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地震 ›› 2024, Vol. 44 ›› Issue (4): 209-224.doi: 10.12196/j.issn.1000-3274.2024.04.014

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福建地区地震温泉地球化学观测网点勘选方法及指标探索

廖丽霞, 周跃勇, 邓聪, 黄艳丹   

  1. 福建省地震局, 福建 福州 350003
  • 收稿日期:2024-04-15 修回日期:2024-09-20 出版日期:2024-10-31 发布日期:2024-12-16
  • 作者简介:廖丽霞(1965-), 女, 福建龙岩人, 高级工程师, 主要从事地震地下流体监测预测研究。
  • 基金资助:
    中国地震局地震科技星火计划攻关项目(XH21013); 中国地震局监测预报司震情跟踪项目(2024010305)

Research on the Selection Method of Seismic Hot Spring Observation Network Points and Exploration of Geochemical Selection Indicators in Fujian Region

LIAO Li-xia, ZHOU Yue-yong, DENG Cong, HUANG Yan-dan   

  1. Fujian Earthquake Agency, Fuzhou 350003, China
  • Received:2024-04-15 Revised:2024-09-20 Online:2024-10-31 Published:2024-12-16

摘要: 温泉与构造和地震密切相关, 温泉地球化学可用于构造研究和地震预测, 但关于如何选择温泉连续观测点的研究则较少报道。 本文通过对2020年9月—2023年9月福建全区温泉与中国台湾地震的相关性分析, 总结了温泉观测网点选择及映震灵敏组分判定的方法。 据此构建了流体地球化学观测网并应用于预测实践, 还在2022年9月18日中国台湾ML6.8地震中得到验证。 方法的核心是应用温泉逸出气的氦、 氖、 碳同位素, 探寻具有深部循环、 携带丰富深部信息的温泉观测点。 这些温泉点的突出特点是温泉气中幔源同位素示踪流体的贡献大, 具体表现为幔源氦占比和δ13CCO2均超区域均值、 δ13CCO2测值明显偏离其与CO2体积百分比的拟合线, 且这些温泉点大多位于断裂带交会处, 断裂多深切到莫霍面。 研究团队在这些温泉点采集水样进行水化学主量离子连续观测, 并在具丰富逸出气的南埕自冒泉开展气体流速连续观测。 通过阈值分析法将观测结果与中国台湾区域6级以上地震进行相关性分析, 统计各观测点及各测项的映震能力, 并应用R值评估法进行预报效能评估。 评估结果排名靠前且映震效能高者可最终选定为潜在的有效流体地球化学地震监测点。 研究结果可为地震行业勘选温泉地球化学监测站场址和有效的地震前兆观测项目提供参考指标、 实操方法及实例借鉴。

关键词: 温泉地球化学, 幔源氦占比, δ13CCO2, 短临预测, 映震灵敏组分, 勘选指标

Abstract: Hot springs are closely related to tectonics and earthquakes. There is a consensus that hot spring geochemistry can be used for tectonic research and earthquake prediction. However, there is little disclosure on how to select continuous observation points for hot springs. Based on the correlation analysis between the hot springs in Fujian and the earthquakes in Taiwan, China from September 2020 to September 2023, this paper summarizes the methods for selecting hot spring observation sites and determining the sensitive components of seismic reflection. Based on this, a fluid geochemical observation network was constructed and applied to prediction practice, successfully predicting the ML6.8 earthquake in Taiwan, China on September 18, 2022. The core of the method is to use helium, neon, and carbon isotopes from hot springs to explore hot springs with deep circulation and rich deep information. The outstanding characteristics of these hot springs are the large contribution of mantle source fluid in hot spring gas, reflected in the high ratio of mantle source helium and the mean value of the δ13CCO2 double high region, the significant deviation of δ13CCO2 measured value from the fitting line with CO2 volume percentage, the intersection of structural fault zones, and the fact that most faults reach deep into the Moho plane. Water samples were collected from these hot springs for continuous observation of water chemical major ions, and the gas flow rate of Nancheng spontaneous spring with abundant escaping gas was continuously observed. The correlation analysis between the observation results and the earthquakes above M6 in the Taiwan, China was carried out by using the threshold analysis method. The seismic mapping capability of each observation point and each measurement item was calculated, and the R-value evaluation method was applied to evaluate prediction efficiency. Those with high evaluation results and high seismic mapping efficiency could be finally selected as potential effective fluid geochemical seismic monitoring points. The results can be used as a reference for selecting sites for hot spring geochemical monitoring stations and effective earthquake precursor observation projects in the earthquake industry.

Key words: Geochemistry of hot springs, The proportion of mantle derived helium, δ13CCO2, Short term and imminent prediction, Reflective seismic sensitive components, Selection indicators

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