Statistical Evaluations of Variations in Dairy Cows' Milk Yields as a Precursor of Earthquakes.

Hiroyuki Yamauchi,Tomokazu Asano,Mitsuaki Ohta,Nobuyo Ohtani,Masashi Hayakawa

doi:10.3390/ani7030019

Abstract

Simple SummaryThere are many reports of abnormal changes occurring in various natural systems prior to earthquakes. Unusual animal behavior is one of these abnormalities; however, there are few objective indicators and to date, reliability has remained uncertain. We found that milk yields of dairy cows decreased prior to an earthquake in our previous case study. In this study, we examined the reliability of decreases in milk yields as a precursor for earthquakes using long-term observation data. In the results, milk yields decreased approximately three weeks before earthquakes. We have come to the conclusion that dairy cow milk yields have applicability as an objectively observable unusual animal behavior prior to earthquakes, and dairy cows respond to some physical or chemical precursors of earthquakes.Previous studies have provided quantitative data regarding unusual animal behavior prior to earthquakes; however, few studies include long-term, observational data. Our previous study revealed that the milk yields of dairy cows decreased prior to an extremely large earthquake. To clarify whether the milk yields decrease prior to earthquakes, we examined the relationship between earthquakes of various magnitudes and daily milk yields. The observation period was one year. In the results, cross-correlation analyses revealed a significant negative correlation between earthquake occurrence and milk yields approximately three weeks beforehand. Approximately a week and a half beforehand, a positive correlation was revealed, and the correlation gradually receded to zero as the day of the earthquake approached. Future studies that use data from a longer observation period are needed because this study only considered ten earthquakes and therefore does not have strong statistical power. Additionally, we compared the milk yields with the subionospheric very low frequency/low frequency (VLF/LF) propagation data indicating ionospheric perturbations. The results showed that anomalies of VLF/LF propagation data emerged prior to all of the earthquakes following decreases in milk yields; the milk yields decreased earlier than propagation anomalies. We mention how ultralow frequency magnetic fields are a stimulus that could reduce milk yields. This study suggests that dairy cow milk yields decrease prior to earthquakes, and that they might respond to stimuli emerging earlier than ionospheric perturbations.

Highlights

There have been numerous studies on precursors of earthquakes [1,2,3,4,5,6,7,8,9,10,11]
unusual animal behavior (UAB) accounted for approximately half of all reports of macroscopic anomalies identified in posteriori surveys, which included abnormal sounds, earthquake lights, earthquake clouds, ground deformation, and abnormalities in the ground water [17,18,19]
The data on milk yields used in the analyses followed a normal distribution and Factors affecting milk yields in dairy cows include ambient temperature and humidity as well as exhibited stationarity

Summary

Introduction

There have been numerous studies on precursors of earthquakes [1,2,3,4,5,6,7,8,9,10,11]. It has recently been reported that some precursors such as electromagnetic and radon anomalies showed statistical correlations with earthquakes [12,13,14,15,16]. As an example of quantitative UAB, changes in the locomotive activities of mice before large earthquakes were reported by Yokoi et al [20] and Li et al [21]. Grant et al [22] recently revealed, by the use of motion-triggered cameras, that wild animal activity in various species declined prior to the Contamana earthquake, with a magnitude (M) of 7.0. These reports were case studies for single large earthquakes

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Conclusion