| − | [[Image:Focal_depth.gif|thumb|300px|Diagram of dipping slab with different focal depth events]]The '''focal depth''' refers to the depth of an [[earthquake]] hypocenter.<ref>USGS</ref> | + | [[Image:Focal_depth.gif|thumb|300px|Diagram of dipping slab with different focal depth events]]The '''focal depth''' refers to the depth of an [[earthquake]] hypocenter.<ref>http://earthquake.usgs.gov/learning/glossary.php?term=focal%20depth</ref> |