Seismic Swarm S20000909.1: Analysis of Activity Near Beatty, Nevada
Seismic swarm S20000909.1 occurred 45 km east-southeast of Beatty, Nevada, beginning at 10:25 on 9 September 2000 and concluding at 22:59 on 14 September 2000. Over 132 hours and 33 minutes, the sequence produced 111 earthquakes. The first 100 events, recorded between 9 and 13 September, exhibited magnitudes predominantly between -0.9 and 2.8, with the majority falling below 0.5. Depths clustered tightly between 6 km and 9 km, indicating a shallow crustal source consistent with regional extensional faulting.
The sequence initiated with a magnitude -0.3 event at 6 km depth. A magnitude 2.8 shock at 8 km depth followed approximately nine hours later, marking the largest event. Subsequent activity consisted of numerous microearthquakes, with magnitudes rarely exceeding 0.5 after the initial day. Depth distribution remained stable, showing no systematic migration, which suggests repeated slip on a localized fault segment rather than fluid-driven propagation.
The Beatty region lies in the southern Basin and Range Province of Nevada, an area shaped by Cenozoic extension that produced north-trending normal faults and horst-graben topography. This tectonic setting accommodates ongoing east-west crustal stretching at rates of several millimeters per year. Historical records document moderate earthquakes along nearby structures such as the Death Valley fault system, with the province experiencing recurrent seismic swarms tied to fault interaction and minor volcanic features.
Since 1 January 2000, two swarms have been documented in the area, with S20000909.1 representing the first. The shallow focal depths and low-magnitude character align with background seismicity patterns observed across southern Nevada, where small events frequently cluster without producing surface rupture.
References
- U.S. Geological Survey Earthquake Catalog
- Nevada Seismological Laboratory Regional Seismicity Reports
- Basin and Range Province tectonic summaries from the Nevada Bureau of Mines and Geology