Teleseismic observations from OSS IV
One of the primary objectives in placing seismic systems in deep-ocean boreholes is the detection of teleseismic earthquakes and nuclear events. If the oceanic basement is substantially quieter than the ocean floor and island sites, then the added data could yield information of considerable value in nuclear-test detection. This chapter presents and evaluates data relevant to this problem. The smallest teleseismic (Delta > 30/sup 0/) earthquake observed on the ocean sub-bottom seismometer (OSS) had a body-wave magnitude of 5.4. Only one nuclear explosion (m/sub b/ = 5.6) was clearly observed. With additional filtering and processing, nuclear explosions as small as m/sub b/ = 5.1 can be marginally observed. OSS records many regional earthquakes of the northwest circum-Pacific area that are not listed in the National Earthquake Information Service catalog. Teleseismic P-wave arrivals for several events contain frequencies as high as 8 Hz above the background noise. No teleseismic short-period S waves were seen, although high-frequency S waves from regional events were abundant. This dichotomy in the observability of S waves by OSS suggests that the lithosphere of the northwest Pacific has a high Q, but that the underlying asthenosphere is more highly attenuative.
- Research Organization:
- Hawaii Univ., Honolulu (USA). Hawaii Inst. of Geophysics
- OSTI ID:
- 5414254
- Report Number(s):
- AD-A-187530/1/XAB; HIG-Contrib-1669
- Resource Relation:
- Other Information: Pub. in Initial Reports of the Deep Sea Drilling Project, Vol. 88, 147-153(1987)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
58 GEOSCIENCES
EARTHQUAKES
SEISMIC DETECTION
NUCLEAR EXPLOSION DETECTION
BOREHOLES
ATTENUATION
BACKGROUND NOISE
BASEMENTS
ISLANDS
SEISMIC WAVES
CAVITIES
DETECTION
NOISE
SEISMIC EVENTS
450300* - Military Technology
Weaponry
& National Defense- Nuclear Explosion Detection
580201 - Geophysics- Seismology & Tectonics- (1980-1989)