Journal Article

Real-time discrimination of earthquake foreshocks and aftershocks

Wiemer, Stefan, Gulia, Laura

2019

Overview

Immediately after a large earthquake, the main question asked by the public and decision-makers is whether it was the mainshock or a foreshock to an even stronger event yet to come. So far, scientists can only offer empirical evidence from statistical compilations of past sequences, arguing that normally the aftershock sequence will decay gradually whereas the occurrence of a forthcoming larger event has a probability of a few per cent. Here we analyse the average size distribution of aftershocks of the recent Amatrice–Norcia and Kumamoto earthquake sequences, and we suggest that in many cases it may be possible to discriminate whether an ongoing sequence represents a decaying aftershock sequence or foreshocks to an upcoming large event. We propose a simple traffic light classification to assess in real time the level of concern about a subsequent larger event and test it against 58 sequences, achieving a classification accuracy of 95 per cent. Changes in the average size distribution of earthquakes are used to discriminate between foreshocks and aftershocks, and a traffic light classification is proposed for the real-time assessment of the probability of a subsequent larger event.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 704/2151/508 / 704/4111 / Aftershocks / Asthma / Classification / Comparative analysis / Decision making / Earthquake intensity / Earthquakes / Empirical analysis / Fault lines / Humanities and Social Sciences / Methods / multidisciplinary / Nutrition / Real time / Real-time data processing / Science / Science (multidisciplinary) / Seismic activity / Size distribution / Statistical analysis / Statistics / Technology application / Time discrimination / Time series / Traffic signals