M6.1 - SOUTH ISLAND OF NEW ZEALAND
Magnitude | 6.1 - Richter scale |
|---|---|
Depth | 5.9 km (3.7 miles) set by location program Km |
Location | SOUTH ISLAND OF NEW ZEALAND LAT -43.583, LON 172.68 |
Date-Time | Feb 21, 2011 23:51:42 UTC |
Source | USGS NEIC (WDCS-D) |
Event ID(s) | usb0001igm |
Distances from major cities | |
|---|---|
6 km (3 miles) SSE of Christchurch, New Zealand |
Tectonic Summary
Versión en Español
The February 21, 2011 South Island, New Zealand earthquake occurred as part of the aftershock sequence of the M 7.0 September 3, 2010 Darfield, NZ earthquake. The February 21st earthquake involved oblique-thrust faulting at the easternmost limit of previous aftershocks, and like the mainshock itself is broadly associated with regional plate boundary deformation as the Pacific and Australia plates interact in the central South Island, New Zealand.
This latest shock is significantly closer to the main population center of Christchurch, NZ, than is the September 2010 mainshock, in the vicinity of several other moderate (M 4 to 5) sized aftershocks located east of the main rupture zone of the 2010 event. There is no specific structure directly linking this event to the main fault of the 2010 mainshock, although there have been numerous aftershocks along generally east-west linear trends extending east from the end of the previous rupture. The north or north-east trends to the possible fault planes and the oblique thrust faulting mechanism as seen in the focal mechanism solution may reflect an association with similarly-trending faults previously mapped in the Port Hills region, just to the south of Christchurch.
Since the September 3, 2010 mainshock, there have been approximately 6 M>=5.0 aftershocks in the Christchurch region. The February 21st earthquake represents the largest aftershock to date, more that half a magnitude unit larger than the previous largest aftershock.
Earthquake Information for New Zealand
USGS Audio CoreCast Interview with Seismologist Rob Williams
Seismicity in the vicinity of Christchurch, New Zealand, following the September 3, 2010, M7.0, Darfield earthquake (yellow circles) and the February 21, 2011, M6.3, Christchurch earthquake (orange circles). Data from GNS Science, New Zealand.
Educational Slides for the Darfield, New Zealand Earthquake (09/03/2010) and its Aftershocks, Including the 02/21/2011 Christchurch Event (PPT version)
