Seismic Swarm S20130211.1: Analysis of Activity Near Furnace Creek, California

Seismic swarm S20130211.1 was recorded beginning at 02:30 on 11 February 2013 and concluding at 00:38 on 13 February 2013. The sequence occurred 24 km east-northeast of Furnace Creek, California, and comprised 34 earthquakes over a period of 46 hours and 8 minutes. All events were of low magnitude, with the largest reaching 2.6, and hypocentral depths remained shallow, predominantly between 0 and 7 km.

The events clustered tightly in both time and space, characteristic of swarm behavior in which no single mainshock dominates. Magnitudes ranged from -0.3 to 2.6, and the majority of shocks registered below 1.0. Activity peaked on 11 February with 22 events, including the swarm’s strongest shock at 17:24:04 UTC. Subsequent days saw a rapid decline, with only 11 events on 12 February and a single event on 13 February that marked the swarm’s termination.

Furnace Creek lies within Death Valley National Park in eastern California, a region shaped by the interaction of the Pacific and North American plates. The area belongs to the Basin and Range province, where northwest-southeast extension produces north-south trending normal faults. The Death Valley fault system, including the Furnace Creek fault, accommodates a significant portion of this extension and has produced large surface-rupturing earthquakes in the Holocene. Ongoing dextral shear along the eastern California shear zone further contributes to the local strain field.

Historical records indicate that seismic swarms are uncommon in this immediate vicinity. Since 1 January 2000, only one prior swarm has been documented in the same source area, occurring in 2000. Background seismicity consists mainly of isolated, small-magnitude events distributed along the Furnace Creek and related faults. The 2013 swarm therefore represents a distinct departure from the typical pattern of solitary shocks.

Shallow focal depths observed during the swarm are consistent with the brittle upper crust in the Basin and Range, where temperatures allow frictional failure at depths less than 10–15 km. The absence of a clear mainshock-aftershock sequence and the rapid decay of activity suggest a transient triggering mechanism, possibly related to fluid migration or aseismic slip on nearby fault segments, although the precise driver remains undetermined from the available catalog data.

No damage or felt reports were associated with the swarm, reflecting both the low magnitudes and the remote location. The sequence nevertheless provides valuable data for refining seismic hazard models in the Death Valley region by illustrating the potential for clustered, low-magnitude activity along the Furnace Creek fault system.

References

United States Geological Survey Earthquake Catalog
California Geological Survey Fault Activity Map
Death Valley National Park Geologic Resources Inventory Report