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Aftershocks of an M = 4.2 earthquake in Hawaii and comparison with long-term studies of the same volume

Martha Kane Savage and Robert P. Meyer
Aftershocks of an M = 4.2 earthquake in Hawaii and comparison with long-term studies of the same volume
Bulletin of the Seismological Society of America (June 1985) 75 (3): 759-777

Abstract

Study of the aftershocks recorded in a 3-hr period after a 4.2 magnitude event on the East Rift Zone of Kilauea volcano, Hawaii, on 12 April 1982 shows that the aftershocks occurred on different planes than the main shock, probably as a result of stress redistribution; the aftershock locations are probably controlled by preexisting structures. This study also suggests that these relatively small aftershocks occurred in the same seismicity patterns as larger events recorded in the same volume over a period of 10 yr. Slips on most of the aftershocks and the main shock are in the same direction, perpendicular to the East Rift Zone, as has been found in studies of other, larger earthquakes. However, fault-plane solutions varied more, as did the tensional axes, and several of the smaller events showed movement in the opposite direction from the main shock and the rest of the aftershocks, suggesting some rebound was occurring near the edges of the aftershock zone. Because ten times as much energy was released in the aftershocks in a narrow linear region as elsewhere, and since the main shock epicenter was oceanward of all the aftershocks, we suggest that rupture began at the main shock hypocenter and propagated landward, implying an almost "one-dimensional" fault. For the aftershocks, the relationship between moment and magnitude was: log Mo = (1.18+0.17) M, + (17.3+0.17). Differences in amplification lead to site differences of up to 0.8 units in local magnitude and 1.5 orders of magnitude in energy release. These correlated somewhat with station time corrections in that the stations with the longest delay times also had greatest amplification.


ISSN: 0037-1106
EISSN: 1943-3573
Coden: BSSAAP
Serial Title: Bulletin of the Seismological Society of America
Serial Volume: 75
Serial Issue: 3
Title: Aftershocks of an M = 4.2 earthquake in Hawaii and comparison with long-term studies of the same volume
Affiliation: Univ. Wis. at Madison, Geophys. and Polar Res. Cent., Madison, WI, United States
Pages: 759-777
Published: 198506
Text Language: English
Publisher: Seismological Society of America, Berkeley, CA, United States
References: 30
Accession Number: 1985-064677
Categories: Seismology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables, sketch maps
N19°15'00" - N19°25'00", W155°19'60" - W155°04'60"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from U. S. Geological Survey, Hawaiian Volcano Observatory, , United States
Update Code: 1985
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