Publication Date:
2014-10-04
Description:
Maximum earthquake magnitude ( m x ) is a critical parameter in seismic hazard and risk analysis. However, some recent large earthquakes have shown that most of the existing methods for estimating m x are inadequate. Moreover, m x itself is ill-defined because its meaning largely depends on the context, and it usually cannot be inferred using existing data without associating it with a time interval. In this study, we use probable maximum earthquake magnitude within a time period of interest, m p ( T ), to replace m x . The term m p ( T ) contains not only the information of magnitude limit but also the occurrence rate of the extreme events. We estimate m p ( T ) for circum-Pacific subduction zones using tapered Gutenberg–Richter (TGR) distributions. The estimation of the two TGR parameters, β -value and corner magnitude ( m c ), is performed using the maximum-likelihood method with the constraint from tectonic moment rate. To populate the TGR, the rates of smaller earthquakes are needed. We apply the Whole Earth model, a high-resolution global estimate of the rate of m ≥5 earthquakes, to estimate these rates. The uncertainties of m p ( T ) are calculated using Monte-Carlo simulation. Our results show that most of the circum-Pacific subduction zones can generate m ≥8.5 earthquakes over a 250-year interval, m ≥8.8 earthquakes over a 500-year interval, and m ≥9.0 earthquakes over a 10,000-year interval. For the Cascadia subduction zone, we include the 10,000-year paleoseismic record based on turbidite studies to supplement the limited instrumental earthquake data. Our results show that over a 500-year period, m ≥8.8 earthquakes are expected in this zone; over a 1000-year period, m ≥9.0 earthquakes are expected; and over a 10,000-year period, m ≥9.3 earthquakes are expected.
Print ISSN:
0037-1106
Electronic ISSN:
1943-3573
Topics:
Geosciences
,
Physics
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