Probable source of November tremor

Many of you will remember the harmonic tremor that happened back in November of last year, and all of the speculation about its source. Some of you will also remember that several seismologists tentatively traced its origins back to a several-months-long seismic swarm near Mayotte, an island north of Madagascar, and said they thought the tremor likely signified a huge underwater eruption.

Well, a high-resolution bathymetric survey by the French Navy just found this:

Roughly translated: BEFORE-AFTER: new #volcano from #Mayotte: data acquired by the Beautemps-Beaupré (French Naval ship) in 2014 (left) and 01/07/2019 (right): 800m high for 5km wide with a high point at 2568m on an average background around 3300m below sea level

EDIT: categorized under #special-events