animals Article
Understanding Animal Detection of Precursor Earthquake Sounds Michael Garstang 1, * and Michael C. Kelley 2 1 2
*
Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22904, USA School of Electrical and Computer Engineering, Cornell University, Ithaca, NY 14853, USA;
[email protected] Correspondence:
[email protected]; Tel.: +1-434-979-3571
Received: 14 July 2017; Accepted: 28 August 2017; Published: 31 August 2017
Simple Summary: Scientists and amateur seismologists, particularly in China and Japan, have attempted over hundreds of years to use the behavior of both wild and domestic animals, disturbed by some sensory input well before a major earthquake, as a predictor of that event. The most striking case occurred in 1975, when, in addition to other precursor events, domestic and wild animals in and around the city of Haicheng, China behaved in an extremely anomalous fashion. The city was partially evacuated and many thousands of lives were saved. Re-analysis of these data, however, found it difficult to reconstruct the source, timing and impact of the actual earthquake warnings. Here we provide, for the first time, an explanation of how animals might detect, in advance, the occurrence of an earthquake and why inconsistencies are likely in such a prediction. Abstract: We use recent research to provide an explanation of how animals might detect earthquakes before they occur. While the intrinsic value of such warnings is immense, we show that the complexity of the process may result in inconsistent responses of animals to the possible precursor signal. Using the results of our research, we describe a logical but complex sequence of geophysical events triggered by precursor earthquake crustal movements that ultimately result in a sound signal detectable by animals. The sound heard by animals occurs only when metal or other surfaces (glass) respond to vibrations produced by electric currents induced by distortions of the earth’s electric fields caused by the crustal movements. A combination of existing measurement systems combined with more careful monitoring of animal response could nevertheless be of value, particularly in remote locations. Keywords: infrasound; electrophonics; sound detection; animal behavior; earthquake prediction
1. Introduction Attempts to use the behavior of wild and domestic animals, disturbed by some sensory input, to predict the occurrence of an earthquake, have a long history. Despite the many occasions when extreme adherent animal behavior has been observed, no consistent prediction of an earthquake, based upon animal behavior, has been reported [1,2]. No predictions of earthquakes have withstood careful scrutiny [3,4]. The magnitude 7.3, 4 February 1975, Haicheng, China, earthquake was considered to be the only major earthquake ever to have been predicted. Wang et al. [3], upon exhaustive reanalysis, found it difficult to determine the source, timing and impact of the actual earthquake warnings issued. In this paper, we present evidence that animals are capable of hearing a wide range of sounds, with frequencies ranging from ultra- to infrasound (kHz-Hz) and from biotic to abiotic sources. The sounds dealt with in this study are abiotic sounds not commonly considered within the biological acoustic literature [5,6]. Animals 2017, 7, 66; doi:10.3390/ani7090066
www.mdpi.com/journal/animals
Animals 2017, 7, 66
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We call upon our recent discoveries which describe sound signals, detectable by animals, that might serve as earthquake predictors [7,8]. Because of the use of sound made by elephants and the extensive literature documenting this behavior, we use elephants as the most appropriate vehicle to relate animal detection of sounds to events associated with, earthquakes. These deductions can then be credibly transferred to other animals, both domestic and wild, potentially detecting earthquakes. We acknowledge that our focus is upon the detection of sound by animals and not upon their response to other senses such as smell, taste and touch. Finally, we will evaluate these findings and address their contribution to earthquake prediction and the potential role that can be played by documenting animal response. 2. Previous Research 2.1. Animal Use of Sound Animals generate and detect sounds over a wide range of frequencies and for many purposes. Bats, for example, use ultra sound (20–200 kHz) to navigate and capture prey [9]. Elephants use infrasound (
