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When an earthquake occurs in the information that is given about the characteristics of the earthquake, two terms are almost always associated, epicenter and hypocenter. Actually the difference is very simple, the hypocenter is the portion of the fault which is affected by the slip that produces the earthquake e the epicenter e the corresponding point on the surface by drawing a hypothetical vertical line from the hypocenter. The area around the epicenter it is generally the area where the earthquake is felt with greater energy and does more damage but it is not always said, see the terrible earthquake that hits Mexico City in 1985. The magnitude was of 8.1 and the epicenter was identified near the coast but the worst damage occurred well 380km from the epicenter, in Mexico City due to the geology of the subsoil of the city he favored seismic amplification phenomena. The whole city was devastated and more than 10,000 victims were reported.
It is then defined focal depth the distance between the epicenter and the hypocenter. A distance that as we know can vary from a few kilometers to hundreds of kilometers and depends on it the energy with which the earthquake is felt on the surface.The deepest earthquake that has ever been registered happened in Okhotsk sea on May 24, 2013, had a magnitude of 8.3 on the Richter scale e a depth of 609km.