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In seismology, the depth of focus or focal depth is the depth at which an earthquake occurs. Earthquakes occurring at a depth of less than 70 km (43 mi) are classified as shallow-focus earthquakes, while those with a focal depth between 70 km (43 mi) and 300 km (190 mi) are commonly termed mid-focus or intermediate-depth earthquakes. [1]
The path of deep-focus earthquake seismic waves from focus to recording station goes through the heterogeneous upper mantle and highly variable crust only once. [3] Therefore, the body waves undergo less attenuation and reverberation than seismic waves from shallow earthquakes, resulting in sharp body wave peaks.
In its most general sense, the word earthquake is used to describe any seismic event that generates seismic waves. Earthquakes can occur naturally or be induced by human activities, such as mining, fracking, and nuclear tests. The initial point of rupture is called the hypocenter or focus, while the ground level directly above it is the epicenter.
Hypocenter (Focus) and epicenter of an earthquake. An earthquake's hypocenter or focus is the position where the strain energy stored in the rock is first released, marking the point where the fault begins to rupture. [3] This occurs directly beneath the epicenter, at a distance known as the hypocentral depth or focal depth. [3]
Seismology (/ s aɪ z ˈ m ɒ l ə dʒ i, s aɪ s-/; from Ancient Greek σεισμός (seismós) meaning "earthquake" and -λογία (-logía) meaning "study of") is the scientific study of earthquakes (or generally, quakes) and the generation and propagation of elastic waves through planetary bodies.
The temblor, which measured 4.8 on the Richter scale, was considered a shallow earthquake by the U.S. Geological Survey, meaning that it occurred at a depth of zero to 70 kilometers below ground.
These are deep earthquakes, megathrust earthquakes, and outer rise earthquakes. Deep earthquakes happen within the crust, megathrust earthquakes on the subduction interface near the trench, and outer rise earthquakes on the subducting lower plate as it bends near the trench. Anomalously deep events are a characteristic of subduction zones ...
Shallow earthquakes cause more damage than intermediate- and deep-focus ones since the energy generated by the shallow events is released closer to the surface and therefore produces stronger shaking than is produced by quakes that are deeper within the Earth. [1] [12] The peak ground acceleration generated was 993 gal (1.01 g). [13]