Publications

An M 6.7 intermediate-depth (66 km), in-slab earthquake occurring near the island of Kythera in Greece on 8 January 2006 was well recorded on networks of stations equipped with acceleration sensors and with broadband velocity sensors. All data were recorded digitally using recording instruments with resolutions ranging from almost 11 to 24 bits. We use data from these networks to study...

In two previous articles we presented a formulation for inferring the strains and rotations of the ground beneath a seismic array having a finite footprint. In this article we derive expressions for the error covariance matrices of the inferred strains and rotations, and we present software for the calculation of ground strains, rotations, and their variances from short baseline array...

A stick-slip event was induced in a cylindrical sample of Westerly granite containing a preexisting natural fault by loading at constant confining pressure of 150 MPa. Continuously recorded acoustic emission (AE) data and computer tomography (CT)-generated images of the fault plane were combined to provide a detailed examination of microscale processes operating on the fault. The dynamic...

Many investigators have applied the liquefaction potential index (LPI) to map regional liquefaction hazard. LPI, which integrates the liquefaction potential of susceptible soil elements at a specific location into a single value, has been used to assess both (1) spatial variability of liquefaction potential, and (2) liquefaction potential of surficial geologic units. A promising...

This report summarizes the discussions and information presented during the workshop on Aseismic Slip, Tremor, and Earthquakes. Workshop goals included improving coordination among those involved in conducting research related to these phenomena, assessing the implications for earthquake hazard assessment, and identifying ways to capitalize on the education and outreach opportunities...

We show clear evidence of non-volcanic tremor triggered by 2002 Mw7.8 Denali Fault earthquake near Parkfield. Triggered tremor is identified as bursts of high-frequency (∼2–8 Hz), non-impulsive seismic energy whose envelope is coherent among many stations and has the same periodicity as the passing surface waves. The tremor originates from at least three hypocenters near the San Andreas...

To better understand the structure of the San Andreas fault (SAF) at Burro Flats in southern California, we acquired a three-dimensional combined set of seismic reflection and refraction profiles centered on the main active trace at Burro Flats. In this article, we discuss the variation in shallow-depth velocities along each seismic profile, with special emphasis on the 1500 m/sec P-wave...

A key question in earthquake hazard analysis is whether individual faults within fault zones represent independent seismic sources. For the Seattle fault zone, an upper plate structure within the Cascadia convergent margin, evaluating seismic hazard requires understanding how north-side-up, bedding-plane reverse faults, which generate late Holocene fault scarps, interact with the north...

The U.S. / Japan Natural Resources (UJNR) Panel on Earthquake Research promotes advanced study toward a more fundamental understanding of the earthquake process and hazard estimation. The Panel promotes basic and applied research to improve our understanding of the causes and effects of earthquakes and to facilitate the transmission of research results to those who implement hazard...

The inventory of structures in heavily urbanized communities within the greater San Francisco (SF) Bay area that will experience strong ground motions from the rupture of the Hayward Fault includes a variety of types of recent and older structures built with a variety of materials and to different code standards. Those who remember the effects of the 1989 Loma Prieta earthquake on...

The U.S. Geological Survey has recently released a 2008 version of the probabilistic National Seismic Hazard Maps. These maps plot the peak ground acceleration (PGA) and spectral acceleration (SA) ordinates at 0.2 and 1.0 sec with 2% and 10% probabilities of being exceeded in 50 years, corresponding to earthquake return periods of about 2,475 and 475 years, respectively. These...

This Report introduces and summarizes the new Virtual Data Center (VDC) Tagged Format (VTF) Tool, which was developed by a diverse group of seismologists, earthquake engineers, and information technology professionals for internal use by the COSMOS VDC and other interested parties for the exchange, archiving, and analysis of earthquake strong-ground-motion data.