Previous, Current, and Future Trends in Research into Earthquake Precursors in Geofluids

Abstract

Hazard reduction policies include seismic hazard maps based on probabilistic evaluations and the evaluation of geophysical parameters continuously recorded by instrumental networks. Over the past 25 centuries, a large amount of information about earthquake precursory phenomena has been recorded by scholars, scientific institutions, and civil defense agencies. In particular, hydrogeologic measurements and geochemical analyses have been performed in geofluids in search of possible and reliable earthquake precursors. Controlled experimental areas have been set up to investigate physical and chemical mechanisms originating possible preseismic precursory signals. The main test sites for such research are located in China, Iceland, Japan, the Russian Federation, Taiwan, and the USA. The present state of the art about the most relevant scientific achievements has been described. Future research trends and possible development paths have been identified and allow for possible improvements in policies oriented to seismic hazard reduction by geofluid monitoring.

On the Long Range Clustering of Global Seismicity and its Correlation With Solar Activity: A New Perspective for Earthquake Forecasting

“…Once the most appropriate mechanism will be precisely assessed for the solar-earthquake interactions, is could likely represent a powerful element to help in earthquake forecast. Actually, a large number of methods devoted to earthquake forecast have been implemented: an extensive review can be found, for example, in Martinelli (2020), as far as geofluid precursors are concerned. Among the most promising methods, anyway, there is the "pattern recognition" approach (Rotwain and Novikova, 1999;Kossobokov et al, 2002;Peresan et al, 2005).…”

Geological and Geophysical Factors Constraining the Occurrence of Earthquake Precursors in Geofluids: A Review and Reinterpretation

“…Rock permeability is in the range 10 −18 -10 −15 m at a depth of 10-20 km (Gleeson and Ingebritsen, 2017). These constraining parameters led Albarello (2015), Woith et al (2018) and Martinelli (2020) to propose that eventual precursory signals recorded in geofluids and as ground deformation may be considered as an indicator of the stress field evolution over time rather than signals generated by a hypothetical focal volume of a forthcoming seismic event.…”

Hydrogeochemistry and Precursory Anomalies in Thermal Springs of Fujian (Southeastern China) Associated with Earthquakes in the Taiwan Strait

“…So, the circulation system of underground fluids could be affected by the same tectonic stress field at the strong interplate seismic zone in eastern Taiwan, the marginal seismic zone in western Taiwan and the intraplate seismic zone along the southeast coast of Fujian. According to the research results, the strain radius of a M6 earthquake can reach 380 km [72], so it could cause fluid mixing, deep fluid upwelling and water-rock reaction intensification when a M ≥ 6 earthquake within a few hundred kilometers nearby occurs, which would lead to changes in the ion concentration in the thermal springs [73]. This may be one of the reasons why the ion concentration in some thermal springs changed significantly before the Hualien M6.1 earthquake.…”