Broad-scale applicability of correlation detectors to China seismicity

It is demonstrated that cross-correlation methods can successfully be applied on a large scale to the detection of seismic events arising in a variety of tectonic settings. The locations of about thousand earthquakes a year occurring in and near China are reported using phase picks from a large national network. We performed more than 100 million cross correlations on the waveforms of more than 18,800 events over 20 years, as recorded by a relatively sparse network; and detected about two thirds of the nationally reported events. Additional events (70% increase), beyond what standard processing detects for China on the sparse network, were also found. A corresponding reduction in detection threshold approaches 0.9 magnitude units for increasing station distance. As networks densify and archives grow, cross-correlation is likely to become more and more useful for purposes of maximizing the number of detected events and hence to improve knowledge of seismicity. Citation: Schaff, D. P. (2009), Broad-scale applicability of correlation detectors to China seismicity, Geophys. Res. Lett., 36, L11301, doi: 10.1029/2009GL038179.