Authors
Yasuhiro Yasuhiro
Kakioka Magnetic Observatory, Japan Meteorological Agency, Kakioka 595 Ishioka-shi, Ibaraki, Japan
Yoshitomo Ikoma
Kakioka Magnetic Observatory, Japan Meteorological Agency, Kakioka 595 Ishioka-shi, Ibaraki, Japan
Kenji Morinaga
Kakioka Magnetic Observatory, Japan Meteorological Agency, Kakioka 595 Ishioka-shi, Ibaraki, Japan
Junpei Shimizu
Matsushiro Seismological Observatory, Japan Meteorological Agency, Nishijo 3511, Matsushiro-machi,
Nagano-shi, Nagano, Japan
