ALBERT

Description: The distribution of deformation within the Basin and Range province was determined from 1992, 1996, and 1998 surveys of a dense, 800-kilometer-aperture, Global Positioning System network. Internal deformation generally follows the pattern of Holocene fault distribution and is concentrated near the western extremity of the province, with lesser amounts focused near the eastern boundary. Little net deformation occurs across the central 500 kilometers of the network in western Utah and eastern Nevada. Concentration of deformation adjacent to the rigid Sierra Nevada block indicates that external plate-driving forces play an important role in driving deformation, modulating the extensional stress field generated by internal buoyancy forces that are due to lateral density gradients and topography near the province boundaries.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Thatcher -- Foulger -- Julian -- Svarc -- Quilty -- Bawden -- New York, N.Y. -- Science. 1999 Mar 12;283(5408):1714-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉U.S. Geological Survey, MS/977, Menlo Park, CA 94025, USA. Department of Geological Sciences, University of Durham, Science Laboratories, South Road, Durham DH1 3LE, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10073932" target="_blank"〉PubMed〈/a〉

Description: The Gorkha earthquake (magnitude 7.8) on 25 April 2015 and later aftershocks struck South Asia, killing ~9000 people 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 assessment of the geomorphic, tectonic, and lithologic controls on quake-induced landslides. Timely analysis and communication aided response and recovery and informed decision-makers. We mapped 4312 coseismic and postseismic landslides. We also surveyed 491 glacier lakes for earthquake damage but found only nine landslide-impacted lakes and no visible satellite evidence of outbursts. Landslide densities correlate with slope, peak ground acceleration, surface downdrop, and specific metamorphic lithologies and large plutonic intrusions.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kargel, J S -- Leonard, G J -- Shugar, D H -- Haritashya, U K -- Bevington, A -- Fielding, E J -- Fujita, K -- Geertsema, M -- Miles, E S -- Steiner, J -- Anderson, E -- Bajracharya, S -- Bawden, G W -- Breashears, D F -- Byers, A -- Collins, B -- Dhital, M R -- Donnellan, A -- Evans, T L -- Geai, M L -- Glasscoe, M T -- Green, D -- Gurung, D R -- Heijenk, R -- Hilborn, A -- Hudnut, K -- Huyck, C -- Immerzeel, W W -- Liming, Jiang -- Jibson, R -- Kaab, A -- Khanal, N R -- Kirschbaum, D -- Kraaijenbrink, P D A -- Lamsal, D -- Shiyin, Liu -- Mingyang, Lv -- McKinney, D -- Nahirnick, N K -- Zhuotong, Nan -- Ojha, S -- Olsenholler, J -- Painter, T H -- Pleasants, M -- Pratima, K C -- Yuan, Q I -- Raup, B H -- Regmi, D -- Rounce, D R -- Sakai, A -- Donghui, Shangguan -- Shea, J M -- Shrestha, A B -- Shukla, A -- Stumm, D -- van der Kooij, M -- Voss, K -- Xin, Wang -- Weihs, B -- Wolfe, D -- Lizong, Wu -- Xiaojun, Yao -- Yoder, M R -- Young, N -- New York, N.Y. -- Science. 2016 Jan 8;351(6269):aac8353. doi: 10.1126/science.aac8353. Epub 2015 Dec 16.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Hydrology and Water Resources, University of Arizona, Tucson, AZ, USA. kargel@hwr.arizona.edu dshugar@uw.edu uharitashya1@udayton.edu. ; Department of Hydrology and Water Resources, University of Arizona, Tucson, AZ, USA. ; School of Interdisciplinary Arts and Sciences, University of Washington Tacoma, Tacoma, WA, USA. kargel@hwr.arizona.edu dshugar@uw.edu uharitashya1@udayton.edu. ; Department of Geology, University of Dayton, Dayton, OH, USA. kargel@hwr.arizona.edu dshugar@uw.edu uharitashya1@udayton.edu. ; Ministry of Forests, Lands and Natural Resource Operations, Prince George, BC, Canada. ; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA. ; Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan. ; Scott Polar Research Institute, University of Cambridge, Cambridge, UK. ; Institute of Environmental Engineering, Federal Institute of Technology-ETH, Zurich, Switzerland. ; NASA Marshall Space Flight Center, Huntsville, AL, USA. ; International Centre for Integrated Mountain Development, Kathmandu, Nepal. ; NASA Headquarters, Washington, DC, USA. ; GlacierWorks, Marblehead, MA, USA. ; The Mountain Institute, Elkins, WV, USA. ; U.S. Geological Survey, Menlo Park, CA, USA. ; Central Department of Geology, Tribhuvan University, Kirtipur, Kathmandu, Nepal. ; Department of Geography, University of Victoria, Victoria, BC, Canada. ; CVA Engineering, Suresnes, France. ; Earthquake Science Center, U.S. Geological Survey, Pasadena, CA, USA. ; ImageCat, Long Beach, CA, USA. ; Faculty of Geosciences, Utrecht University, Utrecht, Netherlands. ; State Key Laboratory of Geodesy and Earth's Dynamics, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan, Hubei Province, China. ; U.S. Geological Survey, Golden, CO, USA. ; Department of Geosciences, University of Oslo, Blindern, Oslo, Norway. ; Hydrological Sciences Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD, USA. ; Cold and Arid Regions of Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, China. ; School of Earth Sciences and Engineering, Nanjing University, Nanjing, China. ; Department of Civil, Architectural and Environmental Engineering, University of Texas at Austin, Austin, TX, USA. ; School of Geography Science, Nanjing Normal University, Nanjing, China. ; Department of Geography, Texas A&M University, College Station, TX, USA. ; Department of Geology, University of Dayton, Dayton, OH, USA. ; Arizona Remote Sensing Center, School of Natural Resources and the Environment, University of Arizona, Tucson, AZ, USA. ; National Snow and Ice Data Center, University of Colorado, Boulder, CO, USA. ; Himalayan Research Center, Kathmandu, Nepal. ; Environmental and Water Resources Engineering, University of Texas at Austin, Austin, TX, USA. ; Wadia Institute of Himalayan Geology, Dehradun, India. ; MacDonald Dettwiler and Associates-GSI, Ottawa, Ontario, Canada. ; Department of Geography, University of California, Santa Barbara, Santa Barbara, CA, USA. ; College of Architecture and Urban Planning, Hunan University of Science and Technology, Xiangtan, China. ; Geography Department, Kansas State University, Manhattan, KS, USA. ; Global Land Ice Measurements from Space (GLIMS) Steward, Alaska Region, Anchorage, AK, USA. ; College of Geographical Science and Environment, Northwest Normal University, China. ; Department of Physics, University of California, Davis, Davis, CA, USA. ; Antarctic Climate and Ecosystems Cooperative Research Centre, University of Tasmania, Hobart, TAS, Australia.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26676355" target="_blank"〉PubMed〈/a〉

Description: 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.

Description: The moment magnitude (M w ) 7.0 12 January 2010 Haiti earthquake is the first major earthquake for which a large-footprint LiDAR (light detection and ranging) survey was acquired within several weeks of the event. Here, we describe the use of virtual reality data visualization to analyze massive amounts (67 GB on disk) of multiresolution terrain data during the rapid scientific response to a major natural disaster. In particular, we describe a method for conducting virtual field work using both desktop computers and a 4-sided, 22 m 3 CAVE immersive virtual reality environment, along with KeckCAVES (Keck Center for Active Visualization in the Earth Sciences) software tools LiDAR Viewer, to analyze LiDAR point-cloud data, and Crusta, for 2.5 dimensional surficial geologic mapping on a bare-earth digital elevation model. This system enabled virtual field work that yielded remote observations of the topographic expression of active faulting within an ~75-km-long section of the eastern Enriquillo–Plantain Garden fault spanning the 2010 epicenter. Virtual field observations indicated that the geomorphic evidence of active faulting and ancient surface rupture varies along strike. Landform offsets of 6–50 m along the Enriquillo–Plantain Garden fault east of the 2010 epicenter and closest to Port-au-Prince attest to repeated recent surface-rupturing earthquakes there. In the west, the fault trace is well defined by displaced landforms, but it is not as clear as in the east. The 2010 epicenter is within a transition zone between these sections that extends from Grand Goâve in the west to Fayette in the east. Within this transition, between L'Acul (lat 72°40'W) and the Rouillone River (lat 72°35'W), the Enriquillo–Plantain Garden fault is undefined along an embayed low-relief range front, with little evidence of recent surface rupture. Based on the geometry of the eastern and western faults that show evidence of recent surface rupture, we propose that the 2010 event occurred within a stepover that appears to have served as a long-lived boundary between rupture segments, explaining the lack of 2010 surface rupture. This study demonstrates how virtual reality–based data visualization has the potential to transform rapid scientific response by enabling virtual field studies and real-time interactive analysis of massive terrain data sets.

Description: We use data from two seismic networks and satellite interferometric synthetic aperture radar (InSAR) imagery to characterize the 22 December 2003 M (sub w) 6.5 San Simeon earthquake sequence. Absolute locations for the mainshock and nearly 10,000 aftershocks were determined using a new three-dimensional (3D) seismic velocity model; relative locations were obtained using double difference. The mainshock location found using the 3D velocity model is 35.704 degrees N, 121.096 degrees W at a depth of 9.7+ or -0.7 km. The aftershocks concentrate at the northwest and southeast parts of the aftershock zone, between the mapped traces of the Oceanic and Nacimiento fault zones. The northwest end of the mainshock rupture, as defined by the aftershocks, projects from the mainshock hypocenter to the surface a few kilometers west of the mapped trace of the Oceanic fault, near the Santa Lucia Range front and the 〉5 mm postseismic InSAR imagery contour. The Oceanic fault in this area, as mapped by Hall (1991), is therefore probably a second-order synthetic thrust or reverse fault that splays upward from the main seismogenic fault at depth. The southeast end of the rupture projects closer to the mapped Oceanic fault trace, suggesting much of the slip was along this fault, or at a minimum is accommodating much of the postseismic deformation. InSAR imagery shows approximately 72 mm of postseismic uplift in the vicinity of maximum coseismic slip in the central section of the rupture, and approximately 48 and approximately 45 mm at the northwest and southeast end of the aftershock zone, respectively. From these observations, we model a approximately 30-km-long northwest-trending northeast-dipping mainshock rupture surface--called the mainthrust--which is likely the Oceanic fault at depth, a approximately 10-km-long southwest-dipping backthrust parallel to the mainthrust near the hypocenter, several smaller southwest-dipping structures in the southeast, and perhaps additional northeast-dipping or subvertical structures southeast of the mainshock plane. Discontinuous backthrust features opposite the mainthrust in the southeast part of the aftershock zone may offset the relic Nacimiento fault zone at depth. The InSAR data image surface deformation associated with both aseismic slip and aftershock production on the mainthrust and the backthrusts at the northwest and southeast ends of the aftershock zone. The well-defined mainthrust at the latitude of the epicenter and antithetic backthrust illuminated by the aftershock zone indicate uplift of the Santa Lucia Range as a popup block; aftershocks in the southeast part of the zone also indicate a popup block, but it is less well defined. The absence of backthrust features in the central part of the zone suggests range-front uplift by fault-propagation folding, or backthrusts in the central part were not activated during the mainshock.

Description: High-resolution seismic-reflection and seismic-refraction imaging, combined with existing borehole, earthquake, and paleoseismic trenching data, suggest that the Santa Monica fault zone in Los Angeles consists of multiple strands from several kilometers depth to the near surface. We interpret our seismic data as showing two shallow-depth low-angle fault strands and multiple near-vertical ( approximately 85 degrees ) faults in the upper 100 m. One of the low-angle faults dips northward at about 28 degrees and approaches the surface at the base of a topographic scarp on the grounds of the Wadsworth VA Hospital (WVAH). The other principal low-angle fault dips northward at about 20 degrees and projects toward the surface about 200 m south of the topographic scarp, near the northernmost areas of the Los Angeles Basin that experienced strong shaking during the 1994 Northridge earthquake. The 20 degrees north-dipping low-angle fault is also apparent on a previously published seismic-reflection image by Pratt et al. (1998) and appears to extend northward to at least Wilshire Boulevard, where the fault may be about 450 m below the surface. Slip rates determined at the WVAH site could be significantly underestimated if it is assumed that slip occurs only on a single strand of the Santa Monica fault or if it is assumed that the near-surface faults dip at angles greater than 20-28 degrees . At the WVAH, tomographic velocity modeling shows a significant decrease in velocity across near-surface strands of the Santa Monica fault. P-wave velocities range from about 500 m/sec at the surface to about 4500 m/sec within the upper 50 m on the north side of the fault zone at WVAH, but maximum measured velocities on the south side of the low-angle fault zone at WVAH are about 3500 m/sec. These refraction velocities compare favorably with velocities measured in nearby boreholes by Gibbs et al. (2000). This study illustrates the utility of combined seismic-reflection and seismic-refraction methods, which allow more accurate reflection imaging and compositional estimations across areas with highly variable velocities, a property that is characteristic of most fault zones.