Dom João de Castro Bank

Dom João de Castro Bank is a large submarine volcano located in the central north Atlantic Ocean, between the islands of São Miguel and Terceira in the archipelago of the Azores.HistoryThe first historical reference correlated with the perilous submarine volcanoes between São Miguel and Terceira occurred from the sinking of two ships of the French corsair Henry Tourin, in the spring of 1718.The last major eruption associated with this region occurred on 31 December 1720. Beginning as a submarine eruption, it eventually built to a Surtseyan eruption that resulted in the formation of a circular island 1.5km long, 250m altitude island.Designated the Ilha Nova, it remained above sea-level for only two years, reaching a height of 180m and diameter of 900m. Marine erosion and ocean swells reduced and degraded the cone's size considerably, so that by 21 July 1722 the Conselho da Marinha Português was advised that island had disappeared. (Oliveira, 1943).After two centuries of disputed references to the existence of the island, on 28 July 1941 the hydrographic ship NH D. João de Castro identified its position and cataloged the morphology of the bank. In keeping with nautical tradition at its discovery, the bank inherited its name.The most recent seismic events from the region occurred from 4 June 2012, when incrementally increasing tremors affected the region. A maximum seismic event was recorded from the islands of São Miguel and Terceira, equivalent to levels III/IV on the Mercalli Scale.GeographyIt remains a seismically active zone, lying midway between the islands of São Miguel and Terceira, rising to within 13m of the sea surface. The volcano has a large fumarole field, its top approximately 1600m in total.