Imaging large earthquakes and plate boundary complexity with seismic big data
YoungHee Kim, Seoul National University
Earthquakes frequently claim countless lives and cause major damage to cities and infrastructures. Recent large (magnitude 8.8 in Chile, 2010; magnitude 9.0 in Japan, 2011) as well as moderate-size devastating events (magnitude 6.3 in New Zealand, 2010; magnitude 7.8 in Nepal, 2015; magnitude 6.4 in Taiwan, 2016) are forceful reminders that earthquakes cannot be predicted, and may hit at any time, at any place. However, we can prepare for the expected shaking levels and potential secondary effects (such as tsunamis) by investigating the physics of earthquake rupture, by studying seismic wave propagation in the Earth, and by finding innovative methods to quantify the seismic hazard.
Seismologists keep their ear on Earth’s internal systems, listening for signals from earthquake sources distributed around the globe. These seismic signals contain a wealth of information that reveals fault zone structures associated with dynamic processes that are active now or have been ongoing over multibillion years. Recent breakthroughs in theory and data processing allow every byte of continuous seismological data for imaging complexities of earthquake sources and structures throughout these dynamic systems, even extracting coherent signals from what had previously been dismissed as background noise. Continuous deployment of dense seismic instrument arrays on continents and also on the ocean floor provides critical observations for such active sources and structures, together with the in situ conditions and physical properties of the fault zone. The evolution of the fault zone materials under shear gives primary controls on spatial limits of great earthquake rupture and the manner in which slip may produce tsunamis. Understanding the nature of these transitions in physical properties of the fault zone and their relationship to earthquake rupture behavior is another important research task in seismology to lessen the seismic hazard.
In this presentation, I address key scientific frontiers involving Earth’s dynamic systems in two-folds: (1) monitoring the diversity of dynamical processes in earthquake sources, and (2) multi-scale imaging and modeling of Earth’s plate boundary systems.