探究2023年2月6日土耳其7.8级双震的成因  

Investigating Generation of the February 6,2023 M7.8 Double Earthquakes in Tirkiye

作　　者：郭贵娟 孙凤霞[2,3] 杜建国 GUO Gui-juan;SUN Feng-xia;DU Jian-guo(l.Seismological Press,Beijing 10o081,China;Institute of Earthquake Forecasting,China Earthquake Administration,Beijing 100036,China;School of Earth Sciences and Resources,China University of Geoscience(Beijing),Beijing 100083,China)

机构地区：[1]地震出版社,北京100081 [2]中国地震局地震预测研究所,北京100036 [3]中国地质大学(北京)地球科学与资源学院,北京100083

出　　处：《地震》2024年第3期1-20,共20页Earthquake

基　　金：高压物理与地震科技联合实验室开放基金项目(2022HPPES01);国家自然科学基金项目(41373059)。

摘　　要：为了促进地震预测和揭示地震成因奥秘,依据地壳结构、地震地质、地球物理、地热流体地球化学资料和地震序列发生的时空特征,综合研究了2023年2月6日土耳其南部7.8级双震的成因。2023年2月6-17日土耳其南部发生7.8级双震,伴随了几十次M≥5.0强余震和数千次M<5.0的余震。地震震源深度分布范围为5~22 km,在大约500 km×300 km的范围内震中分布形成一条NE向、宽约40 km、长约300 km和另一条近EW向、宽约50 km、长约240 km的震中分布密集带。研究区下存在地壳内的低速高导层,大地热流密度高值异常,布格重力负异常、航磁异常以及深大断裂带,表明该区岩石圈内存在地幔流体聚集、形成超高压流体的条件。地幔流体局部聚集形成超高压流体的过程可视为孕震过程。2023年2月6-17日不同时段的地震震源空间分布的阶段性集中和深度变化表明,地幔高能密流体的持续供给或者供给量增大形成了孕震体。当孕震体内流体压力大于围岩束缚强度(围岩抗压强度+静水压力)时发生流体隐爆,产生地震。流体通过运移-聚集-爆炸-运移-聚集-爆炸……的循环方式运移,同时产生7.8级双震及其余震。这从能量来源和产生地震波的角度较合理地解释了在有限的范围内非连续、非弹性地体中连续产生7.8级双震和M≥4.0余震的现象。Generation of the double M,7.8 earthquakes of 6 February 2023 in southern Turkiye was comprehensively studied based on the crust structure and seismogeologic,ge-ophysical and geothermal fluid geochemistry data as well as the spatial-temporal character-istics of the seismic sequence occurrences,in order to improve earthquake prediction and earthquake generation research.The double M7.8 earthquakes took place on 6 February 2023 in southern Turkiye,companying dozens of M≥5.O earthquakes and several thou-sands of M<5.0 aftershocks in the duration of 617 February.Depths of the earthquakes focus range from 5 km to 22 km.The earthquake epicenters predominantly distributed in two belts in an area of about 500 km ×300 km.One belt of NE trending has a length of 300 km and width of 40 km,another belt of EW trending has a length of 240 km and width of 50 km.Existences of low velocity and resistivity zone in the crust,high heat flow a-nomaly,negative Bouguer gravity anomaly,aeromagnetic anomaly and the deep-cut fault zones in the study area indicate that there are the necessary requirements for mantle-de-rived fluid accumulation and formation of super-pressure fluid bodies in the lithosphere of the area.The process of locally mantle-derived fluid accumulation to build super-pressure fluid bodies can be considered as the process of seismogenesis.The periodical accumulation of earthquake hypocenters in space and variations of the hypocenter depths during 617 February indicated that increasing supplement of high-energy-density fluids derived from the mantle to the earthquake source bodies,resulted in repeated increases of fluid pres-sure.Cryptoexplosion occurred when the fluid pressure in the source bodies exceeded the strength of the surrounding rocks(compressive strength+hydrostatic pressure),produ-cing earthquakes.The high-energy-density fluids migrated in the way of the inflate-explo-sion-deflate-inflate-explosion-deflate cycle,which produced the M7.8 double earthquakes and aftershocks.Therefore,the M7.8 double earthquake

关 键 词：7.8级双震 隐爆作用 地幔流体 地热流体孕震 地震成因 土耳其 

分 类 号：P594.1[天文地球—地球化学]