Title: A
geomagnetic total intensity anomaly originated from lightning-induced
isothermal remanent magnetization: case of the Yatsugatake Magnetic
Observatory, central Japan
Source: EARTH
PLANETS AND SPACE 59 (3): 141-149 2007
Document Type: Article
Language: English
Abstract: Magnetic
total intensity anomaly maps of the Yatsugatake Magnetic Observatory,
central Japan, in 1975, 1982 and 2005 are examined. The magnetic
environment seems to be stable during this period except for the
appearance of an anomalous thin patch-pair in the middle part of the
observatory sometime between 1975 and 1982. The peak-to-peak amplitude
of the patch-pair is about 80 nT at 2 in above ground level. The
magnetization induced by the horizontal electric current in the ground
due to the lightning which hit the observatory area in July 1981 is a
probable cause for the patch-pair. Modeling confirmed that the
characteristics of the patch-pair are well reproduced by model
magnetizations that represent lightning-induced isothermal remanent
magnetization acquired from horizontal lightning electric current in
the ground. The required maximum magnetization to explain the
peak-to-peak amplitude of the patch-pair is estimated to be in the
range of 10 to 40 A/m.
Author Keywords: magnetic
anomaly map; lightning-induced isothermal remanent magnetization;
magnetic environment; total intensity
KeyWords Plus: CURRENTS
Addresses: Shimizu
H (reprint author), Univ Tokyo, Earthquake Res Inst, 7-3-1 Hongo, Tokyo
113, Japan
Univ Tokyo, Earthquake Res Inst, Tokyo 113,
Japan
Publisher: TERRA
SCIENTIFIC PUBL CO, 2003 SANSEI JIYUGAOKA HAIMU, 5-27-19 OKUSAWA,
SETAGAYA-KU, TOKYO, 158-0083, JAPAN
Subject Category: Geosciences,
Multidisciplinary
IDS Number: 155DT
ISSN: 1343-8832