Abstract Many methods for estimating site response compare ground motions at sites of interest to a nearby rock that is considered “reference” motion. The critical assumption in these the surface-rock-site record (reference) equivalent input motion base soil layers. Data collected this study show surface-rock can have their own, which could lead an underestimation seismic hazard when are used as reference sites. were from local and regional earthquakes on digital recorders, both surface...

Abstract During the months that followed 17 January 1994 M 6.7 Northridge, California, earthquake, portable digital seismic stations were deployed in San Fernando basin to record aftershock data and estimate site-amplification factors. This study analyzes data, recorded on 31 three-component stations, from 38 aftershocks ranging 3.0 5.1, depths 0.2 19 km. Site responses are estimated coda waves, S ratios of horizontal vertical (H/V) recordings. For site response is using both direct spectral...

Field observations suggest that preshaken natural sands in some seismic regions have high liquefaction resistance as a result of geologic aging and/or preshaking. This paper focuses on the young silty sand deposits located Imperial Valley California. Recent deposition and intense activity preshaking is main cause their increased resistance. The first part examines liquefiable layer at Wildlife site, which may been deposited by flooding approximately between 1905–1907. site was instrumented...

Abstract We analyze seismograms recorded by four arrays (B1–B4) with 100 m station spacing and apertures of 4–8 km that cross the surface rupture 2019 Mw 7.1 Ridgecrest earthquake. The extend from B1 in northwest to B4 southeast rupture. Delay times between P wave arrivals associated ∼1,200 local earthquakes teleseismic events are used estimate velocity variations beneath arrays. Both waves travel faster on northeast than southwest side fault B4, but contrast is less reliably resolved at B2...

Abstract Strong motion records of the 1989 Loma Prieta earthquake are inverted to determine a model rupture history. Uncorrected horizontal and vertical accelerograms integrated particle velocity time histories for 38 stations within an epicentral range 75 km. The bandpassed filtered with corners at 0.05 1.0 Hz. These using nonlinear method solve distribution slip amplitudes times specified locations on fault plane. plane is priori: km long 17 wide, extending from 3 19 depth constant dip...

Abstract We analyze the nonlinear and near‐surface geological effects of two Network for Earthquake Engineering Simulation at University California, Santa Barbara (NEES@UCSB) instrumented sites: Garner Valley Downhole Array (GVDA) Wildlife Liquefaction (WLA). The seismic interferometry by deconvolution method is applied to earthquake data recorded multisensor vertical array between January 2005 September 2013. Along cross section, local shear‐wave velocity extracted estimating travel time...

Research Article| March 01, 2013 Report on the August 2012 Brawley Earthquake Swarm in Imperial Valley, Southern California Egill Hauksson; Hauksson aCalifornia Institute of Technology, 1200 East Blvd., Pasadena, 91125 U.S.A.hauksson@caltech.edu Search for other works by this author on: GSW Google Scholar Joann Stock; Stock Roger Bilham; Bilham bUniversity Colorado, Department Geological Sciences, Campus Box 399, Boulder, Colorado 80309‐0399 U.S.A. Maren Boese; Boese Xiaowei Chen; Chen...

SUMMARY We derive a detailed earthquake catalogue and Vp, Vs Vp/Vs models for the region around 2019 Mw 6.4 Mw7.1 Ridgecrest, California, sequence using data recorded by rapid-response, densely deployed sensors following Ridgecrest main shock regional network. The new spans 4-month period, starting on 1 June 2019, it includes nearly 95 000 events detected located with iterative updates to our velocity models. final Vp correlate well surface geology in top 4 km of crust spatial seismicity...

This study determines site-response factors that can be applied as cor- rections to a rock-attenuation relationship for use in probabilistic seismic-hazard analysis. The are amplitude and site-class dependent. These amplification determined by averaging ratios between observed pre- dicted ground motions peak acceleration (PGA) 5% damped re- sponse spectral at 0.3, 1.0, 3.0 sec oscillator periods. observa- tions come from the strong-motion database of Southern California Earthquake Center...

Weak-motion geotechnical array recordings at 38 stations of the Japanese strong-motion network KiK-Net from 2003 M w 7:0 Miyagi-Oki aftershock sequence are used here to quantify amplification and attenuation effects nearsurface formations incident seismic motion.Initially, a waveform optimization algorithm is implemented for evaluation high-resolution, low-strain velocity (V s ), (Q density (ρ) profiles sites interest.Based on inversion results, V versus Q correlations developed, scattering...

Abstract Rapid seismic deployments following large earthquakes capture ephemeral near-field recordings of aftershocks and ambient noise that can provide valuable data for seismological studies. The U.S. Geological Survey installed 19 temporary stations the 4 July 2019 Mw 6.4 6 (UTC) 7.1 near city Ridgecrest, California. record aftershock sequence beginning two days after mainshock are expected to remain in field through approximately January 2020. deployment augments permanent network area...

The effects of near-surface soil stratigraphy on the amplitude and frequency content ground motion are accounted for in most modern U.S. seismic design codes building structures as a function conditions prevailing area interest.Nonetheless, currently employed site-classification criteria do not adequately describe nonlinearity susceptibility formations, which prohibits development standardized procedures computationally efficient integration nonlinear response analyses broadband...

Abstract Seismograms from ~700 local earthquakes recorded at various depths (0, 6, 15, 22, 50, and 150 m) by sensors of the Garner Valley Downhole Array in Southern California are used to analyze shallow velocity structure temporal changes seismic velocities after 2010 M7.2 El Mayor‐Cucapah (EMC) earthquake. The direct P S wave travel times between surface borehole stations reveal very low shear (178–259 m/s) high V p / s ratios (6.2) top 22 m. Temporal EMC earthquake estimated using...

Abstract The 2019 Ridgecrest, California, earthquake sequence included Mw 6.4 and 7.1 earthquakes that occurred on successive days beginning 4 July 2019. These two largest of the orthogonal faults ruptured Earth’s surface. To better evaluate 3D subsurface fault structure, (P- S-wave) velocity, temporal variations in seismicity, other important aspects sequence, we recorded aftershocks ambient noise using up to 461 three-component nodal seismographs for about months, one day after mainshock....

AbstractThe paper compares two liquefaction case histories in California: (1) the response of the Wildlife site Imperial Valley to 2010 El-Mayor Cucapah earthquake (Mw=7.2, amax=0.15  g)...

Ten Kinemetrics model SSA-2 Solid State Accelerographs were deployed in two dense arrays following the Landers-Big Bear earthquake sequence. The separated by approximately three km, first at a shallow alluvial soil site and second rock site. We examine sites terms of spectral ratio cross-spectrum estimates response. In order to construct an accurate representation motion horizontal plane, we treat components simultaneously as complex signal. Fourier transform this signal represents true...

Research Article| November 01, 2006 The COSMOS Virtual Data Center: A Web Portal for Strong Motion Dissemination Ralph J. Archuleta; Archuleta Institute Crustal Studies University of California, Santa Barbara 1140 Givertz Hall Barbara, California 93106-1100 ralph@crustal.ucsb.edu (R.J.A.) Search other works by this author on: GSW Google Scholar Jamison Steidl; Steidl Melinda Squibb Seismological Letters (2006) 77 (6): 651–658. https://doi.org/10.1785/gssrl.77.6.651 Article history first...

Abstract Subsurface structures play important roles in seismic ground motion, crustal hydrology, stability of the built environment, and more. Constraining temporal changes subsurface shear wave velocity ( V S ) can provide useful information to all these topics growing field hydrological monitoring with velocity. Using borehole records at Garner Valley, CA, we estimate seasonal variations from impulse response functions (IRFs) earthquake data (2005–2018) along IRFs cross‐correlation...

Abstract Erosion, hydrothermal activity, and magmatism at volcanoes can cause large unexpected mass wasting events. Large fluidized debris flows have occurred within the past 6000 yr Mount Adams, Washington, present a hazard to communities downstream. In August 2017, we began pilot experiment investigate potential of infrasound arrays for detecting tracking Adams. We deployed telemetered four-element array (BEAR, 85 m aperture), ~11 km from geologically unstable area where has repeatedly...

Automatic trip hammers have advantages for standard penetration test (SPT) of consistent drop height and low friction loss during hammer fall. These advantages, however, generate high energy transfer ratios (ER), typically about 90%. This efficiency causes lower sensitivity higher correction coefficients, CE. To reduce ER CE to increase the SPT conducted at Wildlife Liquefaction Array (WLA) Garner Valley Downhole Array, instrumented Network Earthquake Engineering Simulation sites, a...