ABSTRACT
Conveners: Tomomasa Taniguchi (Rissho University, Japan)
Akinobu Miyakoshi (AIST, Japan) Akio Yamashita (Rakuno Gakuen University, Japan)
From Headwaters to the Ocean – Taniguchi et al. (eds) © 2009 Taylor & Francis Group, London, ISBN 978-0-415-47279-1
M. Yamano∗ & H. Hamamoto Earthquake Research Institute, University of Tokyo, Tokyo, Japan
S. Goto & A. Miyakoshi Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan
ABSTRACT: Long-term monitoring of temperature in boreholes has been conducted since 2000 in order to detect the propagation process of the ground surface temperature variation into subsurface and temporal change of the groundwater flow. Water temperature recorders with resolution of 1 mK were installed at multiple depths in the upper part of boreholes in East Asian countries. We found three different types of temperature variations: (1) diurnal and semidiurnal oscillations in phase with the water level change, corresponding to earth tides, (2) increases with nearly constant rates probably due to recent artificial change in the temperature condition at the ground surface, (3) short-period variations consisting of one-day and one-week components attributable to human activity.
