Natural Hazards and Earth System Sciences Tsunamigenic Ratio of the Pacific Ocean earthquakes and a proposal for a Tsunami Index

Abstract. The Pacific Ocean is the location where two-thirds of tsunamis have occurred, resulting in a great num-ber of casualties. Once information on an earthquake has been issued, it is important to understand if there is a tsunami generation risk in relation with a specific earthquake magni-tude or focal depth. This study proposes a Tsunamigenic Ratio (TR) that is defined as the ratio between the num-ber of earthquake-generated tsunamis and the total number of earthquakes. Earthquake and tsunami data used in this study were selected from a database containing tsunamigenic earthquakes from prior 1900 to 2011. The TR is calculated from earthquake events with a magnitude greater than 5.0, a focal depth shallower than 200 km and a sea depth less than 7 km. The results suggest that a great earthquake magnitude and a shallow focal depth have a high potential to generat