Rapid seismological quantification of source parameters of the 25 April 2015 Nepal earthquake

The 25 April 2015 Mw 7.9 Nepal earthquake is used to explore rapid seismological quantification methods to determine point-source parameters (seismic moment, focal mechanism, radiated energy, and source duration) and rupture directivity parameters (fault length and rupture velocity). Given real-time access to global seismic data, useful results can be obtained from W-phase, energy estimation, cut-and-paste, and backprojection analyses within 20-30 min of origin time or even faster if regional data were openly available (which is not the case at present for stations in China and India). This information can augment ground-shaking prediction procedures such as ShakeMap, which is currently provided by the U.S. Geological Survey National Earthquake Information Center. For such procedures to achieve their full potential, open access to calibrated high-quality ground-motion recordings at local, regional, and global stations is critical, and this should be embraced internationally.