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Earthquake technology fights crime Earthquake technology fights crime

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...
Authors
John C. Lahr, Peter L. Ward, Peter H. Stauffer, James W. Hendley

Long-term geochemical surveillance of fumaroles at Showa-Shinzan dome, Usu volcano, Japan Long-term geochemical surveillance of fumaroles at Showa-Shinzan dome, Usu volcano, Japan

This study investigates 31 years of fumarole gas and condensate (trace elements) data from Showa-Shinzan, a dacitic dome-cryptodome complex that formed during the 1943-1945 eruption of Usu volcano. Forty-two gas samples were collected from the highest-temperature fumarole, named A-1, from 1954 (800??C) to 1985 (336??C), and from lower-temperature vents. Condensates were collected...
Authors
R.B. Symonds, Y. Mizutani, Paul H. Briggs

Database of potential sources for earthquakes larger than magnitude 6 in Northern California Database of potential sources for earthquakes larger than magnitude 6 in Northern California

The Northern California Earthquake Potential (NCEP) working group, composed of many contributors and reviewers in industry, academia and government, has pooled its collective expertise and knowledge of regional tectonics to identify potential sources of large earthquakes in northern California. We have created a map and database of active faults, both surficial and buried, that forms the...
Authors

Three-dimensional crustal structure of the southern Sierra Nevada from seismic fan profiles and gravity modeling Three-dimensional crustal structure of the southern Sierra Nevada from seismic fan profiles and gravity modeling

Traveltime data from the 1993 Southern Sierra Nevada Continental Dynamics seismic refraction experiment reveal low crustal velocities in the southern Sierra Nevada and Basin and Range province of California (6.0 to 6.6 km/s), as well as low upper mantle velocities (7.6 to 7.8 km/s). The crust thickens from southeast to northwest along the axis of the Sierra Nevada from 27 km in the...
Authors
M.M. Fliedner, S. Ruppert, P.E. Malin, S. K. Park, G. Jiracek, R. A. Phinney, J.B. Saleeby, B. Wernicke, R. Clayton, Rebecca Hylton Keller, K. Miller, C. Jones, J.H. Luetgert, Walter D. Mooney, H. Oliver, S.L. Klemperer, G. A. Thompson

Three-dimensional P and S wave velocity structure of Redoubt Volcano, Alaska Three-dimensional P and S wave velocity structure of Redoubt Volcano, Alaska

The three‐dimensional P and S wave structure of Redoubt Volcano, Alaska, and the underlying crust to depths of 7–8 km is determined from 6219 P wave and 4008 S wave first‐arrival times recorded by a 30‐station seismograph network deployed on and around the volcano. First‐arrival times are calculated using a finite‐difference technique, which allows for flexible parameterization of the...
Authors
H.M. Benz, B. A. Chouet, P.B. Dawson, J.C. Lahr, R.A. Page, J.A. Hole

Outburst floods from glacier-dammed lakes: The effect of mode of lake drainage on flood magnitude Outburst floods from glacier-dammed lakes: The effect of mode of lake drainage on flood magnitude

Published accounts of outburst floods from glacier‐dammed lakes show that a significant number of such floods are associated not with drainage through a tunnel incised into the basal ice—the process generally assumed—but rather with ice‐marginal drainage, mechanical failure of part of the ice dam, or both. Non‐tunnel floods are strongly correlated with formation of an ice dam by a...
Authors
Joseph S. Walder, John E. Costa

Waters associated with an active basaltic volcano, Kilauea, Hawaii: Variation in solute sources, 1973-1991 Waters associated with an active basaltic volcano, Kilauea, Hawaii: Variation in solute sources, 1973-1991

Chemical and isotopic analyses of samples collected from a December 1962-m-deep research borehole at the summit of Kilauea Volcano provide unique time-series data for composition of waters in the uppermost part of its hydrothermal system. These waters have a distinctive geochemical signature: a very low proportion of chloride relative to other anions compared with other Hawaiian waters...
Authors
R.I. Tilling, B.F. Jones

A catastrophic flood caused by drainage of a caldera lake at Aniakchak Volcano, Alaska, and implications for volcanic hazards assessment A catastrophic flood caused by drainage of a caldera lake at Aniakchak Volcano, Alaska, and implications for volcanic hazards assessment

Aniakchak caldera, located on the Alaska Peninsula of southwest Alaska, formerly contained a large lake (estimated volume 3.7 × 109 m3) that rapidly drained as a result of failure of the caldera rim sometime after ca. 3400 yr B.P. The peak discharge of the resulting flood was estimated using three methods: (1) flow-competence equations, (2) step-backwater modeling, and (3) a dam-break...
Authors
C. F. Waythomas, J. S. Walder, R. G. McGimsey, C.A. Neal
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