Seismic Signals of the Wushi <i>M<sub>S</sub></i>7.1 Earthquake of 23 January 2024, Viewed Through the Angle of Hydrogeochemical Characteristics
On 23 January 2024, a <i>M</i><sub>S</sub>7.1 earthquake struck Wushi County, Xinjiang Uygur Autonomous Region, marking the largest seismic event in the Southern Tianshan (STS) region in the past century. This study investigates the relationship between hydrothermal fluid cir...
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| Main Authors: | , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-04-01
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| Series: | Applied Sciences |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2076-3417/15/9/4791 |
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| Summary: | On 23 January 2024, a <i>M</i><sub>S</sub>7.1 earthquake struck Wushi County, Xinjiang Uygur Autonomous Region, marking the largest seismic event in the Southern Tianshan (STS) region in the past century. This study investigates the relationship between hydrothermal fluid circulation and seismic activity by analyzing the chemical composition and origin of fluids in natural hot springs along the Maidan Fracture (MDF). Results reveal two distinct hydrochemical water types (Ca-HCO<sub>3</sub> and Ca-Mg-Cl). The δD and δ<sup>18</sup>O values indicating spring water are influenced by atmospheric precipitation input and altitude. Circulation depths (621–3492 m) and thermal reservoir temperatures (18–90 °C) were estimated. Notably, the high <sup>3</sup>He/<sup>4</sup>He ratios (3.71 Ra) and mantle-derived <sup>3</sup>He content reached 46.48%, confirming that complex gas–water–rock interactions occur at fracture intersections. Continuous monitoring at site S13 (144 km from the epicenter of the Wushi <i>M</i><sub>S</sub>7.1 earthquake) captured pre-and post-seismic hydrogeochemical fingerprints linked to the Wushi <i>MS</i>7.1 earthquake. Stress accumulation along the MDF induced permeability changes, perturbing hydrogeochemical equilibrium. At 42 days pre-Wushi <i>M</i><sub>S</sub>7.1 earthquake, δ<sup>13</sup>C DIC exceeded +2σ thresholds (−2.12‰), signaling deep fracture expansion and CO<sub>2</sub> release. By 38 days pre-Wushi <i>M</i><sub>S</sub>7.1 earthquake, Na<sup>+</sup>, SO<sub>4</sub><sup>2−</sup>, and δ<sup>18</sup>O surpassed 2σ levels, reflecting hydraulic connection between deep-seated and shallow fracture networks. Ion concentrations and isotope values showed dynamic shifts during the earthquake, which revealed episodic stress transfer along fault asperities. Post-Wushi <i>M</i><sub>S</sub>7.1 earthquake, fracture closure reduced deep fluid input, causing δ<sup>13</sup>C DIC to drop to −4.89‰, with ion concentrations returning to baseline within 34 days. Trace elements such as Be and Sr exhibited anomalies 12 days before the Wushi <i>M</i><sub>S</sub>7.1 earthquake, while elements like Li, B, and Rb showed anomalies 24 days after the Wushi <i>M</i><sub>S</sub>7.1 earthquake. Hydrochemical monitoring of hot springs captures such critical stress-induced signals, offering vital insights for earthquake forecasting in tectonically active regions. |
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| ISSN: | 2076-3417 |