Seismic Tomography Uses Earthquake Waves to Probe the Inner Earth CORE CONCEPTS Sid Perkins, Science Writer
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Insights from the P Wave Travel Time Tomography in the Upper Mantle Beneath the Central Philippines
remote sensing Article Insights from the P Wave Travel Time Tomography in the Upper Mantle Beneath the Central Philippines Huiyan Shi 1 , Tonglin Li 1,*, Rui Sun 2, Gongbo Zhang 3, Rongzhe Zhang 1 and Xinze Kang 1 1 College of Geo-Exploration Science and Technology, Jilin University, No.938 Xi Min Zhu Street, Changchun 130026, China; [email protected] (H.S.); [email protected] (R.Z.); [email protected] (X.K.) 2 CNOOC Research Institute Co., Ltd., Beijing 100028, China; [email protected] 3 State Key Laboratory of Geodesy and Earth’s Dynamics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China; [email protected] * Correspondence: [email protected] Abstract: In this paper, we present a high resolution 3-D tomographic model of the upper mantle obtained from a large number of teleseismic travel time data from the ISC in the central Philippines. There are 2921 teleseismic events and 32,224 useful relative travel time residuals picked to compute the velocity structure in the upper mantle, which was recorded by 87 receivers and satisfied the requirements of teleseismic tomography. Crustal correction was conducted to these data before inversion. The fast-marching method (FMM) and a subspace method were adopted in the forward step and inversion step, respectively. The present tomographic model clearly images steeply subduct- ing high velocity anomalies along the Manila trench in the South China Sea (SCS), which reveals a gradual changing of the subduction angle and a gradual shallowing of the subduction depth from the north to the south. -
Earthscope Project Plan
○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ A NEW VIEW INTO EARTH ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ PROJECT PLAN ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ A NEW VIEW INTO EARTH ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ PROJECT PLAN OCTOBER 2001 ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ EarthScope Working Group Thomas Henyey (Chair) ............. University of Southern California Thomas Herring.......................... Massachusetts Institute of Technology Steve Hickman ............................ United States Geological Survey Thomas Jordan .......................... University of Southern California John McRaney (Secretary) ........ University of Southern California Anne Meltzer............................... Lehigh University J. Bernard Minster...................... University of California, San Diego Dennis Nielson ........................... DOSECC Paul Rosen .................................. Jet Propulsion Laboratory Paul Silver ................................... Carnegie Institution of Washington Mark Simons............................... California Institute of Technology David Simpson ........................... IRIS Robert Smith............................... University of Utah Wayne Thatcher ......................... United States Geological Survey Mark Zoback ............................... Stanford University ○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ Contents○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○ -
Overview of Earthscope: Usarray and the Plate Boundary Observatory
Overview of EarthScope: USArray and the Plate Boundary Observatory Bob Lillie EarthScope Education/Outreach Manager EarthScope National Office Oregon State University EarthScope Cascadia Interpretive Workshop Mt. Rainier National Park Education Center Tahoma Woods, Washington April 7-10, 2008 www.earthscope.org 7 11 15 5 6 14 NATIONAL PARKLANDS 4 10 1317 12 3 9 18 2 8 16 1 Introductions (About 5 at a time ) 1. Who? Where from? Why this workshop? 2. What’s your favorite park - other than your own - and why? 20 19 Parks and Plates ©2005 Robert J. Lillie Acknowledgements • Funded by the National Science Foundation • A collaborative effort by the Incorporated Institutions for Seismology (IRIS), UNAVCO Inc., and Stanford University, with contributions from the U. S. Geological Survey, NASA, and other organizations What is EarthScope? A nationwide program to ….. • Explore the structure and evolution of the North American continent • Understand processes that cause earthquakes and volcanic eruptions Drillhole across San Andreas Fault 875 GPS Instruments 175 Borehole Strainmeters 5 Long-Baseline Laser Strainmeters 400 Seismometers at 2,000 sites 100 Permanent Seismometers USArray (Includes 400 Transportable Seismometers) USArray (Includes 400 Transportable Seismometers) IRIS Washington, DC Station occupies a site for 1½ - 2 years 10 years to leap-frog array across the country Plate Boundary Observatory (PBO) • GPS Instruments • Strainmeters UNAVCO Boulder, CO San Andreas Fault SAFOD Observatory at Depth (SAFOD) Stanford University SAN ANDREAS FAULT ZONE ANDREAS FAULT SAN EarthScope National Office (ESNO) To assist the EarthScope community in products and training for science and outreach. For the next few years, EarthScope is focused on the west. -
The East African Rift System in the Light of KRISP 90
ELSEVIER Tectonophysics 236 (1994) 465-483 The East African rift system in the light of KRISP 90 G.R. Keller a, C. Prodehl b, J. Mechie b,l, K. Fuchs b, M.A. Khan ‘, P.K.H. Maguire ‘, W.D. Mooney d, U. Achauer e, P.M. Davis f, R.P. Meyer g, L.W. Braile h, 1.0. Nyambok i, G.A. Thompson J a Department of Geological Sciences, University of Texas at El Paso, El Paso, TX 79968-0555, USA b Geophysikalisches Institut, Universitdt Karlwuhe, Hertzstrasse 16, D-76187Karlsruhe, Germany ’ Department of Geology, University of Leicester, University Road, Leicester LEl 7RH, UK d U.S. Geological Survey, Office of Earthquake Research, 345 Middlefield Road, Menlo Park, CA 94025, USA ’ Institut de Physique du Globe, Universite’ de Strasbourg, 5 Rue Ret& Descartes, F-67084 Strasbourg, France ‘Department of Earth and Space Sciences, University of California at Los Angeles, Los Angeles, CA 90024, USA ’ Department of Geology and Geophysics, University of Wuconsin at Madison, Madison, WI 53706, USA h Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, IN 47907, USA i Department of Geology, University of Nairobi, P.O. Box 14576, Nairobi, Kenya ’ Department of Geophysics, Stanford University, Stanford, CA 94305, USA Received 21 September 1992; accepted 8 November 1993 Abstract On the basis of a test experiment in 1985 (KRISP 85) an integrated seismic-refraction/ teleseismic survey (KRISP 90) was undertaken to study the deep structure beneath the Kenya rift down to depths of NO-150 km. This paper summarizes the highlights of KRISP 90 as reported in this volume and discusses their broad implications as well as the structure of the Kenya rift in the general framework of other continental rifts. -
Full-Text PDF (Final Published Version)
Pritchard, M. E., de Silva, S. L., Michelfelder, G., Zandt, G., McNutt, S. R., Gottsmann, J., West, M. E., Blundy, J., Christensen, D. H., Finnegan, N. J., Minaya, E., Sparks, R. S. J., Sunagua, M., Unsworth, M. J., Alvizuri, C., Comeau, M. J., del Potro, R., Díaz, D., Diez, M., ... Ward, K. M. (2018). Synthesis: PLUTONS: Investigating the relationship between pluton growth and volcanism in the Central Andes. Geosphere, 14(3), 954-982. https://doi.org/10.1130/GES01578.1 Publisher's PDF, also known as Version of record License (if available): CC BY-NC Link to published version (if available): 10.1130/GES01578.1 Link to publication record in Explore Bristol Research PDF-document This is the final published version of the article (version of record). It first appeared online via Geo Science World at https://doi.org/10.1130/GES01578.1 . Please refer to any applicable terms of use of the publisher. University of Bristol - Explore Bristol Research General rights This document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/red/research-policy/pure/user-guides/ebr-terms/ Research Paper THEMED ISSUE: PLUTONS: Investigating the Relationship between Pluton Growth and Volcanism in the Central Andes GEOSPHERE Synthesis: PLUTONS: Investigating the relationship between pluton growth and volcanism in the Central Andes GEOSPHERE; v. 14, no. 3 M.E. Pritchard1,2, S.L. de Silva3, G. Michelfelder4, G. Zandt5, S.R. McNutt6, J. Gottsmann2, M.E. West7, J. Blundy2, D.H. -
Geophysical Journal International
Geophysical Journal International Geophys. J. Int. (2017) 209, 1892–1905 doi: 10.1093/gji/ggx133 Advance Access publication 2017 April 1 GJI Seismology Surface wave imaging of the weakly extended Malawi Rift from ambient-noise and teleseismic Rayleigh waves from onshore and lake-bottom seismometers N.J. Accardo,1 J.B. Gaherty,1 D.J. Shillington,1 C.J. Ebinger,2 A.A. Nyblade,3 G.J. Mbogoni,4 P.R.N. Chindandali,5 R.W. Ferdinand,6 G.D. Mulibo,6 G. Kamihanda,4 D. Keir,7,8 C. Scholz,9 K. Selway,10 J.P. O’Donnell,11 G. Tepp,12 R. Gallacher,7 K. Mtelela,6 J. Salima5 and A. Mruma4 1Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA. E-mail: [email protected] 2Department of Earth and Environmental Sciences, Tulane University, New Orleans, LA 70118,USA 3Department of Geosciences, The Pennsylvania State University, State College, PA 16802,USA 4Geological Survey of Tanzania, Dodoma, Tanzania 5Geological Survey Department of Malawi, Zomba, Malawi 6Department of Geology, University of Dar es Salaam, Dar es Salaam, Tanzania 7National Oceanography Centre Southampton, University of Southampton, Southampton S017 1BJ, United Kingdom 8Dipartimento di Scienzedella Terra, Universita degli Studi di Firenze, Florence 50121,Italy 9Department of Earth Sciences, Syracuse University, New York, NY 13210,USA 10Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia 11School of Earth and Environment, University of Leeds, Leeds, LS29JT, United Kingdom 12Alaska Volcano Observatory, U.S. Geological Survey, Anchorage, AK 99775,USA Accepted 2017 March 28. Received 2017 March 13; in original form 2016 October 12 SUMMARY Located at the southernmost sector of the Western Branch of the East African Rift System, the Malawi Rift exemplifies an active, magma-poor, weakly extended continental rift. -
What Is Earthscope's Plan for Yukon?
What is EarthScope? The United States National Science Foundation (NSF) has provided funding for a large collaborative research project known as EarthScope. The purpose is to study the North American continent by deploying seismic (earthquake) sensors through the USArray program and GPS instruments through the Plate Boundary Observatory (PBO). Since 2003, USArray has installed temporary networks of seismometers known as the Transportable Array (TA) across the contiguous United States (the lower 48 states), and in southern Ontario and Quebec. The TA consists of 400 high-quality, The map above shows the locations of the Transportable Array portable seismic stations that are placed at temporary sites. seismometers that were installed between 2004 and 2013. Most Unless adopted and made into a permanent installation, each were removed and re-located as the array progressed from west to USArray instrument is picked up and moved after 18 to 24 east. months to the next carefully spaced array location. When completed, more than 2,000 locations will have been occupied during the USArray program. The earthquake data gathered from these sites result in more accurate maps of earthquake locations and are analyzed to produce high-resolution images of Earth’s interior. All data are freely accessible from EarthScope. What is EarthScope’s plan for Yukon? In 2013 and 2014, USArray installed a total of 25 stations in Alaska. Beginning in 2015, USArray is proposing to place temporary seismic stations at approximately 32 locations across the Yukon, ve in western Northwest Territories, and six in northern British Columbia. It will take three years (2015-2017) to achieve full deployment. -
Trimble Selected for UNAVCO's Earthscope PBO Network Trimble GPS to Monitor the Active Tectonic Boundary of Western North America
Trimble Selected for UNAVCO's EarthScope PBO Network Trimble GPS to Monitor the Active Tectonic Boundary of Western North America SUNNYVALE, Calif., Feb. 26, 2004 -- Trimble (NASDAQ: TRMB) announced today that UNAVCO, Inc., has selected the Company to provide 875 Trimble NetRSTM Global Positioning System (GPS) reference station receivers over five years. The reference station receivers will be used as part of the Plate Boundary Observatory (PBO) network, a major component of the EarthScope Program sponsored by the National Science Foundation (NSF). About the EarthScope Program The EarthScope facility is a multi-purpose array of geodetic and seismic instruments and a borehole observatory that will greatly expand the observational capabilities of the Earth sciences to lead to advancements in understanding the structure, evolution and dynamics of the North American continent. This is made possible by theoretical, computational, and technological advances in geophysics, satellite geodesy, information technology, drilling technology and downhole instrumentation. The EarthScope observational facility provides a framework for broad, integrated studies across the Earth sciences, including research on fault properties and the earthquake process, crustal strain transfer, magmatic and hydrous fluids in the crust and mantle, plate boundary processes, large-scale continental deformation, continental structure and evolution, and composition and structure of the deep-Earth. In addition, EarthScope offers a centralized forum for Earth science education at all levels and an excellent opportunity to develop cyber infrastructure to integrate, distribute and analyze diverse data sets. About PBO The Plate Boundary Observatory (PBO) is a geodetic observatory designed to study the three-dimensional strain field resulting from the Earth's tectonic movements across the active boundary zone between the Pacific and North American plates in the western United States. -
Seismic Tomography Shows That Upwelling Beneath Iceland Is Confined to the Upper Mantle
Geophys. J. Int. (2001) 146, 504–530 Seismic tomography shows that upwelling beneath Iceland is confined to the upper mantle G. R. Foulger,1 M. J. Pritchard,1 B. R. Julian,2 J. R. Evans,2 R. M. Allen,3 G. Nolet,3 W. J. Morgan,3 B. H. Bergsson,4 P. Erlendsson,4 S. Jakobsdottir,4 S. Ragnarsson,4 R. Stefansson4 and K. Vogfjo¨rd5 1 Department of Geological Sciences, University of Durham, Durham, DH1 3LE, UK. E-mail: [email protected] 2 US Geological Survey, 345 Middlefield Road., Menlo Park, CA 94025, USA 3 Department of Geological and Geophysical Sciences, Guyot Hall, Princeton University, Princeton, NJ 08544–5807, USA 4 Meteorological Office of Iceland, Bustadavegi 9, Reykjavik, Iceland 5 National Energy Authority, Grensasvegi 9, Reykjavik, Iceland Accepted 2001 April 3. Received 2001 March 19; in original form 2000 August 1 SUMMARY We report the results of the highest-resolution teleseismic tomography study yet performed of the upper mantle beneath Iceland. The experiment used data gathered by the Iceland Hotspot Project, which operated a 35-station network of continuously recording, digital, broad-band seismometers over all of Iceland 1996–1998. The structure of the upper mantle was determined using the ACH damped least-squares method and involved 42 stations, 3159 P-wave, and 1338 S-wave arrival times, including the phases P, pP, sP, PP, SP, PcP, PKIKP, pPKIKP, S, sS, SS, SKS and Sdiff. Artefacts, both perceptual and parametric, were minimized by well-tested smoothing techniques involving layer thinning and offset-and-averaging. Resolution is good beneath most of Iceland from y60 km depth to a maximum of y450 km depth and beneath the Tjornes Fracture Zone and near-shore parts of the Reykjanes ridge. -
Chapter 2 the Evolution of Seismic Monitoring Systems at the Hawaiian Volcano Observatory
Characteristics of Hawaiian Volcanoes Editors: Michael P. Poland, Taeko Jane Takahashi, and Claire M. Landowski U.S. Geological Survey Professional Paper 1801, 2014 Chapter 2 The Evolution of Seismic Monitoring Systems at the Hawaiian Volcano Observatory By Paul G. Okubo1, Jennifer S. Nakata1, and Robert Y. Koyanagi1 Abstract the Island of Hawai‘i. Over the past century, thousands of sci- entific reports and articles have been published in connection In the century since the Hawaiian Volcano Observatory with Hawaiian volcanism, and an extensive bibliography has (HVO) put its first seismographs into operation at the edge of accumulated, including numerous discussions of the history of Kīlauea Volcano’s summit caldera, seismic monitoring at HVO HVO and its seismic monitoring operations, as well as research (now administered by the U.S. Geological Survey [USGS]) has results. From among these references, we point to Klein and evolved considerably. The HVO seismic network extends across Koyanagi (1980), Apple (1987), Eaton (1996), and Klein and the entire Island of Hawai‘i and is complemented by stations Wright (2000) for details of the early growth of HVO’s seismic installed and operated by monitoring partners in both the USGS network. In particular, the work of Klein and Wright stands and the National Oceanic and Atmospheric Administration. The out because their compilation uses newspaper accounts and seismic data stream that is available to HVO for its monitoring other reports of the effects of historical earthquakes to extend of volcanic and seismic activity in Hawai‘i, therefore, is built Hawai‘i’s detailed seismic history to nearly a century before from hundreds of data channels from a diverse collection of instrumental monitoring began at HVO. -
About the New Madrid Seismic Zone
About the New Madrid Seismic Zone The New Madrid seismic zone (NMSZ) extends more than 120 miles southward from Cairo, Illinois, at the junction of the Mississippi and Ohio rivers, into Arkansas and parts of Kentucky and Tennessee. It roughly follows Interstate 55 through Blytheville down to Marked Tree, Arkansas, crossing four state lines and the Mississippi River in three places as it progresses through some of the richest farmland in the country. The greatest earthquake risk east of the Rocky Mountains is along the NMSZ. Damaging earthquakes are not as frequent as in California, but when they do occur, the destruction covers more than 15 times the area because of the underlying geology and soil conditions prevalent in the region. The zone is active, averaging about 200 earthquakes per year, though most of them are too small to be felt. With modern seismic networks, the capability to detect earthquakes has greatly increased, and many more very small earthquakes are being detected now than in the past. There is a common misconception that the number of earthquakes has increased over the years, but the increase is due to more sophisticated recording methods that can detect earthquakes that were previously unrecorded. The history of the region tells us, however, that the earthquake risk is the most serious potential disaster we could face. In the winter of 1811-1812, a series of very large earthquakes occurred along the fault system buried deep within the NMSZ. Using felt information reported in newspapers and from eyewitness accounts of effects, magnitudes have been estimated to be 7.8, 8.0, and 8.1. -
Crustal Structure of the Eastern Anatolia Region (Turkey) Based on Seismic Tomography
geosciences Article Crustal Structure of the Eastern Anatolia Region (Turkey) Based on Seismic Tomography Irina Medved 1,2,* , Gulten Polat 3 and Ivan Koulakov 1 1 Trofimuk Institute of Petroleum Geology and Geophysics SB RAS, Prospekt Koptyuga, 3, 630090 Novosibirsk, Russia; [email protected] 2 Sobolev Institute of Geology and Mineralogy SB RAS, Prospekt Koptyuga, 3, 630090 Novosibirsk, Russia 3 Department of Civil Engineering, Yeditepe University, 26 Agustos Yerleskesi, 34755 Istanbul, Turkey; [email protected] * Correspondence: [email protected]; Tel.: +7-952-922-49-67 Abstract: Here, we investigated the crustal structure beneath eastern Anatolia, an area of high seismicity and critical significance for earthquake hazards in Turkey. The study was based on the local tomography method using data from earthquakes that occurred in the study area provided by the Turkiye Cumhuriyeti Ministry of Interior Disaster and Emergency Management Directorate Earthquake Department Directorate of Turkey. The dataset used for tomography included the travel times of 54,713 P-waves and 38,863 S-waves from 6355 seismic events. The distributions of the resulting seismic velocities (Vp, Vs) down to a depth of 60 km demonstrate significant anomalies associated with the major geologic and tectonic features of the region. The Arabian plate was revealed as a high-velocity anomaly, and the low-velocity patterns north of the Bitlis suture are mostly associated with eastern Anatolia. The upper crust of eastern Anatolia was associated with a ~10 km thick high-velocity anomaly; the lower crust is revealed as a wedge-shaped low-velocity anomaly. This kind of seismic structure under eastern Anatolia corresponded to the hypothesized existence of Citation: Medved, I.; Polat, G.; a lithospheric window beneath this collision zone, through which hot material of the asthenosphere Koulakov, I.