Twenty-Five Years of Progress in the Science of “Geological” Tsunamis Following the 1992 Nicaragua and Flores Events

We review a set of 47 tsunamis of geological origin (triggered by earthquakes, landslides or volcanoes) which have occurred over the past 25 years and provided significant new insight into theoretical, experimental, field, or societal aspects of tsunami science. Among the principal developments in our command of various aspects of tsunamis, we earmark the development of the W-phase inversion for the low-frequency moment tensor of the parent earthquake; the abandonment of the concept of a maximum earthquake magnitude for a given subduction zone, controlled by simple plate properties; the development and implementation of computer codes simulating the interaction of tsunamis with initially dry land at beaches, thus introducing a quantitative component to realistic tsunami warning procedures; and the recent in situ investigation of current velocities, in addition to the field of surface displacements, during the interaction of tsunamis with harbors. Continued research remains warranted, notably in the field of the real time identification of “tsunami earthquakes” whose tsunamis are larger than expected from their seismic magnitudes, especially conventional ones. The recent tragedy during the 2018 Krakatau flank collapse, along a scenario which had been quantitatively forecast, also emphasizes the need for a continued effort in the education of the populations at risk.