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Spatial variations in the frequency‐magnitude distribution of earthquakes at Soufriere Hills Volcano, Montserrat, West Indies
Author(s) -
Power John A.,
Wyss Max,
Latchman Joan L.
Publication year - 1998
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/98gl00430
Subject(s) - geology , impact crater , volcano , seismology , magnitude (astronomy) , radius , west indies , spatial distribution , ethnology , remote sensing , computer security , computer science , physics , astronomy , history
The frequency‐magnitude distribution of earthquakes measured by the b ‐value is determined as a function of space beneath Soufriere Hills Volcano, Montserrat, from data recorded between August 1, 1995 and March 31, 1996. A volume of anomalously high b ‐values ( b > 3.0) with a 1.5 km radius is imaged at depths of 0 and 1.5 km beneath English's Crater and Chance's Peak. This high b ‐value anomaly extends southwest to Gage's Soufriere. At depths greater than 2.5 km volumes of comparatively low b ‐values ( b ∼1) are found beneath St. George's Hill, Windy Hill, and below 2.5 km depth and to the south of English's Crater. We speculate the depth of high b ‐value anomalies under volcanoes may be a function of silica content, modified by some additional factors, with the most siliceous having these volumes that are highly fractured or contain high pore pressure at the shallowest depths.