Precursory Phenomena Prior to Earthquakes (2nd Edition)

Published Papers (1 paper)

In the present article, an attempt is made to gather, classify and evaluate the most known precursors, while an additional step ahead is the phrase of a preliminary proposal for their more effective utilization.

3. Title: Magnetic signatures of moderate magnitude earthquakes from ground observations, in distinct geological scenarios

Authors: Kusumita Arora, Rahul Prajapati and Archana R.K.

Abstract: All earthquakes are the result of stress accumulation in the Earth’s crust, culminating in slip along a weak zone, namely a fault. Each year approximately 500,000 earthquakes occur, detectable with current instrumentation. On land they lead to destruction of life and property, at sea they trigger tsunamis. Over a few hundred years, humans have put their minds to understanding the causes of earthquakes and the possibilities of predicting them. The complex interactions of multiple mechanisms, each of which may differ in their characteristics, have generally led to the conclusion that earthquakes cannot be predicted.

Data based studies of earthquake build up patterns span over at least last seven decades. The earlier studies were focussed on analysing signatures of very large earthquakes, which may have been recorded by instruments of opportunity. The pile up of literature on various aspects of such studies, although refuted individually in some cases, combined with highly improved instrumentation and network coverage of observations, make a strong case to continue to pursue the understanding of the physics of the preparatory phases of earthquakes and identify robust signatures in multiple physico-chemical parameters, which herald the occurrence of an earthquake.

In this work, we make a comparison of ground magnetic observations in the Andaman-Nicobar subduction zone, the Himalayan collision zone and the seismogenic zones of the Indian peninsular shield to make a comparative study of the pre-earthquake signatures.

4. Title: Developing the Concept of Earthquake Precursory Fingerprint

Author: Alexandru Szakács

Abstract: The concept of „precursory fingerprint” was proposed recently to characterize particular seismic structures capable of producing large-magnitude seismic events in order to establish a sound theoretical background of earthquake prediction research strategies and develop reliable prediction methodologies. It is a logical consequence of the commonsense statement that seismic structures are unique and their expecatble preshock behaviour is also unique. Therefore, earthquake prediction research efforts have to be focused on pointing out the unique precursory fingerprints of individual seismic structures instead of looking for universally valid precursors. Such a strategy might be conceptually based on 1) the principle of uniqueness of seismogenic structurers, 2) the principle of the integrated and interacting geospheres (lithosphere, hydrosphere, atmosphere, ionosphere, biosphere), and 3) the principle of non-equivalence of Earth surface spots in terms of signal receptivity.

The precursory fingerprint of a given seismic structure is a unique assemblege of percursory signals of various nature (seismic, physical, chemical, biological), detectable in principle using adequate monitoring equipment consisting of a matrix of n sensors emplaced on ground at „sensible” spots identified beforehand and on orbiting satellites. In principle, it is composed of a combination of signals emitted by „responsive sensors”, besides other „non-responsive sensors”, of the sensor matrix monitoring as many as possible virtual precursory processes by continuously measuring their relevant parameters. Each measured parameter has a pre-established (by experts) threshold value, and an uncertainty interval, discrimintaing between background and anomalous values, visualized similar to traffic light signals (green, yellow and red).

The precursory fingerprint can thus be envisaged as a particular configuration of „percursory signals” showing an unique and characteristic pattern having both space and time components. The „space component” of the precursory fingerprint is thought as a particular arrangement of the responsive signals on the master board of the monitoring system, which can be re-arranged, after a series of experiments, in a spontaneously understandable pattern. The „time component” is the characteristic time sequence of the appearing anomalous signals including order, occurrenec time before event, transition time between yellow and red signals, etc. Artificial Intelligence using pattern-recognition algorithms can be used to follow, evaluate and validate the precursory signal assemblage and, finally, to judge, together with an expert board of human operators, its „precursory fingerprint” relevance. Due to its particular charactersitics, the Vrancea seismic nest in Romania qualifies as an excellent experimental ground for earthquake prediction investigations based on the precursory fingerprint concept.

5. Title: Myths about Earthquakes: Quo vadis?

Authors: Vladimir KOSSOBOKOV and Anastasia NEKRASOVA