1. Department of Civil Engineering, University of Southern California, Los Angeles, CA 90089, USA
2. Geology Department, University of Papua New Guinea, University PO, NCD [Port Moresby], Papua New Guinea
3. Department of Geological Sciences, Northwestern University, Evanston, IL 60208, USA
4. Earth Sciences Department, University of California, Santa Cruz, CA 95064, USA
5. British Geological Survey, Keyworth, Nottingham NG12 5GG, UK