<特別寄稿>単純に突進する --震源に向かって--

Abstract

On the occasion of my retirement, I summarized the main seismic observations I have been involved in. I started with the observation of micro-fractures in mines and progressed to the observation of very small earthquakes. Advances in electronic technology, especially the practical use of GPS satellites, made it possible to carry out long-term observations in mountainous areas without a power source, which had previously been impossible. In the Western Nagano Prefecture region, high-frequency seismic observations with 10 kHz sampling and trigger method were started in 1995 and continued until my retirement. From around 2008, a device named the “Manten System” was developed in collaboration with a group of small and medium-sized enterprises in the Kansai region. The Manten system can continuously record 250 Hz sampling for more than half a year using about 32 single dry cell batteries. They were deployed in western Nagano Prefecture, the central and northern Kinki region, the San-in earthquake zone and the northern part of the South Island of New Zealand, in collaboration with related research institutions. Some unexpected and remarkable earthquakes, such as the 2017 Kaikoura, New Zealand earthquake (Mw7.8), occurred in all of the above observation networks, and these observations provided important data on the process by which intraplate earthquakes are generated.