Açores_Swarm News

 

A swarm of earthquakes has started yesterday under the northwestern half of São Jorge Island (Azores), with 19 quakes of magnitudes between 2.0-3.5 and many more smaller ones.

Some of the tremors were felt be the population. There is no clear information yet as to the cause of this seismic swarm, in particular whether it is likely caused by a magmatic intrusion at some depth, which could be a precursor or an indication of the re-awakening of the volcano, which last erupted more than 200 years ago in 1808.
To better interpret these quakes, more geophysical data is needed, especially whether there is ground deformation as well, something to expect if magma influx at depth is indeed the cause of the quakes.

The last volcanic activity from São Jorge volcano occurred more than 200 years ago in 1808. The volcanic activity on the narrow, elongated island is mainly related to fissure eruptions from the central rift system.