Abstract:Until recently, it is believed that the rupture speed above the pressure wave is impossible since spontaneously propagating ruptures are driven by the energy released due to the rupture motion, which is transferred through the medium to the rupture tip region at the maximum speed equal to the pressure wave speed. However, the apparent violation of classic theories has been revealed by new experimental results demonstrating supersonic shear ruptures. This paper presents a detailed analysis of the recently disco… Show more
Frictional stick–slip instability along pre‐existing faults has been accepted as the main mechanism of earthquakes for about 60 years, since it is believed that fracture of intact rocks cannot reflect such features inherent in earthquakes as low shear stresses activating instability, low stress drop, repetitive dynamic instability, and connection with pre‐existing faults. This paper demonstrates that all these features can be induced by a recently discovered shear rupture mechanism (fan‐hinged), which creates dynamic ruptures in intact rocks under stress conditions corresponding to seismogenic depths. The key element of this mechanism is the fan‐shaped structure of the head of extreme ruptures, which is formed as a result of an intense tensile cracking process, with the creation of inter‐crack slabs that act as hinges between the shearing rupture faces. The preference of the fan mechanism over the stick–slip mechanism is clear due to the extraordinary properties of the fan structure, which include the ability to generate new faults in intact dry rocks even at shear stresses that are an order of magnitude lower than the frictional strength; to provide shear resistance close to zero and abnormally large energy release; to cause a low stress drop; to use a new physics of energy supply to the rupture tip, providing supersonic rupture velocity; and to provide a previously unknown interrelation between earthquakes and volcanoes. All these properties make the fan mechanism the most dangerous rupture mechanism at the seismogenic depths of the earth's crust, generating the vast majority of earthquakes. The detailed analysis of the fan mechanism is presented in the companion paper “New physics of supersonic ruptures” published in DUSE. Further study of this subject is a major challenge for deep underground science, earthquake and fracture mechanics, volcanoes, physics, and tribology.
Frictional stick–slip instability along pre‐existing faults has been accepted as the main mechanism of earthquakes for about 60 years, since it is believed that fracture of intact rocks cannot reflect such features inherent in earthquakes as low shear stresses activating instability, low stress drop, repetitive dynamic instability, and connection with pre‐existing faults. This paper demonstrates that all these features can be induced by a recently discovered shear rupture mechanism (fan‐hinged), which creates dynamic ruptures in intact rocks under stress conditions corresponding to seismogenic depths. The key element of this mechanism is the fan‐shaped structure of the head of extreme ruptures, which is formed as a result of an intense tensile cracking process, with the creation of inter‐crack slabs that act as hinges between the shearing rupture faces. The preference of the fan mechanism over the stick–slip mechanism is clear due to the extraordinary properties of the fan structure, which include the ability to generate new faults in intact dry rocks even at shear stresses that are an order of magnitude lower than the frictional strength; to provide shear resistance close to zero and abnormally large energy release; to cause a low stress drop; to use a new physics of energy supply to the rupture tip, providing supersonic rupture velocity; and to provide a previously unknown interrelation between earthquakes and volcanoes. All these properties make the fan mechanism the most dangerous rupture mechanism at the seismogenic depths of the earth's crust, generating the vast majority of earthquakes. The detailed analysis of the fan mechanism is presented in the companion paper “New physics of supersonic ruptures” published in DUSE. Further study of this subject is a major challenge for deep underground science, earthquake and fracture mechanics, volcanoes, physics, and tribology.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.