We have partnered with SinoProbe, the Chinese national scientific program led by CAGS (Chinese Academy of Geological Sciences) to study the lithosphere. We are helping to design experiments and analyze and interpret the resultant near-vertical and wide-angle seismic profiles across the Karakoram Fault (and elsewhere in Tibet). In complementary geochemical studies we are working with CAGS and NGRI (National Geophysical Research Institute of India) to sample thermal springs for mantle-sourced helium (3He), and analyzing these samples at Lawrence Berkeley National Laboratories. High 3He/3He ratios along the Karakoram fault demonstrate that this fault accesses Tibetan mantle and marks the 'mantle suture' in western Tibet.
Following the devastating Gorkha earthquake in April 2015, Stanford sent seismometers to record aftershocks that we are now using to image the rupture surface of the earthquake. Ultimately 46 instruments were deployed for 11 months, providing a unique dataset. Subsequent outreach activities focused on training staff at Nepal's Department of Mines and Geology, and graduate students at Tribhuvan University, Kathmandu. Now we are planning for a wider imaging experiment to understand where and how the next Himalayan Megaquake may occur.
HIMPROBE is an Indian national project, active since 2000, to create a NW-Himalayan geotransect from the Sub-Himalaya to the Karakoram Range. Framework broadband seismology, broadband MT, the first phase of seismic reflection, and a comprehensive potential-field transect have already been conducted. Coupled with geological investigations, these projects make this area more data-rich than most regions of the orogen.We have worked with NGRI (National Geophysical Research Institute) scientists on broadband passive seismic data, seismic reflection data, and geochemical sampling; and with IIT Roorkee scientists on geologic sampling and radiometric dating. At Stanford, we are using broadband seismic data from HIMPROBE to reveal lithospheric structure. We have analyzed the dispersion of fundamental mode Rayleigh waves and identified a low-velocity zone in the mid-crust north of the Indus-Tsangpo suture (ITS) coincident with a zone of high electrical conductivty observed by magnetotelluric measurements - a result consistent with active channel flow outwards from the Tibet Plateau. Our CCP images of broadband data from the Garwhal Himalaya suggest a major role for fluids in controlling the seismogenesis of the Main Himalayan Thrust.
Project INDEPTH (International Deep Profiling of Tibet and the Himalaya) is a multidisciplinary geophysical and geological investigation of the Himalayas and Tibet. Field projects associated with INDEPTH I, II, and III took place between 1992-2000 and covered Southern to Central Tibet. INDEPTH IV’s field season began in May/June 2007 with the acquisition of an active source seismic profile in NE Tibet.Previous seismic studies have significantly elucidated the response of Asia to the impact of the Indian subcontinent from Southern to Central Tibet. The INDEPTH (International Deep Profiling of Tibet and the Himalaya) IV transect across the northeast boundary of Tibet completes a profile across the entire Tibetan plateau and is expected to clarify the subduction of Asian continental crust beneath the Tibetan Plateau along its northern margin and to probe the geometry and depth extent of the Kunlun Fault.The collision of the Indian and Asian plates over the past ~55 Ma created the Himalaya and uplifted the Tibetan Plateau. During convergence both plates experienced significant deformation and crustal thickening. Debate continues regarding how Asia has responded to the embedding of the Indian subcontinent with theories including indentor tectonics leading to terrane escape along lithospheric strike-slip faults and lower-crustal ductile flow.INDEPTH IV incorporates a wide variety of geophysical data. Our field studies commenced in summer 2007 with the acquisition of a 270 km, high-resolution controlled-source seismic profile across the Kunlun suture and the deployment of broadband seismometers across the Kunlun and Jinsha sutures for eighteen months recording. Magnetotellurics and geological mapping in 2008 will complement the seismic acquisition.Chinese institutions involved in the multinational collaboration include the Chinese Academy of Geological Sciences (CAGS), Chengdu University of Technology, and China University of Geosciences. North American and European institutions include Cornell University, Stanford University, GeoForschungsZentrum Potsdam, Missouri, New Mexico State University, Cambridge, Alberta, Dublin Institute for Advanced Studies, University of Kiel, and University of Haifa.
The Southern California Continental Borderland records a complex history of the transition from a Cretaceous subduction to Miocene rifting to the current regime of transform tectonics. Tectonic deformation in southern California is currently dominated by the anastamosing faults of the North American-Pacific plate boundary (San Andreas Fault System). Vertical motions of the islands and coastline of southern California are elucidated by the presence of marine terraces (relict shorelines) observed on much of the coastline. Santa Catalina Island is conspicuous in its lack of uplifted marine terraces. Instead Catalina hosts spectacular submerged marine terraces as deep as 350m (~1150ft), in many ways equivalent to uplifted terraces on nearby islands. Catalina's submerged terraces are deeper than sea level fluctuations and therefore require subsidence.My research focuses on the Quaternary tectonics of southern California, with a primary focus on the subsided/subsiding islands of the Channel Islands archipelago. I use high dynamic-range imaging techniques on bathymetric data to investigate seafloor morphology. These data are correlated with ultra high-resolution seismic data and fossil data from core samples to construct a 4D deformation history of a subsided island. Targets for 2014 investigation: Pilgrim Banks, Kidney Bank, and Catalina Island.
Santa Catalina, California
The Salton Trough was formed by past and current relative motions of the Pacific and North American tectonic plates. In its northern edge, the right-lateral transform boundary of the San Andreas Fault system turns into the divergent motion of the East Pacific Rise, which continues south through the Gulf of California. The Salton Trough is highly active: it exhibits a high rate of seismicity; contains major active faults; and geothermal activity is evident on the surface. Faults within the Salton Trough region accommodate together about 80% of the 5 cm/yr of relative Pacific–North American motion. Because the rift is buried beneath a thick pile of Colorado River sediments, surprisingly little is currently known about the total volume of intrusion into the crust and the magma distribution within and beyond the rift margins. This study will lead to a better understanding of magmatic dominated rifts as well as about extensional tectonics in general.In January 2011, students and faculty from Stanford University have deployed a network of 40 seismometers across southernmost California from the Pacific Ocean to the Colorado River. These seismometers recorded earthquakes from around the world for a period of 2 years. The data collected over that two year period will be used to construct an image of the deep structure beneath the region, learning about the location of faults, the distribution of magma, and the thickness of the crust in the area. This will allow us to understand more about the tectonic plate boundary, and how that affects earthquakes and volcanism.
Salton Sea, California
This project will acquire high-resolution seismic data about the Ruby Mountains Core Complex in an effort to understand the processes that occurred during its formation. Information acquired about this area will lead to a better understanding of core complexes in other areas, as well as about extenstional tectonics in general. The Ruby Mountains, part of the Basin and Range in northeastern Nevada, are an excellent target area, as previous work provides geologic information at the surface, and seismic studies have been done in the surrounding area, though not over the Ruby Mountains themselves.A metamorphic core complex is formed when highly deformed lower crustal rocks are exhumed in the footwall of a large detachment fault. Core complexes are common features both in continental extensional provinces such as the Basin and Range and at oceanic spreading centers, but broad questions still remain about their formation. The Ruby Mountains Core Complex has all the characteristic features of a metamorphic core complex, with a domed metamorphic-plutonic footwall, an unmetamorphosed hanging wall, and a mylonitic sub-horizontal sheared detachment separating them.In June 2010, Stanford students deployed a passive broadband seismic array consisting of 50 stations with 5-10 km spacing in a line down the axis of the Ruby Range and two crossing profiles. The stations will collect seismic data for two years, which will be used to create a map of the subsurface in the area that can be used for interpretation.
Ruby Mountains, NV
The Stanford ultra-low frequency electromagnetic (ULFEM) Monitoring Project is recording naturally varying electromagnetic signals adjacent to active earthquake faults, in an attempt to establish whether there is any variation in these signals before or after earthquakes.Our project is collaborative with the U.S. Geological Survey and U.C. Berkeley. Lead scientists are Simon Klemperer (Stanford University), Jonathan Glen (U.S.G.S.) and Darcy Karakelian McPhee (U.S.G.S.)Our initial sites are in the San Francisco Bay Area, monitoring different strands of the San Andreas fault system, and Jasper Ridge (JRSC), Marin Headlands (MHDL), and Briones (BRIB). Related sites in the greater San Francisco Bay Area are operated by U.C. Berkeley and by QuakefinderStanford University, in co-operation with the U.S.G.S. and with assistance from U.C. Berkeley, maintains three sites in the San Francisco Bay Area, monitoring different strands of the San Andreas fault system. These three sites (Jasper Ridge (JRSC), Marin Headlands (MHDL), and Briones (BRIB)) have three orthogonal magnetometers, and JRSC and BRIB additionally have two pairs of orthogonal 100-m horizontal electrodes. Our equipment is sensitive to natural field variations in the frequency (period) range 0.01 to 10 Hz (100 to 0.1 s).Data sampled at 40 Hz are available online from three stations maintained by Stanford University in co-operation with the U.S.G.S and with asistance from U.C. Berkeley: (JRSC) Jasper Ridge Biological Preserve, Stanford University (MHDL) Marin Headlands, Golden Gate National Recreation Area (BRIB) Russell Reservation, Briones Reserve, U.C.and from two stations maintained by U.C. Berkeley with assistance from the U.S.G.S. and Stanford University: (SAO) San Andreas Geophysical Observatory, Hollister (PKD) Bear Valley Ranch,ParkfieldStation metadata can be found at the Berkeley Digital Seismic Network (BDSN) and Northern California Earthquake Data Center (NCEDC) sites including a brief listing of station location and operation dates and a description of each available channel.
San Francisco Bay Area
US-EAGLE (Ethiopia-Afar Geoscientific Lithospheric Experiment) is the US component of the international EAGLE program to investigate modification of lithospheric structure during continental breakup. With US collaborators from UTEP, Penn State and SWMSU we are working with UK scientists from Leicester, London, Leeds and Edinburgh in a comprehensive investigation of the deep structure of the Main Ethiopian Rift, at the point where the archetypal narrow continental rift - the East African Rift - is becoming dominated by magmatism as it progresses towards ocean rifting in the Afar Triangle and southern Red Sea. Katie Keranen (crustal group graduate) and Ewenet Gashawbeza (crustal group graduate) are working on this project. Previously two undergraduates, Andrea Les and Michele Cash, worked on this project and assisted with fieldwork in Ethiopia. For more on the science objectives of the project, click here. In June 2004 Prof. Klemperer co-organized the NSF-funded US-Africa Workshop on Anatomy of Continental Rifts: The evolution of the East African Rift System from nascent extension to continental breakup in Addis Ababa, Ethiopia.
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