Intraplate seismic hazard: Evidence for distributed strain and implications for seismic hazard - Intraplate Earthquakes - page 321

discussed earlier, late Holocene recurrence rates of large earthquakes have been estimated,
but it is not clear whether recent events are part of (relatively) short-term clusters that will
eventually end. For these regions there is a consensus if not a unanimous view that PSHA
treatments should assume that future rates will be comparable to those estimated for recent
millennia.
As pointed out by Stein and Newman ( 2004 ) , short catalogs can give rise to not only
apparent characteristic earthquakes with shorter recurrence rate than the long-term rate, but
also to earthquakes that appear less frequently than their long-term rates (“uncharacteristic
earthquakes.”) The possibility has been at least discussed, for example at the 2012 National
Seismic Hazard Mapping Program CEUS workshop, of including a low-weight branch in
a logic-tree approach corresponding to the possibility that no large (M > 7) earthquakes
will occur in the future in the NMSZ. One possible treatment of uncertainties associated
with the short historical catalog and limited geological record, then, would also include
logic-tree branches corresponding to the possibility that other source zones might produce
large earthquakes at a higher rate over the next few millennia than the rate observed during
the late Holocene.
Acknowledgments
I thank Pradeep Talwani for the invitation to contribute to this volume, as well as for
feedback on the chapter, and am grateful to Oliver Boyd, Rob Williams, and an anonymous
reviewer for critical reviews that improved the manuscript. I also acknowledge Karen Felzer
and Morgan Page for many helpful discussions.
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