'earthquake-related' originates from the combination of 'earthquake' and 'related', where 'earthquake' refers to a sudden shaking of the ground and 'related' means connected or associated with.

'earthquake' comes from Middle English 'erthequake', from Old English 'eorþan' (earth) and 'cwacian' (to shake). 'Related' comes from Latin 'relatus', past participle of 'referre' (to bring back).

Initially, 'earthquake' meant a shaking of the earth, and 'related' meant connected. Together, they describe anything associated with earthquakes.