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Comparison of Tidal Changes of Ground Strain and Groundwater Level Observed at Clustered Boreholes in Tono Region, Central Japan.

Accession number;01A0565404

Title;Comparison of Tidal Changes of Ground Strain and Groundwater Level Observed at Clustered Boreholes in Tono Region, Central Japan.

Author; ASAI Y (Assoc. Dev. Earthquake Prediction, Gifu, Jpn) AOKI H (Assoc. Dev. Earthquake Prediction, Gifu, Jpn) TANAKA T (Meijo Univ., Aichi, Jpn) KITAGAWA Y (Japan Nuclear Cycle Dev. Inst., Gifu, Jpn) AZUMA S (Japan Nuclear Cycle Dev. Inst., Gifu, Jpn)

Journal Title;Journal of the Geodetic Society of Japan

Journal Code:G0199A

ISSN:0038-0830

VOL.47;NO.1;PAGE.134-140(2001)

Figure&Table&Reference;

Pub. Country;Japan

Language;English

Abstract;In order to investigate the distortion of crustal movement observation in borehole, we carried out the tidal analysis of strain, tilt and groundwater level observed at clustered borehole sites and compared the results. We obtained the following preliminary results: (1) The comparison indicates that observed strains of the boreholes are 2.3 times larger than theoretically predicted strains at the maximum. (2) M2 phase of Areal strain change is approximately 2.5 degrees in advance of those of groundwater level change, but O1 phase of Areal strain is approximately 3.0 degrees behind those of ground water level change in TGR, and M2 and O1 phases of Areal strain change are approximately 28.1 and 2.3 degrees in advance of those of groundwater in 97FT-01. It is impossible to explain these phase shift using general models. (3) Groundwater level change in TGR and DH-2 agrees with each other within 1cm and 1 degree, respectively. Though we have no hydraulic information for TGR, we have that of DH-2. From the information, we concluded that the plane confined aquifers in the both sites will be in the same physical condition, namely, the same structure as DH-2 will affect the strain observations in TGR. A similar situation is also expected for 97FT-01. (author abst.)

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