Acta Geodynamica et Geomaterialia

Title: PERMEABILITY ENHANCEMENT IN THE AQUIFER OF FUXIN WELL IN GEOTHERMAL AREA OF NORTHEASTERN CHINA INDUCED BY LOW-FREQUENCY TELESEISMIC WAVES OF THE 2011 MW 9.0 TOHOKU EARTHQUAKE
Authors: Zhang Yan, Fu Li-Yun, Huang Fuqiong and Chen Xuezhong
DOI: 10.13168/AGG.2015.0007
Journal: Acta Geodynamica et Geomaterialia, Vol. 12, No. 1 (177), Prague 2015
Full Text: PDF file (0.7 MB)
Keywords: permeability variation; teleseismic waves; Mw 9.0 Tohoku earthquake; coseismic water level changes; volume strain variation
Abstract: The Mw 9.0 Tohoku large earthquake induces far field (epicentral distance >1800 km) prominent coseismic water-level increase in the Fuxin well at northeastern China, which also influences volumetric strains. Different mechanisms of far-field coseismic water-level changes are analyzed by integrating these water-level/volume-strain data with broadband seismograms from a nearby station. Dilatation induced by propagating teleseismic wave (central frequency 0.02 Hz) may be the dominant mechanism of the observed water-level increases in the aquifer of Fuxin well. The dynamic energy density of ~5x10-2 J/m3 from the earthquake, (computed from broadband seismograms) could be large enough to incur the far-field dilatation stress of ~0.35 MPa (with the strain variation of -3.7935x10-6) in the aquifer. The resulting enhancement in permeability by the dilatation stress can build a new pore-pressure equilibrium between the Fuxin well and the nearby Sihe reservoir (~150 m away from the Fuxin well). The induced interstitial fluid flow in the region accounts for the sustained large-amplitude coseismic water-level increase. The Fuxin well lies in the geothermal area, and this study may also has some implications for the geothermal resource exploration.