Publications

Landslides are common on inclined areas of the seafloor, particularly in environments where weak geologic materials such as rapidly deposited, finegrained sediment or fractured rock are subjected to strong environmental stresses such as earthquakes, large storm waves, and high internal pore pressures. Submarine landslides can involve huge amounts of material and can move great distances...

We elaborate on the well-known spatial association between axc volcanoes and Wadati Benioff zones and explore in detail their genetic relationships as dual physical expressions of slab metamorphism of the oceanic crust and uppermost mantle. At hypocentral depths less than 200 km intra slab Wadati-Benioff earthquakes tend to occur near the top surfaces of slabs. Subduction of very young...

Presents techniques that use only information contained within a raw, high-spectral-resolution, hyperspectral Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) scene to estimate and remove additive components (atmospheric scattering and instrument dark current). These techniques allow normalization of multiplicative components (instrument gain, topography, atmospheric transmission)...

No abstract available.

No abstract available.

Scientists with the U.S. Geological Survey have adapted their methods for quickly finding the exact source of an earthquake to the problem of locating gunshots. On the basis of this work, a private company is now testing an automated gunshot-locating system in a San Francisco Bay area community. This system allows police to rapidly pinpoint and respond to illegal gunfire, helping to...

No abstract available.

Hydrologic data were collected during 1987-93 as part of the U.S. Geological Survey's long-term Volcanic Hazards Monitoring Program of the Long Valley Caldera, Mono County, California. The data are presented in graphs or tables. Data collected for the Long Valley Hydrologic Advisory Committee monitoring program also are presented. Hydrologic data collected include continuous record of...

GLORIA images of the youngest channel on the Mississippi Fan indicate that it has not been a stable feature, but instead has shifted its course several times. A detailed study of a site of channel shifting found a complex stratigraphy that resulted from one episode of channel avulsion. The channel avulsion appears to have been initiated by a large mass flow that choked the channel below...

Reinterpretation of a voluminous regional ash-flow sheet (Masonic Park Tuff) as two separate tuff sheets of similar phenocryst-rich dacite erupted from separate source calderas has important implications for evolution of the multicyclic Platoro caldera complex and for caldera-forming processes generally. Masonic Park Tuff in central parts of the San Juan field, including the type area...

As a comparison to airborne infrared (IR) flux measurements, ground-based sampling of fumarole and soil gases was used to characterize the quiescent degassing of CO2 from Oldoinyo Lengai volcano. Aerial and ground-based measurements are in good agreement: ∼75% of the aerially measured CO2 flux at Lengai (0.05–0.06 × 1012 mol yr−1 or 6000–7200 tonnes CO2 d−1) can be attributed to seven...

Comparison of contemporaneous measurements of 84 distances in the range of 10 to 50 km by both Global Positioning System (GPS) and Geodolite (an electro-optical distance-measuring instrument) indicates that the Geodolite measurements are systematically longer by 0.283 ± 0.100 parts per million of the measured distance. Quoted uncertainty is 1 standard deviation. This amounts to 11.3 ± 4...