Earthquake rupture forecasts provide vital estimates of the likelihood of future earthquakes in a region. However, Nissen et al. show that rupture forecasts can be muddied by not considering cascading multiple-fault ruptures. A combined geodetic and seismological reanalysis of a 1997 earthquake in Pakistan revealed dynamic triggering of a second fault 50 km away shortly after the first rupture. Current forecasts assume that triggering is limited to faults within 5 km. This observation suggests that longer-range, multiple-fault ruptures should be incorporated into forecasts, and it highlights the dangers resulting from this type of earthquake doublet.
Nat. Geosci. 10.1038/ngeo2653 (2016).