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Tong, XP, Sandwell D, Luttrell K, Brooks B, Bevis M, Shimada M, Foster J, Smalley R, Parra H, Soto JCB, Blanco M, Kendrick E, Genrich J, Caccamise DJ.  2010.  The 2010 Maule, Chile earthquake: Downdip rupture limit revealed by space geodesy. Geophysical Research Letters. 37   10.1029/2010gl045805   AbstractWebsite

Radar interferometry from the ALOS satellite captured the coseismic ground deformation associated with the 2010 Mw 8.8 Maule, Chile earthquake. The ALOS interferograms reveal a sharp transition in fringe pattern at similar to 150 km from the trench axis that is diagnostic of the downdip rupture limit of the Maule earthquake. An elastic dislocation model based on ascending and descending ALOS interferograms and 13 near-field 3-component GPS measurements reveals that the coseismic slip decreases more or less linearly from a maximum of 17 m (along-strike average of 6.5 m) at 18 km depth to near zero at 43-48 km depth, quantitatively indicating the downdip limit of the seismogenic zone. The depth at which slip drops to near zero appears to be at the intersection of the subducting plate with the continental Moho. Our model also suggests that the depth where coseismic slip vanishes is nearly uniform along the strike direction for a rupture length of similar to 600 km. The average coseismic slip vector and the interseismic velocity vector are not parallel, which can be interpreted as a deficit in strike-slip moment release. Citation: Tong, X., et al. (2010), The 2010 Maule, Chile earthquake: Downdip rupture limit revealed by space geodesy, Geophys. Res. Lett., 37, L24311, doi:10.1029/2010GL045805.

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Sandwell, DT, Smith WHF, Gille S, Kappel E, Jayne S, Soofi K, Coakley B, Geli L.  2006.  Bathymetry from space: Rationale and requirements for a new, high-resolution altimetric mission. Comptes Rendus Geoscience. 338:1049-1062.   10.1016/j.crte.2006.05.014   AbstractWebsite

Bathymetry is foundational data, providing basic infrastructure for scientific, economic, educational, managerial, and political work. Applications as diverse as tsunami hazard assessment, communications cable and pipeline route planning, resource exploration, habitat management, and territorial claims under the Law of the Sea all require reliable bathymetric maps to be available on demand. Fundamental Earth science questions, such as what controls seafloor shape and how seafloor shape influences global climate, also cannot be answered without bathymetric maps having globally uniform detail. Current bathymetric, charts are inadequate for many of these applications because only a small fraction of the seafloor has been surveyed. Modern multibeam echosounders provide the best resolution, but it would take more than 200 ship-years and billions of dollars to complete the job. The seafloor topography can be charted globally, in five years, and at a cost under $100M. A radar altimeter mounted on an orbiting spacecraft can measure slight variations in ocean surface height, which reflect variations in the pull of gravity caused by seafloor topography. A new satellite altimeter mission, optimized to map the deep ocean bathymetry and gravity field, will provide a global map of the world's deep oceans at a resolution of 6-9 kin. This resolution threshold is critical for a large number of basic science and practical applications, including: determining the effects of bathymetry and seafloor roughness on ocean circulation, mixing, climate, and biological communities, habitats, and mobility; understanding the geologic processes responsible for ocean floor features unexplained by simple plate tectonics, such as abyssal hills, seamounts, microplates, and propagating rifts;. improving tsunami hazard forecast accuracy by mapping the deep-ocean topography that steers tsunami wave energy; mapping the marine gravity field to improve inertial navigation and provide homogeneous coverage of continental margins; providing bathymetric maps for numerous other practical applications, including reconnaissance for submarine cable and pipeline routes, improving tide models, and assessing potential territorial claims to the seabed under the United Nations Convention on the Law of the Sea. Because ocean bathymetry is a fundamental measurement of our planet, there is a broad spectrum of interest from government, the research community, industry, and the general public. Mission requirements. The resolution of the altimetry technique is limited by physical law, not instrument capability. Everything that can be mapped from space can be achieved now, and there is no gain in waiting for technological advances. Mission requirements for Bathymetry from Space are much less stringent and less costly than typical physical oceanography missions. Long-term sea-surface height accuracy is not needed; the fundamental measurement is the slope of the ocean surface to an accuracy of similar to 1 prad (1 mm km(-1)). The main mission requirements are: improved range precision (a factor of two or more improvement in altimeter range precision with respect to current altimeters is needed to reduce the noise due to ocean waves); - fine cross-track spacing and long mission duration (a ground track spacing of 6 km or less is required. A six-year mission would reduce the error by another factor of two); moderate inclination (existing satellite altimeters have relatively high orbital inclinations, thus their resolution of east-west components of ocean slope is poor at low latitudes. The new mission should have an orbital inclination close to 60 degrees or 120 degrees so as to resolve north-south and east-west components almost equally while still covering nearly all the world's ocean area); near-shore tracking (for applications near coastlines, the ability of the instrument to track the ocean surface close to shore, and acquire the surface soon after leaving land, is desirable).

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Keating, B, Cherkis NZ, Fell PW, Handschmacher D, Hey RN, Lazarewicz A, Naar DF, Perry RK, Sandwell D, Schwank DC, Vogt P, Zondek B.  1984.  Field-Tests of Seasat Bathymetric Detections. Marine Geophysical Researches. 7:69-71.   10.1007/bf00305411   AbstractWebsite

Knowledge of the locations and sizes of seamounts is of great importance in applications such as inertial navigation and ocean mining. The quality and density of bathymetry data in the equatorial regions and the southern hemisphere are, unifortunately, highly variable. Our present knowledge of bathymetry, and in particular of seamount locations and characteristics, is based upon ship surveys, which are both time-consuming and expensive. It is likely that a significant number of uncharted seamounts exist throughout the oceans, and remote-sensing techniques may be the most effective means of locating them.

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Becker, JJ, Sandwell DT, Smith WHF, Braud J, Binder B, Depner J, Fabre D, Factor J, Ingalls S, Kim SH, Ladner R, Marks K, Nelson S, Pharaoh A, Trimmer R, Von Rosenberg J, Wallace G, Weatherall P.  2009.  Global Bathymetry and Elevation Data at 30 Arc Seconds Resolution: SRTM30_PLUS. Marine Geodesy. 32:355-371.   10.1080/01490410903297766   AbstractWebsite

A new 30-arc second resolution global topography/bathymetry grid (SRTM30_PLUS) has been developed from a wide variety of data sources. Land and ice topography comes from the SRTM30 and ICESat topography, respectively. Ocean bathymetry is based on a new satellite-gravity model where the gravity-to-topography ratio is calibrated using 298 million edited soundings. The main contribution of this study is the compilation and editing of the raw soundings, which come from NOAA, individual scientists, SIO, NGA, JAMSTEC, IFREMER, GEBCO, and NAVOCEANO. The gridded bathymetry is available for ftp download in the same format as the 33 tiles of SRTM30 topography. There are 33 matching tiles of source identification number to convey the provenance of every grid cell. The raw sounding data, converted to a simple common format, are also available for ftp download.

Wessel, P, Sandwell DT, Kim SS.  2010.  The Global Seamount Census. Oceanography. 23:24-33. AbstractWebsite

Seamounts are active or extinct undersea volcanoes with heights exceeding similar to 100 m. They represent a small but significant fraction of the volcanic extrusive budget for oceanic seafloor and their distribution gives information about spatial and temporal variations in intraplate volcanic activity. In addition, they sustain important ecological communities, determine habitats for fish, and act as obstacles to Currents, thus enhancing tidal energy dissipation and ocean mixing. Mapping the complete global distribution will help constrain models of seamount formation as well as aid in understanding marine habitats and deep ocean circulation. Two approaches have been used to map the global seamount distribution. Depth soundings from single- and multibeam echosounders can provide the most detailed maps with up to 200-m horizontal resolution. However, soundings from the > 5000 publicly available cruises sample only a small fraction of the ocean floor. Satellite altimetry can detect seamounts taller than similar to 1.5 km, and. studies using altimetry have produced seamount catalogues holding almost 13,000 seamounts. Based on the size-frequency relationship for larger seamounts, we predict over 100,000 seamounts > 1 km in height remain uncharted, and speculatively 25 million > 100 m in height. Future altimetry missions could improve on resolution and significantly decrease noise levels, allowing for an even larger number of intermediate (1-1.5-km height) seamounts to be detected. Recent retracking of the radar altimeter waveforms to improve the accuracy of the gravity field has resulted in a twofold increase in resolution. Thus, improved analyses of existing altimetry with better calibration from multibeam bathymetry could also increase census estimates.

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Kaneko, Y, Fialko Y, Sandwell DT, Tong X, Furuya M.  2013.  Interseismic deformation and creep along the central section of the North Anatolian Fault (Turkey): InSAR observations and implications for rate-and-state friction properties. Journal of Geophysical Research-Solid Earth. 118:316-331.   10.1029/2012jb009661   AbstractWebsite

We present high-resolution measurements of interseismic deformation along the central section of the North Anatolian Fault (NAF) in Turkey using interferometric synthetic aperture radar data from the Advanced Land Observing Satellite and Envisat missions. We generated maps of satellite line-of-sight velocity using five ascending Advanced Land Observing Satellite tracks and one descending Envisat track covering the NAF between 31.2 degrees E and 34.3 degrees E. The line-of-sight velocity reveals discontinuities of up to similar to 5 mm/yr across the Ismetpasa segment of the NAF, implying surface creep at a rate of similar to 9 mm/yr; this is a large fraction of the inferred slip rate of the NAF (21-25 mm/yr). The lateral extent of significant surface creep is about 75 km. We model the inferred surface velocity and shallow fault creep using numerical simulations of spontaneous earthquake sequences that incorporate laboratory-derived rate and state friction. Our results indicate that frictional behavior in the Ismetpasa segment is velocity strengthening at shallow depths and transitions to velocity weakening at a depth of 3-6 km. The inferred depth extent of shallow fault creep is 5.5-7 km, suggesting that the deeper locked portion of the partially creeping segment is characterized by a higher stressing rate, smaller events, and shorter recurrence interval. We also reproduce surface velocity in a locked segment of the NAF by fault models with velocity-weakening conditions at shallow depth. Our results imply that frictional behavior in a shallow portion of major active faults with little or no shallow creep is mostly velocity weakening. Citation: Kaneko, Y., Y. Fialko, D. T. Sandwell, X. Tong, and M. Furuya (2013), Interseismic deformation and creep along the central section of the North Anatolian Fault (Turkey): InSAR observations and implications for rate-and-state friction properties, J. Geophys. Res. Solid Earth, 118, 316-331, doi: 10.1029/2012JB009661.

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Koeberl, C, Sharpton VL, Harrison MT, Sandwell D, Murali AV, Burke K.  1990.  The Kara/Ust-Kara twin impact structure; a large-scale impact event in the Late Cretaceous. Special Paper - Geological Society of America. 247( Sharpton VL, Ward PD, Eds.).:233-238., Boulder, CO, United States (USA): Geological Society of America (GSA), Boulder, CO AbstractWebsite
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Sandwell, D.  2007.  Ocean Bathymetry and Plate Tectonics. Our changing planet : the view from space. ( King MD, Parkinson CL, Partington KC, Williams RG, Eds.).:149-152., Cambridge ; New York: Cambridge University Press Abstract

Examines what orbital imagery tells us about the atmosphere, land, ocean, and polar ice caps of our planet and the ways that it changes naturally, and in response to human activity.

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Sandwell, D, Smith B.  2007.  The San Andreas Fault: Adjustments in the Earth's Crust. Our changing planet : the view from space. ( King MD, Parkinson CL, Partington KC, Williams RG, Eds.).:94-96., Cambridge ; New York: Cambridge University Press Abstract

Examines what orbital imagery tells us about the atmosphere, land, ocean, and polar ice caps of our planet and the ways that it changes naturally, and in response to human activity.

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Kilb, D, Keen CS, Newman RL, Kent GM, Sandwell DT, Vernon FL, Johnson CL, Orcutt JA.  2003.  The Visualization Center at Scripps Institution of Oceanography: Education and Outreach. Seismological Research Letters. 74:641-648. AbstractWebsite

The immersive environment of the Visualization Center at Scripps, coupled with the presentation of current seismological research, has great education and outreach potential. Since its March 2002 opening, the Visualization Center at Scripps has had more than 2,500 visitors, and numerous virtual visitors have explored our Web pages, which include streaming QuickTime movies of geophysical data, tutorials on how to use SGI/Mac/Windows registered visualization software, and examples of visualizations developed by SIO researchers and faculty members (http://siovizcenter.ucsd.edu/library.shtml). We will continue to expand the use of the Visualization Center at Scripps for K-12 and informal education, and to use the center to supply geophysical data sets, movies, and research results to as large a group of educators as possible. Our goal is to develop more sustained K-12 educational programs and to generate assessments of the center's programs and the educational products created at the Center.