1. Institute for Geophysics, University of Texas at Austin, 10100 Burnet Road, Austin, TX 78758, USA
2. Department of Geological Sciences, University of Texas at Austin, Austin, TX 78712, USA
3. Bureau of Economic Geology, University of Texas at Austin, 10100 Burnet Road, Austin, TX 78758, USA
4. Department of Civil and Environmental Engineering, Tufts University School of Engineering, 200 College Ave, Medford, MA 02155, USA