Abstract
We analyze a set of precursory data measured before but compiled in retrospect of the MS7.5 Haicheng earthquake in February 1975 and the MS7.6–7.8 Tangshan earthquake in July 1976. We propose a robust and simple coarse-graining method that aggregates and counts how all the anomalies together (levelling, geomagnetism, soil resistivity, earth currents, gravity, earth stress, well water radon, well water level) develop as a function of time. We demonstrate strong evidence for the existence of an acceleration of the number of anomalies leading up to the major Haicheng and Tangshan earthquakes. In particular for the Tangshan earthquake, the frequency of occurrence of anomalies is found to be well described by the log-periodic power law singularity (LPPLS) model, previously proposed for the prediction of engineering failures and later adapted to the prediction of financial crashes. Using a mock real-time prediction experiment and simulation study, based on this methodology of monitoring accelerated rates of physical anomalies measured at the surface, we show the potential for an early warning system with a lead time of a few days.
Highlights
Background on the Tangshan EarthquakeIn the period 1966 to 1976, the Chinese engaged in the biggest earthquake monitoring program ever conceived
We provide some general background of the Tangshan earthquake, in particular explaining why it plays a special role in the history of seismicity, which is deeply intertwined with societal and political developments, and in the science of earthquake forecasting and predictions
Some of this data is published in graph form in post-mortem reports published after the Haicheng, Tangshan, and Songpan earthquakes [3,9,10], but accessing the raw data that lies under the charts is not straightforward
Summary
In the period 1966 to 1976, the Chinese engaged in the biggest earthquake monitoring program ever conceived. The style of the investigation is in the form of two case studies, which is complementary to the presently more prevalent approaches using a sufficient amount of high quality and reliable data enabling statistical testing In the latter style of scientific works, one requires the existence of similar data at the time of the earthquakes from other regions, and similar data from the epicentral regions at times when there were no earthquakes, to demonstrate that the alleged precursors only occur before large earthquakes and not at other places and/or times. The program engaged 35,000 amateur groups located in schools, factories, and public buildings, and a large and unique set of physical measurements of anomalies and human observations were acquired over the decade Some of this data is published in graph form in post-mortem reports published after the Haicheng, Tangshan, and Songpan earthquakes [3,9,10], but accessing the raw data that lies under the charts is not straightforward. The present work is more in the spirit of Johansen et al [23,24] of aggregating non-seismic data for testing the existence of earthquake precursors, but with a much larger set of physical variables to aggregate upon
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