Process that generates seismic waves in an earthquake
The focal mechanism of an earthquake describes the deformation in the source region that generates the seismic waves. In the case of a fault-related event, it refers to the orientation of the fault plane that slipped, and the slip vector and is also known as a fault-plane solution. Focal mechanisms are derived from a solution of the moment tensor for the earthquake, which itself is estimated by an analysis of observed seismic waveforms. The focal mechanism can be derived from observing the pattern of "first motions", whether the first arriving P waves break up or down. This method was used before waveforms were recorded and analysed digitally, and this method is still used for earthquakes too small for easy moment tensor solution. Focal mechanisms are now mainly derived using semi-automatic analysis of the recorded waveforms.[1]
^Sipkin, Stuart A. (1994). "Rapid determination of global moment-tensor solutions". Geophysical Research Letters. 21 (16): 1667–1670. Bibcode:1994GeoRL..21.1667S. doi:10.1029/94GL01429.
The focalmechanism of an earthquake describes the deformation in the source region that generates the seismic waves. In the case of a fault-related event...
isoseismal regions can be used to help determine the magnitude, focal depth, and focalmechanism of an earthquake. The first known isoseismal map was produced...
Geophysics and Volcanology, the focal depth was determined at 24.7 km (15.3 mi) beneath the High Atlas. The focalmechanism of this model displayed reverse...
almost any direction depending on the type of initiating rupture (focalmechanism). The first refinement that allowed a more precise determination of...
colleagues used dislocation theory to determine part of an earthquake's focalmechanism, and to show that a dislocation – a rupture accompanied by slipping...
has formed a series of ranges, particularly in central Kutch. The focalmechanism of most earthquakes is consistent with reverse faulting on reactivated...
magnitude of 7.9 and a maximum Mercalli intensity of VIII (Severe). The focalmechanism and hypocentral depth of the earthquake show that the earthquake was...
All the major faults show evidence of neotectonics. The earthquake's focalmechanism showed almost pure normal faulting on a plane dipping southwest at...
different maps for it based on recent tectonics, seismicity and earthquake focalmechanism. The simplest plate geometry draws the boundary from the Nansen ridge...
determine which of the two possible fault planes indicated by the focalmechanism is correct. Although there were no directly related deaths, local news...
Meteorological Agency seismic intensity scale. The earthquake had a focalmechanism corresponding to reverse-faulting at a 34.8 km (21.6 mi) depth. According...
focal depth of 12–15 km (7.5–9.3 mi) beneath the rift axis. Further away from the rift axis, focal depths can be below 30 km (19 mi). Focalmechanism...
depth of the earthquake. The geologic structure of the crust. The focalmechanism of the earthquake. The rupture directivity of the earthquake. Local...
Modified Mercalli intensity of VIII (Severe). The earthquake had a focalmechanism corresponding to reverse faulting. A magnitude 5.6 aftershock struck...
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type can have focal depths as deep as 60 km (37 mi). The earthquake had a hypocentral depth of 38.2 km (23.7 mi) and a focalmechanism of normal faulting...
due to flat-slab subduction of the African Plate. The earthquake's focalmechanism is consistent with normal faulting, trending SW-NE. From the distribution...
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largest to strike Mainland Japan since the 2011 Tōhoku earthquake. The focalmechanism of the mainshock corresponded to shallow reverse faulting along a northeast-trending...
mainshock. More than 30 aftershocks were recorded after the mainshock. The focalmechanism of the mainshock indicated primarily dip-slip faulting, but the data...
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