Ruby Seamount
Ruby Seamount is an active volcanic seamount in the Northern Mariana Islands region of the Pacific Ocean about 50 km (31 mi) north-west of Saipan.[5][1] It is in a region where the Pacific Plate is subducting under the Philippine Sea Plate producing arc volcanism. EruptionsA submarine eruption occurred during a period of about 12 hours between 14 and 15 September 2023, and it also erupted in 1966 and between 11 and 23 October 1995.[5][1] GeologyRuby Seamount is a stratovolcano with a more shallow southern peak,[5] and is part of the nine volcano Southern Seamount Province of the Mariana Arc, in the Izu–Bonin–Mariana Arc.[3]: 151 Its location is consistent with it being a back-arc extension associated volcano. Samples of lava have been characterised as arc tholeiitic basalts,[3] suggestive that the magma source was from mantle overlying, not beneath, the subducting Pacific Plate.[4]: 15092–3 The age of the volcano is unknown but nearby basalts have been dated at about 2 million years old,[4]: 15094–6 so it likely started forming more recently than this. Hydrothermal activity was demonstrated in 2006 with alkaline, ferrous ion and carbon dioxide venting at 200 m (660 ft) depth.[2]: 7, 11 The ratio of CO2 / 3He flux observed at Ruby is amongst the highest ever reported, which is consistent with volcanism involving a deep magma source from slab derived carbonate containing rocks.[2]: 18 Depth revisionPrior to the 1995 eruption the depth was accepted as 230 m (750 ft),[1] but several reports of shallower depths followed the eruption including one of only about 60 m (200 ft) exist.[5] A high quality survey in 2003 gave a depth of 180 m (590 ft) with the peak of North Ruby having a depth of 726 m (2,382 ft).[6]: 16 The next high quality survey in 2006 gave a new depth of 175 m (574 ft).[2]: 11 EcologyA unique ecosystem of crabs and limpets has been described on the flanks of the volcano.[7] NameIt was first named as Ruby Volcano in the 1973 paper that described some of the 1966 eruption evidence.[8] References
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