Publications

The relationship between small-magnitude seismicity and large-scale crustal faulting along the Hayward Fault, California, is investigated using a double-difference (DD) earthquake location algorithm. We used the DD method to determine high-resolution hypocenter locations of the seismicity that occurred between 1967 and 1998. The DD technique incorporates catalog travel time data and...

A compilation of paleomagnetic data from volcanic deposits of Mount St. Helens is presented in this report. The database is used to determine signature paleomagnetic directions of products from its Holocene eruptive events, to assign sampled units to their proper eruptive period, and to begin the assembly of a much larger database of paleomagnetic directions from Holocene volcanic rocks...

The spectral-analysis-of-surface-waves (SASW) method is a relatively new in situ method for determining shear-wave slownesses. All measurements are made on the ground surface, making it much less costly than methods that require boreholes. The SASW method uses a number of active sources (ranging from a commercial Vibroseis truck to a small handheld hammer for the study conducted here)...

Based on the first arrival P and S data of 4 625 regional earthquakes recorded at 174 stations dispersed in the Yunnan and Sichuan Provinces, the 3-D velocity structure of crust and upper mantle in the region is determined, incorporating with previous deep geophysical data. In the upper crust, a positive anomaly velocity zone exists in the Sichuan basin, whereas a negative anomaly...

The aim of our work is to estimate the electromagnetic effects that can be detected in the submarine zones with hydrothermal activity. It is known that meso-scale flows appear in the regions over underwater volcanoes or hot rocks. Their origin is connected with heat flux and hot jets released from underwater volcanoes or faults in a sea bottom. Values of mean velocities and turbulent...

The Hayward fault, a major branch of the right-lateral San Andreas fault system, traverses the densely populated eastern San Francisco Bay region, California. We conducted a paleoseismic investigation to better understand the Hayward fault's past earthquake behavior. The site is near the south end of Tyson's Lagoon, a sag pond formed in a right step of the fault in Fremont. Because the...

No abstract available.

The Volcano Hazards Program of the U.S. Geological Survey (USGS) is part of the Geologic Hazards Assessments subactivity as funded by Congressional appropriation. Investigations are carried out in the Geology and Hydrology Disciplines of the USGS and with cooperators at the Alaska Division of Geological and Geophysical Surveys, University of Alaska Fairbanks Geophysical Institute...

Landslide inventory maps are generally prepared by interpreting the geomorphic expression of landsliding on aerial photos, topographic maps, or on the ground. Distinctive landslide geomorphology allows the recognition and mapping of landslides, although there are always landslides that have very subtle expression and are not identified. The difficulties of mapping landslides based on...

Blind field tests of the Field Integration Design and Operations (FIDO) prototype Mars rover were carried out 7-16 May 2000. A Core Operations Team (COT), sequestered at the Jet Propulsion Laboratory without knowledge of test site location, prepared command sequences and interpreted data acquired by the rover. Instrument sensors included a stereo panoramic camera, navigational and hazard...

Historic accretion of sediment on the Palos Verdes margin off Los Angeles County, CA, is dominated by two sources, effluent from Whites Point outfall and sediment eroded from the toe of Portuguese Bend landslide. In this paper, we document the recent history of sedimentation from these non-marine sources from 1937 until the late 1990s, and attempt to estimate the amount of material...

We infer the fine structure of a sub-Moho boundary layer (SMBL) at the top of the lithospheric mantle from high-resolution seismic observations of Peaceful Nuclear Explosions (PNE) on superlong-range profiles in Russia. Densely recorded seismograms permit recognition of previously unknown features of teleseismic propagation of the well known Pn and Sn phases, such as a band of incoherent