Magma movement detected under São Jorge, Azores

(ORDO NEWS) — The seismic volcanic crisis in the Manadas volcanic fissure system on the island of São Jorge, Azores, Portugal, has been ongoing since March 19, 2022.

A noticeable change was recorded on April 6, when volcanic-tectonic earthquakes were detected, indicating the movement of magma at depth. Volcanic alert remains at 4 out of 6. The last eruption of this volcano was in 1808 (VEI 1).

On April 6, the Azores Center for Volcano Seismic Information and Observation (CIVISA) reported that for the first time since the beginning of the crisis, they recorded volcanic-tectonic earthquakes.

Volcano-tectonic earthquakes, also known as hybrid earthquakes, occur when high-frequency tectonic shocks merge with low-frequency volcanic ones, said Fatima Viveros of the CIVISA1 regional center.

They are evidence of magma moving at depth, Viveros said, adding that more such earthquakes are expected.

On April 4, two days before the discovery of hybrid earthquakes, CIVISA warned that “there is a real possibility of a volcanic eruption” in São Jorge, but “there is no evidence that it is imminent.”2

Since the crisis began, CIVISA has recorded over 26,000 earthquakes, with the strongest M3.8 at 21:56 UTC on March 29th.

The last eruption of this volcano occurred in 1808 – volcanic explosiveness index 1.

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