unexpected violent earthquakes, suggestively larger than other known earthquakes in stable continental regions. The research is anticipated to advance science in neotectonics, hydrogeology and deep biosphere studies, and provide important information for nuclear waste and CO2 disposal, petroleum exploration on the Norwegian continental shelf and studies of mineral resources in PG fault areas. We expect that multidisciplinary research applying shallow and deep drilling of postglacial faults would provide significant scientific results through generating new data and models, namely: (1) Understanding PG fault genesis and controls of their locations; (2) Deep structure and depth extent of PG faults; (3) Textural, mineralogical and physical alteration of rocks in the PG faults; (4) State of stress and estimates of paleostress of PG faults; (5) Hydrogeology, hydrochemistry and hydraulic properties of PG faults; (6) Dating of tectonic reactivation(s) and temporal evolution of tectonic systems hosting PG faults; (7) Existence/non-existence of deep biosphere in PG faults; (8) Data useful for planning radioactive waste disposal in crystalline bedrock; (9) Data

  17. Research of Earthquake Potential from Active Fault Observation in Taiwan

    NASA Astrophysics Data System (ADS)

    Chien-Liang, C.; Hu, J. C.; Liu, C. C.; En, C. K.; Cheng, T. C. T.

    2015-12-01

    We utilize GAMIT/GLOBK software to estimate the precise coordinates for continuous GPS (CGPS) data of Central Geological Survey (CGS, MOEA) in Taiwan. To promote the software estimation efficiency, 250 stations are divided by 8 subnets which have been considered by station numbers, network geometry and fault distributions. Each of subnets include around 50 CGPS and 10 international GNSS service (IGS) stations. After long period of data collection and estimation, a time series variation can be build up to study the effect of earthquakes and estimate the velocity of stations. After comparing the coordinates from campaign-mode GPS sites and precise leveling benchmarks with the time series from continuous GPS stations, the velocity field is consistent with previous measurement which show the reliability of observation. We evaluate the slip rate and slip deficit rate of active faults in Taiwan by 3D block model DEFNODE. First, to get the surface fault traces and the subsurface fault geometry parameters, and then establish the block boundary model of study area. By employing the DEFNODE technique, we invert the GPS velocities for the best-fit block rotate rates, long term slip rates and slip deficit rates. Finally, the probability analysis of active faults is to establish the flow chart of 33 active faults in Taiwan. In the past two years, 16 active faults in central and northern Taiwan have been assessed to get the recurrence interval and the probabilities for the characteristic earthquake occurred in 30, 50 and 100 years.

  18. Current status of understanding quasi-permanent fields associated with earthquakes. [including geological faults and tectonics

    NASA Technical Reports Server (NTRS)

    Brune, J. N.

    1975-01-01

    The basic concepts relating to displacement fields associated with earthquakes are described. Factors discussed include: understanding the geologic and tectonic setting, the discovery of fault creep, and an extended range of possible models of strain buildup. Problems in tectonic modeling reviewed relate to understanding (1) frictional heat generation on faults, (2) the character of stress and strain on faults below the depth of earthquakes, and (3) the predictability of major earthquakes.

  19. InSAR measurements around active faults: creeping Philippine Fault and un-creeping Alpine Fault

    NASA Astrophysics Data System (ADS)

    Fukushima, Y.

    2013-12-01

    Recently, interferometric synthetic aperture radar (InSAR) time-series analyses have been frequently applied to measure the time-series of small and quasi-steady displacements in wide areas. Large efforts in the methodological developments have been made to pursue higher temporal and spatial resolutions by using frequently acquired SAR images and detecting more pixels that exhibit phase stability. While such a high resolution is indispensable for tracking displacements of man-made and other small-scale structures, it is not necessarily needed and can be unnecessarily computer-intensive for measuring the crustal deformation associated with active faults and volcanic activities. I apply a simple and efficient method to measure the deformation around the Alpine Fault in the South Island of New Zealand, and the Philippine Fault in the Leyte Island. I use a small-baseline subset (SBAS) analysis approach (Berardino, et al., 2002). Generally, the more we average the pixel values, the more coherent the signals are. Considering that, for the deformation around active faults, the spatial resolution can be as coarse as a few hundred meters, we can severely 'multi-look' the interferograms. The two applied cases in this study benefited from this approach; I could obtain the mean velocity maps on practically the entire area without discarding decorrelated areas. The signals could have been only partially obtained by standard persistent scatterer or single-look small-baseline approaches that are much more computer-intensive. In order to further increase the signal detection capability, it is sometimes effective to introduce a processing algorithm adapted to the signal of interest. In an InSAR time-series processing, one usually needs to set the reference point because interferograms are all relative measurements. It is difficult, however, to fix the reference point when one aims to measure long-wavelength deformation signals that span the whole analysis area. This problem can be

  20. Deformation Monitoring of AN Active Fault

    NASA Astrophysics Data System (ADS)

    Ostapchuk, A.

    2015-12-01

    The discovery of low frequency earthquakes, slow slip events and other deformation phenomena, new for geophysics, change our understanding of how the energy accumulated in the Earth's crust do release. The new geophysical data make one revise the underlying mechanism of geomechanical processes taking place in fault zones. Conditions for generating different slip modes are still unclear. The most vital question is whether a certain slip mode is intrinsic for a fault or may be controlled by external factors. This work presents the results of two and a half year deformation monitoring of a discontinuity in the zone of the Main Sayanskiy Fault. Main Sayanskiy Fault is right-lateral strike-slip fault. Observations were performed in the tunnel of Talaya seismic station (TLY), Irkutsk region, Russia. Measurements were carried out 70 m away from the entrance of the tunnel, the thickness of overlying rock was about 30 m. Inductive sensors of displacement were mounted at the both sides of a discontinuity, which recorded three components of relative fault side displacement with the accuracy of 0.2 mcm. Temperature variation inside the tunnel didn't exceed 0.5oC during the all period of observations. Important information about deformation properties of an active fault was obtained. A pronounced seasonality of deformation characteristics of discontinuity is observed in the investigated segment of rock. A great number of slow slip events with durations from several hours to several weeks were registered. Besides that alterations of fault deformation characteristics before the megathrust earthquake M9.0 Tohoku Oki 11 March 2011 and reaction to the event itself were detected. The work was supported by the Russian Science Foundation (grant no. 14-17-00719).

  1. A summary of the active fault investigation in the extension sea area of Kikugawa fault and the Nishiyama fault , N-S direction fault in south west Japan

    NASA Astrophysics Data System (ADS)

    Abe, S.

    2010-12-01

    In this study, we carried out two sets of active fault investigation by the request from Ministry of Education, Culture, Sports, Science and Technology in the sea area of the extension of Kikugawa fault and the Nishiyama fault. We want to clarify the five following matters about both active faults based on those results. (1)Fault continuity of the land and the sea. (2) The length of the active fault. (3) The division of the segment. (4) Activity characteristics. In this investigation, we carried out a digital single channel seismic reflection survey in the whole area of both active faults. In addition, a high-resolution multichannel seismic reflection survey was carried out to recognize the detailed structure of a shallow stratum. Furthermore, the sampling with the vibrocoring to get information of the sedimentation age was carried out. The reflection profile of both active faults was extremely clear. The characteristics of the lateral fault such as flower structure, the dispersion of the active fault were recognized. In addition, from analysis of the age of the stratum, it was recognized that the thickness of the sediment was extremely thin in Holocene epoch on the continental shelf in this sea area. It was confirmed that the Kikugawa fault extended to the offing than the existing results of research by a result of this investigation. In addition, the width of the active fault seems to become wide toward the offing while dispersing. At present, we think that we can divide Kikugawa fault into some segments based on the distribution form of the segment. About the Nishiyama fault, reflection profiles to show the existence of the active fault was acquired in the sea between Ooshima and Kyushu. From this result and topographical existing results of research in Ooshima, it is thought that Nishiyama fault and the Ooshima offing active fault are a series of structure. As for Ooshima offing active fault, the upheaval side changes, and a direction changes too. Therefore, we

  2. a case of casing deformation and fault slip for the active fault drilling

    NASA Astrophysics Data System (ADS)

    Ge, H.; Song, L.; Yuan, S.; Yang, W.

    2010-12-01

    Active fault is normally defined as a fault with displacement or seismic activity during the geologically recent period (in the last 10,000 years, USGS). Here, we refer the active fault to the fault that is under the post-seismic stress modification or recovery. Micro-seismic, fault slip would happen during the recovery of the active faults. It is possible that the drilling through this active fault, such as the Wenchuan Fault Scientific Drilling(WFSD), will be accompanied with some possible wellbore instability and casing deformation, which is noteworthy for the fault scientific drilling. This presentation gives a field case of the Wenchuan earthquake. The great Wenchuan earthquake happened on May 12, 2008. An oilfield is 400km apart from the epicenter and 260km from the main fault. Many wells were drilled or are under drilling. Some are drilled through the active fault and a few tectonic active phenomenons were observed. For instance, a drill pipe was cut off in the well which was just drilled through the fault. We concluded that this is due to the fault slip,if not, so thick wall pipe cannot be cut off. At the same time, a mass of well casings of the oilfield deformed during the great Wenchuan Earthquake. The analysis of the casing deformation characteristic, formation structure, seismicity, tectonic stress variation suggest that the casing deformation is closely related to the Wenchuan Earthquake. It is the tectonic stress variation that induces seismic activities, fault slip, salt/gypsum creep speedup, and deformation inconsistent between stratums. Additional earthquake dynamic loads were exerted on the casing and caused its deformation. Active fault scientific drilling has become an important tool to understand earthquake mechanism and physics. The casing deformation and wellbore instability is not only a consequence of the earthquake but also an indicator of stress modification and fault activity. It is noteworthy that tectonic stress variation and fault

  3. Geophysical characterization of buried active faults: the Concud Fault (Iberian Chain, NE Spain)

    NASA Astrophysics Data System (ADS)

    Pueyo Anchuela, Óscar; Lafuente, Paloma; Arlegui, Luis; Liesa, Carlos L.; Simón, José L.

    2016-11-01

    The Concud Fault is a 14-km-long active fault that extends close to Teruel, a city with about 35,000 inhabitants in the Iberian Range (NE Spain). It shows evidence of recurrent activity during Late Pleistocene time, posing a significant seismic hazard in an area of moderate-to-low tectonic rates. A geophysical survey was carried out along the mapped trace of the southern branch of the Concud Fault to evaluate the geophysical signature from the fault and the location of paleoseismic trenches. The survey identified a lineation of inverse magnetic dipoles at residual and vertical magnetic gradient, a local increase in apparent conductivity, and interruptions of the underground sediment structure along GPR profiles. The origin of these anomalies is due to lateral contrast between both fault blocks and the geophysical signature of Quaternary materials located above and directly south of the fault. The spatial distribution of anomalies was successfully used to locate suitable trench sites and to map non-exposed segments of the fault. The geophysical anomalies are related to the sedimentological characteristics and permeability differences of the deposits and to deformation related to fault activity. The results illustrate the usefulness of geophysics to detect and map non-exposed faults in areas of moderate-to-low tectonic activity where faults are often covered by recent pediments that obscure geological evidence of the most recent earthquakes. The results also highlight the importance of applying multiple geophysical techniques in defining the location of buried faults.

  4. Inferring Earthquake Physics from Deep Drilling Projects of Active Faults

    NASA Astrophysics Data System (ADS)

    Di Toro, G.; Smith, S. A. F.; Kuo, L. W.; Mittempergher, S.; Remitti, F.; Spagnuolo, E.; Mitchell, T. M.; Gualtieri, A.; Hadizadeh, J.; Carpenter, B. M.

    2014-12-01

    Deep drilling projects of active faults offer the opportunity to correlate physical and chemical processes identified in core samples with experiments reproducing the seismic cycle in the laboratory and with high-resolution seismological and geophysical data. Here we discuss the constraints about earthquakes source processes at depth gained by fault cores retrieved from the deep drilling projects SAFOD (2.7 km depth, San Andreas Fault), J-FAST (0.9 km depth, following the Mw 9.0 Tohoku 2011 earthquake), TCDP (1.1 km depth, following the Mw 7.6 Chi-Chi 1999 earthquake) and WFSD (1.2 km depth, following the Mw 7.9 Wenchuan 2008 earthquake). Recovered samples were tested at room temperature with the rotary shear apparatus SHIVA installed in Rome (INGV, Italy). All the tested samples were made by clay-rich gouges (usually including smectite/illite), though their bulk mineralogy and modal composition were different (e.g., SAFOD samples included saponite, WFSD carbonaceous materials). The gouges were investigated before and after the experiments with scanning and transmission electron microscopy, X-Ray diffraction, micro-Raman spectroscopy, etc. A common behavior of all the tested gouges was that their friction coefficient was low (often less than 0.1) under room-humidity and wet conditions when sheared at slip rates of ca. 1 m/s (seismic deformation conditions). Moreover, when the natural fault rocks next to the principal slipping zones were sheared from sub-seismic (few micrometers/s) to seismic slip rates, the experimental products had similar microstructures to those found in the principal slipping zones of the drilled faults. This included the formation of mirror-like surfaces, graphite-rich materials, foliated gouges, nanograins, amorphous materials, etc. In most cases the mechanical data were consistent with several seismological (> 50 m of seismic slip for the fault zone drilled by J-FAST) and geophysical observations (absence of a thermal anomaly in the fault

  5. Episodic activity of a dormant fault in tectonically stable Europe: The Rauw fault (NE Belgium)

    NASA Astrophysics Data System (ADS)

    Verbeeck, Koen; Wouters, Laurent; Vanneste, Kris; Camelbeeck, Thierry; Vandenberghe, Dimitri; Beerten, Koen; Rogiers, Bart; Schiltz, Marco; Burow, Christoph; Mees, Florias; De Grave, Johan; Vandenberghe, Noël

    2017-03-01

    Our knowledge about large earthquakes in stable continental regions comes from studies of faults that generated historical surface rupturing earthquakes or were identified by their recent imprint in the morphology. Here, we evaluate the co-seismic character and movement history of the Rauw fault in Belgium, which lacks geomorphological expression and historical/present seismicity. This 55-km-long normal fault, with known Neogene and possibly Early Pleistocene activity, is the largest offset fault west of the active Roer Valley Graben. Its trace was identified in the shallow subsurface based on high resolution geophysics. All the layers within the Late Pliocene Mol Formation (3.6 to 2.59 Ma) are displaced 7 m vertically, without growth faulting, but deeper deposits show increasing offset. A paleoseismic trench study revealed cryoturbated, but unfaulted, late glacial coversands overlying faulted layers of Mol Formation. In-between those deposits, the fault tip was eroded, along with evidence for individual displacement events. Fragmented clay gouge observed in a micromorphology sample of the main fault evidences co-seismic faulting, as opposed to fault creep. Based on optical and electron spin resonance dating and trench stratigraphy, the 7 m combined displacement is bracketed to have occurred between 2.59 Ma and 45 ka. The regional presence of the Sterksel Formation alluvial terrace deposits, limited to the hanging wall of the Rauw fault, indicates a deflection of the Meuse/Rhine confluence (1.0 to 0.5 Ma) by the fault's activity, suggesting that most of the offset occurred prior to/at this time interval. In the trench, Sterksel Formation is eroded but reworked gravel testifies for its former presence. Hence, the Rauw fault appears as typical of plate interior context, with an episodic seismic activity concentrated between 1.0 and 0.5 Ma or at least between 2.59 Ma to 45 ka, possibly related to activity variations in the adjacent, continuously active Roer Valley

  6. 42 CFR 411.39 - Automobile and liability insurance (including self-insurance), no-fault insurance, and workers...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...-insurance), no-fault insurance, and workers' compensation: Final conditional payment amounts via Web portal... (including self-insurance), no-fault insurance, and workers' compensation: Final conditional payment amounts...). (2) No fault insurance. (3) Workers' compensation laws or plans. Medicare Secondary Payer...

  7. Quaternary Geology and Surface Faulting Hazard: Active and Capable Faults in Central Apennines, Italy

    NASA Astrophysics Data System (ADS)

    Falcucci, E.; Gori, S.

    2015-12-01

    The 2009 L'Aquila earthquake (Mw 6.1), in central Italy, raised the issue of surface faulting hazard in Italy, since large urban areas were affected by surface displacement along the causative structure, the Paganica fault. Since then, guidelines for microzonation were drew up that take into consideration the problem of surface faulting in Italy, and laying the bases for future regulations about related hazard, similarly to other countries (e.g. USA). More specific guidelines on the management of areas affected by active and capable faults (i.e. able to produce surface faulting) are going to be released by National Department of Civil Protection; these would define zonation of areas affected by active and capable faults, with prescriptions for land use planning. As such, the guidelines arise the problem of the time interval and general operational criteria to asses fault capability for the Italian territory. As for the chronology, the review of the international literature and regulatory allowed Galadini et al. (2012) to propose different time intervals depending on the ongoing tectonic regime - compressive or extensional - which encompass the Quaternary. As for the operational criteria, the detailed analysis of the large amount of works dealing with active faulting in Italy shows that investigations exclusively based on surface morphological features (e.g. fault planes exposition) or on indirect investigations (geophysical data), are not sufficient or even unreliable to define the presence of an active and capable fault; instead, more accurate geological information on the Quaternary space-time evolution of the areas affected by such tectonic structures is needed. A test area for which active and capable faults can be first mapped based on such a classical but still effective methodological approach can be the central Apennines. Reference Galadini F., Falcucci E., Galli P., Giaccio B., Gori S., Messina P., Moro M., Saroli M., Scardia G., Sposato A. (2012). Time

  8. Active faulting on the Wallula fault within the Olympic-Wallowa Lineament (OWL), eastern Washington State

    NASA Astrophysics Data System (ADS)

    Sherrod, B. L.; Lasher, J. P.; Barnett, E. A.

    2013-12-01

    Several studies over the last 40 years focused on a segment of the Wallula fault exposed in a quarry at Finley, Washington. The Wallula fault is important because it is part of the Olympic-Wallowa lineament (OWL), a ~500-km-long topographic and structural lineament extending from Vancouver Island, British Columbia to Walla Walla, Washington that accommodates Basin and Range extension. The origin and nature of the OWL is of interest because it contains potentially active faults that are within 50 km of high-level nuclear waste facilities at the Hanford Site. Mapping in the 1970's and 1980's suggested the Wallula fault did not offset Holocene and late Pleistocene deposits and is therefore inactive. New exposures of the Finley quarry wall studied here suggest otherwise. We map three main packages of rocks and sediments in a ~10 m high quarry exposure. The oldest rocks are very fine grained basalts of the Columbia River Basalt Group (~13.5 Ma). The next youngest deposits include a thin layer of vesicular basalt, white volcaniclastic deposits, colluvium containing clasts of vesicular basalt, and indurated paleosols. A distinct angular unconformity separates these vesicular basalt-bearing units from overlying late Pleistocene flood deposits, two colluvium layers containing angular clasts of basalt, and Holocene tephra-bearing loess. A tephra within the loess likely correlates to nearby outcrops of Mazama ash. We recognize three styles of faults: 1) a near vertical master reverse or oblique fault juxtaposing very fine grained basalt against late Tertiary-Holocene deposits, and marked by a thick (~40 cm) vertical seam of carbonate cemented breccia; 2) subvertical faults that flatten upwards and displace late Tertiary(?) to Quaternary(?) soils, colluvium, and volcaniclastic deposits; and 3) flexural slip faults along bedding planes in folded deposits in the footwall. We infer at least two Holocene earthquakes from the quarry exposure. The first Holocene earthquake deformed

  9. Automatic reconstruction of fault networks from seismicity catalogs including location uncertainty

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Ouillon, G.; Woessner, J.; Sornette, D.; Husen, S.

    2013-11-01

    introduce the anisotropic clustering of location uncertainty distributions (ACLUD) method to reconstruct active fault networks on the basis of both earthquake locations and their estimated individual uncertainties. After a massive search through the large solution space of possible reconstructed fault networks, we apply six different validation procedures in order to select the corresponding best fault network. Two of the validation steps (cross validation and Bayesian information criterion (BIC) process the fit residuals, while the four others look for solutions that provide the best agreement with independently observed focal mechanisms. Tests on synthetic catalogs allow us to qualify the performance of the fitting method and of the various validation procedures. The ACLUD method is able to provide solutions that are close to the expected ones, especially for the BIC and focal mechanism-based techniques. The clustering method complemented by the validation step based on focal mechanisms provides good solutions even in the presence of a significant spatial background seismicity rate. Our new fault reconstruction method is then applied to the Landers area in Southern California and compared with previous clustering methods. The results stress the importance of taking into account undersampled subfault structures as well as of the spatially inhomogeneous location uncertainties.

  10. Active Fault Characterization in the Urban Area of Vienna

    NASA Astrophysics Data System (ADS)

    Decker, Kurt; Grupe, Sabine; Hintersberger, Esther

    2016-04-01

    The identification of active faults that lie beneath a city is of key importance for seismic hazard assessment. Fault mapping and characterization in built-up areas with strong anthropogenic overprint is, however, a challenging task. Our study of Quaternary faults in the city of Vienna starts from the re-assessment of a borehole database of the municipality containing several tens of thousands of shallow boreholes. Data provide tight constraints on the geometry of Quaternary deposits and highlight several locations with fault-delimited Middle to Late Pleistocene terrace sediments of the Danube River. Additional information is obtained from geological descriptions of historical outcrops which partly date back to about 1900. The latter were found to be particularly valuable by providing unprejudiced descriptions of Quaternary faults, sometimes with stunning detail. The along-strike continuations of some of the identified faults are further imaged by industrial 2D/3D seismic acquired outside the city limits. The interpretation and the assessment of faults identified within the city benefit from a very well constrained tectonic model of the active Vienna Basin fault system which derived from data obtained outside the city limits. This data suggests that the urban faults are part of a system of normal faults compensating fault-normal extension at a releasing bend of the sinistral Vienna Basin Transfer Fault. Slip rates estimated for the faults in the city are in the range of several hundredths of millimetres per year and match the slip rates of normal faults that were trenched outside the city. The lengths/areas of individual faults estimated from maps and seismic reach up to almost 700 km² suggesting that all of the identified faults are capable of producing earthquakes with magnitudes M>6, some with magnitudes up to M~6.7.

  11. Relative tectonic activity assessment along the East Anatolian strike-slip fault, Eastern Turkey

    NASA Astrophysics Data System (ADS)

    Khalifa, Abdelrahman

    2016-04-01

    The East Anatolian transform fault is a morphologically distinct and seismically active left-lateral strike-slip fault that extends for ~ 500 km from Karlıova to the Maraş defining the boundary between the Anatolian Block and Syrian Foreland. Deformed landforms along the East Anatolian fault provide important insights into the nature of landscape development within an intra-continental strike-slip fault system. Geomorphic analysis of the East Anatolian fault using geomorphic indices including mountain front sinuosity, stream length-gradient index, drainage density, hypsometric integral, and the valley-width to valley height ratio helped differentiate the faulting into segments of differing degrees of the tectonic and geomorphic activity. Watershed maps for the East Anatolian fault showing the relative relief, incision, and maturity of basins along the fault zone help define segments of the higher seismic risk and help evaluate the regional seismic hazard. The results of the geomorphic indices show a high degree of activity, reveal each segment along the fault is active and represent a higher seismic hazard along the entire fault.

  12. Illuminating Northern California’s Active Faults

    USGS Publications Warehouse

    Prentice, Carol S.; Crosby, Christopher J.; Whitehill, Caroline S.; Arrowsmith, J. Ramon; Furlong, Kevin P.; Philips, David A.

    2009-01-01

    Newly acquired light detection and ranging (lidar) topographic data provide a powerful community resource for the study of landforms associated with the plate boundary faults of northern California (Figure 1). In the spring of 2007, GeoEarthScope, a component of the EarthScope Facility construction project funded by the U.S. National Science Foundation, acquired approximately 2000 square kilometers of airborne lidar topographic data along major active fault zones of northern California. These data are now freely available in point cloud (x, y, z coordinate data for every laser return), digital elevation model (DEM), and KMZ (zipped Keyhole Markup Language, for use in Google EarthTM and other similar software) formats through the GEON OpenTopography Portal (http://www.OpenTopography.org/data). Importantly, vegetation can be digitally removed from lidar data, producing high-resolution images (0.5- or 1.0-meter DEMs) of the ground surface beneath forested regions that reveal landforms typically obscured by vegetation canopy (Figure 2)

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  14. Extreme Hydrothermal Conditions Near an Active Geological Fault, DFDP-2B Borehole, Alpine Fault, New Zealand

    NASA Astrophysics Data System (ADS)

    Sutherland, R.; Townend, J.; Toy, V.; Allen, M.; Baratin, L. M.; Barth, N. C.; Beacroft, L.; Benson, A.; Boese, C. M.; Boles, A.; Boulton, C. J.; Capova, L.; Carpenter, B. M.; Celerier, B. P.; Chamberlain, C. J.; Conze, R.; Cooper, A.; Coussens, J.; Coutts, A.; Cox, S.; Craw, L.; Doan, M. L.; Eccles, J. D.; Faulkner, D.; Grieve, J.; Grochowski, J.; Gulley, A.; Henry, G.; Howarth, J. D.; Jacobs, K. M.; Jeppson, T.; Kato, N.; Keys, S.; Kirilova, M.; Kometani, Y.; Lukács, A.; Langridge, R.; Lin, W.; Little, T.; Mallyon, D.; Mariani, E.; Marx, R.; Massiot, C.; Mathewson, L.; Melosh, B.; Menzies, C. D.; Moore, J.; Morales, L. F. G.; Morgan, C.; Mori, H.; Niemeijer, A. R.; Nishikawa, O.; Nitsch, O.; Paris Cavailhes, J.; Pooley, B.; Prior, D. J.; Pyne, A.; Sauer, K. M.; Savage, M. K.; Schleicher, A.; Schmitt, D. R.; Shigematsu, N.; Taylor-Offord, S.; Tobin, H. J.; Upton, P.; Valdez, R. D.; Weaver, K.; Wiersberg, T.; Williams, J. N.; Yeo, S.; Zimmer, M.; Broderick, N.

    2015-12-01

    The DFDP-2B borehole sampled rocks above and within the upper part of the Alpine Fault, New Zealand, to a depth of 893 m in late 2014. The experiment was the first to drill a major geological fault zone that is active and late in its earthquake cycle. We determined ambient fluid pressures 8-10% above hydrostatic and a geothermal gradient of 130-150 °C/km in rocks above the fault. These unusual ambient conditions can be explained by a combination of: rock advection that transports heat from depth by uplift and oblique slip on the fault; and fluid advection through fractured rock, driven by topographic forcing, which concentrates heat and causes fluid over-pressure in the valley. Highly-anomalous ambient conditions can exist in the vicinity of active faults, and earthquake and mineralization processes occur within these zones.

  15. Active faults of the Baikal depression

    USGS Publications Warehouse

    Levi, K.G.; Miroshnichenko, A.I.; San'kov, V. A.; Babushkin, S.M.; Larkin, G.V.; Badardinov, A.A.; Wong, H.K.; Colman, S.; Delvaux, D.

    1997-01-01

    The Baikal depression occupies a central position in the system of the basins of the Baikal Rift Zone and corresponds to the nucleus from which the continental lithosphere began to open. For different reasons, the internal structure of the Lake Baikal basin remained unknown for a long time. In this article, we present for the first time a synthesis of the data concerning the structure of the sedimentary section beneath Lake Baikal, which were obtained by complex seismic and structural investigations, conducted mainly from 1989 to 1992. We make a brief description of the most interesting seismic profiles which provide a rough idea of a sedimentary unit structure, present a detailed structural interpretation and show the relationship between active faults in the lake, heat flow anomalies and recent hydrothermalism.

  16. Hydrogen Gas Emissions from Active Faults and Identification of Flow Pathway in a Fault Zone

    NASA Astrophysics Data System (ADS)

    Ishimaru, T.; Niwa, M.; Kurosawa, H.; Shimada, K.

    2010-12-01

    It has been observed that hydrogen gas emissions from the subsurface along active faults exceed atmospheric concentrations (e.g. Sugisaki et. al., 1983). Experimental studies have shown that hydrogen gas is generated in a radical reaction of water with fractured silicate minerals due to rock fracturing caused by fault movement (e.g. Kita et al., 1982). Based on such research, we are studying an investigation method for an assessment of fault activity using hydrogen gas emissions from fracture zones. To start, we have devised portable equipment for rapid and simple in situ measurement of hydrogen gas emissions (Shimada et al., 2008). The key component of this equipment is a commercially available and compact hydrogen gas sensor with an integral data logger operable at atmospheric pressure. In the field, we have drilled shallow boreholes into incohesive fault rocks to depths ranging from 15 to 45 cm using a hand-operated drill with a 9mm drill-bit. Then, we have measured the hydrogen gas concentrations in emissions from active faults such as: the western part of the Atotsugawa fault zone, the Atera fault zone and the Neodani fault in central Japan; the Yamasaki fault zone in southwest Japan; and the Yamagata fault zone in northeast Japan. In addition, we have investigated the hydrogen gas concentrations in emissions from other major geological features such as tectonic lines: the Butsuzo Tectonic Line in the eastern Kii Peninsula and the Atokura Nappe in the Northeastern Kanto Mountains. As a result of the investigations, hydrogen gas concentration in emissions from the active faults was measured to be in the approximate range from 6,000 ppm to 26,000 ppm in two to three hours after drilling. A tendency for high concentrations of hydrogen gas in active faults was recognized, in contrast with low concentrations in emissions from tectonic lines that were observed to be in the range from 730 ppm to 2,000 ppm. It is inferred that the hydrogen gas migrates to ground

  17. Earthquake source parameters at the sumatran fault zone: Identification of the activated fault plane

    NASA Astrophysics Data System (ADS)

    Kasmolan, Madlazim; Santosa, Bagus Jaya; Lees, Jonathan M.; Utama, Widya

    2010-12-01

    Fifteen earthquakes (Mw 4.1-6.4) occurring at ten major segments of the Sumatran Fault Zone (SFZ) were analyzed to identify their respective fault planes. The events were relocated in order to assess hypocenter uncertainty. Earthquake source parameters were determined from three-component local waveforms recorded by IRIS-DMC and GEOFON broadband lA networks. Epicentral distances of all stations were less than 10°. Moment tensor solutions of the events were calculated, along with simultaneous determination of centroid position. Joint analysis of hypocenter position, centroid position, and nodal planes produced clear outlines of the Sumatran fault planes. The preferable seismotectonic interpretation is that the events activated the SFZ at a depth of approximately 14-210 km, corresponding to the interplate Sumatran fault boundary. The identification of this seismic fault zone is significant to the investigation of seismic hazards in the region.

  18. Kinematic ground motion simulations on rough faults including effects of 3D stochastic velocity perturbations

    USGS Publications Warehouse

    Graves, Robert; Pitarka, Arben

    2016-01-01

    We describe a methodology for generating kinematic earthquake ruptures for use in 3D ground‐motion simulations over the 0–5 Hz frequency band. Our approach begins by specifying a spatially random slip distribution that has a roughly wavenumber‐squared fall‐off. Given a hypocenter, the rupture speed is specified to average about 75%–80% of the local shear wavespeed and the prescribed slip‐rate function has a Kostrov‐like shape with a fault‐averaged rise time that scales self‐similarly with the seismic moment. Both the rupture time and rise time include significant local perturbations across the fault surface specified by spatially random fields that are partially correlated with the underlying slip distribution. We represent velocity‐strengthening fault zones in the shallow (<5  km) and deep (>15  km) crust by decreasing rupture speed and increasing rise time in these regions. Additional refinements to this approach include the incorporation of geometric perturbations to the fault surface, 3D stochastic correlated perturbations to the P‐ and S‐wave velocity structure, and a damage zone surrounding the shallow fault surface characterized by a 30% reduction in seismic velocity. We demonstrate the approach using a suite of simulations for a hypothetical Mw 6.45 strike‐slip earthquake embedded in a generalized hard‐rock velocity structure. The simulation results are compared with the median predictions from the 2014 Next Generation Attenuation‐West2 Project ground‐motion prediction equations and show very good agreement over the frequency band 0.1–5 Hz for distances out to 25 km from the fault. Additionally, the newly added features act to reduce the coherency of the radiated higher frequency (f>1  Hz) ground motions, and homogenize radiation‐pattern effects in this same bandwidth, which move the simulations closer to the statistical characteristics of observed motions as illustrated by comparison with recordings from

  19. Spacing and strength of active continental strike-slip faults

    NASA Astrophysics Data System (ADS)

    Zuza, Andrew V.; Yin, An; Lin, Jessica; Sun, Ming

    2017-01-01

    Parallel and evenly-spaced active strike-slip faults occur widely in nature across diverse tectonic settings. Despite their common existence, the fundamental question of what controls fault spacing remains unanswered. Here we present a mechanical model for the generation of parallel strike-slip faults that relates fault spacing to the following parameters: (1) brittle-crust thickness, (2) fault strength, (3) crustal strength, and (4) crustal stress state. Scaled analogue experiments using dry sand, dry crushed walnut shells, and viscous putty were employed to test the key assumptions of our quantitative model. The physical models demonstrate that fault spacing (S) is linearly proportional to brittle-layer thickness (h), both in experiments with only brittle materials and in two-layer trials involving dry sand overlying viscous putty. The S / h slope in the two-layer sand-putty experiments may be controlled by the (1) rheological/geometric properties of the viscous layer, (2) effects of distributed basal loading caused by the viscous shear of the putty layer, and/or (3) frictional interaction at the sand-putty interface (i.e., coupling between the viscous and brittle layers). We tentatively suggest that this third effect exerts the strongest control on fault spacing in the analogue experiments. By applying our quantitative model to crustal-scale strike-slip faults using fault spacing and the seismogenic-zone thickness obtained from high-resolution earthquake-location data, we estimate absolute fault friction of active strike-slip faults in Asia and along the San Andreas fault system in California. We show that the average friction coefficient of strike-slip faults in the India-Asia collisional orogen is lower than that of faults in the San Andreas fault system. Weaker faults explain why deformation penetrates >3500 km into Asia from the Himalaya and why the interior of Asia is prone to large (M > 7.0) devastating earthquakes along major intra-continental strike

  20. Faulting processes in active faults - Evidences from TCDP and SAFOD drill core samples

    SciTech Connect

    Janssen, C.; Wirth, R.; Wenk, H. -R.; Morales, L.; Naumann, R.; Kienast, M.; Song, S. -R.; Dresen, G.

    2014-08-20

    The microstructures, mineralogy and chemistry of representative samples collected from the cores of the San Andreas Fault drill hole (SAFOD) and the Taiwan Chelungpu-Fault Drilling project (TCDP) have been studied using optical microscopy, TEM, SEM, XRD and XRF analyses. SAFOD samples provide a transect across undeformed host rock, the fault damage zone and currently active deforming zones of the San Andreas Fault. TCDP samples are retrieved from the principal slip zone (PSZ) and from the surrounding damage zone of the Chelungpu Fault. Substantial differences exist in the clay mineralogy of SAFOD and TCDP fault gouge samples. Amorphous material has been observed in SAFOD as well as TCDP samples. In line with previous publications, we propose that melt, observed in TCDP black gouge samples, was produced by seismic slip (melt origin) whereas amorphous material in SAFOD samples was formed by comminution of grains (crush origin) rather than by melting. Dauphiné twins in quartz grains of SAFOD and TCDP samples may indicate high seismic stress. The differences in the crystallographic preferred orientation of calcite between SAFOD and TCDP samples are significant. Microstructures resulting from dissolution–precipitation processes were observed in both faults but are more frequently found in SAFOD samples than in TCDP fault rocks. As already described for many other fault zones clay-gouge fabrics are quite weak in SAFOD and TCDP samples. Clay-clast aggregates (CCAs), proposed to indicate frictional heating and thermal pressurization, occur in material taken from the PSZ of the Chelungpu Fault, as well as within and outside of the SAFOD deforming zones, indicating that these microstructures were formed over a wide range of slip rates.

  1. Active Fault Geometry and Crustal Deformation Along the San Andreas Fault System Through San Gorgonio Pass, California: The View in 3D From Seismicity

    NASA Astrophysics Data System (ADS)

    Nicholson, C.; Hauksson, E.; Plesch, A.

    2012-12-01

    Understanding the 3D geometry and deformation style of the San Andreas fault (SAF) is critical to accurate dynamic rupture and ground motion prediction models. We use 3D alignments of hypocenter and focal mechanism nodal planes within a relocated earthquake catalog (1981-2011) [Hauksson et al., 2012] to develop improved 3D fault models for active strands of the SAF and adjacent secondary structures. Through San Gorgonio Pass (SGP), earthquakes define a mechanically layered crust with predominantly high-angle strike-slip faults in the upper ~10 km, while at greater depth, intersecting sets of strike-slip, oblique slip and low-angle thrust faults define a wedge-shaped volume deformation of the lower crust. In some places, this interface between upper and lower crustal deformation may be an active detachment fault, and may have controlled the down-dip extent of recent fault rupture. Alignments of hypocenters and nodal planes define multiple principal slip surfaces through SGP, including a through-going steeply-dipping predominantly strike-slip Banning fault strand at depth that upward truncates a more moderately dipping (40°-50°) blind, oblique North Palm Springs fault. The North Palm Springs fault may be the active down-dip extension of the San Gorgonio Pass thrust offset at depth by the principal, through-going Banning strand. In the northern Coachella Valley, seismicity indicates that the Garnet Hill and Banning fault strands are most likely sub-parallel and steeply dipping (~70°NE) to depths of 8-10 km, where they intersect and merge with a stack of moderately dipping to low-angle oblique thrust faults. Gravity and water well data confirm that these faults are sub-parallel and near vertical in the upper 2-3 km. Although the dense wedge of deep seismicity below SGP and largely south of the SAF contains multiple secondary fault sets of different orientations, the predominant fault set appears to be a series of en echelon NW-striking oblique strike-slip faults

  2. Active Fault Tolerant Control for Ultrasonic Piezoelectric Motor

    NASA Astrophysics Data System (ADS)

    Boukhnifer, Moussa

    2012-07-01

    Ultrasonic piezoelectric motor technology is an important system component in integrated mechatronics devices working on extreme operating conditions. Due to these constraints, robustness and performance of the control interfaces should be taken into account in the motor design. In this paper, we apply a new architecture for a fault tolerant control using Youla parameterization for an ultrasonic piezoelectric motor. The distinguished feature of proposed controller architecture is that it shows structurally how the controller design for performance and robustness may be done separately which has the potential to overcome the conflict between performance and robustness in the traditional feedback framework. A fault tolerant control architecture includes two parts: one part for performance and the other part for robustness. The controller design works in such a way that the feedback control system will be solely controlled by the proportional plus double-integral PI2 performance controller for a nominal model without disturbances and H∞ robustification controller will only be activated in the presence of the uncertainties or an external disturbances. The simulation results demonstrate the effectiveness of the proposed fault tolerant control architecture.

  3. Insurance Applications of Active Fault Maps Showing Epistemic Uncertainty

    NASA Astrophysics Data System (ADS)

    Woo, G.

    2005-12-01

    Insurance loss modeling for earthquakes utilizes available maps of active faulting produced by geoscientists. All such maps are subject to uncertainty, arising from lack of knowledge of fault geometry and rupture history. Field work to undertake geological fault investigations drains human and monetary resources, and this inevitably limits the resolution of fault parameters. Some areas are more accessible than others; some may be of greater social or economic importance than others; some areas may be investigated more rapidly or diligently than others; or funding restrictions may have curtailed the extent of the fault mapping program. In contrast with the aleatory uncertainty associated with the inherent variability in the dynamics of earthquake fault rupture, uncertainty associated with lack of knowledge of fault geometry and rupture history is epistemic. The extent of this epistemic uncertainty may vary substantially from one regional or national fault map to another. However aware the local cartographer may be, this uncertainty is generally not conveyed in detail to the international map user. For example, an area may be left blank for a variety of reasons, ranging from lack of sufficient investigation of a fault to lack of convincing evidence of activity. Epistemic uncertainty in fault parameters is of concern in any probabilistic assessment of seismic hazard, not least in insurance earthquake risk applications. A logic-tree framework is appropriate for incorporating epistemic uncertainty. Some insurance contracts cover specific high-value properties or transport infrastructure, and therefore are extremely sensitive to the geometry of active faulting. Alternative Risk Transfer (ART) to the capital markets may also be considered. In order for such insurance or ART contracts to be properly priced, uncertainty should be taken into account. Accordingly, an estimate is needed for the likelihood of surface rupture capable of causing severe damage. Especially where a

  4. Estimation of active faulting in a slow deformation area: Culoz fault as a case study (Jura-Western Alps junction).

    NASA Astrophysics Data System (ADS)

    de La Taille, Camille; Jouanne, Francois; Crouzet, Christian; Jomard, Hervé; Beck, Christian; de Rycker, Koen; van Daele, Maarten; Lebourg, Thomas

    2014-05-01

    The north-western Alps foreland is considered as still experiencing distal effects of Alpine collision, resulting in both horizontal and vertical relative displacements. Based on seismological and geodetic surveys, detailed patterns of active faulting (including subsurface décollements, blind ramps and deeper crustal thrusts have been proposed (Thouvenot et al., 1998), underlining the importance of NW-SE left-lateral strike-slip offsets as along the Vuache and Culoz faults (cf. the 1996 Epagny event: M=5.4; Thouvenot et al., 1998 and the 1822 Culoz event I=VII-VIII; Vogt, 1979). In parallel to this tectonic evolution, the last glaciation-deglaciation cycles contributed to develop large and over-deepened lacustrine basins, such as Lake Le Bourget (Perrier, 1980). The fine grain, post LGM (ie post 18 ky), sedimentary infill gives a good opportunity to evidence late quaternary tectonic deformations. This study focuses on the Culoz fault, extending from the Jura to the West, to the Chautagne swamp and through the Lake Le Bourget to the East. Historical earthquakes are known nearby this fault as ie the 1822 Culoz event. The precise location and geometry of the main fault is illustrated but its Eastern termination still needs to be determined. High resolution seismic sections and side-scan sonar images performed in the 90's (Chapron et al., 1996) showed that the Col du Chat and Culoz faults have locally deformed the quaternary sedimentary infill of the lake. These studies, mainly devoted to paleo-climate analysis were not able to determine neither the geometry of the fault, or to quantify the observed deformations. A new campaign devoted to highlight the fault geometry and associated deformation, has been performed in October 2013. Very tight profiles were performed during this high resolution seismic survey using seistec boomer and sparker sources. In several places the rupture reaches the most recent seismic reflectors underlying that these faults were active during

  5. Identifying active faults in Switzerland using relocated earthquake catalogs and optimal anisotropic dynamic clustering

    NASA Astrophysics Data System (ADS)

    Wagner, M.; Wang, Y.; Husen, S.; Woessner, J.; Kissling, E. H.; Ouillon, G.; Giardini, D.; Sornette, D.

    2010-12-01

    Active fault zones are the causal locations of most earthquakes, which release tectonic stresses. Yet, identification and association of faults and earthquakes is not straightforward. On the one hand, many earthquakes occur on faults that are unknown. On the other hand, systematic biases and uncertainties in earthquake locations hamper the association of earthquakes and known faults. We tackle the problem of linking earthquakes to faults by relocating them in a non-linear probabilistic manner and by applying a three-dimensional optimal anisotropic dynamic clustering approach to the relocated events to map fault networks. Non-linear probabilistic earthquake location allows to compute probability density functions that provide the complete probabilistic solution to the earthquake hypocenter location problem, including improved information on location uncertainties. To improve absolute earthquake locations we use a newly developed combined controlled-source seismology and local earthquake tomography model, which allows the use of secondary phases, such as PmP. Dynamic clustering is a very general image processing technique that allows partitioning a set of data points. Our improved optimal anisotropic dynamic clustering technique accounts for uncertainties in earthquake locations by the use of probability density functions, as provided by non-linear probabilistic earthquake location. Hence, number and size of the reconstructed faults is controlled by earthquake location uncertainty. We apply our approach to seismicity in Switzerland to identify active faults in the region. Relocated earthquake catalogs and associated fault networks will be compared to already existing information on faults, such as geological and seismotectonic maps, to derive a more complete picture of active faulting in Switzerland.

  6. Timing of activity of two fault systems on Mercury

    NASA Astrophysics Data System (ADS)

    Galluzzi, V.; Guzzetta, L.; Giacomini, L.; Ferranti, L.; Massironi, M.; Palumbo, P.

    2015-10-01

    Here we discuss about two fault systems found in the Victoria and Shakespeare quadrangles of Mercury. The two fault sets intersect each other and show probable evidence for two stages of deformation. The most prominent system is N-S oriented and encompasses several tens to hundreds of kilometers long and easily recognizable fault segments. The other system strikes NE- SW and encompasses mostly degraded and short fault segments. The structural framework of the studied area and the morphological appearance of the faults suggest that the second system is older than the first one. We intend to apply the buffered crater counting technique on both systems to make a quantitative study of their timing of activity that could confirm the already clear morphological evidence.

  7. Anatomy of a microearthquake sequence on an active normal fault

    PubMed Central

    Stabile, T. A.; Satriano, C.; Orefice, A.; Festa, G.; Zollo, A.

    2012-01-01

    The analysis of similar earthquakes, such as events in a seismic sequence, is an effective tool with which to monitor and study source processes and to understand the mechanical and dynamic states of active fault systems. We are observing seismicity that is primarily concentrated in very limited regions along the 1980 Irpinia earthquake fault zone in Southern Italy, which is a complex system characterised by extensional stress regime. These zones of weakness produce repeated earthquakes and swarm-like microearthquake sequences, which are concentrated in a few specific zones of the fault system. In this study, we focused on a sequence that occurred along the main fault segment of the 1980 Irpinia earthquake to understand its characteristics and its relation to the loading-unloading mechanisms of the fault system. PMID:22606366

  8. Active faults and minor plates in NE Asia

    NASA Astrophysics Data System (ADS)

    Kozhurin, Andrey I.; Zelenin, Egor A.

    2014-05-01

    Stated nearly 40 yr ago the uncertainty with plate boundaries location in NE Asia (Chapman, Solomon, 1976) still remains unresolved. Based on the prepositions that a plate boundary must, first, reveal itself in linear sets of active structures, and, second, be continuous and closed, we have undertaken interpretation of medium-resolution KH-9 Hexagon satellite imageries, mostly in stereoscopic regime, for nearly the entire region of NE Asia. Main findings are as follows. There are two major active fault zones in the region north of the Bering Sea. One of them, the Khatyrka-Vyvenka zone, stretches NE to ENE skirting the Bering Sea from the Kamchatka isthmus to the Navarin Cape. Judging by the kinematics of the Olyutorsky 2006 earthquake fault, the fault zones move both right-laterally and reversely. The second active fault zone, the Lankovaya-Omolon zone, starts close to the NE margin of the Okhotsk Sea and extends NE up to nearly the margin of the Chukcha Sea. The fault zone is mostly right-lateral, with topographically expressed cumulative horizontal offsets amounting to 2.5-2.6 km. There may be a third NE-SW zone between the major two coinciding with the Penzhina Range as several active faults found in the southern termination of the Range indicate. The two active fault zones divide the NE Asia area into two large domains, which both could be parts of the Bering Sea plate internally broken and with uncertain western limit. Another variant implies the Khatyrka-Vyvenka zone as the Bering Sea plate northern limit, and the Lankovaya-Omolon zone as separating an additional minor plate from the North-American plate. The choice is actually not crucial, and more important is that both variants leave the question of where the Bering Sea plate boundary is in Alaska. The Lankovaya-Omolon zone stretches just across the proposed northern boundary of the Okhorsk Sea plate. NW of the zone, there is a prominent left-lateral Ulakhan fault, which is commonly interpreted to be a

  9. Active faulting in the Southwestern Venezuelan Andes and Colombia borderland

    SciTech Connect

    Singer, A.; Beltran, C.; Lugo, M. , Caracas )

    1993-02-01

    In the southern Andes, the Bocono fault shows a progressive disactivation of its right lateral movement, resulting from its attenuation against the transversal system of Bramon and its kinematic connection to the [open quotes]Pamplona indenter,[close quotes] considered as a part of the plate boundary between the Caribbean and South America. Near the Colombian frontier, the velocity of Bocono fault is probably less than 1 mm/yr. Such a decrease is explained because an increasing amount of the 1 cm/yr slip movement of the northern part of the fault is absorbed through a complex branching of the active trace, southwest Merida. Another significative amount of the rate movement of Bocono fault, considered as plate boundary, results absorbed by subparallel active faulting systems located to the east (Uribante and Caparo Systems) and to the west sides (San Simon-Seboruco, and San Pedro-Aguas Calientes-La Don Juana systems). The last system, extending beyond the frontier, shows a particular seimotectonic importance, as a probable source of the 1875 Cucata earthquake. In this way, the weight of the southwestern end of Bocono fault as a seismic source loses importance respect to the northern segment located between la Grita and Merida where the 1610 and 1894 earthquakes occurred, and also as compared to the faults that define the [open quotes]Pamplona indenter[close quotes] like probable source for several other destructive earthquakes.

  10. Spatial radon anomalies on active faults in California

    USGS Publications Warehouse

    King, C.-Y.; King, B.-S.; Evans, William C.; Zhang, W.

    1996-01-01

    Radon emanation has been observed to be anomalously high along active faults in many parts of the world. We tested this relationship by conducting and repeating soil air radon surveys with a portable radon meter across several faults in California. The results confirm the existence of fault-associated radon anomalies, which show characteristic features that may be related to fault structures but vary in time due to other environmental changes, such as rainfall. Across two creeping faults in San Juan Bautista and Hollister, the radon anomalies showed prominent double peaks straddling the fault gouge zone during dry summers, but the peak-to-background ratios diminished after significant rain fall during winter. Across a locked segment of the San Andreas fault near Olema, the anomaly has a single peak located several meters southwest of the slip zone associated with the 1906 San Francisco earthquake. Across two fault segments that ruptured during the magnitude 7.5 Landers earthquake in 1992, anomalously high radon concentration was found in the fractures three weeks after the earthquake. We attribute the fault-related anomalies to a slow vertical gas flow in or near the fault zones. Radon generated locally in subsurface soil has a concentration profile that increases three orders of magnitude from the surface to a depth or several meters; thus an upward flow that brings up deeper and radon-richer soil air to the detection level can cause a significantly higher concentration reading. This explanation is consistent with concentrations of carbon dioxide and oxygen, measured in soil-air samples collected during one of the surveys.

  11. The Meers Fault: Tectonic activity in southwestern Oklahoma

    SciTech Connect

    Ramelli, A.R.; Slemmons, D.B.; Brocoum, S.J.

    1987-03-01

    The Meers Fault in Southwestern Oklahoma is capable of producing large, damaging earthquakes. By comparison to historical events, a minimum of M = 6-3/4 to 7-1/4 could be expected. The most recent surface rupturing event occurred in the late Holocene, and it appears that one or more pre-Holocene events preceded it. Surface rupture length is at least 37 km. Displacements comprising the present-day scarp have left-lateral and high-angle reverse components. Vertical separation of the ground surface reaches 5 m, while lateral separation exceeds the vertical by a ratio of about 3:1 to 5:1, reaching about 20 m. Individual events apparently had maximum displacements of several meters. The Meers Fault may be part of a larger active zone. Based on surface expressions, the Washita Valley, Oklahoma and Potter County, Texas Faults may also have ruptures during the late Quaternary, although not as recently as the Meers Fault. Low sun angle photography in Southwestern Oklahoma revealed no evidence of fault activity, other than that of the Meers Fault, although activity may be concealed by poor preservation or ductile surface deformation. This suggests that additional areas of activity may be sparse and rupture infrequently.

  12. Holocene activity and paleoseismicity of the Selaha Fault, southeastern segment of the strike-slip Xianshuihe Fault Zone, Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Yan, Bing; Lin, Aiming

    2017-01-01

    In this study we examine the Holocene activity, including slip rate and paleoseismicity, of the Selaha Fault, a branch of the left-lateral strike-slip Xianshuihe Fault Zone located along the southeastern segment of the Ganzhi-Yushu-Xianshuihe Fault System (GYXFS) of the Tibetan Plateau. Interpretation of high-resolution images and field investigations reveal that the Selaha Fault is characterized by left-lateral strike-slip faulting with an average horizontal slip-rate of 9.0 mm/year during the Holocene. Trench excavations and 14C dating results show that at least three morphogenic earthquakes occurred during the past millennium; the most recent event occurred in the past 450 years and corresponds to the 1786 M 7.75 earthquake. The penultimate seismic event (E2) occurred in the period between 560 and 820 year BP (i.e., 1166-1428 CE) and is probably associated with the 1327 M 7.5 earthquake. The antepenultimate event (E3) is inferred to have occurred in the period between 820 ± 30 and 950 ± 30 year BP. Our results confirm that the Selaha Fault, as a portion of the GYXFS, plays an important role as a tectonic boundary in releasing the strain energy accumulated during the northeastward motion of the Tibetan Plateau in response to the ongoing northward penetration of the Indian Plate into the Eurasian Plate. The strain energy is released in the form of repeated large earthquakes that are recorded by strike-slip displacements of stream channels and alluvial fans.

  13. Fault mirrors of seismically active faults: A fossil of small earthquakes at shallow depths

    NASA Astrophysics Data System (ADS)

    Kuo, L.; Song, S.; Suppe, J.

    2013-12-01

    Many faults are decorated with naturally polished and glossy surfaces named fault mirrors (FMs) formed during slips. The characterization of FMs is of paramount importance to investigate physico-chemical processes controlling dynamic fault mechanics during earthquakes. Here we present detailed microstructural and mineralogical observations of the FMs from borehole cores of seismically active faults. The borehole cores were recovered from 600 to 800 m depth located in the hanging wall of the Hsiaotungshi fault in Taiwan which ruptured during 1935 Mw7.1 Hsinchu-Taichung earthquake. Scanning electron microscope (SEM) images of FMs show that two distinct textural domains, fault gouge and coated materials (nanograins, melt patchs, and graphite), were cut by a well-defined boundary. Melt patches and graphite, determined by X-ray diffraction (XRD), Transmission electron microscope (TEM), and SEM-EDS analysis, were found to be distributed heterogeneously on the slip surfaces. On the basis of the current kinematic cross section of the Hsiaotungshi fault, all the FMs were exhumed less than 5 km, where ambient temperatures are less than 150°C. It seems that the amorphous materials on the FMs were generated by seismic slips. The sintering nanograins coating the slip surfaces was also suggested to be produced at high slip rates from both natural observation and recent rock deformation experiments. In addition, graphite could be produced by seismic slips and lubricate the fault based on the rock deformation experiments. Our observation suggests that the FMs were composed of several indicators of coseismic events (melt patches, sintering nanograins, and graphite) corresponding to small thermal perturbation generated by seismic slips. Although the contribution of these coseismic indicators on frictional behavior remains largely unknown, it suggests that multiple dynamic weakening mechanisms such as flash heating, powder lubrication and graphitization may be involved during

  14. Mineralogy and porosity transformation induced by normal fault activity, Pirgaki fault zone (Corinth rift, Greece).

    NASA Astrophysics Data System (ADS)

    Géraud, Y.; Diraison, M.

    2003-04-01

    The Pirgaki fault displays an average N095-100 strike direction and contributes to the south part of the Corinth graben. Several interconnected segments compose it and it forms a quite continuous fault scrap elevated up to 300 meters. The total length of outcropping fault zone is at least 30 km. The dip angle involves between 40° to 70° for the highest. The high angle part of the fault marks the contact between limestone and sediments of the rift series (Ghisetti et al. 2001). A large set of structural and sedimentological criteria are evidence of repeated activity of the Pirgaki fault during the whole Pliocene-Pleistocene period (Ghisetti et al., 2001). The studied part of the Pirgaki fault zone has low angle dip and affects limestones. These limestones, as well as in the hanging wall than in the footwall, are strongly affected by a previous neogene orogen with ductile (folds) and brittle (faults) structures. The sampling zone concerns the low dipping part of the fault. A set of 12 samples is analysed by Hg and water porosimetry, X-ray diffraction and SEM. Protolith is characterised by a very low porosity material, porous volume lower than 1% and threshold size lower 0.1µm. Clay fraction of the protolith material is formed by a set of interstratified illite-smectite and kaolinite minerals. The gouge zone is characterized by an important structural modification with formation of ductile strain part and a brittle strain part. Transformations of the clay content are important in this part of the fault zone. Interstratified phases disappear and are replaced by illite and chlorite phases. The highest illite content is measured for the brittle part of the gouge zone and the highest chlorite content is measured in the ductile part. These structural transformations are also associated with porosity modifications with an large increase of the porosity volume (10%) an of the threshold diameter (3µm) in the brittle part and a lower increase (porosity value, 2% and

  15. General Monte Carlo reliability simulation code including common mode failures and HARP fault/error-handling

    NASA Technical Reports Server (NTRS)

    Platt, M. E.; Lewis, E. E.; Boehm, F.

    1991-01-01

    A Monte Carlo Fortran computer program was developed that uses two variance reduction techniques for computing system reliability applicable to solving very large highly reliable fault-tolerant systems. The program is consistent with the hybrid automated reliability predictor (HARP) code which employs behavioral decomposition and complex fault-error handling models. This new capability is called MC-HARP which efficiently solves reliability models with non-constant failures rates (Weibull). Common mode failure modeling is also a specialty.

  16. Nature of Active Traces of the Hayward Fault at the University of California, Berkeley

    NASA Astrophysics Data System (ADS)

    Wells, D. L.; Swan, F. H.; Thompson, S. C.; Baldwin, J. N.; Williams, P. L.; Rubin, R. S.; Lavine, A.; Hall, N. T.

    2007-12-01

    The location of the Hayward fault zone at the University of California Berkeley Campus is well defined by geomorphic features including offset stream channels, side-hill benches, and the break-in-slope at the base of the Berkeley Hills, as well as by fault-creep related deformation of curbs, buried culverts and utilities, and structures--most notably Memorial Stadium. Based on the mapped fault traces associated with these surficial features, more than 30 trenches have been excavated at various locations on the campus during the past twenty years to assess the exact location and width of the active fault zone near existing and planned structures. These trenches show that the active fault trace(s) range from well expressed to poorly expressed in various surficial materials as a function of (1) the local geometry of the fault, (2) the stability of the near-surface deposits (e.g., it is poorly expressed where it crosses active landslides), and (3) the age of the deposits (i.e., it is better expressed in older deposits). At locations near the Smyth-Fernwald Housing, Prospect Court, the Greek Theater, and Foothill Housing, trenches showed that the fault is characterized by multiple distinct traces that in many places bound alluvial/colluvial-filled depressions up to 6 meters wide, and are in-filled with Holocene deposits. Quaternary deposits and bedrock units are truncated, indicating that significant lateral and vertical displacement has occurred along these fault traces. The creeping trace of the fault generally coincides with these well expressed fault traces. Trenches also revealed that two sub-parallel active fault traces as much as 40 to 60 meters apart extend along the hillslope directly east of the Greek Theater and north and east of Bowles Hall. It remains uncertain as to how fault creep occurs along the two separate branches. Between Memorial Stadium and Bowles Hall, there is a small right bend or stepover in the fault. The location of the creeping trace is

  17. Is there really an active fault (Cibyra Fault?) cutting the Stadion of the ancient city of Cibyra? (Burdur-Fethiye Fault Zone, Turkey)

    NASA Astrophysics Data System (ADS)

    Elitez, İrem; Yaltırak, Cenk

    2013-04-01

    The Cibyra segment of the Burdur-Fethiye Fault Zone (BFFZ) is in a tectonically very active region of southwestern Anatolia. The presence of the Cibyra Fault was firstly suggested by Akyüz and Altunel (1997, 2001). Researchers identified traces of historical earthquakes in Cibyra by taking into account the collapsed seat rows on the east side of the stadion as reference. They claimed that the NNE-SSW left lateral fault Cibyra Fault (related to Burdur-Fethiye Fault Zone) continues through Pliocene sediments on both eastern and western sides of the stadion of Cibyra. The questionable left-lateral fault had been examined in detail by ourselves during our 60-days accommodation in the ancient city of Cibyra excavations for the Burdur-Fethiye Fault Zone Project in 2008, 2009 and 2012. A left-lateral offset on the Stadion was firstly mentioned in a study whose aim is to find the traces of Burdur-Fethiye Fault (Akyüz and Altunel, 2001) and many researchers accepted this fault by reference (for example Alçiçek et al. 2002, 2004, 2005, 2006 and Karabacak, 2011). However as a result of the field observations it is understood that there is no fault cutting the Stadion. By the reason of the fact that there are a lot of faults in the region, however the fault that devastated the ancient city is unknown. The deformation traces on the ruins of the ancient city display a seismic movement occured in the region. It is strongly possible that this movement is related to the NE-SW left lateral oblique normal fault named as Cibyra Fault at the northwestern side of the city. Especially the ravages in the eastern part of the city indicate that the deformations are related to ground properties. If the rotation and overturn movement are considered and if both movements are the product of the same earthquake, the real Cibyra Fault is compatible with normal fault with left lateral compenent. After the 2011 excavations and 2012 field studies, the eastern wall of the Stadion showed that

  18. Fault tolerant photodiode and photogate active pixel sensors

    NASA Astrophysics Data System (ADS)

    Jung, Cory; Chapman, Glenn H.; La Haye, Michelle L.; Djaja, Sunjaya; Cheung, Desmond Y. H.; Lin, Henry; Loo, Edward; Audet, Yves R.

    2005-03-01

    As the pixel counts of digital imagers increase, the challenge of maintaining high yields and ensuring reliability over an imager"s lifetime increases. A fault tolerant active pixel sensor (APS) has been designed to meet this need by splitting an APS in half and operating both halves in parallel. The fault tolerant APS will perform normally in the no defect case and will produce approximately half the output for single defects. Thus, the entire signal can be recovered by multiplying the output by two. Since pixels containing multiple defects are rare, this design can correct for most defects allowing for higher production yields. Fault tolerant photodiode and photogate APS" were fabricated in 0.18-micron technology. Testing showed that the photodiode APS could correct for optically induced and electrically induced faults, within experimental error. The photogate APS was only tested for optically induced defects and also corrects for defects within experimental error. Further testing showed that the sensitivity of fault tolerant pixels was approximately 2-3 times more sensitive than the normal pixels. HSpice simulations of the fault tolerant APS circuit did not show increased sensitivity, however an equivalent normal APS circuit with twice width readout and row transistors was 1.90 times more sensitive than a normal pixel.

  19. Fault activation by hydraulic fracturing in western Canada.

    PubMed

    Bao, Xuewei; Eaton, David W

    2016-12-16

    Hydraulic fracturing has been inferred to trigger the majority of injection-induced earthquakes in western Canada, in contrast to the Midwestern United States, where massive saltwater disposal is the dominant triggering mechanism. A template-based earthquake catalog from a seismically active Canadian shale play, combined with comprehensive injection data during a 4-month interval, shows that earthquakes are tightly clustered in space and time near hydraulic fracturing sites. The largest event [moment magnitude (MW) 3.9] occurred several weeks after injection along a fault that appears to extend from the injection zone into crystalline basement. Patterns of seismicity indicate that stress changes during operations can activate fault slip to an offset distance of >1 km, whereas pressurization by hydraulic fracturing into a fault yields episodic seismicity that can persist for months.

  20. Fault activation by hydraulic fracturing in western Canada

    NASA Astrophysics Data System (ADS)

    Bao, Xuewei; Eaton, David W.

    2016-12-01

    Hydraulic fracturing has been inferred to trigger the majority of injection-induced earthquakes in western Canada, in contrast to the Midwestern United States, where massive saltwater disposal is the dominant triggering mechanism. A template-based earthquake catalog from a seismically active Canadian shale play, combined with comprehensive injection data during a 4-month interval, shows that earthquakes are tightly clustered in space and time near hydraulic fracturing sites. The largest event [moment magnitude (MW) 3.9] occurred several weeks after injection along a fault that appears to extend from the injection zone into crystalline basement. Patterns of seismicity indicate that stress changes during operations can activate fault slip to an offset distance of >1 km, whereas pressurization by hydraulic fracturing into a fault yields episodic seismicity that can persist for months.

  1. Sliding mode fault detection and fault-tolerant control of smart dampers in semi-active control of building structures

    NASA Astrophysics Data System (ADS)

    Yeganeh Fallah, Arash; Taghikhany, Touraj

    2015-12-01

    Recent decades have witnessed much interest in the application of active and semi-active control strategies for seismic protection of civil infrastructures. However, the reliability of these systems is still in doubt as there remains the possibility of malfunctioning of their critical components (i.e. actuators and sensors) during an earthquake. This paper focuses on the application of the sliding mode method due to the inherent robustness of its fault detection observer and fault-tolerant control. The robust sliding mode observer estimates the state of the system and reconstructs the actuators’ faults which are used for calculating a fault distribution matrix. Then the fault-tolerant sliding mode controller reconfigures itself by the fault distribution matrix and accommodates the fault effect on the system. Numerical simulation of a three-story structure with magneto-rheological dampers demonstrates the effectiveness of the proposed fault-tolerant control system. It was shown that the fault-tolerant control system maintains the performance of the structure at an acceptable level in the post-fault case.

  2. Identification of recently active faults and folds in Java, Indonesia

    NASA Astrophysics Data System (ADS)

    Marliyani, G. I.; Arrowsmith, R.; Helmi, H.

    2013-12-01

    We analyze the spatial pattern of active deformation in Java, Indonesia with the aim of characterizing the deformation of the upper plate of the subduction zone in this region. The lack of detailed neotectonic studies in Java is mostly because of its relatively low rate of deformation in spite of significant historical seismic activity. In addition, the abundance of young volcanic materials as well as the region's high precipitation rate and vegetation cover obscure structural relationships and prevent reliable estimates of offset along active faults as well as exhumed intra-arc faults. Detailed maps of active faults derived from satellite and field-based neotectonic mapping, paleoseismic data, as well as new data on the fault kinematics and estimates of orientation of principal stresses from volcano morphology characterize recently active faults and folds. The structures in West Java are dominated by strike-slip faulting, while Central and northern part of East Java are dominated by folds and thrusting with minor normal faulting. The structures vary in length from hundreds meters to tens of kilometers and mainly trend N75°E, N8°E with some minor N45°W. Our preliminary mapping indicates that there are no large scale continuous structures in Java, and that instead deformation is distributed over wide areas along small structures. We established several paleoseismic sites along some of the identified structures. We excavated two shallow trenches along the Pasuruan fault, a normal fault striking NW-SE that forms a straight 13 km scarp cutting Pleistocene deltaic deposits of the north shore of East Java. The trenches exposed faulted and folded fluvial, alluvial and colluvial strata that record at least four ground-rupturing earthquakes since the Pleistocene. The Pasuruan site proves its potential to provide a paleoseismic record rarely found in Java. Abundant Quaternary volcanoes are emplaced throughout Java; most of the volcanoes show elongation in N100°E and N20

  3. Structural Analysis of Active North Bozgush Fault Zone (NW Iran)

    NASA Astrophysics Data System (ADS)

    Saber, R.; Isik, V.; Caglayan, A.

    2013-12-01

    NW Iran is one of the seismically active regions between Zagros Thrust Belt at the south and Caucasus at the north. Not only large magnitude historical earthquakes (Ms>7), but also 1987 Bozgush, 1997 Ardebil (Mw 6.1) and 2012 Ahar-Varzagan (Mw 6.4) earthquakes reveal that the region is seismically active. The North Bozgush Fault Zone (NBFZ) in this region has tens of kilometers in length and hundreds of meters in width. The zone has produced some large and destructive earthquakes (1593 M:6.1 and 1883 M:6.2). The NBFZ affects the Cenozoic units and along this zone Eocene units thrusted over Miocene and/or Plio-Quaternary sedimentary units. Together with morphologic features (stream offsets and alluvial fan movements) affecting the young unites reveal that the zone is active. The zone is mainly characterized by strike-slip faults with reverse component and reverse faults. Reverse faults striking N55°-85°E and dip of 40°-50° to the SW while strike-slip faults show right lateral slip with N60°-85°W and N60°-80°E directions. Our structural data analysis in NBFZ indicates that the axis direction of σ2 principal stress is vertical and the stress ratio (R) is 0.12. These results suggest that the tectonic regime along the North Bozgush Fault Zone is transpressive. Obtained other principal stresses (σ1, σ3) results are compatible with stress directions and GPS velocity suggested for NW Iran.

  4. Active faults crossing trunk pipeline routes: some important steps to avoid disaster

    NASA Astrophysics Data System (ADS)

    Besstrashnov, V. M.; Strom, A. L.

    2011-05-01

    Assessment of seismic strong motion hazard produced by earthquakes originating within causative fault zones allows rather low accuracy of localisation of these structures that can be provided by indirect evidence of fault activity. In contrast, the relevant accuracy of localisation and characterisation of active faults, capable of surface rupturing, can be achieved solely by the use of direct evidence of fault activity. This differentiation requires strict definition of what can be classified as "active fault" and the normalisation of methods used for identification and localisation of active faults crossing oil and natural gas trunk pipelines.

  5. Threshold of Geomorphic Detectability Estimated from Geologic Observations of Active Slow-Slipping Strike-Slip Faults

    NASA Astrophysics Data System (ADS)

    Kaneda, H.

    2002-12-01

    Sources of catastrophic earthquakes include not only major active faults, but also slow-slipping ones. However, geomorphic characteristics and long-term seismic behavior of slow-slipping faults have not been well understood, although intensive paleoseismic studies were carried out after the unexpected 1992 Landers and 1999 Hector Mine earthquakes. Two Japanese surface faulting earthquakes on slow-slipping strike-slip faults (the 1927 Mw=7.0 Kita-Tango and 1943 Mw=7.0 Tottori earthquakes) provided good opportunity to examine these problems. Analysis of coseismic surface slip, cumulative geomorphic expressions, and paleoseismicity for these two events not only supports a characteristic-slip behavior for these faults, but also suggests a concept of threshold of geomorphic detectability for intramontane strike-slip faults, which must be exceeded in order that progressive coseismic surface offsets can be preserved against surface processes as detectable systematic deflections of channels and ridge crests. The determined threshold slip rates for these examples are in the range of 0.06-0.13 mm/yr, which can be a quantitative explanation for an extremely small number of mapped active faults with slip rates of less than 0.1 mm/yr in Japan islands. On the contrary, the threshold of geomorphic detectability is probably negligible in arid regions where denudation rate would be extremely low. To date, the issue of geomorphologically undetectable active faults has been that of blind thrust faults buried beneath thick sediments, but another type of blind active faults or fault segments can exist in humid and mountainous regions. In spite of their low slip rates and long recurrence intervals, their potential presence must be considered, especially in regions under the tectonically undeveloped regime, where regional strain is accommodated by many scattered slow-slipping faults.

  6. Holocene activity of the Rose Canyon fault zone in San Diego, California

    NASA Astrophysics Data System (ADS)

    Lindvall, Scott C.; Rockwell, Thomas K.

    1995-12-01

    The Rose Canyon fault zone in San Diego, California, has many well-expressed geomorphic characteristics of an active strike-slip fault, including scarps, offset and deflected drainages and channel walls, pressure ridges, a closed depression, and vegetation lineaments. Geomorphic expression of the fault zone from Mount Soledad south to Mission Bay indicates that the Mount Soledad strand is the most active. A network of trenches excavated across the Mount Soledad strand in Rose Creek demonstrate a minimum of 8.7 m of dextral slip in a distinctive early to middle Holocene gravel-filled channel that crosses the fault zone. The gravel-filled channel was preserved within and east of the fault but was removed west of the fault zone by erosion or possibly grading during development. Consequently, the actual displacement of the channel could be greater than 8.7 m. Radiocarbon dates on detrital charcoal recovered from the sediments beneath the channel yield a maximum calibrated age of about 8.1±0.2 kyr. The minimum amount of slip along with the maximum age yield a minimum slip rate of 1.07±0.03 mm/yr on this strand of the Rose Canyon fault zone for much of Holocene time. Other strands of the Rose Canyon fault zone, which are east and west of our site, may also have Holocene activity. Based on an analysis of the geomorphology of fault traces within the Rose Canyon fault zone, along with the results of our trenching study, we estimate the maximum likely slip rate at about 2 mm/yr and a best estimate of about 1.5 mm/yr. Stratigraphie evidence of at least three events is present during the past 8.1 kyr. The most recent surface rupture displaces the modern A horizon (topsoil), suggesting that this event probably occurred within the past 500 years. Stratigraphie and structural relationships also indicate the occurrence of a scarp-forming event at about 8.1 kyr, prior to deposition of the gravel-filled channel that was used as a piercing line. A third event is indicated by the

  7. Kinematic indicators on active normal faults in Western Turkey

    NASA Astrophysics Data System (ADS)

    Hancock, P. L.; Barka, A. A.

    Quaternary normal fault zones in western Turkey comprise multiple slip planes and zone-parallel layers of fault breccia. They also contain several little-known kinematic indicators that are probably typical of many formed at shallow levels in extending terrains. The recent exhumation by contractors of about 2000 m 2 of slip planes in a SSE-dipping fault zone separating Quaternary colluvium from bedrock carbonates at Yavansu (7 km SE of Kuşadasi) permits an unusually complete inventory of the indicators to be compiled. The most spectacular indicators are metre-scale 69°W-pitching corrugations in slip planes and recemented breccia sheets underlying them. Corrugations, characterized by sinusoidal profiles normal to their long axes and, less commonly, culminations and depression along their axes possibly developed as a result of upwards-propagating slip planes seeking undemanding pathways through heterogeneous fault-precursor breccias that formed in advance of tip lines. Parallel to corrugation long axes are those of gutters, flat-floored, sleep-sided channels a few centimetres wide, probably related to the abrasion of subslip-plane breccia sheets. Centimetre-scale tool tracks scored in the uppermost subslip-plane breccia sheet by resistant colluvial clasts are irregular at their proximal ends but distally they swing into alignment with corrugation axes. Frictional-wear striae, centimetres long but only a few millimetres wide and pitching 78°W, are superimposed on the other slip-parallel lineations. Comb fractures nearly perpendicular to slip planes define an intersection lineation which is normal to corrugation axes. Fault-plane solutions of earthquakes on SSE-dipping active faults in the West Anatolian extensional province indicate that mainly normal, combined with minor dextral slip is the dominant mode, a conclusion in accord with the sense of slip inferred from the indicators exposed on the Yavansu slip planes.

  8. Steady activity of microfractures on geological faults loaded by mining stress

    NASA Astrophysics Data System (ADS)

    Naoi, Makoto; Nakatani, Masao; Otsuki, Kenshiro; Yabe, Yasuo; Kgarume, Thabang; Murakami, Osamu; Masakale, Thabang; Ribeiro, Luiz; Ward, Anthony; Moriya, Hirokazu; Kawakata, Hironori; Durrheim, Raymond; Ogasawara, Hiroshi

    2015-05-01

    Acoustic Emissions (AE) down to MW -4 were recorded at a site 1 km beneath the surface in the Cooke 4 Mine, South Africa. Several planar AE clusters with lateral extent of 10-100 m were identified. Most of them were located several tens of meters away from the mining front, and exhibited steady activity during the analysis period of about two months. Some of the clusters coincided with mapped faults. The planar-cluster AEs were sharply aggregated within a thickness of several decimeters, likely delineating the fracture interface of the fault and its higher-order morphology such as branches, bends, and stepovers. The composite focal mechanism evaluated for each cluster was consistent with slip events on the fracture interface. These results imply that numerous shear microfractures occur steadily on a natural fault surface subjected to a mining-related stress increase. The planar clusters consist of very small AEs (99.7% were smaller than MW -2), exhibiting high b-values much exceeding unity. This contrasts with the more usual b-values of the stope-cluster AEs, which were aggregated within 20 m of the mining front and exhibited a more scattered distribution. The size distribution of microfractures on a fracture interface may directly reflect fine-scale irregularities of the interface. On the other hand, many other mapped faults near the planar AE clusters were not accompanied by AE activities, despite the fact that these quiet faults were subjected to a similar stress history. The presence or absence of AE activities on a fault may reflect different states of the fault, including stress and strength.

  9. The three-dimensional pattern of crustal deformation associated with active normal fault systems observed using continuous GPS geodesy

    NASA Astrophysics Data System (ADS)

    Bennett, R. A.; Hreinsdottir, S.

    2009-12-01

    Geological examples of shallow dipping normal faults with large displacements are exposed at numerous locations throughout the world and it is widely recognized that extensional deformation at brittle crustal levels is most efficiently accomplished by slip across such structures. It has previously been shown that lower dip angles reduce the regional stresses required to drive large horizontal displacements. Nevertheless, the traditional theory of fault mechanics—based on Anderson’s classification of stress regimes, the Coulomb failure criterion, and Byerlee’s friction law—precludes such faults from slipping at low angle. Observational support for this traditional theory includes the absence of large unequivocally low-angle normal fault earthquakes in the global catalog; all well-determined normal fault earthquakes appear to have occurred on moderate to steeply dipping planes. However, precise measurements of 3D crustal motions based on continuous GPS in central Italy and Utah reveal deformation patterns across active normal fault systems that are inconsistent with active slip across steeply dipping planes. Instead, the combination of observed horizontal and vertical surface motions are consistent with slip across low angle surfaces independently imaged in the subsurface by seismic reflection and other geophysical data. For the Alto Tiberina fault in central Italy, active aseismic creep occurs at shallow crustal levels, most likely within the brittle-frictional regime at which Andersonian-Byerlee fault mechanics should be applicable. The actively creeping portion of the fault inferred using GPS geodesy correlates well with the observed pattern of micro-seismicity, which concentrates along the inferred subsurface fault plane. GPS measurements across the greater Wasatch fault zone in the vicinity of Salt Lake City, Utah, reveal crustal motions consistent with aseismic displacement across a shallow dipping fault or sub-horizontal shear zone at mid

  10. Measuring Active Faulting in Bolivia: the 1998 Aiquile Earthquake

    NASA Astrophysics Data System (ADS)

    Funning, G. J.; Barke, R.; Lamb, S. H.; Minaya, E.; Parsons, B. E.; Woodhouse, J. H.

    2003-12-01

    The Aiquile region of central Bolivia is situated in the core of the actively deforming Bolivian Orocline. Palaeomagnetic data show that differential rotations consistent with oblique convergence have continued over the past 10 Myr. Structural mapping of the sub-Andean fold-and-thrust belt to the east shows that the majority of this convergence has occurred there as shortening; however there exists a significant transverse component of motion which must be accommodated as strike-slip faulting elsewhere. Many topographic lineations assumed to be related to strike-slip faulting have been identified in the area around Aiquile, however none has been associated with large earthquakes or demonstrated to be active over the past million years. On 22nd May 1998, a Mw = 6.5 earthquake struck the region, the largest shallow earthquake to occur in Bolivia for 50 years, resulting in over 105 fatalities and rendering thousands homeless in the towns of Aiquile and Totora and their surrounding villages. Seismic observations of the event are inconclusive; the correct orientation and style of the faulting -- either right-lateral strike-slip on a N--S fault, or left-lateral on an E--W fault -- cannot be determined as large uncertainties in earthquake location mean we do not know a priori which of the two nodal planes in the focal mechanism is the fault plane, or upon which structure the earthquake occurred. We present here the first study of a Bolivian earthquake using InSAR. Despite the rugged nature of the terrain in the Aiquile region, with its sharp changes of relief ( ˜ 3000 m over 20 km) -- a consequence of its location between the high Altiplano to the west and the foreland basin to the east -- we demonstrate that by using freely-available SRTM digital elevation data we can correct for topographic artifacts and generate a clear deformation signal. Our preferred model is for slip on a N--S-striking fault, with a location which validates Modified Mercalli Intensity maps

  11. Measuring fault tolerance with the FTAPE fault injection tool

    NASA Technical Reports Server (NTRS)

    Tsai, Timothy K.; Iyer, Ravishankar K.

    1995-01-01

    This paper describes FTAPE (Fault Tolerance And Performance Evaluator), a tool that can be used to compare fault-tolerant computers. The major parts of the tool include a system-wide fault-injector, a workload generator, and a workload activity measurement tool. The workload creates high stress conditions on the machine. Using stress-based injection, the fault injector is able to utilize knowledge of the workload activity to ensure a high level of fault propagation. The errors/fault ratio, performance degradation, and number of system crashes are presented as measures of fault tolerance.

  12. Robotic technologies of the Flight Telerobotic Servicer (FTS) including fault tolerance

    NASA Technical Reports Server (NTRS)

    Chladek, John T.; Craver, William M.

    1994-01-01

    The original FTS concept for Space Station Freedom (SSF) was to provide telerobotic assistance to enhance crew activity and safety and to reduce crew EVA (Extra Vehicular Activity) activity. The first flight of the FTS manipulator systems would demonstrate several candidate tasks and would verify manipulator performance parameters. These first flight tasks included unlocking a SSF Truss Joint, mating/demating a fluid coupling, contact following of a contour board, demonstrating peg-in-hole assembly, and grasping and moving a mass. Future tasks foreseen for the FTS system included ORU (Orbit Replaceable Unit) change-out, Hubble Space Telescope Servicing, Gamma Ray Observatory refueling, and several in-situ SSF servicing and maintenance tasks. Operation of the FTS was planned to evolve from teleoperation to fully autonomous execution of many tasks. This wide range of mission tasks combined with the desire to evolve toward fully autonomy forced several requirements which may seen extremely demanding to the telerobotics community. The FTS requirements appear to have been created to accommodate the open-ended evolution plan such that operational evolution would not be impeded by function limitations. A recommendation arising from the FTS program to remedy the possible impacts from such ambitious requirements is to analyze candidate robotic tasks. Based on these task analyses, operational impacts against development impacts were weighed prior to requirements definition. Many of the FTS requirements discussed in the following sections greatly influenced the development cost and schedule of the FTS manipulator. The FTS manipulator has been assembled at Martin Marietta and is currently in testing. Successful component tests indicate a manipulator which achieves unprecedented performance specifications.

  13. The character and reactivation history of the southern extension of the seismically active Clarendon Linden Fault System, western New York State

    NASA Astrophysics Data System (ADS)

    Jacobi, Robert D.; Fountain, John

    2002-08-01

    Integration of 11 types of data sets enabled us to determine the location, character and fault history of the southern extension of the Clarendon-Linden Fault System (CLF) in southwestern New York State. The data sets utilized include detailed stratigraphic and fracture measurements at more than 1000 sites, soil gas anomalies, seismic reflection profiles, well logs and lineaments on air photos, topographic maps, Landsat and SLAR images. The seismically active CLF consists of as many as 10 parallel, segmented faults across the fault system. The fault segments are truncated by NW-striking cross-strike discontinuities (CSDs). The faults of the CLF and intersecting CSDs form fault blocks that have semi-independent subsidence and uplift histories. East-dipping reflectors in the Precambrian basement indicate the southward continuation of thrusts of the intra-Grenvillian Elzevir-Frontenac Boundary Zone. These thrusts were reactivated during Iapetan rifting as normal (listric) growth faults. In Ordovician Black River to Trenton time, the southern CLF segments experienced a second phase of growth fault activity, with faults displaying a cumulative stratigraphic throw of as much as ˜170 m. Thrusting on the same east-dipping Precambrian reflectors typified the CLF in Taconic (post-Trenton) times. Detailed comparisons among the fault segments show that the fault activity in Silurian and Devonian times generally alternated between the western and central main faults. In Late Devonian time, the fault motion reversed from down-on-the-east to down-on-the-west about the time the Appalachian Basin axis passed across the CLF in its westward migration. The deep Precambrian faults of the CLF were thus reactivated as the Appalachian Basin developed in Acadian times. Finally, the CLF thrust fault imaged on seismic line CLF-1 offsets all bedrock (Devonian) units; thus, significant motion occurred along this fault during Late Acadian, or more likely, Alleghanian time.

  14. Geodetic Network Design and Optimization on the Active Tuzla Fault (Izmir, Turkey) for Disaster Management

    PubMed Central

    Halicioglu, Kerem; Ozener, Haluk

    2008-01-01

    Both seismological and geodynamic research emphasize that the Aegean Region, which comprises the Hellenic Arc, the Greek mainland and Western Turkey is the most seismically active region in Western Eurasia. The convergence of the Eurasian and African lithospheric plates forces a westward motion on the Anatolian plate relative to the Eurasian one. Western Anatolia is a valuable laboratory for Earth Science research because of its complex geological structure. Izmir is a large city in Turkey with a population of about 2.5 million that is at great risk from big earthquakes. Unfortunately, previous geodynamics studies performed in this region are insufficient or cover large areas instead of specific faults. The Tuzla Fault, which is aligned trending NE–SW between the town of Menderes and Cape Doganbey, is an important fault in terms of seismic activity and its proximity to the city of Izmir. This study aims to perform a large scale investigation focusing on the Tuzla Fault and its vicinity for better understanding of the region's tectonics. In order to investigate the crustal deformation along the Tuzla Fault and Izmir Bay, a geodetic network has been designed and optimizations were performed. This paper suggests a schedule for a crustal deformation monitoring study which includes research on the tectonics of the region, network design and optimization strategies, theory and practice of processing. The study is also open for extension in terms of monitoring different types of fault characteristics. A one-dimensional fault model with two parameters – standard strike-slip model of dislocation theory in an elastic half-space – is formulated in order to determine which sites are suitable for the campaign based geodetic GPS measurements. Geodetic results can be used as a background data for disaster management systems. PMID:27873783

  15. Numerical simulation of coastal flooding after potential reactivation of an active normal fault in northern Taiwan

    NASA Astrophysics Data System (ADS)

    Chan, Yu-Chang; Kuo, Chih-Yu; Chang, Kuo-Jen; Chen, Rou-Fei; Hsieh, Yu-Chung

    2016-04-01

    Rapid coastal flooding from seawards may be resulted from storm surge, tsunamis, and sudden land subsidence due to fault activities. Many observations and numerical modeling of flooding have been made for cases resulted from storm surge and tsunami events; however, coastal flooding caused by a potential normal faulting event nearby coastal areas is rarely reported. In addition to the earthquake hazards from fault rupturing and ground shaking, the accompanied hazards of earthquake-induced flooding is also important to be investigated. The Jinshan area in northern Taiwan was reported to have been flooded by a tsunami event in the year of 1867 possibly resulted from the reactivation of the Shanchiao normal fault offshore. Historical records have shown that the Shanchiao Fault that extends from Shulin along the western edge of the Taipei Basin to the town of Jinshan may have also ruptured in the year of 1694. The rupturing event has created a depression on the western side of the Taipei Basin that was later filled by sea water called the Taipei Lake. The geological conditions in northern Taiwan provide an opportunity for numerically simulating the dynamic processes of sea water flooding nearby the coastal area immediately after an earthquake-induced normal faulting event. In this study, we focused on the potential active normal faulting that may occur and result in an expected catastrophic flooding in lowland area of Jinshan in northern Taiwan. We applied the continuum shallow water equation to evaluate the unknown inundation processes including location, extent, velocity and water depths after the flooding initiated and the final state of the flooding event. The modeling results were well compared with borehole observations of the extent of previous flooding events possibly due to tsunami events. In addition, the modeling results may provide a future basis for safety evaluation of the two nuclear power plants nearby the region.

  16. Geodetic Network Design and Optimization on the Active Tuzla Fault (Izmir, Turkey) for Disaster Management.

    PubMed

    Halicioglu, Kerem; Ozener, Haluk

    2008-08-19

    Both seismological and geodynamic research emphasize that the Aegean Region, which comprises the Hellenic Arc, the Greek mainland and Western Turkey is the most seismically active region in Western Eurasia. The convergence of the Eurasian and African lithospheric plates forces a westward motion on the Anatolian plate relative to the Eurasian one. Western Anatolia is a valuable laboratory for Earth Science research because of its complex geological structure. Izmir is a large city in Turkey with a population of about 2.5 million that is at great risk from big earthquakes. Unfortunately, previous geodynamics studies performed in this region are insufficient or cover large areas instead of specific faults. The Tuzla Fault, which is aligned trending NE-SW between the town of Menderes and Cape Doganbey, is an important fault in terms of seismic activity and its proximity to the city of Izmir. This study aims to perform a large scale investigation focusing on the Tuzla Fault and its vicinity for better understanding of the region's tectonics. In order to investigate the crustal deformation along the Tuzla Fault and Izmir Bay, a geodetic network has been designed and optimizations were performed. This paper suggests a schedule for a crustal deformation monitoring study which includes research on the tectonics of the region, network design and optimization strategies, theory and practice of processing. The study is also open for extension in terms of monitoring different types of fault characteristics. A one-dimensional fault model with two parameters - standard strike-slip model of dislocation theory in an elastic half-space - is formulated in order to determine which sites are suitable for the campaign based geodetic GPS measurements. Geodetic results can be used as a background data for disaster management systems.

  17. Crossing Active Faults on the Sakhalin II Onshore Pipeline Route: Pipeline Design and Risk Analysis

    NASA Astrophysics Data System (ADS)

    Mattiozzi, Pierpaolo; Strom, Alexander

    2008-07-01

    Twin oil (20 & 24 inch) and gas (20 & 48 inch) pipeline systems stretching 800 km are being constructed to connect offshore hydrocarbon deposits from the Sakhalin II concession in the North to an LNG plant and oil export terminal in the South of Sakhalin island. The onshore pipeline route follows a regional fault zone and crosses individual active faults at 19 locations. Sakhalin Energy, Design and Construction companies took significant care to ensure the integrity of the pipelines, should large seismic induced ground movements occur during the Operational life of the facilities. Complex investigations including the identification of the active faults, their precise location, their particular displacement values and assessment of the fault kinematics were carried out to provide input data for unique design solutions. Lateral and reverse offset displacements of 5.5 and 4.5 m respectively were determined as the single-event values for the design level earthquake (DLE)—the 1000-year return period event. Within the constraints of a pipeline route largely fixed, the underground pipeline fault crossing design was developed to define the optimum routing which would minimize stresses and strain using linepipe materials which had been ordered prior to the completion of detailed design, and to specify requirements for pipe trenching shape, materials, drainage system, etc. Detailed Design was performed with due regard to actual topography and to avoid the possibility of the trenches freezing in winter, the implementation of specific drainage solutions and thermal protection measures.

  18. Middle to Late Pleistocene activity of the northern Matese fault system (southern Apennines, Italy)

    NASA Astrophysics Data System (ADS)

    Galli, Paolo; Giaccio, Biagio; Messina, Paolo; Peronace, Edoardo; Amato, Vincenzo; Naso, Giuseppe; Nomade, Sebastian; Pereira, Alison; Piscitelli, Sabatino; Bellanova, Jessica; Billi, Andrea; Blamart, Dominique; Galderisi, Antonio; Giocoli, Alessandro; Stabile, Tony; Thil, Francoise

    2017-03-01

    An integrated investigation including geological, geomorphological, geophysical and structural survey, tephra analyses, 14C and 40Ar/39Ar dating, as well as paleoseismic trenching along the N-Matese fault system is presented. The study allowed the characterization of the tectonic mobility of this structure as well as the associated Bojano basin sedimentary-tectonic evolution since the early Middle Pleistocene, providing also new clues concerning the fault historical activity and the associated Mw > 6.5 earthquakes. We have found lines of evidence for > 1 mm/yr slip rate along the presently buried Bojano fault during the mid Middle Pleistocene, and similar rates for the main fault segments paralleling the Matese flanks. The buried Bojano fault significantly slowed down during the last 300 kyr, ceasing its activity before the Holocene. In turn, the segments outcropping along the Matese flanks reactivated at the onset of Late Pleistocene, after a long period of quiescence (480-110 ka), with robust slip rates that would seem even accelerating in post LGM times. Paleoseismic data suggest the occurrence of four Mw > 6.6 earthquakes in the past 3 ka, three of which match the little known 280 BC event, and the devastating 1456 and 1805 earthquakes.

  19. Crossing Active Faults on the Sakhalin II Onshore Pipeline Route: Analysis Methodology and Basic Design

    NASA Astrophysics Data System (ADS)

    Vitali, Luigino; Mattiozzi, Pierpaolo

    2008-07-01

    Twin oil (20 & 24 inch) and gas (20 & 48 inch) pipeline systems stretching 800 km are being constructed to connect offshore hydrocarbon deposits from the Sakhalin II concession in the North to an LNG plant and oil export terminal in the South of Sakhalin island. The onshore pipeline route follows a regional fault zone and crosses individual active faults at 19 locations. Sakhalin Energy, Design and Construction companies took significant care to ensure the integrity of the pipelines, should large seismic induced ground movements occur during the Operational life of the facilities. Complex investigations including the identification of the active faults, their precise location, their particular displacement values and assessment of the fault kinematics were carried out to provide input data for unique design solutions. Lateral and reverse offset displacements of 5.5 and 4.5 m respectively were determined as the single-event values for the design level earthquake (DLE)—the 1000-year return period event. Within the constraints of a pipeline route largely fixed, the underground pipeline fault crossing design was developed to define the optimum routing which would minimize stresses and strain using linepipe materials which had been ordered prior to the completion of detailed design, and to specify requirements for pipe trenching shape, materials, drainage system, etc. This Paper describes the steps followed to formulate the concept of the special trenches and the analytical characteristics of the Model.

  20. Crossing Active Faults on the Sakhalin II Onshore Pipeline Route: Analysis Methodology and Basic Design

    SciTech Connect

    Vitali, Luigino; Mattiozzi, Pierpaolo

    2008-07-08

    Twin oil (20 and 24 inch) and gas (20 and 48 inch) pipeline systems stretching 800 km are being constructed to connect offshore hydrocarbon deposits from the Sakhalin II concession in the North to an LNG plant and oil export terminal in the South of Sakhalin island. The onshore pipeline route follows a regional fault zone and crosses individual active faults at 19 locations. Sakhalin Energy, Design and Construction companies took significant care to ensure the integrity of the pipelines, should large seismic induced ground movements occur during the Operational life of the facilities. Complex investigations including the identification of the active faults, their precise location, their particular displacement values and assessment of the fault kinematics were carried out to provide input data for unique design solutions. Lateral and reverse offset displacements of 5.5 and 4.5 m respectively were determined as the single-event values for the design level earthquake (DLE)--the 1000-year return period event. Within the constraints of a pipeline route largely fixed, the underground pipeline fault crossing design was developed to define the optimum routing which would minimize stresses and strain using linepipe materials which had been ordered prior to the completion of detailed design, and to specify requirements for pipe trenching shape, materials, drainage system, etc. This Paper describes the steps followed to formulate the concept of the special trenches and the analytical characteristics of the Model.

  1. Crossing Active Faults on the Sakhalin II Onshore Pipeline Route: Pipeline Design and Risk Analysis

    SciTech Connect

    Mattiozzi, Pierpaolo; Strom, Alexander

    2008-07-08

    Twin oil (20 and 24 inch) and gas (20 and 48 inch) pipeline systems stretching 800 km are being constructed to connect offshore hydrocarbon deposits from the Sakhalin II concession in the North to an LNG plant and oil export terminal in the South of Sakhalin island. The onshore pipeline route follows a regional fault zone and crosses individual active faults at 19 locations. Sakhalin Energy, Design and Construction companies took significant care to ensure the integrity of the pipelines, should large seismic induced ground movements occur during the Operational life of the facilities. Complex investigations including the identification of the active faults, their precise location, their particular displacement values and assessment of the fault kinematics were carried out to provide input data for unique design solutions. Lateral and reverse offset displacements of 5.5 and 4.5 m respectively were determined as the single-event values for the design level earthquake (DLE) - the 1000-year return period event. Within the constraints of a pipeline route largely fixed, the underground pipeline fault crossing design was developed to define the optimum routing which would minimize stresses and strain using linepipe materials which had been ordered prior to the completion of detailed design, and to specify requirements for pipe trenching shape, materials, drainage system, etc. Detailed Design was performed with due regard to actual topography and to avoid the possibility of the trenches freezing in winter, the implementation of specific drainage solutions and thermal protection measures.

  2. Active fault segments as potential earthquake sources: Inferences from integrated geophysical mapping of the Magadi fault system, southern Kenya Rift

    NASA Astrophysics Data System (ADS)

    Kuria, Z. N.; Woldai, T.; van der Meer, F. D.; Barongo, J. O.

    2010-06-01

    Southern Kenya Rift has been known as a region of high geodynamic activity expressed by recent volcanism, geothermal activity and high rate of seismicity. The active faults that host these activities have not been investigated to determine their subsurface geometry, faulting intensity and constituents (fluids, sediments) for proper characterization of tectonic rift extension. Two different models of extension direction (E-W to ESE-WNW and NW-SE) have been proposed. However, they were based on limited field data and lacked subsurface investigations. In this research, we delineated active fault zones from ASTER image draped on ASTER DEM, together with relocated earthquakes. Subsequently, we combined field geologic mapping, electrical resistivity, ground magnetic traverses and aeromagnetic data to investigate the subsurface character of the active faults. Our results from structural studies identified four fault sets of different age and deformational styles, namely: normal N-S; dextral NW-SE; strike slip ENE-WSW; and sinistral NE-SW. The previous studies did not recognize the existence of the sinistral oblique slip NE-SW trending faults which were created under an E-W extension to counterbalance the NW-SE faults. The E-W extension has also been confirmed from focal mechanism solutions of the swarm earthquakes, which are located where all the four fault sets intersect. Our findings therefore, bridge the existing gap in opinion on neo-tectonic extension of the rift suggested by the earlier authors. Our results from resistivity survey show that the southern faults are in filled with fluid (0.05 and 0.2 Ωm), whereas fault zones to the north contain high resistivity (55-75 Ωm) material. The ground magnetic survey results have revealed faulting activity within active fault zones that do not contain fluids. In addition, the 2D inversion of the four aero-magnetic profiles (209 km long) revealed: major vertical to sub vertical faults (dipping 75-85° east or west); an

  3. Active tectonics of the Seattle fault and central Puget sound, Washington - Implications for earthquake hazards

    USGS Publications Warehouse

    Johnson, S.Y.; Dadisman, S.V.; Childs, J. R.; Stanley, W.D.

    1999-01-01

    We use an extensive network of marine high-resolution and conventional industry seismic-reflection data to constrain the location, shallow structure, and displacement rates of the Seattle fault zone and crosscutting high-angle faults in the Puget Lowland of western Washington. Analysis of seismic profiles extending 50 km across the Puget Lowland from Lake Washington to Hood Canal indicates that the west-trending Seattle fault comprises a broad (4-6 km) zone of three or more south-dipping reverse faults. Quaternary sediment has been folded and faulted along all faults in the zone but is clearly most pronounced along fault A, the northernmost fault, which forms the boundary between the Seattle uplift and Seattle basin. Analysis of growth strata deposited across fault A indicate minimum Quaternary slip rates of about 0.6 mm/yr. Slip rates across the entire zone are estimated to be 0.7-1.1 mm/yr. The Seattle fault is cut into two main segments by an active, north-trending, high-angle, strike-slip fault zone with cumulative dextral displacement of about 2.4 km. Faults in this zone truncate and warp reflections in Tertiary and Quaternary strata and locally coincide with bathymetric lineaments. Cumulative slip rates on these faults may exceed 0.2 mm/yr. Assuming no other crosscutting faults, this north-trending fault zone divides the Seattle fault into 30-40-km-long western and eastern segments. Although this geometry could limit the area ruptured in some Seattle fault earthquakes, a large event ca. A.D. 900 appears to have involved both segments. Regional seismic-hazard assessments must (1) incorporate new information on fault length, geometry, and displacement rates on the Seattle fault, and (2) consider the hazard presented by the previously unrecognized, north-trending fault zone.

  4. 400My of Deformation Along Tibet Active Strike Slip Faults

    NASA Astrophysics Data System (ADS)

    Arnaud, N. O.

    2003-12-01

    While it is widely accepted that strike slip faults in Tibet accommodate a significant part of the tertiary convergence between India and Asia, the true Cenozoic magnitude of the offset is still largely debated. Direct dating of Cenozoic piercing points is the most powerful tool to assess the total offset, but their use is not always possible. Therefore one gets to use older markers although this leads to significant results ONLY at the supreme condition that pre-Cenozoic movement of those markers be accurately known. The Kunlun and Altyn Tagh faults for example form a prominent example of Tibetan presently active fault, but they also constitute geological frontiers between blocks of different geological histories accreted at various times since early Paleozoic. One may thus question how much of the visible offset is indeed Cenozoic. Although deformation facies agree with recent kinematics, multi-geochronological approach indicates a series of events from 280-230 Ma to 120+/-10 Ma. The former may be linked either with suturing of the Qiantang and Kunlun blocks farther to the south, or collision further to the north or east in the Qilian Shan and Bei Shan ranges, while the latter range appears to be growing in importance with ongoing work but is still largely unexplained. Oblique subductions of collision to the north of the Qilian Shan are adequate candidates. Argon loss suggests that deformation was associated to a 250-300° C thermal pulse that lasted 5 to 20 Ma after the onset of movement (Arnaud et al., 2003). Unroofing on all faults occurred much later, around 25 Ma ago when sudden cooling suggests a component of normal faulting (Mock et al., 1999). Strong inheritage was also found along the Ghoza active fault, in central western Tibet. Of course the fact that some of the deformation is much older than the Cretaceous and shares compatible deformation criteria with the present-day deformation leads to false appreciation of the pure Cenozoic offset, potentially

  5. Earthquake Model of the Middle East (EMME) Project: Active Fault Database for the Middle East Region

    NASA Astrophysics Data System (ADS)

    Gülen, L.; Wp2 Team

    2010-12-01

    The Earthquake Model of the Middle East (EMME) Project is a regional project of the umbrella GEM (Global Earthquake Model) project (http://www.emme-gem.org/). EMME project region includes Turkey, Georgia, Armenia, Azerbaijan, Syria, Lebanon, Jordan, Iran, Pakistan, and Afghanistan. Both EMME and SHARE projects overlap and Turkey becomes a bridge connecting the two projects. The Middle East region is tectonically and seismically very active part of the Alpine-Himalayan orogenic belt. Many major earthquakes have occurred in this region over the years causing casualties in the millions. The EMME project will use PSHA approach and the existing source models will be revised or modified by the incorporation of newly acquired data. More importantly the most distinguishing aspect of the EMME project from the previous ones will be its dynamic character. This very important characteristic is accomplished by the design of a flexible and scalable database that will permit continuous update, refinement, and analysis. A digital active fault map of the Middle East region is under construction in ArcGIS format. We are developing a database of fault parameters for active faults that are capable of generating earthquakes above a threshold magnitude of Mw≥5.5. Similar to the WGCEP-2007 and UCERF-2 projects, the EMME project database includes information on the geometry and rates of movement of faults in a “Fault Section Database”. The “Fault Section” concept has a physical significance, in that if one or more fault parameters change, a new fault section is defined along a fault zone. So far over 3,000 Fault Sections have been defined and parameterized for the Middle East region. A separate “Paleo-Sites Database” includes information on the timing and amounts of fault displacement for major fault zones. A digital reference library that includes the pdf files of the relevant papers, reports is also being prepared. Another task of the WP-2 of the EMME project is to prepare

  6. Active Faults and Seismic Sources of the Middle East Region: Earthquake Model of the Middle East (EMME) Project

    NASA Astrophysics Data System (ADS)

    Gulen, L.; EMME WP2 Team*

    2011-12-01

    The Earthquake Model of the Middle East (EMME) Project is a regional project of the GEM (Global Earthquake Model) project (http://www.emme-gem.org/). The EMME project covers Turkey, Georgia, Armenia, Azerbaijan, Syria, Lebanon, Jordan, Iran, Pakistan, and Afghanistan. Both EMME and SHARE projects overlap and Turkey becomes a bridge connecting the two projects. The Middle East region is tectonically and seismically very active part of the Alpine-Himalayan orogenic belt. Many major earthquakes have occurred in this region over the years causing casualties in the millions. The EMME project consists of three main modules: hazard, risk, and socio-economic modules. The EMME project uses PSHA approach for earthquake hazard and the existing source models have been revised or modified by the incorporation of newly acquired data. The most distinguishing aspect of the EMME project from the previous ones is its dynamic character. This very important characteristic is accomplished by the design of a flexible and scalable database that permits continuous update, refinement, and analysis. An up-to-date earthquake catalog of the Middle East region has been prepared and declustered by the WP1 team. EMME WP2 team has prepared a digital active fault map of the Middle East region in ArcGIS format. We have constructed a database of fault parameters for active faults that are capable of generating earthquakes above a threshold magnitude of Mw≥5.5. The EMME project database includes information on the geometry and rates of movement of faults in a "Fault Section Database", which contains 36 entries for each fault section. The "Fault Section" concept has a physical significance, in that if one or more fault parameters change, a new fault section is defined along a fault zone. So far 6,991 Fault Sections have been defined and 83,402 km of faults are fully parameterized in the Middle East region. A separate "Paleo-Sites Database" includes information on the timing and amounts of fault

  7. Safety enhancement of oil trunk pipeline crossing active faults on Sakhalin Island

    NASA Astrophysics Data System (ADS)

    Tishkina, E.; Antropova, N.; Korotchenko, T.

    2015-11-01

    The article explores the issues concerning safety enhancement of pipeline active fault crossing on Sakhalin Island. Based on the complexity and analysis results, all the faults crossed by pipeline system are classified into five categories - from very simple faults to extremely complex ones. The pipeline fault crossing design is developed in accordance with the fault category. To enhance pipeline safety at fault crossing, a set of methods should be applied: use of pipes of different safety classes and special trench design in accordance with soil permeability characteristics.

  8. Quantifying fault-zone activity in arid environments with high-resolution topography

    NASA Astrophysics Data System (ADS)

    Oskin, Michael E.; Le, Kimberly; Strane, Michael D.

    2007-11-01

    High-resolution airborne laser swath-mapping (ALSM) topography illuminates active faulting with unprecedented clarity. We contrast ALSM topography of two dextral faults in arid regions of California with slip rates that differ by an order of magnitude: The Lenwood fault, with rate of ~1 mm/yr, and the Clark fault, a strand of the San Jacinto fault with net slip rate >10 mm/yr. Visualization of ALSM data reveals abundant fault scarps and deflected channels that when reconstructed can yield powerful slip constraints. Though many of these features may also be detected in existing aerial photography, these data are limited by stereo depth resolution and fixed illumination angle.

  9. Searching for Seismically Active Faults in the Gulf of Cadiz

    NASA Astrophysics Data System (ADS)

    Custodio, S.; Antunes, V.; Arroucau, P.

    2015-12-01

    The repeated occurrence of large magnitude earthquakes in southwest Iberia in historical and instrumental times suggests the presence of active fault segments in the region. However, due to an apparently diffuse seismicity pattern defining a broad region of distributed deformation west of Gibraltar Strait, the question of the location, dimension and geometry of such structures is still open to debate. We recently developed a new algorithm for earthquake location in 3D complex media with laterally varying interface depths, which allowed us to relocate 2363 events having occurred from 2007 to 2013, using P- and S-wave catalog arrival times obtained from the Portuguese Meteorological Institute (IPMA, Instituto Portugues do Mar e da Atmosfera), for a study area lying between 8.5˚W and 5˚W in longitude and 36˚ and 37.5˚ in latitude. The most remarkable change in the seismicity pattern after relocation is an apparent concentration of events, in the North of the Gulf of Cadiz, along a low angle northward-dipping plane rooted at the base of the crust, which could indicate the presence of a major fault. If confirmed, this would be the first structure clearly illuminated by seismicity in a region that has unleashed large magnitude earthquakes. Here, we present results from the joint analysis of focal mechanism solutions and waveform similarity between neighboring events from waveform cross-correlation in order to assess whether those earthquakes occur on the same fault plane.

  10. Late Quaternary Activity and Seismogenic Potential of the Gonave Microplate: Plantain Garden Strike-Slip Fault Zone of Eastern Jamaica

    NASA Astrophysics Data System (ADS)

    Mann, P.; Prentice, C.; King, W.; Demets, C.; Wiggins-Grandison, M.; Benford, B.

    2008-12-01

    At the longitude of Jamaica, Caribbean (Carib)-North America (Noam) plate motion of 19 ± 2 mm/a is carried by two parallel, left-lateral strike-slip faults, the Oriente fault zone, immediately south of Cuba, and the Enriquillo-Plantain Garden fault zone (EPGFZ), which lies 100-150 km further south. It has been postulated that the lithosphere between these faults constitutes an independent Gonave microplate that has formed in response to the ongoing collision between the leading edge of Carib in Hispaniola and the Bahama carbonate platform. GPS measurements in Jamaica and Hispanola is supportive of the microplate hypothesis and indicates that roughly half of Carib-Noam plate motion (8-14 mm/a) is carried by the EPGFZ of southern Hispaniola and eastern Jamaica. This study applies geomorphic and paleoseismic methods as a direct test of the activity and amount of microplate motion carried on the Plantain Garden fault segment of eastern Hispaniola and how this motion is distributed across a large restraining bend that has formed the island of Jamaica since the late Miocene. The EPFZ curves gently to the northeast and forming a steep mountain front to the Blue Mountains restraining bend with elevations up to 2200 m. Geomorphic fault-related features along the mountain front fault zone include left-laterally deflected rivers and streams, but no small scale features indicative of Holocene activity. River and stream deflections range from 0.1 to 0.5 km. We identified and trenched the most active trace of the mountain front fault at the Morant River where the fault is characterized by a 1.5-m-wide sub-vertical fault zone juxtaposing sheared alluvium and fault Cretaceous basement rocks This section is overlain by a 6-m-thick fluvial terrace. Trenching in the unfaulted terrace immediately overlying the fault trace revealed radiocarbon and OSL ages ranging from 20 to 21 ka that are consistent with a prominent unfaulted alluvial fan along the projection of this fault 1.5 km to

  11. Aftershocks illuminate the 2011 Mineral, Virginia, earthquake causative fault zone and nearby active faults

    USGS Publications Warehouse

    Horton, Jr., J. Wright; Shah, Anjana K.; McNamara, Daniel E.; Snyder, Stephen L.; Carter, Aina M

    2015-01-01

    Deployment of temporary seismic stations after the 2011 Mineral, Virginia (USA), earthquake produced a well-recorded aftershock sequence. The majority of aftershocks are in a tabular cluster that delineates the previously unknown Quail fault zone. Quail fault zone aftershocks range from ~3 to 8 km in depth and are in a 1-km-thick zone striking ~036° and dipping ~50°SE, consistent with a 028°, 50°SE main-shock nodal plane having mostly reverse slip. This cluster extends ~10 km along strike. The Quail fault zone projects to the surface in gneiss of the Ordovician Chopawamsic Formation just southeast of the Ordovician–Silurian Ellisville Granodiorite pluton tail. The following three clusters of shallow (<3 km) aftershocks illuminate other faults. (1) An elongate cluster of early aftershocks, ~10 km east of the Quail fault zone, extends 8 km from Fredericks Hall, strikes ~035°–039°, and appears to be roughly vertical. The Fredericks Hall fault may be a strand or splay of the older Lakeside fault zone, which to the south spans a width of several kilometers. (2) A cluster of later aftershocks ~3 km northeast of Cuckoo delineates a fault near the eastern contact of the Ordovician Quantico Formation. (3) An elongate cluster of late aftershocks ~1 km northwest of the Quail fault zone aftershock cluster delineates the northwest fault (described herein), which is temporally distinct, dips more steeply, and has a more northeastward strike. Some aftershock-illuminated faults coincide with preexisting units or structures evident from radiometric anomalies, suggesting tectonic inheritance or reactivation.

  12. Discrete element modeling of the faulting in the sedimentary cover above an active salt diapir

    NASA Astrophysics Data System (ADS)

    Yin, Hongwei; Zhang, Jie; Meng, Lingsen; Liu, Yuping; Xu, Shijing

    2009-09-01

    Geological mapping, seismic analyses, and analogue experiments show that active salt diapirism results in significant faulting in the overburden strata. Faults associated with active diapirism generally develop over the crest of the dome and form a radial pattern. In this study, we have created a 3-D discrete element model and used this model to investigate the fault system over active diapirs. The model reproduces some common features observed in physical experiments and natural examples. The discrete element results show that most faults initiate near the model surface and have displacement decreasing downward. In addition, model results indicate that the earliest fault, working as the master fault, has a strong influence on the subsequent fault pattern. The footwall of the master fault is mainly deformed by arc-parallel stretching and develops a subradial fault pattern, whereas the hanging wall is deformed by both arc-parallel stretching and gliding along the master fault and top of salt, and hence develops both parallel and oblique faults. Model results replicate the fault pattern and deformation mechanism of the Reitbrook dome, Germany.

  13. The northwest trending north Boquerón Bay-Punta Montalva Fault Zone; A through going active fault system in southwestern Puerto Rico

    USGS Publications Warehouse

    Roig‐Silva, Coral Marie; Asencio, Eugenio; Joyce, James

    2013-01-01

    The North Boquerón Bay–Punta Montalva fault zone has been mapped crossing the Lajas Valley in southwest Puerto Rico. Identification of the fault was based upon detailed analysis of geophysical data, satellite images, and field mapping. The fault zone consists of a series of Cretaceous bedrock faults that reactivated and deformed Miocene limestone and Quaternary alluvial fan sediments. The fault zone is seismically active (local magnitude greater than 5.0) with numerous locally felt earthquakes. Focal mechanism solutions suggest strain partitioning with predominantly east–west left-lateral displacements with small normal faults striking mostly toward the northeast. Northeast-trending fractures and normal faults can be found in intermittent streams that cut through the Quaternary alluvial fan deposits along the southern margin of the Lajas Valley, an east–west-trending 30-km-long fault-controlled depression. Areas of preferred erosion within the alluvial fan trend toward the west-northwest parallel to the onland projection of the North Boquerón Bay fault. The North Boquerón Bay fault aligns with the Punta Montalva fault southeast of the Lajas Valley. Both faults show strong southward tilting of Miocene strata. On the western end, the Northern Boquerón Bay fault is covered with flat-lying Holocene sediments, whereas at the southern end the Punta Montalva fault shows left-lateral displacement of stream drainage on the order of a few hundred meters.

  14. Tsunamigenic potential of Mediterranean fault systems and active subduction zones

    NASA Astrophysics Data System (ADS)

    Petricca, Patrizio; Babeyko, Andrey

    2016-04-01

    Since the North East Atlantic and Mediterranean Tsunami Warning System (NEAMTWS) is under development by the European scientific community, it becomes necessary to define guidelines for the characterization of the numerous parameters must be taken into account in a fair assessment of the risk. Definition of possible tectonic sources and evaluation of their potential is one of the principal issues. In this study we systematically evaluate tsunamigenic potential of up-to-now known real fault systems and active subduction interfaces in the NEAMTWS region. The task is accomplished by means of numerical modeling of tsunami generation and propagation. We have simulated all possible uniform-slip ruptures populating fault and subduction interfaces with magnitudes ranging from 6.5 up to expected Mmax. A total of 15810 individual ruptures were processed. For each rupture, a tsunami propagation scenario was computed in linear shallow-water approximation on 1-arc minute bathymetric grid (Gebco_08) implying normal reflection boundary conditions. Maximum wave heights at coastal positions (totally - 23236 points of interest) were recorded for four hours of simulation and then classified according to currently adopted warning level thresholds. The resulting dataset allowed us to classify the sources in terms of their tsunamigenic potential as well as to estimate their minimum tsunamigenic magnitude. Our analysis shows that almost every source in the Mediterranean Sea is capable to produce local tsunami at the advisory level (i.e., wave height > 20 cm) starting from magnitude values of Mw=6.6. In respect to the watch level (wave height > 50 cm), the picture is less homogeneous: crustal sources in south-west Mediterranean as well as East-Hellenic arc need larger magnitudes (around Mw=7.0) to trigger watch levels even at the nearby coasts. In the context of the regional warning (i.e., source-to-coast distance > 100 km) faults also behave more heterogeneously in respect to the minimum

  15. Dense seismic networks as a tool to characterize active faulting in regions of slow deformation

    NASA Astrophysics Data System (ADS)

    Custódio, Susana; Arroucau, Pierre; Carrilho, Fernando; Cesca, Simone; Dias, Nuno; Matos, Catarina; Vales, Dina

    2016-04-01

    The theory of plate tectonics states that the relative motion between lithospheric plates is accommodated at plate boundaries, where earthquakes occur on long faults. However, earthquakes with a wide range of magnitudes also occur both off plate boundaries, in intra-plate settings, and along discontinuous, diffuse plate boundaries. These settings are characterized by low rates of lithospheric deformation. A fundamental limitation in the study of slowly deforming regions is the lack of high-quality observations. In these regions, earthquake catalogs have traditionally displayed diffuse seismicity patterns. The location, geometry and activity rate of faults - all basic parameters for understanding fault dynamics - are usually poorly known. The dense seismic networks deployed in the last years around the world have opened new windows in observational seismology. Although high-magnitude earthquakes are rare in regions of slow deformation, low-magnitude earthquakes are well observable on the time-scale of these deployments. In this presentation, we will show how data from dense seismic deployments can be used to characterize faulting in regions of slow deformation. In particular, we will present the case study of western Iberia, a region undergoing low-rate deformation and which has generated some of the largest earthquakes in Europe, both intraplate (mainland) and interplate (offshore). The methods that we employ include automated earthquake detection methods to lower the completeness magnitude of catalogs, earthquake relocations, focal mechanisms patterns, waveform similarity and clustering analysis.

  16. Imaging the complexity of an active normal fault system: The 1997 Colfiorito (central Italy) case study

    USGS Publications Warehouse

    Chiaraluce, L.; Ellsworth, W.L.; Chiarabba, C.; Cocco, M.

    2003-01-01

    Six moderate magnitude earthquakes (5 < Mw < 6) ruptured normal fault segments of the southern sector of the North Apennine belt (central Italy) in the 1997 Colfiorito earthquake sequence. We study the progressive activation of adjacent and nearby parallel faults of this complex normal fault system using ???1650 earthquake locations obtained by applying a double-difference location method, using travel time picks and waveform cross-correlation measurements. The lateral extent of the fault segments range from 5 to 10 km and make up a broad, ???45 km long, NW trending fault system. The geometry of each segment is quite simple and consists of planar faults gently dipping toward SW with an average dip of 40??-45??. The fault planes are not listric but maintain a constant dip through the entire seismogenic volume, down to 8 km depth. We observe the activation of faults on the hanging wall and the absence of seismicity in the footwall of the structure. The observed fault segmentation appears to be due to the lateral heterogeneity of the upper crust: preexisting thrusts inherited from Neogene's compressional tectonic intersect the active normal faults and control their maximum length. The stress tensor obtained by inverting the six main shock focal mechanisms of the sequence is in agreement with the tectonic stress active in the inner chain of the Apennine, revealing a clear NE trending extension direction. Aftershock focal mechanisms show a consistent extensional kinematics, 70% of which are mechanically consistent with the main shock stress field.

  17. Delineation of Urban Active Faults Using Multi-scale Gravity Analysis in Shenzhen, South China

    NASA Astrophysics Data System (ADS)

    Xu, C.; Liu, X.

    2015-12-01

    In fact, many cities in the world are established on the active faults. As the rapid urban development, thousands of large facilities, such as ultrahigh buildings, supersized bridges, railway, and so on, are built near or on the faults, which may change the balance of faults and induce urban earthquake. Therefore, it is significant to delineate effectively the faults for urban planning construction and social sustainable development. Due to dense buildings in urban area, the ordinary approaches to identify active faults, like geological survey, artificial seismic exploration and electromagnetic exploration, are not convenient to be carried out. Gravity, reflecting the mass distribution of the Earth's interior, provides a more efficient and convenient method to delineate urban faults. The present study is an attempt to propose a novel gravity method, multi-scale gravity analysis, for identifying urban active faults and determining their stability. Firstly, the gravity anomalies are decomposed by wavelet multi-scale analysis. Secondly, based on the decomposed gravity anomalies, the crust is layered and the multilayer horizontal tectonic stress is inverted. Lastly, the decomposed anomalies and the inverted horizontal tectonic stress are used to infer the distribution and stability of main active faults. For validating our method, a case study on active faults in Shenzhen City is processed. The results show that the distribution of decomposed gravity anomalies and multilayer horizontal tectonic stress are controlled significantly by the strike of the main faults and can be used to infer depths of the faults. The main faults in Shenzhen may range from 4km to 20km in the depth. Each layer of the crust is nearly equipressure since the horizontal tectonic stress has small amplitude. It indicates that the main faults in Shenzhen are relatively stable and have no serious impact on planning and construction of the city.

  18. Threshold of geomorphic detectability estimated from geologic observations of active low slip-rate strike-slip faults

    NASA Astrophysics Data System (ADS)

    Kaneda, Heitaro

    2003-03-01

    Sources of catastrophic earthquakes include not only major active faults, but also those with low slip rates. Geologic observations of two Japanese surface-rupturing earthquakes on low slip-rate strike-slip faults (the 1927 Kita-Tango and the 1943 Tottori earthquakes) suggests a concept of ``threshold of geomorphic detectability'' for strike-slip faults in humid mountainous regions. This threshold must be exceeded in order that progressive coseismic surface offset can be preserved as detectable faulted topography that may be otherwise erased by surface processes. The determined threshold minimum slip rates for both examples are about 0.1 mm/yr, which can be a quantitative explanation for lack of recognition and mapping of many active faults with slip rates of less than 0.1 mm/yr in Japan islands. Although this threshold is probably negligible in arid regions, it can produce another type of unrecognized active fault in humid mountainous regions, in addition to blind thrusts beneath thick sediments.

  19. 3D Fault modeling of the active Chittagong-Myanmar fold belt, Bangladesh

    NASA Astrophysics Data System (ADS)

    Peterson, D. E.; Hubbard, J.; Akhter, S. H.; Shamim, N.

    2013-12-01

    The Chittagong-Myanmar fold belt (CMFB), located in eastern Bangladesh, eastern India and western Myanmar, accommodates east-west shortening at the India-Burma plate boundary. Oblique subduction of the Indian Plate beneath the Burma Plate since the Eocene has led to the development of a large accretionary prism complex, creating a series of north-south trending folds. A continuous sediment record from ~55 Ma to the present has been deposited in the Bengal Basin by the Ganges-Brahmaputra-Meghna rivers, providing an opportunity to learn about the history of tectonic deformation and activity in this fold-and-thrust belt. Surface mapping indicates that the fold-and-thrust belt is characterized by extensive N-S-trending anticlines and synclines in a belt ~150-200 km wide. Seismic reflection profiles from the Chittagong and Chittagong Hill Tracts, Bangladesh, indicate that the anticlines mapped at the surface narrow with depth and extend to ~3.0 seconds TWTT (two-way travel time), or ~6.0 km. The folds of Chittagong and Chittagong Hill Tracts are characterized by doubly plunging box-shaped en-echelon anticlines separated by wide synclines. The seismic data suggest that some of these anticlines are cored by thrust fault ramps that extend to a large-scale décollement that dips gently to the east. Other anticlines may be the result of detachment folding from the same décollement. The décollement likely deepens to the east and intersects with the northerly-trending, oblique-slip Kaladan fault. The CMFB region is bounded to the north by the north-dipping Dauki fault and the Shillong Plateau. The tectonic transition from a wide band of E-W shortening in the south to a narrow zone of N-S shortening along the Dauki fault is poorly understood. We integrate surface and subsurface datasets, including topography, geological maps, seismicity, and industry seismic reflection profiles, into a 3D modeling environment and construct initial 3D surfaces of the major faults in this

  20. Active fault and water loading are important factors in triggering earthquake activity around Aswan Lake

    NASA Astrophysics Data System (ADS)

    Kebeasy, R. M.; Gharib, A. A.

    Aswan Lake started impounding in 1964 and reached the highest water level so far in 1978 with a capacity of 133.8 km 3, thus forming the second largest man-made lake in the world. An earthquake of magnitude 5.3 (Ms) took place on 14 November 1981 along the most active part of the E-W Kalabsha fault beneath the Kalabsha bay (the largest bay of the lake). This earthquake was followed by a tremendous number of smaller events that continue till now. A radio-telemetry network of 13 seismic short period stations and a piezometer network of six wells were established around the northern part of the lake. Epicenters were found to cluster around active faults near the lake. The space-time distribution and the relation of the seismicity with the lake water level fluctuations were studied. Six years after flooding the eastern segment of the Kalabsha fault, strong seismicity began following the main shock of 14 November 1981. It occurred four days after the reservoir had reached its seasonal max level. 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 activity (Gebel Marawa area) decreased sharply. Also, 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.

  1. Evolution and dynamics of active faults in southeastern Egyptian Western Desert

    NASA Astrophysics Data System (ADS)

    Abdeen, Mamdouh

    2016-07-01

    Remote sensing data processing and analysis together with interpretation of earthquake data that are followed by extensive field studies on some of the prevailing NS and EW striking faults indicate that these faults have an intimate relationship and were formed synchronously as a conjugate Riedel shears. Parallel to the NS and the EW faults open fractures filled with blown sand dominate the area of study. The Quaternary terraces adjacent to these faults are offset by the faults. Kinematic indicators on the NS striking faults indicate major sinistral (left-lateral) strike slip and minor dip-slip (normal) movement. On the other hand, kinematic indicators on the EW striking faults indicate major dextral (right-lateral) strike slip and minor dip-slip (normal) movement. Paleo-stress analysis of the fault striae measured on the NS and EW faults indicate that these faults were formed under NNE-SSW oriented extension. Instrumental earthquake data analysis shows a comparable extension direction to that derived from field measurements of slickenlineation. These observations indicate that the NS- and EW-striking faults are contemporaneous and are related to the Red Sea rifting that is currently active.

  2. Soil Moisture Active Passive Mission: Fault Management Design Analyses

    NASA Technical Reports Server (NTRS)

    Meakin, Peter; Weitl, Raquel

    2013-01-01

    As a general trend, the complexities of modern spacecraft are increasing to include more ambitious mission goals with tighter timing requirements and on-board autonomy. As a byproduct, the protective features that monitor the performance of these systems have also increased in scope and complexity. Given cost and schedule pressures, there is an increasing emphasis on understanding the behavior of the system at design time. Formal test-driven verification and validation (V&V) is rarely able to test the significant combinatorics of states, and often finds problems late in the development cycle forcing design changes that can be costly. This paper describes the approach the SMAP Fault Protection team has taken to address some of the above-mentioned issues.

  3. High-resolution imagery of active faulting offshore Al Hoceima, Northern Morocco

    NASA Astrophysics Data System (ADS)

    d'Acremont, E.; Gutscher, M.-A.; Rabaute, A.; Mercier de Lépinay, B.; Lafosse, M.; Poort, J.; Ammar, A.; Tahayt, A.; Le Roy, P.; Smit, J.; Do Couto, D.; Cancouët, R.; Prunier, C.; Ercilla, G.; Gorini, C.

    2014-09-01

    Two recent destructive earthquakes in 1994 and 2004 near Al Hoceima highlight that the northern Moroccan margin is one of the most seismically active regions of the Western Mediterranean area. Despite onshore geodetic, seismological and tectonic field studies, the onshore-offshore location and extent of the main active faults remain poorly constrained. Offshore Al Hoceima, high-resolution seismic reflection and swath-bathymetry have been recently acquired during the Marlboro-2 cruise. These data at shallow water depth, close to the coast, allow us to describe the location, continuity and geometry of three active faults bounding the offshore Nekor basin. The well-expressed normal-left-lateral onshore Trougout fault can be followed offshore during several kilometers with a N171°E ± 3° trend. Westward, the Bousekkour-Aghbal normal-left-lateral onshore fault is expressed offshore with a N020°E ± 4° trending fault. The N030°E ± 2° Bokkoya fault corresponds to the western boundary of the Plio-Quaternary offshore Nekor basin in the Al Hoceima bay and seems to define an en échelon tectonic pattern with the Bousekkour-Aghbal fault. We propose that these three faults are part of the complex transtensional system between the Nekor fault and the Al-Idrissi fault zone. Our characterization of the offshore expression of active faulting in the Al Hoceima region is consistent with the geometry and nature of the active fault planes deduced from onshore geomorphological and morphotectonic analyses, as well as seismological, geodetic and geodynamic data.

  4. San Jacinto Fault Zone guided waves: A discrimination for recently active fault strands near Anza, California

    NASA Astrophysics Data System (ADS)

    Li, Yong-Gang; Aki, Keiiti; Vernon, Frank L.

    1997-06-01

    We deployed three 350-m-long eight-element linear seismic arrays in the San Jacinto Fault Zone (SJFZ) near Anza, California, to record microearthquakes starting in August through December 1995. Two arrays were deployed 18 km northwest of Anza, across the Casa Loma fault (CLF) and the Hot Springs fault (HSF) strands of the SJFZ. The third array was deployed across the San Jacinto fault (SJF) in the Anza slip gap. We observed fault zone guided waves characterized by low-frequency, large amplitudes following S waves at the CLF array and the SJF array for earthquakes occurring within the fault zone. However, we did not observe guided waves at the HSF array for any events. The amplitude spectra of these guided waves showed peaks at 4 Hz at the CLF and 6 Hz at the SJF, which decreased sharply with the distance from the fault trace. In contrast, no spectral peaks at frequency lower than 6 Hz were registered at the HSF array. We used a finite difference method to simulate these guided modes as 5 waves trapped in a low-velocity waveguide sandwiched between high-velocity wall rocks. The guided mode data are adequately fit by a waveguide on the CLF with the average width of 120 m and S velocity of 2.5 km/s, about 25% reduced from the S velocity of the surrounding rock; this waveguide becomes 40 to 60 m wide with the 5 velocity of 2.8 km/s in the Anza slip gap. On the other hand, there is not a continuous waveguide on the HSF at depth. Locations of the events with guided modes suggest that the fault plane waveguide extends along the CLF between the towns of San Jacinto and Anza, dipping northeastward at 75°-80° to a depth of about 18 km; it becomes nearly vertical in the Anza gap. We speculate that the existence of a continuous low-velocity waveguide on the CLF can be caused by the rupture of the magnitude 6.9 earthquake on April 21, 1918, occurring near the towns of San Jacinto and Hemet. Further, the lack of a clear waveguide on the HSF suggests that it was not ruptured in

  5. Recently active traces of the Bartlett Springs Fault, California: a digital database

    USGS Publications Warehouse

    Lienkaemper, James J.

    2010-01-01

    The purpose of this map is to show the location of and evidence for recent movement on active fault traces within the Bartlett Springs Fault Zone, California. The location and recency of the mapped traces is primarily based on geomorphic expression of the fault as interpreted from large-scale aerial photography. In a few places, evidence of fault creep and offset Holocene strata in trenches and natural exposures have confirmed the activity of some of these traces. This publication is formatted both as a digital database for use within a geographic information system (GIS) and for broader public access as map images that may be browsed on-line or download a summary map. The report text describes the types of scientific observations used to make the map, gives references pertaining to the fault and the evidence of faulting, and provides guidance for use of and limitations of the map.

  6. Slip rate depth distribution for active faults in Central Italy using numerical models

    NASA Astrophysics Data System (ADS)

    Finocchio, Debora; Barba, Salvatore; Basili, Roberto

    2016-09-01

    Slip rate is a critical parameter for describing geologic and earthquake rates of known active faults. Although faults are inherently three-dimensional surfaces, the paucity of data allows for estimating only the slip rate at the ground surface and often only few values for an entire fault. These values are frequently assumed as proxies or as some average of slip rate at depth. Evidence of geological offset and single earthquake displacement, as well as mechanical requirements, show that fault slip varies significantly with depth. Slip rate should thus vary in a presumably similar way, yet these variations are rarely considered. In this work, we tackle the determination of slip rate depth distributions by applying the finite element method on a 2D vertical section, with stratification and faults, across the central Apennines, Italy. In a first step, we perform a plane-stress analysis assuming visco-elasto-plastic rheology and then search throughout a large range of values to minimize the RMS deviation between the model and the interseismic GPS velocities. Using a parametric analysis, we assess the accuracy of the best model and the sensitivity of its parameters. In a second step, we unlock the faults and let the model simulate 10 kyr of deformation to estimate the fault long-term slip rates. The overall average slip rate at depth is approximately 1.1 mm/yr for normal faults and 0.2 mm/yr for thrust faults. A maximum value of about 2 mm/yr characterizes the Avezzano fault that caused the 1915, Mw 7.0 earthquake. The slip rate depth distribution varies significantly from fault to fault and even between neighbouring faults, with maxima and minima located at different depths. We found uniform distributions only occasionally. We suggest that these findings can strongly influence the forecasting of cumulative earthquake depth distributions based on long-term fault slip rates.

  7. Preservation of amorphous ultrafine material: A proposed proxy for slip during recent earthquakes on active faults

    NASA Astrophysics Data System (ADS)

    Hirono, Tetsuro; Asayama, Satoru; Kaneki, Shunya; Ito, Akihiro

    2016-11-01

    The criteria for designating an “Active Fault” not only are important for understanding regional tectonics, but also are a paramount issue for assessing the earthquake risk of faults that are near important structures such as nuclear power plants. Here we propose a proxy, based on the preservation of amorphous ultrafine particles, to assess fault activity within the last millennium. X-ray diffraction data and electron microscope observations of samples from an active fault demonstrated the preservation of large amounts of amorphous ultrafine particles in two slip zones that last ruptured in 1596 and 1999, respectively. A chemical kinetic evaluation of the dissolution process indicated that such particles could survive for centuries, which is consistent with the observations. Thus, preservation of amorphous ultrafine particles in a fault may be valuable for assessing the fault’s latest activity, aiding efforts to evaluate faults that may damage critical facilities in tectonically active zones.

  8. Preservation of amorphous ultrafine material: A proposed proxy for slip during recent earthquakes on active faults

    PubMed Central

    Hirono, Tetsuro; Asayama, Satoru; Kaneki, Shunya; Ito, Akihiro

    2016-01-01

    The criteria for designating an “Active Fault” not only are important for understanding regional tectonics, but also are a paramount issue for assessing the earthquake risk of faults that are near important structures such as nuclear power plants. Here we propose a proxy, based on the preservation of amorphous ultrafine particles, to assess fault activity within the last millennium. X-ray diffraction data and electron microscope observations of samples from an active fault demonstrated the preservation of large amounts of amorphous ultrafine particles in two slip zones that last ruptured in 1596 and 1999, respectively. A chemical kinetic evaluation of the dissolution process indicated that such particles could survive for centuries, which is consistent with the observations. Thus, preservation of amorphous ultrafine particles in a fault may be valuable for assessing the fault’s latest activity, aiding efforts to evaluate faults that may damage critical facilities in tectonically active zones. PMID:27827413

  9. Active faults in Lebanon : kinematics and interseismic behavior measured from radar interferometry (InSAR)

    NASA Astrophysics Data System (ADS)

    Lasserre, C.; Pinel-Puysségur, B.; Vergnolle, M.; Klinger, Y.; Pathier, E.

    2012-12-01

    The Levant fault system, more than 1000 km-long, marks the limit between the Arabian and Sinaï tectonic plates, extending from the Aqaba gulf in the Red Sea to Turkey. Mostly left-lateral, it forms a transpression zone in Lebanon, associating strike-slip faults such as the Yammouneh fault and thrust faults such as the Mount Lebanon thrust. This fault system in Lebanon is at the origin of large historical earthquakes during the past two thousand years (551 AD on the thrust offshore and 1837 along the Roum fault inland, 1759 along the Rashaia and Sergaya faults). We aim at characterizing the present-day behavior of active faults in Lebanon, in particular the Yammouneh fault which did not break since 1202, to contribute to a better assessment of the seismic hazard in this region. Space geodesy techniques (GPS, InSAR) allow to quantify the present-day displacements across faults (a few mm/yr during the interseismic period), and to model stress loading and relaxation processes during the seismic cycle, at the fault scale and at the regional scale. GPS campaign measurements have been made along profiles perpendicular to the Yammouneh fault. In addition, an important archive of radar images covering Lebanon (acquired by the ERS and Envisat satellites, along descending and ascending orbits) is also available. We process ERS and Envisat radar data to obtain the average interseismic velocity field across faults over the past 15-20 years. Techniques of interferograms networks processing (MuLSAR), atmospheric phase delays correction from global atmospherical models, DEM correction and time series inversion (NSBAS) are used to overcome the main remaining limitations in the measurements accuracy (low coherence, strong atmospheric delays, long wavelength deformation signal). The final goal is to propose a modelling of the surface displacement field to quantify the present-day kinematics of active fauts in Lebanon, taking into account GPS data as well as tectonic and

  10. Active Faults, Modern Seismicity And Block Structure Of Eurasia

    NASA Astrophysics Data System (ADS)

    Gatinsky, Y.; Rundquist, D.

    2004-12-01

    The analysis of on active faults and seismicity shows that the only a northern part of Eurasia should be regarded as an indivisible lithosphere unit. We defined it as the North Eurasian plate (Gatinsky, Rundquist, 2004) unlike the Eurasian plate s.l., which can be used only for paleotectonic reconstructions. The North Eurasian plate is bordered by zones of seismic activity traced along the Gakkel ridge, the Chersky and Stanovoi ranges, the Baikal rift, Altai--Sayany region, northern Tien Shan, Pamir, Hindu Kush and Kopet Dagh, Great Caucasus, northern Anatolia, Rhodopes, Carpathians, eastern and central Alps. Relationships between this plate and Europe west of the Rhine grabens remain ambiguous. The satellite measurements for them seem to be similar (Nocquet, Calais, 2003), but structural and seismic evidences allow suggesting their incipient division. Wide zones between this plate and neighboring ones can be distinguished outside north Eurasia. These zones consist of numerous blocks of various sizes. Block boundaries are mainly characterized by the high seismicity and development of active wrench faults, thrusts or modern rifts. Some of such zones were named earlier as "diffuse plate boundaries" (Stein et al., 2002; Bird et al, 2003). We suggest to name them as "transit zones" because they are situated between large lithosphere plates and as if transfer the stress field of one of them to other. Blocks within the transit zones reveal local divergences in GPS vectors of their displacements in the ITRF system and especially with respect to fixed Eurasia. At the same time data of satellite measurements emphasize the unity of the North Eurasian plate, which moves eastward in absolute coordinates with some clockwise rotation. The stress distribution in inner parts of the continent is being affected by the interaction with different plates and blocks. It can be more effectively illustrated by a «triangle» of the maximal seismic activity of Eurasia in the central Asia

  11. Thermal Field Indicator for Identifying Active Faults and its Instability From Laboratory Experiments

    NASA Astrophysics Data System (ADS)

    Ma, J.; Liu, L.; Liu, P.; Ma, S.

    2007-12-01

    The relationship between the thermal filed and strain field during deformation of faults is the physical basis to clarify whether satellite infrared information and the ground temperature field can be used to study fault activity. This study attempts to discuss these problems by experiments in the laboratory. The two-direction servo-control system was used to load on the samples with compressional and extensional en echelon faults. An infrared thermal image system and a contact-type thermometer recorded synchronously variations of the bright temperature field of infrared radiation and temperature field during deformation of the rock specimens. A digital CCD camera and a soft ware based on the digital speckle correlation method (DSCM) was utilized to capture images and to analyze them, yielding processes of displacement and strain fields. The experimental result shows as follows: 1 The temperature is highest at the jog area of the compressional en echelon faults, whereas that is lowest at the extensional en echelon faults prior to failure of the jog area. The record by DSCM displays that the mean strain of the jog area is largest for the compressional en echelon faults, while that is smallest for the extensional en echelon faults. These mean that the temperature field has clear responses to the opposite stress states at the jog areas of two kinds of en echelon faults, providing an indicator for determining whether the fault segment has slid. 2 The en echelon faults experience two deformation stages from stress building up and fault propagating at the jog area to unstable sliding along the fault. Correspondingly the mechanism of heating-up is turned from strain heating into frictional heating. Three kinds of phenomena have been observed at the jog area and its vicinity during the stage of transformation. They are temperature drop, fast fluctuation of temperature, and pulses of temperature rising, respectively. Mechanism of these phenomena is discussed. 3 These

  12. Upper Pleistocene - Holocene activity of the Carrascoy Fault (Murcia, SE Spain): preliminary results from paleoseismological research.

    NASA Astrophysics Data System (ADS)

    Martin-Banda, Raquel; Garcia-Mayordomo, Julian; Insua-Arevalo, Juan M.; Salazar, Angel; Rodriguez-Escudero, Emilio; Alvarez-Gomez, Jose A.; Martinez-Diaz, Jose J.; Herrero, Maria J.; Medialdea, Alicia

    2014-05-01

    The Carrascoy Fault is located in the Internal Zones of the Betic Cordillera (Southern Spain). In particular, the Carrascoy Fault is one of the major faults forming the Eastern Betic Shear Zone, the main structure accommodating the convergence between Nubian and Eurasian plates in the westernmost Mediterranean. So far, the Carrascoy Fault has been defined as a left-lateral strike-slip fault. It extends for at least 31 km in a NE-SW trend from the village of Zeneta (Murcia) at its northeastern tip, to the Cañaricos village, controlling the northern edge of the Carrascoy Range and its linkage to the Guadalentin Depression towards the southwest. This is an area of moderate seismic activity, but densely populated, the capital of the region, Murcia, being settled very close to the fault. Hence, the knowledge of the structure and kinematics of the Carrascoy Fault is essential for assessing reliably the seismic hazard of the region. We present a detailed-scale geological and geomorphological map along the fault zone created from a LIDAR DEM combined with fieldwork, and geological and geophysical information. Furthermore, a number of trenches have been dug across the fault at different locations providing insights in the fault most recent activity as well as paleoseismic data. Preliminary results suggest that the Cararscoy Fault has recently changed its kinematic showing a near pure reverse motion. According to this, the fault can be divided into two distinct segments, the eastern one: Zeneta - Fuensanta, and the western one: Fuensanta - Cañaricos, each one having its own characteristic style and geodynamics. Some new active strands of the fault locate at the foot of the very first relief towards the North of the older strand, forming the current southern border of the Guadalentin Depression. These new faults show an increasingly reverse component westwards, so that the Fuensanta - Cañaricos segment is constituted by thrusts, which are blind at its western end

  13. A pilot GIS database of active faults of Mt. Etna (Sicily): A tool for integrated hazard evaluation

    NASA Astrophysics Data System (ADS)

    Barreca, Giovanni; Bonforte, Alessandro; Neri, Marco

    2013-02-01

    A pilot GIS-based system has been implemented for the assessment and analysis of hazard related to active faults affecting the eastern and southern flanks of Mt. Etna. The system structure was developed in ArcGis® environment and consists of different thematic datasets that include spatially-referenced arc-features and associated database. Arc-type features, georeferenced into WGS84 Ellipsoid UTM zone 33 Projection, represent the five main fault systems that develop in the analysed region. The backbone of the GIS-based system is constituted by the large amount of information which was collected from the literature and then stored and properly geocoded in a digital database. This consists of thirty five alpha-numeric fields which include all fault parameters available from literature such us location, kinematics, landform, slip rate, etc. Although the system has been implemented according to the most common procedures used by GIS developer, the architecture and content of the database represent a pilot backbone for digital storing of fault parameters, providing a powerful tool in modelling hazard related to the active tectonics of Mt. Etna. The database collects, organises and shares all scientific currently available information about the active faults of the volcano. Furthermore, thanks to the strong effort spent on defining the fields of the database, the structure proposed in this paper is open to the collection of further data coming from future improvements in the knowledge of the fault systems. By layering additional user-specific geographic information and managing the proposed database (topological querying) a great diversity of hazard and vulnerability maps can be produced by the user. This is a proposal of a backbone for a comprehensive geographical database of fault systems, universally applicable to other sites.

  14. Evidence for propagating, active tensional faulting in Upper Kåfjord valley, Troms County, Norway

    NASA Astrophysics Data System (ADS)

    Redfield, T. F.; Osmundsen, P. T.; Henderson, I. H. C.; Hermanns, R. L.

    2010-05-01

    New concepts governing margin extension and post-rift passive margin evolution are appearing from onshore and offshore studies. In Norway topographic escarpments, creation, preservation and destruction of landforms, and drainage patterns are related to structural templates created during the Jurassic rift phase. Contradicting the notion that post-rift isostatic compensation, thermal subsidence, and topographic degradation mark a passive margin's final evolutionary phases, we present geological evidence for currently-active tensional deformation, accommodated by release faulting, in uppermost Kåfjordalen and Signaldalen. In Signaldalen, propagation of the deformation tip has introduced active normal faulting to Finland. Ground observations indicate a large normal fault defines the eastern border of the Lyngen 'Alps' peninsula. There, a series of exceptionally well-preserved triangular facets adorn a sharp, elevated escarpment. To the east a swarm of small NE-trending normal faults are exposed in roadside outcrops near the mouth of Kåfjord, dipping both to the NW and SE. Displacement across the fault swarm is asymmetric, the greatest component of motion being down-to-the-NW in the direction of the Lyngen Fault. Another set of NE trending, NW dipping faults crop out at Revsdalfjellet. We interpret these faults to reflect splays to the Lyngen Fault. The hanging wall of the Lyngen Fault is characterized by numerous clusters of fault-controlled rockslides. We interpret the valleys of Signaldalen, Skibotndalen, and Kåfjordalen, located in the hanging wall of the Lyngen Fault, to have formed at least partly under the influence of release faults that accommodated hanging wall flexure and failure. Other fault scarps, trending more NW-SE, crop out at two Kåfjord rockslide sites, Nomandalstinden and Litledalen. Mineralized surfaces exhibiting dip-slip slickenlines indicate most of these faults are true tectonic features, not simply gravitationally-driven 'sackung' planes

  15. Newly identified active faults in the Pollino seismic gap, southern Italy, and their seismotectonic significance

    NASA Astrophysics Data System (ADS)

    Brozzetti, Francesco; Cirillo, Daniele; de Nardis, Rita; Cardinali, Mauro; Lavecchia, Giusy; Orecchio, Barbara; Presti, Debora; Totaro, Cristina

    2017-01-01

    The following is a geological study of a Quaternary and active normal fault-system, which crops out in the Pollino area, a seismogenic sector of the Southern Apennines, Italy. From 2010 to 2014, this area was affected by long lasting seismic activity characterized by three major events which occurred in May 2012 (Mw 4.3), in October 2012 (Mw 5.2) and in June 2014 (Mw 4.0). The integration of structural-geological data with morpho-structural and remote sensing analyses, led to define the geometry, the kinematics, the cross-cutting relationships and the slip rates of the inferred active fault segments within and near the epicentral area. We reconstructed an asymmetric extensional pattern characterized by low-angle, E and NNE-dipping faults, and by antithetic, high-angle, SW- to WSW-dipping faults. The geometry of the faults at depth was constrained using high-resolution hypocenter distributions. The overall system fits well with the deformation field obtained from focal mechanisms and geodetic data. Comparing the fault pattern with the time-space evolution of the Pollino seismic activity, we identified the seismogenic sources in two, near-parallel, WSW-dipping faults, whose seismogenic potential were assessed. The peculiar perpendicular-to-fault-strike evolution of the seismic activity, is discussed in the frame of the reconstructed seismotectonic model.

  16. Digital Database of Recently Active Traces of the Hayward Fault, California

    USGS Publications Warehouse

    Lienkaemper, James J.

    2006-01-01

    The purpose of this map is to show the location of and evidence for recent movement on active fault traces within the Hayward Fault Zone, California. The mapped traces represent the integration of the following three different types of data: (1) geomorphic expression, (2) creep (aseismic fault slip),and (3) trench exposures. This publication is a major revision of an earlier map (Lienkaemper, 1992), which both brings up to date the evidence for faulting and makes it available formatted both as a digital database for use within a geographic information system (GIS) and for broader public access interactively using widely available viewing software. The pamphlet describes in detail the types of scientific observations used to make the map, gives references pertaining to the fault and the evidence of faulting, and provides guidance for use of and limitations of the map. [Last revised Nov. 2008, a minor update for 2007 LiDAR and recent trench investigations; see version history below.

  17. Determination of paleoseismic activity over a large time-scale: Fault scarp dating with 36Cl

    NASA Astrophysics Data System (ADS)

    Mozafari Amiri, Nasim; Tikhomirov, Dmitry; Sümer, Ökmen; Özkaymak, Çaǧlar; Uzel, Bora; Ivy-Ochs, Susan; Vockenhuber, Christof; Sözbilir, Hasan; Akçar, Naki

    2016-04-01

    Bedrock fault scarps are the most direct evidence of past earthquakes to reconstruct seismic activity in a large time-scale using cosmogenic 36Cl dating if built in carbonates. For this method, a surface along the fault scarp with a minimum amount of erosion is required to be chosen as an ideal target point. The section of the fault selected for sampling should cover at least two meters of the fault surface from the lower part of the scarp, where intersects with colluvium wedge. Ideally, sampling should be performed on a continuous strip along the direction of the fault slip direction. First, samples of 10 cm high and 15 cm wide are marked on the fault surface. Then, they are collected using cutters, hammer and chisel in a thickness of 3 cm. The main geometrical factors of scarp dip, scarp height, top surface dip and colluvium dip are also measured. Topographic shielding in the sampling spot is important to be estimated as well. Moreover, density of the fault scarp and colluvium are calculated. The physical and chemical preparations are carried in laboratory for AMS and chemical analysis of the samples. A Matlab® code is used for modelling of seismically active periods based on increasing production rate of 36Cl following each rupture, when a buried section of a fault is exposed. Therefore, by measuring the amount of cosmogenic 36Cl versus height, the timing of major ruptures and their offsets are determined. In our study, Manastır, Mugırtepe and Rahmiye faults in Gediz graben, Priene-Sazlı, Kalafat and Yavansu faults in Büyük Menderes graben and Ören fault in Gökava half-graben have been examined in the seismically active region of Western Turkey. Our results reconstruct at least five periods of high seismic activity during the Holocene time, three of which reveal seismic ruptures beyond the historical pre-existing data.

  18. Recent seismogenic fault activity in a Late Quaternary closed-lake graben basin (Albacete, SE Spain)

    NASA Astrophysics Data System (ADS)

    Rodríguez-Pascua, M. A.; Pérez-López, R.; Calvo, J. P.; García del Cura, M. A.

    2008-11-01

    The Cordovilla basin, located within the frontal thrust belt of the Betic Cordillera, SE Spain, is an elongated NW-SE graben showing discrete surface rupture generated by Holocene paleoearthquake activity. A main and an antithetic normal, NW-SE trending, active faults bound the basin. Paleoseismological evidence is reported on upslope-facing scarps of the antithetic fault, acting as dams to runoff, which contributed to temporary lacustrine conditions, as well as sediment uplift. The fluvial network in the area shows a poor drainage activity, whereas a present lake is dammed by the antithetic fault. The modern landscape is controlled by Holocene faulting, modifying the geological environment according to earthquake occurrence, from flat alluvial plains to lacustrine local basins. The application of the diffusion dating technique to unconsolidated sediments for the antithetic fault scarp indicates an age between 1 and 2 ka. Various geometric parameters have been obtained in order to reconstruct the paleoseismic history of the Cordovilla graben basin. The surface rupture and fault-offset values are associated with discrete active morpholineaments, parallel to the Pozohondo Fault. The Tobarra-Cordovilla segment (the structural boundary of the Cordovilla Basin) was generated by earthquakes with magnitudes (Mw) greater than 6.0, based on Wells and Coppersmith fault scarp relations.

  19. The southern Whidbey Island fault: An active structure in the Puget Lowland, Washington

    USGS Publications Warehouse

    Johnson, S.Y.; Potter, C.J.; Armentrout, J.M.; Miller, J.J.; Finn, C.; Weaver, C.S.

    1996-01-01

    Information from seismic-reflection profiles, outcrops, boreholes, and potential field surveys is used to interpret the structure and history of the southern Whidbey Island fault in the Puget Lowland of western Washington. This northwest-trending fault comprises a broad (as wide as 6-11 km), steep, northeast-dipping zone that includes several splays with inferred strike-slip, reverse, and thrust displacement. Transpressional deformation along the southern Whidbey Island fault is indicated by alongstrike variations in structural style and geometry, positive flower structure, local unconformities, out-of-plane displacements, and juxtaposition of correlative sedimentary units with different histories. The southern Whidbey Island fault represents a segment of a boundary between two major crustal blocks. The Cascade block to the northeast is floored by diverse assemblages of pre-Tertiary rocks; the Coast Range block to the southwest is floored by lower Eocene marine basaltic rocks of the Crescent Formation. The fault probably originated during the early Eocene as a dextral strike-slip fault along the eastern side of a continental-margin rift. Bending of the fault and transpressional deformation began during the late middle Eocene and continues to the present. Oblique convergence and clockwise rotation along the continental margin are the inferred driving forces for ongoing deformation. Evidence for Quaternary movement on the southern Whidbey Island fault includes (1) offset and disrupted upper Quaternary strata imaged on seismic-reflection profiles; (2) borehole data that suggests as much as 420 m of structural relief on the Tertiary-Quaternary boundary in the fault zone; (3) several meters of displacement along exposed faults in upper Quaternary sediments; (4) late Quaternary folds with limb dips of as much as ???9??; (5) large-scale liquefaction features in upper Quaternary sediments within the fault zone; and (6) minor historical seismicity. The southern Whidbey

  20. Active fault systems of the Kivu rift and Virunga volcanic province, and implications for geohazards

    NASA Astrophysics Data System (ADS)

    Zal, H. J.; Ebinger, C. J.; Wood, D. J.; Scholz, C. A.; d'Oreye, N.; Carn, S. A.; Rutagarama, U.

    2013-12-01

    H Zal, C Ebinger, D. Wood, C. Scholz, N. d'Oreye, S. Carn, U. Rutagarama The weakly magmatic Western rift system, East Africa, is marked by fault-bounded basins filled by freshwater lakes that record tectonic and climatic signals. One of the smallest of the African Great Lakes, Lake Kivu, represents a unique geohazard owing to the warm, saline bottom waters that are saturated in methane, as well as two of the most active volcanoes in Africa that effectively dam the northern end of the lake. Yet, the dynamics of the basin system and the role of magmatism were only loosely constrained prior to new field and laboratory studies in Rwanda. In this work, we curated, merged, and analyzed historical and digital data sets, including spectral analyses of merged Shuttle Radar Topography Mission topography and high resolution CHIRP bathymetry calibrated by previously mapped fault locations along the margins and beneath the lake. We quantitatively compare these fault maps with the time-space distribution of earthquakes located using data from a temporary array along the northern sector of Lake Kivu, as well as space-based geodetic data. During 2012, seismicity rates were highest beneath Nyiragongo volcano, where a range of low frequency (1-3 s peak frequency) to tectonic earthquakes were located. Swarms of low-frequency earthquakes correspond to periods of elevated gas emissions, as detected by Ozone Monitoring Instrument (OMI). Earthquake swarms also occur beneath Karisimbi and Nyamuragira volcanoes. A migrating swarm of earthquakes in May 2012 suggests a sill intrusion at the DR Congo-Rwanda border. We delineate two fault sets: SW-NE, and sub-N-S. Excluding the volcano-tectonic earthquakes, most of the earthquakes are located along subsurface projections of steep border faults, and intrabasinal faults calibrated by seismic reflection data. Small magnitude earthquakes also occur beneath the uplifted rift flanks. Time-space variations in seismicity patterns provide a baseline

  1. Modeling of fluid injection and withdrawal induced fault activation using discrete element based hydro-mechanical and dynamic coupled simulator

    NASA Astrophysics Data System (ADS)

    Yoon, Jeoung Seok; Zang, Arno; Zimmermann, Günter; Stephansson, Ove

    2016-04-01

    Operation of fluid injection into and withdrawal from the subsurface for various purposes has been known to induce earthquakes. Such operations include hydraulic fracturing for shale gas extraction, hydraulic stimulation for Enhanced Geothermal System development and waste water disposal. Among these, several damaging earthquakes have been reported in the USA in particular in the areas of high-rate massive amount of wastewater injection [1] mostly with natural fault systems. Oil and gas production have been known to induce earthquake where pore fluid pressure decreases in some cases by several tens of Mega Pascal. One recent seismic event occurred in November 2013 near Azle, Texas where a series of earthquakes began along a mapped ancient fault system [2]. It was studied that a combination of brine production and waste water injection near the fault generated subsurface pressures sufficient to induced earthquakes on near-critically stressed faults. This numerical study aims at investigating the occurrence mechanisms of such earthquakes induced by fluid injection [3] and withdrawal by using hydro-geomechanical coupled dynamic simulator (Itasca's Particle Flow Code 2D). Generic models are setup to investigate the sensitivity of several parameters which include fault orientation, frictional properties, distance from the injection well to the fault, amount of fluid withdrawal around the injection well, to the response of the fault systems and the activation magnitude. Fault slip movement over time in relation to the diffusion of pore pressure is analyzed in detail. Moreover, correlations between the spatial distribution of pore pressure change and the locations of induced seismic events and fault slip rate are investigated. References [1] Keranen KM, Weingarten M, Albers GA, Bekins BA, Ge S, 2014. Sharp increase in central Oklahoma seismicity since 2008 induced by massive wastewater injection, Science 345, 448, DOI: 10.1126/science.1255802. [2] Hornbach MJ, DeShon HR

  2. Repeated surveys reveal nontectonic exposure of supposedly active normal faults in the central Apennines, Italy

    NASA Astrophysics Data System (ADS)

    Kastelic, Vanja; Burrato, Pierfrancesco; Carafa, Michele M. C.; Basili, Roberto

    2017-01-01

    We investigate the geomorphic processes that expose bedrock fault surfaces from under their slope-deposit cover in the central Apennines (Italy). These bedrock fault surfaces are generally located at various heights on mountain fronts above the local base level of glacio-fluvial valleys and intermountain fluvio-lacustrine basins and are laterally confined to the extent of related mountain fronts. The process that led to the exposure of fault surfaces has often been exclusively attributed to coseismic earthquake slip and used as proxy for tectonic slip rates and earthquake recurrence estimations. We present the results of monitoring the contact between the exposed fault surfaces and slope deposits at 23 measurement points on 12 different faults over 3.4 year long observation period. We detected either downward or upward movements of the slope deposit with respect to the fault surface between consecutive measurements. During the entire observation period all points, except one, registered a net downward movement in the 2.9-25.6 mm/yr range, resulting in the progressive exposure of the fault surface. During the monitoring period no major earthquakes occurred in the region, demonstrating that the measured exposure process is disconnected from seismic activity. Our results indicate that the fault surface exposure rates are rather due to gravitational and landsliding movements aided by weathering and slope degradation processes. The so far neglected slope degradation and other (sub)surface processes should thus be carefully taken into consideration before attempting to recover fault slip rates using surface gathered data.

  3. Active fault, fault growth and segment linkage along the Janauri anticline (frontal foreland fold), NW Himalaya, India

    NASA Astrophysics Data System (ADS)

    Malik, Javed N.; Shah, Afroz A.; Sahoo, Ajit K.; Puhan, B.; Banerjee, Chiranjib; Shinde, Dattatraya P.; Juyal, Navin; Singhvi, Ashok K.; Rath, Shishir K.

    2010-03-01

    The 100 km long frontal foreland fold — the Janauri anticline in NW Himalayan foothills represents a single segment formed due to inter-linking of the southern (JS1) and the northern (JS2) Janauri segments. This anticline is a product of the fault related fold growth that facilitated lateral propagation by acquiring more length and linkage of smaller segments giving rise to a single large segment. The linked portion marked by flat-uplifted surface in the central portion represents the paleo-water gap of the Sutlej River. This area is comparatively more active in terms of tectonic activity, well justified by the occurrence of fault scarps along the forelimb and backlimb of the anticline. Occurrence of active fault scarps on either side of the anticline suggests that the slip accommodated in the frontal part is partitioned between the main frontal thrust i.e. the Himalayan Frontal Thrust (HFT) and associated back-thrust. The uplift in the piedmont zone along southern portion of Janauri anticline marked by dissected younger hill range suggests fore-landward propagation of tectonic activity along newly developed Frontal Piedmont Thrust (FPT), an imbricated emergent thrust branching out from the HFT system. We suggests that this happened because the southern segment JS1 does not linked-up with the northwestern end of Chandigarh anticline segment (CS). In the northwestern end of the Janauri anticline, due to no structural asperity the tectonic activity on HFT was taken-up by two (HF1 — in the frontal part and HF2 — towards the hinterland side) newly developed parallel active faults ( Hajipur Fault) branched from the main JS2 segment. The lateral propagation and movements along HF1 and HF2 resulted in uplift of the floodplain as well as responsible for the northward shift of the Beas River. GPR and trench investigations suggest that earthquakes during the recent past were accompanied with surface rupture. OSL (optical stimulated luminescence) dates from the trench

  4. Modelling Active Faults in Probabilistic Seismic Hazard Analysis (PSHA) with OpenQuake: Definition, Design and Experience

    NASA Astrophysics Data System (ADS)

    Weatherill, Graeme; Garcia, Julio; Poggi, Valerio; Chen, Yen-Shin; Pagani, Marco

    2016-04-01

    The Global Earthquake Model (GEM) has, since its inception in 2009, made many contributions to the practice of seismic hazard modeling in different regions of the globe. The OpenQuake-engine (hereafter referred to simply as OpenQuake), GEM's open-source software for calculation of earthquake hazard and risk, has found application in many countries, spanning a diversity of tectonic environments. GEM itself has produced a database of national and regional seismic hazard models, harmonizing into OpenQuake's own definition the varied seismogenic sources found therein. The characterization of active faults in probabilistic seismic hazard analysis (PSHA) is at the centre of this process, motivating many of the developments in OpenQuake and presenting hazard modellers with the challenge of reconciling seismological, geological and geodetic information for the different regions of the world. Faced with these challenges, and from the experience gained in the process of harmonizing existing models of seismic hazard, four critical issues are addressed. The challenge GEM has faced in the development of software is how to define a representation of an active fault (both in terms of geometry and earthquake behaviour) that is sufficiently flexible to adapt to different tectonic conditions and levels of data completeness. By exploring the different fault typologies supported by OpenQuake we illustrate how seismic hazard calculations can, and do, take into account complexities such as geometrical irregularity of faults in the prediction of ground motion, highlighting some of the potential pitfalls and inconsistencies that can arise. This exploration leads to the second main challenge in active fault modeling, what elements of the fault source model impact most upon the hazard at a site, and when does this matter? Through a series of sensitivity studies we show how different configurations of fault geometry, and the corresponding characterisation of near-fault phenomena (including

  5. Geomorphic features of active faults around the Kathmandu Valley, Nepal, and no evidence of surface rupture associated with the 2015 Gorkha earthquake along the faults

    NASA Astrophysics Data System (ADS)

    Kumahara, Yasuhiro; Chamlagain, Deepak; Upreti, Bishal Nath

    2016-04-01

    The M7.8 April 25, 2015, Gorkha earthquake in Nepal was produced by a slip on the low-angle Main Himalayan Thrust, a décollement below the Himalaya that emerges at the surface in the south as the Himalayan Frontal Thrust (HFT). The analysis of the SAR interferograms led to the interpretations that the event was a blind thrust and did not produce surface ruptures associated with the seismogenic fault. We conducted a quick field survey along four active faults near the epicentral area around the Kathmandu Valley (the Jhiku Khola fault, Chitlang fault, Kulekhani fault, Malagiri fault and Kolphu Khola fault) from July 18-22, 2015. Those faults are located in the Lesser Himalaya on the hanging side of the HFT. Based on our field survey carried out in the area where most typical tectonic landforms are developed, we confirmed with local inhabitants the lack of any new surface ruptures along these faults. Our observations along the Jhiku Khola fault showed that the fault had some definite activities during the Holocene times. Though in the past it was recognized as a low-activity thrust fault, our present survey has revealed that it has been active with a predominantly right-lateral strike-slip with thrust component. A stream dissecting a talus surface shows approximately 7-m right-lateral offset, and a charcoal sample collected from the upper part of the talus deposit yielded an age of 870 ± 30 y.B.P, implying that the talus surface formed close to 870 y.B.P. Accordingly, a single or multiple events of the fault must have occurred during the last 900 years, and the slip rate we estimate roughly is around 8 mm/year. The fault may play a role to recent right-lateral strike-slip tectonic zone across the Himalayan range. Since none of the above faults showed any relationship corresponding to the April 25 Gorkha earthquake, it is possibility that a potential risk of occurrence of large earthquakes does exist close to the Kathmandu Valley due to movements of these active

  6. Active fault systems and tectono-topographic configuration of the central Trans-Mexican Volcanic Belt

    NASA Astrophysics Data System (ADS)

    Szynkaruk, Ewa; Graduño-Monroy, Víctor Hugo; Bocco, Gerardo

    2004-07-01

    The central Trans-Mexican Volcanic Belt (TMVB) reflects the interplay between three regional fault systems: the NNW-SSE to NW-SE striking Taxco-Querétaro fault system, the NE-SW striking system, and the E-W striking Morelia-Acambay fault system. The latter is the youngest and consists of fault scarps up to 500 m high, whose formation caused structural and morphological reorganization of the region. In this paper, we investigate possible activity of the three systems within the central TMVB, and assess the role that they play in controlling the tectono-topographic configuration of the area. Our study is based on DEM-derived morphometric maps, longitudinal river profiles, geomorphologic mapping, and structural field data concerning recent faulting. We find that all three regional fault systems are active within the central TMVB, possibly with different displacement rates and/or type of motion; and that NNW-SSE and NE-SW striking faults control the major tectono-topographic elements that build up the region, which are being re-shaped by E-W striking faults. We also find that tectonic information can be deciphered from the topography of the youthful volcanic arc in question, regardless its complexity.

  7. Lithospheric Control on Spatial Patterns of Active Faulting in the Southeastern Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Amos, C. B.; Unruh, J. R.; Lutz, A.; Fisher, B.; Kelson, K. I.; Rood, D. H.; Jayko, A. S.

    2011-12-01

    Patterns of active faulting in the southeastern Sierra Nevada of California reflect both far-field plate motion as well as localized forces that drive seismogenic deformation. Oblique divergence between the Sierra and the western Cordillera results in an overall pattern of dextral shear and northwest-directed extension in the eastern California shear zone (ECSZ) and southern Walker Lane belt. Within the nominally rigid southern Sierra Nevada block, newly recognized active normal faulting, as well as seismicity, indicate primarily extensional deformation beneath the high topography of the southern range. Investigations of the northern Kern Canyon fault, the Little Lake fault, and the Sierra Nevada range-front faults in Rose Valley combine data from both aerial and ground-based laser scanning, paleoseismic trenching, geologic and geomorphic mapping, and surface exposure dating to define spatial and temporal patterns of fault slip. Taken together, these studies indicate that deformation kinematics along the southeastern Sierran escarpment undergo a pronounced shift at an approximate latitude of 36.5° N. To the north in Owens valley, range-front faults accommodate active extension and normal faulting, while the adjacent Owens Valley fault displays primarily dextral strike-slip motion. South of Lone Pine, however, a component of active normal faulting steps westward into the southern Sierra Nevada block to the Kern Canyon fault, while range-front faults in Rose Valley accommodate a significant component of oblique dextral extension. Focal mechanism inversion of earthquakes in the southern Sierra Nevada reveals a zone of horizontal extension and vertical crustal thinning coincident with this westward shift of normal faulting into the range. The zone of extension is directly east of the "Isabella Anomaly," a zone of anomalous high P-wave mantle velocities thought to reflect convectively downwelling or foundering lower Sierran lithosphere below the Central Valley. As such

  8. The offshore Yangsan fault activity in the Quaternary, SE Korea: Analysis of high-resolution seismic profiles

    NASA Astrophysics Data System (ADS)

    Kim, Han-Joon; Moon, Seonghoon; Jou, Hyeong-Tae; Lee, Gwang Hoon; Yoo, Dong Geun; Lee, Sang Hoon; Kim, Kwang Hee

    2016-12-01

    The NNE-trending dextral Yangsan fault is a > 190-km-long structure in the Korean Peninsula traced to the southeastern coast. The scarcity of Quaternary deposits onland precludes any detailed investigation of the Quaternary activity and structure of the Yangsan fault using seismic reflection profiling. We acquired offshore high-resolution seismic profiles to investigate the extension of the Yangsan fault and constrain its Quaternary activity using stratigraphic markers. The seismic profiles reveal a NNE-trending fault system consisting of a main fault and an array of subsidiary faults that displaced Quaternary sequences. Stratigraphic analysis of seismic profiles indicates that the offshore faults were activated repeatedly in the Quaternary. The up-to-the-east sense of throw on the main fault and plan-view pattern of the fault system are explained by dextral strike-slip faulting. The main fault, when projected toward the Korean Peninsula along its strike, aligns well with the Yangsan fault. We suggest that the offshore fault system is a continuation of the Yangsan fault and has spatial correlation with weak but ongoing seismicity.

  9. Distribution of fault activity in the early stages of continental breakup: an analysis of faults and volcanic products of the Natron Basin, East African Rift, Tanzania

    NASA Astrophysics Data System (ADS)

    Muirhead, J. D.; Kattenhorn, S. A.

    2012-12-01

    Recent magmatic-tectonic crises in Ethiopia (e.g. 2005 Dabbahu rifting episode, Afar) have informed our understanding of the spatial and temporal distribution of strain in magmatic rifts transitioning to sea-floor spreading. However, the evolving contributions of magmatic and tectonic processes during the initial stages of rifting, is a subject of ongoing debate. The <5 Ma northern Tanzania and southern Kenya sectors of the East Africa Rift provide ideal locations to address this problem. We present preliminary findings from an investigation of fault structures utilizing aerial photography and satellite imagery of the ~35 km wide Natron rift-basin in northern Tanzania. Broad-scale structural mapping will be supplemented by field observations and 40Ar-39Ar dating of lava flows cut by faults to address three major aspects of magma-assisted rifting: (1) the relative timing of activity between the border fault and smaller faults distributed across the width of the rift; (2) time-averaged slip rates along rift-zone faults; and (3) the spatial distribution of faults and volcanic products, and their relative contributions to strain accommodation. Preliminary field observations suggest that the ~500 m high border fault system along the western edge of the Natron basin is either inactive or has experienced a reduced slip rate and higher recurrence interval between surface-breaking events, as evidence by a lack of recent surface-rupture along the main fault escarpments. An exception is an isolated, ~2 km-long segment of the Natron border fault, which is located in close proximity (< 5km) to the active Oldoinyo Lengai volcano. Here, ~10 m of seemingly recent throw is observed in volcaniclastic deposits. The proximity of the fault segment to Oldoinyo Lengai volcano and the localized distribution of fault-slip are consistent with magma-assisted faulting. Faults observed within the Natron basin and on the flanks of Gelai volcano, located on the eastern side of the rift, have

  10. Observations of Seafloor Deformation and Methane Venting within an Active Fault Zone Offshore Southern California

    NASA Astrophysics Data System (ADS)

    Anderson, K.; Lundsten, E. M.; Paull, C. K.; Caress, D. W.; Thomas, H. J.; Brewer, P. G.; Vrijenhoek, R.; Lundsten, L.

    2013-12-01

    Detailed mapping surveys of the floor and flanks of the Santa Monica Basin, San Pedro Basin, and San Diego Trough were conducted during the past seven years using an Autonomous Underwater Vehicle (AUV) built and operated by MBARI specifically for seafloor mapping. The AUV collected data provide up to 1 m resolution multibeam bathymetric grids with a vertical precision of 0.15 m. Along with high-resolution multibeam, the AUV also collects chirp seismic reflection profiles. Structures within the uppermost 10-20 m of the seafloor, which in the surveys presented here is composed of recent sediment drape, can typically be resolved in the sub-bottom reflectors. Remotely operated vehicle (ROV) dives allowed for ground-truth observations and sampling within the surveyed areas. The objectives of these dives included finding evidence of recent seafloor deformation and locating areas where chemosynthetic biological communities are supported by fluid venting. Distinctive seafloor features within an active fault zone are revealed in unprecedented detail in the AUV generated maps and seismic reflection profiles. Evidence for recent fault displacements include linear scarps which can be as small as 20 cm high but traceable for several km, right lateral offsets within submarine channels and topographic ridges, and abrupt discontinuities in sub-bottom reflectors, which in places appear to displace seafloor sediments. Several topographic highs that occur within the fault zone appear to be anticlines related to step-overs in these faults. These topographic highs are, in places, topped with circular mounds that are up to 15 m high and have ~30° sloping sides. The crests of the topographic highs and the mounds both have distinctive rough morphologies produced by broken pavements of irregular blocks of methane-derived authigenic carbonates, and by topographic depressions, commonly more than 2 m deep. These areas of distinctive rough topography are commonly associated with living

  11. Assessing the activity of faults in continental interiors: Palaeoseismic insights from SE Kazakhstan

    NASA Astrophysics Data System (ADS)

    Grützner, C.; Carson, E.; Walker, R. T.; Rhodes, E. J.; Mukambayev, A.; Mackenzie, D.; Elliott, J. R.; Campbell, G.; Abdrakhmatov, K.

    2017-02-01

    The presence of fault scarps is a first-order criterion for identifying active faults. Yet the preservation of these features depends on the recurrence interval between surface rupturing events, combined with the rates of erosional and depositional processes that act on the landscape. Within arid continental interiors single earthquake scarps can be preserved for thousands of years, and yet the interval between surface ruptures on faults in these regions may be much longer, such that the lack of evidence for surface faulting in the morphology may not preclude activity on those faults. In this study we investigate the 50 km-long 'Toraigyr' thrust fault in the northern Tien Shan. From palaeoseismological trenching we show that two surface rupturing earthquakes occurred in the last 39.9 ± 2.7 ka BP, but only the most recent event (3.15-3.6 ka BP) has a clear morphological expression. We conclude that a landscape reset took place in between the two events, likely as a consequence of the climatic change at the end of the last glacial maximum. These findings illustrate that in the Tien Shan evidence for the most recent active faulting can be easily obliterated by climatic processes due to the long earthquake recurrence intervals. Our results illustrate the problems related to the assessment of active tectonic deformation and seismic hazard assessments in continental interior settings.

  12. Mapping Active Faults and Tectonic Geomorphology offshore central California

    NASA Astrophysics Data System (ADS)

    Johnson, S. Y.; Watt, J. T.; Hart, P. E.; Sliter, R. W.; Wong, F. L.

    2009-12-01

    In June 2008, and July 2009, the USGS conducted two high-resolution, marine, seismic-reflection surveys across the continental shelf and upper slope between Piedras Blancas and Point Sal, central California, in order to better characterize regional earthquake sources. More than 1,300 km of single-channel seismic data were acquired aboard the USGS R/V Parke Snavely using a 500-joule mini-sparker source fired at a 0.5-second shot interval and recorded with a 15-meter streamer. Most tracklines were run perpendicular to the coast at 800-meter spacing, extending from the nearshore (~ 10-15 m water depth) to as far as 20 km offshore. Sub-bottom imaging varies with substrate, ranging from outstanding (100 to 150 m of penetration) in inferred Quaternary shallow marine, shelf and upper slope deposits to poor (0 to 10 m) in the Mesozoic basement rocks. Marine magnetic data were collected simultaneously on this survey, and both data sets are being integrated with new aeromagnetic data, publicly available industry seismic-reflection data, onshore geology, seismicity, and high-resolution bathymetry. Goals of the study are to map geology, structure, and sediment distribution; to document fault location, length, segmentation, shallow geometry and structure; and to identify possible sampling targets for constraining fault slip rates, earthquake recurrence, and tsunami hazard potential. The structure and tectonic geomorphology of the >100-km-long, right-lateral, Hosgri fault zone and its connections to the Los Osos, Pecho, Oceano and other northwest-trending inboard faults are the focus of this ongoing work. The Hosgri fault forms the eastern margin of the offshore Santa Maria basin and coincides in places with the outer edge of the narrow (5- to 15-km-wide), structurally complex continental shelf. The Hosgri is imaged as a relatively continuous, vertical fault zone that extends upward to the seafloor; varies significantly and rapidly along strike; and incorporates numerous

  13. Pluton pinning of an active Miocene detachment fault system, eastern Mojave Desert, California

    NASA Astrophysics Data System (ADS)

    Davis, Gregory A.; Fowler, T. Kenneth; Bishop, Kim M.; Brudos, Thomas C.; Julio Friedmann, S.; Burbank, Douglas W.; Parke, Mary A.; Burchfiel, B. C.

    1993-07-01

    The Miocene Kingston Range-Halloran Hills detachment fault system of the eastern Mojave Desert, California, delineates part of the eastern breakaway zone for a profoundly extended area between the Sierra Nevada and the Spring Mountains structural blocks. The shallow-dipping, west-rooting detachment fault cuts discordantly across Paleozoic and Precambrian units in the Mesozoic foreland fold-and-thrust belt, exhibits west- to southwest-trending corrugations with structural relief of up to 1.5 km, and underlies the terrestrial Shadow Valley basin. Middle Miocene fault displacement and syntectonic sedimentation in the northern basin were terminated at ˜12.4 Ma by intrusion of the large (˜130 km2), shallow-level (≥4 km depth) Kingston Peak pluton across the detachment fault soon after faulting began. Basin sedimentation and fault displacement southeast of the pluton were not, however, disrupted by its emplacement and continued to evolve. Northern "pluton-pinned" and southern "pluton-free" domains were separated by the Blacksmith Hills fault, a northeast-striking, right-slip lateral ramp that accommodated more than 3 km of postpluton differential extension between pinned and nonpinned domains. In more western regions, late phases of detachment-fault-related extension beneath formerly pinned areas (including western and central parts of the pluton itself) are believed to have led to the development of two generations of east-striking left-slip faults. Collectively, these dextral and sinistral transfer faults illustrate the complex patterns of differential extension and accommodation that can characterize detachment-fault systems as adjacent areal domains of extension are generated and die.

  14. An update of Quaternary faults of central and eastern Oregon

    USGS Publications Warehouse

    Weldon, Ray J.; Fletcher, D.K.; Weldon, E.M.; Scharer, K.M.; McCrory, P.A.

    2002-01-01

    This is the online version of a CD-ROM publication. We have updated the eastern portion of our previous active fault map of Oregon (Pezzopane, Nakata, and Weldon, 1992) as a contribution to the larger USGS effort to produce digital maps of active faults in the Pacific Northwest region. The 1992 fault map has seen wide distribution and has been reproduced in essentially all subsequent compilations of active faults of Oregon. The new map provides a substantial update of known active or suspected active faults east of the Cascades. Improvements in the new map include (1) many newly recognized active faults, (2) a linked ArcInfo map and reference database, (3) more precise locations for previously recognized faults on shaded relief quadrangles generated from USGS 30-m digital elevations models (DEM), (4) more uniform coverage resulting in more consistent grouping of the ages of active faults, and (5) a new category of 'possibly' active faults that share characteristics with known active faults, but have not been studied adequately to assess their activity. The distribution of active faults has not changed substantially from the original Pezzopane, Nakata and Weldon map. Most faults occur in the south-central Basin and Range tectonic province that is located in the backarc portion of the Cascadia subduction margin. These faults occur in zones consisting of numerous short faults with similar rates, ages, and styles of movement. Many active faults strongly correlate with the most active volcanic centers of Oregon, including Newberry Craters and Crater Lake.

  15. Recent high-resolution seismic reflection studies of active faults in the Puget Lowland

    NASA Astrophysics Data System (ADS)

    Liberty, L. M.; Pratt, T. L.

    2005-12-01

    In the past four years, new high-resolution seismic surveys have filled in key gaps in our understanding of active structures beneath the Puget Lowland, western Washington State. Although extensive regional and high-resolution marine seismic surveys have been fundamental to understanding the tectonic framework of the area, these marine profiles lack coverage on land and in shallow or restricted waterways. The recent high-resolution seismic surveys have targeted key structures beneath water bodies that large ships cannot navigate, and beneath city streets underlain by late Pleistocene glacial deposits that are missing from the waterways. The surveys can therefore bridge the gap between paleoseismic and marine geophysical studies, and test key elements of models proposed by regional-scale geophysical studies. Results from these surveys have: 1) documented several meters of vertical displacement on at least two separate faults in the Olympia area; 2) clarified the relationship between the Catfish Lake scarp and the underlying kink band in the Tacoma fault zone; 3) provided a first look at the structures beneath the north portion of the western Tacoma fault zone, north of previous marine profiles; 4) documented that deformation along the Seattle fault extends well east of Lake Sammamish; 5) imaged the Seattle fault beneath the Vasa Park trench; and 6) documented multiple fault strands in and south of the Seattle fault zone south of Bellevue. The results better constrain interpretations of paleoseismic investigations of past earthquakes on these faults, and provide targets for future paleoseismic studies.

  16. Extensive Submarine Active Fault and the 2011 off the Pacific Coast of Tohoku Earthquake

    NASA Astrophysics Data System (ADS)

    Nakata, T.; Kumamoto, T.; Muroi, S.; Watanabe, M.

    2013-12-01

    Active faults observed on seafloor along Japan Trench are resultants of repeated large earthquakes. We discuss on the relation between large earthquakes and their source faults based on a detailed active fault map along Japan Trench. Judging from location and continuation of active faults in the earthquake source area, we consider that one of the extensive thrust faults which extends from off-Sanriku to off-Ibaraki for about 500km, is directly related to the source fault of the 2011 off the Pacific coast of Tohoku Earthquake. The 2011 off the Pacific Coast of Tohoku Earthquake (Mw9.0) generated large tsunami with massive pulsating pattern of waves (Maeda et al. 2011). A leading hypothesis believed among many seismologists that an earthquake source fault that generated the earthquake, caused the near-surface fault rupture along the axis of Japan Trench, and large displacement ~50m eastward and ~7 to ~10m upward was estimated from comparison of data obtained before and after the earthquake in 2004 and 2011 by multibeam bathymetric surveys across the trench (Fujiwara et al. 2011). Satake et al. (2011) explained the large tsunami height by simultaneous faulting on two different fault planes, one on subducting plate boundary and the other near the trench axis. Since most of the workers hypothesized without any doubt believed that the earthquake was caused by the fault ruptured up to the trench axis, existence of submarine active fault is rather overlooked so far. However, we consider the large displacement is due to landslide and do not find any extensive fault scarp on the trench axis. We simulated pattern of seafloor deformation associated with the earthquake using a simple dislocation model for a single fault plane with uniform slip that dips 14 degree in depth and 33.6 degree beneath the tectonic bulge related to the extensive active fault. A result shows that an area of large uplift agrees more or less with the location of tectonic bulge with width of about 20km

  17. Assessing fault activity in intracontinental settings: paleoseismology and geomorphology in SE Kazakhstan

    NASA Astrophysics Data System (ADS)

    Grützner, Christoph; Carson, Emily; Mackenzie, David; Elliott, Austin; Campbell, Grace; Walker, Richard; Abdrakhmatov, Kanatbek

    2016-04-01

    Earthquake recurrence intervals of active faults often exceed the time span covered by instrumental, historical, and archaeological earthquake records in continental interiors. The identification of active faults then often relies on finding the geomorphological expression of surface faulting preserved in the landscape. In rather arid areas, single earthquake scarps can be preserved for thousands of years, but erosional and depositional processes will eventually obliterate features such as fault scarps and offset geological markers. Active faults with very long intervals between surface ruptures might therefore remain undetected, which constitutes a major problem for tectonic studies and seismic hazard assessment. Here we present data from the 50 km-long 'Charyn Canyon' thrust fault in the northern Tien Shan (SE Kazakhstan). Remote sensing, Structure-from-Motion (SfM), differential GPS, field mapping, and paleoseismic trenching were used to reveal the earthquake history of this fault. Radiocarbon dating, infra-red stimulated luminescence (IRSL), and scarp diffusion modelling were used for bracketing the occurrence of paleo-earthquakes. In the paleoseismological trenches we identified two surface rupturing events within the last ~37 ka BP. The most recent earthquake took place between 3.5 - 7.3 ka BP, the penultimate event occurred between ~17-37 ka BP. We estimate magnitudes of ~MW6.5-7.3. Only the younger event has a morphological expression as a 25 km-long fault scarp of ~2 m height. This implicates that a major landscape reset occurred between these two earthquakes, most likely related to the significant climatic change that marked the end of the last glacial maximum. Similar observations from other paleoseismic investigation sites in this area support this interpretation. Our study shows that faults in the northern Tien Shan tend to break in strong earthquakes with very long recurrence intervals. As a consequence, morphological evidence for the most recent

  18. Deformed Neogene basins, active faulting and topography in Westland: Distributed crustal mobility west of the Alpine Fault transpressive plate boundary (South Island, New Zealand)

    NASA Astrophysics Data System (ADS)

    Ghisetti, Francesca; Sibson, Richard H.; Hamling, Ian

    2016-12-01

    Tectonic activity in the South Island of New Zealand is dominated by the Alpine Fault component of the Australia-Pacific plate boundary. West of the Alpine Fault deformation is recorded by Paleogene-Neogene basins coeval with the evolution of the right-lateral/transpressive plate margin. Initial tectonic setting was controlled by N-S normal faults developed during Late Cretaceous and Eocene-early Miocene rifting. Following inception of the Alpine Fault (c. 25 Ma) reverse reactivation of the normal faults controlled tectonic segmentation that became apparent in the cover sequences at c. 22 Ma. Based on restored transects tied to stratigraphic sections, seismic lines and wells, we reconstruct the vertical mobility of the Top Basement Unconformity west of Alpine Fault. From c. 37-35 Ma to 22 Ma subsidence was controlled by extensional faulting. After 22 Ma the region was affected by differential subsidence, resulting from eastward crustal flexure towards the Alpine Fault boundary and/or components of transtension. Transition from subsidence to uplift started at c. 17 Ma within a belt of basement pop-ups, separated by subsiding basins localised in the common footwall of oppositely-dipping reverse faults. From 17 to 7-3 Ma reverse fault reactivation and uplift migrated to the WSW. Persistent reverse reactivation of the inherited faults in the present stress field is reflected by the close match between tectonic block segmentation and topography filtered at a wavelength of 25 km, i.e. at a scale comparable to crustal thickness in the region. However, topography filtered at wavelength of 75 km shows marked contrasts between the elevated Tasman Ranges region relative to regions to the south. Variations in thickness and rigidity of the Australian lithosphere possibly control N-S longitudinal changes, consistent with our estimates of increase in linear shortening from the Tasman Ranges to the regions located west of the Alpine Fault bend.

  19. Everglades National Park Including Biscayne National Park. Activity Book.

    ERIC Educational Resources Information Center

    Ruehrwein, Dick

    Intended to help elementary school children learn about the resources of the Everglades and Biscayne National Parks, this activity book includes information, puzzles, games, and quizzes. The booklet deals with concepts related to: (1) the seasons; (2) fire ecology; (3) water; (4) fish; (5) mammals; (6) mosquitos; (7) birds; (8) venomous snakes;…

  20. Solar system fault detection

    DOEpatents

    Farrington, Robert B.; Pruett, Jr., James C.

    1986-01-01

    A fault detecting apparatus and method are provided for use with an active solar system. The apparatus provides an indication as to whether one or more predetermined faults have occurred in the solar system. The apparatus includes a plurality of sensors, each sensor being used in determining whether a predetermined condition is present. The outputs of the sensors are combined in a pre-established manner in accordance with the kind of predetermined faults to be detected. Indicators communicate with the outputs generated by combining the sensor outputs to give the user of the solar system and the apparatus an indication as to whether a predetermined fault has occurred. Upon detection and indication of any predetermined fault, the user can take appropriate corrective action so that the overall reliability and efficiency of the active solar system are increased.

  1. Solar system fault detection

    DOEpatents

    Farrington, R.B.; Pruett, J.C. Jr.

    1984-05-14

    A fault detecting apparatus and method are provided for use with an active solar system. The apparatus provides an indication as to whether one or more predetermined faults have occurred in the solar system. The apparatus includes a plurality of sensors, each sensor being used in determining whether a predetermined condition is present. The outputs of the sensors are combined in a pre-established manner in accordance with the kind of predetermined faults to be detected. Indicators communicate with the outputs generated by combining the sensor outputs to give the user of the solar system and the apparatus an indication as to whether a predetermined fault has occurred. Upon detection and indication of any predetermined fault, the user can take appropriate corrective action so that the overall reliability and efficiency of the active solar system are increased.

  2. Activity on the multi-stranded Central Branch of the North Anatolian Fault along the southern shelf of the Marmara Sea, Turkey

    NASA Astrophysics Data System (ADS)

    Okay, S.; Sorlien, C. C.; Cifci, G.; Cormier, M. H.; Dondurur, D.; Steckler, M. S.; Barin, B.; Seeber, L.

    2014-12-01

    The North Anatolian Fault (NAF), a major continental transform boundary, splays westward into three branches in the Sea of Marmara region of NW Turkey. The main northern branch passes only ~20 km from Istanbul and has been the subject of intense investigation, The central branch enters the sea of Marmara in Gemlik Bay and extends westeward along the southern shelf of the Sea of Marmara. However, its detailed offshore geometry as well as its level of seismic activity have remained controversial. Under the SoMAR Project, two geophysical cruises were carried out in 2013 and 2014 to map the major sedimentary basins and shallow fault patterns of the southern shelf of the Marmara Sea. Including our 2008 and 2010 acquisition, we acquired 4,430 km of high-resolution multichannel seismic, sparker, multibeam bathymetric and CHIRP data. We used the new data to correlate our published late Quaternary stratigraphic age model across the outer shelf, and a ~1/4 Ma horizon across the Inner Shelf, thus providing a chronology that can be applied to the tectonic history of the central branch. As it exits Gemlik Bay, the central branch itself diverges westward into strands in a fan pattern. A half dozen southern strands strike WSW and W, with one continuing onland near the Kocasu River delta between Bandırma and Mudanya, and others dying out offshore. The northern strand strikes WNW and splays again into the İmrali Ridge Fault and the Imrali Fault across respectively the mid-shelf and the shelf break. A middle fault, the Kapidag fault, is present between Kapidag Peninsula and Marmara Island. Most of the faults increase their vertical component with depth, suggesting activity during Pliocene through Holocene time. The Kapidag fault and Imrali Ridge fault each exhibit between 1 and 2 km of vertical separation of acoustic basement. Late Quaternary rates of vertical separation on these faults can accumulate the total vertical component after Miocene time. Thus, steady-state activity is

  3. The Eastern Lower Tagus Valley Fault Zone in central Portugal: Active faulting in a low-deformation region within a major river environment

    NASA Astrophysics Data System (ADS)

    Canora, Carolina; Vilanova, Susana P.; Besana-Ostman, Glenda M.; Carvalho, João; Heleno, Sandra; Fonseca, Joao

    2015-10-01

    Active faulting in the Lower Tagus Valley, Central Portugal, poses a significant seismic hazard that is not well understood. Although the area has been affected by damaging earthquakes during historical times, only recently has definitive evidence of Quaternary surface faulting been found along the western side of the Tagus River. The location, geometry and kinematics of active faults along the eastern side of the Tagus valley have not been previously studied. We present the first results of mapping and paleoseismic analysis of the eastern strand of the Lower Tagus Valley Fault Zone (LTVFZ). Geomorphological, paleoseismological, and seismic reflection studies indicate that the Eastern LTVFZ is a left-lateral strike-slip fault. The detailed mapping of geomorphic features and studies in two paleoseismic trenches show that surface fault rupture has occurred at least six times during the past 10 ka. The river offsets indicate a minimum slip rate on the order of 0.14-0.24 mm/yr for the fault zone. Fault trace mapping, geomorphic analysis, and paleoseismic studies suggest a maximum magnitude for the Eastern LTVFZ of Mw ~ 7.3 with a recurrence interval for surface ruptures ~ 1.7 ka. At least two events occurred after 1175 ± 95 cal yr BP. Single-event displacements are unlikely to be resolved in the paleoseismic trenches, thus our observations most probably represent the minimum number of events identified in the trenches.

  4. Quaternary strike-slip crustal deformation around an active fault based on paleomagnetic analysis: a case study of the Enako fault in central Japan

    NASA Astrophysics Data System (ADS)

    Kimura, Haruo; Itoh, Yasuto; Tsutsumi, Hiroyuki

    2004-10-01

    To evaluate cumulative strike-slip deformation around an active fault, we carried out tectonic geomorphic investigations of the active right-lateral strike-slip Enako fault in central Japan and paleomagnetic investigations of the Kamitakara pyroclastic flow deposit (KPFD; 0.6 Ma welded tuff) distributed around the fault. Tectonic geomorphic study revealed that the strike-slip displacement on the fault is ca. 150 m during the past 600 ka. We carried out measurements of paleomagnetic directions and anisotropy of magnetic susceptibility (AMS) within the pyroclastic flow deposit. Stable primary magnetic directions at each sampling site are well clustered and the AMS fabric is very oblate. We then applied tilt correction of paleomagnetic directions at 15 sites using tilting data obtained by the AMS property and orientations of eutaxitic structures. Within a distance of about 500 m from the fault trace, differential clockwise rotations were detected; the rotation angle is larger for zones closer to the fault. Because of this relation and absence of block boundary faults, a continuous deformation model explains the crustal deformation in the study area. The calculated minimum value of strike-slip displacement associated with this deformation detected within the shear zone is 210 m. The sum of this and offset on the Enako fault is 360 m and the slip rate is estimated at 0.6 mm/year.

  5. Model-based fault detection and isolation for intermittently active faults with application to motion-based thruster fault detection and isolation for spacecraft

    NASA Technical Reports Server (NTRS)

    Wilson, Edward (Inventor)

    2008-01-01

    The present invention is a method for detecting and isolating fault modes in a system having a model describing its behavior and regularly sampled measurements. The models are used to calculate past and present deviations from measurements that would result with no faults present, as well as with one or more potential fault modes present. Algorithms that calculate and store these deviations, along with memory of when said faults, if present, would have an effect on the said actual measurements, are used to detect when a fault is present. Related algorithms are used to exonerate false fault modes and finally to isolate the true fault mode. This invention is presented with application to detection and isolation of thruster faults for a thruster-controlled spacecraft. As a supporting aspect of the invention, a novel, effective, and efficient filtering method for estimating the derivative of a noisy signal is presented.

  6. Connecting the Yakima fold and thrust belt to active faults in the Puget Lowland, Washington

    USGS Publications Warehouse

    Blakely, R.J.; Sherrod, B.L.; Weaver, C.S.; Wells, R.E.; Rohay, A.C.; Barnett, E.A.; Knepprath, N.E.

    2011-01-01

    High-resolution aeromagnetic surveys of the Cascade Range and Yakima fold and thrust belt (YFTB), Washington, provide insights on tectonic connections between forearc and back-arc regions of the Cascadia convergent margin. Magnetic surveys were measured at a nominal altitude of 250 m above terrain and along flight lines spaced 400 m apart. Upper crustal rocks in this region have diverse magnetic properties, ranging from highly magnetic rocks of the Miocene Columbia River Basalt Group to weakly magnetic sedimentary rocks of various ages. These distinctive magnetic properties permit mapping of important faults and folds from exposures to covered areas. Magnetic lineaments correspond with mapped Quaternary faults and with scarps identified in lidar (light detection and ranging) topographic data and aerial photography. A two-dimensional model of the northwest striking Umtanum Ridge fault zone, based on magnetic and gravity data and constrained by geologic mapping and three deep wells, suggests that thrust faults extend through the Tertiary section and into underlying pre-Tertiary basement. Excavation of two trenches across a prominent scarp at the base of Umtanum Ridge uncovered evidence for bending moment faulting possibly caused by a blind thrust. Using aeromagnetic, gravity, and paleoseismic evidence, we postulate possible tectonic connections between the YFTB in eastern Washington and active faults of the Puget Lowland. We suggest that faults and folds of Umtanum Ridge extend northwestward through the Cascade Range and merge with the Southern Whidbey Island and Seattle faults near Snoqualmie Pass 35 km east of Seattle. Recent earthquakes (MW ≤ 5.3) suggest that this confluence of faults may be seismically active today.

  7. Active Crustal Faults in the Forearc Region, Guerrero Sector of the Mexican Subduction Zone

    NASA Astrophysics Data System (ADS)

    Gaidzik, Krzysztof; Ramírez-Herrera, Maria Teresa; Kostoglodov, Vladimir

    2016-10-01

    This work explores the characteristics and the seismogenic potential of crustal faults on the overriding plate in an area of high seismic hazard associated with the occurrence of subduction earthquakes and shallow earthquakes of the overriding plate. We present the results of geomorphic, structural, and fault kinematic analyses conducted on the convergent margin between the Cocos plate and the forearc region of the overriding North American plate, within the Guerrero sector of the Mexican subduction zone. We aim to determine the active tectonic processes in the forearc region of the subduction zone, using the river network pattern, topography, and structural data. We suggest that in the studied forearc region, both strike-slip and normal crustal faults sub-parallel to the subduction zone show evidence of activity. The left-lateral offsets of the main stream courses of the largest river basins, GPS measurements, and obliquity of plate convergence along the Cocos subduction zone in the Guerrero sector suggest the activity of sub-latitudinal left-lateral strike-slip faults. Notably, the regional left-lateral strike-slip fault that offsets the Papagayo River near the town of La Venta named "La Venta Fault" shows evidence of recent activity, corroborated also by GPS measurements (4-5 mm/year of sinistral motion). Assuming that during a probable earthquake the whole mapped length of this fault would rupture, it would produce an event of maximum moment magnitude Mw = 7.7. Even though only a few focal mechanism solutions indicate a stress regime relevant for reactivation of these strike-slip structures, we hypothesize that these faults are active and suggest two probable explanations: (1) these faults are characterized by long recurrence period, i.e., beyond the instrumental record, or (2) they experience slow slip events and/or associated fault creep. The analysis of focal mechanism solutions of small magnitude earthquakes in the upper plate, for the period between 1995

  8. Eocene activity on the Western Sierra Fault System and its role incising Kings Canyon, California

    NASA Astrophysics Data System (ADS)

    Sousa, Francis J.; Farley, Kenneth A.; Saleeby, Jason; Clark, Marin

    2016-04-01

    Combining new and published apatite (U-Th)/He and apatite 4He/3He data from along the Kings River canyon, California we rediscover a west-down normal fault on the western slope of the southern Sierra Nevada, one of a series of scarps initially described by Hake (1928) which we call the Western Sierra Fault System. Integrating field observations with apatite (U-Th)/He data, we infer a single fault trace 30 km long, and constrain the vertical offset across this fault to be roughly a kilometer. Thermal modeling of apatite 4He/3He data documents a pulse of footwall cooling near the fault and upstream in the footwall at circa 45-40 Ma, which we infer to be the timing of a kilometer-scale incision pulse resulting from the fault activity. In the context of published data from the subsurface of the Sacramento and San Joaquin Valleys, our data from the Western Sierra Fault System suggests an Eocene tectonic regime dominated by low-to-moderate magnitude extension, surface uplift, and internal structural deformation of the southern Sierra Nevada and proximal Great Valley forearc.

  9. Late Cenozoic deformation of the Da'an-Dedu Fault Zone and its implications for the earthquake activities in the Songliao basin, NE China

    NASA Astrophysics Data System (ADS)

    Zhongyuan, Yu; Peizhen, Zhang; Wei, Min; Qinghai, Wei; Limei, Wang; Bin, Zhao; Shuang, Liu; Jian, Kang

    2015-08-01

    The Da'an-Dedu Fault Zone is a major tectonic feature cutting through the Songliao Basin from south to north in NE China. Five earthquakes with magnitudes over 5 that occurred during the past 30 years suggest the fault zone is a seismogenic structure with future seismic potential. The structural pattern, tectonic history, Quaternary activity and seismic potential have previously been unknown due to the Quaternary sedimentary coverage and lack of large historic earthquakes (M > 7). In this paper, we use seismic reflection profiles and drilling from petroleum explorations and shallow-depth seismic reflections to study those problems. The total length of the Da'an-Dedu Fault Zone is more than 400 km; modern seismicity delineates it into 4 segments each with a length of 90-100 km. In cross-section view, the folds and associated faults form a complex structural belt with a width of more than 10 km. Shallow-level seismic reflection across the Da'an-Dedu Fault Zone reveals that the Late Quaternary sediments were folded and faulted, indicating its present tectonic activity. The Da'an-Dedu Fault Zone and Songliao Basin have been subjected to three stages of tectonic evolution: a rifting stage characterized by normal faulting and extension (∼145-112 Ma), a prolonged stage of thermal subsidence (∼112-65 Ma), and a tectonic reversal that has been taking place since ∼65 Ma. Our shallow-level reflection profiles show that the folding and reverse faulting have influenced the Late Quaternary sediments. The seismicity and moderate earthquakes suggest that the tectonic activity persists today. The deformation rate across the Da'an-Dedu Fault Zone, however, is measured to be very slow. In conjunction with the inference that most deformation in NE China may be taken up by the Yilan-Yitong Fault Zone bounding the Songliao Basin to the east, we suggest moderate earthquake potential and thus moderate seismic hazards along the Da'an-Dedu Fault Zone. The geological structures, which

  10. Analecta of structures formed during the 28 June 1992 Landers-Big Bear, California earthquake sequence (including maps of shear zones, belts of shear zones, tectonic ridge, duplex en echelon fault, fault elements, and thrusts in restraining steps)

    SciTech Connect

    Johnson, A.M.; Johnson, N.A.; Johnson, K.M.; Wei, W.; Fleming, R.W.; Cruikshank, K.M.; Martosudarmo, S.Y.

    1997-12-31

    The June 28, 1992, M{sub s} 7.5 earthquake at Landers, California, which occurred about 10 km north of the community of Yucca Valley, California, produced spectacular ground rupturing more than 80 km in length (Hough and others, 1993). The ground rupturing, which was dominated by right-lateral shearing, extended along at least four distinct faults arranged broadly en echelon. The faults were connected through wide transfer zones by stepovers, consisting of right-lateral fault zones and tension cracks. The Landers earthquakes occurred in the desert of southeastern California, where details of ruptures were well preserved, and patterns of rupturing were generally unaffected by urbanization. The structures were varied and well-displayed and, because the differential displacements were so large, spectacular. The scarcity of vegetation, the aridity of the area, the compactness of the alluvium and bedrock, and the relative isotropy and brittleness of surficial materials collaborated to provide a marvelous visual record of the character of the deformation zones. The authors present a series of analecta -- that is, verbal clips or snippets -- dealing with a variety of structures, including belts of shear zones, segmentation of ruptures, rotating fault block, en echelon fault zones, releasing duplex structures, spines, and ramps. All of these structures are documented with detailed maps in text figures or in plates (in pocket). The purpose is to describe the structures and to present an understanding of the mechanics of their formation. Hence, most descriptions focus on structures where the authors have information on differential displacements as well as spatial data on the position and orientation of fractures.

  11. Fault finder

    DOEpatents

    Bunch, Richard H.

    1986-01-01

    A fault finder for locating faults along a high voltage electrical transmission line. Real time monitoring of background noise and improved filtering of input signals is used to identify the occurrence of a fault. A fault is detected at both a master and remote unit spaced along the line. A master clock synchronizes operation of a similar clock at the remote unit. Both units include modulator and demodulator circuits for transmission of clock signals and data. All data is received at the master unit for processing to determine an accurate fault distance calculation.

  12. Intelligent fault management for the Space Station active thermal control system

    NASA Technical Reports Server (NTRS)

    Hill, Tim; Faltisco, Robert M.

    1992-01-01

    The Thermal Advanced Automation Project (TAAP) approach and architecture is described for automating the Space Station Freedom (SSF) Active Thermal Control System (ATCS). The baseline functionally and advanced automation techniques for Fault Detection, Isolation, and Recovery (FDIR) will be compared and contrasted. Advanced automation techniques such as rule-based systems and model-based reasoning should be utilized to efficiently control, monitor, and diagnose this extremely complex physical system. TAAP is developing advanced FDIR software for use on the SSF thermal control system. The goal of TAAP is to join Knowledge-Based System (KBS) technology, using a combination of rules and model-based reasoning, with conventional monitoring and control software in order to maximize autonomy of the ATCS. TAAP's predecessor was NASA's Thermal Expert System (TEXSYS) project which was the first large real-time expert system to use both extensive rules and model-based reasoning to control and perform FDIR on a large, complex physical system. TEXSYS showed that a method is needed for safely and inexpensively testing all possible faults of the ATCS, particularly those potentially damaging to the hardware, in order to develop a fully capable FDIR system. TAAP therefore includes the development of a high-fidelity simulation of the thermal control system. The simulation provides realistic, dynamic ATCS behavior and fault insertion capability for software testing without hardware related risks or expense. In addition, thermal engineers will gain greater confidence in the KBS FDIR software than was possible prior to this kind of simulation testing. The TAAP KBS will initially be a ground-based extension of the baseline ATCS monitoring and control software and could be migrated on-board as additional computation resources are made available.

  13. Southern San Andreas Fault evaluation field activity: approaches to measuring small geomorphic offsets--challenges and recommendations for active fault studies

    USGS Publications Warehouse

    Scharer, Katherine M.; Salisbury, J. Barrett; Arrowsmith, J. Ramon; Rockwell, Thomas K.

    2014-01-01

    In southern California, where fast slip rates and sparse vegetation contribute to crisp expression of faults and microtopography, field and high‐resolution topographic data (<1  m/pixel) increasingly are used to investigate the mark left by large earthquakes on the landscape (e.g., Zielke et al., 2010; Zielke et al., 2012; Salisbury, Rockwell, et al., 2012, Madden et al., 2013). These studies measure offset streams or other geomorphic features along a stretch of a fault, analyze the offset values for concentrations or trends along strike, and infer that the common magnitudes reflect successive surface‐rupturing earthquakes along that fault section. Wallace (1968) introduced the use of such offsets, and the challenges in interpreting their “unique complex history” with offsets on the Carrizo section of the San Andreas fault; these were more fully mapped by Sieh (1978) and followed by similar field studies along other faults (e.g., Lindvall et al., 1989; McGill and Sieh, 1991). Results from such compilations spurred the development of classic fault behavior models, notably the characteristic earthquake and slip‐patch models, and thus constitute an important component of the long‐standing contrast between magnitude–frequency models (Schwartz and Coppersmith, 1984; Sieh, 1996; Hecker et al., 2013). The proliferation of offset datasets has led earthquake geologists to examine the methods and approaches for measuring these offsets, uncertainties associated with measurement of such features, and quality ranking schemes (Arrowsmith and Rockwell, 2012; Salisbury, Arrowsmith, et al., 2012; Gold et al., 2013; Madden et al., 2013). In light of this, the Southern San Andreas Fault Evaluation (SoSAFE) project at the Southern California Earthquake Center (SCEC) organized a combined field activity and workshop (the “Fieldshop”) to measure offsets, compare techniques, and explore differences in interpretation. A thorough analysis of the measurements from the

  14. Modeling of fault activation and seismicity by injection directly into a fault zone associated with hydraulic fracturing of shale-gas reservoirs

    DOE PAGES

    Rutqvist, Jonny; Rinaldi, Antonio P.; Cappa, Frédéric; ...

    2015-03-01

    We conducted three-dimensional coupled fluid-flow and geomechanical modeling of fault activation and seismicity associated with hydraulic fracturing stimulation of a shale-gas reservoir. We simulated a case in which a horizontal injection well intersects a steeply dip- ping fault, with hydraulic fracturing channeled within the fault, during a 3-hour hydraulic fracturing stage. Consistent with field observations, the simulation results show that shale-gas hydraulic fracturing along faults does not likely induce seismic events that could be felt on the ground surface, but rather results in numerous small microseismic events, as well as aseismic deformations along with the fracture propagation. The calculated seismicmore » moment magnitudes ranged from about -2.0 to 0.5, except for one case assuming a very brittle fault with low residual shear strength, for which the magnitude was 2.3, an event that would likely go unnoticed or might be barely felt by humans at its epicenter. The calculated moment magnitudes showed a dependency on injection depth and fault dip. We attribute such dependency to variation in shear stress on the fault plane and associated variation in stress drop upon reactivation. Our simulations showed that at the end of the 3-hour injection, the rupture zone associated with tensile and shear failure extended to a maximum radius of about 200 m from the injection well. The results of this modeling study for steeply dipping faults at 1000 to 2500 m depth is in agreement with earlier studies and field observations showing that it is very unlikely that activation of a fault by shale-gas hydraulic fracturing at great depth (thousands of meters) could cause felt seismicity or create a new flow path (through fault rupture) that could reach shallow groundwater resources.« less

  15. Modeling of fault activation and seismicity by injection directly into a fault zone associated with hydraulic fracturing of shale-gas reservoirs

    SciTech Connect

    Rutqvist, Jonny; Rinaldi, Antonio P.; Cappa, Frédéric; Moridis, George J.

    2015-03-01

    We conducted three-dimensional coupled fluid-flow and geomechanical modeling of fault activation and seismicity associated with hydraulic fracturing stimulation of a shale-gas reservoir. We simulated a case in which a horizontal injection well intersects a steeply dip- ping fault, with hydraulic fracturing channeled within the fault, during a 3-hour hydraulic fracturing stage. Consistent with field observations, the simulation results show that shale-gas hydraulic fracturing along faults does not likely induce seismic events that could be felt on the ground surface, but rather results in numerous small microseismic events, as well as aseismic deformations along with the fracture propagation. The calculated seismic moment magnitudes ranged from about -2.0 to 0.5, except for one case assuming a very brittle fault with low residual shear strength, for which the magnitude was 2.3, an event that would likely go unnoticed or might be barely felt by humans at its epicenter. The calculated moment magnitudes showed a dependency on injection depth and fault dip. We attribute such dependency to variation in shear stress on the fault plane and associated variation in stress drop upon reactivation. Our simulations showed that at the end of the 3-hour injection, the rupture zone associated with tensile and shear failure extended to a maximum radius of about 200 m from the injection well. The results of this modeling study for steeply dipping faults at 1000 to 2500 m depth is in agreement with earlier studies and field observations showing that it is very unlikely that activation of a fault by shale-gas hydraulic fracturing at great depth (thousands of meters) could cause felt seismicity or create a new flow path (through fault rupture) that could reach shallow groundwater resources.

  16. Delineation of Active Basement Faults in the Eastern Tennessee and Charlevoix Intraplate Seismic Zones

    NASA Astrophysics Data System (ADS)

    Powell, C. A.; Langston, C. A.; Cooley, M.

    2013-12-01

    Recognition of distinct, seismogenic basement faults within the eastern Tennessee seismic zone (ETSZ) and the Charlevoix seismic zone (CSZ) is now possible using local earthquake tomography and datasets containing a sufficiently large number of earthquakes. Unlike the New Madrid seismic zone where seismicity clearly defines active fault segments, earthquake activity in the ETSZ and CSZ appears diffuse. New arrival time inversions for hypocenter relocations and 3-D velocity variations using datasets in excess of 1000 earthquakes suggest the presence of distinct basement faults in both seismic zones. In the ETSZ, relocated hypocenters align in near-vertical segments trending NE-SW, parallel to the long dimension of the seismic zone. Earthquakes in the most seismogenic portion of the ETSZ delineate another set of near-vertical faults trending roughly E-ESE. These apparent trends and steep dips are compatible with ETSZ focal mechanism solutions. The solutions are remarkably consistent and indicate strike-slip motion along the entire length of the seismic zone. Relocated hypocenter clusters in the CSZ define planes that trend and dip in directions that are compatible with known Iapitan rift faults. Seismicity defining the planes becomes disrupted where the rift faults encounter a major zone of deformation produced by a Devonian meteor impact. We will perform a joint statistical analysis of hypocenter alignments and focal mechanism nodal plane orientations in the ETSZ and the CSZ to determine the spatial orientations of dominant seismogenic basement faults. Quantifying the locations and dimensions of active basement faults will be important for seismic hazard assessment and for models addressing the driving mechanisms for these intraplate zones.

  17. Paper 58714 - Exploring activated faults hydromechanical processes from semi-controled field injection experiments

    NASA Astrophysics Data System (ADS)

    Guglielmi, Y.; Cappa, F.; Nussbaum, C.

    2015-12-01

    The appreciation of the sensitivity of fractures and fault zones to fluid-induced-deformations in the subsurface is a key question in predicting the reservoir/caprock system integrity around fluid manipulations with applications to reservoir leakage and induced seismicity. It is also a question of interest in understanding earthquakes source, and recently the hydraulic behavior of clay faults under a potential reactivation around nuclear underground depository sites. Fault and fractures dynamics studies face two key problems (1) the up-scaling of laboratory determined properties and constitutive laws to the reservoir scale which is not straightforward when considering faults and fractures heterogeneities, (2) the difficulties to control both the induced seismicity and the stimulated zone geometry when a fault is reactivated. Using instruments dedicated to measuring coupled pore pressures and deformations downhole, we conducted field academic experiments to characterize fractures and fault zones hydromechanical properties as a function of their multi-scale architecture, and to monitor their dynamic behavior during the earthquake nucleation process. We show experiments on reservoir or cover rocks analogues in underground research laboratories where experimental conditions can be optimized. Key result of these experiments is to highlight how important the aseismic fault activation is compared to the induced seismicity. We show that about 80% of the fault kinematic moment is aseismic and discuss the complex associated fault friction coefficient variations. We identify that the slip stability and the slip velocity are mainly controlled by the rate of the permeability/porosity increase, and discuss the conditions for slip nucleation leading to seismic instability.

  18. Probabilistic seismic hazard study based on active fault and finite element geodynamic models

    NASA Astrophysics Data System (ADS)

    Kastelic, Vanja; Carafa, Michele M. C.; Visini, Francesco

    2016-04-01

    We present a probabilistic seismic hazard analysis (PSHA) that is exclusively based on active faults and geodynamic finite element input models whereas seismic catalogues were used only in a posterior comparison. We applied the developed model in the External Dinarides, a slow deforming thrust-and-fold belt at the contact between Adria and Eurasia.. is the Our method consists of establishing s two earthquake rupture forecast models: (i) a geological active fault input (GEO) model and, (ii) a finite element (FEM) model. The GEO model is based on active fault database that provides information on fault location and its geometric and kinematic parameters together with estimations on its slip rate. By default in this model all deformation is set to be released along the active faults. The FEM model is based on a numerical geodynamic model developed for the region of study. In this model the deformation is, besides along the active faults, released also in the volumetric continuum elements. From both models we calculated their corresponding activity rates, its earthquake rates and their final expected peak ground accelerations. We investigated both the source model and the earthquake model uncertainties by varying the main active fault and earthquake rate calculation parameters through constructing corresponding branches of the seismic hazard logic tree. Hazard maps and UHS curves have been produced for horizontal ground motion on bedrock conditions VS 30 ≥ 800 m/s), thereby not considering local site amplification effects. The hazard was computed over a 0.2° spaced grid considering 648 branches of the logic tree and the mean value of 10% probability of exceedance in 50 years hazard level, while the 5th and 95th percentiles were also computed to investigate the model limits. We conducted a sensitivity analysis to control which of the input parameters influence the final hazard results in which measure. The results of such comparison evidence the deformation model and

  19. Recently Active Traces of the Berryessa Fault, California: A Digital Database

    USGS Publications Warehouse

    Lienkaemper, James J.

    2012-01-01

    The purpose of this map is to show the location of and evidence for recent movement on active fault traces within the Berryessa section and parts of adjacent sections of the Green Valley Fault Zone, California. The location and recency of the mapped traces is primarily based on geomorphic expression of the fault as interpreted from large-scale 2010 aerial photography and from 2007 and 2011 0.5 and 1.0 meter bare-earth LiDAR imagery (that is, high-resolution topographic data). In a few places, evidence of fault creep and offset Holocene strata in trenches and natural exposures have confirmed the activity of some of these traces. This publication is formatted both as a digital database for use within a geographic information system (GIS) and for broader public access as map images that may be browsed on-line or download a summary map. The report text describes the types of scientific observations used to make the map, gives references pertaining to the fault and the evidence of faulting, and provides guidance for use of and limitations of the map.

  20. Unravelling the competing influence of regional uplift and active normal faulting in SW Calabria, Italy

    NASA Astrophysics Data System (ADS)

    Whittaker, Alex; Roda Boluda, Duna; Boulton, Sarah; Erhardt, Sebastian

    2015-04-01

    The Neogene geological and geomorphological evolution of Southern Italy is complex and is fundamentally controlled by the subduction of the Ionian slab along the Apennine belt from the Calabrian Arc, and back-arc extension driven by trench rollback. In the area of Calabria and the Straits of Messina the presence of (i) uplifted, deformed and dissected basin sediments and marine terraces, ranging in age from the early to mid-Pleistocene and (ii) seismicity associated with NE-SW normal faults that have well-developed footwall topography and triangular facets have led workers to suggest that both significant regional uplift and extensional faulting in SW Calabria have played a role in generating relief in the area since the mid Pleistocene. However, there is considerable uncertainty in the rates of total surface uplift relative to sea level in both time and space, and the relative partitioning of this uplift between a mantle-driven regional signal, potentially related to a slab tear, and the active extensional structures. Additionally, despite the widespread recognition of normal faults in Calabria to which historical earthquakes are often linked, there is much less agreement on (i) which ones are active and for what length of time; (ii) how the faults interact; and (iii) what their throw and throw rates are. In particular, the ability to resolve both regional uplift and normal faulting in SW Calabria is essential in order to fully understand the tectonic history of the region, while an understanding of location and slip rate of active faults, in an area where the population numbers more than two million people, is essential to assess regional seismic hazards. Here we address these important questions using a combination of tectonic geomorphology and structural geology. We critically examine existing constraints on the rates and distribution of active normal faulting and regional uplift in the area, and we derive new constraints on the along-strike variation in throw

  1. Identifying active interplate and intraplate fault zones in the western Caribbean plate from seismic reflection data and the significance of the Pedro Bank fault zone in the tectonic history of the Nicaraguan Rise

    NASA Astrophysics Data System (ADS)

    Ott, B.; Mann, P.

    2015-12-01

    The offshore Nicaraguan Rise in the western Caribbean Sea is an approximately 500,000 km2 area of Precambrian to Late Cretaceous tectonic terranes that have been assembled during the Late Cretaceous formation of the Caribbean plate and include: 1) the Chortis block, a continental fragment; 2) the Great Arc of the Caribbean, a deformed Cretaceous arc, and 3) the Caribbean large igneous province formed in late Cretaceous time. Middle Eocene to Recent eastward motion of the Caribbean plate has been largely controlled by strike-slip faulting along the northern Caribbean plate boundary zone that bounds the northern margin of the Nicaraguan Rise. These faults reactivate older rift structures near the island of Jamaica and form the transtensional basins of the Honduran Borderlands near Honduras. Recent GPS studies suggest that small amount of intraplate motion within the current margin of error of GPS measurements (1-3 mm/yr) may occur within the center of the western Caribbean plate at the Pedro Bank fault zone and Hess Escarpment. This study uses a database of over 54,000 km of modern and vintage 2D seismic data, combined with earthquake data and results from previous GPS studies to define the active areas of inter- and intraplate fault zones in the western Caribbean. Intraplate deformation occurs along the 700-km-long Pedro Bank fault zone that traverses the center of the Nicaraguan Rise and reactivates the paleo suture zone between the Great Arc of the Caribbean and the Caribbean large igneous province. The Pedro Bank fault zone also drives active extension at the 200-km-long San Andres rift along the southwest margin of the Nicaraguan Rise. Influence of the Cocos Ridge indentor may be contributing to reactivation of faulting along the southwesternmost, active segment of the Hess Escarpment.

  2. Slip Rates of Main Active Fault Zones Through Turkey Inferred From GPS Observations

    NASA Astrophysics Data System (ADS)

    Ozener, H.; Aktug, B.; Dogru, A.; Tasci, L.; Acar, M.; Emre, O.; Yilmaz, O.; Turgut, B.; Halicioglu, K.; Sabuncu, A.; Bal, O.; Eraslan, A.

    2015-12-01

    Active Fault Map of Turkey was revised and published by General Directorate of Mineral Research and Exploration in 2012. This map reveals that there are about 500 faults can generate earthquakes.In order to understand the earthquake potential of these faults, it is needed to determine the slip rates. Although many regional and local studies were performed in the past, the slip rates of the active faults in Turkey have not been determined. In this study, the block modelling, which is the most common method to produce slip rates, will be done. GPS velocities required for block modeling is being compiled from the published studies and the raw data provided then velocity field is combined. To form a homogeneous velocity field, different stochastic models will be used and the optimal velocity field will be achieved. In literature, GPS site velocities, which are computed for different purposes and published, are combined globally and this combined velocity field are used in the analysis of strain accumulation. It is also aimed to develop optimal stochastic models to combine the velocity data. Real time, survey mode and published GPS observations is being combined in this study. We also perform new GPS observations. Furthermore, micro blocks and main fault zones from Active Fault Map Turkey will be determined and homogeneous velocity field will be used to infer slip rates of these active faults. Here, we present the result of first year of the study. This study is being supported by THE SCIENTIFIC AND TECHNOLOGICAL RESEARCH COUNCIL OF TURKEY (TUBITAK)-CAYDAG with grant no. 113Y430.

  3. A rod-type creepmeter for measurement of displacement in active fault zone

    NASA Astrophysics Data System (ADS)

    Lee, J.-C.; Jeng, F.-S.; Chu, H.-T.; Angelier, J.; Hu, J.-C.

    2000-05-01

    A creepmeter has been developed to monitor gradual displacements of near-surface movement in an active fault zone. This rod-type creepmeter is a robust, low-cost instrument that is simple to construct and install. This creepmeter consists of two 3-m invar rods attached to anchored steel piers at each end, straddling the surface traces of active fault. The invar rods are supported by a pair of U-shaped solid steel girders. A mechanical dial-gauge sensor in the middle of the creepmeter is adopted to record the displacement of fault creep, and has a precision of 0.01 mm. Because the creepmeter is installed on the surface, the temperature effect is important. To calibrate and correct for the temperature effect, we carried out hourly measurements over a period of 30 hours to calculate the thermal expansion coefficients for each creepmeter. Thermal corrections could thus be made when readings were taken. Five of these creepmeters have been installed in the Chihshang active fault zone of eastern Taiwan, in the present collision suture zone between the Philippine Sea plate and the Eurasian plate. Readings taken over one year have shown that this rod-type creepmeter is effective in providing a near-continuous record of active fault creep with a good precision.

  4. Interactions between active faulting, volcanism, and sedimentary processes at an island arc: Insights from Les Saintes channel, Lesser Antilles arc

    NASA Astrophysics Data System (ADS)

    Leclerc, F.; Feuillet, N.; Deplus, C.

    2016-07-01

    New high-resolution marine geophysical data allow to characterize a large normal fault system in the Lesser Antilles arc, and to investigate the interactions between active faulting, volcanism, sedimentary, and mass-wasting processes. Les Saintes fault system is composed of several normal faults that form a 30 km wide half-graben accommodating NE-SW extension. It is bounded by the Roseau fault, responsible for the destructive Mw 6.3 21 November 2004 earthquake. The Roseau fault has been identified from the island of Basse-Terre to Dominica. It is thus 40 km long, and it could generate Mw 7 earthquakes in the future. Several submarine volcanoes are also recognized. We show that the fault system initiated after the main volcanic construction and subsequently controls the emission of volcanic products. The system propagates southward through damage zones. At the tip of the damage zones, several volcanic cones were recently emplaced probably due to fissures opening in an area of stress increase. A two-way interaction is observed between active faulting and sedimentary processes. The faults control the development of the main turbiditic system made of kilometer-wide canyons, as well as the location of sediment ponding. In turn, erosion and sedimentation prevent scarp growth at the seafloor. Faulting also enhances mass-wasting processes. Since its initiation, the fault system has consequently modified the morphologic evolution of the arc through perturbation of the sedimentary processes and localization of the more recent volcanic activity.

  5. Evaluating knickpoint recession along an active fault for paleoseismological analysis: The Huoshan Piedmont, Eastern China

    NASA Astrophysics Data System (ADS)

    Wei, Zhanyu; Bi, Lisi; Xu, Yueren; He, Honglin

    2015-04-01

    Ground-rupturing earthquakes can generate tectonic knickpoints within upstream reaches of streams across active fault zones. These knickpoints are characteristic of upstream propagation of time-related process once generated by an earthquake, so analysis of knickpoint series in streams which cross fault zones can be used to infer paleoearthquake events. We studied the knickpoints along the Huoshan Piedmont Fault (HPF), which is an active normal fault in the Shanxi Faulted Basin zone, China, and demonstrate that analysis of knickpoints shows evidence for two paleoearthquakes in the HPF. First, we identified knickpoints in bedrock reaches upstream of the HPF using high-resolution DEMs derived from IRS-P5 stereo images and the stream-gradient method. After excluding non-faulting knickpoints, 47 knickpoints were identified in 23 bedrock reaches upstream from the HPF. Analysis of the most recent knickpoints caused by the 1303 CE Hongdong Earthquake allowed for local calibration of the retreat rates. Applying these retreat rates across the study area allows for the estimation of the age of other knickpoints, and constrains the age ranges of two knickpoint groups to be 2269-3336 a BP and 4504-5618 a BP. These ages constrain the ages of two paleoearthquake events at 2710 ± 102 and 4980 ± 646 a BP. The knickpoints along the HPF obey the parallel retreating model in which knickpoint morphology was roughly maintained during retreat, so the heights of knickpoints represent the coseismic vertical displacements generated by the earthquakes along the HPF. The vertical offsets for these three earthquake events are similar and are approximately 4 m, which indicates that the ruptures on the HPF obey a characteristic slip model with a similar slip distribution for several successive earthquakes. These results provide additional evidence of paleoearthquakes on the HPF and show that analysis of knickpoint recession along an active fault is a valuable tool for paleoseismology.

  6. Low resistivity and permeability in actively deforming shear zones on the San Andreas Fault at SAFOD

    USGS Publications Warehouse

    Morrow, Carolyn A.; Lockner, David A.; Hickman, Stephen H.

    2015-01-01

    The San Andreas Fault Observatory at Depth (SAFOD) scientific drillhole near Parkfield, California crosses the San Andreas Fault at a depth of 2.7 km. Downhole measurements and analysis of core retrieved from Phase 3 drilling reveal two narrow, actively deforming zones of smectite-clay gouge within a roughly 200 m-wide fault damage zone of sandstones, siltstones and mudstones. Here we report electrical resistivity and permeability measurements on core samples from all of these structural units at effective confining pressures up to 120 MPa. Electrical resistivity (~10 ohm-m) and permeability (10-21 to 10-22 m2) in the actively deforming zones were one to two orders of magnitude lower than the surrounding damage zone material, consistent with broader-scale observations from the downhole resistivity and seismic velocity logs. The higher porosity of the clay gouge, 2 to 8 times greater than that in the damage zone rocks, along with surface conduction were the principal factors contributing to the observed low resistivities. The high percentage of fine-grained clay in the deforming zones also greatly reduced permeability to values low enough to create a barrier to fluid flow across the fault. Together, resistivity and permeability data can be used to assess the hydrogeologic characteristics of the fault, key to understanding fault structure and strength. The low resistivities and strength measurements of the SAFOD core are consistent with observations of low resistivity clays that are often found in the principal slip zones of other active faults making resistivity logs a valuable tool for identifying these zones.

  7. Geometry and faults tectonic activity of the Okavango Rift Zone, Botswana: Evidence from magnetotelluric and electrical resistivity tomography imaging

    NASA Astrophysics Data System (ADS)

    Bufford, Kelsey Mosley; Atekwana, Estella A.; Abdelsalam, Mohamed G.; Shemang, Elijah; Atekwana, Eliot A.; Mickus, Kevin; Moidaki, Moikwathai; Modisi, Motsoptse P.; Molwalefhe, Loago

    2012-04-01

    We used Magnetotelluric (MT) and Electrical Resistivity Tomography (ERT) to investigate the geometry and nature of faults activity of the Okavango Rift Zone (ORZ) in Botswana, an incipient rift at the southern tip of the Southwestern Branch of the East African Rift System. The ORZ forms a subtle topographic depression filled with Quaternary lacustrine and fluvio-deltaic sediments and is bounded by NE-trending normal faults that are more prominent in the southeastern portion of the rift basin. An MT model from a regional (˜140 km) NW-SE trending MT transect shows that much of the rift basin is underlain by a broad asymmetrical low resistivity anomaly that slopes gently (˜1°) from NW to SE reaching a depth of ˜300 m. This anomaly suggests that faults in the southeastern part of the rift form a NW-dipping border fault zone and that the lacustrine and fluvio-deltaic sediments contain brackish to saline water filling the broad half-graben structure. Furthermore, MT and ERT models from detailed (4-13 km long) MT transects and resistivity profiles show that one border fault (Thamalakane) and two within-basin faults (Lecha and Tsau) in the southeastern part of the ORZ are characterized by a localized high conductivity anomaly while another border fault (Kunyere) lacks such an anomaly. These localized anomalies are attributed to channelized fresh surface water and saline groundwater percolating through these faults forming "fault zone conductors" and suggest actively displacing faults. The lack of a "fault zone conductor" in the Kunyere fault is interpreted as indicating diminishing displacement on this fault, and that strain was transferred to the Thamalakane fault further to the east. The fluids provide lubricant for the ORZ faults, hence preventing infrequent large magnitude earthquakes, but favoring frequent micro-seismicity.

  8. Faults paragenesis and paleostress state in the zone of actively propagating continental strike-slip on the example of North Khangai fault (Northern Mongolia)

    NASA Astrophysics Data System (ADS)

    Sankov, Vladimir; Parfeevets, Anna

    2014-05-01

    Sublatitudinal North Khangai fault extends from Ubsunuur basin to the eastern part of the Selenga corridor trough 800 km. It is the northern boundary of the massive Mongolian block and limits of the Baikal rift system structures propagation in the south (Logatchev, 2003). Late Cenozoic and present-day fault activity are expressed in the left-lateral displacements of a different order of river valleys and high seismicity. We have carried out studies of the kinematics of active faults and palaeostresses reconstruction in the zone of the dynamic influence of North Khangai fault, the width of which varies along the strike and can exceeds 100 km. The result shows that the fault zone has a longitudinal and a transverse zoning. Longitudinal zonation presented gradual change from west to east regions of compression and transpression regimes (Khan-Khukhey ridge) to strike-slip regime (Bolnay ridge) and strike-slip and transtensive regimes (west of Selenga corridor). Strike-slip zones are represented by linearly concentrated rupture deformations. In contrast, near the termination of the fault the cluster fault deformation formed. Here, from north to south, there are radical changes in the palaeostress state. In the north-western sector (east of Selenga corridor) strike-slip faults, strike-slip faults with normal components and normal faults are dominated. For this sector the stress tensors of extensive, transtension and strike-slip regimes are typical. South-western sector is separated from the north-eastern one by massive Buren Nuruu ridge within which the active faults are not identified. In the south-western sector between the Orkhon and Tola rivers the cluster of NW thrusts and N-S strike-slip faults with reverse component are discovered. The faults are perfectly expressed by NW and N-S scarps in the relief. The most structures dip to the east and north-east. Holocene fault activity is demonstrated by the hanging river valleys and horizontal displacements with amplitudes

  9. Increased radon-222 in soil gas because of cumulative seismicity at active faults

    NASA Astrophysics Data System (ADS)

    Koike, Katsuaki; Yoshinaga, Tohru; Ueyama, Takayoshi; Asaue, Hisafumi

    2014-12-01

    This study demonstrates how the radon-222 (222Rn) concentration of soil gas at an active fault is sensitive to cumulative recent seismicity by examining seven active faults in western Japan. The 222Rn concentration was found to correlate well with the total earthquake energy within a 100-km radius of each fault. This phenomenon can probably be ascribed to the increase of pore pressure around the source depth of 222Rn in shallow soil caused by frequently induced strain. This increase in pore pressure can enhance the ascent velocity of 222Rn carrier gas as governed by Darcy's law. Anomalous 222Rn concentrations are likely to originate from high gas velocities, rather than increased accumulations of parent nuclides. The high velocities also can yield unusual young gas under the radioactive nonequilibrium condition of short elapsed time since 222Rn generation. The results suggest that ongoing seismicity in the vicinity of an active fault can cause accumulation of strain in shallow fault soils. Therefore, the 222Rn concentration is a possible gauge for the degree of strain accumulation.

  10. Characterising Active Fault Earthquake Sources Beneath the Coastal Environments of Christchurch and Wellington Cities, New Zealand, Using Seismic Reflection Profiles and Fault Displacement Analysis Techniques

    NASA Astrophysics Data System (ADS)

    Barnes, P.; Nodder, S.; Gorman, A. R.; Woelz, S.; Orpin, A. R.

    2014-12-01

    The coastal cities of Christchurch and Wellington, New Zealand, lie in different tectonic settings within the obliquely convergent Pacific-Australian plate boundary zone. Both cities have experienced damaging earthquakes in the last three years, which highlight the importance of locating and characterising hidden active faults close to urban areas. The devastating and geologically complex Canterbury earthquake sequence of 2010-2012 developed on the periphery of the plate boundary, and reactivated several previously unidentified strike-slip and reverse faults. Major aftershocks initially beneath land, generally migrated eastward over time, and finally advanced offshore into Pegasus Bay. A study of active submarine faulting beneath the bay highlights the role of inherited crustal structure and inversion tectonics. Marine seismic reflection data reveals that faults have very low slip rate and negligible post-glacial (<15 ka) deformation, which is consistent with inferred long recurrence intervals between large magnitude (Mw>6) earthquakes. Wellington City is surrounded by numerous high-slip rate strike-slip faults overlying the Hikurangi subduction zone. A dense network of secondary basement structures previously recognised throughout the region, mainly from tectonic geomorphology, have, until recently, been considered mostly inactive and excluded from seismic hazard models. We used high-resolution geophysical, bathymetric and sediment-core data to determine the structure, earthquake history and earthquake potential of a newly discovered active reverse fault beneath the inner reaches of Wellington Harbour. The fault has a slip rate of ~0.6 ± 0.3 mm/y, and a vertical displacement history indicating at least two large magnitude (Mw 6.3-7.1), surface-rupturing earthquakes in the last 10 ka. We infer that the fault extends southwards onshore beneath the city and potentially into Cook Strait, and represents a significant previously unrecognised seismic hazard.

  11. Preliminary results on the tectonic activity of the Ovacık Fault (Malatya-Ovacık Fault Zone, Turkey): Implications of the morphometric analyses

    NASA Astrophysics Data System (ADS)

    Yazıcı, Müge; Zabci, Cengiz; Sançar, Taylan; Sunal, Gürsel; Natalin, Boris A.

    2016-04-01

    , are mostly seen at the NE part of the study region. We observe several knick points along the longitudinal channel profiles that mostly fits to the surface trace of the OF. The existence of multiple knick points along the same channel profiles on the southwestern sections of the fault are interpreted to be the result of multiple parallel/sub-parallel branches of the OF in this region. The integrated preliminary results of all applied methods indicate the evidence of a stronger deformation at the northeastern part of the OF, in addition to the OB section. The deformation significantly diffuses to the southwest of the OB, where the main fault bifurcates into several branches. In order to explain the distribution of the deformation style along the OF, we suggest three hypotheses: (a) the OF is confined within a very narrow zone in its most northeastern parts, and the total strain is distributed at its southwestern section (especially to the southwest of the OB), (b) The high asymmetric values, calculated at the northeastern OF, are mainly affected by another major tectonic structure, the North Anatolian Shear Zone, at this region or (c) the combined effect of these two settings. Our further studies, which will include the analyzing the lithological properties of drainage basins, detailed fault mapping, and understanding the cumulative horizontal slip by constructing and comparing the pseudo-palaeotopography at both sides of the fault, are going to provide more detailed information on the activity and the style of deformation along the OF. This study is supported by TÜBİTAK project no. 114Y227. References -AFAD, 2013, Son 48 saatte 48 deprem (48 earthquakes at the last 48 hours) http://www.afad.gov.tr/TR/HaberDetay.aspx?IcerikID=1511&ID=12, Volume 2013. -Aktuǧ, B., Dikmen, Ü., Doǧru, A., and Özener, H., 2013, Seismicity and strain accumulation around Karliova Triple Junction (Turkey): Journal of Geodynamics, v. 67, no. 0, p. 21-29. -Şengör, A. M. C., Görür, N

  12. Paleoseismic and geomorphologic evidence of recent tectonic activity of the Pozohondo Fault (Betic Cordillera, SE Spain)

    USGS Publications Warehouse

    Rodríguez-Pascua, M.A.; Pérez-López, R.; Garduño-Monroy, V.H.; Giner-Robles, J.L.; Silva, P.G.; Perucha-Atienza, M.A.; Hernández-Madrigal, V.M.; Bischoff, J.

    2012-01-01

    Instrumental and historical seismicity in the Albacete province (External Prebetic Zone) has been scarcely recorded. However, major strike-slip faults showing NW-SE trending provide geomorphologic and paleoseismic evidence of recent tectonic activity (Late Pleistocene to Present). Moreover, these faults are consistently well oriented under the present stress tensor and therefore, they can trigger earthquakes of magnitude greater than M6, according to the lengths of surface ruptures and active segments recognized in fieldwork. Present landscape nearby the village of Hellin (SE of Albacete) is determined by the recent activity of the Pozohondo Fault (FPH), a NW-SE right-lateral fault with 90 km in length. In this study, we have calculated the Late Quaternary tectonic sliprate of the FPH from geomorphological, sedimentological, archaeoseimological, and paleoseismological approaches. All of these data suggest that the FPH runs with a minimum slip-rate of 0.1 mm/yr during the last 100 kyrs (Upper Pleistocene-Holocene). In addition, we have recognized the last two major paleoearthquakes associated to this fault. Magnitudes of these paleoearthquakes were gretarer than M6 and their recurrence intervals ranged from 6600 to 8600 yrs for the seismic cycle of FPH. The last earthquake was dated between the 1st and 6th centuries, though two earthquakes could be interpreted in this wide time interval, one at the FPH and other from a far field source. Results obtained here, suggest an increasing of the tectonic activity of the Pozohondo Fault during the last 10,000 yrs.

  13. Active Faults of the Northwest Himalaya: Pattern, Rate, and Timing of Surface Rupturing Earthquakes

    NASA Astrophysics Data System (ADS)

    Yule, J.; Madden, C.; Gavillot, Y.; Hebeler, A.; Meigs, A.; Hussein, A.; Malik, M.; Bhat, M.; Kausar, A.; Ramzan, S.; Sayab, M.; Yeats, R. S.

    2012-12-01

    The 2005 Kashmir earthquake (Mw 7.6) is the only Himalayan earthquake to rupture the surface since the 15th to 16th century A.D. when >Mw 8.5 earthquakes ruptured the Himalayan Frontal thrust (HFT) in the central Himalaya. Megathrust-type earthquakes like these seem to relieve a majority of the accumulated interseismic strain and concentrate permanent strain across a narrow width at the deformation front (faults within the orogen appear to accommodate little strain). The 2005 within-plate rupture in Kashmir may be a clue that a different seismotectonic model applies to the northwest Himalaya where active deformation occurs on faults distributed more than 120 km across the orogen. An asymmetric anticline marks the deformation front in Kashmir where the HFT is inferred to be blind, though ~20 m-high escarpments suggest that unrecognized thrust fault(s) may reach the surface locally. Folded river terraces and dip data also suggest that this frontal fold contains a SW-dipping back thrust. In Pakistan the Salt Range thrust system (SRT) defines the thrust front. New mapping and preliminary OSL dates from deformed Holocene sediments exposed along the westernmost SRT reveal that the fault slips at 1-7 mm/yr and last ruptured within the last several thousand years. Within the orogenic wedge to the north of the deformation front, active shortening occurs along a system of surface-rupturing reverse faults, extending from the Balakot-Bagh fault (source of the 2005 Kashmir earthquake) to the Reasi fault (RF) in Indian Kashmir to the southeast. One strand of the RF displaces a 350 m-high, 80 ± 6 ka (preliminary OSL age) fluvial terrace, yielding a minimum shortening rate of 3-5 mm/yr. Trenches excavated across the RF nearby reveal a distinct angular unconformity that likely formed during a surface rupture ~4500 yrs BP. Farther north, three northeast-dipping reverse faults cut Quaternary terraces on the southwest side of the Kashmir Valley. Trenches expose evidence for at least

  14. New Constraints on the Geometry and Kinematics of Active Faults in the Hinterland of the Northwest Himalaya

    NASA Astrophysics Data System (ADS)

    Morell, K. D.; Sandiford, M.; Rajendran, C. C. P.; Fink, D.; Kohn, B. P.

    2014-12-01

    The geometry and kinematics of the active, and potentially seismogenic, fault structures within the hinterland of the Himalaya have proven challenging to constrain in the past, primarily because active faults in this region tend to be buried beneath the subsurface and active seismicity often does not align with surficially mapped fault traces. Here we present a series of complementary datasets, including results from low temperature thermochronology, basin-wide erosion rates from 10Be concentrations, and topographic and longitudinal profile analyses, that place constraints on the spatial distribution of fault-related rock uplift and erosion across a ~400-km long region of the lower and high Himalaya of northwest India. Results from our analyses reveal that hillslope morphology and channel steepness are relatively invariant parallel to strike but vary significantly across strike, with the most prominent and abrupt variations occurring at the physiographic transition between the lower and high Himalaya (PT2), near the axial trace of the ramp-flat transition in the Main Himalayan Thrust (MHT). The cross-strike changes in geomorphology observed across the PT2 correlate with an order of magnitude northward increase in basin-wide erosion rates (~0.06-0.8 mm/a) and a corresponding decrease in apatite (~5-2 Ma) and zircon (U-Th)/He (~10-2 Ma) cooling ages. Combined with published geophysical and seismicity data, we interpret these results to reflect spatial variations in rock uplift and exhumation induced by a segment of the MHT ramp-flat system that is at least ~400 km long and ~125 km wide. The relatively young (U-Th)/He ages (<10 Ma) greater than 20 km south of the MHT ramp-flat transition preliminarily suggest that the kinematics of this system are best explained by a model which incorporates an accreting duplex on the MHT ramp but additional forthcoming analyses, including thermal modeling, will confirm if this hypothesis is robust.

  15. Active faulting induced by the slip partitioning in the Lesser Antilles arc

    NASA Astrophysics Data System (ADS)

    Leclerc, Frédérique; Feuillet, Nathalie

    2010-05-01

    AGUADOMAR marine cruise data acquired 11 years ago allowed us to identified and map two main sets of active faults within the Lesser Antilles arc (Feuillet et al., 2002; 2004). The faults belonging to the first set, such as Morne-Piton in Guadeloupe, bound up to 100km-long and 50km-wide arc-perpendicular graben or half graben that disrupt the fore-arc reef platforms. The faults of the second set form right-stepping en echelon arrays, accommodating left-lateral slip along the inner, volcanic islands. The two fault systems form a sinistral horsetail east of the tip of the left-lateral Puerto Rico fault zone that takes up the trench-parallel component of convergence between the North-American and Caribbean plates west of the Anegada passage. In other words, they together accommodate large-scale slip partitioning along the northeastern arc, consistent with recent GPS measurements (Lopez et al., 2006). These intraplate faults are responsible for a part of the shallow seismicity in the arc and have produce damaging historical earthquakes. Two magnitude 6.3 events occurred in the last 25 years along the inner en echelon faults, the last one on November 21 2004 in Les Saintes in the Guadeloupe archipelago. To better constrain the seismic hazard related to the inner arc faults and image the ruptures and effects on the seafloor of Les Saintes 2004 earthquake, we acquired new marine data between 23 February and 25 March 2009 aboard the French R/V le Suroît during the GWADASEIS cruise. We present here the data (high-resolution 72 channel and very high-resolution chirp 3.5 khz seismic reflection profiles, EM300 multibeam bathymetry, Küllenberg coring and SAR imagery) and the first results. We identified, mapped and characterized in detail several normal to oblique fault systems between Martinique and Saba. They offset the seafloor by several hundred meters and crosscut all active volcanoes, among them Nevis Peak, Soufriere Hills, Soufriere de Guadeloupe and Montagne Pel

  16. GPS-derived slip rates of active faults in eastern Venezuela, along the southeastern Caribbean PBZ

    NASA Astrophysics Data System (ADS)

    Audemard, F. A.; Beck, C.; Jouanne, F.; Reinoza, C. E.; Fegag

    2013-05-01

    For over 20 years, GPS campaign measurements have been performed in eastern Venezuela, as well as in other areas of the country, by different scientific groups and in the frame of different either national or international efforts and/or projects, essentially aiming at the estimation of the rate of motion along the major Quaternary faults (i.e., Boconó, San Sebastián and El Pilar faults) composing the plate boundary zone (PBZ) between the Caribbean and South America, along onshore northern and western Venezuela. The slip rates and sense of slip of those major faults derived from the comparison of several GPS campaigns carried out through the years have confirmed the slip data (fault kinematics) previously derived from geologic data, through comprehensive neotectonic and paleoseismic studies mainly made by the FUNVISIS' Earth Sciences Dpt. staff. In a rough way, we could conclude that those faults are dextrally moving at a rate in the order of 10-12 mm/a. More recently, it has been shown that the El Pilar fault has a locking depth close to 10 km deep and that about half of the PBZ dextral motion is accommodated as creep, reducing the seismic hazard for northeastern Venezuela almost by half. On the contrary, in the near past, very little attention has been paid to the secondary active faulting in eastern Venezuela. In that sense, FUNVISIS, in collaboration with the Université de Savoie, started the monitoring of these secondary features by installing 36 brass benchmarks on bedrock in that region in 2003, which have been occupied 3 times, in late 2003 and 2005 and in early 2013. The comparison between the 2003 and 2005 occupations shows promising results, such as: a) The Charagato fault on Cubagua island is left-lateral with a slip rate of about 2 mm/a; b) slip vectors across the El Pilar fault tend to head to the ESE, suggesting that the tectonic regime is compressive transcurrent to transcurrent compressional (transpressional); c) The NW-SE-trending San Francisco

  17. Hidden faults in the Gobi Desert (Inner Mongolia, China) - evidence for fault activity in a previously tectonically stable zone

    NASA Astrophysics Data System (ADS)

    Rudersdorf, Andreas; Haedke, Hanna; Reicherter, Klaus

    2013-04-01

    The Gaxun Nur Basin (GNB, also Ejina Basin, Hei River Basin, Ruoshui Basin) north of the Tibetan Plateau and the Hexi Corridor is an endorheic basin bounded by the Bei Shan ranges in the west, the Gobi Altai mountains in the north and the Badain Jaran sand desert in the east. The basin is fed from the south by the braided drainage system of the Hei He (Hei River) and its tributaries, which originate in the Qilian Shan; terminal lakes like the dried Gaxun Nur and Sogo Nur are and have been temporal. The sedimentary succession of up to 300 m comprises intercalations of not only alluvial deposits but also lake sediments and playa evaporites. The basin has been regarded as tectonically inactive by earlier authors; however, the dating of sediments from an earlier drill core in the basin center provided some implications for tectonic activity. Subsequent remote sensing efforts revealed large lineaments throughout the basin which are now considered as possible fault line fingerprints. We investigated well preserved Yardangs (clay terraces) in the northeastern part of the GNB, in the vicinity of the Juyanze (paleo) lake, and found evidence for Holocene active tectonics (seismites). We present a lithological analysis of the relevant sequences and conclusions on the recent tectonic activity within the study area.

  18. Identification of active faults in Abruzzo area (central Italy) through the analysis of geological, seismological and gravimetric data

    NASA Astrophysics Data System (ADS)

    Luiso, Paola; Paoletti, Valeria; Gaudiosi, Germana; Nappi, Rosa; Cella, Federico; Fedi, Maurizio

    2016-04-01

    Identification of active faults in abruzzo area (central italy) through the analysis of geological, seismological and gravimetric data The aim of this study is to identify and constrain the geometry of the seismogenic structures (active, outcropping and buried fault systems) of the Abruzzo area (central Italy), through an integrated analysis of geo-structural, seismic and gravimetric data. We generated three thematic: "faults", "earthquakes" and "gravimetric" data: i) The fault dataset consists of data extracted from the available structural and geological maps (ITHACA catalogue; the "Neotectonic Map of Italy" 1:500.000; several geological sheets 1:50.000 from ISPRA CARG project; the Geological Map 1:100.000 Sheet 1), and many geological studies. ii) The earthquakes datasets was created by merging the data from historical and instrumental Catalogues (CPTI04 and CPTI11; ISIDE - INGV). iii) The gravimetric datasets consists in the Multiscale Derivative Analysis (MDA) of the Bouguer anomaly map of the area, whose maxima show the presence of density lineaments. The merge of these datasets in GIS environment, highlighted four possible scenarios of correlation between faults, earthquakes and MDA maxima: 1) the existence of active faults, revealed by a strong correlation between epicentral location of seismic clusters, fault positions and MDA maxima; 2) the existence of buried active faults, highlighted by a good correlation between MDA maxima and epicentral positions, without correspondence with faults known from geological data; 3) the existence of inactive or silent faults, detected by the presence of faults reported in the geological datasets and literature which are associated with MDA maxima, without correlation of earthquakes; 4) the existence of faults not correlated with MDA maxima; this could be due to faults putting in contact two lithologies with a similar density. A comparison between seismic hypocentral locations and the fault geometry retrieved by DEXP

  19. The Nisi Fault as a key structure for understanding the active deformation of the NW Peloponnese, Greece

    NASA Astrophysics Data System (ADS)

    Zygouri, V.; Koukouvelas, I. K.; Kokkalas, S.; Xypolias, P.; Papadopoulos, G. A.

    2015-05-01

    The previously unknown Nisi Fault in NW Peloponnese was ruptured during the 2008 Movri Mountain earthquake attaining a maximum offset of 25 cm. The fault is interpreted as a branch of a flower structure above a blind strike-slip fault. We investigate the Nisi Fault seismotectonic evolution using morphotectonic analysis in order to determine whether the landscape is affected by tectonic forcing and paleoseismology to determine earthquake recurrence interval and fault slip rates. We applied several geomorphic indices, such as the asymmetry factor (AF), the stream length-gradient index (SL), the valley floor width to valley height ratio (Vf), the mountain-front sinuosity (Smf), the drainage basin shape (Bs) and the hypsometric curve (Hc), in four large drainage basins of the study area. The results show that fault-related vertical motions and the associated tilting influenced the drainage geometry and the landscape development. Values of stream-gradient indices (SL) are relatively high close to the fault trace. Mountain-front sinuosity (Smf) mean values along the fault zones range from 1.12 to 1.23. Valley floor width to valley height ratios (Vf) mean values along the studied fault range between 0.21 and 2.50. Drainage basin shape (BS) mean values along the fault range from 1.04 to 3.72. Lateral fault growth was likely achieved by propagation primarily towards north-northwestward. The paleoseismic history of the fault, investigated by a trench and 14C dating of seven samples, indicates two morphogenic earthquakes in the last 1 kyr. Therefore, we suggest that the Nisi Fault displays a slip rate on the order of 1 mm/yr and a recurrence interval ranging between 300 and 600 years. From a seismotectonic point of view, the fault is classified as high activity rate, with abundant but discontinuous geomorphic evidence of its activity. Other similar faults affecting the western Peloponnese can be envisaged with a similar procedure. Additionally, the seismic history and surface

  20. Definition and Paleoseismology of the Active, Left-Lateral Enriquillo-Plantain Garden Fault Zone Based on High-Resolution Chirp Profiles: Lakes Azuey and Mirogoane, Haiti

    NASA Astrophysics Data System (ADS)

    Wang, J.; Mann, P.; von Lignau, A. V.

    2014-12-01

    In July 2014, we obtained a total of 94 km of high-resolution Chirp profiles from the 129 km2, brackish Lake Azuey and 37 km of profiles from the 14 km2, fresh water Lake Mirogoane that both straddle the active trace of the Enriquillo-Plantain Garden fault zone (EPGFZ) of Haiti. 80% of the grid on Azuey and 85% on Mirogoane was dedicated to north-south profiles of the EPGFZ. In Azuey we defined the linear and east-west-striking fault trace in deformed Holocene sediments along with its landfalls west of Lake Azuey in Haiti and east of Lake Azuey in the Dominican Republic. All profiles showed the fault to be a sub-vertical flower structure whose active traces could be traced on Chirp data to a depth of 30 m below the lake floor. Previous workers have suggested that this fault ruptured during a large November, 1751, earthquake with a parallel and elongate felt zone. We hypothesize the most recent break of the fault several meters below the lake floor to have formed during the 1751 event but plan a coring program to precisely constrain the timing of historical and prehistorical events based on syn-faulting colluvial wedges observed on Chirp profiles. Our survey of Mirogoane confirmed its rhomboidal pull-apart structure with the basin center at a depth of 42-8 m making this basin the deepest lake in the Caribbean region. Deformational features include active folds at the lake bottom, large oblique-slip normal faults at an angle to the bounding east-west faults, and 30 m of recognizable stratigraphy. The 7 m of Holocene cored in the basin center in 1988 is observed to be highly deformed and locally folded and overlies with angular unconformity a well stratified and more folded lower basinal unit. Historical events are proposed to have ruptured on or near this segment of the EPGFZ in 1701 and 1770.

  1. Insights into the 3D architecture of an active caldera ring-fault at Tendürek volcano through modeling of geodetic data

    NASA Astrophysics Data System (ADS)

    Bathke, H.; Nikkhoo, M.; Holohan, E. P.; Walter, T. R.

    2015-07-01

    The three-dimensional assessment of ring-fault geometries and kinematics at active caldera volcanoes is typically limited by sparse field, geodetic or seismological data, or by only partial ring-fault rupture or slip. Here we use a novel combination of spatially dense InSAR time-series data, numerical models and sand-box experiments to determine the three-dimensional geometry and kinematics of a sub-surface ring-fault at Tendürek volcano in Turkey. The InSAR data reveal that the area within the ring-fault not only subsides, but also shows substantial westward-directed lateral movement. The models and experiments explain this as a consequence of a 'sliding-trapdoor' ring-fault architecture that is mostly composed of outward-inclined reverse segments, most markedly so on the volcano's western flanks but includes inward-inclined normal segments on its eastern flanks. Furthermore, the model ring-fault exhibits dextral and sinistral strike-slip components that are roughly bilaterally distributed onto its northern and southern segments, respectively. Our more complex numerical model describes the deformation at Tendürek better than an analytical solution for a single rectangular dislocation in a half-space. Comparison to ring-faults defined at Glen Coe, Fernandina and Bárðarbunga calderas suggests that 'sliding-trapdoor' ring-fault geometries may be common in nature and should therefore be considered in geological and geophysical interpretations of ring-faults at different scales worldwide.

  2. Active faulting in low- to moderate-seismicity regions: the SAFE project

    NASA Astrophysics Data System (ADS)

    Sebrier, M.; Safe Consortium

    2003-04-01

    SAFE (Slow Active Faults in Europe) is an EC-FP5 funded multidisciplinary effort which proposes an integrated European approach in identifying and characterizing active faults as input for evaluating seismic hazard in low- to moderate-seismicity regions. Seismically active western European regions are generally characterized by low hazard but high risk, due to the concentration of human and material properties with high vulnerability. Detecting, and then analysing, tectonic deformations that may lead to destructive earthquakes in such areas has to take into account three major limitations: - the typical climate of western Europe (heavy vegetation cover and/or erosion) ; - the subdued geomorphic signature of slowly deforming faults ; - the heavy modification of landscape by human activity. The main objective of SAFE, i.e., improving the assessment of seismic hazard through understanding of the mechanics and recurrence of active faults in slowly deforming regions, is achieved through four major steps : (1) extending geologic and geomorphic investigations of fault activity beyond the Holocene to take into account various time-windows; (2) developing an expert system that combines diverse lines of geologic, seismologic, geomorphic, and geophysical evidence to diagnose the existence and seismogenic potential of slow active faults; (3) delineating and characterising high seismic risk areas of western Europe, either from historical or geological/geomorphic evidence; (4) demonstrating and discussing the impact of the project results on risk assessment through a seismic scenario in the Basel-Mulhouse pilot area. To take properly into account known differences in source behavior, these goals are pursued both in extensional (Lower and Upper Rhine Graben, Catalan Coast) and compressional tectonic settings (southern Upper Rhine Graben, Po Plain, and Provence). Two arid compressional regions (SE Spain and Moroccan High Atlas) have also been selected to address the limitations

  3. Origin, Behavior and Texture of Clay Minerals in Mongolian Active Fault of Bogd and Comparison with SAFOD Fault Gouge

    NASA Astrophysics Data System (ADS)

    Wenk, H.; Buatier, M.; Chauvet, A.; Kanitpanyacharoen, W.

    2010-12-01

    Fault gouges are generally considered as the highly deformed zone corresponding to the localization of shear during seismic events. Clays are ubiquitous minerals in fault gouges but the origin is unclear. They can form as a result of break up of inherited phyllosilicates during faulting, or during co- or post- deformation events or even during interseismic creeping. In this study, we aim to characterize the origin and nature of the clay minerals, to observe the microtexture and preferred orientation of clay at various scales in order to understand the behavior of clay mineral in seismic faults. The investigation relied on x-ray powder patterns, SEM, TEM and high energy synchrotron x-ray diffraction. The major clay components are smectite, illite-smectite, illite-mica and kaolinite. Our observations suggest that the protolith and the fault rock of the Bogd and paleo-Bogd faults in Mongolia were highly altered by fluids. The fluid-rock interactions allows clay minerals to form and to precipitate kaolinite and smectite. Thus, newly formed clay minerals are heterogeneously distributed in the fault zone. The decrease of smectite component of the highly deformed samples suggests a dehydration process during deformation, leading to illite precipitation. From synchrotron diffraction images, volume fractions and preferred orientation were analyzed. Our analysis shows that texture strength of constituent clays is very weak ranging from 1.05 to 2.59 m.r.d., which is consistent with similar data from SAFOD fault gouge. The clays minerals of the Bogd fault favors the slip weakening behavior of the fault.

  4. Modeling crustal deformation near active faults and volcanic centers: a catalog of deformation models and modeling approaches

    USGS Publications Warehouse

    Battaglia, Maurizio; ,; Peter, F.; Murray, Jessica R.

    2013-01-01

    This manual provides the physical and mathematical concepts for selected models used to interpret deformation measurements near active faults and volcanic centers. The emphasis is on analytical models of deformation that can be compared with data from the Global Positioning System (GPS) receivers, Interferometric synthetic aperture radar (InSAR), leveling surveys, tiltmeters and strainmeters. Source models include pressurized spherical, ellipsoidal, and horizontal penny-shaped geometries in an elastic, homogeneous, flat half-space. Vertical dikes and faults are described following the mathematical notation for rectangular dislocations in an elastic, homogeneous, flat half-space. All the analytical expressions were verified against numerical models developed by use of COMSOL Multyphics, a Finite Element Analysis software (http://www.comsol.com). In this way, typographical errors present were identified and corrected. Matlab scripts are also provided to facilitate the application of these models.

  5. Evidence of sub Kilometer-scale Variability in Stress Directions near Active Faults: An Example from the Newport-Inglewood Fault, Southern California

    NASA Astrophysics Data System (ADS)

    Persaud, P.; Stock, J. M.; Smith, D.

    2015-12-01

    The active Newport-Inglewood Fault (NIF) zone is a series of right-lateral, left-stepping en echelon segments and associated anticlines that produced the 1933 Long Beach Mw 6.4 earthquake. Seismic hazard estimates, dynamic earthquake rupture models, and earthquake simulations for Southern California rely on information on the stress field obtained from the Community Stress Model (CSM), though the latter still lacks observational constraints. This study provides much needed observational constraints on in-situ stress, which are useful for validating the CSM. Our results highlight the possibility of variations in stress directions near active faults at length-scales less than 1 km. We determined the orientation of stress-induced compressive failures or borehole breakouts, which are reliable indicators of the orientation of the maximum horizontal stress (SH) in over 40 wellbores in the Los Angeles basin near the NIF. The compressional jogs along the fault have long been drilled for oil in this major metropolitan area, and so provide the dataset of oriented caliper logs. This allowed us to investigate the variation of SH direction in three oil fields. In the Inglewood oil field, a dense dataset of 24 wells in ~2 km2, SH varies from N9°E to N32°E over a depth range of 1-3 km and within 400 m of the fault in the western fault block, with more variability occurring in wells father away. At depths below 2 km, SH takes on a more northerly orientation. In contrast, SH is oriented E-W in the eastern fault block, based on constraints from two wells. In the Wilmington oil field located between the Thums-Huntington Beach Fault and the NIF, data from 11 deviated wells yields a pattern of elongation directions, which differs from the more complex pattern obtained for the Huntington Beach wells located ~12 km to the southeast. The short-length-scale variations in SH direction are attributed to the proximity to faults or fault segmentation, and indicate the likely complexity that

  6. Fault Branching

    NASA Astrophysics Data System (ADS)

    Dmowska, R.; Rice, J. R.; Poliakov, A. N.

    2001-12-01

    Theoretical stress analysis for a propagating shear rupture suggests that the propensity of the rupture path to branch is determined by rupture speed and by the preexisting stress state. See Poliakov, Dmowska and Rice (JGR, submitted April 2001, URL below). Deviatoric stresses near a mode II rupture tip are found to be much higher to both sides of the fault plane than directly ahead, when rupture speed becomes close to the Rayleigh speed. However, the actual pattern of predicted Coulomb failure on secondary faults is strongly dependent on the angle between the fault and the direction of maximum compression Smax in the pre-stress field. Steep Smax angles lead to more extensive failure on the extensional side, whereas shallow angles give comparable failure regions on both. Here we test such concepts against natural examples. For crustal thrust faults we may assume that Smax is horizontal. Thus nucleation on a steeply dipping plane, like the 53 ° dip for the 1971 San Fernando earthquake, is consistent with rupture path kinking to the extensional side, as inferred. Nucleation on a shallow dip, like for the 12 ° -18 ° of the 1985 Kettleman Hills event, should activate both sides, as seems consistent with aftershock patterns. Similarly, in a strike slip example, Smax is inferred to be at approximately 60 ° with the Johnson Valley fault where it branched to the extensional side onto the Landers-Kickapoo fault in the 1992 event, and this too is consistent. Further, geological examination of the activation of secondary fault features along the Johnson Valley fault and the Homestead Valley fault consistently shows that most activity occurs on the extensional side. Another strike-slip example is the Imperial Valley 1979 earthquake. The approximate Smax direction is north-south, at around 35 ° with the main fault, where it branched, on the extensional side, onto Brawley fault, again interpretable with the concepts developed.

  7. Monte Carlo simulation of peak-acceleration attenuation using a finite-fault uniform-patch model including isochrone and extremal characteristics

    USGS Publications Warehouse

    Rogers, A.M.; Perkins, D.M.

    1996-01-01

    A finite-fault statistical model of the earthquake source is used to confirm observed magnitude and distance saturation scaling in a large peak-acceleration data set. This model allows us to determine the form of peak-acceleration attenuation curves without a priori assumptions about their shape or scaling properties. The source is composed of patches having uniform size and statistical properties. The primary source parameters are the patch peak-acceleration distribution mean, the distribution standard deviation, the patch size, and patch-rupture duration. Although our model assumes no scaling of peak acceleration with magnitude at the patch, the peak-acceleration attenuation curves, nevertheless, strongly scale with magnitude (dap/dM) ??? 0, and the scaling is distance dependent (dap/dM) ??? f(r). The distance-dependent magnitude scaling arises from two principal sources in the model. For a propagating rupture, loci exist on the fault from which radiated energy arrives at a particular station at the same time. These loci are referred to as isochrones. As fault size increases, the length of the isochrones and, hence, the number of additive pulses increase. Thus, peak accelerations increase with magnitude. The second effect, which arises in a completely different manner, is due to extreme-value properties. That is, as the fault size increases, the number of patches on the fault and the number of peak values at the station increase. Because these attenuated pulses are produced by a statistical distribution at the patch, the largest value will depend on the total number of peak values available on the seismogram. We refer to this result as the extremal effect, because it is predicted by the theory of extreme values. Both the extremal and isochrone effects are moderated by attenuation and distance to the fault, leading to magnitude- and distance-dependent peak-acceleration scaling. Remarkably, the scaling produced by both effects is very similar, although the

  8. Assessing low-activity faults for the seismic safety of dams

    SciTech Connect

    Page, W.D.; Savage, W.U.; McLaren, M.K.

    1995-12-31

    Dams have been a familiar construct in the northern Sierra Nevada range in California (north of the San Joaquin River) since the forty-niners and farmers diverted water to their gold mines and farms in the mid 19th century. Today, more than 370 dams dot the region from the Central Valley to the eastern escarpment. Fifty-five more dam streams on the eastern slope. The dams are of all types: 240 earth fill; 56 concrete gravity; 45 rock and earth fills; 35 rock fill; 14 concrete arch; 9 hydraulic fill; and 29 various other types. We use the northern Sierra Nevada to illustrate the assessment of low-activity faults for the seismic safety of dams. The approach, techniques, and methods of evaluation are applicable to other regions characterized by low seismicity and low-activity faults having long recurrence intervals. Even though several moderate earthquakes had shaken the Sierra Nevada since 1849 (for example, the 1875 magnitude 5.8 Honey Lake and the 1909 magnitudes 5 and 5.5 Downieville earthquakes), seismic analyses for dams in the area generally were not performed prior to the middle of this century. Following the 1971 magnitude 6.7 San Fernando earthquake, when the hydraulic-fill Lower Van Norman Dam in southern California narrowly escaped catastrophic failure, the California Division of Safety of Dams and the Federal Energy Regulatory Commission required seismic safety to be addressed with increasing rigor. In 1975, the magnitude 5.7 Oroville earthquake on the Cleveland Hill fault near Oroville Dam in the Sierra Nevada foothills, showed convincingly that earthquakes and surface faulting could occur within the range. Following this event, faults along the ancient Foothills fault system have been extensively investigated at dam sites.

  9. Establishment of Active Traces of Lower Tagus Valley Fault Zone through an Integrated Approach

    NASA Astrophysics Data System (ADS)

    Besana-Ostman, G. M.; Vilanova, S.; Flor, A.; Canora, C.; Heleno, S.; Domingues, A.; Narciso, J.; Pinheiro, P.; Pinto, L.; Fonseca, J. F.

    2013-05-01

    Despite the occurrence of at least two damaging earthquakes in historical times - the M~7 1531 and the M6 1909 earthquakes - the Lower Tagus Valley Fault Zone (LTVFZ) has only recently been mapped (Besana-Ostman et al., 2012). In addition, a new set of active traces has been identified to the east during recent analysis and field inspections. The major challenges to the identification of active traces within Lower Tagus Valley (LTV) are both the presence of the very dynamic Tagus River (LTR) and the extensive urban and agricultural modifications introduced in the landscape. The detailed reports on the geological effects of the 1909 earthquake, while documenting extensively the secondary, shaking-related effects, provide no indication of surface rupture. The active traces of the northeast-southwest trending left-lateral LTVFZ within the LTV were established through integrated approaches as follows: aerial photo analysis, drainage system and satellite images examination, geomorphic feature identification, field mapping, geomorphic index measurements and trenching. The mapped traces extend to about 80 kilometers long and transect Quaternary and Holocene deposits. The mapped length of the western splay is compatible with an M7.2 earthquake. On the other hand, the newly mapped eastern traces plot almost parallel with the western splay, which may extend southwards to a comparable length. Preliminary analysis of satellite data show some evidence of additional splays located further east and south relative to the LTV. The new active traces suggest that the LTVFZ is a left-stepping left-lateral fault system with a regional NNE-SSW trend. Moreover, its extent and kinematics suggest magnitudes higher than previously assessed for the region. The location of the active traces displays a better correlation with the damage distribution of the historical events. Given the significance and implications of these findings for earthquake hazards assessment in Portugal, further studies

  10. SAFE-Tools: a Web-based application for identifying active faults

    NASA Astrophysics Data System (ADS)

    Atakan, K.; Sebrier, M.; Camelbeeck, T.; Siame, L.; Valensise, G.; Winter, T.

    2003-04-01

    Recognition of active faults, particularly in low seismicity regions such as Western Europe, has been a subject puzzling seismologists for many years. These regions are generally characterized by low-hazard but high-risk, due to the concentration of human and material properties with high-vulnerability. Detecting tectonic deformations that may lead to destructive earthquakes in such areas requires innovative research strategies that suit climate, slowly deforming fault, and heavily human-modified areas. The variety and amount of information involved in the characterization of slowly deforming faults are in general disseminated in several institutions with no easy access to. This information should be gathered, parameterized and stored in a way that make them feasible to be used in seismic hazard studies. In this sense, within the framework of the European project SAFE (Slow Active Faults in Europe; EVG1-2000-22005) a Web-based application (SAFE-Tools) for diagnosing slow active faults is developed. The basic design of the SAFE-Tools (SAFE-T) is based on server-client architecture, with data communication and visualization occurring through the Internet. The system is developed using the Java programming language and operates through an Internet browser. SAFE-T handles both parametric and graphical (image) data with a display and manipulation capability of pre-prepared data sets from a relational database with an interactive processing capacity all conducted through applets. A distributed database structure is developed opening a possibility for a network of interconnected servers. Layers of graphical data (e.g. geological maps, DEM images etc.) and sets of parametric data (e.g. historical or instrumental earthquake catalogues) are entered to the system either through an interactive process using HTML-forms, or as a bulk entry. Data are stored as geographical co-ordinate points with different attributes in the relational database. For identification of active faults

  11. Heterogeneity in friction strength of an active fault by incorporation of fragments of the surrounding host rock

    NASA Astrophysics Data System (ADS)

    Kato, Naoki; Hirono, Tetsuro

    2016-07-01

    To understand the correlation between the mesoscale structure and the frictional strength of an active fault, we performed a field investigation of the Atera fault at Tase, central Japan, and made laboratory-based determinations of its mineral assemblages and friction coefficients. The fault zone contains a light gray fault gouge, a brown fault gouge, and a black fault breccia. Samples of the two gouges contained large amounts of clay minerals such as smectite and had low friction coefficients of approximately 0.2-0.4 under the condition of 0.01 m s-1 slip velocity and 0.5-2.5 MP confining pressure, whereas the breccia contained large amounts of angular quartz and feldspar and had a friction coefficient of 0.7 under the same condition. Because the fault breccia closely resembles the granitic rock of the hangingwall in composition, texture, and friction coefficient, we interpret the breccia as having originated from this protolith. If the mechanical incorporation of wall rocks of high friction coefficient into fault zones is widespread at the mesoscale, it causes the heterogeneity in friction strength of fault zones and might contribute to the evolution of fault-zone architectures.

  12. Late Pleistocene to Historical Activity of the Hovd Fault (Mongolian Altay) from Tectonic Geomorphology and Paleoseismology

    NASA Astrophysics Data System (ADS)

    Ferry, M. A.; Battogtokh, D.; Ritz, J. F.; Kurtz, R.; Braucher, R.; Klinger, Y.; Ulzibat, M.; Chimed, O.; Demberel, S.

    2015-12-01

    Active tectonics of western Mongolia is dominated by large strike-slip fault systems that produced great historical earthquakes: the Bulnay fault (Mw 8.1 and 8.4 in 1905), the Fu-Yun fault (Mw 8.0 in 1931) and the Bogd fault (Mw 8.1 in 1957). Central to these faults is the Altay Range that accommodates ~4 mm/yr of right-lateral motion. An earthquake of similar magnitude occurred in 1761 and has been attributed to the Hovd fault were seemingly fresh surface rupture was reported in 1985. Here, we study the Ar-Hötöl section of the Hovd fault where surface rupture was described over a length of ~200 km. Detailed mapping of stream gullies from high-resolution Pleiades satellite images show a consistent pattern of right-lateral offsets from a few meters to ~500 m. At Climbing Rock, we surveyed a gully offset by 75 ± 5 m. The associated surface was sampled for 10Be profile which yields an exposure age of 154 ± 20 ka. The resulting minimal right-lateral slip rate ranges 0.4-0.6 mm/yr. However, drainage reconstruction suggests this surface may have recorded as much as 400 ± 20 m of cumulative offset. This implies the Hovd fault may accommodate as much as 2.6 ± 0.4 mm/yr, which would make it the main active fault of the Altay. At a smaller scale, TLS topography documents offsets in the order of 2.5-5 m that likely correspond to the most recent surface-rupturing event with Mw ~8. A value of 2.8-3.0 m is reconstructed from a Uiger grave dated AD 750-840. At Marmot Creek and Small Creek, short drainages flow across the fault and form ponds against the main scarp. Two paleoseimic trenches reveal similar stratigraphy with numerous peat layers that developed over alluvial sands. The fault exhibits near vertical strands affecting pre-ponding units as well as a well-developed peat unit radiocarbon-dated AD 1465-1635. This unit likely corresponds to the ground surface at the time of the last rupture. It is overlain with a sandy pond unit on top of which a second continuous peat

  13. Constraining fault activity by investigating tectonically-deformed Quaternary palaeoshorelines using a synchronous correlation method: the Capo D'Orlando Fault as a case study (NE Sicily, Italy)

    NASA Astrophysics Data System (ADS)

    Meschis, Marco; Roberts, Gerald P.; Robertson, Jennifer

    2016-04-01

    Long-term curstal extension rates, accommodated by active normal faults, can be constrained by investigating Late Quaternary vertical movements. Sequences of marine terraces tectonically deformed by active faults mark the interaction between tectonic activity, sea-level changes and active faulting throughout the Quaternary (e.g. Armijo et al., 1996, Giunta et al, 2011, Roberts et al., 2013). Crustal deformation can be calculated over multiple seismic cycles by mapping Quaternary tectonically-deformed palaeoshorelines, both in the hangingwall and footwall of active normal faults (Roberts et al., 2013). Here we use a synchronous correlation method between palaeoshorelines elevations and the ages of sea-level highstands (see Roberts et al., 2013 for further details) which takes advantage of the facts that (i) sea-level highstands are not evenly-spaced in time, yet must correlate with palaeoshorelines that are commonly not evenly-spaced in elevation, and (ii) that older terraces may be destroyed and/or overprinted by younger highstands, so that the next higher or lower paleoshoreline does not necessarily correlate with the next older or younger sea-level highstand. We investigated a flight of Late Quaternary marine terraces deformed by normal faulting as a result of the Capo D'Orlando Fault in NE Sicily (e.g. Giunta et al., 2011). This fault lies within the Calabrian Arc which has experienced damaging seismic events such as the 1908 Messina Straits earthquake ~ Mw 7. Our mapping and previous mapping (Giunta et al. (2011) demonstrate that the elevations of marine terraces inner edges change along the strike the NE - SW oriented normal fault. This confirms active deformation on the Capo D'Orlando Fault, strongly suggesting that it should be added into the Database of Individual Seismogenic Sources (DISS, Basili et al., 2008). Giunta et al. (2011) suggested that uplift rates and hence faults lip-rates vary through time for this examples. We update the ages assigned to

  14. GeoBioScience: Red Wood Ants as Bioindicators for Active Tectonic Fault Systems in the West Eifel (Germany)

    PubMed Central

    Berberich, Gabriele; Schreiber, Ulrich

    2013-01-01

    Simple Summary In a 1.140 km² study area of the volcanic West Eifel, approx. 3,000 Red Wood Ant (RWA; Formica rufa-group) mounds had been identified and correlated with tectonically active gas-permeable faults, mostly strike-slip faults. Linear alignment of RWA mounds and soil gas anomalies distinctly indicate the course of these faults, while clusters of mounds indicate crosscut zones of fault systems, which can be correlated with voids caused by crustal block rotation. This demonstrates that RWA are bioindicators for identifying active fault systems and useful where information on the active regime is incomplete or the resolution by technical means is insufficient. Abstract In a 1.140 km² study area of the volcanic West Eifel, a comprehensive investigation established the correlation between red wood ant mound (RWA; Formica rufa-group) sites and active tectonic faults. The current stress field with a NW-SE-trending main stress direction opens pathways for geogenic gases and potential magmas following the same orientation. At the same time, Variscan and Mesozoic fault zones are reactivated. The results showed linear alignments and clusters of approx. 3,000 RWA mounds. While linear mound distribution correlate with strike-slip fault systems documented by quartz and ore veins and fault planes with slickensides, the clusters represent crosscut zones of dominant fault systems. Latter can be correlated with voids caused by crustal block rotation. Gas analyses from soil air, mineral springs and mofettes (CO2, Helium, Radon and H2S) reveal limiting concentrations for the spatial distribution of mounds and colonization. Striking is further the almost complete absence of RWA mounds in the core area of the Quaternary volcanic field. A possible cause can be found in occasionally occurring H2S in the fault systems, which is toxic at miniscule concentrations to the ants. Viewed overall, there is a strong relationship between RWA mounds and active tectonics in the West Eifel

  15. Active faults and induced seismicity in the Val d'Agri area (Southern Apennines, Italy)

    NASA Astrophysics Data System (ADS)

    Valoroso, L.; Improta, L.; Chiaraluce, L.; Di Stefano, R.; Ferranti, L.; Govoni, A.; Chiarabba, C.

    2009-07-01

    The NW-SE trending Val d'Agri extensional basin is one of the regions in Italy with the highest seismogenic potential. Field data do not univocally define which of the fault systems bordering the basin on the two opposite sides is accommodating the active deformation. In this study, we detect and locate, by using an automatic picking procedure, almost 2000 low-magnitude earthquakes (-0.2 < ML < 2.7) recorded by a dense network during a 13-months-long seismic experiment. Events are mostly located along the southwestern flank of the basin. To the south, intense swarm-type microseismicity defines a major cluster ~5km wide from 1 to 5km depth. To the west, a clear alignment of events, characterized by normal faulting kinematics, defines a NE-dipping normal fault between 1 and 6km depth. The upward continuation of this structure, ~5km long, matches a mapped active normal fault recognized by field and palaeoseismological surveys. A temporal correlation found between the intense swarm-type microseismicity and the water level changes in the nearby artificial Pertusillo lake suggests that this seismicity is reservoir-induced.

  16. Synthetic earthquake catalogs simulating seismic activity in the Corynth Gulf, Greece, fault system

    NASA Astrophysics Data System (ADS)

    Console, R.; Carluccio, R.; Papadimitriou, E. E.; Karakostas, V. G.

    2014-12-01

    The characteristic earthquake hypothesis is the basis of time-dependent modeling of earthquake recurrence on major faults, using the renewal process methodology. However, the characteristic earthquake hypothesis is not strongly supported by observational data. Few fault segments have long historical or paleoseismic records of individually dated ruptures, and when data and parameter uncertainties are allowed for, the form of the recurrence-distribution is difficult to establish. This is the case, for instance, of the Corinth gulf fault system, for which documents about strong earthquakes exist for at least two thousand years, but they can be considered complete for magnitudes > 6.0 only for the latest 300 years, during which only few characteristic earthquakes are reported for single fault segments. The use of a physics-based earthquake simulator has allowed the production of catalogs lasting 100,000 years and containing more than 500,000 events of magnitudes > 4.0. The main features of our simulation algorithm are (1) the imposition of an average slip rate released by earthquakes to every single segment recognized in the investigated fault system, (2) the interaction between earthquake sources, (3) a self-organized earthquake magnitude distribution, and (4) the effect of minor earthquakes in redistributing stress. The application of our simulation algorithm to the Corinth gulf fault system has shown realistic features in time, space and magnitude behavior of the seismicity. These features include long-term periodicity of strong earthquakes, short-term clustering of both strong and smaller events, and a realistic earthquake magnitude distribution departing from the Gutenberg-Richter distribution in the higher magnitude range.

  17. Geomorphic evidence of active faults growth in the Norcia seismic area (central Apennines, Italy)

    NASA Astrophysics Data System (ADS)

    Materazzi, Marco; Aringoli, Domenico; Farabollini, Piero; Giacopetti, Marco; Pambianchi, Gilberto; Tondi, Emanuele; Troiani, Francesco

    2016-04-01

    Fault-growth by segment linkage is one of the fundamental processes controlling the evolution, in both time and the space, of fault systems. In fact, step-like trajectories shown by length-displacement diagrams for individual fault arrays suggest that the development of evolved structures result by the linkage of single fault segments. The type of interaction between faults and the rate at which faults reactivate not only control the long term tectonic evolution of an area, but also influence the seismic hazard, as earthquake recurrence intervals tend to decrease as fault slip rate increase. The use of Geomorphological investigations represents an important tool to constrain the latest history of active faults. In this case, attention has to be given to recognize morphostructural, historical, environmental features at the surface, since they record the long-term seismic behavior due to the fault growth processes (Tondi and Cello, 2003). The aim of this work is to investigate the long term morphotectonic evolution of a well know seismic area in the central Apennines: the Norcia intramontane basin (Aringoli et al., 2005). The activity of the Norcia seismic area is characterized by moderate events and by strong earthquakes with maximum intensities of X-XI degrees MCS and equivalent magnitudes around 6.5±7.0 (CPTI, 2004). Based on the morphostructural features as well as on the historical seismicity of the area, we may divide the Norcia seismic area into three minor basins roughly NW-SE oriented: the Preci sub-basin in the north; the S. Scolastica and the Castel S. Maria sub-basins in the south. The wider basin (S. Scolastica) is separated from the other two by ridges transversally oriented with respect the basins themselves; they are the geomorphological response to the tectonic deformation which characterizes the whole area. Other geomorphological evidences of tectonic activity are represented by deformation of old summit erosional surfaces, hydrographic network

  18. An automatic continuous monitoring station for groundwater geochemistry at an active fault zone in SW Taiwan

    NASA Astrophysics Data System (ADS)

    Lai, Chun-Wei; Yang, Tsanyao F.; Fu, Ching-Chou; Hilton, David R.; Liu, Tsung-Kwei; Walia, Vivek; Lai, Tzu-Hua

    2015-04-01

    Previous studies have revealed that gas compositions of fluid samples collected from southwestern Taiwan where many hot springs and mud volcanoes are distributed along tectonic sutures show significant variation prior to and after some disaster seismic events. Such variations, including radon activity, CH4/CO2, CO2/3He and 3He/4He ratios of gas compositions, are considered to be precursors of earthquakes in this area. To validate the relationship between fluid compositions and local earthquakes, a continuous monitoring station has been established at Yun-Shui, which is an artesian well located at an active fault zone in SW Taiwan. It is equipped with a radon detector and a quadrupole mass spectrometer (QMS) for in-situ measurement of the dissolved gas composition. Data is telemetered to Taipei so we are able to monitor variations of gas composition in real time. Furthermore, we also installed a syringe pump apparatus for the retrieval and temporal analysis of helium (SPARTAH) at this station. From the SPARTAH samples, we can obtain detailed time series records of H-O isotopic compositions, DIC concentration and δ13C isotopic ratios, and anion concentration of the water samples at this station. After continuous monitoring for about one year, some anomalies occurred prior to some local earthquakes. It demonstrates that this automated system is feasible for long-term continuous seismo-geochemical research in this area. Keywords: monitoring; geochemistry; isotope; dissolved gases; pre-seismic signal.

  19. Information for Teachers (Including Classroom Activities), Skylab Student Project.

    ERIC Educational Resources Information Center

    National Aeronautics and Space Administration, Washington, DC.

    This program is intended to directly involve the educational community in space experiments, many of which can be related to existing curricula. Included in this first packet are: 1) a brief description of the Skylab Program and the National Science Teachers Association-National Aeronautics and Space Administration (NSTA-NASA) Skylab Student…

  20. Redefining Medlicott-Wadia's main boundary fault from Jhelum to Yamuna: An active fault strand of the main boundary thrust in northwest Himalaya

    NASA Astrophysics Data System (ADS)

    Thakur, V. C.; Jayangondaperumal, R.; Malik, M. A.

    2010-06-01

    The MBT demarcates a tectonic boundary between the Tertiary Sub Himalaya and the pre-Tertiary Lesser Himalaya. South of the MBT, another tectonically important fault extends from Muzaffarabad and Riasi in Jammu-Kashmir to Bilaspur and Nahan in Himachal. Medlicott and Wadia had designated this fault the Main Boundary Fault (MBF) in Simla Hills and Jammu region respectively. In between these two areas, later workers gave local-area names to the MBF as the Riasi Thrust in Jammu, Palampur Thrust in Kangra, Bilaspur Thrust in Simla Hills and Nahan Thrust in Sirmur. We have reviewed and established the tectonostratigraphic framework and physical continuity of the lower Tertiary belt and the MBF. The lower Tertiary belt, lying south of the MBT, has characteristic tectonostratigraphic setting with discontinuous bodies of stromatolite-bearing Proterozoic limestone overlain with depositional contact by the Paleocene-lower part Middle Eocene marine Subathu/Patala formation which in turn overlain by the Upper Oligocene-Lower Miocene non-marine Dharamsala/Murree Formation. To avoid confusion with the MBT, we designate collectively the MBF and related faults as the Medlicott-Wadia Thrust (MWT). The MWT extends east of Hazara-Kashmir syntaxis to river Yamuna, covering a distance of ˜ 700 km. Further east of Yamuna, the lower Tertiary belt pinches out and the MWT merges with the sensuo-stricto MBT. The Proterozoic limestone represents the basement over which the lower Tertiary sediments were deposited. The limestone basement with its cover was detached by the MWT, exhuming to the surface and thrusting over largely the Siwalik group. The reactivated Balakot-Bagh Fault, causative fault for the 2005 Kashmir earthquake, extends southeast with right-step to the Riasi Thrust. The Riasi Thrust shows evidence of reactivation and active tectonic activity in Jammu region. It extends further east to the Palampur Thrust in Kangra reentrant, which lies within the 1905 Kangra earthquake

  1. Sag-ponding and its Significance in determining Paleo-seismic events along the active strike- slip fault

    NASA Astrophysics Data System (ADS)

    Li, C.; Zhang, P.; Yuan, D.

    2007-12-01

    During the development of one active fault, we really want to know how it behaves and what it will do next. This mostly depends on the record and preservation of the information showing the action of the fault. Sparse young sediments or sediments with coarse grain along most of big strike-slip faults make it hard record and preserve the vestige of the paleo-seismic events. This extremely restricts the development of the Paleo-seismic research. Sag-ponding as well as the deposits in ponds, which are formed by the movement of the fault, can help settling the difficulty. Periodic sag-ponding is a feature to which should be paid more attention along the strike-slip fault, it can develop a pond to capture plenty fine sediments which well record the action of the faults. Sag-ponding can easily be found on the main active strike-slip faults in northern and eastern Tibet. By disclosing the sag-ponding depositions with 3-D excavations, sediment distribution and characters of relevant sag-ponds, and the relation between the sag-ponding and faulting were discussed. 1. Mechanism of the formation of the sag-pond When the valleys and ridges intersecting with the fault are displaced, the fault scarps will block the flow of the streams cut by the fault, or make the gullies develop ancon-like bend. This would form a space for water-storage, and thus a sag-pond comes into being. If the fault behaves like this many times, multi-sag-ponding will occur. 2. Rhythmic sag-ponding deposition features and stratigraphic sequence (1) Vertical characteristics. Observed from the stratigraphic profiles disclosed by the excavation, stratigraphic sequence shows good rhythms. There are several rhythms in each pond, and one rhythm is composed of the lower coarse layers and the upper fine layers. That is, the grains are coarser below and finer upward. (2) Transverse variation. In the direction parallel to the fault, the deposition center of each sag-pond appears regular movement, or migration

  2. Active Features of Guguan-Guizhen Fault at the Northeast Margin of Qinghai-Tibet Block since Late Quaternary

    NASA Astrophysics Data System (ADS)

    Shi, Yaqin; Feng, Xijie; Li, Gaoyang; Ma, Ji; Li, Miao; Zhang, Yi

    2015-04-01

    Guguan-Guizhen fault is located at the northeast margin of Qinghai-Tibet Block and northwest margin of Ordos Block; it is the boundary of the two blocks, and one of the multiple faults of northwest Haiyuan-Liupanshan-Baoji fault zone. Guguan-Guizhen fault starts from Putuo Village, Huating County, Gansu Province, and goes through Badu Town, Long County in Shaanxi Province ends in Guozhen Town in Baoji City, Shaanxi Province. The fault has a full length of about 130km with the strike of 310-330°, the dip of SW and the rake of 50-60°, which is a sinistral slip reverse fault in the north part, and a sinistral slip normal fault in the southeast part. Guguan-Guizhen fault has a clear liner structure in satellite images and significant landform elevation difference with a maximum difference of 80m, and is higher in the east lower in the west. The northwest side of Guguan-Guizhen fault is composed of purplish-red Lower Cretaceous sandstones and river terrace; the northeast side is composed of Ordovician Limestone. Shigou, Piliang, Songjiashan, Tianjiagou and Chenjiagou fault profiles are found to the south of Badu Village. After 14C and optically stimulated luminescence dating, the fault does not dislocate the stratum since late Pleistocene (90.5±4.4ka) in Shigou, Piliang and Songjiashan fault profiles, and does not dislocate the cobble layer of Holocene first terrace and recent sliderock (3180±30 BP). But the fault dislocated the stratum of middle Pleistocene in some of the fault profiles. All the evidences above indicate that the fault is active in middle Pleistocene, and being silence since late Pleistocene. It might be active in Holocene to the north of Badu Village due to collapses are found in a certain area. The cause of these collapses is Qinlong M6-7 earthquake in 600 A.D., and might be relevant with Guguan-Guizhen fault after analysis of the scale, feature and age determination of the collapse. If any seismic surface rupture and ancient earthquake traces

  3. Characterization of an active offshore coast-parallel fault system on the shallow SE continental shelf of New Zealand's South Island

    NASA Astrophysics Data System (ADS)

    Gorman, A. R.; Bruce, C.; Reid-Lindroos, Z.; Preskett, S.

    2009-12-01

    The Akatore Fault is an active reverse fault that is mapped along the SE coast of New Zealand’s South Island, south of Dunedin. It is the easternmost in a series of onshore faults resulting from the tectonic-inversion of a former range and basin system. This system of faults, lying within Pacific continental crust, extends across the ~250 km width of the South Island. It accommodates some of the motion resulting from the oblique collision of the Pacific and Australian plates, the boundary of which lies along the west coast of the South Island. The Akatore Fault runs onshore for about 25 km along a slight bulge in the coastline, and is inferred to continue just offshore to the NE and SW. Other coast-parallel faults have been proposed based on limited shallow seismic imaging of the shelf. Earthquakes in 1974 and 1989 with offshore epicenters were attributed to these faults. In February 2009, a detailed high-frequency seismic survey was undertaken over the northernmost section of the offshore Akatore Fault. Data recorded included single-channel Chirp and electro-acoustic (boomer) sub-bottom imaging, and interferometric side scanning sonar (C3D). A grid of 31 lines was collected with line spacing of ~250 m. Lines ran from just outside the surf zone to ~4 km offshore in water depths from ~10 to 60 m. Chirp and boomer data image the upper 5 to 60 m of sub-seafloor sediments and sedimentary rocks. Most of the shelf has little Quaternary cover in this region. Seismic lines are characterized by distinct, continuous, southeast-dipping reflections that correlate to the late Cretaceous - Tertiary sedimentary sequences that outcrop onshore. The boomer dataset recorded in this region has remarkably good penetration, often limited only by the occurrence of seafloor multiples. In a few locations, more rugged seafloor outcrops lead to poor penetration. These outcrops may consist of metamorphic basement rocks, volcanic extrusions, eroded igneous intrusions, or organic communities

  4. Medicare program; right of appeal for Medicare secondary payer determinations relating to liability insurance (including self-insurance), no-fault insurance, and workers' compensation laws and plans. Final rule.

    PubMed

    2015-02-27

    This final rule implements provisions of the Strengthening Medicare and Repaying Taxpayers Act of 2012 (SMART Act) which require us to provide a right of appeal and an appeal process for liability insurance (including self-insurance), no-fault insurance, and workers' compensation laws or plans when Medicare pursues a Medicare Secondary Payer (MSP) recovery claim directly from the liability insurance (including self-insurance), no-fault insurance, or workers' compensation law or plan.

  5. Fault Diagnosis Based on Chemical Sensor Data with an Active Deep Neural Network.

    PubMed

    Jiang, Peng; Hu, Zhixin; Liu, Jun; Yu, Shanen; Wu, Feng

    2016-10-13

    Big sensor data provide significant potential for chemical fault diagnosis, which involves the baseline values of security, stability and reliability in chemical processes. A deep neural network (DNN) with novel active learning for inducing chemical fault diagnosis is presented in this study. It is a method using large amount of chemical sensor data, which is a combination of deep learning and active learning criterion to target the difficulty of consecutive fault diagnosis. DNN with deep architectures, instead of shallow ones, could be developed through deep learning to learn a suitable feature representation from raw sensor data in an unsupervised manner using stacked denoising auto-encoder (SDAE) and work through a layer-by-layer successive learning process. The features are added to the top Softmax regression layer to construct the discriminative fault characteristics for diagnosis in a supervised manner. Considering the expensive and time consuming labeling of sensor data in chemical applications, in contrast to the available methods, we employ a novel active learning criterion for the particularity of chemical processes, which is a combination of Best vs. Second Best criterion (BvSB) and a Lowest False Positive criterion (LFP), for further fine-tuning of diagnosis model in an active manner rather than passive manner. That is, we allow models to rank the most informative sensor data to be labeled for updating the DNN parameters during the interaction phase. The effectiveness of the proposed method is validated in two well-known industrial datasets. Results indicate that the proposed method can obtain superior diagnosis accuracy and provide significant performance improvement in accuracy and false positive rate with less labeled chemical sensor data by further active learning compared with existing methods.

  6. Fault Diagnosis Based on Chemical Sensor Data with an Active Deep Neural Network

    PubMed Central

    Jiang, Peng; Hu, Zhixin; Liu, Jun; Yu, Shanen; Wu, Feng

    2016-01-01

    Big sensor data provide significant potential for chemical fault diagnosis, which involves the baseline values of security, stability and reliability in chemical processes. A deep neural network (DNN) with novel active learning for inducing chemical fault diagnosis is presented in this study. It is a method using large amount of chemical sensor data, which is a combination of deep learning and active learning criterion to target the difficulty of consecutive fault diagnosis. DNN with deep architectures, instead of shallow ones, could be developed through deep learning to learn a suitable feature representation from raw sensor data in an unsupervised manner using stacked denoising auto-encoder (SDAE) and work through a layer-by-layer successive learning process. The features are added to the top Softmax regression layer to construct the discriminative fault characteristics for diagnosis in a supervised manner. Considering the expensive and time consuming labeling of sensor data in chemical applications, in contrast to the available methods, we employ a novel active learning criterion for the particularity of chemical processes, which is a combination of Best vs. Second Best criterion (BvSB) and a Lowest False Positive criterion (LFP), for further fine-tuning of diagnosis model in an active manner rather than passive manner. That is, we allow models to rank the most informative sensor data to be labeled for updating the DNN parameters during the interaction phase. The effectiveness of the proposed method is validated in two well-known industrial datasets. Results indicate that the proposed method can obtain superior diagnosis accuracy and provide significant performance improvement in accuracy and false positive rate with less labeled chemical sensor data by further active learning compared with existing methods. PMID:27754386

  7. Map showing recently active breaks along the San Andreas Fault between Pt. Delgada and Bolinas Bay, California

    USGS Publications Warehouse

    Brown, Robert D.; Wolfe, Edward W.

    1970-01-01

    This strip map is one of a series of maps showing recently active fault breaks along the San Andreas and other active faults in California. It is designed to inform persons who are concerned with land use near the fault of the location of those fault breaks that have moved recently. The lines on the map are lines of rupture and creep that can be identified by field evidence and that clearly affect the present surface of the land. Map users should keep in mind that these lines are intended primarily as guides to help locate the fault; the mapped lines are not necessarily shown with the precision demanded by some engineering or land utilization needs.

  8. Active faults on the eastern flank of Etna volcano (Italy) monitored through soil radon measurements

    NASA Astrophysics Data System (ADS)

    Neri, M.; Giammanco, S.; Ferrera, E.; Patanè, G.; Zanon, V.

    2012-04-01

    This study concerns measurements of radon and thoron emissions from soil carried out in 2004 on the unstable eastern flank of Mt. Etna, in a zone characterized by the presence of numerous seismogenic and aseismic faults. The statistical treatment of the geochemical data allowed recognizing anomaly thresholds for both parameters and producing distribution maps that highlighted a significant spatial correlation between soil gas anomalies and tectonic lineaments. In particular, the highest anomalies were found at the intersection between WNW-ESE and NW-SE -running faults. The seismic activity occurring in and around the study area during 2004 was analyzed, producing maps of hypocentral depth and released seismic energy. These maps revealed a progressive deepening of hypocenters from NW to SE, with the exception of a narrow zone in the central part of the area, with a roughly WNW-ESE direction. Also, the highest values of seismic energy were released during events in the southern and northwestern sectors of the area. Both radon and thoron anomalies were located in areas affected by relatively deep (5-10 km depth) seismic activity, while less evident correlation was found between soil gas anomalies and the released seismic energy. This study confirms that mapping the distribution of radon and thoron in soil gas can reveal hidden faults buried by recent soil cover or faults that are not clearly visible at the surface. The correlation between soil gas data and earthquake depth and intensity can give some hints on the source of gas and/or on fault dynamics. Lastly, an important spin-off of this study is the recognition of some areas where radon activity was so high (>50000 Bq/m3) that it may represent a potential hazard to the local population. In fact, radon is the leading cause of lung cancer after cigarette smoke for long exposures and, due to its molecular weight, it accumulates in underground rooms or in low ground, particularly where air circulation is low or absent

  9. Origin of active blind-thrust faults in the southern Inner California Borderlands

    NASA Astrophysics Data System (ADS)

    Rivero-Ramirez, Carlos Alberto

    This dissertation describes the origins, three-dimensional geometry, slip history and present activity of a regional system of blind-thrust faults located in the Inner California Borderlands, and analyses the new earthquake scenarios they imply for the nearby coastal region of southern California. Chapter 1 is an overview of the main observations and inferences derived from geophysical data (seismic reflection profiles, well information, and seismicity) and coastal tectonics studies that are used to document the reactivation of two regional, low-angle Miocene detachments---the Oceanside and the Thirtymile faults. These active blind-thrusts comprise the Inner California Blind-Thrust System. The paper is co-authored by Prof. John H. Shaw (Harvard University) and Prof. Karl Muller (University of Colorado), and was published in the journal Geology. In this paper we associate the 1986 (ML 5.3) Oceanside earthquake and uplift of coastal marine terraces with activity on these blind-thrust faults, demonstrating their current activity and earthquake potential. We also describe the structural interactions of the blind-thrust system with regional strike-slip fault zones, and propose new earthquake hazards scenarios for the Inner California Borderlands based on these interactions. Chapter 2 presents a methodology used to generate regional 3D velocity models that allows converting seismic reflection data and derived geological surfaces into the depth domain. This chapter is co-authored with Dr. Peter Suss (University of Tubingen) and Prof. John H. Shaw (Harvard University), who developed aspects of the methodology used here in their velocity modeling of the Los Angeles basin. In our study, geologic constraints are employed to guide the interpolation of velocity structure in the Inner California Borderlands, yielding a comprehensive 3D velocity model that is consistent with the structural and stratigraphic architectures of the offshore basins. The need to properly scale time

  10. A Sensor Fault Detection Methodology applied to Piezoelectric Active Systems in Structural Health Monitoring Applications

    NASA Astrophysics Data System (ADS)

    Tibaduiza, D.; Anaya, M.; Forero, E.; Castro, R.; Pozo, F.

    2016-07-01

    Damage detection is the basis of the damage identification task in Structural Health Monitoring. A good damage detection process can ensure the adequate work of a SHM System because allows to know early information about the presence of a damage in a structure under evaluation. However this process is based on the premise that all sensors are well installed and they are working properly, however, it is not true all the time. Problems such as debonding, cuts and the use of the sensors under different environmental and operational conditions result in changes in the vibrational response and a bad functioning in the SHM system. As a contribution to evaluate the state of the sensors in a SHM system, this paper describes a methodology for sensor fault detection in a piezoelectric active system. The methodology involves the use of PCA for multivariate analysis and some damage indices as pattern recognition technique and is tested in a blade from a wind turbine where different scenarios are evaluated including sensor cuts and debonding.

  11. Active fault mapping in Karonga-Malawi after the December 19, 2009 Ms 6.2 seismic event

    NASA Astrophysics Data System (ADS)

    Macheyeki, A. S.; Mdala, H.; Chapola, L. S.; Manhiça, V. J.; Chisambi, J.; Feitio, P.; Ayele, A.; Barongo, J.; Ferdinand, R. W.; Ogubazghi, G.; Goitom, B.; Hlatywayo, J. D.; Kianji, G. K.; Marobhe, I.; Mulowezi, A.; Mutamina, D.; Mwano, J. M.; Shumba, B.; Tumwikirize, I.

    2015-02-01

    The East African Rift System (EARS) has natural hazards - earthquakes, volcanic eruptions, and landslides along the faulted margins, and in response to ground shaking. Strong damaging earthquakes have been occurring in the region along the EARS throughout historical time, example being the 7.4 (Ms) of December 1910. The most recent damaging earthquake is the Karonga earthquake in Malawi, which occurred on 19th December, 2009 with a magnitude of 6.2 (Ms). The earthquake claimed four lives and destroyed over 5000 houses. In its effort to improve seismic hazard assessment in the region, Eastern and Southern Africa Seismological Working Group (ESARSWG) under the sponsorship of the International Program on Physical Sciences (IPPS) carried out a study on active fault mapping in the region. The fieldwork employed geological and geophysical techniques. The geophysical techniques employed are ground magnetic, seismic refraction and resistivity surveys but are reported elsewhere. This article gives findings from geological techniques. The geological techniques aimed primarily at mapping of active faults in the area in order to delineate presence or absence of fault segments. Results show that the Karonga fault (the Karonga fault here referred to as the fault that ruptured to the surface following the 6th-19th December 2009 earthquake events in the Karonga area) is about 9 km long and dominated by dip slip faulting with dextral and insignificant sinistral components and it is made up of 3-4 segments of length 2-3 km. The segments are characterized by both left and right steps. Although field mapping show only 9 km of surface rupture, maximum vertical offset of about 43 cm imply that the surface rupture was in little excess of 14 km that corresponds with Mw = 6.4. We recommend the use or integration of multidisciplinary techniques in order to better understand the fault history, mechanism and other behavior of the fault/s for better urban planning in the area.

  12. Progressive failure during the 1596 Keicho earthquakes on the Median Tectonic Line active fault zone, southwest Japan

    NASA Astrophysics Data System (ADS)

    Ikeda, M.; Toda, S.; Nishizaka, N.; Onishi, K.; Suzuki, S.

    2015-12-01

    Rupture patterns of a long fault system are controlled by spatial heterogeneity of fault strength and stress associated with geometrical characteristics and stress perturbation history. Mechanical process for sequential ruptures and multiple simultaneous ruptures, one of the characteristics of a long fault such as the North Anatolian fault, governs the size and frequency of large earthquakes. Here we introduce one of the cases in southwest Japan and explore what controls rupture initiation, sequential ruptures and fault branching on a long fault system. The Median Tectonic Line active fault zone (hereinafter MTL) is the longest and most active fault in Japan. Based on historical accounts, a series of M ≥ 7 earthquakes occurred on at least a 300-km-long portion of the MTL in 1596. On September 1, the first event occurred on the Kawakami fault segment, in Central Shikoku, and the subsequent events occurred further west. Then on September 5, another rupture initiated from the Central to East Shikoku and then propagated toward the Rokko-Awaji fault zone to Kobe, a northern branch of the MTL, instead of the eastern main extent of the MTL. Another rupture eventually extended to near Kyoto. To reproduce this progressive failure, we applied two numerical models: one is a coulomb stress transfer; the other is a slip-tendency analysis under the tectonic stress. We found that Coulomb stress imparted from historical ruptures have triggered the subsequent ruptures nearby. However, stress transfer does not explain beginning of the sequence and rupture directivities. Instead, calculated slip-tendency values show highly variable along the MTL: high and low seismic potential in West and East Shikoku. The initiation point of the 1596 progressive failure locates near the boundary in the slip-tendency values. Furthermore, the slip-tendency on the Rokko-Awaji fault zone is far higher than that of the MTL in Wakayama, which may explain the rupture directivity toward Kobe-Kyoto.

  13. Identifying past earthquakes on an active normal fault (Magnola, Italy) from the chemical analysis of its exhumed carbonate fault plane

    NASA Astrophysics Data System (ADS)

    Carcaillet, Julien; Manighetti, Isabelle; Chauvel, Catherine; Schlagenhauf, Aloé; Nicole, Jean-Marc

    2008-07-01

    A normal fault scarp exhumed by repeated strong earthquakes is made of a series of rupture zones that were exposed, thus weathered, over significantly different time spans. We show that such differential weathering can be detected in the chemical content of the fault scarp rocks, and its signature used as a base to decipher the past earthquake history of the fault. We focus on the Magnola normal fault, Central Italy, whose Holocene seismic slip history has already been determined by Palumbo et al. (ESPL, 225, 163-176, 2004) from in situ36Cl cosmic ray exposure dating of the fault limestone scarp surface. Five major earthquakes were found to have occurred over the last 12 ka, with slips of 1.5-3 m and recurrence times of 0.7-3.1 ka. We analyze the major and trace element concentrations of 15 carbonate samples collected from base to top of the 10 m-high Magnola Holocene scarp, next to the previous sampling done by Palumbo et al. [Palumbo, L., Benedetti, L., Bourlès, D., Cinque, A., Finkel, R., 2004. Slip history of the Magnola fault (Apennines, Central Italy) from 36Cl surface exposure dating: evidence for strong earthquake over Holocene. Earth Planet. Sci. Lett. 225, 163-176.]. We find that most element concentrations decrease upscarp at a rate averaging 5%/m. This decrease is attributed to leaching and re-precipitation of purer calcite that increase with exposure time. Superimposed to the overall leaching, concentration peaks are found at the transition zones separating the earthquake ruptures. These concentration peaks likely result from enrichment of the scarp sections that remained stuck in the 30-50 cm-thick impurity-rich upper soil during the quiescence periods that separated the earthquakes. Because the rare earth elements (REE) are among those most significantly enriched at the earthquake transition zones, they are the best chemical markers of past large seismic events. We finally propose a first-order model that reproduces adequately the observations. Our

  14. Review of magnetic field monitoring near active faults and volcanic calderas in California: 1974-1995

    USGS Publications Warehouse

    Mueller, R.J.; Johnston, M.J.S.

    1998-01-01

    Differential magnetic fields have been monitored along the San Andreas fault and the Long Valley caldera since 1974. At each monitoring location, proton precession magnetometers sample total magnetic field intensity at a resolution of 0.1 nT or 0.25 nT. Every 10 min, data samples are transmitted via satellite telemetry to Menlo Park, CA for processing and analysis. The number of active magnetometer sites has varied during the past 21 years from 6 to 25, with 12 sites currently operational. We use this network to identify magnetic field changes generated by earthquake and volcanic processes. During the two decades of monitoring, five moderate earthquakes (M5.9 to M7.3) have occurred within 20 km of magnetometer sites located along the San Andreas fault and only one preseismic signal of 1.5 nT has been observed. During moderate earthquakes, coseismic magnetic signals, with amplitudes from 0.7 nT to 1.3 nT, have been identified for 3 of the 5 events. These observations are generally consistent with those calculated from simple seismomagnetic models of these earthquakes and near-fault coseismic magnetic field disturbances rarely exceed one nanotesla. These data are consistent with the concept of low shear stress and relatively uniform displacement of the San Andreas fault system as expected due to high pore fluid pressure on the fault. A systematic decrease of 0.8-1 nT/year in magnetic field has occurred in the Long Valley caldera since 1989. These magnetic field data are similar in form to observed geodetically measured displacements from inflation of the resurgent dome. A simple volcanomagnetic model involving pressure increase of 50 MPa/a at a depth of 7 km under the resurgent dome can replicate these magnetic field observations. This model is derived from the intrusion model that best fits the surface deformation data. ?? 1998 Elsevier Science B.V.

  15. Determining K/Ar age of fault activity through analysis of clay mineralogy: A case study of "El Doctor Fault", México

    NASA Astrophysics Data System (ADS)

    Garduño, D. E.; Pi, T.; Sole, J.; Martini, M.; Alcala, J. R.

    2013-05-01

    The upper continental crust of Mexico is cut by several major faults, some of which were interpreted as terrane boundaries. Although the age of such faults is key to reconstructing the tectonic evolution of Mexico, geochronologic studies focused on the absolute dating of a fault are scattered. The Doctor fault zone is a decakilometric NNW-SSE structure that produced the overriding of the Lower Cretaceus El Doctor carbonate platform onto foreland calcareous turbidites of Upper Cretaceous Soyatal Formation. In the fault zone, turbidites of the Soyatal Formation display a pervasive foliation at the submillimeter-scale. In calcareous layers, this foliation is defined by seams of opaque minerals concentrated along stilolitic surfaces, whereas in lutitic layers it is defined by iso-oriented fine-grained illite. We collected 17 samples from a traverse across the Doctor fault zone, in order to (1) defining and quantifying fault-related changes in clay mineralogy, (2) studying fabrics in clay-rich fault rocks and protolith, and (3) dating the fault activity by illite K/Ar with laser. Texture was studied with petrographic microscope on polished thin sections. Three size fractions (from 2 μm to 0.05 μm) were extracted using centrifugation. Clay mineralogy was determined using XRD in clay oriented samples and the illite crystallinity (IC) has been determined by the Kübler method (Kisch, 1990). The amount of 2M1 illite was quantified using XRD patterns from a randomly oriented sample, achieved using WILDFIRE (Reynolds, 1994, Haines and Van der Pluijm, 2008) and RIETVELD methods and the timing of fault main activity is determined using K/Ar dating. The mineralogy of the samples consists of quartz, calcite, plagioclase, hematite and clays. The clay mineralogy contain illite (zone 1, zone 2 and zone 3), smectite (zone 2), chlorite (zone 3), kaolinite (zone 1 and zone3), and vermiculite (zone 3). The range of IC (0.24 to 0.4) is attributed to heterogeneous origins of illite

  16. Effects of fluid-rock interactions on faulting within active fault zones - evidence from fault rock samples retrieved from international drilling projects

    NASA Astrophysics Data System (ADS)

    Janssen, C.; Wirth, R.; Kienast, M.; Yabe, Y.; Sulem, J.; Dresen, G. H.

    2015-12-01

    Chemical and mechanical effects of fluids influence the fault mechanical behavior. We analyzed fresh fault rocks from several scientific drilling projects to study the effects of fluids on fault strength. For example, in drill core samples on a rupture plane of an Mw 2.2 earthquake in a deep gold mine in South Africa the main shock occurred on a preexisting plane of weakness that was formed by fluid-rock interaction (magnesiohornblende was intensively altered to chlinochlore). The plane acted as conduit for hydrothermal fluids at some time in the past. The chemical influence of fluids on mineralogical alteration and geomechanical processes in fault core samples from SAFOD (San Andreas Fault Observatory at Depth) is visible in pronounced dissolution-precipitation processes (stylolites, solution seams) as well as in the formation of new phases. Detrital quartz and feldspar grains are partially dissolved and replaced by authigenic illite-smectite (I-S) mixed-layer clay minerals. Transmission Electron Microscopy (TEM) imaging of these grains reveals that the alteration processes and healing were initiated within pores and small intra-grain fissures. Newly formed phyllosilicates growing into open pore spaces likely reduced the fluid permeability. The mechanical influence of fluids is indicated by TEM observations, which document open pores that formed in-situ in the gouge material during or after deformation. Pores were possibly filled with formation water and/or hydrothermal fluids suggesting elevated fluid pressure preventing pore collapse. Fluid-driven healing of fractures in samples from SAFOD and the DGLab Gulf of Corinth project is visible in cementation. Cathodoluminescence microscopy (CL) reveals different generations of calcite veins. Differences in CL-colors suggest repeated infiltration of fluids with different chemical composition from varying sources (formation and meteoric water).

  17. Active faulting in the Inner California Borderlands: new constraints from high-resolution multichannel seismic and multibeam bathymetric data.

    NASA Astrophysics Data System (ADS)

    Bormann, J. M.; Holmes, J. J.; Sahakian, V. J.; Klotsko, S.; Kent, G.; Driscoll, N. W.; Harding, A. J.; Wesnousky, S. G.

    2014-12-01

    Geodetic data indicate that faults offshore of Southern California accommodate 6-8 mm/yr of dextral Pacific-North American relative plate motion. In the Inner California Borderlands (ICB), modern strike-slip deformation is overprinted on topography formed during plate boundary reorganization 30-15 Ma. Despite its proximity to urban Southern California, the hazard posed by active faults in the ICB remains poorly understood. We acquired a 4000-line-km regional grid of high-resolution, 2D multichannel seismic (MCS) reflection data and multibeam bathymetry to examine the fault architecture and tectonic evolution of the ICB. We interpret the MCS data using a sequence stratigraphic approach to establish a chronostratigraphy and identify discrete episodes of deformation. We present our results in a regional fault model that distinguishes active deformation from older structures. Significant differences exist between our model of ICB deformation and existing models. Mounting evidence suggests a westward temporal migration of slip between faults in the ICB. In the eastern ICB, slip on the Newport-Inglewood/Rose Canyon fault and the neighboring Coronado Bank fault (CBF) diminishes to the north and appears to decrease over time. Undeformed Late Pliocene sediments overlie the northern extent of the CBF and the breakaway zone of the purported Oceanside Blind Thrust. Therefore, CBF slip rate estimates based on linkage with the Palos Verdes fault to the north are unwarranted. Deformation along the San Mateo, San Onofre, and Carlsbad trends is best explained as localized deformation resulting from geometrical complexities in a dextral strike-slip fault system. In the western ICB, the San Diego Trough fault (SDTF) offsets young sediments between the US/Mexico border and the eastern margin of Avalon Knoll, where the fault is spatially coincident with the San Pedro Basin fault (SPBF). Farther west, the San Clemente fault (SCF) has a strong linear bathymetric expression. The length

  18. Estimated likelihood of observing a large earthquake on a continental low-angle normal fault and implications for low-angle normal fault activity

    NASA Astrophysics Data System (ADS)

    Styron, Richard H.; Hetland, Eric A.

    2014-04-01

    The lack of observed continental earthquakes that clearly occurred on low-angle normal faults (LANFs) may indicate that these structures are not seismically active or that these earthquakes are simply rare events. To address this, we compile all potentially active continental LANFs (24 in total) and calculate the likelihood of observing a significant earthquake on them over periods of 1-100 years. This probability depends on several factors including the frequency-magnitude distribution. For either a characteristic or Gutenberg-Richter distribution, we calculate a probability of about 0.5 that an earthquake greater than M6.5 (large enough to avoid ambiguity in dip angle) will be observed on any LANF in a period of 35 years, which is the current length of the global centroid moment tensor catalog. We then use Bayes' Theorem to illustrate how the absence of observed significant LANF seismicity over the catalog period moderately decreases the likelihood that the structures generate large earthquakes.

  19. Fault barriers favor activation of backthrusts near segment ends of megathrust ruptures

    NASA Astrophysics Data System (ADS)

    Xu, S.; Fukuyama, E.; Ben-Zion, Y.; Ampuero, J. P.

    2013-12-01

    Increasing evidence indicates that backthrusts may become active during or after megathrust ruptures in subduction zones, such as in Chile and Sumatra areas (Melnick et al., 2012; Singh et al., 2011). Previous studies on relevant mechanisms mainly focused on the interaction between forethrusts and the megathrust. Here we aim to investigate through dynamic rupture simulations how backthrusts may be activated by megathrust ruptures in subduction zone environment. Assuming a single backthrust branch, our preliminary results show that the activation of backthrust is difficult if the megathrust rupture can easily pass through the fault junction, owing to a quickly established stress shadow zone in the wake of the megathrust rupture front. In contrast, if the megathrust rupture is arrested or delayed around the junction, a resultant backward stress lobe of the type discussed by Xu and Ben-Zion (2013) can load the backthrust over a considerable amount of time and facilitates rupture activation along the backthrust. A number of candidates can serve to arrest or delay megathrust ruptures, such as the velocity-strengthening frictional behavior and off-fault weak materials in the shallow portion of subduction zones, fault bend or ramp, and subducted seamount. Moreover, these features are also found capable of generating backthrusts during the long-term quasi-static process, which provide pre-existing weakness to be reactivated by later dynamic ruptures. Our results agree, from a different point of view, with the study based on the critical taper theory (Cubas et al., 2013) that an increase of friction towards the trench favors the activation of backthrusts near the up-dip limit of megathrust ruptures. The results highlight the role of fault geometric or strength heterogeneities in controlling the strain partitioning on and off the main fault plane. Accordingly, activated backthrusts may be treated as markers that reflect the limits of seismogenic zones, and thus may be used

  20. Geomorphic signal of active faulting at the northern edge of Lut Block: Insights on the kinematic scenario of Central Iran

    NASA Astrophysics Data System (ADS)

    Calzolari, Gabriele; Della Seta, Marta; Rossetti, Federico; Nozaem, Reza; Vignaroli, Gianluca; Cosentino, Domenico; Faccenna, Claudio

    2016-01-01

    Recent works documented Neogene to Quaternary dextral strike-slip tectonics along the Kuh-e-Sarhangi and Kuh-e-Faghan intraplate strike-slip faults at the northern edge of the Lut Block of Central Iran, previously thought to be dominated by sinistral strike-slip deformation. This work focuses on the evidence of Quaternary activity of one of these fault systems, in order to provide new spatiotemporal constraints on their role in the active regional kinematic scenario. Through geomorphological and structural investigation, integrated with optically stimulated luminescence dating of three generations of alluvial fans and fluvial terraces (at ~53, ~25, and ~6 ka), this study documents (i) the topographic inheritance of the long-term (Myr) punctuated history of fault nucleation, propagation, and exhumation along the northern edge of Lut Block; (ii) the tectonic control on drainage network evolution, pediment formation, fluvial terraces, and alluvial fan architecture; (iii) the minimum Holocene age of Quaternary dextral strike-slip faulting; and (iv) the evidence of Late Quaternary fault-related uplift localized along the different fault strands. The documented spatial and temporal constraints on the active dextral strike-slip tectonics at the northern edge of Lut Block provide new insights on the kinematic model for active faulting in Central Iran, which has been reinterpreted in an escape tectonic scenario.

  1. FTAPE: A fault injection tool to measure fault tolerance

    NASA Technical Reports Server (NTRS)

    Tsai, Timothy K.; Iyer, Ravishankar K.

    1994-01-01

    The paper introduces FTAPE (Fault Tolerance And Performance Evaluator), a tool that can be used to compare fault-tolerant computers. The tool combines system-wide fault injection with a controllable workload. A workload generator is used to create high stress conditions for the machine. Faults are injected based on this workload activity in order to ensure a high level of fault propagation. The errors/fault ratio and performance degradation are presented as measures of fault tolerance.

  2. FTAPE: A fault injection tool to measure fault tolerance

    NASA Technical Reports Server (NTRS)

    Tsai, Timothy K.; Iyer, Ravishankar K.

    1995-01-01

    The paper introduces FTAPE (Fault Tolerance And Performance Evaluator), a tool that can be used to compare fault-tolerant computers. The tool combines system-wide fault injection with a controllable workload. A workload generator is used to create high stress conditions for the machine. Faults are injected based on this workload activity in order to ensure a high level of fault propagation. The errors/fault ratio and performance degradation are presented as measures of fault tolerance.

  3. Active out-of-sequence thrust faulting in the central Nepalese Himalaya.

    PubMed

    Wobus, Cameron; Heimsath, Arjun; Whipple, Kelin; Hodges, Kip

    2005-04-21

    Recent convergence between India and Eurasia is commonly assumed to be accommodated mainly along a single fault--the Main Himalayan Thrust (MHT)--which reaches the surface in the Siwalik Hills of southern Nepal. Although this model is consistent with geodetic, geomorphic and microseismic data, an alternative model incorporating slip on more northerly surface faults has been proposed to be consistent with these data as well. Here we present in situ cosmogenic 10Be data indicating a fourfold increase in millennial timescale erosion rates occurring over a distance of less than 2 km in central Nepal, delineating for the first time an active thrust fault nearly 100 km north of the surface expression of the MHT. These data challenge the view that rock uplift gradients in central Nepal reflect only passive transport over a ramp in the MHT. Instead, when combined with previously reported 40Ar-39Ar data, our results indicate persistent exhumation above deep-seated, surface-breaking structures at the foot of the high Himalaya. These results suggest that strong dynamic interactions between climate, erosion and tectonics have maintained a locus of active deformation well to the north of the Himalayan deformation front.

  4. Recent tectonic activity on Mercury revealed by small thrust fault scarps

    NASA Astrophysics Data System (ADS)

    Watters, Thomas R.; Daud, Katie; Banks, Maria E.; Selvans, Michelle M.; Chapman, Clark R.; Ernst, Carolyn M.

    2016-10-01

    Large tectonic landforms on the surface of Mercury, consistent with significant contraction of the planet, were revealed by the flybys of Mariner 10 in the mid-1970s. The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission confirmed that the planet's past 4 billion years of tectonic history have been dominated by contraction expressed by lobate fault scarps that are hundreds of kilometres long. Here we report the discovery of small thrust fault scarps in images from the low-altitude campaign at the end of the MESSENGER mission that are orders of magnitude smaller than the large-scale lobate scarps. These small scarps have tens of metres of relief, are only kilometres in length and are comparable in scale to small young scarps on the Moon. Their small-scale, pristine appearance, crosscutting of impact craters and association with small graben all indicate an age of less than 50 Myr. We propose that these scarps are the smallest members of a continuum in scale of thrust fault scarps on Mercury. The young age of the small scarps, along with evidence for recent activity on large-scale scarps, suggests that Mercury is tectonically active today and implies a prolonged slow cooling of the planet's interior.

  5. On the possible fault activation induced by UGS in depleted reservoirs

    NASA Astrophysics Data System (ADS)

    Feronato, Massimiliano; Gambolati, Giuseppe; Janna, Carlo; Teatini, Pietro; Tosattto, Omar

    2014-05-01

    Underground gas storage (UGS) represents an increasingly used approach to cope with the growing energy demand and occurs in many countries worldwide. Gas is injected in previously depleted deep reservoirs during summer when consumption is limited and removed in cold season mainly for heating. As a major consequence the pore pressure p within a UGS reservoir fluctuates yearly between a maximum close to the value pi prior to the field development and a minimum usually larger than the lowest pressure experienced by the reservoir at the end of its production life. The high frequency pressure fluctuations generally confine the pressure change volume to the reservoir volume without significantly involving the aquifers hydraulically connected to the hydrocarbon field (lateral and/or bottom waterdrive). The risk of UGS-induced seismicity is therefore restricted to those cases where existing faults cross or bound the reservoir. The possible risk of anthropogenic seismicity due to UGS operations is preliminary investigated by an advanced Finite Element (FE) - Interface Element (IE) 3-D elasto-plastic geomechanical model in a representative 1500 m deep reservoir bounded by a regional sealing fault and compartimentalized by an internal non-sealing thrust. Gas storage/production is ongoing with p ranging between pi in October/November and 60%pi in April/May. The yearly pressure fluctuation is assumed to be on the order of 50 bar. The overall geomechanical response of the porous medium has been calibrated by reproducing the vertical and horizontal cyclic displacements measured above the reservoir by advanced persistent scatterer interferometry. The FE-IE model shows that the stress variations remain basically confined within the gas field and negligibly propagate within the caprock and the waterdrive. Based on the Mohr-Coulomb failure criterion, IEs allow for the prediction of the fault activated area A, located at the reservoir depth as expected, and slip displacement d. A

  6. Fault mechanics

    SciTech Connect

    Segall, P. )

    1991-01-01

    Recent observational, experimental, and theoretical modeling studies of fault mechanics are discussed in a critical review of U.S. research from the period 1987-1990. Topics examined include interseismic strain accumulation, coseismic deformation, postseismic deformation, and the earthquake cycle; long-term deformation; fault friction and the instability mechanism; pore pressure and normal stress effects; instability models; strain measurements prior to earthquakes; stochastic modeling of earthquakes; and deep-focus earthquakes. Maps, graphs, and a comprehensive bibliography are provided. 220 refs.

  7. Planning a Preliminary program for Earthquake Loss Estimation and Emergency Operation by Three-dimensional Structural Model of Active Faults

    NASA Astrophysics Data System (ADS)

    Ke, M. C.

    2015-12-01

    Large scale earthquakes often cause serious economic losses and a lot of deaths. Because the seismic magnitude, the occurring time and the occurring location of earthquakes are still unable to predict now. The pre-disaster risk modeling and post-disaster operation are really important works of reducing earthquake damages. In order to understanding disaster risk of earthquakes, people usually use the technology of Earthquake simulation to build the earthquake scenarios. Therefore, Point source, fault line source and fault plane source are the models which often are used as a seismic source of scenarios. The assessment results made from different models used on risk assessment and emergency operation of earthquakes are well, but the accuracy of the assessment results could still be upgrade. This program invites experts and scholars from Taiwan University, National Central University, and National Cheng Kung University, and tries using historical records of earthquakes, geological data and geophysical data to build underground three-dimensional structure planes of active faults. It is a purpose to replace projection fault planes by underground fault planes as similar true. The analysis accuracy of earthquake prevention efforts can be upgraded by this database. Then these three-dimensional data will be applied to different stages of disaster prevention. For pre-disaster, results of earthquake risk analysis obtained by the three-dimensional data of the fault plane are closer to real damage. For disaster, three-dimensional data of the fault plane can be help to speculate that aftershocks distributed and serious damage area. The program has been used 14 geological profiles to build the three dimensional data of Hsinchu fault and HisnCheng faults in 2015. Other active faults will be completed in 2018 and be actually applied on earthquake disaster prevention.

  8. Locating an active fault zone in Coso geothermal field by analyzing seismic guided waves from microearthquake data

    SciTech Connect

    SGP-TR-150-16

    1995-01-26

    Active fault systems usually provide high-permeability channels for hydrothermal outflow in geothermal fields. Locating such fault systems is of a vital importance to plan geothermal production and injection drilling, since an active fault zone often acts as a fracture-extensive low-velocity wave guide to seismic waves. We have located an active fault zone in the Coso geothermal field, California, by identifying and analyzing a fault-zone trapped Rayleigh-type guided wave from microearthquake data. The wavelet transform is employed to characterize guided-wave's velocity-frequency dispersion, and numerical methods are used to simulate the guided-wave propagation. The modeling calculation suggests that the fault zone is {approx} 200m wide, and has a P wave velocity of 4.80 km/s and a S wave velocity of 3.00 km/s, which is sandwiched between two half spaces with relatively higher velocities (P wave velocity 5.60 km/s, and S wave velocity 3.20 km/s). zones having vertical or nearly vertical dipping fault planes.

  9. Levelling Profiles and a GPS Network to Monitor the Active Folding and Faulting Deformation in the Campo de Dalias (Betic Cordillera, Southeastern Spain)

    PubMed Central

    Marín-Lechado, Carlos; Galindo-Zaldívar, Jesús; Gil, Antonio José; Borque, María Jesús; de Lacy, María Clara; Pedrera, Antonio; López-Garrido, Angel Carlos; Alfaro, Pedro; García-Tortosa, Francisco; Ramos, Maria Isabel; Rodríguez-Caderot, Gracia; Rodríguez-Fernández, José; Ruiz-Constán, Ana; de Galdeano-Equiza, Carlos Sanz

    2010-01-01

    The Campo de Dalias is an area with relevant seismicity associated to the active tectonic deformations of the southern boundary of the Betic Cordillera. A non-permanent GPS network was installed to monitor, for the first time, the fault- and fold-related activity. In addition, two high precision levelling profiles were measured twice over a one-year period across the Balanegra Fault, one of the most active faults recognized in the area. The absence of significant movement of the main fault surface suggests seismogenic behaviour. The possible recurrence interval may be between 100 and 300 y. The repetitive GPS and high precision levelling monitoring of the fault surface during a long time period may help us to determine future fault behaviour with regard to the existence (or not) of a creep component, the accumulation of elastic deformation before faulting, and implications of the fold-fault relationship. PMID:22319309

  10. Ground Motion Simulation for a Large Active Fault System using Empirical Green's Function Method and the Strong Motion Prediction Recipe - a Case Study of the Noubi Fault Zone -

    NASA Astrophysics Data System (ADS)

    Kuriyama, M.; Kumamoto, T.; Fujita, M.

    2005-12-01

    propagation. Moreover, it was clarified that the horizontal velocities by assuming the cascade model was underestimated more than one standard deviation of empirical relation by Si and Midorikawa (1999). The scaling and cascade models showed an approximately 6.4-fold difference for the case, in which the rupture started along the southeastern edge of the Umehara Fault at observation point GIF020. This difference is significantly large in comparison with the effect of different rupture starting points, and shows that it is important to base scenario earthquake assumptions on active fault datasets before establishing the source characterization model. The distribution map of seismic intensity for the 1891 Noubi Earthquake also suggests that the synthetic waveforms in the southeastern Noubi Fault zone may be underestimated. Our results indicate that outer fault parameters (e.g., earthquake moment) related to the construction of scenario earthquakes influence strong motion prediction, rather than inner fault parameters such as the rupture starting point. Based on these methods, we will predict strong motion for approximately 140 to 150 km of the Itoigawa-Shizuoka Tectonic Line.

  11. Earthquake cycle associated with active strike slip faults in central Panamá

    NASA Astrophysics Data System (ADS)

    Rick, Bennett; Spinler, Joshua C.; Compton, Kathleen; Rockwell, Thomas K.; Gath, Eldon

    2013-04-01

    The rigidity of the Panamá Isthmus is currently under debate, with important implications for seismic hazards to the Panamá Canal and Panamá City. Whereas Panamá has traditionally been described as a non-deforming microplate caught between a number of larger tectonic plates, new paleoseismic data collected at a limited number of trench sites in association with the ongoing expansion of the Panamá Canal may challenge the validity of the rigid microplate hypothesis. Crustal velocities from a new, ~100 km aperture, 5-station continuous GPS network constructed across the Rio Gatún, Limón, and Pedro Miguel fault zones confirm that these fault zones are active, forming a system of faults that traverse central Panamá in close proximity to the Panamá Canal and Panamá City. However, the slip rates inferred from these new geodetic data are lower than the geologic rates when using an elastic halfspace model. Differences among previous geodetic investigations, which concluded that Panamá is rigid, and the geological slip rate estimates are explained by earthquake cycle effects associated with long recurrence intervals relative to lower crust and upper mantle Maxwell relaxation times. Late in the earthquake cycle the geodetic strain field is broadly distributed, giving the false appearance of low seismic hazards.

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

  13. Fault diagnosis

    NASA Technical Reports Server (NTRS)

    Abbott, Kathy

    1990-01-01

    The objective of the research in this area of fault management is to develop and implement a decision aiding concept for diagnosing faults, especially faults which are difficult for pilots to identify, and to develop methods for presenting the diagnosis information to the flight crew in a timely and comprehensible manner. The requirements for the diagnosis concept were identified by interviewing pilots, analyzing actual incident and accident cases, and examining psychology literature on how humans perform diagnosis. The diagnosis decision aiding concept developed based on those requirements takes abnormal sensor readings as input, as identified by a fault monitor. Based on these abnormal sensor readings, the diagnosis concept identifies the cause or source of the fault and all components affected by the fault. This concept was implemented for diagnosis of aircraft propulsion and hydraulic subsystems in a computer program called Draphys (Diagnostic Reasoning About Physical Systems). Draphys is unique in two important ways. First, it uses models of both functional and physical relationships in the subsystems. Using both models enables the diagnostic reasoning to identify the fault propagation as the faulted system continues to operate, and to diagnose physical damage. Draphys also reasons about behavior of the faulted system over time, to eliminate possibilities as more information becomes available, and to update the system status as more components are affected by the fault. The crew interface research is examining display issues associated with presenting diagnosis information to the flight crew. One study examined issues for presenting system status information. One lesson learned from that study was that pilots found fault situations to be more complex if they involved multiple subsystems. Another was pilots could identify the faulted systems more quickly if the system status was presented in pictorial or text format. Another study is currently under way to

  14. Deep reaching versus vertically restricted Quaternary normal faults: Implications on seismic potential assessment in tectonically active regions: Lessons from the middle Aterno valley fault system, central Italy

    NASA Astrophysics Data System (ADS)

    Falcucci, E.; Gori, S.; Moro, M.; Fubelli, G.; Saroli, M.; Chiarabba, C.; Galadini, F.

    2015-05-01

    We investigate the Middle Aterno Valley fault system (MAVF), a poorly investigated seismic gap in the central Apennines, adjacent to the 2009 L'Aquila earthquake epicentral area. Geological and paleoseismological analyses revealed that the MAVF evolved through hanging wall splay nucleation, its main segment moving at 0.23-0.34 mm/year since the Middle Pleistocene; the penultimate activation event occurred between 5388-5310 B.C. and 1934-1744 B.C., the last event after 2036-1768 B.C. and just before 1st-2nd century AD. These data define hard linkage (sensu Walsh and Watterson, 1991; Peacock et al., 2000; Walsh et al., 2003, and references therein) with the contiguous Subequana Valley fault segment, able to rupture in large magnitude earthquakes (up to 6.8), that did not rupture since about two millennia. By the joint analysis of geological observations and seismological data acquired during to the 2009 seismic sequence, we derive a picture of the complex structural framework of the area comprised between the MAVF, the Paganica fault (the 2009 earthquake causative fault) and the Gran Sasso Range. This sector is affected by a dense array of few-km long, closely and regularly spaced Quaternary normal fault strands, that are considered as branches of the MAVF northern segment. Our analysis reveals that these structures are downdip confined by a decollement represented by to the presently inactive thrust sheet above the Gran Sasso front limiting their seismogenic potential. Our study highlights the advantage of combining Quaternary geological field analysis with high resolution seismological data to fully unravel the structural setting of regions where subsequent tectonic phases took place and where structural interference plays a key role in influencing the seismotectonic context; this has also inevitably implications for accurately assessing seismic hazard of such structurally complex regions.

  15. How Faults Shape the Earth.

    ERIC Educational Resources Information Center

    Bykerk-Kauffman, Ann

    1992-01-01

    Presents fault activity with an emphasis on earthquakes and changes in continent shapes. Identifies three types of fault movement: normal, reverse, and strike faults. Discusses the seismic gap theory, plate tectonics, and the principle of superposition. Vignettes portray fault movement, and the locations of the San Andreas fault and epicenters of…

  16. Late Quaternary reef growth history of Les Saintes submarine plateau: a key to constrain active faulting kinematics in Guadeloupe (FWI)

    NASA Astrophysics Data System (ADS)

    Leclerc, F.; Feuillet, N.; Deplus, C.; Cabioch, G.; Tapponnier, P.; LeBrun, J.; Bazin, S.; Beauducel, F.; Boudon, G.; Le Friant, A.; De Min, L.; Melezan, D.

    2012-12-01

    hazard. Joint analysis of the aftershocks sequence and the fault map provide a good image of the fault system recent activity. Finally, we deduced fault kinematics with respect to Holocene reef demise timing, and obtained a mean slip rate of several tenth of mm/yr on each fault, comparable to the slip rate of the near active Morne-Piton fault. Thus, the fault system could generate a Mw 6 earthquake every 250 yrs.

  17. Coastal Marine Terraces Define Late Quaternary Fault Activity and Deformation Within Northern East Bay Hills, San Francisco Bay Region

    NASA Astrophysics Data System (ADS)

    Kelson, K. I.

    2004-12-01

    Detailed mapping of uplifted marine platforms bordering the Carquinez Strait between Benicia and Pinole, California, provides data on the pattern and rate of late Quaternary deformation across the northern East Bay Hills. Field mapping, interpretation of early 20th-century topographic data, analysis of aerial photography, and compilation of onshore borehole data show the presence of remnants of three platforms, with back-edge elevations of about 4 m, 12 m, and 18 m. Based on U-series dates (Helley et al., 1993) and comparison of platform elevations to published sea-level curves, the 12-m-high and 18-m-high platforms correlate with substage 5e (ca. 120 ka) and stage 9 (ca. 330 ka) sea-level high stands, respectively. West of the Southhampton fault, longitudinal profiles of platform back-edges suggest that the East Bay Hills between Pinole and Vallejo have undergone block uplift at a rate of 0.05 +/- 0.01 m/ka without substantial tilting or warping. With uncertainty of <3 m, the 120 ka and 330 ka platforms are at the same elevations across the NW-striking Franklin fault. This west-vergent reverse fault previously was interpreted to have had late Pleistocene activity and to accommodate crustal shortening in the East Bay Hills. Our data indicate an absence of vertical displacement across the Franklin fault within at least the past 120ka and perhaps 330ka. In contrast, the stage 5e and 9 have up-on-the-east vertical displacement and gentle westward tilting across the N-striking Southhampton fault, with a late Pleistocene vertical slip rate of >0.02 m/ka. The northerly strike and prominent geomorphic expression of this potentially active fault differs from the Franklin fault. Our mapping of the Southhampton fault suggests that it accommodates dextral shear in the East Bay Hills, and is one of several left-stepping, en echelon N-striking faults (collectively, the "Contra Costa shear zone", CCSZ) in the East Bay Hills. Faults within this zone coincide with geomorphic

  18. Effects of fluids on faulting within active fault zones - evidence from drill core samples recovered during the San Andreas Fault Observatory at Depth (SAFOD) drilling project

    NASA Astrophysics Data System (ADS)

    Janssen, C.; Wirth, R.; Kienast, M.; Morales, L. G.; Rybacki, E.; Wenk, H.; Dresen, G. H.

    2011-12-01

    Low temperature microstructures observed in samples from SAFOD drill cores indicate fluid-related deformation and chemical reactions occurring simultaneously and interacting with each other. Transmission Electron Microscopy (TEM) observations, document open pores that formed in-situ during or after deformation. In TEM images, many pores with high aspect ratio appear to be unconnected. They were possibly filled with formation water and/or hydrothermal fluids suggesting that elevated pore fluid pressure exist in the fault gouge, preventing pore collapse. The chemical influence of fluids on mineralogical alteration and geomechanical processes in fault rocks is visible in pronounced dissolution-precipitation processes (stylolites, solution seams) as well as in the formation of new phases. Detrital quartz and feldspar grains are partially dissolved and replaced by authigenic illite-smectite (I-S) mixed-layer clay minerals. TEM imaging of these grains reveals that the alteration processes initiated within pores and small intra-grain fissures. In few samples syntectonic fluid-assisted overgrowth of chlorite-rich films on slickensides partly replaced sedimentary quartz grains. Quartz and feldspar grains are partially dissolved with sutured boundaries. Newly-formed phyllosilicates are illite-smectite phases, Mg-rich smectites and chlorite minerals. They are very fine-grained (down to 20 nm) and nucleate at grain surfaces (interfaces), which in many cases are pore or fracture walls. These relatively straight or curved crystals grow into open pore spaces and fractures. They are arranged in a card-house fabric with open pore spaces between the flakes. Locally, clay flakes are bent, folded or show sigmoidal shapes indicating that they were involved in faulting. The clay particles do not show a preferred shape orientation. The predominantly random orientation distribution of the clay minerals was confirmed by x-ray synchrotron texture analysis. Pole figures show very weak

  19. Landform development in a zone of active Gedi Fault, Eastern Kachchh rift basin, India

    NASA Astrophysics Data System (ADS)

    Kothyari, Girish Ch.; Rastogi, B. K.; Morthekai, P.; Dumka, Rakesh K.

    2016-02-01

    An earthquake of 2006 Mw 5.7 occurred along east-west trending Gedi Fault (GF) to the north of the Kachchh rift basin in western India which had the epicenter in the Wagad upland, which is approximately 60 km northeast of the 2001 Mw 7.7 earthquake site (or epicenter). Development of an active fault scarp, shifting of a river channel, offsetting of streams and uplift of the ground indicate that the terrain is undergoing active deformation. Based on detailed field investigations, three major faults that control uplifts have been identified in the GF zone. These uplifts were developed in a step-over zone of the GF, and formed due to compressive force generated by left-lateral motion within the segmented blocks. In the present research, a terrace sequence along the north flowing Karaswali river in a tectonically active GF zone has been investigated. Reconstructions based on geomorphology and terrace stratigraphy supported by optical chronology suggest that the fluvial aggradation in the Wagad area was initiated during the strengthening (at ~ 8 ka) and declining (~ 4 ka) of the Indian Summer Monsoon (ISM). The presence of younger valley fill sediments which are dated ~ 1 ka is ascribed to a short lived phase of renewed strengthening of ISM before present day aridity. Based on terrace morphology two major phases of enhanced uplift have been estimated. The older uplift event dated to 8 ka is represented by the Tertiary bedrock surfaces which accommodated the onset of valley-fill aggradation. The younger event of enhanced uplift dated to 4 ka was responsible for the incision of the older valley fill sediments and the Tertiary bedrock. These ages suggest that the average rate of uplift ranges from 0.3 to 1.1 mm/yr during the last 9 ka implying active nature of the area.

  20. Active faults in the deformation zone off Noto Peninsula, Japan, revealed by high- resolution seismic profiles

    NASA Astrophysics Data System (ADS)

    Inoue, T.; Okamura, Y.; Murakami, F.; Kimura, H.; Ikehara, K.

    2008-12-01

    Recently, a lot of earthquakes occur in Japan. The deformation zone which many faults and folds have concentrated exists on the Japan Sea side of Japan. The 2007 Noto Hanto Earthquake (MJMA 6.9) and 2007 Chuetsu-oki Earthquake (MJMA 6.8) were caused by activity of parts of faults in this deformation zone. The Noto Hanto Earthquake occurred on 25 March, 2007 under the northwestern coast of Noto Peninsula, Ishikawa Prefecture, Japan. This earthquake is located in Quaternary deformation zone that is continued from northern margin of Noto Peninsula to southeast direction (Okamura, 2007a). National Institute of Advanced Industrial Science and Technology (AIST) carried out high-resolution seismic survey using Boomer and 12 channels short streamer cable in the northern part off Noto Peninsula, in order to clarify distribution and activities of active faults in the deformation zone. A twelve channels short streamer cable with 2.5 meter channel spacing developed by AIST and private corporation is designed to get high resolution seismic profiles in shallow sea area. The multi-channel system is possible to equip on a small fishing boat, because the data acquisition system is based on PC and the length of the cable is short and easy to handle. Moreover, because the channel spacing is short, this cable is very effective for a high- resolution seismic profiling survey in the shallow sea, and seismic data obtained by multi-channel cable can be improved by velocity analysis and CDP stack. In the northern part off Noto Peninsula, seismic profiles depicting geologic structure up to 100 meters deep under sea floor were obtained. The most remarkable reflection surface recognized in the seismic profiles is erosion surface at the Last Glacial Maximum (LGM). In the western part, sediments about 30 meters (40 msec) thick cover the erosional surface that is distributed under the shelf shallower than 100m in depth and the sediments thin toward offshore and east. Flexures like deformation in

  1. Impact of the Yakutat indentor corner on present-day tectonics and fault activity in SE Alaska - SW Yukon

    NASA Astrophysics Data System (ADS)

    Mazzotti, S.; Marechal, A.; Ritz, J. F.; Ferry, M. A.

    2015-12-01

    We present an active tectonic model of the SE Alaska - SW Yukon region based principally on the integration of recent GPS velocity data and new fault-slip rates derived from geomorphology. In this region, the Yakutat collision results in complex tectonics with patterns of strain localization and strain partitioning that strongly vary across the various mountain ranges and active faults. We propose that deformation and fault activity in the St. Elias and Chugach Mountains are primarily controlled by the eastern syntaxis of the Yakutat collision, which produces a semi-radial tectonic pattern: Velocities, principal horizontal shortening rates, and maximum horizontal stress orientations rotate by 60 - 80 ° around the syntaxis, from roughly parallel to the relative Pacific - North America motion at the front of the collision to roughly orthogonal southeast of the syntaxis. The interaction between this strain pattern and major inherited tectonic structures inland of the collision zone (i.e., Denali and Duke River Faults) results in various reactivation modes of these structures. Specifically, the Denali Fault shows a very pronounced lateral variations of activity from ~12 mm/a of dextral slip rate in its central section to ~1 mm/a of mostly shortening slip rate along its southern section. This marked change of activity is associated with a possible relay system where the Duke River and Totschunda Faults accommodate a major part (8 - 12 mm/a) of the inland strain transfer directly in front of the syntaxis. This new tectonic model retains some questions, in particular regarding the mechanisms of deformation and strain transfer (1) from the syntaxis to the Duke River - Totschunda system and (2) at the junction between Totschunda and Denali Faults. Numerical models of present-day deformation may help address these issues and provide information about relative strength of the various crustal and inherited fault elements of this system.

  2. dMODELS: A MATLAB software package for modeling crustal deformation near active faults and volcanic centers

    NASA Astrophysics Data System (ADS)

    Battaglia, Maurizio; Cervelli, Peter F.; Murray, Jessica R.

    2013-03-01

    We have developed a MATLAB software package for the most common models used to interpret deformation measurements near faults and active volcanic centers. The emphasis is on analytical models of deformation that can be compared with data from the Global Positioning System (GPS), InSAR, tiltmeters and strainmeters. Source models include pressurized spherical, ellipsoidal and sill-like magma chambers in an elastic, homogeneous, flat half-space. Dikes and faults are described following the mathematical notation for rectangular dislocations in an elastic, homogeneous, flat half-space. All the expressions have been checked for typographical errors that might have been present in the original literature, extended to include deformation and strain within the Earth's crust (as opposed to only the Earth's surface) and verified against finite element models. A set of GPS measurements from the 2006 eruption at Augustine Volcano (Alaska) is used to test the software package. The results show that the best fit source to the GPS data is a spherical intrusion (ΔV=5×10 km3), about 880 m beneath the volcano's summit.

  3. Physical modeling of the formation and evolution of seismically active fault zones

    USGS Publications Warehouse

    Ponomarev, A.V.; Zavyalov, A.D.; Smirnov, V.B.; Lockner, D.A.

    1997-01-01

    Acoustic emission (AE) in rocks is studied as a model of natural seismicity. A special technique for rock loading has been used to help study the processes that control the development of AE during brittle deformation. This technique allows us to extend to hours fault growth which would normally occur very rapidly. In this way, the period of most intense interaction of acoustic events can be studied in detail. Characteristics of the acoustic regime (AR) include the Gutenberg-Richter b-value, spatial distribution of hypocenters with characteristic fractal (correlation) dimension d, Hurst exponent H, and crack concentration parameter Pc. The fractal structure of AR changes with the onset of the drop in differential stress during sample deformation. The change results from the active interaction of microcracks. This transition of the spatial distribution of AE hypocenters is accompanied by a corresponding change in the temporal correlation of events and in the distribution of event amplitudes as signified by a decrease of b-value. The characteristic structure that develops in the low-energy background AE is similar to the sequence of the strongest microfracture events. When the AR fractal structure develops, the variations of d and b are synchronous and d = 3b. This relation which occurs once the fractal structure is formed only holds for average values of d and b. Time variations of d and b are anticorrelated. The degree of temporal correlation of AR has time variations that are similar to d and b variations. The observed variations in laboratory AE experiments are compared with natural seismicity parameters. The close correspondence between laboratory-scale observations and naturally occurring seismicity suggests a possible new approach for understanding the evolution of complex seismicity patterns in nature. ?? 1997 Elsevier Science B.V. All rights reserved.

  4. Searching for Active Faults in the Western Eurasia-Nubia plate boundary

    NASA Astrophysics Data System (ADS)

    Antunes, Veronica; Custodio, Susana; Arroucau, Pierre; Carrilho, Fernando

    2016-04-01

    The repeated occurrence of large magnitude earthquakes in southwest Iberia in historical and instrumental times suggests the presence of active faults in the region. However, the region undergoes slow deformation, which results in low rates of seismic activity, and the location, dimension and geometry of active structures remains unsettled. We recently developed a new algorithm for earthquake location in 3D complex media with laterally varying interface depths, which allowed us to relocate 2363 events that occurred from 2007 to 2013. The method takes as inputs P- and S-wave catalog arrival times obtained from the Portuguese Meteorological Institute (IPMA, Instituto Portugues do Mar e da Atmosfera), for a study area defined by 8.5°W < lon < 5°W and 36° < lat < 37.5°. After relocation, we obtain a lineation of events in the Guadalquivir bank region, in the northern Gulf of Cadiz. The lineation defines a low-angle northward-dipping plane rooted at the base of the crust, which could indicate the presence of a major fault. We provide seismological evidence for the existence of this seemingly active structure based on earthquake relocations, focal mechanisms and waveform similarity between neighboring events.

  5. Fault activation after vigorous eruption: the December 8, 2015 seismic swarm at Mt. Etna

    NASA Astrophysics Data System (ADS)

    Alparone, Salvatore; Bonforte, Alessandro; Guglielmino, Francesco; Maiolino, Vincenza; Puglisi, Giuseppe; Ursino, Andrea

    2016-04-01

    From December 2, 2015, volcanic activity suddenly occurred on Mt. Etna with very violent fire fountaining at central crater, known also as "Voragine". This activity continued with other intense episodes at the same crater during the three following days and involving also, in turn, all the other three summit craters. This sudden eruption produced a rapid deflation of the volcano and was followed, from December 8, by a seismic swarm, with almost eighty earthquakes during this day, located on the uppermost segment of the Pernicana-Provenzana fault system (PFS). This seismicity was characterized by shallow foci (from few hundred meters until 1.5 km below the sea level) and mainshock with 3.6 magnitude. In order to investigate and measure the dynamics controlling and accompanying the PFS activation, a dataset composed of C-Band Sentinel-1A data has been used for SAR Interferometry (InSAR) analysis. Some interferograms have been generated from ascending and descending orbits in order to analyze both short- and long-term deformation. The availability of GPS data allowed comparing and integrating them with InSAR for ground truth and modeling aims. The surface kinematics and modeling obtained by DInSAR and GPS data and integration have been compared to the distribution of the seismicity and related focal mechanisms in order to define the fault geometry and motion. Moreover, essential constraints have been achieved about the PFS dynamic and its relationship with the intense volcanic activity occurred.

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

    USGS Publications Warehouse

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

    2007-01-01

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

  7. Advanced fault management for the Space Station External Active Thermal Control System

    NASA Astrophysics Data System (ADS)

    Morris, William S.; Hill, Timothy; Robertson, Charles

    1992-07-01

    The Thermal Control System Automation Project is developing three related software systems. The first is a high-fidelity simulator of the Space Station Freedom (SSF) External Active Thermal Control System (EATCS), which provides heating, cooling, and control necessary to maintain elements, systems, and components within their required temperature range. The second is an SSF run-time object data base. The third is a knowledge-based system (KBS) to monitor, control, and perform fault detection, isolation, and recovery on the SSF EATCS. The paper describes the EATCS hardware, the KBS design, the model-based sensor validation, the rule-based diagnosis, human interface issues, and future plans for the KBS.

  8. Active tendon control of reinforced concrete frame structures subjected to near-fault effects

    NASA Astrophysics Data System (ADS)

    Nigdeli, Sinan Melih; Boduroǧlu, M. Hasan

    2013-10-01

    A reinforced concrete (RC) frame structure was controlled with active tendons under the excitation of near-fault ground motions. Proportional Integral Derivative (PID) type controllers were used and the controller was tuned by using a numerical algorithm. In order to prevent brittle fracture of the structure, the aim of the control is to reduce maximum base shear force. The RC structure was investigated for different characteristic strengths of concrete and the approach is applicable for the structure with 14 MPa concrete strength or higher.

  9. Long-term High-Quality Deformation Observations near Active Faults in California

    NASA Astrophysics Data System (ADS)

    Agnew, D. C.; Wyatt, F. K.

    2014-12-01

    For monitoring and for improved understanding of the seismic cycle we have collected continuous deformation data close to the two most active faults in Southern California over the past few decades. Pinyon Flat Observatory (PFO) is 14 km from the Anza section of the San Jacinto fault (slip rate 10-15 mm/yr), which has not produced a large earthquake in the past 200 years; Salton City (SCS) is within 15 km of the blind section of the fault further SE. Two locations (Cholame, or CHL, and Durmid Hill, or DHL) are within three km of the San Andreas fault (SAF): CHL, at the N end of the segment that ruptured in 1857, and DHL at the S end of the segment that ruptured about 1700. All these observatories use laser strainmeters (LSM's), 400 to 700 m long, and located on the surface with endpoints anchored 25 m deep. These instruments provide unique long-term high-quality measurements of strain; in geological settings from slightly weathered granite to lake-bed clay sediments, the LSM data record secular strain accumulation consistent with continuous GPS, while covering the temporal range from seismic waves to secular changes. At periods less than a few months, the LSM noise level is far below that from fault-scale GPS networks.The LSM sites near the SAF show strain-rate fluctuations over periods of months and longer of up to 20 percent of the long-term rate, and have also observed aseismic strain events lasting hours to days. At CHL these short-term signals have been observed on borehole strainmeters nearby, and there and at DHL they appear to be a few km deep. Aseismic signals observed at PFO seem to be nearer to the seismogenic zone. In most cases further interpretation has been hampered by not having similar measurements at other locations, but the existing LSM data have been used to rule out possible aseismic strains from nearby earthquake swarms (DHL) and deep tremor (CHL).The LSM data and other measurements at the observatories, confirm how important patience and

  10. Active faulting at Delphi, Greece: Seismotectonic remarks and a hypothesis for the geologic environment of a myth

    NASA Astrophysics Data System (ADS)

    Piccardi, Luigi

    2000-07-01

    Historical data are fundamental to the understanding of the seismic history of an area. At the same time, knowledge of the active tectonic processes allows us to understand how earthquakes have been perceived by past cultures. Delphi is one of the principal archaeological sites of Greece, the main oracle of Apollo. It was by far the most venerated oracle of the Greek ancient world. According to tradition, the mantic proprieties of the oracle were obtained from an open chasm in the earth. Delphi is directly above one of the main antithetic active faults of the Gulf of Corinth Rift, which bounds Mount Parnassus to the south. The geometry of the fault and slip-parallel lineations on the main fault plane indicate normal movement, with minor right-lateral slip component. Combining tectonic data, archaeological evidence, historical sources, and a reexamination of myths, it appears that the Helice earthquake of 373 B.C. ruptured not only the master fault of the Gulf of Corinth Rift at Helice, but also the antithetic fault at Delphi, similarly to the Corinth earthquake of 1981. Moreover, the presence of an active fault directly below the temples of the oldest sanctuary suggests that the mythological oracular chasm might well have been an ancient tectonic surface rupture.

  11. Widespread active detachment faulting and core complex formation near 13 degrees N on the Mid-Atlantic Ridge.

    PubMed

    Smith, Deborah K; Cann, Johnson R; Escartín, Javier

    2006-07-27

    Oceanic core complexes are massifs in which lower-crustal and upper-mantle rocks are exposed at the sea floor. They form at mid-ocean ridges through slip on detachment faults rooted below the spreading axis. To date, most studies of core complexes have been based on isolated inactive massifs that have spread away from ridge axes. Here we present a survey of the Mid-Atlantic Ridge near 13 degrees N containing a segment in which a number of linked detachment faults extend for 75 km along one flank of the spreading axis. The detachment faults are apparently all currently active and at various stages of development. A field of extinct core complexes extends away from the axis for at least 100 km. Our observations reveal the topographic characteristics of actively forming core complexes and their evolution from initiation within the axial valley floor to maturity and eventual inactivity. Within the surrounding region there is a strong correlation between detachment fault morphology at the ridge axis and high rates of hydroacoustically recorded earthquake seismicity. Preliminary examination of seismicity and seafloor morphology farther north along the Mid-Atlantic Ridge suggests that active detachment faulting is occurring in many segments and that detachment faulting is more important in the generation of ocean crust at this slow-spreading ridge than previously suspected.

  12. Quantitative Assessment of Potentially Active Faults in Oklahoma Utilizing Detailed Information on In Situ Stress Orientation and Relative Magnitude

    NASA Astrophysics Data System (ADS)

    Walsh, R.; Zoback, M. D.

    2015-12-01

    Over the past six years, the earthquake rate in the central and eastern U.S. has increased markedly, and is related to fluid injection. Nowhere has seismicity increased more than in Oklahoma, where large volumes of saline pore water are co-produced with oil and gas, then injected into deeper sedimentary formations. These deeper formations appear to be in hydraulic communication with potentially active faults in crystalline basement, where nearly all the earthquakes are occurring. Although the majority of the recent earthquakes have posed little danger to the public, the possibility of triggering damaging earthquakes on potentially active basement faults cannot be discounted. To understand probability of slip on a given fault, we invert for stresses from the hundreds of M4+ events in Oklahoma for which moment tensors have been made. We then resolve these stresses, while incorporating uncertainties, on the faults from the preliminary Oklahoma fault map. The result is a probabilistic understanding of which faults are most likely active and best avoided.

  13. Reconnaissance Observations of Newly Identified Active Faults and Their Relationship to Evolution of the Mount McKinley Restraining Bend, Denali National Park, Alaska

    NASA Astrophysics Data System (ADS)

    Bemis, S. P.; Benowitz, J.

    2012-12-01

    The processes of restraining bend formation and evolution along strike-slip faults remain poorly understood. Although connections between exhumation, fault displacement, and structural geometry are difficult to establish, long-lived active faults contribute to rock uplift, partition strain, and provide insight into the crustal stresses that result from the complex geometry of a restraining bend. The highest topography in North America, Mount McKinley (also known as Denali), is closely associated with an ~17 degree bend in the Denali fault and the region exhibits structural, geomorphic, and thermochronologic constraints on the late Cenozoic evolution of the Mount McKinley restraining bend. As a component of our investigation into the initiation and growth of this restraining bend, we are mapping the bedrock and surficial geology along the north side of the restraining bend to document evidence for Quaternary-active faults. Previous workers only document one active fault, the East Fork fault, north of the Denali fault. The lack of active faults is surprising due to the high rate of regional seismicity. Our initial studies recognize several previously undocumented faults that offset late Pleistocene glacial moraines and fluvial/alluvial surfaces, indicating active deformation is more widely spread than previously recognized and illustrating distinct patterns of strain accommodation. The East Fork fault and nearby structures occur east of the apex of the restraining bend and are sub-vertical with characteristically south-side-down displacements. Faults occurring adjacent to, and west of, the restraining bend apex are all south-side-up thrust faults and appear to have accommodated a significant component of the modern topographic development on the north side of the Denali fault. Future work will target the structural geometry and slip rates of these faults in order to determine how this restraining bend has evolved to the present configuration, and these results will

  14. Investigating active faulting in the south-central Chilean forearc by local seismicity and moment tensor inversions

    NASA Astrophysics Data System (ADS)

    Rietbrock, A.; Bohm, M.; Echtler, H.; Melnick, D.; Bruhn, C.; Bataille, K.

    2004-12-01

    The seismological ISSA experiment is giving a detailed insight into the seismicity distribution of southern Chile, where major earthquakes (M>8) have repeatedly ruptured the surface, involving vertical offsets of several meters. During a nearly 5-month observation period in 1999 and 2000 a temporary seismic network recorded approximately 350 local earthquakes. Two localized areas, North and South of the Arauco peninsula, showed a very high seismic activity in and above the interplate seismic zone of the Nazca-South America convergent margin. We used a double-difference relocation technique to obtain detailed images of the seismicity distribution in these areas. We also determined fault plane solutions to interpret the observed alignment of earthquakes hypocenters. Due to the low signal to noise ratio reliable first motion reading were difficult to achieve, which only very few clear readings. To overcome this problem we used moment tensor inversions to estimate reliable source mechanisms. However, for small magnitude earthquakes (<5) the biggest obstacle is the alignment of synthetic and observed waveforms. Inverting only for the amplitude spectrum, and therefore dropping the information in the phase spectrum can mostly circumvent the alignment problem. The two clusters investigated show high waveform correlation coefficients for most of the earthquakes indicating that possibly changes in fluid pressure can be responsible for triggering the events. After relocation most of the hypocenters in each of the two clusters align on a eastward dipping fault. Source mechanisms obtained indicate thrust faulting, where one of the possible fault planes aligns with the steep eastward dipping fault based on the seismicity distribution. These faults are reaching down to the top of the seismogenic zone and may serve as pathways for ascending fluids released in the subduction process. Active crustal-scale faulting below and active uplift of the coast account for active tectonic

  15. Late Pliocene To Pleistocene Tectonic Activity In SW Portugal: The S.Teotónio-Aljezur- Sinceira Fault System And Evidence For Coastal Uplift

    NASA Astrophysics Data System (ADS)

    Figueiredo, P.; Cabral, J.; Rockwell, T.

    2008-12-01

    mainly by Mesozoic limestones and exhibits a generally lower topography accented by karstic morphology. In both areas, little work has been done to map the sequence of marine terraces, nor to determine their ages, although the majority of them are likely Pleistocene. The highest raised marine deposits reach an altitude of 370 m ~13 km inland and may be as old as Pliocene in age. Inland, the Säo Teotónio-Aljezur-Sinceira fault system (STASFS) extends NNE-SSW for 50 km, parallel and close to the southwest Portuguese coast, and controls the development of several small Cenozoic tectonic basins. It comprises onshore faults which may relate to the ongoing plate boundary deformation. This fault system expresses primarily sinistral strike-slip with a minor reverse component. Four cenozoic strike-slip basins occur along the STASFS, generally with lengths of less than 5 km and a maximum width of 1.5 km, filled with Miocene to Pleistocene sediments. In some areas, fault-related post-Pliocene vertical displacements of up to 100 m may have occurred, but generally they only reach a few tens of meters. This coastal region is therefore particularly appropriate for establishing the offshore-onshore link through a detailed neotectonic study of the active faults, including exploration with paleoseismological techniques, and the vertical deformation field using marine terraces as a reference frame.

  16. Paleoseismicity of the Ovindoli-Pezza fault, central Apennines, Italy: A history including a large, previously unrecorded earthquake in the Middle Ages (860-1300 A.D.)

    NASA Astrophysics Data System (ADS)

    Pantosti, Daniela; D'Addezio, Giuliana; Cinti, Francesca R.

    1996-03-01

    Geomorphic and trenching investigations along the Ovindoli-Pezza fault show that this normal fault is one of the major seismogenic faults in the central Apennines. We found clear geological evidence for three Holocene surface-faulting earthquakes on this fault: the most recent earthquake occurred in the Middle Ages between 860 and 1300 A.D., the penultimate occurred about 1900 B.C. or shortly after, and the oldest probably occurred between 3300 and 5000 B.C. Although the most recent surface faulting earthquake occurred during historical time, no evidence for it has been found in the historical record. Slip per event ranges between 2 and 3 m, and the length of the rupture is at least 12-20 km, suggesting M 6.5-7.0 for the paleoearthquakes. The dip-slip rate determined from trenching is 0.7-1.2 mm/yr and is consistent with the long-term slip rate of 0.9-2.5 mm/yr (lower values preferred) obtained from displaced geomorphic features. Trench data combined with long-term slip rate estimates suggest the recurrence interval is longer than a millennium and possibly as long as 3300 years. The time elapsed since the most recent earthquake is 700-1130 years. The seismic behavior of the Ovindoli-Pezza fault is consistent with other well-known seismogenic faults of the central and southern Apennines. The lack of mention or mislocation of the most recent event on the Ovindoli-Pezza fault in the historical record of the past two millennia should be attributed mainly to the unsettled cultural and social conditions and poor economic state that characterized the Middle Ages, especially in thinly populated regions such as the central Apennines. This example highlights an intrinsic limit of the historical data and raises the possibility that other regions considered "seismically quiet" on the basis of a long historical record may in reality have had large earthquakes that were not recorded.

  17. Flight elements: Fault detection and fault management

    NASA Technical Reports Server (NTRS)

    Lum, H.; Patterson-Hine, A.; Edge, J. T.; Lawler, D.

    1990-01-01

    Fault management for an intelligent computational system must be developed using a top down integrated engineering approach. An approach proposed includes integrating the overall environment involving sensors and their associated data; design knowledge capture; operations; fault detection, identification, and reconfiguration; testability; causal models including digraph matrix analysis; and overall performance impacts on the hardware and software architecture. Implementation of the concept to achieve a real time intelligent fault detection and management system will be accomplished via the implementation of several objectives, which are: Development of fault tolerant/FDIR requirement and specification from a systems level which will carry through from conceptual design through implementation and mission operations; Implementation of monitoring, diagnosis, and reconfiguration at all system levels providing fault isolation and system integration; Optimize system operations to manage degraded system performance through system integration; and Lower development and operations costs through the implementation of an intelligent real time fault detection and fault management system and an information management system.

  18. GeoBioScience: Red Wood Ants as Bioindicators for Active Tectonic Fault Systems in the West Eifel (Germany).

    PubMed

    Berberich, Gabriele; Schreiber, Ulrich

    2013-05-17

    In a 1.140 km² study area of the volcanic West Eifel, a comprehensive investigation established the correlation between red wood ant mound (RWA; Formica rufa-group) sites and active tectonic faults. The current stress field with a NW-SE-trending main stress direction opens pathways for geogenic gases and potential magmas following the same orientation. At the same time, Variscan and Mesozoic fault zones are reactivated. The results showed linear alignments and clusters of approx. 3,000 RWA mounds. While linear mound distribution correlate with strike-slip fault systems documented by quartz and ore veins and fault planes with slickensides, the clusters represent crosscut zones of dominant fault systems. Latter can be correlated with voids caused by crustal block rotation. Gas analyses from soil air, mineral springs and mofettes (CO₂, Helium, Radon and H₂S) reveal limiting concentrations for the spatial distribution of mounds and colonization. Striking is further the almost complete absence of RWA mounds in the core area of the Quaternary volcanic field. A possible cause can be found in occasionally occurring H₂S in the fault systems, which is toxic at miniscule concentrations to the ants. Viewed overall, there is a strong relationship between RWA mounds and active tectonics in the West Eifel.

  19. Mineral Reactions in Active Fault Strands of the SAFOD Borehole: Results from Mineralogical and U/Th Studies

    NASA Astrophysics Data System (ADS)

    Schleicher, A. M.; Ali, S.; Stute, M.; Torgersen, T.; van der Pluijm, B. A.; Warr, L. N.

    2009-12-01

    Mix-layered clay minerals are common in fault rocks, and their mineralization is strongly influenced by the surrounding environment. Based on detailed mineralogical and geochemical study of mudrock samples from the San Andreas Fault Observatory at Depth (SAFOD), phase 3, we present new TEM-XRD and U/Th results from bore hole depths of 3186.7 m to 3198.9 m, and 3294.9 m to 3313.5 m measured depth. These areas contain two actively creeping sections of the fault zone: Fault strand 10480 (~3194 m) and Fault strand 10830 (~3301 m). XRD analysis of the clay minerals in both fault strands show illite and illite-smectite (I-S) and chlorite dominating from 3186.7 m to 3196.3 m, and 3294.9 m to 3297 m measured depth. Samples containing increased chlorite-smectite (C-S) and corrensite (50:50 C-S) are mostly restricted to a well-defined interval in the center of the two fault strands between 3196.3 m to 3198.1 m, and 3297.5 to ~3305 m. Relatively high U/Th values in both creeping sections of the fault zone indicate that the presence of corrensite and chlorite is associated with reducing conditions during mineral formation, compared to more oxygenated adjacent rocks along the drill cores. TEM also shows serpentine minerals (chrysotile) especially in the fault centers at 3196.8 m and at 3297.5 m depth. These initially tubular phases are slightly flattened and oval in section with distinct strain features that reflect pre-faulting crystallization and subsequent ductile deformation within the fault zone. The C-S phases surrounding the chyrostile show no distinct deformation or subsequent alteration features. Chemical analyses show chlorite and C-S with a high Mg content, which indicates that their crystallization may have involved the destabilization of serpentine, providing Fe and Mg, whereas leaching of mica, feldspar and quartz from the wall-rock, is the probable source of Si and Al. This temporal sequence of reaction weakening suggests distinct changes in the fluid chemistry

  20. Frictional evolution, acoustic emissions activity, and off-fault damage in simulated faults sheared at seismic slip rates

    NASA Astrophysics Data System (ADS)

    Passelègue, François. X.; Spagnuolo, Elena; Violay, Marie; Nielsen, Stefan; Di Toro, Giulio; Schubnel, Alexandre

    2016-10-01

    We present a series of high-velocity friction tests conducted on Westerly granite, using the Slow to HIgh Velocity Apparatus (SHIVA) installed at Istituto Nazionale di Geofisica e Vulcanologia Roma with acoustic emissions (AEs) monitored at high frequency (4 MHz). Both atmospheric humidity and pore fluid (water) pressure conditions were tested, under effective normal stress σneff in the range 5-20 MPa and at target sliding velocities Vs in the range 0.003-3 m/s. Under atmospheric humidity two consecutive friction drops were observed. The first one is related to flash weakening, and the second one to the formation and growth of a continuous layer of melt in the slip zone. In the presence of fluid, a single drop in friction was observed. Average values of fracture energy are independent of effective normal stress and sliding velocity. However, measurements of elastic wave velocities on the sheared samples suggested that larger damage was induced for 0.1 < Vs<0.3 m/s. This observation is supported by AEs recorded during the test, most of which were detected after the initiation of the second friction drop, once the fault surface temperature was high. Some AEs were detected up to a few seconds after the end of the experiments, indicating thermal rather than mechanical cracking. In addition, the presence of pore water delayed the onset of AEs by cooling effects and by reducing of the heat produced, supporting the link between AEs and the production and diffusion of heat during sliding. Using a thermoelastic crack model developed by Fredrich and Wong (1986), we confirm that damage may be induced by heat diffusion. Indeed, our theoretical results predict accurately the amount of shortening and shortening rate, supporting the idea that gouge production and gouge comminution are in fact largely controlled by thermal cracking. Finally, we discuss the contribution of thermal cracking in the seismic energy balance. In fact, while a dichotomy exists in the literature regarding

  1. The interplay between fault-fracture networks activity, fluid flow and mineralization in the Andes: A case study in the Tolhuaca geothermal system, southern Chile

    NASA Astrophysics Data System (ADS)

    Sanchez, P.; Perez-Flores, P.; Reich, M.; Arancibia, G.; Cembrano, J. M.

    2013-05-01

    The nature of the interplay between active tectonics and fluid flow is a key feature to better understand the chemical evolution of fluids in geothermal and hydrothermal systems. The prominent hydrothermal, tectonic and volcanic activity of the Southern Andes volcanic zone (SVZ) makes it one of the best natural laboratories to address this issue. In the northern termination of the Liquiñe-Ofqui Fault System (LOFS), tectonic and volcanic processes interact to define the geothermal field of Tolhuaca. The objective of our current research is to assess the nature of the interplay between brittle deformation and chemical evolution of fluids and mineral paragenesis. Tol-1 is a vertical 1.080 m deep borehole which could yield relevant information regarding the evolution of the Tolhuaca geothermal system. The methodology to achieve our objective includes the structural and geochemical analysis of oriented faults, fault-veins and veins -former pathways- in the core. Structural mapping at the regional scale will help to identify the main structural system, which accommodates the regional stresses, and promotes fluid migration, accumulation and arrest. Fluid inclusions analysis by microthermometry, LA-ICP-MS and Raman spectroscopy will allow a better understanding of the feedback between the fluid flow episodes and the mineralization. More than 120 structural measurements of faults, veins and fault-veins were performed (strike, dip, rake -when available-). Forty seven samples were taken for thin & fluid inclusions sections. Detailed mapping of structures including dip and kinematic indicators from mineral sealing was synthesized in a structural log of Tol-1 core. Our preliminary results show that there is a strong correlation between abundance of structures and rock type. Lava intervals exhibit more intense fracturing and veining than tuff and volcaniclastic intervals. In the upper 300 m of the core, structures are primarily steeply dipping with a dominant normal sense of

  2. Recent Fault Activity in the 1886 Charleston, South Carolina Earthquake Epicentral Area and its Relation to Buried Structures

    NASA Astrophysics Data System (ADS)

    Pratt, T. L.; Shah, A. K.; Horton, J. W., Jr.; Chapman, M. C.; Beale, J.

    2014-12-01

    Charleston, is interpreted based on disruptions of magnetic anomalies to align with the greatest earthquake deformation observed along 3 railroad lines, including lateral offsets of the tracks and NE-trending surface fissures. These observations are consistent with two NE-trending faults rupturing during the 1886 earthquake.

  3. Active faulting in the frontal Rif Cordillera (Fes region, Morocco): Constraints from GPS data

    NASA Astrophysics Data System (ADS)

    Chalouan, Ahmed; Gil, Antonio J.; Galindo-Zaldívar, Jesús; Ahmamou, M.'Fedal; Ruano, Patricia; de Lacy, Maria Clara; Ruiz-Armenteros, Antonio Miguel; Benmakhlouf, Mohamed; Riguzzi, Federica

    2014-07-01

    The southern Rif cordillera front, between Fes and Meknes, is formed by the Prerif Ridges, which constitute a thrust and fold belt, in contact with the Saïss foreland basin. Geological evidence and regional GPS network data support recent and active tectonics of this Alpine cordillera, with a top-to-the-S-SW motion with respect to stable Africa. A local non-permanent GPS network was installed in 2007 around Fes to constrain the present-day activity of the mountain front. Six GPS sites are located in the Prerif mountain front (jbel Thratt and jbel Zalarh), the Saïss basin and the foreland constituted by the tabular Middle Atlas. Measurements of the GPS network in 2007, 2009 and 2012, over a five year span, seem to indicate that this region is tectonically active and is subjected to significant horizontal motions: (i) a regional displacement toward the SW with respect to stable Africa, showing an average rate of 2 mm/yr; (ii) a southwestward convergent motion between the jbel Thratt with respect to the Saïss basin and the eastern Zalarh ridge, with an average rate of about 4 mm/yr; and (iii) moderate NNE-SSW divergent dextral motion between the Saïss basin and the northern front of the tabular Middle Atlas with an average rate of about 1-2 mm/yr. The regional southwestward motion is related to the activity of the NE-SW sinistral North Middle Atlas-Kert fault zone, which follows the Moroccan Hot Line. Convergence between the Prerif ridges, located at the southern edge of the Rif, and the Saïss basin is accommodated by ENE-WSW striking northward dipping reverse sinistral faults and south vergent folds. In addition, increasing deformation toward the western ridges is in agreement with the stepped mountain front and the development of the arched structures of the Prerif ridges. Normal faults located south of the Saïss basin are responsible for local extension. Whereas the most active deformation occurs in the southern front of the jbel Thratt near Fes, the Sa

  4. Earthquakes, active faults, and geothermal areas in the imperial valley, california.

    PubMed

    Hill, D P; Mowinckel, P; Peake, L G

    1975-06-27

    A dense seismograph network in the Imperial Valley recorded a series of earthquake swarms along the Imperial and Brawley faults and a diffuse pattern of earthquakes along the San Jacinto fault. Two known geothermal areas are closely associated with these earthquake swarms. This seismicity pattern demonstrates that seismic slip is occurring along both the Imperial-Brawley and San Jacinto fault systems.

  5. Active faulting in Raghunandan Anticline, NE Bengal Basin, implications for future earthquake hazards

    NASA Astrophysics Data System (ADS)

    Ahsan, A.; Kali, E.; Coudurier Curveur, A.; van der Woerd, J.; Tapponnier, P.; Alam, A. K.; Ildefonso, S.; Banerjee, P.; Dorbath, C.

    2015-12-01

    The Bengal basin is situated in a complex tectonic zone where the Indian-Eurasian Plates and Indian-Burmese Plates are colliding. This region is known for some of the largest intra-continental seismic events of the last 500 years, the 1548 Bengal earthquake of magnitude M>8?, the 1762 Arakan earthquake of magnitude M>8?, the 1897 Shillong earthquakes of magnitude Ms 8.7, the 1918 Srimangal earthquake of magnitude Ms 7.6 and the 1950 Assam earthquake of magnitude Mw 8.6. The source faults of these events and whether these large earthquakes occurred on faults that reached the surface or reminded blind remain controversial. The Bengal basin still needs to be better understood in terms of active faulting and seismicity. The Eastern boundary of Bengal basin is marked by numerous NS trending folds of the Indo-Burma Ranges. We focused on the Raghunandan Anticline, NE Bengal basin, a broad, asymmetric, growing ramp anticline, steep west-facing front and bounded westwards by a steep tectonic scarp truncating gently east dipping Quaternary sandstone beds. The scarp morphology is suggestive of a still preserved co-seismic free face above a colluvial wedge. We carried out more than 20 topographic profiles to document the precise height and shape of this 12-15 m high scarp (above alluvial surface) and to survey a set of uplifted alluvial terraces located along the Shahapur River behind the scarp. The analysis of the topographic profiles around the Shajibazar area reveals the presence of 5 alluvial terraces hanging 3 m to 19 m above Shahapur River bed. T1 and T2 terraces are the best-preserved terraces on both sides of the Shahapur River. C14 and Be 10 ages allow to date the lowest abandonned terrace and to estimate the uplift rate of this area.

  6. Comparison between different methodologies for detecting radon in soil along an active fault: the case of the Pernicana fault system, Mt. Etna (Italy).

    PubMed

    Giammanco, S; Immè, G; Mangano, G; Morelli, D; Neri, M

    2009-01-01

    Three different methodologies were used to measure Radon ((222)Rn) in soil, based on both passive and active detection system. The first technique consisted of solid-state nuclear track detectors (SSNTD), CR-39 type, and allowed integrated measurements. The second one consisted of a portable device for short time measurements. The last consisted of a continuous measurement device for extended monitoring, placed in selected sites. Soil (222)Rn activity was measured together with soil Thoron ((220)Rn) and soil carbon dioxide (CO(2)) efflux, and it was compared with the content of radionuclides in the rocks. Two different soil-gas horizontal transects were investigated across the Pernicana fault system (NE flank of Mount Etna), from November 2006 to April 2007. The results obtained with the three methodologies are in a general agreement with each other and reflect the tectonic settings of the investigated study area. The lowest (222)Rn values were recorded just on the fault plane, and relatively higher values were recorded a few tens of meters from the fault axis on both of its sides. This pattern could be explained as a dilution effect resulting from high rates of soil CO(2) efflux. Time variations of (222)Rn activity were mostly linked to atmospheric influences, whereas no significant correlation with the volcanic activity was observed. In order to further investigate regional radon distributions, spot measurements were made to identify sites having high Rn emissions that could subsequently be monitored for temporal radon variations. SSNTD measurements allow for extended-duration monitoring of a relatively large number of sites, although with some loss of temporal resolution due to their long integration time. Continuous monitoring probes are optimal for detailed time monitoring, but because of their expense, they can best be used to complement the information acquired with SSNTD in a network of monitored sites.

  7. Coseismic uplift and fault model of marine active faults in 1729 AD revealed by fossilized intertidal sessile organisms along the northern coast of the Noto Peninsula, central Japan

    NASA Astrophysics Data System (ADS)

    Hamada, M.; Hiramatsu, Y.; Oda, M.; Yamaguchi, H.

    2015-12-01

    The Noto Peninsula is located in the backarc region of southwest Japan and is characterized by geomorphologic features formed by active tectonics and glacial eustasy through the Quaternary. Pleistocene marine terraces along the northern coast of the Noto Peninsula indicate uplift in the coastal area through the late Quaternary (Ota and Hirakawa, 1979). Recently, an active fault zone on the seafloor off the coast was found and was divided into four segments, Monzen-oki, Saruyama-oki, Wajima-oki, and Suzu-oki, from west to east (Inoue and Okamura, 2010). We investigated vertical displacement along the coast using intertidal sessile organisms at nine sites on the rocky coast. We measured the height of fossilized Pomatoleios kraussii by GPS surveying together with a sea-level change curve, and dated them using the AMS 14C method. The vertical displacements and dates at the sites implied that coastal uplift occurred along 20 km of coastline, corresponding to the Wajima-oki segment zone, and most likely between 1600 and 1800 AD. This is coincident with seismic damage in this area in 1729 AD recorded in historical documents. We constructed a fault model with three rectangular faults in a homogeneous elastic half-space and estimated the optimal net slip and rake by a non-linear inversion method (Matsu'ura and Hasegawa, 1987). The best fit to the estimated vertical displacements is provided by a net slip of 1.8 m with a rake of 90° for the western fault plane and a net slip of 0.6 m with a rake of 90° for the center and the eastern fault planes. The moment magnitude (Mw) calculated from these parameters with a rigidity of 30 GPa is 6.6. We compared the elevation distribution of the former shorelines based on coastal terraces and the 1729 earthquake uplifts. Assuming that the coastal uplift is caused by the cumulative crustal deformation produced by the same size event as the 1729 earthquake, the average recurrence interval of the events is estimated to be 1700 years.

  8. Sea-Floor Spreading and Transform Faults

    ERIC Educational Resources Information Center

    Armstrong, Ronald E.; And Others

    1978-01-01

    Presents the Crustal Evolution Education Project (CEEP) instructional module on Sea-Floor Spreading and Transform Faults. The module includes activities and materials required, procedures, summary questions, and extension ideas for teaching Sea-Floor Spreading. (SL)

  9. Mantle-derived CO2 migration along active faults within an extensional basin margin (Fiumicino, Rome, Italy)

    NASA Astrophysics Data System (ADS)

    Bigi, S.; Beaubien, S. E.; Ciotoli, G.; D'Ambrogi, C.; Doglioni, C.; Ferrante, V.; Lombardi, S.; Milli, S.; Orlando, L.; Ruggiero, L.; Tartarello, M. C.; Sacco, P.

    2014-12-01

    Fluid migration along faults can be highly complex and spatially variable, with the potential for channeled flow, accumulation in capped porous units, fault cross-flow, lateral migration along strike, or complete sealing. Extensional basin margins can be important for such migration, given the associated crustal thinning and decompression that takes place combined with potential geothermal or mantle gas sources. One such example is near the urban area of Rome, situated along the active extensional continental margin of the Tyrrhenian back arc basin and surrounded by Middle-Upper Pleistocene K-rich and arc-related volcanoes. Recent research activities in the area around Fiumicino, a town 25 km to the west of Rome, has highlighted the close spatial link between degassing CO2 and the faults that provide the necessary vertical migration pathways. In particular, detailed soil gas and gas flux surveys have highlighted the release at surface of large volumes of asthenospheric mantle CO2 in correspondence with normal faults observed in a new seismic reflection profile acquired along the Tiber River. Detailed reconstruction of the Pleistocene-Holocene stratigraphy of the area dates fault activity from 20,000 to 9000 years BP. It is proposed that the gas migrates preferentially along the cataclastic tectonic breccias of the faults until it encounters recent, unconsolidated sediments; porous units within this shallow stratigraphy act as temporary secondary traps for the leaking gas, with local gas release at the ground surface occurring where the sealing of the overlying aquitards has been compromised. Degassing and active faults confirm the extensional tectonics affecting the area and the geodynamic scenario of a mantle wedge beneath the western Apennines, associated with ongoing W-directed subduction. Moreover, degassing highlights the potential geochemical and seismic risks for the highly populated urban areas near Rome.

  10. Uranium concentrations and 234U/238U activity ratios in fault-associated groundwater as possible earthquake precursors

    NASA Astrophysics Data System (ADS)

    Finkel, R. C.

    In order to assess the utility of uranium isotopes as fluid phase earthquake precursors, uranium concentrations and 234U/238U activity ratios have been monitored on a monthly or bimonthly basis in water from 24 wells and springs associated with Southern California fault zones. Uranium concentrations vary from 0.002 ppb at Indian Canyon Springs on the San Jacinto fault to 8.3 ppb at Lake Hughes well on the San Andreas fault in the Palmdale area. 234U/238U activity ratios vary from 0.88 at Agua Caliente Springs on the Elsinore fault to 5.4 at Niland Slab well on the San Andreas fault in the Imperial Valley. There was one large earthquake in the study area during 1979, the 15 October 1979 M=6.6 Imperial Valley earthquake. Correlated with this event, uranium concentrations varied by a factor of more than 60 and activity ratios by a factor of 3 at the Niland Slab site, about 70 km from the epicenter. At the other sites monitored, uranium concentrations varied in time, but with no apparent pattern, while uranium activity ratios remained essentially constant throughout the monitoring period.

  11. Physical mechanism of the vertical electric field generation over active tectonic faults

    NASA Astrophysics Data System (ADS)

    Pulinets, S. A.

    2009-09-01

    The concept of the Global Electric Circuit (GEC) provides an explanation of the existence of a vertical atmospheric electric field and coupling between the ground and ionosphere. Presently, ionospheric physics pays more attention to electric fields and coupling processes in the polar and auroral regions, whereas in other areas the potential difference between the ground and ionosphere usually is not taken into account. Regional processes exist, however, that are able to significantly affect the GEC parameters and through modification of the ionospheric potential to create plasma density irregularities of different scales within the ionosphere. One such source of ionosphere modification is air ionization in the vicinity of active tectonic faults, which takes place due to increased radon emanation. This paper considers the process of local modification of the GEC and corresponding ionospheric variability due to tectonic activity.

  12. Consequences of the presence of a weak fault on the stress and strain within an active margin

    NASA Astrophysics Data System (ADS)

    Conin, M.; Henry, P.; Godard, V.; Bourlange, S.

    2009-12-01

    Accreting margins often display an outer thrust and fold belt and an inner forearc domain overlying the subduction plate. Assuming that this overlying material behaves as Coulomb material, the outer wedge and the inner wedge are classically approximated as a critical state and a stable state Coulomb wedge, respectively. Critical Coulomb wedge theory can account for the transition from wedge to forearc. However, it cannot be used to determine the state of stress in the transition zone, nor the consequences of a discontinuity within the margin. The presence of a discontinuity such as a splay fault having a low effective friction coefficient should affect the stress state within the wedge, at least locally around the splay fault. Moreover, the effective friction coefficient of the seismogenic zone is expected to vary during the seismic cycle, and this may influence the stability of the Coulomb wedges. We use the ADELI finite element code (Chery and Hassani, 2000) to model the quasi-static stress and strain of a decollement and splay fault system, within a two dimensional elasto-plastic wedge with Drucker-Prager rheology. The subduction plane, the basal decollement of the accretionary wedge and the splay fault are modeled with contact elements. The modeled margin comprises an inner and an outer domain with distinct tapers and basal friction coefficients. For a given splay fault geometry, we evaluate the friction coefficient threshold for splay fault activation as a function of the basal friction coefficients, and examine the consequences of motion along the splay fault on stress and strain within the wedge and on the surface slope at equilibrium. Friction coefficients are varied in time to mimic the consequence of the seismic cycle on the static stress state and strain distribution. Results show the possibility of coexistence of localized extensional regime above the splay fault within a regional compressional regime. Such coexistence is consistent with stress

  13. Active crustal deformation of the El Salvador Fault Zone (ESFZ) using GPS data: Implications in seismic hazard assessment

    NASA Astrophysics Data System (ADS)

    Staller, Alejandra; Benito, Belen; Jesús Martínez-Díaz, José; Hernández, Douglas; Hernández-Rey, Román; Alonso-Henar, Jorge

    2014-05-01

    El Salvador, Central America, is part of the Chortis block in the northwestern boundary of the Caribbean plate. This block is interacting with a diffuse triple junction point with the Cocos and North American plates. Among the structures that cut the Miocene to Pleistocene volcanic deposits stands out the El Salvador Fault Zone (ESFZ): It is oriented in N90º-100ºE direction, and it is composed of several structural segments that deform Quaternary deposits with right-lateral and oblique slip motions. The ESFZ is seismically active and capable of producing earthquakes such as the February 13, 2001 with Mw 6.6 (Martínez-Díaz et al., 2004), that seriously affected the population, leaving many casualties. This structure plays an important role in the tectonics of the Chortis block, since its motion is directly related to the drift of the Caribbean plate to the east and not with the partitioning of the deformation of the Cocos subduction (here not coupled) (Álvarez-Gómez et al., 2008). Together with the volcanic arc of El Salvador, this zone constitutes a weakness area that allows the motion of forearc block toward the NW. The geometry and the degree of activity of the ESFZ are not studied enough. However their knowledge is essential to understand the seismic hazard associated to this important seismogenic structure. For this reason, since 2007 a GPS dense network was established along the ESFZ (ZFESNet) in order to obtain GPS velocity measurements which are later used to explain the nature of strain accumulation on major faults along the ESFZ. The current work aims at understanding active crustal deformation of the ESFZ through kinematic model. The results provide significant information to be included in a new estimation of seismic hazard taking into account the major structures in ESFZ.

  14. Active normal fault network of the Apulian Ridge (Eastern Mediterranean Sea) imaged by multibeam bathymetry and seismic data

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    The Apulian ridge (North-eastern Ionian margin - Mediterranean Sea) is formed by thick cretaceous carbonatic sequences and discontinuous tertiary deposits crosscut by a NNW-SSE penetrative normal fault system and is part of the present foreland system of both the Apennine to the west and the Hellenic arc to the east. The geometry, age, architecture and kinematics of the fault network were investigated integrating data of heterogeneous sources, provided by previous studies: regional scale 2D seismics and three wells collected by oil companies from the '60s to the '80s, more recent seismics collected during research projects in the '90s, very high resolution seismic (VHRS - Sparker and Chirp-sonar data), multi-beam echosounder bathymetry and results from sedimentological and geo-chronological analysis of sediment samples collected on the seabed. Multibeam bathymetric data allowed in particular assessing the 3D continuity of structures imaged in 2D seismics, thanks to the occurrence of continuous fault scarps on the seabed (only partly reworked by currents and covered by landslides), revealing the vertical extent and finite displacement associated to fault scarps. A penetrative network of relatively small faults, always showing a high dip angle, composes the NNW-SSE normal fault system, resulting in frequent relay zones, which are particularly well imaged by seafloor geomorphology. In addition, numerous fault scarps appear to be roughly coeval with quaternary submarine mass-wasting deposits colonised by Cold-Water Corals (CWC). Coral colonies, yielding ages between 11 and 14 kA, develop immediately on top of late Pleistocene mass-wasting deposits. Mutual cross-cutting relationships have been recognized between fault scarps and landslides, indicating that, at least in places, these features may be coeval. We suppose that fault activity lasted at least as far as the Holocene-Pleistocene boundary and that the NNW-SSW normal fault network in the Apulian Plateau can be

  15. Slip sense inversion on active strike-slip faults in southwest Japan and its implications for Cenozoic tectonic evolution

    NASA Astrophysics Data System (ADS)

    Maruyama, Tadashi; Lin, Aiming

    2004-05-01

    Analyses of deflected river channels, offset of basement rocks, and fault rock structures reveal that slip sense inversion occurred on major active strike-slip faults in southwest Japan such as the Yamasaki and Mitoke fault zones and the Median Tectonic Line (MTL). Along the Yamasaki and Mitoke fault zones, small-size rivers cutting shallowly mountain slopes and Quaternary terraces have been deflected sinistrally, whereas large-size rivers which deeply incised into the Mio-Pliocene elevated peneplains show no systematically sinistral offset or complicated hairpin-shaped deflection. When the sinistral offsets accumulated on the small-size rivers are restored, the large-size rivers show residual dextral deflections. This dextral offset sense is consistent with that recorded in the pre-Cenozoic basement rocks. S-C fabrics of fault gouge and breccia zone developed in the active fault zones show sinistral shear sense compatible with earthquake focal mechanisms, whereas those of the foliated cataclasite indicate a dextral shear sense. These observations show that the sinistral strike-slip shear fabrics were overprinted on dextral ones which formed during a previous deformation phase. Similar topographic and geologic features are observed along the MTL in the central-eastern part of the Kii Peninsula. Based on these geomorphological and geological data, we infer that the slip sense inversion occurred in the period between the late Tertiary and mid-Quaternary period. This strike-slip inversion might result from the plate rearrangement consequent to the mid-Miocene Japan Sea opening event. This multidisciplinary study gives insight into how active strike-slip fault might evolves with time.

  16. 3D Modelling of Seismically Active Parts of Underground Faults via Seismic Data Mining

    NASA Astrophysics Data System (ADS)

    Frantzeskakis, Theofanis; Konstantaras, Anthony

    2015-04-01

    During the last few years rapid steps have been taken towards drilling for oil in the western Mediterranean sea. Since most of the countries in the region benefit mainly from tourism and considering that the Mediterranean is a closed sea only replenishing its water once every ninety years careful measures are being taken to ensure safe drilling. In that concept this research work attempts to derive a three dimensional model of the seismically active parts of the underlying underground faults in areas of petroleum interest. For that purpose seismic spatio-temporal clustering has been applied to seismic data to identify potential distinct seismic regions in the area of interest. Results have been coalesced with two dimensional maps of underground faults from past surveys and seismic epicentres, having followed careful reallocation processing, have been used to provide information regarding the vertical extent of multiple underground faults in the region of interest. The end product is a three dimensional map of the possible underground location and extent of the seismically active parts of underground faults. Indexing terms: underground faults modelling, seismic data mining, 3D visualisation, active seismic source mapping, seismic hazard evaluation, dangerous phenomena modelling Acknowledgment This research work is supported by the ESPA Operational Programme, Education and Life Long Learning, Students Practical Placement Initiative. References [1] Alves, T.M., Kokinou, E. and Zodiatis, G.: 'A three-step model to assess shoreline and offshore susceptibility to oil spills: The South Aegean (Crete) as an analogue for confined marine basins', Marine Pollution Bulletin, In Press, 2014 [2] Ciappa, A., Costabile, S.: 'Oil spill hazard assessment using a reverse trajectory method for the Egadi marine protected area (Central Mediterranean Sea)', Marine Pollution Bulletin, vol. 84 (1-2), pp. 44-55, 2014 [3] Ganas, A., Karastathis, V., Moshou, A., Valkaniotis, S., Mouzakiotis

  17. Holocene faulting in the western Basin and Range, California

    SciTech Connect

    Bryant, W.A. . Div. of Mines and Geology)

    1993-04-01

    Principal late Quaternary faults in the Basin and Range Geomorphic Province of eastern and northeastern California were evaluated for evidence of Holocene surface fault rupture as part of DMG's Fault Evaluation and Zoning Project. Those faults considered to have been active in Holocene time were zoned for special studies in order to mitigate surface fault rupture hazard as authorized by the Alquist-Priolo Special Studies Zones Act of 1972. Thirty-seven faults or fault zones were evaluated from the southern Sierra Nevada east to Death Valley and north to Surprise Valley. About 70% of these faults have evidence of Holocene displacement. Slip-rates for 20 faults have been determined by others or were estimated during this study. It is difficult to categorize slip-rates in this region because fault zones often are characterized by a complex history of both right-lateral strike-slip (rlss) and normal dip-slip displacement include the Death Valley, Deep Springs, Genoa, Hilton Creek, Honey Lake, Owens Valley, and Panamint Valley faults. All but 2 of these faults (Deep Springs and Genoa) have correspondingly high slip-rates [>=] 2mm/yr. The Death Valley, Honey Lake, Owens Valley, and Panamint Valley faults are characterized primarily by rlss displacement; the other 3 faults have predominantly normal displacement. Most of the faults considered to have primarily vertical displacement are characterized by maximum vertical slip-rates less than 1mm/yr. Range-front faults with maximum vertical slip-rates [>=]1mm/yr include the Genoa, Hilton Creek, Mono Lake, Round Valley, Surprise Valley, and White Mountains faults.

  18. Transition from collision to subduction in Western Greece: the Katouna-Stamna active fault system and regional kinematics

    NASA Astrophysics Data System (ADS)

    Pérouse, E.; Sébrier, M.; Braucher, R.; Chamot-Rooke, N.; Bourlès, D.; Briole, P.; Sorel, D.; Dimitrov, D.; Arsenikos, S.

    2016-06-01

    Transition from subduction to collision occurs in Western Greece and is accommodated along the downgoing plate by the Kefalonia right-lateral fault that transfers the Hellenic subduction front to the Apulian collision front. Here we present an active tectonic study of Aitolo-Akarnania (Western Greece) that highlights how such a transition is accommodated in the overriding plate. Based on new multi-scale geomorphic and tectonic observations, we performed an accurate active fault trace mapping in the region, and provide evidence for active normal and left-lateral faulting along the Katouna-Stamna Fault (KSF), a 65-km-long NNW-striking fault system connecting the Amvrakikos Gulf to the Patras Gulf. We further show that the Cenozoic Hellenide thrusts located west of the KSF are no longer active, either in field observation or in GPS data, leading us to propose that the KSF forms the northeastern boundary of a rigid Ionian Islands-Akarnania Block (IAB). Cosmic ray exposure measurements of 10Be and 36Cl were performed on a Quaternary alluvial fan offset along the KSF (~50 m left-lateral offset). A maximum abandonment age of ~12-14 ka for the alluvial fan surface can be determined, giving an estimated KSF minimum geological left-lateral slip rate of ~4 mm year-1, in agreement with high GPS slip rates (~10 mm year-1). Despite this high slip rate, the KSF is characterized by subdued morphological evidence of tectonic activity, a gypsum-breccia bedrock and a low level of seismicity, suggesting a dominantly creeping behavior for this fault. Finally, we discuss how the IAB appears to have been progressively individualized during the Pleistocene (younger than ~1.5 Ma).

  19. The 2013 earthquake swarm in Helike, Greece: seismic activity at the root of old normal faults

    NASA Astrophysics Data System (ADS)

    Kapetanidis, V.; Deschamps, A.; Papadimitriou, P.; Matrullo, E.; Karakonstantis, A.; Bozionelos, G.; Kaviris, G.; Serpetsidaki, A.; Lyon-Caen, H.; Voulgaris, N.; Bernard, P.; Sokos, E.; Makropoulos, K.

    2015-09-01

    The Corinth Rift in Central Greece has been studied extensively during the past decades, as it is one of the most seismically active regions in Europe. It is characterized by normal faulting and extension rates between 6 and 15 mm yr-1 in an approximately N10E° direction. On 2013 May 21, an earthquake swarm was initiated with a series of small events 4 km southeast of Aigion city. In the next days, the seismic activity became more intense, with outbursts of several stronger events of magnitude between 3.3 and 3.7. The seismicity migrated towards the east during June, followed by a sudden activation of the western part of the swarm on July 15th. More than 1500 events have been detected and manually analysed during the period between 2013 May 21 and August 31, using over 15 local stations in epicentral distances up to 30 km and a local velocity model determined by an error minimization method. Waveform similarity-based analysis was performed, revealing several distinct multiplets within the earthquake swarm. High-resolution relocation was applied using the double-difference algorithm HypoDD, incorporating both catalogue and cross-correlation differential traveltime data, which managed to separate the initial seismic cloud into several smaller, densely concentrated spatial clusters of strongly correlated events. Focal mechanism solutions for over 170 events were determined using P-wave first motion polarities, while regional waveform modelling was applied for the calculation of moment tensors for the 18 largest events of the sequence. Selected events belonging to common spatial groups were considered for the calculation of composite mechanisms to characterize different parts of the swarm. The solutions are mainly in agreement with the regional NNE-SSW extension, representing typical normal faulting on 30-50° north-dipping planes, while a few exhibit slip in an NNE-SSW direction, on a roughly subhorizontal plane. Moment magnitudes were calculated by spectral analysis

  20. Influence of fault trend, fault bends, and fault convergence on shallow structure, geomorphology, and hazards, Hosgri strike-slip fault, offshore central California

    NASA Astrophysics Data System (ADS)

    Johnson, S. Y.; Watt, J. T.; Hartwell, S. R.

    2012-12-01

    We mapped a ~94-km-long portion of the right-lateral Hosgri Fault Zone from Point Sal to Piedras Blancas in offshore central California using high-resolution seismic reflection profiles, marine magnetic data, and multibeam bathymetry. The database includes 121 seismic profiles across the fault zone and is perhaps the most comprehensive reported survey of the shallow structure of an active strike-slip fault. These data document the location, length, and near-surface continuity of multiple fault strands, highlight fault-zone heterogeneity, and demonstrate the importance of fault trend, fault bends, and fault convergences in the development of shallow structure and tectonic geomorphology. The Hosgri Fault Zone is continuous through the study area passing through a broad arc in which fault trend changes from about 338° to 328° from south to north. The southern ~40 km of the fault zone in this area is more extensional, resulting in accommodation space that is filled by deltaic sediments of the Santa Maria River. The central ~24 km of the fault zone is characterized by oblique convergence of the Hosgri Fault Zone with the more northwest-trending Los Osos and Shoreline Faults. Convergence between these faults has resulted in the formation of local restraining and releasing fault bends, transpressive uplifts, and transtensional basins of varying size and morphology. We present a hypothesis that links development of a paired fault bend to indenting and bulging of the Hosgri Fault by a strong crustal block translated to the northwest along the Shoreline Fault. Two diverging Hosgri Fault strands bounding a central uplifted block characterize the northern ~30 km of the Hosgri Fault in this area. The eastern Hosgri strand passes through releasing and restraining bends; the releasing bend is the primary control on development of an elongate, asymmetric, "Lazy Z" sedimentary basin. The western strand of the Hosgri Fault Zone passes through a significant restraining bend and

  1. Development of a Detailed Stress Map of Oklahoma for Avoidance of Potentially Active Faults When Siting Wastewater Injection Wells

    NASA Astrophysics Data System (ADS)

    Alt, R. C., II; Zoback, M. D.

    2014-12-01

    We report progress on a project to create a detailed map of in situ stress orientations and relative magnitudes throughout the state of Oklahoma. It is well known that the past 5 years has seen a remarkable increase in seismicity in much of the state, potentially related to waste water injection. The purpose of this project is to attempt to utilize detailed knowledge of the stress field to identify which pre-existing faults could be potentially active in response to injection-related pore pressure increases. Over 50 new stress orientations have been obtained, principally utilizing wellbore image data provided by the oil and gas industry. These data reveal a very uniform ENE direction of maximum compressive stress through much of the state. As earthquake focal plane mechanisms indicate strike-slip faulting, the stress orientation data indicate which pre-existing faults are potentially active. The data are consistent with slip on the near-vertical, NE-trending fault associated with at least one of the M 5+ earthquakes in the Prague, OK sequence in 2011. If successful, it would demonstrate that combining detailed information about pre-existing faults and the current stress field could be used to guide the siting of injection wells so as to decrease the potential for injection-related seismicity.

  2. Tectonic geomorphology and neotectonics of the Kyaukkyan Fault, Myanmar

    NASA Astrophysics Data System (ADS)

    Crosetto, Silvia; Watkinson, Ian; Gori, Stefano; Falcucci, Emanuela; Min, Soe

    2016-04-01

    The Kyaukkyan Fault is a dextral strike-slip fault, part of a complex zone of active dextral transpression that absorbs most of the northward motion of India relative to Sundaland. While much of the strike-slip displacement is localised in western Myanmar and along the prominent Sagaing Fault, significant dextral shear also occurs across the Kyaukkyan Fault, on the Shan Plateau in the east. The largest recorded earthquake in Myanmar occurred on the Kyaukkyan Fault in 1912, near Maymyo (Mw 7.7), but the fault has generated little significant seismicity since then. Despite its demonstrated seismic potential and remarkable topographic expression, the fault's neotectonic history remains poorly known. Interpretation of ≤30 m Landsat TM/ETM+ images, together with field investigations, reveals deformation features developed along the Kyaukkyan Fault system, mostly indicative of Quaternary dextral strike-slip faulting. Well-marked fault scarps and valleys locate the fault especially in its northernmost and southernmost part; geomorphic features related with Kyaukkyan Fault activity are sag ponds, shutter ridges, offset and beheaded streams, triangular facets and low-sinuosity mountain fronts. Geomorphic markers of young fault activity such as offset and deformed alluvial fans, wind-gaps were also identified during field observation. The fault's central section is characterised by a complex pull-apart system, whose normal border faults show signals of relatively slow neotectonic activity. In the central part of the basin, deformation of Quaternary sediments by a locally-buried cross-basin fault system includes dip-slip faulting, where subsidence adjacent to linear ridges is suggested by notably active mountain fronts, dextral strike-slip faulting and local transpression. Although no direct evidence of a 1912 surface rupture has been detected, the fresh geomorphic expression of the cross-basin fault system indicates that it is likely to have been the focus of that event

  3. Impact of active faulting on the post LGM infill of Le Bourget Lake (western Alps, France)

    NASA Astrophysics Data System (ADS)

    de La Taille, Camille; Jouanne, François; Crouzet, Christian; Beck, Christian; Jomard, Hervé; de Rycker, Koen; Van Daele, Maarten

    2015-11-01

    We have used high resolution seismic imaging to detect and characterize the recent deformation recorded by the Quaternary sediments of Le Bourget Lake. The last glacial episodes (MIS 6a and 2, i.e., Riss and Würm) scoured out an elongated over-deepened basin to more than 300 m below the present lake level and the basin accumulated 150 m of post-LGM to Holocene sediments. The well-stratified character of the infill is locally disturbed by tectonic deformations and gravity reworking. A northern fault zone, in continuation with the left-lateral strike-slip Culoz Fault, is imaged within the Holocene and Late Glacial accumulations. A southern fault zone is also detected, which can be related to the sub-lacustrine continuation of a much smaller fault affecting the Jura alpine foreland: the Col du Chat left lateral strike-slip fault. Different generations of fractures have been identified in the lake, allowing correlation and mapping. In pre-Quaternary substratum, the Culoz Fault has a N 160° orientation. Within the post-LGM sediments, fractures related to the Culoz Fault have an orientation between N135° and 95°. A Cloos model (1932) is thus proposed to explain the observed pattern of lacustrine deformations. The calculated horizontal slip rate for Culoz Fault during Holocene is about 1.3 mm·yr- 1, and for the Col du Chat Fault is around 0.6 mm·yr- 1.

  4. Integrated near surface geophysics across the active Mount Marzano Fault System (southern Italy): seismogenic hints

    NASA Astrophysics Data System (ADS)

    Galli, P. A. C.; Giocoli, A.; Peronace, E.; Piscitelli, S.; Quadrio, B.; Bellanova, J.

    2014-01-01

    Here, we describe an original geophysical multi-method approach applied to the Mount Marzano Fault System. This is one of the most hazardous seismogenic faults of the Apennines (Irpinia, southern Italy), and it was responsible for the 1980, Mw 6.9, earthquake, along with many others before. We carried out electrical resistivity tomography (ERT), ground penetrating radar (GPR) measurements, and horizontal-to-vertical spectral ratio (HVSR) microtremor analysis along several common transects designed across the potential and/or certain fault traces. The data obtained from these non-invasive, inexpensive, expeditious methods mutually integrate with and complement each other, providing a valuable subsurface image of the near surface fault architecture. ERT depicts the general shallow image of the fault zone and of the fault-controlled sedimentary basin, with the depth of the buried bedrock cross-correlated through ambient-noise HVSR results. GPR delineates the very shallow geometry of the fault and of the associated deformation. Coupled with previous paleoseismological studies, these data allow the evaluation of some fault parameters and the precise locating of the fault trace, to aid future paleoseismological investigations aimed at seismic risk reduction programs.

  5. Fault tectonics and earthquake hazards in parts of southern California. [penninsular ranges, Garlock fault, Salton Trough area, and western Mojave Desert

    NASA Technical Reports Server (NTRS)

    Merifield, P. M. (Principal Investigator); Lamar, D. L.; Gazley, C., Jr.; Lamar, J. V.; Stratton, R. H.

    1976-01-01

    The author has identified the following significant results. Four previously unknown faults were discovered in basement terrane of the Peninsular Ranges. These have been named the San Ysidro Creek fault, Thing Valley fault, Canyon City fault, and Warren Canyon fault. In addition fault gouge and breccia were recognized along the San Diego River fault. Study of features on Skylab imagery and review of geologic and seismic data suggest that the risk of a damaging earthquake is greater along the northwestern portion of the Elsinore fault than along the southeastern portion. Physiographic indicators of active faulting along the Garlock fault identifiable in Skylab imagery include scarps, linear ridges, shutter ridges, faceted ridges, linear valleys, undrained depressions and offset drainage. The following previously unrecognized fault segments are postulated for the Salton Trough Area: (1) An extension of a previously known fault in the San Andreas fault set located southeast of the Salton Sea; (2) An extension of the active San Jacinto fault zone along a tonal change in cultivated fields across Mexicali Valley ( the tonal change may represent different soil conditions along opposite sides of a fault). For the Skylab and LANDSAT images studied, pseudocolor transformations offer no advantages over the original images in the recognition of faults in Skylab and LANDSAT images. Alluvial deposits of different ages, a marble unit and iron oxide gossans of the Mojave Mining District are more readily differentiated on images prepared from ratios of individual bands of the S-192 multispectral scanner data. The San Andreas fault was also made more distinct in the 8/2 and 9/2 band ratios by enhancement of vegetation differences on opposite sides of the fault. Preliminary analysis indicates a significant earth resources potential for the discrimination of soil and rock types, including mineral alteration zones. This application should be actively pursued.

  6. 7 CFR 981.441 - Credit for market promotion activities, including paid advertising.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Credit for market promotion activities, including paid... promotion activities, including paid advertising. (a) In order for a handler to receive credit for his/her...) Other market promotion activities. Credit-Back shall be granted for market promotion other than...

  7. Glacier ice mass fluctuations and fault instability in tectonically active Southern Alaska

    USGS Publications Warehouse

    Sauber, J.M.; Molnia, B.F.

    2004-01-01

    Across the plate boundary zone in south central Alaska, tectonic strain rates are high in a region that includes large glaciers undergoing wastage (glacier retreat and thinning) and surges. For the coastal region between the Bering and Malaspina Glaciers, the average ice mass thickness changes between 1995 and 2000 range from 1 to 5 m/year. These ice changes caused solid Earth displacements in our study region with predicted values of -10 to 50 mm in the vertical and predicted horizontal displacements of 0-10 mm at variable orientations. Relative to stable North America, observed horizontal rates of tectonic deformation range from 10 to 40 mm/year to the north-northwest and the predicted tectonic uplift rates range from approximately 0 mm/year near the Gulf of Alaska coast to 12 mm/year further inland. The ice mass changes between 1995 and 2000 resulted in discernible changes in the Global Positioning System (GPS) measured station positions of one site (ISLE) located adjacent to the Bagley Ice Valley and at one site, DON, located south of the Bering Glacier terminus. In addition to modifying the surface displacements rates, we evaluated the influence ice changes during the Bering glacier surge cycle had on the background seismic rate. We found an increase in the number of earthquakes (ML???2.5) and seismic rate associated with ice thinning and a decrease in the number of earthquakes and seismic rate associated with ice thickening. These results support the hypothesis that ice mass changes can modulate the background seismic rate. During the last century, wastage of the coastal glaciers in the Icy Bay and Malaspina region indicates thinning of hundreds of meters and in areas of major retreat, maximum losses of ice thickness approaching 1 km. Between the 1899 Yakataga and Yakutat earthquakes (Mw=8.1, 8.1) and prior to the 1979 St. Elias earthquake (M s=7.2), the plate interface below Icy Bay was locked and tectonic strain accumulated. We used estimated ice mass

  8. Hanging canyons of Haida Gwaii, British Columbia, Canada: Fault-control on submarine canyon geomorphology along active continental margins

    NASA Astrophysics Data System (ADS)

    Harris, Peter T.; Barrie, J. Vaughn; Conway, Kim W.; Greene, H. Gary

    2014-06-01

    Faulting commonly influences the geomorphology of submarine canyons that occur on active continental margins. Here, we examine the geomorphology of canyons located on the continental margin off Haida Gwaii, British Columbia, that are truncated on the mid-slope (1200-1400 m water depth) by the Queen Charlotte Fault Zone (QCFZ). The QCFZ is an oblique strike-slip fault zone that has rates of lateral motion of around 50-60 mm/yr and a small convergent component equal to about 3 mm/yr. Slow subduction along the Cascadia Subduction Zone has accreted a prism of marine sediment against the lower slope (1500-3500 m water depth), forming the Queen Charlotte Terrace, which blocks the mouths of submarine canyons formed on the upper slope (200-1400 m water depth). Consequently, canyons along this margin are short (4-8 km in length), closely spaced (around 800 m), and terminate uniformly along the 1400 m isobath, coinciding with the primary fault trend of the QCFZ. Vertical displacement along the fault has resulted in hanging canyons occurring locally. The Haida Gwaii canyons are compared and contrasted with the Sur Canyon system, located to the south of Monterey Bay, California, on a transform margin, which is not blocked by any accretionary prism, and where canyons thus extend to 4000 m depth, across the full breadth of the slope.

  9. Multi-phase inversion tectonics related to the Hendijan-Nowrooz-Khafji Fault activity, Zagros Mountains, SW Iran

    NASA Astrophysics Data System (ADS)

    Kazem Shiroodi, Sadjad; Ghafoori, Mohammad; Faghih, Ali; Ghanadian, Mostafa; Lashkaripour, Gholamreza; Hafezi Moghadas, Naser

    2015-11-01

    Distinctive characteristics of inverted structures make them important criteria for the identification of certain structural styles of folded belts. The interpretation of 3D seismic reflection and well data sheds new light on the structural evolution and age of inverted structures associated to the Hendijan-Nowrooz-Khafji Fault within the Persian Gulf Basin and northeastern margin of Afro-Arabian plate. Analysis of thickness variations of growth strata using "T-Z plot" (thickness versus throw plot) method revealed the kinematics of the fault. Obtained results show that the fault has experienced a multi-phase evolutionary history over six different extension and compression deformation events (i.e. positive and negative inversion) between 252.2 and 11.62 Ma. This cyclic activity of the growth fault was resulted from alteration of sedimentary processes during continuous fault slip. The structural development of the study area both during positive and negative inversion geometry styles was ultimately controlled by the relative motion between the Afro-Arabian and Central-Iranian plates.

  10. Mechanical basis for slip along low-angle normal faults

    NASA Astrophysics Data System (ADS)

    Lecomte, Emmanuel; Le Pourhiet, Laetitia; Lacombe, Olivier

    2012-02-01

    The existence of active low-angle normal faults is much debated because (1) the classical theory of fault mechanics implies that normal faults are locked when the dip is less than 30° and (2) shallow-dipping extensional fault planes do not produce large earthquakes (M > 5.5). However, a number of field observations suggest that brittle deformation occurs on low-angle normal faults at very shallow dip. To reconcile observations and theory, we use an alternative model of fault reactivation including a thick elasto-plastic frictional fault gouge, and test it at large strain by the mean of 2D mechanical modeling. We show that plastic compaction allows reducing the effective friction of faults sufficiently for low-angle normal faults to be active at dip of 20°. As the model predicts that these faults must be active in a slip-hardening regime, it prevents the occurrence of large earthquakes. However, we also evidence the neoformation of Riedel-type shear bands within thick fault zone, which, we believe, may be responsible for repeated small earthquakes and we apply the model to the Gulf of Corinth (Greece).

  11. A test of the longevity of impact-induced faults as preferred sites for later tectonic activity

    NASA Technical Reports Server (NTRS)

    Solomon, Sean C.; Duxbury, Elizabeth D.

    1987-01-01

    The hypothesis that impact-induced faults have been preferred sites for later deformation in response to lithospheric stresses has been suggested for several planets and satellites. This hypothesis is investigated on earth by examining whether terrestrial impact structures show higher rates of nearby earthquake activity than do surrounding intraplate regions. For 28 of 30 probable impact structures having an original crater 20 km or more in diameter, the rates of nearby seismicity have been no higher than the regional background rates. For two large probable impact structures, Vredefort and Charlevoix, with higher than normal rates of nearby seismicity, factors other than slip on impact-induced faults appear to control the occurrence of earthquakes. It is concluded that impact-induced faults, at least on earth, do not persist as lithospheric 'weak zones' for periods in excess of several million years after the impact event.

  12. Influence of a voltage compensation type active superconducting fault current limiter on the transient stability of power system

    NASA Astrophysics Data System (ADS)

    Chen, L.; Tang, Y. J.; Shi, J.; Chen, N.; Song, M.; Cheng, S. J.; Hu, Y.; Chen, X. S.

    2009-10-01

    We have proposed a voltage compensation type active superconducting fault current limiter (SFCL). In this paper, the influence of the SFCL on the transient stability of power system is investigated. For the typical one-machine infinite-bus system, the power-angle characteristics of generator with SFCL are studied in different working conditions, and the transient physical process is analyzed. Using MATLAB SIMULINK, the power-angle swing curves are simulated under different current-limiting modes, fault types and fault clearance times. The results show that the proposed SFCL can effectively reduce the transient swing amplitude of rotor and extend the critical clearance time under mode 1, compared with mode 2 and mode 3 having few effects on enhancing the transient stability.

  13. Precursory signals around epicenters and local active faults prior to inland or coastal earthquakes

    NASA Astrophysics Data System (ADS)

    Valizadeh Alvan, Habibeh

    Although earthquakes are still considered as unpredictable phenomenon but scientific efforts during the past decade have revealed some pronounced changes in the quality and quantity of some materials and natural phenomenon on and above the earth’s surface taking place before strong shakes. Pre-earthquake physical and chemical interactions in the earth’s ground may cause anomalies in temperature, surface latent heat flux (SLHF), relative humidity, upwelling index and chlorophyll-a (Chl-a) concentration on the ground or sea surface. Earthquakes are triggered when the energy accumulated in rocks releases causing ruptures in place of faults. The main purpose of this study is to explore and demonstrate possibility of any changes in surface temperature or latent heat flux before, during and after earthquakes. We expect that variations in these factors are accompanied with the increase of Chl-a concentration on the sea surface and upwelling events prior to coastal earthquake events. For monitoring the changes in surface temperature we used NOAA-AVHRR and microwave radiometers like AMSR-E/Aqua data. SLHF data and upwelling indices are provided by National Centers for Environmental Prediction (NCEP) Reanalysis Project and Pacific Fisheries Environmental Laboratory (PFEL) respectively. Chl-a concentration is also available in MODIS website. Our detailed analyses show significant increase of SLHF and upwelling of nutrient-rich water prior to the main events which is attributed to the raise in surface temperature and Chl-a concentration at that time. Meaningful increases in temperature, relative humidity and SLHF variations from weeks before the earthquakes in epicentral areas and along local active faults are revealed. In addition, considerable anomalies in Chl-a concentration are also attributed to the raise in upwelling index.

  14. The role of mechanical heterogeneities in evaporite sequence during deformation initiated by basement fault activity

    NASA Astrophysics Data System (ADS)

    Adamuszek, Marta; Dabrowski, Marcin; Burliga, Stanisław

    2016-04-01

    Kłodawa Salt Structure (KSS) situated in the centre of the Polish Zechstein Basin started to rise above a basement fault in the Early Triassic. Geological studies of the KSS revealed significant differences in the deformation patterns between the PZ1-PZ2 (intensely deformed) and PZ3-PZ4 (less deformed) cycle evaporites. These two older and two younger cycle evaporite complexes are separated by the thick Main Anhydrite (A3) bed. We use numerical simulations to assess the impact of a thick anhydrite bed on intrasalt deformation. In our models, the overburden consists of clastic sediments. A normal fault located in the rigid basement beneath the salt is activated due to model extension. At the same time, the sedimentation process takes place. The evaporites consist of a salt bed intercalated with a thick anhydrite layer of varying position and geometry. To understand the role of anhydrite layer, we run comparative simulations, in which no anhydrite layer is present. In the study, we use our own numerical codes implemented in MATLAB combined with the MILAMIN and MUTILS numerical packages. Our investigations revealed a significant influence of the anhydrite on deformation style in the evaporate series. The supra-anhydrite domain is characterized by weaker deformation and lower rates of salt flow in comparison to the sub-anhydrite domain. The highest contrast in the rate of salt flow between the two domains is observed in the case of the anhydrite layer situated close to the bottom of the salt complex. The thick anhydrite layer additionally diminishes the deformation rate in the supra-anhydrite domain and can lead to detachment of the basement deformation from its overlay. Our numerical simulations showed that the presence of the A3 Main Anhydrite bed could be the dominant factor responsible for the decoupling of deformation in the KSS salt complex.

  15. Subsurface geometry and evolution of the Seattle fault zone and the Seattle Basin, Washington

    USGS Publications Warehouse

    ten Brink, U.S.; Molzer, P.C.; Fisher, M.A.; Blakely, R.J.; Bucknam, R.C.; Parsons, T.; Crosson, R.S.; Creager, K.C.

    2002-01-01

    The Seattle fault, a large, seismically active, east-west-striking fault zone under Seattle, is the best-studied fault within the tectonically active Puget Lowland in western Washington, yet its subsurface geometry and evolution are not well constrained. We combine several analysis and modeling approaches to study the fault geometry and evolution, including depth-converted, deep-seismic-reflection images, P-wave-velocity field, gravity data, elastic modeling of shoreline uplift from a late Holocene earthquake, and kinematic fault restoration. We propose that the Seattle thrust or reverse fault is accompanied by a shallow, antithetic reverse fault that emerges south of the main fault. The wedge enclosed by the two faults is subject to an enhanced uplift, as indicated by the boxcar shape of the shoreline uplift from the last major earthquake on the fault zone. The Seattle Basin is interpreted as a flexural basin at the footwall of the Seattle fault zone. Basin stratigraphy and the regional tectonic history lead us to suggest that the Seattle fault zone initiated as a reverse fault during the middle Miocene, concurrently with changes in the regional stress field, to absorb some of the north-south shortening of the Cascadia forearc. Kingston Arch, 30 km north of the Seattle fault zone, is interpreted as a more recent disruption arising within the basin, probably due to the development of a blind reverse fault.

  16. OpenStudio - Fault Modeling

    SciTech Connect

    Frank, Stephen; Robertson, Joseph; Cheung, Howard; Horsey, Henry

    2014-09-19

    This software record documents the OpenStudio fault model development portion of the Fault Detection and Diagnostics LDRD project.The software provides a suite of OpenStudio measures (scripts) for modeling typical HVAC system faults in commercial buildings and also included supporting materials: example projects and OpenStudio measures for reporting fault costs and energy impacts.

  17. Glacier Ice Mass Fluctuations and Fault Instability in Tectonically Active Southern Alaska

    NASA Technical Reports Server (NTRS)

    SauberRosenberg, Jeanne M.; Molnia, Bruce F.

    2003-01-01

    Across southern Alaska the northwest directed subduction of the Pacific plate is accompanied by accretion of the Yakutat terrane to continental Alaska. This has led to high tectonic strain rates and dramatic topographic relief of more than 5000 meters within 15 km of the Gulf of Alaska coast. The glaciers of this area are extensive and include large glaciers undergoing wastage (glacier retreat and thinning) and surges. The large glacier ice mass changes perturb the tectonic rate of deformation at a variety of temporal and spatial scales. We estimated surface displacements and stresses associated with ice mass fluctuations and tectonic loading by examining GPS geodetic observations and numerical model predictions. Although the glacial fluctuations perturb the tectonic stress field, especially at shallow depths, the largest contribution to ongoing crustal deformation is horizontal tectonic strain due to plate convergence. Tectonic forces are thus the primary force responsible for major earthquakes. However, for geodetic sites located < 10-20 km from major ice mass fluctuations, the changes of the solid Earth due to ice loading and unloading are an important aspect of interpreting geodetic results. The ice changes associated with Bering Glacier s most recent surge cycle are large enough to cause discernible surface displacements. Additionally, ice mass fluctuations associated with the surge cycle can modify the short-term seismicity rates in a local region. For the thrust faulting environment of the study region a large decrease in ice load may cause an increase in seismic rate in a region close to failure whereas ice loading may inhibit thrust faulting.

  18. On the mechanical behaviour of a low-angle normal fault: the Alto Tiberina fault (Northern Apennines, Italy) system case study

    NASA Astrophysics Data System (ADS)

    Vadacca, Luigi; Casarotti, Emanuele; Chiaraluce, Lauro; Cocco, Massimo

    2016-11-01

    Geological and seismological observations have been used to parameterize 2-D numerical elastic models to simulate the interseismic deformation of a complex extensional fault system located in the Northern Apennines (Italy). The geological system is dominated by the presence of the Alto Tiberina fault (ATF), a large (60 km along strike) low-angle normal fault dipping 20° in the brittle crust (0-15 km). The ATF is currently characterized by a high and constant rate of microseismic activity, and no moderate-to-large magnitude earthquakes have been associated with this fault in the past 1000 years. Modelling results have been compared with GPS data in order to understand the mechanical behaviour of this fault and a suite of minor syn- and antithetic normal fault segments located in the main fault hanging wall. The results of the simulations demonstrate the active role played by the Alto Tiberina fault in accommodating the ongoing tectonic extension in this sector of the chain. The GPS velocity profile constructed through the fault system cannot be explained without including the ATF's contribution to deformation, indicating that this fault, although misoriented, has to be considered tectonically active and with a creeping behaviour below 5 km depth. The low-angle normal fault also shows a high degree of tectonic coupling with its main antithetic fault (the Gubbio fault), suggesting that creeping along the ATF may control the observed strain localization and the pattern of microseismic activity.

  19. Geomechanical Risk Assessment on Shear Activation of Faults in the CO2 Storage Test Site, Offshore Pohang, South Korea

    NASA Astrophysics Data System (ADS)

    Jo, Y.; Chang, C.; Shinn, Y. J.; Song, I.; Kwon, Y. K.

    2015-12-01

    A pilot CO2 sequestration test project is underway in offshore Pohang, South Korea. The target brine aquifer for CO2 storage is 100 m-thick sandstone/conglomerate formations at a depth range between 750 and 850 mbsf (meter below seafloor), which were verified by a 3D seismic survey and a cored borehole (980 m deep). We also found that a family of steep-dip, NE-striking faults cross the target aquifer. In order to analyze potential risk of shear activation along the faults, we characterize in situ stress state at the site. Borehole image logs, generated by an acoustic televiewer tool showed borehole breakouts along the whole logged section to ~705 mbsf, which consistently indicate an average maximum horizontal principal stress (SHmax) direction of N135°±15°E. A leak-off test conducted at the bottom of a casing shoe (700 mbsf) yielded the magnitude of the minimum horizontal principal stress (Shmin) of 12.1 MPa, which is lower than the vertical stress (Sv =14.8 MPa). For the given Shmin and Sv conditions, we used the logged breakout widths and laboratory determined rock compressive strength to constrain possible SHmax magnitudes that could create the observed breakouts. Our stress estimation indicates that the stress regime in the CO2 injection test site is in favor of strike-slip faulting (Shmin < Sv < SHmax). We utilized our estimated stress conditions to analyze slip tendency of the faults. All regional-scale faults turn out to have relatively low slip tendency under the given stress condition, suggesting a low risk of triggering shear activation of faults during CO2 injection.

  20. Spatial and temporal variation of palaeoseismic activity at an intraplate, historically quiescent structure: The Concud fault (Iberian Chain, Spain)

    NASA Astrophysics Data System (ADS)

    Lafuente, Paloma; Arlegui, Luis E.; Liesa, Carlos L.; Pueyo, Óscar; Simón, José L.

    2014-09-01

    Several faults in the Teruel and Jiloca grabens (Iberian Chain, NE Spain), particularly the targeted Concud fault, show evidences of recent, continuous activity, despite their scarce instrumental and historic seismic record. Three trenches are studied in two locations (central and southeastern sectors of the Concud fault, respectively). After comparing with previous works, we reconstruct a palaeoseismic succession with nine events distributed along a maximum time lapse bracketed between 81.6 and 14.0 ka. This succession involves an average recurrence interval of 7.4 ± 2.8 ka, with individual interseismic periods between 4 and 11 ka. The calculated coseismic displacements range from 0.6 to 2.7 m, with an average value of 1.9 m that results in a slip rate of 0.26 mm/a. Due to the incomplete sedimentary record for Holocene times, we cannot affirm that the youngest event detected was actually the last one. We conjecture that some other events may have occurred during the period between 15.0 and 3.4 ka. Temporal and spatial variations have been detected in palaeoseismic activity, specifically in the distribution of coseismic displacements. First, a non-steady slip rate is evidenced during Plio-Pleistocene times: a long-term tendency towards increasing slip rate is modulated in detail by the occurrence of minor cycles, as the sequence of increasing/decreasing activity recorded within the studied time window suggests. Secondly, an asymmetric distribution of coseismic slip along the fault trace is observed, paralleling the distribution of total fault throw, which shows an absolute maximum close to the southeastern tip. A combination of factors is proposed to explain this: branching of the main fault; dominant, remote-stress-driven slip towards N 220° E on the NW-SE fault segment; guided movement on the passive, NNW-SSE segment giving rise to an oblique roll-over monocline; and decoupling of the hanging-wall block owing to the transverse Los Mansuetos-Valdecebro fault

  1. Structural analysis of the Wallula Gap fault, southeastern Washington

    SciTech Connect

    McQuarrie, N. . Dept. of Geology)

    1993-04-01

    The Olympic-Wallowa lineament in the area between Wallula Gap, Washington and Milton-Freewater, Oregon is a 200-m-high escarpment, the position of which is controlled by a zone of northwest-striking faults termed the Wallula Fault Zone (WFZ). Historical seismicity, including the 1936 magnitude 5--6 Milton-Freewater earthquake, indicates that some faults of the WFZ may be active. Recent studies (Mann, 1993) have revealed evidence for Quaternary motion on the Umapine Fault, the southern boundary fault of the WFZ. Abrupt topographic relief, faceted spurs, and offset drainages also imply Quaternary motion along the northern boundary fault, the Wallula Gap Fault. A detailed study of exposures of the Wallula Gap Fault in stream gullies revealed a narrow zone of northwest-striking synthetic faults dipping steeply to the northeast. Horizontal slickenline on many of the bedrock surfaces indicate that the last motion was strike-slip, although drag folds and vertical displacement of basalt flows imply past normal motion. Although fault planes have yet to be observed cutting Quaternary sediments, clastic dikes of Pleistocene Missoula Flood slackwater sediments (Touchet beds) are found in both basalt bedrock and fault breccia. The location of these dikes near the fault and their similar orientations implies a genetic relationship. Vertical stratification of the dikes into alternating coarse- and fine-grained laminations indicates multiple injections.

  2. Detection of active faults using EMR-Technique and Cerescope at Landau area in central Upper Rhine Graben, SW Germany

    NASA Astrophysics Data System (ADS)

    Hagag, Wael; Obermeyer, Hennes

    2016-01-01

    Two conjugate sets of active faults oriented NNE-SSW and NNW-SSE have been detected at Landau area in SW Germany. These faults follow the old trends of the rift-related structures predominating in the Upper Rhine Graben (URG), which originated during Late Eocene-Miocene time. Linear and horizontal measurements were performed by using the Cerescope device and interpreted, applying the Electromagnetic Radiation (EMR) Technique. Linear EMR-profiles were helpful for mapping active faults, while the main horizontal stress (σH, N to NNE) was easily identified with EMR-horizontal measurements. Reactivation of rift-related structures of the Upper Rhine Graben at Landau area produces a new system of active shallow fractures following old trends, and has been detected through the present study by Cerescope applying the EMR-Technique. The present results imply that the Enhanced Geothermal System (EGS) to the south of Landau has a great impact on reactivation of the pre-existing rift-related faults by mechanical hydro-fracturing occurring within the reservoir rocks underneath the area.

  3. Using focal mechanism solutions to correlate earthquakes with faults in the Lake Tahoe-Truckee area, California and Nevada, and to help design LiDAR surveys for active-fault reconnaissance

    NASA Astrophysics Data System (ADS)

    Cronin, V. S.; Lindsay, R. D.

    2011-12-01

    Geomorphic analysis of hillshade images produced from aerial LiDAR data has been successful in identifying youthful fault traces. For example, the recently discovered Polaris fault just northwest of Lake Tahoe, California/Nevada, was recognized using LiDAR data that had been acquired by local government to assist land-use planning. Subsequent trenching by consultants under contract to the US Army Corps of Engineers has demonstrated Holocene displacement. The Polaris fault is inferred to be capable of generating a magnitude 6.4-6.9 earthquake, based on its apparent length and offset characteristics (Hunter and others, 2011, BSSA 101[3], 1162-1181). Dingler and others (2009, GSA Bull 121[7/8], 1089-1107) describe paleoseismic or geomorphic evidence for late Neogene displacement along other faults in the area, including the West Tahoe-Dollar Point, Stateline-North Tahoe, and Incline Village faults. We have used the seismo-lineament analysis method (SLAM; Cronin and others, 2008, Env Eng Geol 14[3], 199-219) to establish a tentative spatial correlation between each of the previously mentioned faults, as well as with segments of the Dog Valley fault system, and one or more earthquake(s). The ~18 earthquakes we have tentatively correlated with faults in the Tahoe-Truckee area occurred between 1966 and 2008, with magnitudes between 3 and ~6. Given the focal mechanism solution for a well-located shallow-focus earthquake, the nodal planes can be projected to Earth's surface as represented by a DEM, plus-or-minus the vertical and horizontal uncertainty in the focal location, to yield two seismo-lineament swaths. The trace of the fault that generated the earthquake is likely to be found within one of the two swaths [1] if the fault surface is emergent, and [2] if the fault surface is approximately planar in the vicinity of the focus. Seismo-lineaments from several of the earthquakes studied overlap in a manner that suggests they are associated with the same fault. The surface

  4. Simulation of broadband ground motion including nonlinear soil effects for a magnitude 6.5 earthquake on the Seattle fault, Seattle, Washington

    USGS Publications Warehouse

    Hartzell, S.; Leeds, A.; Frankel, A.; Williams, R.A.; Odum, J.; Stephenson, W.; Silva, W.

    2002-01-01

    The Seattle fault poses a significant seismic hazard to the city of Seattle, Washington. A hybrid, low-frequency, high-frequency method is used to calculate broadband (0-20 Hz) ground-motion time histories for a M 6.5 earthquake on the Seattle fault. Low frequencies (1 Hz) are calculated by a stochastic method that uses a fractal subevent size distribution to give an ω-2 displacement spectrum. Time histories are calculated for a grid of stations and then corrected for the local site response using a classification scheme based on the surficial geology. Average shear-wave velocity profiles are developed for six surficial geologic units: artificial fill, modified land, Esperance sand, Lawton clay, till, and Tertiary sandstone. These profiles together with other soil parameters are used to compare linear, equivalent-linear, and nonlinear predictions of ground motion in the frequency band 0-15 Hz. Linear site-response corrections are found to yield unreasonably large ground motions. Equivalent-linear and nonlinear calculations give peak values similar to the 1994 Northridge, California, earthquake and those predicted by regression relationships. Ground-motion variance is estimated for (1) randomization of the velocity profiles, (2) variation in source parameters, and (3) choice of nonlinear model. Within the limits of the models tested, the results are found to be most sensitive to the nonlinear model and soil parameters, notably the over consolidation ratio.

  5. Time constraints on faults activity in the Eastern California Shear Zone from U-Pb (SHRIMP-RG) dating of syntectonic opal

    NASA Astrophysics Data System (ADS)

    Nuriel, P.; Maher, K.; Miller, D. M.

    2013-12-01

    Absolute time constraints for fault activity are of fundamental importance in active fault systems. Such constraints are necessary for estimation of long-term slip-rates and earthquake recurrence intervals required for seismic-hazard assessments. Notwithstanding, paleoseismological records are often limited to the past 1 Ma, and important information such as fault initiation and early stage displacement are seldom determined. Here we present a novel methodological approach for direct dating of brittle deformation events over a geological time scale. We use in situ U-Pb SHRIMP-RG (Sensitive High Resolution Ion Microprobe - Reverse Geometry) analyses of opal precipitates in order to constrain the relative and absolute timing of brittle deformation events. The Mojave Desert fault segments within the Eastern California Shear Zone (ECSZ) are ideal faults to investigate the long-term history because of the need for improved constraints on the timing of fault initiation and the observed discrepancy between long-term and short-term estimates for strain accumulation rates in this area. We analyzed fault-related opal samples from ten different fault exposures within the Camp Rock, Cave Mountain, and the Cady fault systems. Millimeter size fragments of fault-related opal, occurring as fault coating, filling or fault-breccia cement, were imaged using cathodoluminescence and backscattering electron microscopy in order to identify distinct phases of opal associated with specific syntectonic microstructures. Sub-samples within each phase are then targeted with multiple SHRIMP-RG analyses (<50 μm in diameter) to allow the construction of 238U/208Pb-206Pb/208Pb and/or Tera-Wasserburg U-Pb isochrons. Of the 50 distinct phases that were identified, 20 were successfully dated and U-Pb age results range from 8.4 to 0.58 Ma. The timing of fault initiation along the Cave Mountain Fault system was previously estimated to be between 15 Ma and 5 Ma. Our results suggest that initial

  6. A Comparison of Structural Data and Seismic Images For Low-Angle Normal Faults in the Northern Apennines (Central Italy): Constraints on Geometry and Activity

    NASA Astrophysics Data System (ADS)

    Collettini, C.; Barchi, M. R.

    2001-12-01

    During the last 20 Myr extensional tectonics in the Northern Apennines have moved from the Tyrrhenian sea toward east. Much of the extension is due to low-angle east-dipping normal faults now exhumed in the Tyrrhenian islands and Tuscany, while still accommodating deformation in the Apenninic chain (Umbria region 200 km eastward). This tectonic framework provide an example where exhumed structures can be compared with active extensional structures and processes affecting the Umbria region. It is here proposed the case study of two of these low angle normal faults, the Zuccale fault (Zf), cropping out in the Elba island and the Altotiberina fault (ATF) mainly detected by seismic profiles crossing the Umbria region. The Zf in the eastern part of the Elba island juxtaposes along a gently ( ~ 10° ) eastward dipping contact, the Upper Cretaceous Helminthoid flysch in its hangingwall over the Permian-Triassic (?) phyllitic basement in its footwall. Structural analysis of the brittle structures that characterise the fault zone has been used to constraint the state of stress under which the fault slipped. From the N-S trending vertical vein system perpendicular to the slickenlines of the fault plane and from the Andersonian normal faults present within the fault gouge, some of them rotated according to a top to the east movement, we infer that (1) the maximum principal stress was sub vertical during the fault activity (2) the fault accommodate slip under low values of differential stress and at dips similar to its present flat geometry (3) local fluid overpressures were attained during the fault activity favoured by a thick fault gouge. The geological scenario described in the Elba island shows similarities with the active deformation of the Umbria region. Seismic profiles crossing this area matched with surface geology highlight the presence of an east-dipping low-angle ( ~ 20° ) normal fault, the Altotiberina fault (ATF), and antithetic seismogenic structures bounding

  7. Probabilistic seismic hazard at Mt. Etna (Italy): The contribution of local fault activity in mid-term assessment

    NASA Astrophysics Data System (ADS)

    Azzaro, R.; D'Amico, S.; Peruzza, L.; Tuvè, T.

    2013-02-01

    In this work, we tackle the problem of seismic hazard at Etna deriving from the recurrent seismogenic activity of local faults, by adopting two independent methods based on probabilistic approaches. We assess the hazard in terms of macroseismic intensity and represent the occurrence probability calculated for different exposure times both on maps and at fault scale. Seismic hazard maps obtained by applying the "site approach" through the SASHA code and a new probabilistic attenuation model, indicate the eastern flank of the volcano as the most hazardous, with expected intensity (Iexp) in 50 years (i.e. the standard exposure time adopted in the seismic regulations) ranging from degrees IX to X EMS. In shorter exposure periods (20, 10, 5 years), values of Iexp up to IX are also reached in the same area, but they are clearly determined by the earthquakes generated by the Timpe fault system. In order to quantify the contribution of local seismogenic sources to the hazard of the region, we reconstruct the seismic history of each fault and calculate with SASHA the probability that earthquakes of a given intensity may be generated in different exposure times. Results confirm the high level of hazard due to the S. Tecla, Moscarello and Fiandaca faults especially for earthquakes of moderate intensity, i.e. VI ≤ I0 ≤ VII, with probabilities respectively exceeding 50% and 20% in 10 years, and 30% and 10% in 5 years. Occurrence probability of major events (I0 ≥ VIII) at the fault scale has also been investigated by statistics on intertimes. Under stationary assumptions we obtain a probability of 6.8% in 5 years for each structure; by introducing the time-dependency (time elapsed since the last event occurred on each fault) through a BPT model, we identify the Moscarello and S. Tecla faults as the most probable sources to be activated in the next 5 years (2013-2017). This result may represent a useful indication to establish priority criteria for actions aimed at reducing

  8. Software Fault Tolerance: A Tutorial

    NASA Technical Reports Server (NTRS)

    Torres-Pomales, Wilfredo

    2000-01-01

    Because of our present inability to produce error-free software, software fault tolerance is and will continue to be an important consideration in software systems. The root cause of software design errors is the complexity of the systems. Compounding the problems in building correct software is the difficulty in assessing the correctness of software for highly complex systems. After a brief overview of the software development processes, we note how hard-to-detect design faults are likely to be introduced during development and how software faults tend to be state-dependent and activated by particular input sequences. Although component reliability is an important quality measure for system level analysis, software reliability is hard to characterize and the use of post-verification reliability estimates remains a controversial issue. For some applications software safety is more important than reliability, and fault tolerance techniques used in those applications are aimed at preventing catastrophes. Single version software fault tolerance techniques discussed include system structuring and closure, atomic actions, inline fault detection, exception handling, and others. Multiversion techniques are based on the assumption that software built differently should fail differently and thus, if one of the redundant versions fails, it is expected that at least one of the other versions will provide an acceptable output. Recovery blocks, N-version programming, and other multiversion techniques are reviewed.

  9. Late Quaternary Faulting along the San Juan de los Planes Fault Zone, Baja California Sur, Mexico

    NASA Astrophysics Data System (ADS)

    Busch, M. M.; Coyan, J. A.; Arrowsmith, J.; Maloney, S. J.; Gutierrez, G.; Umhoefer, P. J.

    2007-12-01

    As a result of continued distributed deformation in the Gulf Extensional Province along an oblique-divergent plate margin, active normal faulting is well manifest in southeastern Baja California. By characterizing normal-fault related deformation along the San Juan de los Planes fault zone (SJPFZ) southwest of La Paz, Baja California Sur we contribute to understanding the patterns and rates of faulting along the southwest gulf-margin fault system. The geometry, history, and rate of faulting provide constraints on the relative significance of gulf-margin deformation as compared to axial system deformation. The SJPFZ is a major north-trending structure in the southern Baja margin along which we focused our field efforts. These investigations included: a detailed strip map of the active fault zone, including delineation of active scarp traces and geomorphic surfaces on the hanging wall and footwall; fault scarp profiles; analysis of bedrock structures to better understand how the pattern and rate of strain varied during the development of this fault zone; and a gravity survey across the San Juan de los Planes basin to determine basin geometry and fault behavior. The map covers a N-S swath from the Gulf of California in the north to San Antonio in the south, an area ~45km long and ~1-4km wide. Bedrock along the SJPFZ varies from Cretaceous Las Cruces Granite in the north to Cretaceous Buena Mujer Tonalite in the south and is scarred by shear zones and brittle faults. The active scarp-forming fault juxtaposes bedrock in the footwall against Late Quaternary sandstone-conglomerate. This ~20m wide zone is highly fractured bedrock infused with carbonate. The northern ~12km of the SJPFZ, trending 200°, preserves discontinuous scarps 1-2km long and 1-3m high in Quaternary units. The scarps are separated by stretches of bedrock embayed by hundreds of meters-wide tongues of Quaternary sandstone-conglomerate, implying low Quaternary slip rate. Further south, ~2 km north of the

  10. Active faulting within a megacity: the geometry and slip rate of the Pardisan thrust in central Tehran, Iran

    NASA Astrophysics Data System (ADS)

    Talebian, M.; Copley, A. C.; Fattahi, M.; Ghorashi, M.; Jackson, J. A.; Nazari, H.; Sloan, R. A.; Walker, R. T.

    2016-12-01

    Tehran, the capital city of Iran with a population of over 12 million, is one of the largest urban centres within the seismically active Alpine-Himalayan orogenic belt. Although several historic earthquakes have affected Tehran, their relation to individual faults is ambiguous for most. This ambiguity is partly due to a lack of knowledge about the locations, geometries and seismic potential of structures that have been obscured by dramatic urban growth over the past three decades, and which have covered most of the young geomorphic markers and natural exposures. Here we use aerial photographs from 1956, combined with an ˜1 m DEM derived from stereo Pleiades satellite imagery to investigate the geomorphology of a growing anticline above a thrust fault-the Pardisan thrust-within central Tehran. The topography across the ridge is consistent with a steep ramp extending from close to the surface to a depth of ˜2 km, where it presumably connects with a shallow-dipping detachment. No primary fault is visible at the surface, and it is possible that the faulting dissipates in the near surface as distributed shearing. We use optically stimulated luminescence to date remnants of uplifted and warped alluvial deposits that are offset vertically across the Pardisan fault, providing minimum uplift and slip-rates of at least 1 mm yr-1. Our study shows that the faults within the Tehran urban region have relatively rapid rates of slip, are important in the regional tectonics, and have a great impact on earthquake hazard assessment of the city and surrounding region.

  11. Multiscale seismic imaging of active fault zones for hazard assessment: A case study of the Santa Monica fault zone, Los Angeles, California

    USGS Publications Warehouse

    Pratt, T.L.; Dolan, J.F.; Odum, J.K.; Stephenson, W.J.; Williams, R.A.; Templeton, M.E.

    1998-01-01

    High-resolution seismic reflection profiles at two different scales were acquired across the transpressional Santa Monica Fault of north Los Angeles as part of an integrated hazard assessment of the fault. The seismic data confirm the location of the fault and related shallow faulting seen in a trench to deeper structures known from regional studies. The trench shows a series of near-vertical strike-slip faults beneath a topographic scarp inferred to be caused by thrusting on the Santa Monica fault. Analysis of the disruption of soil horizons in the trench indicates multiple earthquakes have occurred on these strike-slip faults within the past 50 000 years, with the latest being 1000 to 3000 years ago. A 3.8-km-long, high-resolution seismic reflection profile shows reflector truncations that constrain the shallow portion of the Santa Monica Fault (upper 300 m) to dip northward between 30?? and 55??, most likely 30?? to 35??, in contrast to the 60?? to 70?? dip interpreted for the deeper portion of the fault. Prominent, nearly continuous reflectors on the profile are interpreted to be the erosional unconformity between the 1.2 Ma and older Pico Formation and the base of alluvial fan deposits. The unconformity lies at depths of 30-60 m north of the fault and 110-130 m south of the fault, with about 100 m of vertical displacement (180 m of dip-slip motion on a 30??-35?? dipping fault) across the fault since deposition of the upper Pico Formation. The continuity of the unconformity on the seismic profile constrains the fault to lie in a relatively narrow (50 m) zone, and to project to the surface beneath Ohio Avenue immediately south of the trench. A very high-resolution seismic profile adjacent to the trench images reflectors in the 15 to 60 m depth range that are arched slightly by folding just north of the fault. A disrupted zone on the profile beneath the south end of the trench is interpreted as being caused by the deeper portions of the trenched strike

  12. An automated continuous system for seismo-geochemical research in an active fault zone in SW Taiwan

    NASA Astrophysics Data System (ADS)

    Yang, T. F.; Hilton, D. R.; Fu, C. C.; Lai, C. W.; Liu, T. K.; Walia, V.; Lai, T. H.

    2014-12-01

    Previous studies have revealed that gas compositions of fluid samples collected from southwestern Taiwan where many hot springs and mud volcanoes are distributed along tectonic sutures show significant variation prior to and after some disaster seismic events [1]. Such variations, including radon activity, CH4/CO2, CO2/3He and 3He/4He ratios of gas compositions, are considered to be precursors of earthquakes in this area. To validate the relationship between fluid compositions and local earthquakes, a continuous monitoring station has been established at Yun-Shuei, which is an artesian well located at an active fault zone in SW Taiwan. It is equipped with a radon detector and a quadrupole mass spectrometer (QMS) for in-situ measurement of the dissolved gas composition. Data is telemetered to Taipei so we are able to monitor variations of gas composition in real time. Furthermore, we also installed a syringe pump apparatus for the retrieval and temporal analysis of helium (SPARTAH) at this station [2]. From the SPARTAH samples, we can obtain detailed time series records of He and anion concentration of the water samples at this station. After continuous measurement for a few months, this automated system has been demonstrated to be feasible for long-term continuous seismo-geochemical research in this area. [1] Yang et al. (2006) PAGEOPH, 163(4), 693-709. [2] Barry et al. (2009) G3, 10(5), DOI: 10.1029/2009GC002422.

  13. Trishear for curved faults

    NASA Astrophysics Data System (ADS)

    Brandenburg, J. P.

    2013-08-01

    Fault-propagation folds form an important trapping element in both onshore and offshore fold-thrust belts, and as such benefit from reliable interpretation. Building an accurate geologic interpretation of such structures requires palinspastic restorations, which are made more challenging by the interplay between folding and faulting. Trishear (Erslev, 1991; Allmendinger, 1998) is a useful tool to unravel this relationship kinematically, but is limited by a restriction to planar fault geometries, or at least planar fault segments. Here, new methods are presented for trishear along continuously curved reverse faults defining a flat-ramp transition. In these methods, rotation of the hanging wall above a curved fault is coupled to translation along a horizontal detachment. Including hanging wall rotation allows for investigation of structures with progressive backlimb rotation. Application of the new algorithms are shown for two fault-propagation fold structures: the Turner Valley Anticline in Southwestern Alberta, and the Alpha Structure in the Niger Delta.

  14. Coseismic Faulting and Folding in an Active Thrust Sheet over Multiple Rupture Cycles Resolved by Integrating Surface and Subsurface Records of Earthquake Deformation

    NASA Astrophysics Data System (ADS)

    Stockmeyer, J. M.; Shaw, J. H.; Brown, N.; Rhodes, E. J.; Wang, M.; Lavin, L. C.; Guan, S.

    2015-12-01

    Many recent thrust fault earthquakes have involved coseismic surface faulting and folding, revealing the complex nature of surface deformation in active thrust sheets. In this study, we characterize deformation along the active Southern Junggar Thrust (SJT) in the Junggar basin, NW China - which sourced the 1906 M8 Manas earthquake - to gain insight into how fault slip at depth is partitioned between faulting and folding strains at Earth's surface by integrating deformed terrace records, subsurface geophysical data, and luminescence geochronology. Using a 1-m digital elevation model and field surveys, we have mapped the precise geometries of fluvial terraces across the entire Tugulu anticline, which lies in the hanging wall of the SJT. These profiles reveal progressive uplift of several terraces along prominent fault scarps where the SJT is surface-emergent. Similarly aged terraces are folded in the backlimb of the Tugulu fold, providing a sequential record of surface folding. These folded terraces are progressively rotated such that the oldest terraces are dipping much steeper than younger terraces within the same fold limb. Using 2- and 3-D seismic reflection data, we integrate subsurface deformation constraints with records of surface strain. Structural interpretations of these seismic data define the geometry of the SJT and reveal that folding is localized across synclinal bends along the SJT. We evaluate a range of distinct fault-related fold models (e.g. fault-bend folding, shear fault-bend folding) to assess which structural style best describes the geometries of the subsurface and surface fold patterns. By doing so, we have the opportunity to directly relate surface fault slip measures from terrace folding and uplift to total fault slip at depth. This integration of surface and subsurface deformation - combined with constraints on terrace ages from post-IR IRSL geochronology - allows us to characterize how fault slip and seismic moment are partitioned

  15. Nuclear actin activates human transcription factor genes including the OCT4 gene.

    PubMed

    Yamazaki, Shota; Yamamoto, Koji; Tokunaga, Makio; Sakata-Sogawa, Kumiko; Harata, Masahiko

    2015-01-01

    RNA microarray analyses revealed that nuclear actin activated many human transcription factor genes including OCT4, which is required for gene reprogramming. Oct4 is known to be activated by nuclear actin in Xenopus oocytes. Our findings imply that this process of OCT4 activation is conserved in vertebrates and among cell types and could be used for gene reprogramming of human cells.

  16. Abnormal fault-recovery characteristics of the fault-tolerant multiprocessor uncovered using a new fault-injection methodology

    NASA Technical Reports Server (NTRS)

    Padilla, Peter A.

    1991-01-01

    An investigation was made in AIRLAB of the fault handling performance of the Fault Tolerant MultiProcessor (FTMP). Fault handling errors detected during fault injection experiments were characterized. In these fault injection experiments, the FTMP disabled a working unit instead of the faulted unit once in every 500 faults, on the average. System design weaknesses allow active faults to exercise a part of the fault management software that handles Byzantine or lying faults. Byzantine faults behave such that the faulted unit points to a working unit as the source of errors. The design's problems involve: (1) the design and interface between the simplex error detection hardware and the error processing software, (2) the functional capabilities of the FTMP system bus, and (3) the communication requirements of a multiprocessor architecture. These weak areas in the FTMP's design increase the probability that, for any hardware fault, a good line replacement unit (LRU) is mistakenly disabled by the fault management software.

  17. Identifying buried segments of active faults in the northern Rio Grande Rift using aeromagnetic, LiDAR,and gravity data, south-central Colorado, USA

    USGS Publications Warehouse

    Ruleman, Cal; Grauch, V. J.

    2013-01-01

    Combined interpretation of aeromagnetic and LiDAR data builds on the strength of the aeromagnetic method to locate normal faults with significant offset under cover and the strength of LiDAR interpretation to identify the age and sense of motion of faults. Each data set helps resolve ambiguities in interpreting the other. In addition, gravity data can be used to infer the sense of motion for totally buried faults inferred solely from aeromagnetic data. Combined interpretation to identify active faults at the northern end of the San Luis Basin of the northern Rio Grande rift has confirmed general aspects of previous geologic mapping but has also provided significant improvements. The interpretation revises and extends mapped fault traces, confirms tectonic versus fluvial origins of steep stream banks, and gains additional information on the nature of active and potentially active partially and totally buried faults. Detailed morphology of surfaces mapped from the LiDAR data helps constrain ages of the faults that displace the deposits. The aeromagnetic data provide additional information about their extents in between discontinuous scarps and suggest that several totally buried, potentially active faults are present on both sides of the valley.

  18. Interacting faults

    NASA Astrophysics Data System (ADS)

    Peacock, D. C. P.; Nixon, C. W.; Rotevatn, A.; Sanderson, D. J.; Zuluaga, L. F.

    2017-04-01

    The way that faults interact with each other controls fault geometries, displacements and strains. Faults rarely occur individually but as sets or networks, with the arrangement of these faults producing a variety of different fault interactions. Fault interactions are characterised in terms of the following: 1) Geometry - the spatial arrangement of the faults. Interacting faults may or may not be geometrically linked (i.e. physically connected), when fault planes share an intersection line. 2) Kinematics - the displacement distributions of the interacting faults and whether the displacement directions are parallel, perpendicular or oblique to the intersection line. Interacting faults may or may not be kinematically linked, where the displacements, stresses and strains of one fault influences those of the other. 3) Displacement and strain in the interaction zone - whether the faults have the same or opposite displacement directions, and if extension or contraction dominates in the acute bisector between the faults. 4) Chronology - the relative ages of the faults. This characterisation scheme is used to suggest a classification for interacting faults. Different types of interaction are illustrated using metre-scale faults from the Mesozoic rocks of Somerset and examples from the literature.

  19. Assessment of active faults for maximum credible earthquakes of the southern California-northern Baja region

    NASA Astrophysics Data System (ADS)

    Slemmons, D. B.; Omalley, P.; Whitney, R. A.; Chung, D. H.; Bernreuter, D. L.

    1982-06-01

    Compilation of a data base is presented for maximum or maximum credible earthquakes that can be used to compute seismic hazard spectra at the San Onofre Nuclear Generating Stations in southern California. Estimates of fault slip rate and estimated recurrence - northern Baja California region are given. According to a direct relationship between the total fault length and the earthquake magnitude, the maximum earthquake for the Offshore Zone of Deformation (OZD) is estimated to be of about 6.8 or 6.9 surface wave magnitude. Another empirical relationship relating the fractional fault length and earthquake magnitude for strike slip faults results in an estimated maximum earthquake of about M/sub S/ = 6.8 for the OZD.

  20. Active tectonic deformation along rejuvenated faults in tropical Borneo: Inferences obtained from tectono-geomorphic evaluation

    NASA Astrophysics Data System (ADS)

    Mathew, Manoj Joseph; Menier, David; Siddiqui, Numair; Kumar, Shashi Gaurav; Authemayou, Christine

    2016-08-01

    active folding of the Rajang Group fold-thrust belt to present and these events reactivated old major faults and minor related dislocations. From geomorphic analysis associated with sedimentary record, we posit that the terrain could have undergone high uplift rates since 5 Ma or multi-phased uplift with periodic intermittent pulses of high and low uplift rates.

  1. Detailed velocity ratio mapping during the aftershock sequence as a tool to monitor the fluid activity within the fault plane

    NASA Astrophysics Data System (ADS)

    Bachura, Martin; Fischer, Tomáš

    2016-11-01

    The rheological properties of Earth materials are expressed by their seismic velocities and VP /VS ratio, which is easily obtained by the Wadati method. Its double-difference version based on cross-correlated waveforms enables focusing on very local structures and allows tracking, monitoring and analysing the fluid activity along faults. We applied the method to three 2014 mainshock-aftershock sequences in the West Bohemia/Vogtland (Czech Republic) earthquake swarm area and found pronounced VP /VS variations in time and space for different clusters of events located on a steeply dipping fault zone at depths ranging from 7 to 11 km. Each cluster reflects the spatial distribution of earthquakes along the fault plane but also the temporal evolution of the activity. Low values of VP /VS ratio down to 1.59 ± 0.02 were identified in the deeper part of the fault zone whereas higher values up to 1.73 ± 0.01 were estimated for clusters located on a shallower segment of the fault. Temporally the low VP /VS values are associated with the early aftershocks, while the higher VP /VS ratios are related only to later aftershocks. We interpret this behaviour as a result of saturation of the focal zone by compressible fluids: in the beginning the mainshock and early aftershocks driven by over-pressured fluids increased the porosity due to opening the fluid pathways. This process was associated with a decrease of the velocity ratio. In later stages the pressure and porosity decreased and the velocity ratio recovered to levels of 1.73, typical for a Poissonian medium and Earth's crust.

  2. LiDAR-Assisted identification of an active fault near Truckee, California

    USGS Publications Warehouse

    Hunter, L.E.; Howle, J.F.; Rose, R.S.; Bawden, G.W.

    2011-01-01

    We use high-resolution (1.5-2.4 points/m2) bare-earth airborne Light Detection and Ranging (LiDAR) imagery to identify, map, constrain, and visualize fault-related geomorphology in densely vegetated terrain surrounding Martis Creek Dam near Truckee, California. Bare-earth LiDAR imagery reveals a previously unrecognized and apparently youthful right-lateral strike-slip fault that exhibits laterally continuous tectonic geomorphic features over a 35-km-long zone. If these interpretations are correct, the fault, herein named the Polaris fault, may represent a significant seismic hazard to the greater Truckee-Lake Tahoe and Reno-Carson City regions. Three-dimensional modeling of an offset late Quaternary terrace riser indicates a minimum tectonic slip rate of 0.4 ?? 0.1 mm/yr.Mapped fault patterns are fairly typical of regional patterns elsewhere in the northern Walker Lane and are in strong coherence with moderate magnitude historical seismicity of the immediate area, as well as the current regional stress regime. Based on a range of surface-rupture lengths and depths to the base of the seismogenic zone, we estimate a maximum earthquake magnitude (M) for the Polaris fault to be between 6.4 and 6.9.

  3. Using core properties and seismic reflectivity to estimate pore pressure in an active decollement fault

    SciTech Connect

    Tobin, H.J.; Moore, J.C.

    1996-12-31

    In the decollement zone of the Barbados accretionary prism, a 3-D seismic image exhibits patchy high-amplitude negative polarity reflections, which have been attributed to large overpressures confined to the fault zone. We collected laboratory P-wave velocity and porosity vs. pore pressure data, using core samples from and adjacent to the decollement zone at ODP Site 948. Logs constrain density and velocity through the decollement zone at Site 948. We use these data to calibrate the reflectivity of the fault zone to pore pressure through waveform and amplitude models of the fault plane reflections. Modeling of the positive polarity Site 948 reflection indicates that it can be explained by a lithologic boundary coincident with the decollement, without anomalous fault properties. By contrast, the dominantly-negative polarity waveform of the reflection {approx}2 km arcward (beneath Site 947) is best modeled by inserting a 16-19 m thick zone of extremely low impedance into the Site 948 impedance structure, with a gradational return to {open_quotes}normal{close_quotes} impedance just above the positive boundary. Relative amplitudes in this reflection indicate a larger impedance contrast than can be accounted for at sub-lithostatic fluid pressure, based on the core properties data. We conclude that lithostatic pore pressure with attendant hydraulic dilation of the fault zone is required to generate the negative-polarity reflections. Mapping of these reflections thus delineates zones of elevated fluid content and zero effective stress in the fault zone.

  4. Using core properties and seismic reflectivity to estimate pore pressure in an active decollement fault

    SciTech Connect

    Tobin, H.J. ); Moore, J.C. )

    1996-01-01

    In the decollement zone of the Barbados accretionary prism, a 3-D seismic image exhibits patchy high-amplitude negative polarity reflections, which have been attributed to large overpressures confined to the fault zone. We collected laboratory P-wave velocity and porosity vs. pore pressure data, using core samples from and adjacent to the decollement zone at ODP Site 948. Logs constrain density and velocity through the decollement zone at Site 948. We use these data to calibrate the reflectivity of the fault zone to pore pressure through waveform and amplitude models of the fault plane reflections. Modeling of the positive polarity Site 948 reflection indicates that it can be explained by a lithologic boundary coincident with the decollement, without anomalous fault properties. By contrast, the dominantly-negative polarity waveform of the reflection [approx]2 km arcward (beneath Site 947) is best modeled by inserting a 16-19 m thick zone of extremely low impedance into the Site 948 impedance structure, with a gradational return to [open quotes]normal[close quotes] impedance just above the positive boundary. Relative amplitudes in this reflection indicate a larger impedance contrast than can be accounted for at sub-lithostatic fluid pressure, based on the core properties data. We conclude that lithostatic pore pressure with attendant hydraulic dilation of the fault zone is required to generate the negative-polarity reflections. Mapping of these reflections thus delineates zones of elevated fluid content and zero effective stress in the fault zone.

  5. Study and comparison of the maximum stress directions and main fault orientations in some active zones in Iran

    NASA Astrophysics Data System (ADS)

    Forouhid, Khatereh; Faraji, Atefeh; Ghorashi, Manouchehr

    2010-05-01

    Study and comparison of the maximum stress directions and main fault orientations in some active zones in Iran Khatereh Forouhid, Manouchehr Ghorashi, Atefeh Faraji Institute of Geophysics, Tehran University, Tehran, Iran kforouhid@yahoo.com Farajiatefeh@yahoo.com The Iranian plateau is the widest active zone in Alpine-Himalayan collision system that is located between two stable platforms, the Arabia in southwest and Eurasia in northeast. The convergence of these two platforms towards each other is the main reason for seismicity and different styles of deformation observed in Iran. In this study, the Iranian plateau is divided into 7 regions based on their seismotectonic characteristics. These regions are; Zagros, Makran, East Iran, Alborz, Kopeh Dagh, Central Iran and Azarbayejan (northwest of Iran). In each region, focal mechanism solutions of early and modern instrumental earthquakes (the only source of information suitable to use for stress distribution study in Iran) with magnitudes more than 5.0 and their relations to active faults are considered. By studying each maximum stress direction based on a group of earthquake focal mechanisms and considering main fault orientations, each region is studied individually. According to these data, some of these regions are divided into smaller parts. These sub-divided parts have some characters that make them different from their neighbors in the same region. In this regard, Zagros is studied in detail based on seismotectonic characteristics and divided into three parts, with N-S maximum stress direction (compressional) in one part and two different kind of NE-SW direction in two other. We use this information to investigate the style and distribution of active faulting in the Zagros and the relationships of this activity with shortening of the Arabia-Eurasia collision. It is worth to mention that as the fault slip will almost occur in the direction of maximum resolved shear stress on the fault plane, probably strain

  6. Late Pleistocene-Holocene Faulting History Along the Northern El Carrizal Fault, Baja California Sur, Mexico: Earthquake Recurrence at a Persistently Active Rifted Margin

    NASA Astrophysics Data System (ADS)

    Maloney, S. J.; Umhoefer, P. J.; Arrowsmith, J. R.; Gutiérrez, G. M.; Santillanez, A. U.; Rittenour, T. R.

    2007-12-01

    The El Carrizal fault is a NW striking, east dipping normal fault located 25 km west of the city of La Paz, Baja California Sur, Mexico and is the westernmost bounding fault of the gulf-margin system at this latitude. The fault is ~70 km long onshore and ~50 km long offshore to the north in La Paz Bay. As many as three Quaternary geomorphic surfaces formed on the footwall and were identified on the basis of mapping and topographic profiling. In the north, the El Carrizal fault splays into multiple strands and exhibits a pattern of alternating N-S and NW-trending segments. Results from geologic mapping, paleoseismic investigations, and preliminary optically stimulated luminescence (OSL) geochronology provide some of the first numerical constraints on late Pleistocene-Holocene faulting along the El Carrizal fault. A 20 m long, 2-3 m deep trench (Trench 28) was excavated across the fault 23 km south of La Paz Bay. The trench was photographed, hand logged, and sampled for OSL dating. The trench revealed a succession of fluvial and channel deposits of sands, gravels, and cobbles. The main fault zone is manifested by a 0.5 m thick wedge-shaped deposit that consists of silty-sand and also contains rotated blocks of caliche- cemented gravels. Preliminary OSL ages from a silty-sand unit offset 2 m by the fault average latest Pleistocene. A trench 4 km south of Trench 28 (Cuadradito Trench) was also documented and sampled for OSL analysis. Preliminary OSL ages from a fluvial sand unit deposited against faulted bedrock range from mid to late Holocene. Sedimentary comparisons and surficial mapping suggest that the Holocene unit at Cuadradito Trench may be correlative to sediment that overlies faulted units from Trench 28. Such a correlation would constrain the timing of the 2 m offset at Trench 28 to be between latest Pleistocene and mid Holocene. A quarry 10 km north of Trench 28 exposes Quaternary sand and gravels buttressed against a 5-10 m wide bedrock shear zone. Here

  7. Active faulting south of the Himalayan Front: Establishing a new plate boundary

    NASA Astrophysics Data System (ADS)

    Yeats, Robert S.; Thakur, V. C.

    2008-06-01

    New tectonic uplifts south of the Salt Range Thrust and Himalayan Front Thrust (HFT) represent an outward step of the plate boundary from the principal tectonic displacement zone into the Indo-Gangetic Plain. In Pakistan, the Lilla Anticline deforms fine-grained overbank deposits of the Jhelum River floodplain 15 km south of the Salt Range. The anticline is overpressured in Eocambrian non-marine strata. In northwest India south of Dehra Dun, the Piedmont Fault (PF) lies 15 km south of the HFT. Coalescing fans derived from the Himalaya form a piedmont (Old Piedmont Zone) 15-20 km wide east of the Yamuna River. This zone is uplifted as much as 15-20 m near the PF, and bedding is tilted 5-7° northeast. Holocene thermoluminescence-optically-stimulated luminescence dates for sediments in the Old Piedmont Zone suggest that the uplift rate might be as high as several mm/a. The Old Piedmont Zone is traced northwest 200 km and southeast another 200 km to the Nepal border. These structures, analogous to protothrusts in subduction zones, indicate that the Himalayan plate boundary is not a single structure but a series of structures across strike, including reactivated parts of the Main Boundary Thrust north of the range front, the HFT sensu stricto, and stepout structures on the Indo-Gangetic Plain. Displacement rates on all these structures must be added to determine the local India-Himalaya convergence rate.

  8. Slip-rate Estimation of Active Fault by Luminescence Dating on Deformed River Terraces at Tsaotun, Central Taiwan

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Chen, W.; Lee, C.

    2003-12-01

    This study carried out luminescence ages of the deformed terraces located at Tsaotun in central Taiwan. These terraces are considered as a result of crustal deformation caused by recent activity of the Chelungpu fault, 1999 surface rupture. Since this active fault runs through urban area, it is urgently needed to figure out its neotectonic behavior, including slip-rate and recurrence interval. Based on new ages, we also discuss the terrace correlation and its related structures. The study terraces are all strath terraces with only a few meters of veneered fluvial deposits on top. Due to the strong stream-power, nearly all the outcrops are dominated by fluvial cobbles, which is worst condition to preserve the syndepositional carbonaceous materials. Alternatively, optical stimulated luminescence (OSL) dating uses sandy quartz as the material and even has longer dating upper limit (up to several hundreds of years). Fortunately, sandy layer are found intercalated within the fluvial cobbles in studying terraces. We adopted the Single-Aliquot Regenerative (SAR) dose protocol on large aliquots of 90-150μ m quartz, which were cleaned using HCL, H2O2 and HF in the usual way. In case of incomplete bleaching during quick deposition, the OSL/TL ratio was adopted to approach the true De. Dosimetry is derived by ICP-MS and XRF analyses. For ascertainment of the initial bleaching of fluvial sediment, the modern samples collected in river bed of Wuhsi were also measured. Based on the results of modern samples, we believe that the residuals are inevitable in younger sediments, especially along the upper stream. On the contrary, the samples older than 10 kyr are little influenced due to the larger age error than the younger ones. The OSL age of the terrace samples in the hanging wall is dated ca. 13 kyr, which has been corrected for poorly-bleaching problem. Comparing to the ages collected down hole in the footwalls, we found out vertical displacements of ca. 67 and 37 m, has been

  9. Technology transfer by means of fault tree synthesis

    NASA Astrophysics Data System (ADS)

    Batzias, Dimitris F.

    2012-12-01

    Since Fault Tree Analysis (FTA) attempts to model and analyze failure processes of engineering, it forms a common technique for good industrial practice. On the contrary, fault tree synthesis (FTS) refers to the methodology of constructing complex trees either from dentritic modules built ad hoc or from fault tress already used and stored in a Knowledge Base. In both cases, technology transfer takes place in a quasi-inductive mode, from partial to holistic knowledge. In this work, an algorithmic procedure, including 9 activity steps and 3 decision nodes is developed for performing effectively this transfer when the fault under investigation occurs within one of the latter stages of an industrial procedure with several stages in series. The main parts of the algorithmic procedure are: (i) the construction of a local fault tree within the corresponding production stage, where the fault has been detected, (ii) the formation of an interface made of input faults that might occur upstream, (iii) the fuzzy (to count for uncertainty) multicriteria ranking of these faults according to their significance, and (iv) the synthesis of an extended fault tree based on the construction of part (i) and on the local fault tree of the first-ranked fault in part (iii). An implementation is presented, referring to 'uneven sealing of Al anodic film', thus proving the functionality of the developed methodology.

  10. Active tectonics, paleoseismology and associated methodological challenges posed by the slow moving Alhama de Murcia fault (SE Iberia)

    NASA Astrophysics Data System (ADS)

    Ferrater, Marta; Ortuño, Maria; Masana, Eulàlia; Pallàs, Raimon; Perea, Hector; Baize, Stephane; García-Meléndez, Eduardo; Martínez-Díaz, José J.; Echeverria, Anna; Rockwell, Thomas; Sharp, Warren D.; Arrowsmith, Ramon; Medialdea, Alicia; Rhodes, Edward

    2016-04-01

    The Alhama de Murcia fault (AMF) is a 87 km-long left-lateral slow moving fault and is responsible for the 5.1 Mw 2011 Lorca earthquake. The characterization of the seismic potential of seismogenic strike-slip slow moving faults is necessary but raises huge methodological challenges, as most paleoseismological and active tectonic techniques have been designed on and for fast moving faults. The AMF is used here as a pilot study area to adapt the traditional geomorphological and trenching analyses, especially concerning the precise quantification of offset channels. We: 1) adapted methodologies to slow moving faults, 2) obtained, for the first time, the slip rate of the AMF, and 3) updated its recurrence period and maximum expected magnitude. Morphotectonic studies aim to use the measured tectonic offset of surface channels to calculate seismic parameters. However, these studies lack a standard criterion to score the analysed features. We improved this by differentiating between subjective and objective qualities, and determining up to three objective parameters (lithological changes, associated morphotectonics and shape, and three shape sub-parameters; all ranging from 0 to 1). By applying this methodology to the AMF, we identified and characterized 138 offset features that we mapped on a high-resolution (0.5 × 0.5 m pixel size) Digital Elevation Model (DEM) from a point cloud acquired in 2013 by airborne light detection and ranging (lidar). The identified offsets, together with the ongoing datings, are going to be used to calculate the lateral slip rate of the AMF. In three-dimensional trenches, we measured the offsets of a buried channel by projecting the far-field tendency of the channel onto the fault. This procedure is inspired by the widespread geomorphological procedure and aims to avoid the diffuse deformation in the fault zone associated with slow moving faults. The calculation of the 3D tendency of the channel and its projection onto the fault permitted

  11. Inspection and rehabilitation of tunnels across faults

    SciTech Connect

    Abramson, L.W.; Schmidt, B.

    1995-12-31

    The inspection and rehabilitation of tunnels that cross faults is unique because they usually are in use and have a large variety of alternative lining types including bare rock, concrete, or steel often coated with accumulations of dirt, grime, algae and other minerals. Inspection methods are important including what to look for, how to clean the inner tunnel lining surfaces, non-destructive testing, coring, soundings, air quality detection and protection, ventilation, lightning, etc. Rehabilitation of tunnels crossing faults requires a practiced knowledge of underground design and construction practices. The most common methods of rehabilitation include grouting and concreting. The Variety of water, wastewater, transit, and highway tunnels in California provide ample examples of tunnels, new and old, that cross active faults. This paper will address specific methods of tunnel inspection and maintenance at fault crossings and give examples of relevant highway, transit, water, and wastewater projects and studies in California to demonstrate the discussions presented.

  12. Modeling fault diagnosis as the activation and use of a frame system. [for pilot problem-solving rating

    NASA Technical Reports Server (NTRS)

    Smith, Philip J.; Giffin, Walter C.; Rockwell, Thomas H.; Thomas, Mark

    1986-01-01

    Twenty pilots with instrument flight ratings were asked to perform a fault-diagnosis task for which they had relevant domain knowledge. The pilots were asked to think out loud as they requested and interpreted information. Performances were then modeled as the activation and use of a frame system. Cognitive biases, memory distortions and losses, and failures to correctly diagnose the problem were studied in the context of this frame system model.

  13. Natural Radiation for Identification and Evaluation of Risk Zones for Affectation of Activated Faults in Aquifer Overexploited.

    NASA Astrophysics Data System (ADS)

    Ramos-Leal, J.; Lopez-Loera, H.; Carbajal-Perez, N.

    2007-05-01

    In basins as Mexico, Michoacán, Guanajuato, Queretaro, Aguascalientes and San Luis Potosi, the existence of faults and fractures have affected the urban infrastructure, lines of conduction of drinkable water, pipelines, etc., that when not being identified and considered, they don't reflect the real impact that these cause also to the aquifer system, modifying the permeability of the means and in occasions they work as preferential conduits that communicate hydraulically potentially to the aquifer with substances pollutants (metals, fertilizers, hydrocarbons, waste waters, etc.) located in the surface. In the Valley of San Luis Potosi, Villa of Reyes, Arista, Ahualulco and recently The Huizache-Matehuala is being strongly affected by faulting and supposedly due cracking to subsidence, however, the regional tectonic could also be the origin of this phenomenon. To know the origin of the faults and affectation to the vulnerability of the aquifer few works they have been carried out in the area. A preliminary analysis indicates that it is possible that a tectonic component is affecting the area and that the vulnerability of the aquifer in that area you this increasing. Before such a situation, it is necessary to carry out the isotopic study of the same one, for this way to know among other things, isotopic characterization, recharge places and addresses of flow of the groundwater; quality of waters and the behavior hydrochemistry with relationship to the faults. High radon values were measured in San Luis Potosi Valley, the natural source of radon could be the riolites and however, these are located to almost a once thousand meters deep for what the migration of the gas is not very probable. The anomalies radiometrics was not correlation with the faults in this case. In some areas like the Valley of Celaya, the origin of the structures and the tectonic activity in the area was confirmed, identifying the structural arrangement of the faulting, the space relationships

  14. Paleoseismologic and geomorphic constraints to the deformation style and activity of the Cittanova Fault (southern Calabria, Italy)

    NASA Astrophysics Data System (ADS)

    Peronace, Edoardo; Della Seta, Marta; Fredi, Paola; Galli, Paolo; Giaccio, Biagio; Messina, Paolo; Troiani, Francesco

    2016-04-01

    The western side of Southern Calabria is the epicentral region of the strongest earthquakes of Italy. These are mainly generated by extensional faults which are still poorly investigated and/or parameterized. In this study, we explore the potential of the combined analysis of geomorphic markers, stream network morphometry and paleosimological investigations, aimed at identifying and time-constraining the surface effects of the Calabrian seismogenic faults. In this perspective, we presents results from i) plano-altimetric analysis of geomorphic markers related to active tectonics (such as marine and fluvial terraces), ii) paleoseismological investigations, and iii) time-dependent river basin and long-profile metrics of the Cittanova Fault (CF). The CF, responsible for the catastrophic Mw 7.0 earthquake of 5 February 1783, is a N220° striking, 30 km-long normal fault that downthrows the crystalline-metamorphic basement of the Aspromonte massif (~1000 m asl) below the Gioia Tauro Plain, to elevations of ~500-800 m bsl. Radiocarbon dating allowed us to ascribe the depostion of a major terraced alluvial fan (Cittanova-Taurianova terrace, TAC) to the early Last Glacial Maximum (LGM) and to date the avulsion of the depositional top surface of TAC to 28 ka. As we have found remnants of the TAC also in the CF footwall offset by 12-17 m, we estimate a vertical slip rate of 0.6 ± 0.1 mm/yr for the past 28 ka. Paleoseismological data across the fault scarp evidenced at least three surface ruptures associated to ~Mw 7.0 paleoearthquakes prior to the 1783 event. The recurrence time (~3.2 kyr) is rather longer than other Apennine normal faults (0.3-2.4 kyr), whereas it is consistent with the low slip rate of CF for the late Upper Pleistocene (0.6 mm/yr). On a longer time scale, the spatial configuration of river basin morphometry evidenced the morphodynamic rensponse to the higher slip in the central sector of CF. Furthermore, long-profile metrics, and in particular the spatial

  15. Seismotectonics of the Gulf of Cadiz and Horseshoe Abyssal Plain - active faulting in continental and oceanic mantle

    NASA Astrophysics Data System (ADS)

    Grevemeyer, Ingo; Matias, Luis

    2013-04-01

    In the area to the west of the Gibraltar Arc the plate boundary between Africa and Iberia is poorly defined. The deformation in the area is forced by the slow NW-SE convergence of 4 mm/yr between the oceanic domains of Iberia/Eurasia and Africa and is accommodated over a 200 km broad tectonically-active deformation zone. The region, however, is also characterized by large earthquakes and tsunamis, such as the 1969 Mw=7.9 Horseshoe Abyssal Plain earthquake and the November 1, 1755 Great Lisbon earthquake with an estimated magnitude of Mw~8.5. The exact location of the source of the 1755 Lisbon earthquake is still unknown. Recent work, however, may suggest that the event occurred in the vicinity of the Horseshoe fault, an oblique thrust fault. Further, the area is marked by the presence of compressive structures with a roughly NE-SW orientation and E-W trending, segmented, crustal-scale, strike slip faults that extend from the Gorringe Bank to the Gibraltar arc in the eastern Gulf of Cadiz, which were called "South West Iberian Margin" or SWIM faults. The fault system may mark a developing Eurasia-Africa plate boundary. Two local seismic networks were operated in the area. First, within the framework of TOPOE-EUROPE, a network of 24 ocean bottom seismometers (OBS) monitored the seismicity between January and July 2010 in the northern Gulf of Cadiz to the north of 36°N between 9°30'W and ~7 °W. The second network operated between April and October 2012 14OBS in the vicinity of the Horseshoe fault between 10°W to 11°W, and 35°50'N to 36°10'N. Recordings from the both deployments were supplemented by land stations operated in Portugal and the Gibraltar Arc. The networks provided in the order of 100 locale earthquakes occurring with the networks. In the Gulf of Cadiz, the two largest events of Mw~3.6 where thrust faulting events occurring in the vicinity of the Portimao Bank. With a depth of 40-50 km these events, among others, occurred within the continental

  16. The implication of gouge mineralogy evolution on fault creep: an example from The North Anatolian Fault, Turkey

    NASA Astrophysics Data System (ADS)

    Kaduri, M.; Gratier, J. P.; Renard, F.; Cakir, Z.; Lasserre, C.

    2015-12-01

    Aseismic creep is found along several sections of major active faults at shallow depth, such as the North Anatolian Fault in Turkey, the San Andreas Fault in California (USA), the Longitudinal Valley Fault in Taiwan, the Haiyuan fault in China and the El Pilar Fault in Venezuela. Identifying the mechanisms controlling creep and their evolution with time and space represents a major challenge for predicting the mechanical evolution of active faults, the interplay between creep and earthquakes, and the link between short-term observations from geodesy and the geological setting. Hence, studying the evolution of initial rock into damaged rock, then into gouge, is one of the key question for understanding the origin of fault creep. In order to address this question we collected samples from a dozen well-preserved fault outcrops along creeping and locked sections of the North Anatolian Fault. We used various methods such as microscopic and geological observations, EPMA, XRD analysis, combined with image processing, to characterize their mineralogy and strain. We conclude that (1) there is a clear correlation between creep localization and gouge composition. The locked sections of the fault are mostly composed of massive limestone. The creeping sections comprises clay gouges with 40-80% low friction minerals such as smectite, saponite, kaolinite, that facilitates the creeping. (2) The fault gouge shows two main structures that evolve with displacement: anastomosing cleavage develop during the first stage of displacement; amplifying displacement leads to layering development oblique or sub-parallel to the fault. (3) We demonstrate that the fault gouge result from a progressive evolution of initial volcanic rocks including dissolution of soluble species that move at least partially toward the damage zones and alteration transformations by fluid flow that weaken the gouge and strengthen the damage zone.

  17. Improvements to the FATOLA computer program including added actively controlled landing gear subroutines

    NASA Technical Reports Server (NTRS)

    Mall, G. H.

    1983-01-01

    Modifications to a multi-degree-of-freedom flexible aircraft take-off and landing analysis (FATOLA) computer program, including a provision for actively controlled landing gears to expand the programs simulation capabilities, are presented. Supplemental instructions for preparation of data and for use of the modified program are included.

  18. Active tectonics in southern Xinjiang, China: Analysis of terrace riser and normal fault scarp degradation along the Hotan-Qira fault system

    SciTech Connect

    Avouac, J.P.; Peltzer, G. |

    1993-12-01

    The northern piedmont of the western Kunlun mountains (Xinjiang, China) is marked at its easternmost extremity, south of the Hotan-Qira oases, by a set of normal faults trending N50E for nearly 70 km. Conspicuous on Landsat and SPOT images, these faults follow the southeastern border of a deep flexural basin and may be related to the subsidence of the Tarim platform loaded by the western Kunlun northward overthrust. The Hotan-Qira normal fault system vertically offsets the piedmont slope by 70 m. Highest fault scarps reach 20 m and often display evidence for recent reactivations about 2 m high. Successive stream entrenchments in uplifted footwallls have formed inset terraces. We have leveled topographic profiles across fault scarps and transverse abandoned terrace risers. The state of degradation of each terrace edge has been characterized by a degradation coefficient tau, derived by comparison with analytical erosion models. Edges of highest abandoned terraces yield a degradation coefficient of 33 +/- 4 sq.m. Profiles of cumulative fault scarps have been analyzed in a similar way using synthetic profiles generated with a simple incremental fault scarp model.

  19. Active tectonics in southern Xinjiang, China: Analysis of terrace riser and normal fault scarp degradation along the Hotan-Qira fault system

    NASA Technical Reports Server (NTRS)

    Avouac, Jean-Philippe; Peltzer, Gilles

    1993-01-01

    The northern piedmont of the western Kunlun mountains (Xinjiang, China) is marked at its easternmost extremity, south of the Hotan-Qira oases, by a set of normal faults trending N50E for nearly 70 km. Conspicuous on Landsat and SPOT images, these faults follow the southeastern border of a deep flexural basin and may be related to the subsidence of the Tarim platform loaded by the western Kunlun northward overthrust. The Hotan-Qira normal fault system vertically offsets the piedmont slope by 70 m. Highest fault scarps reach 20 m and often display evidence for recent reactivations about 2 m high. Successive stream entrenchments in uplifted footwallls have formed inset terraces. We have leveled topographic profiles across fault scarps and transverse abandoned terrace risers. The state of degradation of each terrace edge has been characterized by a degradation coefficient tau, derived by comparison with analytical erosion models. Edges of highest abandoned terraces yield a degradation coefficient of 33 +/- 4 sq.m. Profiles of cumulative fault scarps have been analyzed in a similar way using synthetic profiles generated with a simple incremental fault scarp model.

  20. EEG reactions of the human brain in the gradient magnetic field zone of the active geological fault (pilot study)

    NASA Astrophysics Data System (ADS)

    Pobachenko, S. V.; Shitov, A. V.; Grigorjev, P. E.; Sokolov, M. V.; Zubrilkin, A. I.; Vypiraylo, D. N.; Solovjev, A. V.

    2016-12-01

    This paper presents the results of experimental studies of the dynamics of the functional state of a person within the zone of an active geological fault characterized by abnormal spatial distribution of the magnetic- field vector values. It is shown that these geophysical modifications have a pronounced effect on the fluctuations of the electrical activity of the human brain. When the person gets into a zone with abnormal levels of gradient magnetic field in the absence of any subjective sensations, a nonspecific orientation activation reaction is observed, which is characterized by a significant increase in the levels of peak performance in key functional EEG frequency bands.

  1. Tectonic Activity and Processes Preceding the Formation of the Dead Sea Fault Zone

    NASA Astrophysics Data System (ADS)

    Eppelbaum, L. V.; Pilchin, A. N.

    2007-12-01

    Analysis of geological-geophysical data indicates that at the end of the Proterozoic, blocks of the Arabian Shield (AS) were thrust to the north-west onto the crust of the proto-Mediterranean (PM). This was caused by the pushing of oceanic crust from the south-east forming the Najd faults system (NF). This thrusting took place between 630 and 590 Ma, and is confirmed by the offsets between the Yanbu suture of the AS and Allaqi-Sol Hamid suture of the Nubian Shield (NS), the Bi'r Umq suture of AS and Nakasib suture of NS, and parts of the Yanbu and Nabitah sutures of AS. This caused the separation of AS from NS, and AS from the continental crust to north-east of it with its north-western displacement, resulting in opening of the Persian Gulf. This caused the start of deposition of huge amounts of Vendian-Cambrian evaporites in Saudi Arabia, Oman, Persian Gulf, Zagros, central Iran and other regions. The fact of the formation and preservation of the evaporites, and the common similarities in Vendian-Triassic sedimentary cover of Central Iran, Zagros, Taurus, and Arabian Plate (AP) and common Late Proterozoic-Early Paleozioc magmatic activity, show that these regions did not change their position significantly since then. Results of the DESERT project show that the lowermost part of the crust is present east of the Dead Sea Fault Zone (DSFZ), but it is absent west of it. This could be explained by detachment of the bottom part of the crust west of DSFZ during AP thrusting onto the crust of PM. The lithospheric slice discovered by seismic data between Moho and depth of about 55 km in S. Israel could be a remnant of that crust. During the thrusting, the AP overrode the detached slice. The slice was later remelted during formation of the postorogenic magmatic rocks of 590-530 Ma widespread in Jordan. The formation of three dyke swarms in S. Israel (600-540 Ma), widespread dykes in Sinai (590-530 Ma) and AP (590-530 Ma), as well as high-T-low-P metamorphism between 600

  2. Study of Active Faults in the Three Gorges Dam region by Detecting and Relocating Aftershocks

    NASA Astrophysics Data System (ADS)

    Huang, R.; Zhu, L.; Xu, Y.

    2014-12-01

    Seismicity in the Three Gorges Dam (TGD) region and its adjacent areas increased dramatically as the water- level of the TGD reservoir rises since its completion in 2003. Accordingly, many efforts have been put forward to quantify the seismicity and geological hazards in the region. However, the precise detective of earthquakes, especially for the minor ones, remains difficulty because of sparse distribution of permanent seismic stations. From December 2013 to June 2014, we deployed 30 three-component broadband seismic stations in the TGD region. During the deployment, we recorded two earthquakes of magnitudes lager than 5.0, one occurred on December 16th 2013 in Badong and another on March 30th 2014 in Zigui. We firstly used a sliding-window cross-correlation (SCC) detection technique to supplement the events catalog from the China Earthquake Networks Center. Over 500 new events with ML lager than 0.5 were detected. We then relocated 502 events out of the total 987 events using the double-difference (DD) relocation algorithm. We also determined moment tensors of some large earthquakes using gCAP. The results clearly show two active faults along Yangtze River with dips of 50 degrees and 90 degrees to a maximum depth of 10 km, respectively. And they also reveal that water might have permeated to a depth of 6 km corresponds to the interface of sediments and metamorphic basement beneath Zigui Basin. We thus preliminarily judge that the quakes are triggered by local stress adjustment resulting of fluctuation of Three Gorges reservoir's loading.

  3. Earthquake disaster mitigation of Lembang Fault West Java with electromagnetic method

    SciTech Connect

    Widodo

    2015-04-24

    The Lembang fault is located around eight kilometers from Bandung City, West Java, Indonesia. The existence of this fault runs through densely populated settlement and tourism area. It is an active fault structure with increasing seismic activity where the 28 August 2011 earthquake occurred. The seismic response at the site is strongly influenced by local geological conditions. The ambient noise measurements from the western part of this fault give strong implication for a complex 3-D tectonic setting. Hence, near surface Electromagnetic (EM) measurements are carried out to understand the location of the local active fault of the research area. Hence, near surface EM measurements are carried out to understand the location of the local active fault and the top of the basement structure of the research area. The Transientelectromagnetic (TEM) measurements are carried out along three profiles, which include 35 TEM soundings. The results indicate that TEM data give detailed conductivity distribution of fault structure in the study area.

  4. Earthquake disaster mitigation of Lembang Fault West Java with electromagnetic method

    NASA Astrophysics Data System (ADS)

    Widodo

    2015-04-01

    The Lembang fault is located around eight kilometers from Bandung City, West Java, Indonesia. The existence of this fault runs through densely populated settlement and tourism area. It is an active fault structure with increasing seismic activity where the 28 August 2011 earthquake occurred. The seismic response at the site is strongly influenced by local geological conditions. The ambient noise measurements from the western part of this fault give strong implication for a complex 3-D tectonic setting. Hence, near surface Electromagnetic (EM) measurements are carried out to understand the location of the local active fault of the research area. Hence, near surface EM measurements are carried out to understand the location of the local active fault and the top of the basement structure of the research area. The Transientelectromagnetic (TEM) measurements are carried out along three profiles, which include 35 TEM soundings. The results indicate that TEM data give detailed conductivity distribution of fault structure in the study area.

  5. Modeling of fault activation and seismicity by injection directly into a fault zone associated with hydraulic fracturing of shale-gas reservoirs

    EPA Pesticide Factsheets

    LBNL, in consultation with the EPA, expanded upon a previous study by injecting directly into a 3D representation of a hypothetical fault zone located in the geologic units between the shale-gas reservoir and the drinking water aquifer.

  6. Faults in parts of north-central and western Houston metropolitan area, Texas

    USGS Publications Warehouse

    Verbeek, Earl R.; Ratzlaff, Karl W.; Clanton, Uel S.

    1979-01-01

    Hundreds of residential, commercial, and industrial structures in the Houston metropolitan area have sustained moderate to severe damage owing to their locations on or near active faults. Paved roads have been offset by faults at hundreds of locations, butted pipelines have been distorted by fault movements, and fault-induced gradient changes in drainage lines have raised concern among flood control engineers. Over 150 faults, many of them moving at rates of 0.5 to 2 cm/yr, have been mapped in the Houston area; the number of faults probably far exceeds this figure.This report includes a map of eight faults, in north-central and western Houston, at a scale useful for land-use planning. Seven of the faults, are known, to be active and have caused considerable damage to structures built on or near them. If the eighth fault is active, it may be of concern to new developments on the west side of Houston. A ninth feature shown on the map is regarded only as a possible fault, as an origin by faulting has not been firmly established.Seismic and drill-hold data for some 40 faults, studied in detail by various investigators have verified connections between scarps at the land surface and growth faults in the shallow subsurface. Some scarps, then, are known to be the surface manifestations of faults that have geologically long histories of movement. The degree to which natural geologic processes contribute to current fault movement, however, is unclear, for some of man’s activities may play a role in faulting as well.Evidence that current rates of fault movement far exceed average prehistoric rates and that most offset of the land surface in the Houston area has occurred only within the last 50 years indirectly suggest that fluid withdrawal may be accelerating or reinitiating movement on pre-existing faults. This conclusion, however, is based only on a coincidence in time between increased fault activity and increased rates of withdrawal of water, oil, and gas from

  7. Active tectonics of the Devils Mountain Fault and related structures, northern Puget Lowland and eastern Strait of Juan de Fuca region, Pacific Northwest

    USGS Publications Warehouse

    Johnson, Samuel Y.; Dadisman, Shawn V.; Mosher, David C.; Blakely, Richard J.; Childs, Jonathan R.

    2001-01-01

    Information from marine high-resolution and conventional seismic-reflection surveys, aeromagnetic mapping, coastal exposures of Pleistocene strata, and lithologic logs of water wells is used to assess the active tectonics of the northern Puget Lowland and eastern Strait of Juan de Fuca region of the Pacific Northwest. These data indicate that the Devils Mountain Fault and the newly recognized Strawberry Point and Utsalady Point faults are active structures and represent potential earthquake sources.

  8. Cenozoic Tectonic Activity of the "Passive" North America Margin: Evidence for Cenozoic Activity on Mesozoic or Paleozoic Faults

    NASA Astrophysics Data System (ADS)

    Nedorub, O. I.; Knapp, C. C.

    2012-12-01

    The tectonic history of the Eastern North American Margin (ENAM) incorporates two cycles of continental assembly, multiple pulses of orogeny, rifting, and post-rift geodynamic evolution. This is reflected in the heterogeneous lithosphere of the ENAM which contains fault structures originated in Paleozoic to Mesozoic eras. The South Georgia Rift basin is probably the largest Mesozoic graben within its boundaries that is associated with the breakup of Pangea. It is composed of smaller sub-basins which appear to be bounded by high-angle normal faults, some of which may have been inverted in late Cretaceous and Cenozoic eras. Paleozoic structures may have been reactivated in Cenozoic time as well. The ENAM is characterized by N-NE maximum horizontal compressive stress direction. This maximum compressional stress field is sub-parallel to the strike of the Atlantic Coast province fault systems. Camden, Augusta, Allendale, and Pen Branch faults are four of the many such reactivated faults along the southern part of ENAM. These faults are now buried under the 0-400 m of loosely consolidated Cretaceous and Cenozoic age sediments and thus are either only partially mapped or currently not recognized. Some of the objectives of this study are to map the subsurface expression and geometry of these faults and to investigate the post Cretaceous deformation and possible causes of fault reactivation on a passive margin. This study employs an integrated geophysical approach to investigate the upper 200 m of identified locations of the above mentioned faults. 2-D high-resolution shallow seismic reflection and refraction methods, gravity surveys, GPR, 2-D electrical resistivity and well data are used for analyses and interpretation. Preliminary results suggest that Camden fault shows signs of Cenozoic reactivation through an approximately 30 m offset NW side up mainly along a steeply dipping fault zone in the basal contact of Coastal Plain sediments with the Carolina Piedmont. Drill

  9. Millennial Slip Rate of the Longitudinal Valley Fault From River Terraces: Implications for Convergence Across the Active Suture of Eastern Taiwan

    NASA Astrophysics Data System (ADS)

    Shyu, J. H.; Sieh, K.; Avouac, J.; Chen, W.; Chen, Y.

    2005-12-01

    Interpreting a geomorphic analysis of fluvial terraces in the hanging-wall block of a major active fault in Taiwan by means of a structural model, we have created a model for the creation of a lithospheric suture that may have broader application. The Longitudinal Valley fault is a key element in the active tectonics of Taiwan. It is the principal structure accommodating convergence across the eastern of the two active sutures of the Taiwan orogeny. To understand more precisely its role in the suturing process, we analyzed fluvial terraces along the Hsiukuluan River, which is the only river that cuts across the Coastal Range of eastern Taiwan, in the hanging-wall block of the Longitudinal Valley fault. This allowed us to determine both the subsurface geometry and the millennial slip rate of the fault. The uplift pattern of the Hsiukuluan River terraces is consistent with a fault-bend fold model. Our analysis yields a listric geometry for the Longitudinal Valley fault in its uppermost 2.5 km, with dips decreasing downdip from about 50° to about 30°. The maximum dip-slip component of the Holocene slip rate of the fault is about 23 mm/yr, which yields a maximum horizontal shortening rate of about 25.6 mm/yr in the direction of plate convergence. This rate is far less than the 40 mm/yr rate of shortening across the Longitudinal Valley derived from GPS measurements. The discrepancy may reflect an actual difference in millennial and decadal rates of convergence. An alternative explanation, however, is that the discrepancy is accommodated by a combination of subsidence of the Longitudinal Valley and slip on the Central Range fault, the other active fault of the suture. The shallow listric geometry of the Longitudinal Valley fault at the Hsiukuluan River valley differs markedly from the deep listric geometry illuminated by earthquake hypocenters near Chihshang, about 45 km to the south. We propose a model whereby this fundamental along-strike difference in geometry of

  10. Managing the Risk of Triggered Seismicity: Can We Identify (and Avoid) Potentially Active Faults? - A Practical Case Study in Oklahoma

    NASA Astrophysics Data System (ADS)

    Zoback, M. D.; Alt, R. C., II; Walsh, F. R.; Walters, R. J.

    2014-12-01

    It is well known that throughout the central and eastern U.S. there has been a marked increase in seismicity since 2009, at least some of which appears to increased wastewater injection. No area has seen a greater increase in seismicity than Oklahoma. In this paper, we utilize newly available information on in situ stress orientation and relative magnitudes, the distribution of high volume injection wells and knowledge of the intervals used for waste water disposal to identify the factors potentially contributing to the occurrence of triggered seismicity. While there are a number of sites where in situ stress data has been successfully used to identify potentially active faults, we are investigating whether this methodology can be implemented throughout a state utilizing the types of information frequently available in areas of oil and gas development. As an initial test of this concept, we have been compiling stress orientation data from wells throughout Oklahoma provided by private industry. Over fifty new high quality data points, principally drilling-induced tensile fractures observed in image logs, result in a greatly improved understanding of the stress field in much of the state. A relatively uniform ENE direction of maximum compressive stress is observed, although stress orientations (and possibly relative stress magnitudes) differ in the southern and southwestern parts of the state. The proposed methodology can be tested in the area of the NE-trending fault that produced the M 5+ earthquakes in the Prague, OK sequence in 2011, and the Meers fault in southwestern OK, that produced a M~7 reverse faulting earthquake about 1100 years ago. This methodology can also be used to essentially rule out slip on other major faults in the area, such as the ~N-S trending Nemaha fault system. Additional factors leading to the occurrence of relatively large triggered earthquakes in Oklahoma are 1) the overall increase in injection volumes throughout the state in recent

  11. Activation of Fault Structures South of the La Habra Earthquake Rupture As Evidenced By UAVSAR Imaging

    NASA Astrophysics Data System (ADS)

    Donnellan, A.; Parker, J. W.; Grant Ludwig, L.; Hauksson, E.

    2014-12-01

    The 28 March, 2014 M 5.2 La Habra earthquake occurred on a northeast striking, northwest dipping left-lateral oblique thrust fault at the northeastern margin of the LA Basin, where regional right-lateral shear is accommodated by major northwest trending faults of the Peninsular Ranges, and north-south shortening is accommodated by north-dipping thrust faults and east-west trending folds of the Transverse Ranges. The La Habra mainshock location and focal mechanism is northwest of but sub-parallel to the Puente Hills thrust fault. Relocated seismicity highlights a northeast-trending rupture plane consistent with the magnitude and focal mechanism of the event. NASA's UAVSAR L-Band radar instrument was flown for north and south looking lines before the earthquake on 22 January 2014. The north looking line was reflown three days after the earthquake on 31 March, 2014, and the south looking line was reflown a week later on 4 April 2014. The UAVSAR Repeat Pass Interferogram (RPI) products show deformation consistent with the location of the mainshock beneath the town of La Habra. The results also show considerable aseismic northward horizontal deformation with minor uplift in the West Coyote Hills, south of the relocated seismicity. Inversion of the combined interferograms is consistent with south dipping low-angle (7°) shallow slip that corresponds to bedding plane attitudes and a mapped unconformity. The entire West Coyote Hills show 37 mm of modeled northward slip with an additional 34 mm of modeled slip concentrated near the Coyote Hills Park northeast of the intersection of Rosecrans Avenue and North Gilbert Street. A narrow band of shortening was also observed with UAVSAR, and confirmed with on-the-ground field observations, at the Trojan Way Kink Band, nearly one fault dimension southwest of the main rupture.

  12. Quaternary evolution of the Marrakech High Atlas and morphotectonic evidence of activity along the Tizi N'Test Fault, Morocco

    NASA Astrophysics Data System (ADS)

    Delcaillau, Bernard; Laville, Edgard; Amhrar, Mostafa; Namous, Mustapha; Dugué, Olivier; Pedoja, Kevin

    2010-06-01

    Here, we consider the Ourika and Rheraia drainage basins on the Tizi N'Test Fault zone in the mountains of the Marrakech High Atlas (western Morocco) with regard to Late Pleistocene tectonic activity. New insights into geomorphological changes in drainage patterns and related landforms are based on geological fieldwork in conjunction with DEM analysis. Lithological and structural data combined with certain geomorphometric indices provide clues to the ongoing uplift of Quarternary surfaces in this region. Five geomorphological indices are utilized: 1) drainage network, 2) shape of stream long profiles, 3) hypsometric integral and curves, 4) valley-floor width valley-height ratio (Vf index), and 5) stream gradient index (SL index). We also considered the temporal evolution of alluvial-deposit complexes with diverse lithofacies, such as debris flows, channel gravels, rockslide-debris avalanche, stratified slope deposits, terrace gravels, and fan deposits in the Ourika and Rheraia valleys. Pleistocene talus deposits and fluvial sediments are offset by the Tizi N'Test Fault in the Upper Ourika and Upper Rheraia valleys. Such deformation of thick, continental deposits strongly points to thrust reactivation along the Tizi N'Test Fault. We define the chronology and overall aggradation phases, or lateral incision phases, showing how they are the consequences of variations in tectonic uplift and climate. As a result, we are better able to access recent morphotectonic evolution in part of the Marrakech High Atlas.

  13. Active fault detection and isolation of discrete-time linear time-varying systems: a set-membership approach

    NASA Astrophysics Data System (ADS)

    Mojtaba Tabatabaeipour, Seyed

    2015-08-01

    Active fault detection and isolation (AFDI) is used for detection and isolation of faults that are hidden in the normal operation because of a low excitation signal or due to the regulatory actions of the controller. In this paper, a new AFDI method based on set-membership approaches is proposed. In set-membership approaches, instead of a point-wise estimation of the states, a set-valued estimation of them is computed. If this set becomes empty the given model of the system is not consistent with the measurements. Therefore, the model is falsified. When more than one model of the system remains un-falsified, the AFDI method is used to generate an auxiliary signal that is injected into the system for detection and isolation of faults that remain otherwise hidden or non-isolated using passive FDI (PFDI) methods. Having the set-valued estimation of the states for each model, the proposed AFDI method finds an optimal input signal that guarantees FDI in a finite time horizon. The input signal is updated at each iteration in a decreasing receding horizon manner based on the set-valued estimation of the current states and un-falsified models at the current sample time. The problem is solved by a number of linear and quadratic programming problems, which result in a computationally efficient algorithm. The method is tested on a numerical example as well as on the pitch actuator of a benchmark wind turbine.

  14. Knickpoint series of gullies along the Luoyunshan Piedmont and its relation with fault activity since late Pleistocene

    NASA Astrophysics Data System (ADS)

    Sun, Changbin; Wan, Tianfeng; Xie, Xinsheng; Shen, Xiaoming; Liang, Kuan

    2016-09-01

    The authors surveyed the longitudinal profiles of 28 gullies across the Luoyunshan Piedmont fault (LPF) by differential GPS and dating of sediments well preserved in the typical terraces and obtained 6-level knickpoint series of the gullies along the Luoyunshan Piedmont. The authors compared it with previous studies on the paleo-earthquakes of the LPF revealed by trenches and found that the paleo-earthquake events from knickpoint and trench studies are in good agreement in terms of the time of occurrence and vertical displacement of the fault. It shows studying the paleo-earthquake events of the fault by knickpoint series is feasible. At last, the authors established a more complete paleo-earthquake sequence of the LPF supported by geomorphologic and sedimentary evidence, i.e., six paleo-earthquake events happened on the LPF from about 28,000 years ago; the LPF has the characteristic of quasi-periodic recurrence and the average recurrence interval is 4585 years. The vertical displacement of the paleo-earthquake events is 2.4-3.0 m; according to the empirical equations between co-seismic displacement and earthquake magnitude the magnitude of these events is Ms 7.0-7.5. This study aims to complement and improve the traditional trenching method, provide theoretical and methodological support for the research of active tectonics, and contribute important information for the seismic hazard assessment of the densely populated Linfen area.

  15. Exploring the shallow structure of the San Ramón thrust fault in Santiago, Chile (∼33.5° S), using active seismic and electric methods

    NASA Astrophysics Data System (ADS)

    Díaz, D.; Maksymowicz, A.; Vargas, G.; Vera, E.; Contreras-Reyes, E.; Rebolledo, S.

    2014-01-01

    The crustal-scale west-vergent San Ramón thrust fault system at the foot of the main Andean Cordillera in central Chile is a geologically active structure with Quaternary manifestations of complex surface rupture along fault segments in the eastern border of Santiago city. From the comparison of geophysical and geological observations, we assessed the subsurface structure pattern affecting sedimentary cover and rock-substratum topography across fault scarps, which is critic for evaluating structural modeling and associated seismic hazard along this kind of faults. We performed seismic profiles with an average length of 250 m, using an array of twenty-four geophones (GEODE), and 25 shots per profile, supporting high-resolution seismic tomography for interpreting impedance changes associated to deformed sedimentary cover. The recorded traveltime refractions and reflections were jointly inverted by using a 2-D tomographic approach, which resulted in variations across the scarp axis in both velocities and reflections interpreted as the sedimentary cover-rock substratum topography. Seismic anisotropy observed from tomographic profiles is consistent with sediment deformation triggered by west-vergent thrust tectonics along the fault. Electrical soundings crossing two fault scarps supported subsurface resistivity tomographic profiles, which revealed systematic differences between lower resistivity values in the hanging wall with respect to the footwall of the geological structure, clearly limited by well-defined east-dipping resistivity boundaries. The latter can be interpreted in terms of structurally driven fluid content-change between the hanging wall and the footwall of a permeability boundary associated with the San Ramón fault. The overall results are consistent with a west-vergent thrust structure dipping ∼55° E at subsurface levels in piedmont sediments, with local complexities being probably associated to fault surface rupture propagation, fault-splay and

  16. Exploring the shallow structure of the San Ramón thrust fault in Santiago, Chile (~33.5° S), using active seismic and electric methods

    NASA Astrophysics Data System (ADS)

    Díaz, D.; Maksymowicz, A.; Vargas, G.; Vera, E.; Contreras-Reyes, E.; Rebolledo, S.

    2014-08-01

    The crustal-scale west-vergent San Ramón thrust fault system, which lies at the foot of the main Andean Cordillera in central Chile, is a geologically active structure with manifestations of late Quaternary complex surface rupture on fault segments along the eastern border of the city of Santiago. From the comparison of geophysical and geological observations, we assessed the subsurface structural pattern that affects the sedimentary cover and rock-substratum topography across fault scarps, which is critical for evaluating structural models and associated seismic hazard along the related faults. We performed seismic profiles with an average length of 250 m, using an array of 24 geophones (Geode), with 25 shots per profile, to produce high-resolution seismic tomography to aid in interpreting impedance changes associated with the deformed sedimentary cover. The recorded travel-time refractions and reflections were jointly inverted by using a 2-D tomographic approach, which resulted in variations across the scarp axis in both the velocities and the reflections that are interpreted as the sedimentary cover-rock substratum topography. Seismic anisotropy observed from tomographic profiles is consistent with sediment deformation triggered by west-vergent thrust tectonics along the fault. Electrical soundings crossing two fault scarps were used to construct subsurface resistivity tomographic profiles, which reveal systematic differences between lower resistivity values in the hanging wall with respect to the footwall of the geological structure, and clearly show well-defined east-dipping resistivity boundaries. These boundaries can be interpreted in terms of structurally driven fluid content change between the hanging wall and the footwall of the San Ramón fault. The overall results are consistent with a west-vergent thrust structure dipping ~55° E in the subsurface beneath the piedmont sediments, with local complexities likely associated with variations in fault

  17. Earthquake precursory events around epicenters and local active faults; the cases of two inland earthquakes in Iran

    NASA Astrophysics Data System (ADS)

    Valizadeh Alvan, H.; Mansor, S.; Haydari Azad, F.

    2012-12-01

    The possibility of earthquake prediction in the frame of several days to few minutes before its occurrence has stirred interest among researchers, recently. Scientists believe that the new theories and explanations of the mechanism of this natural phenomenon are trustable and can be the basis of future prediction efforts. During the last thirty years experimental researches resulted in some pre-earthquake events which are now recognized as confirmed warning signs (precursors) of past known earthquakes. With the advances in in-situ measurement devices and data analysis capabilities and the emergence of satellite-based data collectors, monitoring the earth's surface is now a regular work. Data providers are supplying researchers from all over the world with high quality and validated imagery and non-imagery data. Surface Latent Heat Flux (SLHF) or the amount of energy exchange in the form of water vapor between the earth's surface and atmosphere has been frequently reported as an earthquake precursor during the past years. The accumulated stress in the earth's crust during the preparation phase of earthquakes is said to be the main cause of temperature anomalies weeks to days before the main event and subsequent shakes. Chemical and physical interactions in the presence of underground water lead to higher water evaporation prior to inland earthquakes. On the other hand, the leak of Radon gas occurred as rocks break during earthquake preparation causes the formation of airborne ions and higher Air Temperature (AT) prior to main event. Although co-analysis of direct and indirect observation for precursory events is considered as a promising method for future successful earthquake prediction, without proper and thorough knowledge about the geological setting, atmospheric factors and geodynamics of the earthquake-prone regions we will not be able to identify anomalies due to seismic activity in the earth's crust. Active faulting is a key factor in identification of the

  18. Solar attitude control including active nutation damping in a fixed-momentum wheel satellite

    NASA Astrophysics Data System (ADS)

    Azor, Ruth

    1992-08-01

    In geostationary cruise of a momentum biased satellite, it is necessary to stabilize the roll/yaw attitude due to disturbances, caused mainly by solar pressure. This work presents a roll/yaw control, which is obtained by the use of solar arrays and fixed flaps as actuators, with a horizon sensor for roll measurement. The design also includes an active nutation damping.

  19. Solar sail attitude control including active nutation damping in a fixed-momentum wheel satellite

    NASA Technical Reports Server (NTRS)

    Azor, Ruth

    1992-01-01

    In geostationary cruise of a momentum biased satellite, it is necessary to stabilize the roll/yaw attitude due to disturbances, caused mainly by solar radiation pressure. This work presents a roll/yaw control which is obtained by the use of solar arrays and fixed flaps as actuators, with a horizon sensor for roll measurement. The design also includes an active nutation damping.

  20. Implementation of the Project "Including Disabled Senior Citizens in Creative Activities in 2013-2015"

    ERIC Educational Resources Information Center

    Ploch, Leszek

    2015-01-01

    This paper made an attempt to indicate the findings of the author's research from the experiences of the implementation of the project "Including disabled senior citizens in creative activities in 2013-2015". The issues of disabled senior citizens have been an object of interest over the recent years though it still has not had a proper…

  1. Modifying Physical Activities to Include Individuals with Disabilities: A Systematic Approach

    ERIC Educational Resources Information Center

    Menear, Kristi S.; Davis, Tim

    2007-01-01

    Effectively including individuals with disabilities in a physical activity setting can often be a challenge due to constraints related to equipment, class size, curriculum, and the various ability levels of individuals with and without disabilities. However, there are ways the instructor can control the environment and tasks to meet the needs of…

  2. Structure and flow properties of syn-rift border faults: The interplay between fault damage and fault-related chemical alteration (Dombjerg Fault, Wollaston Forland, NE Greenland)

    NASA Astrophysics Data System (ADS)

    Kristensen, Thomas B.; Rotevatn, Atle; Peacock, David C. P.; Henstra, Gijs A.; Midtkandal, Ivar; Grundvåg, Sten-Andreas

    2016-11-01

    Structurally controlled, syn-rift, clastic depocentres are of economic interest as hydrocarbon reservoirs; understanding the structure of their bounding faults is of great relevance, e.g. in the assessment of fault-controlled hydrocarbon retention potential. Here we investigate the structure of the Dombjerg Fault Zone (Wollaston Forland, NE Greenland), a syn-rift border fault that juxtaposes syn-rift deep-water hanging-wall clastics against a footwall of crystalline basement. A series of discrete fault strands characterize the central fault zone, where discrete slip surfaces, fault rock assemblages and extreme fracturing are common. A chemical alteration zone (CAZ) of fault-related calcite cementation envelops the fault and places strong controls on the style of deformation, particularly in the hanging-wall. The hanging-wall damage zone includes faults, joints, veins and, outside the CAZ, disaggregation deformation bands. Footwall deformation includes faults, joints and veins. Our observations suggest that the CAZ formed during early-stage fault slip and imparted a mechanical control on later fault-related deformation. This study thus gives new insights to the structure of an exposed basin-bounding fault and highlights a spatiotemporal interplay between fault damage and chemical alteration, the latter of which is often underreported in fault studies. To better elucidate the structure, evolution and flow properties of faults (outcrop or subsurface), both fault damage and fault-related chemical alteration must be considered.

  3. Fault diagnosis of analog circuits

    NASA Astrophysics Data System (ADS)

    Bandler, J. W.; Salama, A. E.

    1985-08-01

    Theory and algorithms associated with four main categories of modern techniques used to locate faults in analog circuits are presented. These four general approaches are: the fault dictionary (FDA), the parameter identification (PIA), the fault verification (FVA), and the approximation (AA) approaches. The preliminaries and problems associated with the FDA, such as fault dictionary construction, the methods of optimum measurement selection, fault isolation criteria, and efficient methods of fault simulation, are discussed. The PIA techniques that utilize either linear or nonlinear systems of equations for identification of network elements are examined. Description of the FVA includes node-fault diagnosis, branch-fault diagnosis, subnetwork testability conditions, as well as combinatorial techniques, the failure-bound technique, and the network decomposition technique. In the AA, probabilistic methods and optimization-based methods are considered. In addition, the artificial intelligence technique and the different measures of testability are presented. A series of block diagrams is included.

  4. Modelling fault surface roughness and fault rocks thickness evolution with slip: calibration based on field and laboratory data

    NASA Astrophysics Data System (ADS)

    Bistacchi, A.; Tisato, N.; Spagnuolo, E.; Nielsen, S. B.; Di Toro, G.

    2012-12-01

    The architecture and physical properties of fault zones evolve with slip and time. Such evolution, which progressively modifies the type and thickness of fault rocks, the fault surface roughness, etc., controls the rheology of fault zones (seismic vs. aseismic) and earthquakes (main shock magnitude, coseismic slip distribution, stress drop, foreshock and aftershock sequence evolution, etc.). Seismogenic faults exhumed from 2-10 km depth and hosted in different rocks (carbonates, granitoids, etc.) show a (1) self-affine (Hurst exponent H < 1) surface roughness, indicating that faults are smoother at larger wavelengths, and (2) a roughness anisotropy (surfaces are smoother parallel to slip vector) which progressively develops with slip. The second observation suggests that roughness evolution should be related to the production of fault rocks. We developed a wear model in the spatial frequency domain (for consistency with field measurements and for mathematical convenience) which, given an initial surface roughness, predicts the roughness (power spectral density, anisotropy, root mean square, etc.) and the fault rock thickness after a given slip. The model assumes volume conservation and is based on a very general definition of "wear" (including every process that destroys geometrical asperities and produces fault rocks). The output roughness and fault rock thickness depend on two parameters: (1) wear rate and (2) wear products (fault rocks) accumulation rate. To test the model we used surface roughness, fault rock thickness, and slip data collected in the field (Gole Larghe Fault Zone, Italian Southern Alps) and in the lab (rotary shear experiments on different rocks). The model was successful in predicting the first-order evolution of roughness and of fault rock thickness with slip in both natural and experimental datasets. Differences in best-fit model parameters (wear rate and wear products accumulation rate) were satisfactorily explained in terms of different

  5. Incremental Formation of Dolomitic Vein Related To The Uzer Growth Fault Activity (ardeche Margin, Mesozoic Subalpine Basin of France)

    NASA Astrophysics Data System (ADS)

    Léost, I.; Ramboz, C.

    In order to document mass transfers in the Pb-Zn mineralized Ardèche passive mar- gin, two boreholes were drilled 1.2km apart from the Uzer growth fault which marks a limit between the continental plateform and the basin. The synsedimentary activity of the fault from Early Liassic to Bathonian results in a vertical downthrown of 1km to the SE. The basis of the Balazuc borehole core section (BA1, 1730-deep) is highly fracturated which testifies of the fault vicinity (from -1620m to -1730m). At BA1, middle Triassic beds lie unconformably on the Carboniferous rocks at -1669m. In up- per Paleozoic levels and Triassic levels, dolomitic microveins corresponding to either crack-seal, en echelon-cracks or tension gashes, suggest periodically high fluid pres- sure events. We have particularly studied dolomite around -1626m and 1620m major fractures. Most of the dolomite crystals, either in a shaly cement or in microveins, are optically zoned, due to fluid inclusions, matrix impureties and/or Fe-Mn rich bands. The core of crystals from cements are Mg-rich and fluid inclusion poor. The inner part of crystals from veins is locally Fe-rich and with numerous randomly distributed fluid inclusions, and magnesian and fluid inclusion free elsewhere. The outer part of vein and cement crystals are Fe-enriched (type saddle dolomite) and rich in fluid in- clusions underlining the growth zones. At levels -1624m, -1594m and -1581m, fluid inclusions from vein cores yield rather grouped Tmi and Th values (-22.6

  6. Active faulting, 3-D geological architecture and Plio-Quaternary structural evolution of extensional basins in the central Apennine chain, Italy

    NASA Astrophysics Data System (ADS)

    Gori, Stefano; Falcucci, Emanuela; Ladina, Chiara; Marzorati, Simone; Galadini, Fabrizio

    2017-03-01

    The general basin and range Apennine topographic characteristic is generally attributed to the presently active normal fault systems, whose long-term activity (throughout the Quaternary) is supposed to have been responsible for the creation of morphological/structural highs and lows. By coupling field geological survey and geophysical investigations, we reconstructed the 3-D geological model of an inner tectonic basin of the central Apennines, the Subequana Valley, bounded to the northeast by the southern segment of one of the major active and seismogenic normal faults of the Apennines, known as the Middle Aterno Valley-Subequana Valley fault system. Our analyses revealed that, since the late Pliocene, the basin evolved in a double half-graben configuration through a polyphase tectonic development. An early phase, Late Pliocene-Early Pleistocene in age, was controlled by the ENE-WSW-striking and SSE-dipping Avezzano-Bussi fault, that determined the formation of an early depocentre towards the N-NW. Subsequently, the main fault became the NW-SE-striking faults, which drove the formation during the Quaternary of a new fault-related depocentre towards the NE. By considering the available geological information, a similar structural evolution has likely involved three close tectonic basins aligned along the Avezzano-Bussi fault, namely the Fucino Basin, the Subequana Valley, and the Sulmona Basin, and it has been probably experienced by other tectonic basins of the chain. The present work therefore points out the role of pre-existing transverse tectonic structures, inherited by previous tectonic phases, in accommodating the ongoing tectonic deformation and, consequently, in influencing the structural characteristics of the major active normal faults. This has implications in terms of earthquake fault rupture propagation and segmentation. Lastly, the morpho-tectonic setting of the Apennine chain results from the superposition of deformation events whose

  7. Satellite relay telemetry in the surveillance of active volcanoes and major fault zones

    NASA Technical Reports Server (NTRS)

    Eaton, J. P.; Ward, P. L.

    1972-01-01

    A review was made of efforts to develop a dense telemetered microearthquake network to study earthquake mechanics along the San Andreas fault and the strain mechanics of the Kilauea Volcano. The principle elements and objectives of the ERTS-A proposal are outlined. Some of the aspects of the earthquake network and the results obtained from it as well as some promising experiments in computerized record processing are discussed.

  8. A Numerical Hydro-Chemo-Mechanical Model for Fault Activation under Reactive Fluid Flow

    NASA Astrophysics Data System (ADS)

    Pouya, A.; Tounsi, H.; Rohmer, J.

    2015-12-01

    The migration of CO2-rich fluid in fractured rock masses can cause processes such as mineral dissolution and precipitation, chemically induced weakening, which can affect the long-term mechanical and transport properties of the rock mass as well as the stability of fault systems. Some numerical approaches are already available in the literature for modelling the dissolution/precipitation phenomena in fractures (e.g. Yasuhara & Elsworth 2007) as well as subcritical crack propagation (e.g. Park et al. 2007). Generally, the dissolution is supposed to increase the rock porosity and, in this way, decrease the rock strength. Some experimental data are available for the variation of rock strength and stiffness parameters with the porosity and so as a consequence of dissolution process (Bemer et al. 2004). Also the effect of chemical processes on the mechanical stability has been studied and modelled numerically in the framework of continuum materials and the context, in particular, of weathering in underground galleries (Ghabezloo & Pouya 2006). In the context of fault systems, a complete numerical modelling of the stability evolution with the flow of a reactive fluid has not yet been done. In this paper we present a simplified, but complete, set of equations for a whole system of coupled hydro-chemo-mechanical process of reactive fluid flow inside a fault. These equations have been implemented in Porofis, a FEM numerical code specially conceived for HCM processes in porous fractured media. We show how this numerical method allows to model the coupled HCM processes in the fault and the evolution of the mechanical stability in presence of in situ stresses and reactive fluid flow.

  9. Preliminary Results on the Mechanics of the Active Mai'iu Low Angle Normal Fault (Dayman Dome), Woodlark Rift, SE Papua New Guinea

    NASA Astrophysics Data System (ADS)

    Little, T. A.; Boulton, C. J.; Mizera, M.; Webber, S. M.; Oesterle, J.; Ellis, S. M.; Norton, K. P.; Wallace, L. M.; Biemiller, J.

    2015-12-01

    Rapid slip on the Mai'iu low-angle normal fault (LANF) has exhumed a smooth, corrugated fault surface contiguous for >24 km up-dip, rising from near sea level to ~2900 m. The fault emerges from the ground dipping ~21° N and flattens over the crest of the dome to dip south. Geomorphic analysis reveals a progressive back-tilting of the surface during exhumation accompanied by cross-cutting antithetic-sense high-angle faults—features that we attribute to "rolling-hinge" deformation of a once more steeply-dipping fault. Near the scarp base, the footwall exposes mafic mylonites that deformed at ~400-450°C. The younger Mai'iu fault cross-cuts this ductile mylonite zone, with most brittle slip being localized into a ~20 cm-thick, gouge-filled core. Near the range front, active faults bite across both the hangingwall and footwall of the Mai'iu fault and record overprinting across a dying, shallow (<~1 km deep) part of the fault by more optimally oriented, steeper faults. Such depth-dependent locking up of the fault suggests it weakens primarily by friction reduction rather than cohesion loss. Outcrop-scale fractures in the exhumed footwall reflect formation in an Andersonian stress regime. Previous campaign GPS data suggest the fault slips at up to ~1 cm/yr. To improve resolution and test for aseismic creep, we installed 12 GPS sites across the fault trace in 2015. Quantitative XRD indicates the gouges were derived primarily from mafic footwall, containing up to 65% corrensite and saponite. Hydrothermal friction experiments on two gouges from a relict LANF strand were done at varying normal stresses (30-120 MPa), temperatures (50-200oC), and sliding velocities (0.3-100 μm/s). Results reveal very weak frictional strength (μ=0.13-0.15 and 0.20-0.28) and velocity-strengthening behavior conducive to fault creep. At the highest temperatures (T≥150oC) and lowest sliding velocities (<3 μm/s), a transition to velocity-weakening behavior indicates the potential for

  10. Fault interaction and stresses along broad oceanic transform zone: Tjörnes Fracture Zone, north Iceland

    NASA Astrophysics Data System (ADS)

    Homberg, C.; Bergerat, F.; Angelier, J.; Garcia, S.

    2010-02-01

    Transform motion along oceanic transforms generally occurs along narrow faults zones. Another class of oceanic transforms exists where the plate boundary is quite large (˜100 km) and includes several subparallel faults. Using a 2-D numerical modeling, we simulate the slip distribution and the crustal stress field geometry within such broad oceanic transforms (BOTs). We examine the possible configurations and evolution of such BOTs, where the plate boundary includes one, two, or three faults. Our experiments show that at any time during the development of the plate boundary, the plate motion is not distributed along each of the plate boundary faults but mainly occurs along a single master fault. The finite width of a BOT results from slip transfer through time with locking of early faults, not from a permanent distribution of deformation over a wide area. Because of fault interaction, the stress field geometry within the BOTs is more complex than that along classical oceanic transforms and includes stress deflections close to but also away from the major faults. Application of this modeling to the 100 km wide Tjörnes Fracture Zone (TFZ) in North Iceland, a major BOT of the Mid-Atlantic Ridge that includes three main faults, suggests that the Dalvik Fault and the Husavik-Flatey Fault developed first, the Grismsey Fault being the latest active structure. Since initiation of the TFZ, the Husavik-Flatey Fault accommodated most of the plate motion and probably persists until now as the main plate structure.

  11. Fault displacement hazard for strike-slip faults

    USGS Publications Warehouse

    Petersen, M.D.; Dawson, T.E.; Chen, R.; Cao, T.; Wills, C.J.; Schwartz, D.P.; Frankel, A.D.

    2011-01-01

    In this paper we present a methodology, data, and regression equations for calculating the fault rupture hazard at sites near steeply dipping, strike-slip faults. We collected and digitized on-fault and off-fault displacement data for 9 global strikeslip earthquakes ranging from moment magnitude M 6.5 to M 7.6 and supplemented these with displacements from 13 global earthquakes compiled byWesnousky (2008), who considers events up to M 7.9. Displacements on the primary fault fall off at the rupture ends and are often measured in meters, while displacements on secondary (offfault) or distributed faults may measure a few centimeters up to more than a meter and decay with distance from the rupture. Probability of earthquake rupture is less than 15% for cells 200 m??200 m and is less than 2% for 25 m??25 m cells at distances greater than 200mfrom the primary-fault rupture. Therefore, the hazard for off-fault ruptures is much lower than the hazard near the fault. Our data indicate that rupture displacements up to 35cm can be triggered on adjacent faults at distances out to 10kmor more from the primary-fault rupture. An example calculation shows that, for an active fault which has repeated large earthquakes every few hundred years, fault rupture hazard analysis should be an important consideration in the design of structures or lifelines that are located near the principal fault, within about 150 m of well-mapped active faults with a simple trace and within 300 m of faults with poorly defined or complex traces.

  12. Detection of precursory slips on a fault by the quiescence and activation of seismicity relative to the ETAS model and by the anomalous trend of the geodetic time series of distances between GPS stations around the fault

    NASA Astrophysics Data System (ADS)

    Ogata, Y.

    2006-12-01

    This paper is concerned with the detection of precursory slip on a rupturing fault, supported by both seismic and geodetic records. Basically, the detection relies on the principle that, assuming precursory slip on the rupturing fault, the seismic activity around the fault should be enhanced or reduced in the zones where increment of the Coulomb failure stress (CFS) is positive or negative, respectively. However, any occurring event also affects the stress changes in neighboring regions, which can trigger further aftershock clusters. Whereas such stress transfers are too difficult to be computed precisely, due to the unknown complex fault system, the ordinary short-term occurrence rate of earthquakes in a region is easily predicted using the ETAS model of triggering seismicity; and any anomalous seismic activity, such as quiescence and activation, can be quantified by identifying a significant deviation from the predicted rate. Such anomalies are revealed to have occurred during several years leading up to the 2004 Chuetsu Earthquake of M6.8, central Honshu, and also the 2005 Western Fukuoka-Ken-Oki Earthquake of M7.0, Kyushu, Japan. Quiescence and activation in the regions coincided with negative and positive increments of the CFS, respectively, and were probably transferred from possible aseismic slips on the focal fault plane. Such slips are further supported by transient crustal movement around the source preceding the rupture. Time series records of the baseline distances between the permanent GPS stations deviated from the predicted trends, with the deviations consistent with the coseismic horizontal displacements of the stations due to these earthquakes. References Ogata, Y. (2006) Report of the Coordinating Committee for Earthquake Prediction, 76 (to appear, in Japanese).

  13. Aerial photographic interpretation of lineaments and faults in late Cenozoic deposits in the eastern parts of the Saline Valley 1:100, 000 quadrangle, Nevada and California, and the Darwin Hills 1:100, 000 quadrangle, California

    SciTech Connect

    Reheis, M.C.

    1991-09-01

    Faults and fault-related lineaments in Quaternary and late Tertiary deposits in the southern part of the Walker Lane are potentially active and form patterns that are anomalous compared to those in most other areas of the Great Basin. Two maps at a scale of 1:100,000 summarize information about lineaments and faults in the area around and southwest of the Death Valley-Furnace Creek fault system based on extensive aerial-photo interpretation, limited field interpretation, limited field investigations, and published geologic maps. There are three major fault zones and two principal faults in the Saline Valley and Darwin Hills 1:100,000 quadrangles. (1) The Death Valley-Furnace Creek fault system and (2) the Hunter Mountain fault zone are northwest-trending right-lateral strike-slip fault zones. (3) The Panamint Valley fault zone and associated Towne Pass and Emigrant faults are north-trending normal faults. The intersection of the Hunter Mountain and Panamint Valley fault zones is marked by a large complex of faults and lineaments on the floor of Panamint Valley. Additional major faults include (4) the north-northwest-trending Ash Hill fault on the west side of Panamint Valley, and (5) the north-trending range-front Tin Mountain fault on the west side of the northern Cottonwood Mountains. The most active faults at present include those along the Death Valley-Furnace Creek fault system, the Tin Mountain fault, the northwest and southeast ends of the Hunter Mountain fault zone, the Ash Hill fault, and the fault bounding the west side of the Panamint Range south of Hall Canyon. Several large Quaternary landslides on the west sides of the Cottonwood Mountains and the Panamint Range apparently reflect slope instability due chiefly to rapid uplift of these ranges. 16 refs.

  14. Fault segment linkage and growth of the Polopos transpressive fault zone and its influence on Pleistocene drainage captures (southeastern Betics).

    NASA Astrophysics Data System (ADS)

    Giaconia, F.; Booth-Rea, G.; Martínez-Martínez, J. M.; Azañón, J. M.; Villegas, I.

    2012-04-01

    The Polopos fault zoneis a dextral-reverse fault-system that developed under Neogene to Quaternary N/S to NNW/SSE convergence between Africa and Iberia. This fault zone is formed by three main fault segments, the North and South Gafarillos dextral strike-slip faults, and the North Alhamilla reverse fault. The whole fault zone with an approximate length of 30 km has an E/W to ESE/WNW orientation and helicoidal geometry that permits the transfer of oblique SE-directed shortening in Sierra Cabrera to NW-directed shortening along the North Alhamilla reverse fault via vertical dextral Gafarillos fault segments, in between. The north Alhamilla reverse fault to the west of the system produces a fault-propagation fold in the hangingwall and an overturned fold in the footwall cutting through early Tortonian turbidites and folded Quaternary alluvial fans at the north Alhamilla mountain front. The Quaternary paleo-topographic surface formed by the alluvial fan has been displaced approximately 100 m by reverse faulting after 400 - 70 ky with a slip rate ranging between 0.25 and 1.4 mm yr-1. The South Gafarillos fault includes several N90°-110°E-striking segments with dextral and reverse-dextral kinematics. This fault cuts through the southeastern limb of the Alhamilla anticline by a fault segment that separates the basement from Messinian sediments, meanwhile other segments in the Nijar basin further south cut through Pleistocene river strath-terraces.. During the late Miocene the locus of dextral displacement occurred along the North Gafarillos fault segment that linked to a reverse fault segment at the northeast of the Sierra Alhamilla . The North Gafarillos fault segment and its associated mountain front was sealed by Messinian reefs. Since the Messinian, recent fault activity migrated towards the south forming the South Gafarillos fault segments. Fault segment migration displaced the active oblique strike-slip-related mountain fronts from the north towards the southeast

  15. High-resolution 3D seismic reflection imaging across active faults and its impact on seismic hazard estimation in the Tokyo metropolitan area

    NASA Astrophysics Data System (ADS)

    Ishiyama, Tatsuya; Sato, Hiroshi; Abe, Susumu; Kawasaki, Shinji; Kato, Naoko

    2016-10-01

    We collected and interpreted high-resolution 3D seismic reflection data across a hypothesized fault scarp, along the largest active fault that could generate hazardous earthquakes in the Tokyo metropolitan area. The processed and interpreted 3D seismic cube, linked with nearby borehole stratigraphy, suggests that a monocline that deforms lower Pleistocene units is unconformably overlain by middle Pleistocene conglomerates. Judging from structural patterns and vertical separation on the lower-middle Pleistocene units and the ground surface, the hypothesized scarp was interpreted as a terrace riser rather than as a manifestation of late Pleistocene structural growth resulting from repeated fault activity. Devastating earthquake scenarios had been predicted along the fault in question based on its proximity to the metropolitan area, however our new results lead to a significant decrease in estimated fault length and consequently in the estimated magnitude of future earthquakes associated with reactivation. This suggests a greatly reduced seismic hazard in the Tokyo metropolitan area from earthquakes generated by active intraplate crustal faults.

  16. Faults on Skylab imagery of the Salton Trough area, Southern California

    NASA Technical Reports Server (NTRS)

    Merifield, P. M.; Lamar, D. L. (Principal Investigator)

    1975-01-01

    The author has identified the following significant results. Large segments of the major high angle faults in the Salton Trough area are readily identifiable in Skylab images. Along active faults, distinctive topographic features such as scarps and offset drainage, and vegetation differences due to ground water blockage in alluvium are visible. Other fault-controlled features along inactive as well as active faults visible in Skylab photography include straight mountain fronts, linear valleys, and lithologic differences producing contrasting tone, color or texture. A northwestern extension of a fault in the San Andreas set, is postulated by the regional alignment of possible fault-controlled features. The suspected fault is covered by Holocene deposits, principally windblown sand. A northwest trending tonal change in cultivated fields across Mexicali Valley is visible on Skylab photos. Surface evidence for faulting was not observed; however, the linear may be caused by differences in soil conditions along an extension of a segment of the San Jacinto fault zone. No evidence of faulting could be found along linears which appear as possible extensions of the Substation and Victory Pass faults, demonstrating that the interpretation of linears as faults in small scale photography must be corroborated by field investigations.

  17. Solar sail attitude control including active nutation damping in a fixed-momentum wheel satellite

    NASA Astrophysics Data System (ADS)

    Azor, Ruth

    1992-02-01

    In the geostationary cruise of a momentum biased satellite, it is necessary to stabilize the roll/yaw attitude due to disturbances caused by solar radiation pressure. This work presents a roll/yaw control system with a horizon sensor for roll measurement. Roll/yaw control is obtained by the use of solar arrays and fixed flaps as actuators. The design also includes an active nutation damping method.

  18. Morphostructural study of the Belledonne faults system (French Alps).

    NASA Astrophysics Data System (ADS)

    Billant, Jérémy; Bellier, Olivier; Hippolyte, Jean-Claude; Godard, Vincent; Manchuel, Kevin

    2016-04-01

    The NE trending Belledonne faults system, located in the Alps, is a potentially active faults system that extends from the Aiguilles Rouges and Mont Blanc massifs in the NE to the Vercors massif in the SW (subalpine massifs). It includes the Belledonne border fault (BBF), defined by an alignment of micro earthquakes (ML≤3.5) along the eastern part of the Grésivaudan valley (Thouvenot et al., 2003). Focal mechanisms and their respective depths tend to confirm a dextral strike-slip faulting at crustal scale. In the scope of the Sigma project (http://projet-sigma.com/index.html, EDF), this study aims at better constraining the geometry, kinematic and seismogenic potential of the constitutive faults of the Belledonne fault system, by using a multidisciplinary approach that includes tectonics, geomorphology and geophysics. Fault kinematic analysis along the BBF (Billant et al., 2015) and the Jasneuf fault allows the determination of a strike-slip tectonic regime characterised by an ENE trending σ1 stress axes, which is consistent with stress state deduced from the focal mechanisms. Although no morphological anomalies could be related to recent faulting along the BBF, new clues of potential Quaternary deformations were observed along the other faults of the system: -right lateral offset of morphologic markers (talwegs...) along the NE trending Arcalod fault located at the north-eastern terminations of the BBF; -left lateral offset of the valley formed by the Isère glacier along the NW trending Brion fault which is consistent with its left-lateral slip inferred from the focal mechanisms; -fault scarps and right lateral offsets of cliffs bordering a calcareous plateau and talwegs along the four fault segments of the NE trending Jasneuf fault located at the south-western termination of the BBF in the Vercors massif. Some offsets were measured using a new method that does not require the identification of piercing points and take advantage of the high resolution

  19. Mimetics of caloric restriction include agonists of lipid-activated nuclear receptors.

    PubMed

    Corton, J Christopher; Apte, Udayan; Anderson, Steven P; Limaye, Pallavi; Yoon, Lawrence; Latendresse, John; Dunn, Corrie; Everitt, Jeffrey I; Voss, Kenneth A; Swanson, Cynthia; Kimbrough, Carie; Wong, Jean S; Gill, Sarjeet S; Chandraratna, Roshantha A S; Kwak, Mi-Kyoung; Kensler, Thomas W; Stulnig, Thomas M; Steffensen, Knut R; Gustafsson, Jan-Ake; Mehendale, Harihara M

    2004-10-29

    The obesity epidemic in industrialized countries is associated with increases in cardiovascular disease (CVD) and certain types of cancer. In animal models, caloric restriction (CR) suppresses these diseases as well as chemical-induced tissue damage. These beneficial effects of CR overlap with those altered by agonists of nuclear receptors (NR) under control of the fasting-responsive transcriptional co-activator, peroxisome proliferator-activated co-activator 1alpha (PGC-1alpha). In a screen for compounds that mimic CR effects in the liver, we found statistically significant overlaps between the CR transcript profile in wild-type mice and the profiles altered by agonists of lipid-activated NR, including peroxisome proliferator-activated receptor alpha (PPARalpha), liver X receptor, and their obligate heterodimer partner, retinoid X receptor. The overlapping genes included those involved in CVD (lipid metabolism and inflammation) and cancer (cell fate). Based on this overlap, we hypothesized that some effects of CR are mediated by PPARalpha. As determined by transcript profiling, 19% of all gene expression changes in wild-type mice were dependent on PPARalpha, including Cyp4a10 and Cyp4a14, involved in fatty acid omega-oxidation, acute phase response genes, and epidermal growth factor receptor but not increases in PGC-1alpha. CR protected the livers of wild-type mice from damage induced by thioacetamide, a liver toxicant and hepatocarcinogen. CR protection was lost in PPARalpha-null mice due to inadequate tissue repair. These results demonstrate that PPARalpha mediates some of the effects of CR and indicate that a pharmacological approach to mimicking many of the beneficial effects of CR may be possible.

  20. Geomorphic expression of strike-slip faults: field observations vs. analog experiments: preliminary results

    NASA Astrophysics Data System (ADS)

    Hsieh, S. Y.; Neubauer, F.; Genser, J.

    2012-04-01

    The aim of this project is to study the surface expression of strike-slip faults with main aim to find rules how these structures can be extrapolated to depth. In the first step, several basic properties of the fault architecture are in focus: (1) Is it possible to define the fault architecture by studying surface structures of the damage zone vs. the fault core, particularly the width of the damage zone? (2) Which second order structures define the damage zone of strike-slip faults, and how relate these to such reported in basement fault strike-slip analog experiments? (3) Beside classical fault bend structures, is there a systematic along-strike variation of the damage zone width and to which properties relates the variation of the damage zone width. We study the above mentioned properties on the dextral Altyn fault, which is one of the largest strike-slip on Earth with the advantage to have developed in a fully arid climate. The Altyn fault includes a ca. 250 to 600 m wide fault valley, usually with the trace of actual fault in its center. The fault valley is confined by basement highs, from which alluvial fans develop towards the center of the fault valley. The active fault trace is marked by small scale pressure ridges and offset of alluvial fans. The fault valley confining basement highs are several kilometer long and ca. 0.5 to 1 km wide and confined by rotated dextral anti-Riedel faults and internally structured by a regular fracture pattern. Dextral anti-Riedel faults are often cut by Riedel faults. Consequently, the Altyn fault comprises a several km wide damage zone. The fault core zone is a barrier to fluid flow, and the few springs of the region are located on the margin of the fault valley implying the fractured basement highs as the reservoir. Consequently, the southern Silk Road was using the Altyn fault valley. The preliminary data show that two or more orders of structures exist. Small-scale develop during a single earthquake. These finally

  1. Molecular mechanisms of action of the soy isoflavones includes activation of promiscuous nuclear receptors. A review.

    PubMed

    Ricketts, Marie-Louise; Moore, David D; Banz, William J; Mezei, Orsolya; Shay, Neil F

    2005-06-01

    Consumption of soy has been demonstrated to reduce circulating cholesterol levels, most notably reducing low-density lipoprotein (LDL) cholesterol levels in hypercholesterolemic individuals. The component or components that might be responsible for this effect is still a matter of debate or controversy among many researchers. Candidate agents include an activity of soy protein itself, bioactive peptides produced during the digestive process, or the soy isoflavones. Although soy intake may provide other health benefits including preventative or remediative effects on cancer, osteoporosis and symptoms of menopause, this review will focus on isoflavones as agents affecting lipid metabolism. Isoflavones were first discovered as a bioactive agent disrupting estrogen action in female sheep, thereby earning the often-used term 'phytoestrogens'. Subsequent work confirmed the ability of isoflavones to bind to estrogen receptors. Along with the cholesterol-lowering effect of soy intake, research that is more recent has pointed to a beneficial antidiabetic effect of soy intake, perhaps mediated by soy isoflavones. The two common categories of antidiabetic drugs acting on nuclear receptors known as peroxisome proliferator activated receptors (PPARs) are the fibrates and glitazones. We and others have recently asked the research question 'do the soy isoflavones have activities as either "phytofibrates" or "phytoglitazones"?' Such an activity should be able to be confirmed both in vivo and in vitro. In both the in vivo and in vitro cases, this action has indeed been confirmed. Further work suggests a possible action of isoflavones similar to the nonestrogenic ligands that bind the estrogen-related receptors (ERRs). Recently, these receptors have been demonstrated to contribute to lipolytic processes. Finally, evaluation of receptor activation studies suggests that thyroid receptor activation may provide additional clues explaining the metabolic action of isoflavones. The recent

  2. Quaternary tectonic activity in NW Jordan: Insights for a new model of transpression-transtension along the southern Dead Sea Transform Fault

    NASA Astrophysics Data System (ADS)

    Al-Awabdeh, M.; Pérez-Peña, J. V.; Azañón, J. M.; Booth-Rea, G.; Abed, A.; Atallah, M.; Galve, J. P.

    2016-12-01

    The Dead Sea Transform Fault (DSTF) constitutes the transform plate boundary between the African and Arabian plates. The southern part of this fault has been traditionally divided into two main segments, the Wadi Araba Fault (WAF) and the Jordan Valley Fault (JVF), connected through the Dead Sea continental pull-apart basin. Active tectonic studies in NW Jordan have traditionally focused on these DSTF structures and have neglected other prominent structures in the region, such as the Amman Hallabat Structure (AHS) and Shueib Structure (SHS) fault systems, which have been considered inactive since the Cretaceous. However, some recent studies have suggested a possible local reactivation of the southern parts of these structures. In this work, we carried out a detailed geological study of the NE Dead Sea Basin to analyze the Quaternary activity of the AHS and SHS based on field observations and structural analyses. Our findings have revealed that the AHS and SHS structures present clear Quaternary activity and accommodate a small part of the deformation of the southern DSTF. In the Quaternary, the southwestern part of the AHS has acted as the northernmost continuation of the WAF, whereas the SHS has acted as a transfer fault associated with NW-SE normal faults with low to moderate throws (meters to decameters) that connect this structure to the JVF. These NW-SE normal faults constitute the northeastern border of the Dead Sea depression (Jericho Valley). They produce a topographic front and separate the sediments of the Jordan Valley in the hanging wall from the Mesozoic sedimentary sequence located in the footwall.

  3. Detection of Creep Displacement by DInSAR using TerraSAR-X data around Active Fault in the Metro Manila, the Philippine

    NASA Astrophysics Data System (ADS)

    Deguchi, T.

    2010-12-01

    Tomonori Deguchi (Nittetsu Mining Consultants Co., Ltd.) Yoshihiro Kinugasa (Association for the Development of Earthquake Prediction) Katsumi Kurita (Tokyo Metropolitan College of Industrial Technology) Makoto Omura (Kochi Womes's University) Tomoya Oku (Earth Remote Sensing Data Analysis Center) Many ground deformations have been occurred by earthquakes and volcanic activities in the Republic of the Philippines. The monitoring of deformation using InSAR, which is capable to observe a wide area at high spatial resolution, as well as GPS measurement and leveling survey, which are capable to measure the point-based but subtle land displacement less than a centimeter, is actively conducted in this country. The Valley fault exhibits fault creep displacement. It is a north-south trending active fault on the eastern edge of the Metro Manila district, central Luzon. Some buildings and road pavement are damaged by vertical displacement of the ground where the central segment of the fault passes through. Moreover, overpumping of groundwater in the Metro Manila district has occurred huge ground subsidences. The purpose of this study is to investigate the distribution of spatial and temporal change on the earth surface around Metro Manila. We measured long-term ground deformation from 2003 until 2010 by means of InSAR and time series analysis using ENVISAT/ASAR data. As a result, it shows that the uplift phenomena in the western part of Valley fault are uniform. On the other hand, the land movement in the eastern part of the Valley fault had reversed from subsidence to uplift in around 2007. It would be difficult to conceive that these tendencies resulted from groundwater pumping. We applied DInSAR using TerraSAR-X data in order to measure the detailed spatial distribution of creep displacement around the Valley fault. Additionally, we tried to detect a steep gradient of interferometric phase using the first differentiation. From this analysis, some segments in the direction

  4. Structural Analysis of Recent and Active Faults and Regional State of Stress in the Epicentral Area of the 1978 Thessaloniki Earthquakes (northern Greece)

    NASA Astrophysics Data System (ADS)

    Mercier, Jacques-Louis; Carey-Gailhardis, Evelyne; Mouyaris, Nicolas; Simeakis, Konstantinos; Roundoyannis, Theodora; Anghelidhis, Christos

    1983-12-01

    During spring and summer 1978, Macedonia (Greece) suffered damaging seismic activity. During the two main shocks which occurred on May 23 (Mb = 5.7) and June 20 (Mb = 6.1), seismic open cracks and faults were formed in the epicentral area, 25 km NNE from Thessaloniki. They have been mapped and their kinematics analyzed. These studies have shown that they result from the reactivation of existing faults of Pleistocene, Recent, and historical age and that the crust is stretching along a N-S to NNE-SSW direction in that part of the North Aegean. Principal stress directions have been computed from the slip vectors measured on recent neotectonic faults and seismic cracks and faults, this computation utilizing a simple mechanical model (homogeneous deformation through the addition of small and independent displacements of rigid blocks in a highly fractured body). A striking feature of this analysis is that the tensional directions σ3 deduced from seismic faulting and from recent neotectonic faulting are nearly the same. They are compatible with the regional tension axis deduced from focal mechanisms of North Aegean and with the focal mechanisms of the 1978 Thessaloniki main shocks. They are also compatible with in situ stress measurements in this region. Studies of superficial seismic faulting strongly support previous assumptions proposed from aftershock distribution: the 1978 Thessaloniki earthquakes resulted from reactivation of several different faults situated within the same NE dipping fault zone of Upper Eocene-Lower Oligocene age (and older) separating the Serbo-Macedonian Massif from the Peonias (East Vardar) zone.

  5. Identifying Active Faults in Northeast North America Using Hypocenters and Multiscale Edge Wavelet Analyses of Potential Fields

    NASA Astrophysics Data System (ADS)

    Carpenter, K.; Horowitz, F.; Ebinger, C. J.; Navarrete, L. C.; Diaz-Etchevehere, D.

    2015-12-01

    Multiscale edge Poisson wavelet analyses of potential field data ("worms") have a physical interpretation as the locations of lateral boundaries in a source distribution that exactly generates the observed field. The worm technique is therefore well-suited to analyses of crustal-scale stuctures that could be reactivated by tectonic stress or by fluid injection processes, providing new tools to analyze existing continental-scale data sets. Northeastern North America (US, Canada) hosts potentially damaging intraplate earthquakes, yet many of the Proterozoic structures are covered by thick sedimentary sequences or dense vegetation, and crustal structure is relatively poorly known.For the purpose of extending basement structure beneath the Appalachian basin and establishing a consistent regional basis for comparison, we use worms to identify steeply dipping structures in compiled gravity and magnetic anomaly data sets. We compare results to intraplate earthquake locations to assess seismic hazards. Clearly, not all locations of lateral boundaries are faults, and we do not expect all faults to have shown activity in the ~50 years of seismic records available. However, proximity statistics between hypocenters and worms are of interest since they assist in the identification and location of a subset of potentially active faults. We compare structures of lateral mass-density or magnetization contrast with locations of earthquake hypocenters cataloged from the ISC, the NEIC, and the ANF from the EarthScope Transportable Array. We develop a GIS based method for calculating hypocenter/worm proximity, and we will show statistics and maps from this method for the region at the meeting.

  6. Map and Data for Quaternary Faults and Fault Systems on the Island of Hawai`i

    USGS Publications Warehouse

    Cannon, Eric C.; Burgmann, Roland; Crone, Anthony J.; Machette, Michael N.; Dart, Richard L.

    2007-01-01

    Introduction This report and digitally prepared, GIS-based map is one of a series of similar products covering individual states or regions of United States that show the locations, ages, and activity rates of major earthquake-related features such as faults and fault-related folds. It is part of a continuing the effort to compile a comprehensive Quaternary fault and fold map and database for the United States, which is supported by the U.S. Geological Survey's (USGS) Earthquake Hazards Program. Guidelines for the compilation of the Quaternary fault and fold maps for the United States were published by Haller and others (1993) at the onset of this project. This compilation of Quaternary surface faulting and folding in Hawai`i is one of several similar state and regional compilations that were planned for the United States. Reports published to date include West Texas (Collins and others, 1996), New Mexico (Machette and others, 1998), Arizona (Pearthree, 1998), Colorado (Widmann and others, 1998), Montana (Stickney and others, 2000), Idaho (Haller and others, 2005), and Washington (Lidke and others, 2003). Reports for other states such as California and Alaska are still in preparation. The primary intention of this compilation is to aid in seismic-hazard evaluations. The report contains detailed information on the location and style of faulting, the time of most recent movement, and assigns each feature to a slip-rate category (as a proxy for fault activity). It also contains the name and affiliation of the compiler, date of compilation, geographic and other paleoseismologic parameters, as well as an extensive set of references for each feature. The map (plate 1) shows faults, volcanic rift zones, and lineaments that show evidence of Quaternary surface movement related to faulting, including data on the time of most recent movement, sense of movement, slip rate, and continuity of surface expression. This compilation is presented as a digitally prepared map product

  7. Active Fault Mapping of Naga-Disang Thrust (Belt of Schuppen) for Assessing Future Earthquake Hazards in NE India

    NASA Astrophysics Data System (ADS)

    Kumar, A.

    2014-12-01

    We observe the geodynamic appraisal of Naga-Disang Thrust North East India. The Disang thrust extends NE-SW over a length of 480 km and it defines the eastern margin of Neogene basin. It branches out from Haflong-Naga thrust and in the NE at Bulbulia in the right bank of Noa Dihing River, it is terminated by Mishmi thrust, which extends into Myanmar as 'Sagaing fault,which dip generally towards SE. It extends between Dauki fault in the SW and Mishmi thrust in the NE. When the SW end of 'Belt of Schuppen' moved upwards and towards east along the Dauki fault, the NE end moved downwards and towards west along the Mishmi thrust, causing its 'S' shaped bending. The SRTM generated DEM is used to map the topographic expression of the schuppen belt, where these thrusts are significantly marked by topographic break. Satellite imagery map also shows presence lineaments supporting the post tectonic activities along Naga-Disang Thrusts. The southern part of 'Belt of Schuppen' extends along the sheared western limb of southerly plunging Kohima synform, a part of Indo Burma Ranges (IBR) and it is seismically active.The crustal velocity at SE of Schuppen is 39.90 mm/yr with a azimuth of 70.780 at Lumami, 38.84 mm/yr (Azimuth 54.09) at Senapati and 36.85 mm/yr (Azimuth 54.09) at Imphal. The crustal velocity at NW of Schuppen belt is 52.67 mm/yr (Azimuth 57.66) near Dhauki Fault in Meghalaya. It becomes 43.60 mm/yr (Azimuth76.50) - 44.25 (Azimuth 73.27) at Tiding and Kamlang Nagar around Mishmi thrust. The presence of Schuppen is marked by a change in high crustal velocity from Indian plate to low crustal velocity in Mishmi Suture as well as Indo Burma Ranges. The difference in crustal velocities results in building up of strain along the Schuppen which may trigger a large earthquake in the NE India in future. The belt of schuppean seems to be seismically active, however, the enough number of large earthquakes are not recorded. These observations are significant on Naga

  8. Profiles of volumetric water content in fault zones retrieved from hole B of the Taiwan Chelungpu-fault Drilling Project (TCDP)

    NASA Astrophysics Data System (ADS)

    Lin, Weiren; Matsubayashi, Osamu; Yeh, En-Chao; Hirono, Tetsuro; Tanikawa, Wataru; Soh, Wonn; Wang, Chien-Ying; Song, Sheng-Rong; Murayama, Masafumi

    2008-01-01

    To determine the distribution pattern of water content in the three major fault zones penetrated by the Taiwan Chelungpu-fault Drilling Project (TCDP) hole B, and to assess a rapid, nondestructive water content measurement technique, time domain reflectometry (TDR), we determined the volumetric water content of sequential core samples and found that water content increased toward the center of each of the three fault zones, except in the disk-shaped black material. We observed distinct anomalies in the water content and resistivity profiles, particularly in the shallowest major fault zone (FZB1136), supporting the hypothesis that FZB1136 ruptured during the 1999 Chi-Chi earthquake. This study, the first successful application of the TDR technique to determine water content of core samples, including fault zone samples, collected by an active-fault drilling project, showed that this technique is suitable for measuring water content of fault core samples.

  9. Review of magnetic and electric field effects near active faults and volcanoes in the U.S.A.

    USGS Publications Warehouse

    Johnston, M.J.S.

    1989-01-01

    Synchronized measurements of geomagnetic field have been recorded along 800 km of the San Andreas fault and in the Long Valley caldera since 1974, and during eruptions on Mount St. Helens since 1980. For shorter periods of time, continuous measurements of geoelectric field measurements have been made on Mount St. Helens and near the San Andreas fault where moderate seismicity and fault slip frequently occurs. Significant tectonic and volcanic events for which nearby magnetic and electric field data have been obtained include: (1) two moderate earthquakes (ML > 5.8) for which magnetometers were close enough to expect observable signals (about three source lengths), (2) one moderate earthquake (MS 7.3) for which magnetometers were installed as massive fluid outflow occurred during the post-seismic phase, (3) numerous fault creep events and moderate seismicity, (4) a major explosive volcanic eruption and numerous minor extrusive eruptions, and (5) an episode of aseismic uplift. For one of the two earthquakes with ML > 5.8, seismomagnetic effects of -1.3 and -0.3 nT were observed. For this event, magnetometers were optimally located near the epicenter and the observations obtained are consistent with simple seismomagnetic models of the event. Similar models for the other event indicate that the expected seismomagnetic effects are below the signal resolution of the nearest magnetometer. Precursive tectonomagnetic effects were recorded on two independent instruments at distances of 30 and 50 km from a ML 5.2 earthquake. Longer-term changes were recorded in one region in southern California where a moderate ML 5.9 earthquake has since occurred. Surface observations of fault creep events have no associated magnetic or electrical signature above the present measurement precision (0.25 nT and 0.01%, respectively) and are consistent with near-surface fault failure models of these events. Longer-term creep is sometimes associated with corresponding longer-term magnetic field

  10. Tectonic activity as a significant source of crustal tetrafluoromethane emissions to the atmosphere: Observations in groundwaters along the San Andreas Fault

    NASA Astrophysics Data System (ADS)

    Deeds, Daniel A.; Kulongoski, Justin T.; Mühle, Jens; Weiss, Ray F.

    2015-02-01

    Tetrafluoromethane (CF4) concentrations were measured in 14 groundwater samples from the Cuyama Valley, Mil Potrero and Cuddy Valley aquifers along the Big Bend section of the San Andreas Fault System (SAFS) in California to assess whether tectonic activity in this region is a significant source of crustal CF4 to the atmosphere. Dissolved CF4 concentrations in all groundwater samples but one were elevated with respect to estimated recharge concentrations including entrainment of excess air during recharge (Cre; ∼30 fmol kg-1 H2O), indicating subsurface addition of CF4 to these groundwaters. Groundwaters in the Cuyama Valley contain small CF4 excesses (0.1-9 times Cre), which may be attributed to an in situ release from weathering and a minor addition of deep crustal CF4 introduced to the shallow groundwater through nearby faults. CF4 excesses in groundwaters within 200 m of the SAFS are larger (10-980 times Cre) and indicate the presence of a deep crustal flux of CF4 that is likely associated with the physical alteration of silicate minerals in the shear zone of the SAFS. Extrapolating CF4 flux rates observed in this study to the full extent of the SAFS (1300 km × 20-100 km) suggests that the SAFS potentially emits (0.3- 1) ×10-1 kg CF4 yr-1 to the Earth's surface. For comparison, the chemical weathering of ∼ 7.5 ×104km2 of granitic rock in California is estimated to release (0.019- 3.2) ×10-1 kg CF4 yr-1. Tectonic activity is likely an important, and potentially the dominant, driver of natural emissions of CF4 to the atmosphere. Variations in preindustrial atmospheric CF4 as observed in paleo-archives such as ice cores may therefore represent changes in both continental weathering and tectonic activity, including changes driven by variations in continental ice cover during glacial-interglacial transitions.

  11. Abundant off-fault seismicity and orthogonal structures in the San Jacinto fault zone

    PubMed Central

    Ross, Zachary E.; Hauksson, Egill; Ben-Zion, Yehuda

    2017-01-01

    The trifurcation area of the San Jacinto fault zone has produced more than 10% of all earthquakes in southern California since 2000, including the June 2016 Mw (moment magnitude) 5.2 Borrego Springs earthquake. In this area, the fault splits into three subparallel strands and is associated with broad VP/VS anomalies. We synthesize spatiotemporal properties of historical background seismicity and aftershocks of the June 2016 event. A template matching technique is used to detect and locate more than 23,000 aftershocks, which illuminate highly complex active fault structures in conjunction with a high-resolution regional catalog. The hypocenters form dipping seismicity lineations both along strike and nearly orthogonal to the main fault, and are composed of interlaced strike-slip and normal faults. The primary faults change dip with depth and become listric by transitioning to a dip of ~70° near a depth of 10 km. The Mw 5.2 Borrego Springs earthquake and past events with M > 4.0 occurred on the main faults, whereas most of the low-magnitude events are located in a damage zone (several kilometers wide) at seismogenic depths. The lack of significant low-magnitude seismicity on the main fault traces suggests that they do not creep. The very high rate of aftershocks likely reflects the large geometrical fault complexity and perhaps a relatively high stress due to a significant length of time elapsed since the last major event. The results provide important insights into the physics of faulting near the brittle-ductile transition. PMID:28345036

  12. Abundant off-fault seismicity and orthogonal structures in the San Jacinto fault zone.

    PubMed

    Ross, Zachary E; Hauksson, Egill; Ben-Zion, Yehuda

    2017-03-01

    The trifurcation area of the San Jacinto fault zone has produced more than 10% of all earthquakes in southern California since 2000, including the June 2016 Mw (moment magnitude) 5.2 Borrego Springs earthquake. In this area, the fault splits into three subparallel strands and is associated with broad VP /VS anomalies. We synthesize spatiotemporal properties of historical background seismicity and aftershocks of the June 2016 event. A template matching technique is used to detect and locate more than 23,000 aftershocks, which illuminate highly complex active fault structures in conjunction with a high-resolution regional catalog. The hypocenters form dipping seismicity lineations both along strike and nearly orthogonal to the main fault, and are composed of interlaced strike-slip and normal faults. The primary faults change dip with depth and become listric by transitioning to a dip of ~70° near a depth of 10 km. The Mw 5.2 Borrego Springs earthquake and past events with M > 4.0 occurred on the main faults, whereas most of the low-magnitude events are located in a damage zone (several kilometers wide) at seismogenic depths. The lack of significant low-magnitude seismicity on the main fault traces suggests that they do not creep. The very high rate of aftershocks likely reflects the large geometrical fault complexity and perhaps a relatively high stress due to a significant length of time elapsed since the last major event. The results provide important insights into the physics of faulting near the brittle-ductile transition.

  13. Quaternary sedimentation and active faulting along the Ecuadorian shelf: preliminary results of the ATACAMES Cruise (2012)

    NASA Astrophysics Data System (ADS)

    Michaud, F.; Proust, J. N.; Collot, J. Y.; Lebrun, J. F.; Witt, C.; Ratzov, G.; Pouderoux, H.; Martillo, C.; Hernández, M. J.; Loayza, G.; Penafiel, L.; Schenini, L.; Dano, A.; Gonzalez, M.; Barba, D.; De Min, L.; Ponce, G.; Urresta, A.; Calderon, M.

    2015-03-01

    Selected high-resolution seismic-reflection profiles and multibeam bathymetry acquired along the convergent Ecuador margin during the ATACAMES cruise on onboard the R/V L'Atalante (Jan.15-Feb.18, 2012) allow a preliminary evaluation of the neotectonic development and stratigraphic evolution of the margin based on the sismo-stratigraphic analysis of Quaternary sediment preserved on the margin shelf and upper slope. We present three major preliminary results. (1) The evolution of the Esmeraldas, Guayaquil and Santa Elena canyons. The head of the Esmeraldas canyon is the location of a continuous significant sediment transport. The Guayaquil canyon shows several episodes of deposition and incision. Aggrading sedimentation pattern in the canyon records several changes in relative sea-level. The subsidence of the Gulf of Guayaquil probably contributes to the good preservation of the canyon filling stages. The Santa Elena canyon is controlled by a SW-NE trending normal fault. (2) Variations of sediment accumulation and relative vertical motions are shown along-strike the shelf edge. Offshore the uplifted Manta peninsula, a pronounced subsidence of the shelf edge is documented by sedimentary clinoforms that have deposited in a morphological reentrant, and have migrated upslope testifying of a local subsidence meanwhile the adjacent La Plata Island area underwent uplift. In the Esmeraldas canyon area, a local uplift of the shelf is documented. (3) Two neotectonic fault systems with a possible transcurrent component are imaged across the shelf edge and upper margin slope offshore Jama, and Cape Galera. This possible transcurrent motion could be related to the reactivation of ancient faults of the upper plate by the subduction. These preliminary results indicate that the ATACAMES data set has a strong potential to evaluate the spatial and temporal contribution of tectonic and climate changes on the structural development and stratigraphic evolution of the Ecuador continental

  14. Recent deformation along the offshore Malibu Coast, Dume, and related faults west of Point Dume, southern California

    USGS Publications Warehouse

    Fisher, M.A.; Langenheim, V.E.; Sorlien, C.C.; Dartnell, P.; Sliter, R.W.; Cochrane, G.R.; Wong, F.L.

    2005-01-01

    Offshore faults west of Point Dume, southern California, are part of an important regional fault system that extends for about 206 km, from near the city of Los Angeles westward along the south flank of the Santa Monica Mountains and through the northern Channel Islands. This boundary fault system separates the western Transverse Ranges, on the north, from the California Continental Borderland, on the south. Previous research showed that the fault system includes many active fault strands; consequently, the entire system is considered a serious potential earthquake hazard to nearby Los Angeles. We present an integrated analysis of multichannel seismic- and high-resolution seismic-reflection data and multibeam-bathymetric information to focus on the central part of the fault system that lies west of Point Dume. We show that some of the main offshore faults have cumulative displacements of 3-5 km, and many faults are currently active because they deform the seafloor or very shallow sediment layers. The main offshore fault is the Dume fault, a large north-dipping reverse fault. In the eastern part of the study area, this fault offsets the seafloor, showing Holocene displacement. Onshore, the Malibu Coast fault dips steeply north, is active, and shows left-oblique slip. The probable offshore extension of this fault is a large fault that dips steeply in its upper part but flattens at depth. High-resolution seismic data show that this fault deforms shallow sediment making up the Hueneme fan complex, indicating Holocene activity. A structure near Sycamore knoll strikes transversely to the main faults and could be important to the analysis of the regional earthquake hazard because the structure might form a boundary between earthquake-rupture segments.

  15. Were Holocene large slumps in Lake Geneva off the city of Lausanne caused by fault activity?

    NASA Astrophysics Data System (ADS)

    Correia Demand, Jehanne; Marillier, François; Kremer, Katrina; Girardclos, Stéphanie

    2014-05-01

    Lake Geneva is set in an area where glacier advances and retreats have carved Tertiary Molasse rocks in front of the Alpine units. Glacial and lacustrine sediments have accumulated in the lake on top of the Molasse. Within Holocene sedimentary layers, seismic studies in the central part of Lake Geneva ("Grand-Lac") have shown the presence of several mass transport deposits (MTD). A large one, MTD A, is observed off the city of Lausanne. The depth of the associated failure scars (100 m water depth), its volume (~ 0.13 km3), and the occurrence of other smaller MTDs that were possibly co-deposited with MTD A point to the occurrence of a major slide event in the lake, most likely associated with an earthquake. Based on 14C dating, the sediment age model for MTD A gives an age interval of 1865-1608 BC (Kremer et al. 2014). To resolve the details of the MTDs off Lausanne, and to better understand its geological context different seismic systems were used. These were a 3.5 KHz pinger with a theoretical vertical resolution of 0.15 m and a multichannel system with water-gun or air-gun seismic sources with vertical resolution of 0.6 m and 1.1 m, respectively. After a first pass processing, the multi-channel data were reprocessed in order to take into account the shape of the streamer in the water and to enhance the results of migration. In addition to typical seismic images of MTDs observed in other alpine lakes such as chaotic or transparent seismic character between well-organized reflections, two intriguing positive water-bottom topographic features associated with apparent sub-vertical offsets are revealed by the seismic data. They are located in the near vicinity of the depot centers of the MTDs and conspicuously located near faults in the Tertiary Molasse. These are thrust faults that are offset by small strike-slip faults, and we suggest that the positive topographic features are linked to a compressive component within the sediments due to displacements along these

  16. Multi-component Magnetization Of The Late Pliocene Pyroclastic Flow Deposit In Central Japan, Indicating Early Early Pleistocene Fault Activity

    NASA Astrophysics Data System (ADS)

    Ueki, T.; Yamazaki, T.; Funaki, M.; Hoshi, H.

    2003-12-01

    The Late Pliocene Ichiuda Welded Tuff Bed in central Japan acquired three magnetization components. All of primary reverse intermediate temperature component, and secondary normal low and high temperature components show positive fold tests, indicating that fault-related folding structure postdated the Olduvai normal subchron. The northern segment of Itoigawa-Shizuoka Tectonic Line that bounds the North American and Eurasian Plates in central Japan, comprises the geological Otari-Nakayama and active Kamishiro faults. The Ichiuda Welded Tuff Bed intruded by the 2.1 Ma Taro-yama Andesite is subjected to the NE-SW trending folding structure adjacent to the Otari-Nakayama fault. PAFD and PThD were performed to the drilled samples of Taro-yama Andesi