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Characteristics of earth potential difference generated by seismic waves
Author(s) -
Takeuchi Nobunao,
Chubachi Noriyoshi,
Narita Ken'ichi
Publication year - 1997
Publication title -
electrical engineering in japan
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.136
H-Index - 28
eISSN - 1520-6416
pISSN - 0424-7760
DOI - 10.1002/(sici)1520-6416(19970415)119:1<74::aid-eej9>3.0.co;2-g
Subject(s) - seismometer , geology , seismology , potential difference , observatory , earth (classical element) , magnitude (astronomy) , seismic wave , intensity (physics) , geophysics , geodesy , physics , optics , electrode , quantum mechanics , astronomy , astrophysics , mathematical physics
To clarify the relationship between earthquakes and electrical phenomena, the earth potential difference has been observed continuously at Aobayama in Sendai and at Tsukidate, 60 km north of Sendai. A modified method for measuring this difference is used to reduce extraneous signals induced by artificial and natural earth current sources so that we were able to isolate these variation signals induced by seismic waves. We can clearly observe earth potential difference signals for all earthquakes of intensity more than 1 on the Japan Meteorological Agency scale. The P‐wave arrival times agree quite well with those of the seismographs obtained at the Sendai Meteorological Observatory. The signals of the Kobe earthquake, though less than 1 on the intensity scale in Sendai and Tsukidate, were clearly recorded at the sites of both observatories. The earth potential difference signals are also observed at three different underground positions. We found two interesting electric field characteristics caused by seismic waves: (1) the earth electrical field is one order of magnitude stronger in the vertical direction than in the horizontal direction and (2) this field increases rapidly with proximity to the ground surface. © 1997 Scripta Technica, Inc. Electr Eng Jpn 119(1): 74–81, 1997