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Report on Sao Jorge (Portugal) — 30 March-5 April 2022


Sao Jorge

Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
30 March-5 April 2022
Managing Editor: Sally Kuhn Sennert

Please cite this report as:

Global Volcanism Program, 2022. Report on Sao Jorge (Portugal). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 30 March-5 April 2022. Smithsonian Institution and US Geological Survey.

Weekly Report (30 March-5 April 2022)

Sao Jorge

Portugal

38.65°N, 28.08°W; summit elev. 1053 m

All times are local (unless otherwise noted)


A seismic swarm beneath the W half of São Jorge began at 1605 on 19 March, with earthquakes along the Manadas volcanic fissure system between Velas (S side of the island) and Fajã do Ouvidor (N coast). On 31 March there were 714 seismic events detected, according to a preliminary analysis of seismic records. As the week progressed, the number of daily events fluctuated from 397 on 1 April to 592 on 5 April; magnitudes were relatively low. The Alert Level remained at V4 (on a scale of V0-V6).

Geological Summary. The dominantly basaltic São Jorge Island is 55 km long and 6.5 km wide. It was formed by fissure eruptions beginning in the eastern part of the island. The western two-thirds of the island contains youthful, fissure-fed lava flows resembling those on neighboring Pico Island. Lava effused from three locations above the south-central coast during 1580, producing flows that reached the ocean. In 1808 a series of explosions took place from vents along the south-central crest of the island; one of the vents produced a lava flow that reached the southern coast. Submarine eruptions have also been reported on several occasions from a submarine ridge to the SE. The 1964 event offshore W of Velas was considered "probable" by Madiera and Brum da Silveira (2003), who also provided 14C dates for several other Holocene eruptions.

Source: Centro de Informação e Vigilância Sismovulcânica dos Açores (CIVISA)