Yamauchi Hiroyuki, Hayakawa Masashi, Asano Tomokazu, Ohtani Nobuyo, Ohta Mitsuaki
Department of Animal Science and Biotechnology, Azabu University Graduate School of Veterinary Science, 1-17-71 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5201, Japan.
Hayakawa Institute of Seismo Electromagnetics Co. Ltd., UEC (University of Electro-Communications) Incubation Center, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan.
Animals (Basel). 2017 Mar 8;7(3):19. doi: 10.3390/ani7030019.
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.
先前的研究已经提供了关于地震前异常动物行为的定量数据；然而，很少有研究包含长期的观测数据。我们之前的研究表明，在一场极其强烈的地震发生前，奶牛的产奶量会下降。为了阐明产奶量在地震前是否会下降，我们研究了不同震级的地震与每日产奶量之间的关系。观测期为一年。结果显示，互相关分析表明，地震发生与大约三周前的产奶量之间存在显著的负相关。大约提前一周半，呈现出正相关，并且随着地震临近，这种相关性逐渐降至零。由于本研究仅考虑了十次地震，因此统计效力不强，需要未来使用更长观测期数据的研究。此外，我们将产奶量与表明电离层扰动的亚电离层甚低频/低频（VLF/LF）传播数据进行了比较。结果表明，在产奶量下降之后，所有地震之前VLF/LF传播数据都出现了异常；产奶量下降比传播异常更早。我们提到了极低频磁场是一种可能降低产奶量的刺激因素。这项研究表明，奶牛的产奶量在地震前会下降，并且它们可能对早于电离层扰动出现的刺激做出反应。
