MADRID—A series of small earthquakes in Spain’s Canary Islands has put authorities on alert for a possible volcanic eruption, with one official saying Thursday there is “intense seismic activity” in the area off northwest Africa.
Authorities have detected more than 4,200 temblors in what scientists are calling an “earthquake swarm” around La Palma island since last Saturday. An earthquake swarm is a cluster of quakes in one area during a short period and can indicate an approaching eruption.
