The seismic crisis unfolding in the Azores: earthquakes accompanying a rarely observed submarine eruption?

A swarm of earthquakes on the seabed west of a volcanic island in the Azores (Faial) presents an exciting opportunity to find out potentially how submarine volcanic cones form and this in turn helps us to understand the risks from submarine eruptions. The swam lies at one end of an elongated volcano (Condor Seamount) where there are small volcanic cones and ridges. We will install 4 seismometers on the seabed around the site to record further earthquakes over two months. By accurately locating those earthquakes, we will be able to determine the geometries of faults and cracks filled with lava (dykes). If there has been an eruption, the seabed will have changed shape - this will be worked out from multibeam echo-sounder data collected in a new sonar survey in the summer of 2020. The combined results will show us whether there has been an eruption and if so how that eruption related to the molten lava supplied deeper in the Earth. In addition, we will be able to reassess seismic waves that have travelled through the adjacent submarine volcano to see if those waves have unusually low velocities expected for a magma chamber. The new results from the seismometers will be used to update software used by government scientists in the Azores to work out where earthquakes occur and their magnitudes, hence their monitoring service for the local population. This will further help us work out the nature of the earthquake swarm (whether associated with subterranean movement of lava or movements on faults). Submarine volcanic eruptions are less frequent in the Atlantic compared with the Pacific Ocean, but are a risk to ships, seabed cables and to local populations where associated earthquakes and landslides cause tsunamis. Understanding this Azorean event will help characterize this broader threat, of importance to the UK given its large sea areas, including those around volcanically active Ascension and Tristan da Cunha islands.

Submarine volcanic eruptions can affect infrastructure laid on the seabed, such as telecommunications and power cables, and shipping (buoyancy loss), hence the results will be relevant to the cables and transportation industries, insurance and government (navy, planning). The UK in particular has a broad interest in understanding risks posed by submarine eruptions, given that it has the 5th largest EEZ globally and its Atlantic islands of Ascension and Tristan da Cunha are in volcanically active areas. Ascension Island is critical for rapid military resupply of the Falkland Islands, given political risks associated with requests to use all other airfields at comparable latitudes. A shallow submarine eruption near the island could disrupt RAF access to Wideawake Airfield and tsunamis from submarine landslides could present a risk to the capital Georgetown. Government and company employees will be reached first via key intermediaries, such as the British Geological Survey (government geohazard assessments for UK Overseas Territories including the Atlantic islands) and an FCO panel tasked with hazards and with Manchester involvement.
The broader public and industry interest in this area will also be reached via University of Manchester publicity avenues, such as our department's blog, the NERC OBS facility blog and via the NOAA news outlets (we will contribute to the NOAA/ASPIRE programme publicity surrounding their realtime "telepresence" ROV dives: https://oceanexplorer.noaa.gov/okeanos/).
Within the Azores, the local agency (CIVISA) website is used as the main communication between government scientists and the population, so it can be used to reassure the public of the relatively modest threats from this likely deep submarine eruption. Risks need to be relayed sensitively so as not to cause undue alarm - we will compose blogs for that site jointly with our CIVISA collaborators.
A wider effort coordinated by the InterRidge (www.interridge.org) emphasizes the economic benefits and threats to remote populations on islands and from their adjacent seamounts. We already have led a workshop on this subject at the Portuguese hydrographic institute in Lisbon and will update our news through the InterRidge website with the project results (www.interridge.org), also via researchgate, Twitter, Linkedin and other social media.