Publications
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NGA-West2 Research Project NGA-West2 Research Project
The NGA-West2 project is a large multidisciplinary, multi-year research program on the Next Generation Attenuation (NGA) models for shallow crustal earthquakes in active tectonic regions. The research project has been coordinated by the Pacific Earthquake Engineering Research Center (PEER), with extensive technical interactions among many individuals and organizations. NGA-West2...
Authors
Yousef Bozorgnia, Norman A. Abrahamson, Linda Al Atik, Timothy D. Ancheta, Gail M. Atkinson, Jack W. Baker, Annemarie S. Baltay Sundstrom, David M. Boore, Kenneth W. Campbell, Brian S.J. Chiou, Robert B. Darragh, Steve Day, Jennifer Donahue, Robert W. Graves, Nick Gregor, Thomas C. Hanks, I. M. Idriss, Ronnie Kamai, Tadahiro Kishida, Albert Kottke, Stephen A. Mahin, Sanaz Rezaeian, Badie Rowshandel, Emel Seyhan, Shrey Shahi, Tom Shantz, Walter Silva, Paul A. Spudich, Jonathan P. Stewart, Jennie Watson-Lamprey, Kathryn Wooddell, Robert Youngs
Adding fling effects to processed ground‐motion time histories Adding fling effects to processed ground‐motion time histories
Fling is the engineering term for the effects of the permanent tectonic offset, caused by a rupturing fault in the recorded ground motions near the fault. It is expressed by a one‐sided pulse in ground velocity and a nonzero final displacement at the end of shaking. Standard processing of earthquake time histories removes some of the fling effects that may be required for engineering...
Authors
Ronnie Kamai, Norman A. Abrahamson, Robert Graves
Imaging P and S attenuation in the Sacramento-San Joaquin Delta region, northern California Imaging P and S attenuation in the Sacramento-San Joaquin Delta region, northern California
We obtain 3-D Qp and Qs models for the Delta region of the Sacramento and San Joaquin Rivers, a large fluvial-agricultural portion of the Great Valley located between the Sierra Nevada batholith and the San Francisco Bay - Coast Ranges region of active faulting. Path attenuation t* values have been obtained for P and S data from 124 distributed earthquakes, with a longer variable window...
Authors
Donna Eberhart-Phillips, Clifford Thurber, Jon Peter B. Fletcher
Geologic logs of geotechnical cores from the subsurface Sacramento-San Joaquin Delta, California Geologic logs of geotechnical cores from the subsurface Sacramento-San Joaquin Delta, California
This report presents and summarizes descriptive geologic logs of geotechnical cores collected from 2009–12 in the Sacramento–San Joaquin Delta, California, by the California Department of Water Resources. Graphic logs are presented for 1,785.7 ft of retained cores from 56 borehole sites throughout the Sacramento-San Joaquin Delta. Most core sections are from a depth of ~100–200 feet...
Authors
Katherine L. Maier, Daniel J. Ponti, John C. Tinsley, Emma Gatti, Mark Pagenkopp
High-frequency imaging of elastic contrast and contact area with implications for naturally observed changes in fault properties High-frequency imaging of elastic contrast and contact area with implications for naturally observed changes in fault properties
During localized slip of a laboratory fault we simultaneously measure the contact area and the dynamic fault normal elastic stiffness. One objective is to determine conditions where stiffness may be used to infer changes in area of contact during sliding on nontransparent fault surfaces. Slip speeds between 0.01 and 10 µm/s and normal stresses between 1 and 2.5 MPa were imposed during...
Authors
Kohei Nagata, Brian D. Kilgore, Nicholas M. Beeler, Masao Nakatani
Effects of 2010 Hurricane Earl amidst geologic evidence for greater overwash at Anegada, British Virgin Islands Effects of 2010 Hurricane Earl amidst geologic evidence for greater overwash at Anegada, British Virgin Islands
A post-hurricane survey of a Caribbean island affords comparisons with geologic evidence for greater overwash at the same place. This comparison, though of limited application to other places, helps calibrate coastal geology for assessment of earthquake and tsunami potential along the Antilles Subduction Zone. The surveyed island, Anegada, is 120 km south of the Puerto Rico Trench and is...
Authors
Brian F. Atwater, Zamara Fuentes, Robert B. Halley, Uri S. ten Brink, Martitia P. Tuttle
Paleoearthquakes at Frazier Mountain, California delimit extent and frequency of past San Andreas Fault ruptures along 1857 trace Paleoearthquakes at Frazier Mountain, California delimit extent and frequency of past San Andreas Fault ruptures along 1857 trace
Large earthquakes are infrequent along a single fault, and therefore historic, well-characterized earthquakes exert a strong influence on fault behavior models. This is true of the 1857 Fort Tejon earthquake (estimated M7.7–7.9) on the southern San Andreas Fault (SSAF), but an outstanding question is whether the 330 km long rupture was typical. New paleoseismic data for six to seven...
Authors
Katherine M. Scharer, Ray Weldon, Ashley Streig, Thomas Fumal
Seismic‐wave attenuation determined from tectonic tremor in multiple subduction zones Seismic‐wave attenuation determined from tectonic tremor in multiple subduction zones
Tectonic tremor provides a new source of observations that can be used to constrain the seismic attenuation parameter for ground‐motion prediction and hazard mapping. Traditionally, recorded earthquakes of magnitude ∼3–8 are used to develop ground‐motion prediction equations; however, typical earthquake records may be sparse in areas of high hazard. In this study, we constrain the...
Authors
Suguru Yabe, Annemarie S. Baltay Sundstrom, Satoshi Ide, Gregory C. Beroza
Deep permeability of the San Andreas Fault from San Andreas Fault Observatory at Depth (SAFOD) core samples Deep permeability of the San Andreas Fault from San Andreas Fault Observatory at Depth (SAFOD) core samples
The San Andreas Fault Observatory at Depth (SAFOD) scientific borehole near Parkfield, California crosses two actively creeping shear zones at a depth of 2.7 km. Core samples retrieved from these active strands consist of a foliated, Mg-clay-rich gouge containing porphyroclasts of serpentinite and sedimentary rock. The adjacent damage zone and country rocks are comprised of variably...
Authors
Carolyn A. Morrow, David A. Lockner, Diane E. Moore, Stephen H. Hickman
Continuous uplift near the seaward edge of the Prince William Sound megathrust: Middleton Island, Alaska Continuous uplift near the seaward edge of the Prince William Sound megathrust: Middleton Island, Alaska
Middleton Island, located at the seaward edge of the continental shelf 50 km from the base of the inner wall of the Aleutian Trench, affords an opportunity to make land-based measurements of uplift near the toe of the Prince William Sound megathrust, site of the 1964, M = 9.2, Alaska earthquake. Leveling surveys (1973–1993) on Middleton Island indicate roughly uniform tilting (~1 µrad/a...
Authors
James C. Savage, George Plafker, Jerry L. Svarc, Michael Lisowski
Implications of next generation attenuation ground motion prediction equations for site coefficients used in earthquake resistant design Implications of next generation attenuation ground motion prediction equations for site coefficients used in earthquake resistant design
Proposals are developed to update Tables 11.4-1 and 11.4-2 of Minimum Design Loads for Buildings and Other Structures published as American Society of Civil Engineers Structural Engineering Institute standard 7-10 (ASCE/SEI 7–10). The updates are mean next generation attenuation (NGA) site coefficients inferred directly from the four NGA ground motion prediction equations used to derive...
Authors
Roger D. Borcherdt
Arroyo channel head evolution in a flash-flood-dominated discontinuous ephemeral stream system Arroyo channel head evolution in a flash-flood-dominated discontinuous ephemeral stream system
We study whether arroyo channel head retreat in dryland discontinuous ephemeral streams is driven by surface runoff, seepage erosion, mass wasting, or some combination of these hydrogeomorphic processes. We monitored precipitation, overland flow, soil moisture, and headcut migration over several seasonal cycles at two adjacent rangeland channel heads in southern Arizona. Erosion occurred...
Authors
Stephen B. DeLong, Joel P. L. Johnson, Kelin X. Whipple