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Volcanologic investigations in the Commonwealth of the Northern Mariana Islands, September-October 1990 Volcanologic investigations in the Commonwealth of the Northern Mariana Islands, September-October 1990

U.S. Geological Survey volcanologists examined the ten volcanoes in the active Mariana Arc north of Saipan in May 1992, at the request of the Governor and the Disaster Control Office of the Commonwealth of the Northern Mariana Islands (CNMI). A shallow earthquake swarm on Anatahan in March-April 1990 and reports of possible new fuming on Agrigan in August 1990 had prompted the evacuation...
Authors
Richard B. Moore, R. Y. Koyanagi, M. K. Sako, F. A. Trusdell, George Kojima, R. L. Ellorda, S. K. Zane

Crustal structure of accreted terranes in southern Alaska, Chugach Mountains and Copper River Basin, from seismic refraction results Crustal structure of accreted terranes in southern Alaska, Chugach Mountains and Copper River Basin, from seismic refraction results

Seismic refraction data were collected along a 320-km-long "transect' line in southern Alaska, crossing the Prince William, Chugach, Peninsular, and Wrangellia terranes, and along several shorter lines within individual terranes. Velocity structure in the upper crust (less than 9-km depth) differs among the four terranes. In contrast, layers in the middle crust (9- to 25-km depth) in...
Authors
G. S. Fuis, E. L. Ambos, Walter D. Mooney, N.I. Christensen, E. Geist

Large landslides from oceanic volcanoes Large landslides from oceanic volcanoes

Large landslides are ubiquitous around the submarine flanks of Hawaiian volcanoes, and GLORIA has also revealed large landslides offshore from Tristan da Cunha and El Hierro. On both of the latter islands, steep flanks formerly attributed to tilting or marine erosion have been reinterpreted as landslide headwalls mantled by younger lava flows. These landslides occur in a wide range of...
Authors
R. T. Holcomb, R. C. Searle

A C language implementation of the SRO (Murdock) detector/analyzer A C language implementation of the SRO (Murdock) detector/analyzer

A signal detector and analyzer algorithm was described by Murdock and Hutt in 1983. The algorithm emulates the performance of a human interpreter of seismograms. It estimates the signal onset, the direction of onset (positive or negative), the quality of these determinations, the period and amplitude of the signal, and the background noise at the time of the signal. The algorithm has...
Authors
James N. Murdock, Scott E. Halbert
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