Strain Sensitivities and Noise Levels in Groundwater Levels at Observation Wells in and Around the Rupture Zone of the Future Tokai Earthquake

概要

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In order to identify anomalous changes in groundwater level quantitatively, we investigate noise levels of one, three and 24 hours' differences of groundwater levels in seven wells in and around the inferred rupture zone of the future Tokai earthquake. We estimate strain sensi tivities of the groundwater levels at seven wells from response of groundwater level to volu metric strain induced by earth tide. Finally we convert the noise levels of the groundwater levels into those in a unit of volumetric strain using the strain sensitivities of the groundwater levels. The strain-converted noise levels of 24 hours' difference in the groundwater level range from 3.8 × 10<SUP>-8</SUP> to 49 × 10<SUP>-8</SUP>. The minimum strain-converted noise level is almost the same as the noise level of volumetric strainmeters installed by Japan Meteorological Agency, and the maximum noise level is larger by a factor of five on the noise level of the volumetric strainmeters during the period with rainfall.
日本測地学会の論文