Before the necessary period of earthquake observation, the center was allowed to be the position where the
topmost damage passed,( 2) but the subterranean fault rupture may be long and spread face damage across the
entire rupture zone. As an illustration, in the magnitude7.9 Denali earthquake of 2002 in Alaska, the center
was at the western end of the rupture, but the topmost damage was about 330 km( 210 mi) down at the
eastern end.( 3) Focal depths of earthquakes being in international crust substantially range from 2 to 20
kilometers(1.2 to12.4 mi).( 4) Continental earthquakes below 20 km( 12 mi) are rare whereas in subduction
zone earthquakes can appear at depths deeper than 600 km
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