Looking for Earthquake Precursors From Space: A Critical Review

Abstract

Starting from late seventies, many observations have been reported about observations in space of signals reconciled with earthquakes and claimed as possible preseismic measurements. The detected parameters range from electromagnetic field components (in a large band of frequencies) to plasmas parameters; from particles detection to thermal anomalies; etc. Up to the DEMETER mission, the analyses have been carried out on datasets gathered by not devoted satellites. Even beyond the results obtained, the DEMETER mission has constituted a milestone for space-based investigations of seismo-associated phenomena drawing a baseline for next missions with respect instruments, observational strategy and measurements uncertainty. Nowadays, the CSES-01 satellite – developed within a sino-italian collaboration with the participation also of Austrian Institutes – represents the most advanced mission for investigating near-Earth electromagnetic environment aimed at extending the observation of earthquake precursors to a long time series. The benefit of the mission is even higher by considering that CSES-01 is the first of a program of several LEO small satellites, the second of which will be launched on 2023 with the same instruments and orbit of CSES-01, but with a shift of half of an orbit in order to monitor each trace twice per orbit. The article gives a short survey of space-based observations of preseismic phenomena from the early studies up to the more recent ones, critically reviewing results, hypotheses and trends in this research field. The supposed physical processes proposed to explain the observations are still unable to explain the large variety of the phenomenology, the statistical significance of the results are highly debated, and more in general a common consensus is still missing. Anyway, the investigation of the seismo-associated phenomena from space is a challenge for near future Earth observation.

A Critical Review of Ground Based Observations of Earthquake Precursors

“…As mentioned above, beyond the mechanical oscillations (of the ground surface or of the atmospheric layers), the geochemical fluids variations and the thermal anomalies, the list of proposed earthquake-precursors on ground includes many observations of electromagnetic disturbances. We will concentrate only on measurements on ground, addressing to the companion article by Picozza et al (2021) on the same volume for a review of the space born detection of possible seismo-electromagnetic precursors.…”

“…for a joint analysis of such complex and interrelated system (Ouzounov et al, 2018). Because data needed for these investigations are collected both on ground and by satellite, we address the reader to the companion article Picozza et al (2021) and to therein references, where this topic is further discussed for space-based observations of precursors. The possible correlation between seismic events and fluctuation of water column content has been studied for example by Dey et al (2004) for the 2001 M7.8 Gujarat earthquake; by Ma et al (2010) for the Hengchun (Taiwan) M 7.2 event of 2006 and by Wu et al (2016) for the 2009 M6.2 L'Aquila earthquake.…”

“…We will also summarize some of the physical models proposed to reconcile the observed phenomenology with the physics of earthquake even though a scientific consensus of which could be preferable is still missing. We address the reader to the paper (Picozza et al, 2021) published in this same issue that provides a review of satellite-based observations and more in general of earthquake precursors in space.…”

Worldwide Statistical Correlation of Eight Years of Swarm Satellite Data with M5.5+ Earthquakes: New Hints about the Preseismic Phenomena from Space

“…In this paper, we will deal with the delicate research on the possible precursors of earthquakes, i.e., those anomalous phenomena that might appear before earthquakes because they are caused by their preparation phase and thus anticipate their imminent occurrence. The earthquake precursors could be simply classified as seismic precursors and non-seismic precursors: the former are eventual modifications of seismicity or seismological parameters before the occurrence of an earthquake, while the latter, the object of our present research, are alterations of some geophysical parameters, such as atmospheric chemical and physical characteristics, radon emission, and, furthermore, possible electromagnetic disturbances up to the ionosphere [1][2][3]. Historically, some evidence of electromagnetic precursors has been reported in the data from ground magnetic observatories-for example, before the M6.9 Spitak (Armenia) 1988 and M7.1 Loma-Prieta 1989 earthquakes by Fraser-Smith et al [4] and Molchanov et al [5].…”

Multi-Parameter Observations of Seismogenic Phenomena Related to the Tokyo Earthquake (M = 5.9) on 7 October 2021

“…Finally, we summarize what is happening in the upper ionosphere, such as the F region of the ionosphere [82,83]. Our extensive analyses both on the TEC and ionosonde observational data have indicated that no clear anomalies are detected during the last phase of EQ preparation, unlike the situation in the lower ionosphere.…”