Electromagnetic Precursors to the 2016 Kumamoto Earthquakes

• 作者: Alexander Schekotov Jun Izutsu Masashi Hayakawa Stelios Marcos Potirakis Tomokazu Asano
• 来源期刊: 地震研究(英文)
• 学科: 医学
• 关键词: ELECTROMAGNETIC Precursors The 2016 Kumamoto EARTHQUAKES ULF/ELF Radiation VLF Propagation ANOMALY ULF Depression
• 年，卷（期）: 2017,（4）
• 页码范围: 168-179
• 页数: 12页
• 分类号: R73

摘要

The Kumamoto area of Kyusyu Island was attacked by a series of large earthquakes (EQs) in April, 2016. The first two foreshocks had the magnitudes of 6.5 and 6.4, and about 1 day later there was the main shock on 15 April (UT) with magnitude 7.3. These are fault-type EQs, and so we would expect a variety of electromagnetic precursors to these EQs because we had detected different phenomena for the 1995 Kobe EQ, same fault-type EQ. As for the lithospheric effect, the ULF data at Kanoya observatory (about 150 km from the EQ epicenters) are used, but the simple statistical analysis could not provide us with any clear evidence of ULF radiation from the lithosphere. However, our conventional analyses indicated clear signatures in the atmosphere as ULF/ELF impulsive emissions and also in the ionosphere as observed by means of VLF propagation anomalies and ULF depression. ULF/ELF radiation appeared on 8-11 April (in UT) (maximum on 10 and 11 April (UT)), while ULF depression took place on 8 and 10 April (in UT), so that both atmospheric radiation and ionospheric perturbation took place nearly during the same time period.