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Abstract

Most tsunamis are generated by submarine earthquakes, and tsunami data are used to study earthquake sources. Tsunami waveform inversion was first proposed in the 1980s and has been applied to many earthquakes in the world. Tsunami speed is slower than typical rupture velocity of earthquake source, while seismic wave velocity is faster. This difference makes the tsunami waveform inversion more robust for spatial distribution, while the seismic inversion is more robust for temporal resolution. Global deployment of deep ocean bottom pressure gauges provides valuable data for tsunami waveform inversion, because they are free from coastal nonlinear effects. The effects of elastic earth on trans-oceanic tsunami propagation can now be accounted for. Tsunami data are also useful for historical and prehistorical earthquakes. Coastal tsunami heights or inundation limits can be estimated from damage descriptions in historical documents, often without information on temporal evolution of tsunami. For paleo-tsunamis, tsunami heights and inland extent can be estimated from the distribution of tsunami deposits. Thickness and grain size distribution of tsunami deposits are also sensitive to the tsunami source parameters, hence can be used to study earthquake sources, through sediment transport modeling. While nonlinear effects must be considered, these methods are also valuable tools to study earthquakes in the past.