1. Department of Geology, Colorado College, 14 East Cache La Poudre Street, Colorado Springs, Colorado 80903 U.S.A., will.levandowski@tetratech.com
2. Now at TetraTech, Inc., 1100 South McCaslin Boulevard, Suite #150, Superior, Colorado, U.S.A.
3. Center for Earthquake Research and Information, The University of Memphis, Memphis, Tennessee 38152 U.S.A.