Kenneth W. Hudnut

• Ph.D., Columbia Univ. (1989)
• Seismic Expert at Southern California Edison

Surface rupture from the 2019 Ridgecrest earthquake sequence, initially associated with the Mw 6.4 foreshock, occurred on 4 July on a ∼17 km long, northeast–southwest-oriented, left-lateral zone of faulting. Following the Mw 7.1 mainshock on 5 July (local time), extensive northwest–southeast-oriented, right-lateral faulting was then also mapped alo...

The Ridgecrest Earthquake sequence included a foreshock event on July 4 2019 (M6.4) and a M7.1 mainshock event on July 5 2019. These events occurred in the Eastern California Shear Zone, near Indian Wells Valley, south of China Lake and west of Searles Valley. GEER has partnered with several organizations to collect perishable data and document the...

The moment magnitude 7.2 El Mayor−Cucapah (EMC) earthquake of 2010 in northern Baja California, Mexico produced a cascading rupture that propagated through a geometrically diverse network of intersecting faults. These faults have been exhumed from depths of 6−10 km since the late Miocene based on low-temperature thermochronology, synkinematic alter...

The Mw 6.4 and Mw 7.1 Ridgecrest earthquake sequence occurred on 4 and 5 July 2019 within the eastern California shear zone of southern California. Both events produced extensive surface faulting and ground deformation within Indian Wells Valley and Searles Valley. In the weeks following the earthquakes, more than six dozen scientists from governme...

The 2019 Ridgecrest earthquake sequence produced a 4 July M 6.5 foreshock and a 5 July M 7.1 mainshock, along with 23 events with magnitudes greater than 4.5 in the 24 hr period following the mainshock. The epicenters of the two principal events were located in the Indian Wells Valley, northwest of Searles Valley near the towns of Ridgecrest, Trona...

Surface rupture in the 2019 Ridgecrest, California, earthquake sequence occurred along two orthogonal cross faults and includes dominantly left-lateral and northeast-striking rupture in the Mw 6.4 foreshock and dominantly right-lateral and northwest-striking rupture in the Mw 7.1 mainshock. We present >650 field-based, surface-displacement observat...

The 2019 Ridgecrest, California, earthquake sequence produced observable crustal deformation over much of central and southern California, as well as surface rupture over several tens of kilometers. To obtain a detailed picture of the fault slip involved in the 4 July M 6.4 foreshock and 6 July M 7.1 mainshock, we combine strong-motion seismic wave...

The U.S. Geological Survey’s geodetic response to the 4–5 July 2019 (Pacific time) Ridgecrest earthquake sequence comprised primarily the installation and/or reoccupation of Global Navigation Satellite System (GNSS) monumentation. Our response focused primarily on the United States’ Navy’s China Lake Naval Air Weapons Station base (NAWSCL). This fo...

The 2019 Ridgecrest, California, earthquake sequence, including an Mw 6.4 event on 4 July and an Mw 7.1 approximately 34 hr later, was recorded by 15 instruments within 55 km nearest-fault distance. To characterize and explore near-field ground motions from the Mw 6.4 foreshock and Mw 7.1 mainshock, we augment these records with available macroseis...

Earthquake-related fault slip in the upper hundreds of meters of Earth’s surface has remained largely unstudied because of challenges measuring deformation in the near field of a fault rupture. We analyze centimeter-scale accuracy mobile laser scanning (MLS) data of deformed vine rows within ±300 m of the principal surface expression of the M (magn...

Toppling analysis of a precariously balanced rock (PBR) can provide insight into the nature of ground motion that has not occurred at that location in the past and, by extension, can constrain peak ground motions for use in engineering design. Earlier approaches have targeted 2D models of the rock or modeled the rock–pedestal contact using spring‐d...

The Sacramento–San Joaquin Delta is a vital resource for the state of California, providing fresh water to approximately one million cultivated hectares and more than two thirds of the state population. This freshwater resource is protected by several inner islands in the delta and a system of levees that extends 1,700 kilometers and prevents salt...

The Mw 6.0 South Napa earthquake of 24 August 2014 caused slip on several active fault strands within the West Napa Fault Zone (WNFZ). Field mapping identified 12.5 km of surface rupture. These field observations, near-field geodesy and space geodesy together provide evidence for more than ~30 km of surface deformation with a relatively complex dis...

Remote sensing via LiDAR (Light Detection And Ranging) has proven extremely useful in both Earth science and hazard related studies. Surveys taken before and after an earthquake for example, can provide decimeter-level, 3D near-field estimates of land deformation that offer better spatial coverage of the near field rupture zone than other geodetic...

Remote sensing via LiDAR (Light Detection And Ranging) has proven extremely useful in both Earth science and hazard related studies. Surveys taken before and after an earthquake for example, can provide decimeter-level, 3D near-field estimates of land deformation that offer better spatial coverage of the near field rupture zone than other geodetic...

Nepal's quake-driven landslide hazards Large earthquakes can trigger dangerous landslides across a wide geographic region. The 2015 M w 7.8 Gorhka earthquake near Kathmandu, Nepal, was no exception. Kargal et al. used remote observations to compile a massive catalog of triggered debris flows. The satellite-based observations came from a rapid respo...

The Gorkha earthquake (M 7.8) on 25 April 2015 and later aftershocks struck South Asia, killing ~9,000 and damaging a large region. Supported by a large campaign of responsive satellite data acquisitions over the earthquake disaster zone, our team undertook a satellite image survey of the earthquakes’ induced geohazards in Nepal and China and an as...

The 25 April 2015 Mw 7.8 Gorkha earthquake caused more than 8000 fatalities and widespread building damage in central Nepal. The Italian Space Agency's COSMO-SkyMed Synthetic Aperture Radar (SAR) satellite acquired data over Kathmandu area four days after the earthquake and the Japan Aerospace Exploration Agency's Advanced Land Observing Satellite-...

Detailed geodetic imaging of earthquake ruptures enhances our understanding of earthquake physics and associated ground shaking. The 25 April 2015 moment magnitude 7.8 earthquake in Gorkha, Nepal was the first large continental megathrust rupture to have occurred beneath a high-rate (5-hertz) Global Positioning System (GPS) network. We used GPS and...

Detailed geodetic imaging of earthquake rupture enhances our understanding of earthquake physics and induced ground shaking. The April 25, 2015 Mw 7.8 Gorkha, Nepal earthquake is the first example of a large continental megathrust rupture beneath a high-rate (5 Hz) GPS network. We use GPS and InSAR data to model the earthquake rupture as a slip pul...

The Nepal Geodetic Array was funded by internal funding to JPA from Caltech and DASE and by the Gordon and Betty Moore Foundation, through Grant GBMF 423.01 to the Caltech Tectonics Observatory and was maintained thanks to NSF Grant EAR 13-5136. Andrew Miner and the PAcific Northwest Geodetic Array (PANGA) at Central Washington University are than...

It has long been known that fluid injection or withdrawal can induce earthquakes, but the underlying mechanisms remain elusive. For example, the 2012 Brawley swarm, which produced two strike-slip shocks with magnitudes larger than 5.3 and surface ruptures in the close vicinity of a geothermal field, started with earthquakes about 5 km deeper than t...

We systematically mapped (scales >1:500) the surface rupture of the 4 April 2010 Mw (moment magnitude) 7.2 El Mayor-Cucapah earthquake through the Sierra Cucapah (Baja California, northwestern Mexico) to understand how faults with similar structural and lithologic characteristics control rupture zone fabric, which is here defined by the thickness,...

The 16 October 1999 Hector Mine earthquake (Mw 7.1) was the first large earthquake for which postearthquake airborne Light Detection and Ranging (LiDAR) data were collected to image the fault surface rupture. In this work, we present measurements of both vertical and horizontal slip along the entire surface rupture of this earthquake based on airbo...

The Mw 6.0 South Napa earthquake, which occurred at 10:20 UTC 24 August 2014 was the largest earthquake to strike the greater San Francisco Bay area since the Mw 6.9 1989 Loma Prieta earthquake. The rupture from this right‐lateral earthquake propagated mostly unilaterally to the north and up‐dip, directing the strongest shaking toward the city of N...

In summary, our analysis of the Mw 6.1 South Napa earthquake indicates the rupture occurred on two near-vertical fault segments, each dipping about 82° to the northeast. The northeast dip of the southernmost fault segment is consistent with our relocation of the mainshock epicenter and the mapped surface rupture, although our inversion cannot rule...

A magnitude 6.0 earthquake struck southern Napa county northeast of San Francisco, California, on Aug. 24, 2014, causing significant damage in the city of Napa and nearby areas. One day after the earthquake, the Advanced Rapid Imaging and Analysis (ARIA) team produced and released observations of coseismic ground displacement measured with continuo...

Executive Summary. Through discussions between the Federal Emergency Management Agency (FEMA) and the U.S. Geological Survey (USGS) following the South Napa earthquake, it was determined that several key decision points would be faced by FEMA for which additional information should be sought and provided by USGS and its partners. This report addres...

On August 24, 2014 10:20:44 (UTC), a magnitude Mw 6.0 earthquake occurred on the West Napa Fault zone, a system of faults striking NNW from American Canyon and along the western edge of Napa Valley in Northern California. The epicenter was located at N 38.220 W 122.313, approximately 8 km SSW of Napa, California, 14 km ESE of Sonoma, California, an...

We systematically mapped (scales >1:500) the surface rupture of the 4 April 2010 Mw 7.2 El Mayor-Cucapah earthquake through Sierra Cucapah to understand how faults with similar structural and lithologic characteristics control rupture zone fabric, which is here defined by the thickness, distribution and internal configuration of shearing in a ruptu...

The 4 April 2010 moment magnitude (M_w) 7.2 El Mayor–Cucapah earthquake revealed the existence of a previously unidentified fault system in Mexico that extends ∼120 km from the northern tip of the Gulf of California to the U.S.–Mexico border. The system strikes northwest and is composed of at least seven major faults linked by numerous smaller faul...

High-precision and high-resolution topography are the fundamental data for active fault research. Light detection and ranging (LiDAR) presents a new approach to build detailed digital elevation models effectively. We take the Haiyuan fault in Gansu Province as an example of how LiDAR data may be used to improve the study of active faults and the ri...

Lidar (light detection and ranging), a method by which the precise time of flight of emitted pulses of laser energy is measured and converted to distance for reflective targets, has helped scientists make topographic maps of Earth's surface at scales as fine as centimeters. These maps have allowed the discovery and analysis of myriad otherwise unst...

New field observations, aerial surveys, LiDAR measurements and laboratory studies of mud samples (2006 to 2012) are reported of several formerly submerged fumarole complexes that are presently undergoing surface exposure as the Salton Sea level drops. Some remain submerged as of this writing (2012). The fumarole fields range in area from 1000 to ~...

We investigate the finite rupture processes of two M > 5 earthquakes in the 2012 Brawley swarm by joint inversion of nearby strong motion and high-rate GPS data. Waveform inversions up to 3 Hz were made possible by using a small event (Mw3.9) for path calibration of the velocity structure. Our results indicate that the first (Mw5.3) event ruptured...

The 2012 Brawley earthquake swarm occurred in the Brawley Seismic Zone (BSZ) within the Imperial Valley of southern California (Fig. 1). The BSZ is the northernmost extensional segment of the Pacific–North America plate boundary system. Johnson and Hill (1982) used the distribution of seismicity since the 1930s to outline the geographical extent of...

We describe a prototype compact mobile laser scanning system that may be operated from a backpack or unmanned aerial vehicle. The system is small, self-contained, relatively inexpensive, and easy to deploy. A description of system components is presented, along with the initial calibration of the multi- sensor platform. The first field tests of the...

The 2011 Mw 9.1 Tohoku-Oki earthquake had unusually large slip (over 50 m) concentrated in a relatively small region, with local stress drop inferred to be 5–10 times larger than that found for typical megathrust earthquakes. Here we conduct a detailed analysis of foreshocks and aftershocks (Mw 5.5–7.5) sampling this megathrust zone for possible cl...

The ~ 220 km-long rupture of the 2008 Mw 7.9 Wenchuan earthquake breached several km-scale geometric discontinuities along strike, including the previously un-mapped NW-trending Xiaoyudong fault, connecting between the two major, NE-trending rupture planes on the Beichuan and Pengguan Faults. In this paper, we present high-resolution mapping of the...

We measured offsets on tectonically displaced geomorphic features along 80 km of the Clark strand of the San Jacinto fault (SJF) to estimate slip-per-event for the past several surface ruptures. We identify 168 offset features from which we make over 490 measurements using B4 light detection and ranging (LiDAR) imagery and field observations. Our r...

Large [moment magnitude (Mw) ≥ 7] continental earthquakes often generate complex, multifault ruptures linked by enigmatic zones of distributed deformation. Here, we report the collection and results of a high-resolution (≥nine returns per square meter) airborne light detection and ranging (LIDAR) topographic survey of the 2010 Mw 7.2 El Mayor–Cucap...

The Mw 7.2 El Mayor-Cucapah earthquake revealed the existence of a previously unidentified plate-margin fault system that extends 120 km from the northern tip of the Gulf of California to the international border. The system is composed of at least 6 major faults linked by numerous smaller faults. We observed that localized kinematics on individual...

The American Recovery and Reinvestment Act of 2009 (ARRA) provided money to the U.S. Geological Survey (USGS) for many projects, including improvements to earthquake and volcano monitoring. The USGS Earthquake Hazards Program's geodetic projects include station upgrades, new equipment and software tools, and improvements to geodetic infrastructure....

Over the past several years, USGS has developed the infrastructure for integrating real-time GPS with seismic data in order to improve our ability to respond to earthquakes and volcanic activity. As part of this effort, we have tested real-time GPS processing software components , and identified the most robust and scalable options. Simultaneously,...

The 2010 El Mayor-Cucapah earthquake has produced some unique observations that exemplify the complexity of rupture dynamics. An eyewitness located near the fault when the rupture broke reported signatures of reverse surface rupture (rupture towards the South at a location North from the hypocenter). We report here on seismological evidence of this...

The 2011 Mw 9.0 Tohoku-Oki earthquake occurred with unusually large slip (over 50 m) concentrated in a relatively small region with the inferred local stress drop 5-10 times larger than found for typical megathrust earthquakes. By applying a new high-resolution seismic waveform analysis approach, we determine that smaller earthquakes occurring in t...

New field observations, lidar measurements, aerial imaging and preliminary laboratory measurements of mud samples are reported of three formerly submerged fumarole fields in the Salton Trough near Mullet Island in southeastern California, USA. The fumarole fields have recently been exposed as the Salton Sea level has dropped. The largest of the thr...

The 16 October 1999 Hector Mine earthquake (Mw7.1) generated significant surface rupture along the Lavic Lake Fault through almost 60 kilometers of sparsely vegetated, relatively barren desert terrain. It was the first large earthquake for which post-earthquake airborne LiDAR, collected to image the fault surface rupture, exists. Despite the lack o...

One-hundred and three years after the publication of the Lawson report on the Great 1906 earthquake, accurate documentation of surface deformation along the entire length of an earthquake is still challenging. Analysis of pre- and post-earthquake topographic data provides an opportunity to deliver the full 3D displacement field of the ground's surf...

Recent major disasters have resulted from diverse earthquakes and related phenomena, hence a daunting array of observational challenges was encountered in the past few years. Rapid characterization of damage to provide situational awareness, and to inform disaster management decisions, has repeatedly proven important after recent events. The 2004 M...

The geometry of faults is usually thought to be more complicated at the surface than at depth and to control the initiation, propagation and arrest of seismic ruptures. The fault system that runs from southern California into Mexico is a simple strike-slip boundary: the west side of California and Mexico moves northwards with respect to the east. H...

An earthquake planning scenario document was recently released by the USGS and California Geological Survey that hypothesizes the occurrence and effects of a MW7.8 earthquake on the southern San Andreas Fault. It was created by more than 300 scientists and engineers. Fault offsets reach 13m, and up to 8m at lifeline crossings. Physics-based modelin...

The ShakeOut Scenario is premised upon the detailed description of a hypothetical M w 7.8 earthquake on the southern San Andreas Fault and the associated simulated ground motions. The main features of the scenario, such as its endpoints, magnitude, and gross slip distribution, were defined through expert opinion and incorporated information from ma...

The new GPS L1C (Global Positioning System New Civilian) signal, due to be launched in 2014, enhances PNT (Positioning, Navigation, and Timing) performance as well as interoperability with other GNSS signals. It is a composite of two signals that are phase/frequency coherent with synchronized spreading codes and symbol timing. Subframe 3 of the L1C...

Field observations provide strong evidence for four intriguing aspects of rupture process complexity for the 4 April 2010 El Mayor - Cucapah - Indiviso earthquake. First, the southern ``fork'' of the rupture exhibits two splays just to the northwest of the event epicenter, both with nearly pure right-lateral faulting. Teleseismic source modeling by...

We have investigated the kinematic rupture process of the 2008 Mw 7.9 Wenchuan earthquake with all the available geophysical and geological datasets. Teleseismic broadband body waves, long period surface waves, local strong motions, GPS vectors and interferometic radar (InSAR) images have been combined to constrain the spatial and temporal slip dis...

We report results from two low-cost, low-altitude, aerial imaging surveys of the San Andreas Fault (SAF) carried out in late 2009. In total 541 km of the fault was imaged with a ground sample distance (pixel size) of a few cm. The two surveys covered the Carrizo Plain and points north to the Choice Valley on 24 Sep 2009, and the SAF between I-5 (Te...

We mapped the tectonic geomorphology of 80 km of the Clark strand of the San Jacinto fault to determine slip per event for the past several surface ruptures. From the southeastern end of Clark Valley (east of Borrego Springs) northwest to the mouth of Blackburn Canyon (near Hemet), we identify 203 offset geomorphic features from which we make over...

Kinematic analysis of surface ruptures and seismicity of April 4, 2010 Mayor-Cucapah earthquake series clearly demonstrates that a broad spectrum of kinematically independent faults ruptured together to accommodate 3D strain in a single earthquake cycle. Kinematic relationships are best observed along the entire length (55 km) of the Sierra Cucapah...

We use interferometric analysis of synthetic aperture radar (SAR) images (InSAR) and pixel tracking by subpixel correlation of SAR and optical images to map the fault ruptures and surface deformation of the 4 April 2010 El Mayor-Cucapah earthquake (Mw 7.2) in Baja California, Mexico. We then combine sampled InSAR and subpixel correlation results wi...

The Mw 7.0, 12 January 2010 Léogâne, Haiti earthquake initially appeared to be a straightforward accommodation of oblique relative motion between the Caribbean and North America plates along the previously recognized Enriquillo-Plantain Garden fault zone (EPGF). Our combined geologic field observations, space geodetic measurements, and seismologic...

The catastrophic M 7.0 Léogâne earthquake of 12 January 2010 in Haiti highlighted the hazard associated with the Caribbean-North American plate boundary in Hispaniola. Although the location of the epicenter and preliminary seismologic data suggested the earthquake was likely due to slip on the Enriquillo-Plantain Garden Fault zone (EPGFZ), more det...

We investigate the slip history of the 2010 Mw 7.3 El Mayor-Cucapah earthquake by jointly inverting near-field strong motion records and teleseismic broadband waves, along with GPS static observations and high rate GPS waveforms. We use a local velocity model, averaged from Hauksson's 3D Southern California model, to approximate the earth structure...

The significant earthquakes of 2010 produced surficial expressions ranging from blind faulting and coastal uplift in Leogane, Haiti and Maule, Chile to surface faulting in Baja California, Mexico and Yushu, China. In Haiti and Baja California geodetic imaging methods strongly guided field reconnaissance and surface rupture mapping efforts, yet in q...

The April 4th, 2010 Mw 7.2 earthquake was the largest earthquake in over 100 years of known historical seismicity in the Salton Trough region. It was a relatively benign earthquake, with only two deaths related to its occurrence. It produced, however, profound agricultural and ecological changes at the southern section of the Mexicali Valley, where...

Initially, the devastating M_w 7.0, 12 January 2010 Haiti earthquake seemed to involve straightforward accommodation of oblique relative motion between the Caribbean and North American plates along the Enriquillo–Plantain Garden fault zone. Here, we combine seismological observations, geologic field data and space geodetic measurements to show that...

The October 3, 2009 (01:16:00 UTC), Olancha M5.2 earthquake caused extensive liquefaction as well as permanent horizontal ground deformation within a 1.2 km2 area earthquake in Owens Valley in eastern California (USA). Such liquefaction is rarely observed during earthquakes of M ≤ 5.2. We conclude that subsurface conditions, not unusual ground moti...

The Enriquillo-Plantain Garden fault zone is recognized as one of the primary plate-bounding fault systems in Haiti. The strike-slip fault runs adjacent to the city of Port-au-Prince and was initially thought to be the source of the 12 January 2010, Mw7.0 earthquake. Haiti experienced significant earthquakes in 1751 and 1770 (refs 3, 4, 5), but the...

This study focuses on uncertainties in estimates of the geologic slip rate along the Mission Creek strand of the southern San Andreas fault where it offsets an alluvial fan (T2) at Biskra Palms Oasis in southern California. We provide new estimates of the amount of fault offset of the T2 fan based on trench excavations and new cosmogenic 10Be age d...

U-series dating of pedogenic carbonate-clast coatings provides a reliable, precise minimum age of 45.1 ± 0.6 ka (2σ) for the T2 geomorphic surface of the Biskra Palms alluvial fan, Coachella Valley, California. Concordant ages for multiple subsamples from individual carbonate coatings provide evidence that the 238U-234U-230Th system has remained cl...

Surface rupture associated with the April 4, 2010 El Mayor-Borrego earthquake extends ~100 km from the northern tip of the Gulf of California to the international border and comprises two distinct geomorphologic and structural domains. The rupture is complex, with breaks along multiple fault strands, including minor re-rupture of the scarps associa...

We performed two quick-turnaround, low-cost color digital aerial surveys of the southern San Andreas fault and quickly placed the jpeg imagery on the Internet in the public domain. Total cost was US$3,702, excluding the cost of the camera equipment. The 5,216 geolocatable pictures (~6 Mb each covering 243 km of the fault with a GSD of a few centime...

The M 7.8 ShakeOut Scenario earthquake would result in thousands of physical injuries both directly from the ground motion and the resulting damage as well as from secondary hazards [e.g., fire-following-earthquake] . . . Overall, the earthquake is expected to result in almost 50,000 injuries requiring treatment, 750 injuries requiring specialized...

L1C, the new GPS L1 civil signal, is novel in important ways that significantly enhance PNT performance as well as interoperability with other GNSS signals. It will be broadcast by the GPS III block of satellites, with first launches as early as 2014 or 2015. Some of the novel features include: 75% of the signal power in the dataless pilot componen...

We study the kinematic rupture process of the 2008 Mw 7.9 Wenchuan earthquake using all geophysical and geological datasets that we are able to access, including the waveforms of teleseismic long period surface waves, broadband body waves and local strong motions, GPS vectors, interferometic radar (INSAR) images, and geological surface offsets. The...

UNAVCO is significantly increasing Terrestrial Laser Scanning (TLS), a.k.a. ground based LiDAR, resources available to support Earth science investigators. This increased support includes an expanded pool of available instruments, data processing facilities, and training opportunities. The planned procurement of five new TLS instruments through NSF...

We investigate a previously undocumented Precariously Balanced Rock (PBR) located above Echo Cliffs in the western Santa Monica Mountains, using Terrestrial Laser Scanning (TLS). We present the merged and aligned point cloud of TLS data (over 42 million points) and photos to document the Echo Cliffs PBR site. We also present our interpretations of...

Recent advances in hardware, telemetry, and processing software make possible real-time geodetic monitoring, including monitoring of fault-crossing lifelines, increased integration of geodetic and seismic networks, and improved geodetic response to large earthquakes. USGS Pasadena operates 97 permanent continuously operating GPS stations in souther...

The USGS Earthquake and Volcano Hazards Science Centers are developing a high-rate (1-s epoch), real-time ground deformation monitoring system using data streamed from continuously recording GPS stations. We began by evaluating the ability of GPS data reduction software to recover offsets in a displacement test data set generated by offsetting a GP...

The GREAT Alert is a NASA-sponsored, real-time prototype system designed to enhance natural hazard warning capability and damage assessment. The system takes advantage of the increasingly available global and regional real-time GPS data, as well as advanced fault and ocean dynamics models to enable more accurate and timely assessment of the magnitu...

The Ms 8.0, Wenchuan earthquake, which devastated the mountainous western rim of the Sichuan basin in central China, produced a surface rupture over 200 km-long with oblique thrust/dextral slip and maximum scarp heights of ~10 m. It thus ranks as one of the world's largest continental mega-thrust events in the last 150 yrs. Field investigation show...

Earthquake science is being communicated to and used by the 22 million residents of southern California to improve resiliency to future earthquakes through the Great Southern California ShakeOut. The ShakeOut began when the USGS partnered with the California Geological Survey, Southern California Earthquake Center and many other organizations to br...

In many regions, especially mountainous areas with heavy rainfall and long interseismic periods, the earthquake hazard may be unknown or underestimated on active structures that do not traverse significant expanses of Quaternary deposits. The region surrounding the Beichuan fault zone, which ruptured as a result of the May 12th, 2008, M 7.9 Wenchua...