Coseismic water level changes induced by two distant earthquakes in multiple wells of the Chinese mainland

• Published in: Tectonophysics Vol. 694; pp. 57 - 68
• Main Authors: Ma, Yuchuan, Huang, Fuqiong
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 02.01.2017; Elsevier BV
• Subjects: Artesian wells; Coseismic water level changes; Distant earthquakes; Duration; Earth; Earth tides; Earthquakes; Oscillations; Permeability; Seismic activity; Seismic energy density; Seismic response; Tidal energy; Tidal power; Tidal response; Tides; Water; Water levels; Water wells; Wells; Japan; Nepal; Coseismic water level changes; Distant earthquakes; Permeability; Seismic energy density; Tidal response
• ISSN: 0040-1951; 1879-3266
• DOI: 10.1016/j.tecto.2016.11.040

Coseismic water level oscillations, or step-like rises and step-like drops were recorded in 159 wells throughout the Chinese mainland due to the 2015 Nepal Mw 7.8 earthquake, and 184 wells for the 2011 Japan Mw 9.0 earthquake. The earthquake magnitude, and the associated dynamic stresses, has positive roles in both the sensitivity of water level to earthquake induced change, and the amplitude and duration of resulting coseismic water level changes. Wells whose water levels are sensitive to Earth tides have high potential to response to earthquakes. Polarities of step-like changes (rises or drops) are locally controlled and spatially variable, with artesian wells generally recording water-level rises. Permeability enhancement was assessed as a mechanism responsible for step-like changes by analyzing the tidal phase responses. Permeability variations are inferred for 17 out of 95 wells with step-like changes during the Nepal earthquake and for 32 out of 105 wells following the Japan earthquake; however, only 6 wells have permeability variations after both earthquakes. •Water level responses to far-field distal earthquakes in multiple wells are reported.•Dynamic stress and local hydrogeology have important role in water level responses.•Less than one third of wells with step-like changes have permeability variations.