Project Abstract
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We will construct and test long- and short-term earthquake forecasts for CSEP (Collaboratory for the Study of Earthquake Predictability) natural labs including New Zealand, Japan, the Mediterranean area, and the whole globe. Our ultimate goal is to develop forecasting and testing methods to validate or falsify common assumptions regarding earthquake potential. Our immediate purpose is to extend the forecasts we made in 1999 for the northwest and southwest Pacific to include somewhat smaller earthquakes, adapt the methods to apply in other areas, and test the resulting forecasts against others. The previous forecasts used the CMT earthquake catalog (Ekstr¨om et al., 2005) to forecast magnitude 5.8 and larger earthquakes. Like our
previous forecasts, the new ones here are based on smoothed maps of past seismicity and assume spatial clustering. Our short-term forecasts also assume temporal clustering. We expand our forecast based on the CMT catalog to the whole world. The application of the present methodology to other subduction zones does not present any fundamental difficulty, and these subduction earthquakes constitute a major part of the global seismicity. So far we have relied on tensor focal mechanism solutions to forecast both the locations and focal mechanism of future earthquakes. We will continue to develop CMT-based forecasts for all natural labs, but we will also introduce a new approach that will circumvent the need for focal mechanisms. This permits use of earthquake catalogs that reliably report many smaller quakes but no such mechanism estimates. The result is that we can forecast earthquakes at higher spatial resolution and down to a magnitude threshold of 5.0 and perhaps as low as 4.7. The new forecasts can be tested much more quickly because smaller events are much more frequent. |
