1. 1School of Earth Sciences, University of Bristol, Bristol, United Kingdom
2. 2Southern California Earthquake Center, University of Southern California, Los Angeles, California, U.S.A.
3. 3Now at, Nevada Seismological Laboratory, University of Nevada, Reno, Nevada, U.S.A.
4. 4GFZ German Research Centre for Geosciences, Potsdam, Germany
5. 5GNS Science, Lower Hutt, New Zealand
6. 6University of Naples Federico II, Naples, Italy