Potential Earthquake Proxies from Remote Sensing Data

Abstract

At present, there is no clear scientific evidence of reliable earthquake precursors that can be used as an early warning system. However, many studies have also reported the existence of faint signatures that appear to be coupled to the occurrence of earthquakes. These anomalies have traditionally been detected using data from in-situ sensors near high-seismicity regions. On the other hand, remote sensors offer the potential of large spatial coverage and frequent revisit time, allowing the observation of remote areas such as deserts, mountains, polar caps, or the ocean. This chapter revises the state-of-the-art of the understanding of lithosphere–atmosphere–ionosphere coupling. It also presents recent studies by the authors’ ongoing investigation on short-to-midterm earthquake precursors. The Earth observation variables discussed are (1) surface temperature anomalies from thermal infrared or microwave radiometer measurements, (2) atmospheric signatures, (3) ionospheric total electron density fluctuations or scintillation measured from GNSS signals, and (4) other geophysical variables, including geomagnetic field fluctuations, changes in the Schumann resonance frequency, or low-frequency electromagnetic radiation. However, despite the seismic hazard risk models that exist and the results shown by these studies, it is still very difficult to predict the occurrence of earthquakes.