Spatial Distribution of Energy in and around Taiwan

In present work, the earthquakes occurring between 1994 and 2018 are used to study the spatial distribution of energy in Taiwan. Maximum depth of earthquakes used in present work is 320 km. Huang (2012) approach based on local records from Taiwan is used to estimate energy for all earthquakes having M_L ≤ 6.4. As M_L saturates for higher magnitude earthquakes, a correction factor is applied to earthquakes above 6.4, based on energy calculation for Chi-Chi (September, 1999) and JiaSian (March, 2010) earthquakes. It is found that the distribution of earthquake number and energy is not uniform. In particular, 99% of the events occurred within 100 km while the remaining 1% occurred from 100 to 320 km. Most of the events, about 78% of the total earthquakes are confined to the upper 20 km depth. Around 90% of energy release in and around Taiwan is contributed by the earthquakes occurring till a depth of 100 km. Only a few earthquakes occur beyond 100 km depth; contributing around 10% of total released energy. Our results show that in addition to upper crust controlling plate-driving forces, the lower crust may also control these forces causing deformation.