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Pavlis & Hamburger 1991
Pavlis, G.L. and Hamburger, M.W. (1991). Aftershock sequences of intermediate-depth earthquakes in the Pamir-Hindu Kush seismic zone. Journal of Geophysical Research 96: doi: 10.1029/91JB01510. issn: 0148-0227.

We examine the space-time seismicity patterns associated with the 40 largest (M≥5.6), intermediate-depth earthquakes that occurred in the Pamir-Hindu Kush zone between 1962 and 1984 to determine if an of these events were followed by aftershock sequences. To address this issue we examined data from the Soviet Central Asia regional earthquake catalog with two complementary techniques: (1) a subjective technique based on inspection of epicentral maps and (2) a quantitative method which assumed that the background seismicity was a Poisson process and which detected aftershocks as significant departures, as quantified by the Poisson model, from background rates. Of the 40 events we examined, only three were identified by both methods as having clearly defined aftershock sequences. These three events are also remarkably similar in several other ways: (1) they occurred at almost the same point in shape, (2) they have indistinguishable focal mechanisms, (3) they have similar magnitudes, and (4) they define two nearly equal time intervals (9.37 and 9.41 years). No other events in the Pamir-Hindu Kush zone exhibit comparable aftershock behavior. Six other events show rate anomalies, but the subjective method rated them negative or at least ambiguous. Four of these six we argue are caused by coincidental or man-made rate increases at the time of the mainshock. The remaining two are noteworthy because they are the two largest events to have occurred beneath the central Pamir. Each of these events shows a small, short burst of seismicity around the time period of the largest event in the sequence. We suggest two alternative hypotheses to explain our observations: (1) more events may have aftershock sequences, but the aftershocks are too small to be detected; or (2) the three events that had clear aftershocks are unique, and trigger a burst of aftershocks only because they have a special relationship to the most active nest of activity in the Hindu Kush zone. ¿American Geophysical Union 1991

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Abstract

Keywords
Seismology, Seismicity and seismotectonics, Seismology, Earthquake parameters, Tectonophysics, Plate boundary—general
Journal
Journal of Geophysical Research
http://www.agu.org/journals/jb/
Publisher
American Geophysical Union
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