Method and device for determining moment magnitude of microseism event

Abstract

The invention discloses a method and device for determining the moment magnitude of a microseism event, and the method comprises the steps: carrying out the Fourier transform of longitudinal and transverse waves collected by a detector, and determining the main frequency of the microseism event; determining a propagation path and propagation duration of the microseism event according to the time difference data of the longitudinal and transverse waves acquired by the detector; according to the maximum amplitude value of the longitudinal and transverse waves collected by the detector, the mainfrequency of the microseism event and the propagation duration of the microseism event, determining the maximum amplitude value of the longitudinal and transverse waves at the rock fracture position of the microseism event; determining the seismic moment of the microseism event according to the maximum amplitude value of the longitudinal and transverse waves at the rock fracture position of the microseism event, the propagation path of the microseism event, the rock density and the propagation speed of the longitudinal and transverse waves collected by the detector; and determining the momentmagnitude of the microseism event according to the seismic moment of the microseism event. The calculation precision of the moment magnitude of the microseism event can be improved.

Description

technical field [0001] The invention relates to the technical field of microseismic events, in particular to a method and device for determining the moment magnitude of microseismic events. Background technique [0002] The Richter scale is a magnitude scale proposed by American seismologists Charles Francis Richter and Beno Gutenberg in 1935. It is based on the amplitude and period of seismic waves observed at a certain distance from the epicenter to calculate the source of the earthquake. However, due to the saturation overflow phenomenon of the Richter scale, it is difficult to measure earthquakes greater than magnitude 8 or microearthquakes less than magnitude 0. [0003] Stratum fractures can be assumed to be the result of a pair of moments of equal magnitude and opposite directions. The seismic moment reflects the energy of earthquake dislocation from a mechanical point of view, and the moment magnitude can better describe the energy released by natural earthquakes. U...

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Problems solved by technology

However, microseismic events that induce rock fractures such as hydraulic fracturing occur at a depth of several thousand meters below the surface, and the fracture surface and dislocation amount are small, so that the existing seismometer measurement method can obtain the moment magnitude of microseismic events. less accurate

[0004] For the above problems, no effective solution has been proposed

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