Detection of groundwater flux changes in response to two large earthquakes using long-term bedrock temperature time series

JOURNAL OF HYDROLOGY

卷:590

Article

Liu, Qiongying¹  Chen, Shunyun¹  Chen, Lichun^1,2  Liu, Peixun¹  Yang, Zhuzhuan³  Lu, Lili¹ 

[1] China Earthquake Adm, State Key Lab Earthquake Dynam, Inst Geol, Beijing 100029, Peoples R China

[2] Guilin Univ Technol, Guilin 541006, Peoples R China

[3] China Earthquake Adm, Key Lab Act Tecton & Volcano, Inst Geol, Beijing 100029, Peoples R China

关键词: In-situ temperature measurement;    Eastern margin of the Tibetan Plateau;    Heat as a tracer;    Hydrological response to earthquake;    Near-field;    Fault zone;   

DOI  :  10.1016/j.jhydrol.2020.125245

来源: Elsevier

【 摘 要 】

Heat as a groundwater tracer has potential application in identifying earthquake-induced changes in fluid flow. Since convective heat transport modifies the phase and amplitude of periodic oscillations under pure heat conduction condition, temporal variation of groundwater flux can thus be derived from mull-depth periodic temperature signals. Here we present groundwater flux changes after two large earthquakes nearby, determined from in situ bedrock temperature measurements in the Xianshuihe fault zone, at the eastern margin of the Tibetan Plateau. Five-year temperature time series at six different locations are recorded by high sensitivity temperature sensors (10(-4) K) installed at various depths ranging from 0 to 20 m. Groundwater fluxes are estimated through time-varying amplitudes and phases of the annual oscillations, extracted from the Dynamic Harmonic Regression technique. Results show different hydrological responses to these two earthquakes. After the 2013 M-s 7.0 Lushan earthquake, sustained rise in upward flux was revealed at all locations in the intermediate-field, contradicting to the modeled coseismic static dilatational strains. However, groundwater flux patterns after the 2014 M-s 6.3 Kangding earthquake are consistent with the coseismic volumetric strain distribution of a quadrantal pattern of this event. We propose that enhanced hydraulic permeability by dynamic stress might cause the increased upward fluid flux after the Lushan earthquake in the intermediate-field, while coseismic static volumetric strain may account for the hydrological changes after the Kangding earthquake in the near-field. This is the first time that temperature-time series are used to quantify continuous earthquake-related changes in groundwater fluxes. In situ temperature monitoring can provide insights into earthquake-driven hydrologic responses, and also offer additional information to identify temporal changes in crustal strain or hydraulic properties.

【 授权许可】

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