Source Analysis of the Crandall Canyon, Utah, Mine Collapse
Douglas S. Dreger,1*
Sean R. Ford,1,2
William R. Walter2
Analysis of seismograms from a magnitude 3.9 seismic event on
6 August 2007 in central Utah reveals an anomalous radiation
pattern that is contrary to that expected for a tectonic earthquake
and which is dominated by an implosive component. The results
show that the seismic event is best modeled as a shallow underground
collapse. Interestingly, large transverse surface waves require
a smaller additional noncollapse source component that might
represent either faulting in the rocks above the mine workings
or deformation of the medium surrounding the mine. Seismic moment
tensor results for nuclear explosions, explosion and other mining
cavity collapses, and tectonic earthquakes are compared, and
the separation of the different populations indicates that the
seismic moment tensor may be used for source-type discrimination.
2 Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.
* To whom correspondence should be addressed. E-mail: dreger{at}seismo.berkeley.edu
