English word coseismal comes from English co-, English seismal (Seismic.)

Detailed word origin of coseismal

Dictionary entry	Language	Definition
co-	English (eng)	(mathematics) of the opposite, of the counterpart; dual. Partner or subordinate in an activity. To the same degree. Together; mutually; jointly.
seismal	English (eng)	Seismic.
coseismal	English (eng)	Of or pertaining to a line on a map connecting places simultaneously affected by a seismic event.

Words with the same origin as coseismal