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Utilization of deep borehole : Challenges accompanying
the hot spring development and the earth science
Ryuji IKEDA
Graduate School of Science, Hokkaido University

Abstract
With the advance in drilling technology, it has become possible to obtain informationfrom the deep underground. However, drilling can only reach into the earth’s crust at
most +* km deep from the surface. That said, we can ascertain some phenomena andprocesses which are being generated, even if only in the shallow crust. By utilizing thedrilling technology for oil and gas, we can venture into unknown earth science problems
such as earthquake occurrence and volcano eruption mechanisms. Additionally, indispensable resources for life such as hot springs and geothermal energy can be extracted.
Here, the present state of hot spring drilling in Hokkaido is reviewed, and hot spring
depletion problems caused by deep drilling are considered. Also, the deep drilling
directly provides samples of rocks and ﬂuids that contain an abundance of informationfrom the earth’s deeper crust. Experiment and long-term observation in boreholes willlead to a better understanding of dynamic changes, which are progressing in the crust atpresent. The e#ectiveness of the deep scientiﬁc drilling promoted by the International
Continental Scientiﬁc Drilling Program (ICDP) is also described in order to clarify theproblems of earth science.
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Fig. + Trace the history of drilling depth for hot springs in Hokkaido (personalcommunication with the Geological Survey of Hokkaido, ,**/)

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