2021年青海玛多MS7.4地震前后CO异常变化研究

CO anomalies before and after the 2021 Maduo MS7.4 earthquake in Qinghai Province

摘要:

地震前后气体地球化学信息的研究在地震监测预报中具有较高的应用价值。为研究2021年5月22日青海玛多M_S7.4地震与CO时空变化之间的关系,在以瓦里关大气观测站地面数据验证大气红外探测仪(AIRS)反演数据可靠性的基础上,提取玛多M_S7.4地震前后AIRS反演的CO数据,通过滑动均值法、差值法对玛多地震前后不同尺度的CO浓度数据进行处理和分析。结果表明:利用卫星遥感数据提取CO地球化学信息是可靠的。时间上,玛多M_S7.4地震前两个月CO浓度开始波动,出现峰值,地震发生后恢复平静;空间上,震中位置的CO浓度在近地面变化尤其明显,震中及附近区域的CO浓度从3月开始逐渐升高,由离散分布逐渐向震中和发震断裂带聚拢靠近,到4月底达到最大异常18.60×10^-9,异常高值中心的连线与发震断层江错断裂走向、地表破裂分布一致。排除背景值和季节变化的影响,推断CO浓度异常变化是地震引起的,主要归因于地下气体释放和岩石挤压碰撞产气,气体逸散后在大气圈中发生的一系列化学反应起次要作用。

Abstract:

The investigation of gas geochemical information before and after an earthquake has high application value in earthquake monitoring and prediction. Thus, this paper investigates the relationship between the spatio-temporal variation of CO and the M_S7.4 earthquake that occurred in Maduo County, Qinghai Province, on May 22, 2021. The accuracy of CO data obtained from the Atmospheric Infrared Sounder (AIRS) was compared with ground data from the Waliguan atmospheric observation station. The CO data retrieved by AIRS before and after the M_S7.4 earthquake were extracted, from which the CO concentrations before and after the earthquake were processed and analyzed using the sliding mean method and difference method. Results indicate the reliability of extracting CO geochemical information from satellite remote sensing data. The CO concentration began to fluctuate and peak two months before the earthquake and then recovered after the earthquake. Furthermore, the change in CO concentration in the epicenter and its vicinity was particularly obvious near the surface. This gradually increased from March, gathered near the epicenter and the seismogenic fault, and eventually reached the maximum value of 18.60×10^-9 by the end of April. The line connected to the centers of the abnormally high values is consistent with the strike of the seismogenic fault and the surface rupture distribution. Barring the influence of background value and seasonal change, it is inferred that the abnormal change in CO concentration is caused by the M_S7.4 earthquake. The CO anomaly can be mainly attributed to the underground gas release and gas production caused by rock extrusion and collision, while the gas chemical reactions in the atmosphere play a secondary role.