ETAS 2.x: The 2015 Nepal aftershock forecast, a Global ETAS Code, and ETAS based Ground Motion Forecastint

Mark R. Yoder, John M. Wilson, John B. Rundle, & Margaret T. Glasscoe

Published August 15, 2016, SCEC Contribution #6822, 2016 SCEC Annual Meeting Poster #303

In this work, we present improvements, extensions, and refinements to an ETAS type aftershock seismicity model, originally developed and published by Yoder et al. (2015, 2014 online). In our previous work, we show that near-field aftershock rate-densities can be accurately estimated based on well known earthquake scaling relations and geometric constraints. Of recent note, this model was used to produce the aftershock forecast that accurately predicted the locations of the m=7.3 and m=6.3 aftershocks following the 2015 m=7.8 Gorkha, Nepal mainshock event. Aftershock forecasts based on this model have also been posted for the large, m=7.8 event in Ecuador and the m=7 Kyushu, Japan earthquakes -- both in the Spring of 2016, as well as for several simulated disaster response exercises, including the FEMA 2016 "Cascadia Rising" scenario. In this work, we discuss the application of this model during the Nepal response, and we perform ensemble testing that shows that the model produces significant information gain and forecast skill. We have also developed an improved version of the code, which is freely available for use and collaborative development via GitHub. The new code is more streamlined and accessible to developers and practitioners. Perhaps more importantly, we have reorganized the workflow to enable parallel processing, and we have introduced a spatial indexing scheme that, by limiting the effective range of small earthquakes, facilitates very large, even global forecasts. We further extend the model by integrating it with ground motion prediction equations (GMPE). We invert the ETAS forecast to produce an array of source events, which we plug into standard point-source GMPE, to produce a map of expected threshold exceedance rates.

Key Words
earthquake, ETAS, GMPE, forecast, validation, predictability

Yoder, M. R., Wilson, J. M., Rundle, J. B., & Glasscoe, M. T. (2016, 08). ETAS 2.x: The 2015 Nepal aftershock forecast, a Global ETAS Code, and ETAS based Ground Motion Forecastint. Poster Presentation at 2016 SCEC Annual Meeting.

Related Projects & Working Groups
Earthquake Forecasting and Predictability (EFP)