Characteristics of coseismic water level changes at Tangshan well for the Wenchuan MS8.0 earthquake and its larger aftershocks

Abstract

Coseismic water level changes which may have been induced by the Wenchuan M S 8.0 earthquake and its 15 larger aftershocks (M S ≥5.4) have been observed at Tangshan well. We analyze the correlation between coseismic parameters (maximum amplitude, duration, coseismic step and the time when the coseismic reach its maximum amplitude) and earthquake parameters (magnitude, well-epicenter distance and depth), and then compare the time when the coseismic oscillation reaches its maximum amplitude with the seismogram from Douhe seismic station which is about 16.3 km away from Tangshan well. The analysis indicates that magnitude is the main factor influencing the induced coseismic water level changes, and that the well-epicenter distance and depth have less influence. M S magnitude has the strongest correlation with the coseismic water level changes comparing to M W and M L magnitudes. There exists strong correlation between the maximum amplitude, step size and the oscillation duration. The water level oscillation and step are both caused by dynamic strain sourcing from seismic waves. Most of the times when the oscillations reach their maximum amplitudes are between S and Rayleigh waves. The coseismic water level changes are due to the co-effect of seismic waves and hydro-geological environments.

Analysis of the Response Mechanism of Confined Aquifer Well Water Level System to Bulk Strain

“…This kind of step is more like a coseismic variation of the ground motion caused by seismic waves, or the residual performance of aquifer undergoing both the ground bulk strain and hydro-geological environmental change, or something like post-earthquake effect. In future, if the sampling rate could be upgraded to the standard of full spectrum seismograph, and the hydro-geological circumstance around the observation system was carefully taken into consideration, the coseismic response mechanism of well water level system would be much more intensively studied [33] .…”

Analysis of the co-seismic responses of the fluid well pattern system in Jiangsu Province to the Wenchuan and Tohoku earthquakes

“…In recent decade, the co-seismic effect phenomenon of national underground fluid observation wells caused by several large earthquakes has aroused the attention of many scholars, and has become a hot area of research. Many studies have been carried out on this phenomenon (Fu et al, 2007;Liu, 2003;Gao et al, 2006;Yang et al, 2007;Liao et al, 2008;Gu et al, 2010;Yin et al, 2009).…”