Spectral properties of Hawaiian microearthquakes: source, site, and attenuation effects

Thesis/Dissertation · Thu Jan 01 00:00:00 EST 1987

OSTI ID:6597281

Savage, M K

Shear-wave spectra were determined for 397 Hawaiian earthquakes located near Kilauea Caldera, and on its south flank, with moments (M/sub 0/) from 10/sup 17.4/ to 10/sup 20.8/ dyne-cm. An inversion of the spectra averaged the path effects, and separated the source spectra from the effects of site response relative to assumed good stations. Large variations in site response explain the station dependence of corner frequencies and magnitude that were seen in earlier studies. The theoretical spectra for the Brune source model, modified by an assumed spectral decay parameter related to near-surface attenuation, were examined. Previous investigators hypothesized that the south flank of Kilauea is moving away from the rest of the island along the old oceanic sediment layer. The author suggests that this layer is divided into a rupture zone defined by the earthquakes at depths of 9 km, and one or two slide zones that allow sliding but not fracture. The smaller, shallower earthquakes may result from stresses in the block above the rupture zone, caused by motion of the block away from the rest of the island. The author speculates that near the rift zones, the old sedimentary layer has been strengthened and made capable of fracture by intrusion of sills into the sediments, or by thermal or hydrothermal alteration of sediments, or both.

• Research Organization: Wisconsin Univ., Madison (USA)
• OSTI ID: 6597281
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CALDERAS
EARTHQUAKES
SEISMIC S WAVES
HAWAII
KILAUEA VOLCANO
RIFT ZONES
COASTAL REGIONS
LAYERS
SEDIMENTS
FEDERAL REGION IX
GEOLOGIC STRUCTURES
NORTH AMERICA
SEISMIC EVENTS
SEISMIC WAVES
USA
VOLCANOES
580201* - Geophysics- Seismology & Tectonics- (1980-1989)
580202 - Geophysics- Volcanology- (1980-1989)