Gravitational and elastic energies stored in crustal volumes activate normal versus strike-slip and thrust seismogenic faults  

作　　者：Carlo Doglioni 

机构地区：[1]Dipartimento Scienze della Terra,Sapienza University,Rome,Italy [2]Istituto Nazionale di Geofisica e Vulcanologia,Rome,Italy

出　　处：《Geoscience Frontiers》2024年第6期194-206,共13页地学前缘（英文版）

摘　　要：Shallow crustal faults are passive features mobilized by the dissipation of the potential energy and the shear stress accumulated in the brittle volume surrounding them.However,the stored energy in the volume differs from the tectonic setting,i.e.,it is mainly gravitational in extensional tectonic settings,whereas it is elastic in strike-slip and contractional tectonic environments.In extensional settings,below about 1 km,the horizontal tensile stress is overwhelmed by the confining pressure of the lithostatic load,and it becomes positive,i.e.compressive.Therefore,there is no horizontal tension in extensional tectonic settings and the pro-gravity motion of the crustal volume is provided by the lithostatic load,which is the vertical maximum principal stress.The elastic energy is rather accumulated by the maximum horizontal principal stresses,i.e.,iso-gravity in transcurrent settings and counter-gravity in contractional tectonic settings.The different relation with the gravitational force in the different tectonic settings generates several relevant differences in the three main tectonic environments.The extensional tectonic settings,both in continental and oceanic rift zones generate normal fault-related earthquakes,i.e.,pro-gravity movements,or graviquakes.They differ from the other tectonic setting because are marked by(i)lower energy and lower differential stress to activate faults with respect to strike-slip and contractional tectonics;(ii)lower maximum earthquake magnitude;(iii)a larger number of low magnitude earthquakes in extensional settings because the crust moves downward as soon as it can move,whereas contractional settings require larger accumulation of energy to move counter-gravity;(iv)consequently,the b-value of the Gutenberg-Richter is higher than 1 and the aftershocks are more numerous and last longer in extensional settings;(v)the downward motion of the hangingwall determines more diffuse cataclastic deformation with respect to the other tectonic settings because the lithostatic load works every

关 键 词：Pro-gravity tectonics Iso-gravity tectonics Counter-gravity tectonics Graviquake Elastoquake 

分 类 号：P315[天文地球—地震学]