Different hydraulic responses to the 2008 Wenchuan and 2011 Tohoku earthquakes in two adjacent far-field wells: the effect of shales on aquifer lithology

Earth, Planets and Space

Table 2 Amplitude and phase responses of the Zuojiazhuang and Baodi wells

Earthquake	Station	Pre-earthquake water-level amplitude response to M₂ wave/mm/nanostrain	Post-earthquake water-level amplitude response to M₂ wave/mm/nanostrain	Co-seismic change of water-level amplitude response to M₂ wave/mm/nanostrain	Background variability of water-level amplitude response to M₂ wave/mm/nanostrain	Pre-earthquake phase shift/°	Post-earthquake phase shift/°	Co-seismic phase-shift change/°	Background phase-shift variability/°
2008 M _W 7.9 Wenchuan	Zuojiazhuang	1.074	1.4748	0.4008	0.134	−29.9517	−9.6618	20.2899	8.0662
	Baodi	0.1494	0.1973	0.0479	0.0106	−5.7971	−9.1787	−3.3816	3.6399
2011 M _W 9.1 Tohoku	Zuojiazhuang	0.9453	1.4210	0.4757	0.0218	−41.5459	−4.8309	36.7150	1.3118
	Baodi	0.1747	0.2073	0.0327	0.0148	3.3816	−5.3140	−8.6957	3.7224

The pre-earthquake phase shifts and amplitude responses are single-point values obtained 15 days before the earthquake. The background phase and amplitude variability are the standard deviation of the phase shifts and amplitude responses before the earthquake for each well. The co-seismic changes were obtained by subtracting the pre-earthquake values from the single-point values after the earthquake