判识水氡地震前兆的方法——以甘肃清水温泉水氡异常为例

地震前兆异常性质的准确判断是提高地震预测水平的前提。 据国内外相关统计, 真正具有地震预测意义的地震前兆异常数量十分有限。 因此, 厘清震前异常与地震的关系对今后异常识别意义重大。 2017年8月8日九寨沟M_S7.0地震前4个月, 甘肃清水温泉水氡出现大幅波动异常变化。 为了判断这次异常与九寨沟地震的关系, 在异常持续期间, 通过抽水实验、 水化学组分以及氢氧同位素组成分析, 并结合九寨沟地震发震构造以及其他前兆异常空间分布特征, 对水氡异常成因机理进行了深入分析。 结果表明: 对于水氡与水位的变化关系, 实验与实际观测结果一致, 都呈正相关变化; 实验中水氡变化幅度与实际观测的相当; 水化学组分以及氢氧同位素测试结果显示清水温泉水氡异常期间, 来自地壳深部的流体并未增加; 清水温泉区其他前兆没有出现明显的短期异常变化; 在空间上清水温泉与九寨沟地震震源区被两条深大断裂隔开。 因此, 清水温泉水氡大幅异常变化并非九寨沟地震的短期前兆异常, 而是企业抽水开始时间、 持续时间以及用水量不固定引起的。 该实例为地震前流体前兆异常性质的准确判定提供了更为可靠的方法和思路。

The Method for Identify the Earthquake Precursor of Water RadonTaking the Water Radon Anomaly of Qingshui Hot Spring in Gansu Province As an Example

Correct judgements for anomaly features is the precondition for enhancing our ability to do the earthquake prediction. According to relative statistic, the true anomalies of earthquake are quite limited. It is important to study the relationship between the precursors and following earthquakes. The radon of Qingshui hot spring fluctuated drastically the 4th month before Jiuzhaigou M_S7.0 earthquake on August 8, 2017. In order to identify the relationship between the radon anomaly and the earthquake, the cause and mechanism of this radon anomaly were studied deeply by pumping tests, analyzing isotopes and hydrochemistry components of Qingshui hot spring.The seismogenic structure of Jiuzhaigou earthquake and some other anomalies were also analyzed. The results showed that the test results are consistent with the actual observation. The water radon variation is positively correlated with water level variation but with water temperature.The proportion of fluid from deep crust did not increase according to composition of hydrogen and oxygen isotope and hydrochemistry. There seems to be little probability of seismogenic process of Jiuzhaigou earthquake caused rupture of Qingshui hot spring area.The radon anomalous of Qingshui hot spring is not the short-term anomaly for the 2017 Jiuzhaigou M_S7.0 earthquake. It was caused by manual pumping. This study provides a more reliable method for identifying the anomalies of fluid before earthquakes.