Blanco Swarm, March 2010

An exceptionally large cluster of earthquakes occurring along the western Blanco Transform from 11-15 March 2010, within the East Blanco Depression. Figure 1 show the SOSUS locations and the USGS locations of the largest earthquakes in the sequence. The SOSUS locations are distributed along the transform, but generally are centered along the eastern side of the E. Blanco pull-apart basin. Also shown is a histogram of the number of earthquakes that were able to be counted from the hydrophone data, with 1126 events observed during the swarm. The location of these East Blanco events is ~50 km southwest of the intraplate swarm detected in 2008. The earthquake swarm in 1994 that lead to the mapping of pillow-lava mounds and barite chimneys was centered on the west side of this basin. The Ridge 2000 community was alerted to swarm but as of yet no response has occurred.

 

Map of Blanco swarm events
Figure 1: Location of March 11-15 earthquake swarm within East Blanco Depression of the Blanco Transform Fault. Red dots show earthquake locations derived using SOSUS, white stars are USGS locations of the largest events in the swarm. The M5.0 earthquake was relocated (white circle) using regional broadband arrays (courtesy of J. Braunmiller, OSU). The basin exhibits extensive, recent volcanism.
histogram of swarm events
2: Histogram of total earthquakes counted from SOSUS records.