Collection of seismic data from aftershocks of the 4 September 2010 M7.1 Darfield Earthquake
Authors: Martha K Savage (VUW) with Euan Smith, Tim Stern John Townend (VUW) and Clifford Thurber, Ellen Syracuse (University of Wisconsin, Madison)
Paper number: 3767 (EQC 10/CE618)
Abstract
We deployed 14 seismometers within 50 km of the Greendale Fault following the Sept. 4 2010 magnitude 7.1 Darfield earthquake. These operated until mid-January 2011. The data have been archived at the Incorporated Research Institutions for Seismology (IRIS) data centre and at GNS Science. We used the data recorded by these instruments, supplemented by GeoNet broadband and strong-motion instruments, to study the changes in earthquake locations during the first four months of the aftershock sequence and the seismic anisotropy structure surrounding the fault. Earthquake relocations illuminate fault segments and show that the majority of aftershocks occurred beyond the areas of highest slip during the Darfield earthquake. Some of the earthquakes occurred on the fault that later broke in the February Christchurch earthquake. The lack of observable growth of seismicity along fault segments, suggests the Greendale Fault broke a pre-existing fault plane.
Technical Abstract
Following the Sept. 4 2010 Mw7.1 Darfield earthquake, with support from the Earthquake Commission and from the United States National Science Foundation, we deployed 4 broadband and 10 intermediate-period seismometers within 50 km of the Greendale Fault. These were operational until mid-January 2011. The data have been archived at the Incorporated Research Institutions for Seismology (IRIS) data center and at GNS Science. We used the data recorded by these instruments, supplemented by GeoNet broadband and strong-motion instruments, to study the spatio-temporal evolution of the first four months of the aftershock sequence and the seismic anisotropy structure surrounding the fault. Earthquake relocations illuminate fault segments and show that the majority of aftershocks occurred beyond the areas of highest slip during the Darfield earthquake. Some of the earthquakes occurred on the fault that later broke in the February Christchurch earthquake. Seismic anisotropy shows a mixture of fast directions parallel to the maximum horizontal stress and fault-parallel fast directions. This, combined with the lack of observable growth of seismicity along fault segments, suggests the Greendale Fault broke a pre-existing fault plane.
Order a research paper
Many of these research papers have PDF downloads available on the site.
If you'd like to access a paper that doesn't have a download, get in touch to ask for a copy.