A look at global seismicity during 1999 in the longer-term time frame |
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Authors: | Vasile Marza Juraci Carvalho Lucas Barros Cristiano Chimpliganond |
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Affiliation: | (1) Seismological Observatory, University of Brasilia, Brasilia, DF, Brazil;(2) Seismological Laboratory, National Institute (RD) for Earth Physics, Bucharest, Romania;(3) PrepComm/CTBTO, Vienna, Austria |
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Abstract: | An analysis and discussion of the main features and effects of the 1999global seismicity based especially on the inferred patterns of strong(Mw 7) earthquakes using NEIC/USGS data is presented.Based on the above data and their statistical features (see also Table 1)one may state that from the point of view of occurrence rate (number/yr)the 1999 global seismicity was fairly regular, but from the moment (orenergy) release standpoint it is well under the long-term average. The spacepartition was again rather typical and time distribution was quasi-Poissonian,noteworthy, the 1999 worldwide seismicity had an anomalously high deathtoll, to be discussed later. Two main new insights are brought by ouranalysis: (i) a (mega)quiescence along the whole south American segmentof circum-Pacific earthquake belt, which was inferred and rated asanomalous while it was underway and which, in retrospect, ended with thegreat (Mw = 8.4 HRV) 2001 Arequipa (Peru) event; (ii) an intriguingmonotonous rate decrease within only magnitude class 5.0 to 5.9 duringthe analyzed period (i.e., 1990–1999). |
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Keywords: | cumulative annualized rates earthquake fatalities large earthquakes seismicity seismic moment release |
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