We have engaged in broad-area regional monitoring for Mongolia and nearby regions, applying cross-correlation to long time windows for Lg-waves. For 2012 to 2016, using 4777 templates from a longer time-period, detections were made on searches of continuous data for a sparse network of IMS array stations, plus six long-running three-component open stations. Many candidate events were detected, for which there were too few stations in the detection network to perform locations. Fortunately a temporary PASSCAL network with many stations had been deployed in the region, which overlapped with the time period of our study. Adding windowed data from that network, based on expected arrival times for Lg-waves, we measured differential travel times to make location estimates. We have obtained pair-wise locations for 35,096 events in the detected catalog (4.7 million pairs of events). Location results are similar to those obtained in a previous study for all of China (Schaff et al, BSSA, June 2018) with average residuals of 0.0164 s; and 95% confidence ellipses with average 157 m semi-major axes. 93% of the pairs are less than 1 km apart. We are computing locations within large clusters of over 1000 events in several areas.
In addition to high-precision methods for locating events in an active seismic region, using continuous data from a sparse network, we have conducted large-scale searches for new seismic events. We have located them too, from open data, with quick searching methods.