Focus (Hypocenter)
Focus (Hypocenter): In the seismology branch of geology, a focus, or hypocenter, refers to the specific place where an earthquake rupture originates. The focus, or hypocenter, underlies the epicenter when an earthquake occurs at a dip-slip fault, strike-slip fault, oblique-slip fault, or listric fault.
In the event of an earthquake, geologists, and seismologists of the United States Geological Survey (USGS) use numerous global positioning data devices, and seismographs, to locate the epicenter, as well as the focus, or hypocenter.