Station Delays, Their Standard Deviations, and Event Relocations in the Reno-Area Basin from a Dense Deployment During the 2008 West Reno Earthquake Swarm

The Nevada Seismological Laboratory (NSL) conducted a citizen volunteer multiple-instrument temporary deployment using 90 USArray Flexible Array single-channel RefTek RT-125A (Texan) recorders. Stations were deployed at 106 locations in the Reno area basin during the May-July 2008 period of the 2008 west urban Reno-Mogul earthquake swarm (mainshock Mw 5.0). This was a very dense deployment as the basin only occupies about 150 square kilometers. The Flexible Array deployment supplemented recordings from 46 NSL/ANSS regional network and Reno-area strong-motion stations, plus 10 IRIS RAMP stations. ANSS strong-motion stations are distributed throughout the Reno basin, and IRIS RAMP instruments (broadband and accelerometer) were deployed in the near-source area. We have relocated 97 events in the West Reno/Mogul sequence from May-July 2008, using phase arrivals on all network and volunteer Texan stations. Hypoinverse runs showed that the dense station dataset improves event locations, leaving very small residuals, generally less than 0.5 sec. Event magnitudes varied from M0.19 to M3.05. Histograms of delays at each station show that the delays are relatively insensitive to the details of the Hypoinverse relocation process. HYPODD relocations show the detail of the local aftershock sequence of the largest event recorded during the Texan deployment, a M 3.05. We prepared an average station delay map, a mode-of-station-delay map, and a map of the standard deviations of the average station delays. We expect these delay maps will help in understanding the geometry of the Reno Basin.