Body wave and surface wave analysis of large and great earthquakes along the Eastern Aleutian arc, 1923-1993: Implications for future events

Journal Article · Fri Jun 10 04:00:00 EDT 1994 · Journal of Geophysical Research

DOI:https://doi.org/10.1029/93JB03124· OSTI ID:86732

Estabrook, C H ^[1]; Jacob, K H; Sykes, L R ^[2]

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1. GeoForschungszentrum, Potsdam (Germany)
2. Columbia Univ., Palisades, NY (United States)

The 500-km-long Alaska Peninsula and Shumagin Islands segments of the Aleutian arc have a moderate to high probability of rupturing in one or more large or great earthquakes in the next few decades. To understand the likely modes of rupture in the next sequence of large and great events and to delineate the current geometry of the plate interface, the authors determine focal mechanisms, depths, and source time functions from seismic records for the largest events since 1917: the great earthquake of November 10, 1938, and seven events with surface wave magnitude (M{sub s}) of 6.9 to 7.5. Teleseismic body waves and surface waves are used to estimate the seismic moments and gross rupture characteristics of the great earthquake of November 10, 1938, along the Alaska Peninsula. Body wave inversion of five P and four SH waves gives a duration of about 110 s in which moment was released in two episodes, each of about 50 s duration, with the second being larger than the first. The first source was located in the general vicinity of the epicenter of the mainshock, and the second, which occurred about 60 s later, was centered about 180 km to the northeast. The body-wave-derived seismic moment is 3.7 x 10{sup 21} N m (M{sub w} 8.3). Rupture in 1938 appears to have been confined to the Alaska Peninsula segment; uniform rupture into the Shumagin region is not supported by the data. The M{sub s} 6.9 earthquake of May 13, 1993, ruptured a small portion of the Shumagin gap. The earthquake of May 14, 1948, (M{sub s} 7.5) occurred on a shallow dipping thrust fault with a depth of about 31 km, not 60 km as originally suggested. Five M{sub s} {approximately}7 events in the 1938 rupture zone have locations, depths, and mechanisms that define a shallow dipping (16{degrees}-19{degrees}) plate interface which shallows to 8{degrees} under Kodiak Island. 85 refs., 15 figs., 2 tabs.

• DOE Contract Number: FG02-84ER13221
• OSTI ID: 86732
• Journal Information: Journal of Geophysical Research, Journal Name: Journal of Geophysical Research Journal Issue: B6 Vol. 99; ISSN JGREA2; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
ALEUTIAN ISLANDS
EARTHQUAKES
FORECASTING
PLATE TECTONICS
SEISMIC EVENTS
SEISMIC WAVES