The Nias cluster is named for island of Nias off the southwest coast of
North Sumatra, Indonesia. The selection of events went to ~150 km depth.
The cluster includes the 8.6 MW earthquake on March 28, 2005. It also
includes two events with magnitude >7, a 7.1 MS event on February 4,
1971 and a 7.8 MW event on April 6, 2010, and 20 earthquakes with
magnitudes between 6.0 and 6.9. Arrival time data from station SNSI on
Simeulue Island, GSI on Nias Island and PBSI on Tanahbala Island provide
unusually good azimuthal coverage for a subduction zone cluster. All
events have depth control from near-source and local-distance readings
and many events also have depth control from teleseismic depth phases.
