A comprehensive study of the seismotectonics of the eastern Aleutian arc and associated volcanic systems: Technical progress report, April 1, 1984-March 31, 1987

Technical Report · Tue Jul 01 04:00:00 EDT 1986

OSTI ID:5404954

Jacob, K H; Taber, J; Boyd, T

Peculiar stress anomalies in the descending slab have been documented by composite focal mechanisms to be associated with the zone that in 1978-80 slipped aseismically at depth. The exact geometry of the descending slab has been delineated with the help of three-dimensional ray tracing. The detailed seismicity, tectonics and seismic potential of the Unalaska seismic gap have been reviewed. It is believed to be presently capable of a Mw approx. = 8.6 earthquake. A thorough analysis of the volcano seismicity of Pavlof volcano indicates a close correlation of seismic signals with periods prior and during eruptions, probably related to degassing of mobile magma in the upper 1.6 km of the volcanic vent. After some quiescence in 1985 Pavlof erupted vehemently in spring 1986 and is still active at present. A strong (10%) low-velocity anomaly in the crust beneath Pavlof volcano and Emmons caldera has been detected. Strong-motion data for most of Alaska, including those collected by the Shumagin accelerometer array have been analyzed and indicate high peak accelerations and large scatter. A thorough review of the seismic and volcanic hazards in the Gulf of Alaska has been completed. Research results for the period 1984 to 1986 were reported in 18 publications some of which are reproduced in this report. 26 refs.

• Research Organization: Columbia Univ., Palisades, NY (USA). Lamont-Doherty Geological Observatory
• DOE Contract Number: FG02-84ER13221
• OSTI ID: 5404954
• Report Number(s): DOE/ER/13221-2; ON: DE88005039
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580201* -- Geophysics-- Seismology & Tectonics-- (1980-1989)
ALASKA
ALEUTIAN ISLANDS
DOCUMENT TYPES
FEDERAL REGION X
FORECASTING
HISTORICAL ASPECTS
ISLANDS
MEASURING INSTRUMENTS
NORTH AMERICA
PLATE TECTONICS
PROGRESS REPORT
SEISMIC ARRAYS
SEISMIC EVENTS
SEISMICITY
STRESSES
SUBDUCTION ZONES
TECTONICS
USA
VOLCANISM