Ruby Seamount is an active volcanic

seamount A seamount is a large submarine landform that rises from the ocean floor without reaching the water surface (sea level), and thus is not an island, islet, or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abruptly a ...

in the

Northern Mariana Islands The Northern Mariana Islands, officially the Commonwealth of the Northern Mariana Islands (CNMI), is an Territories of the United States, unincorporated territory and Commonwealth (U.S. insular area), commonwealth of the United States consistin ...

region of the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

about north-west of

Saipan Saipan () is the largest island and capital of the Northern Mariana Islands, an unincorporated Territories of the United States, territory of the United States in the western Pacific Ocean. According to 2020 estimates by the United States Cens ...

. It is in a region where the Pacific Plate is subducting under the

Philippine Sea Plate The Philippine Sea plate or the Philippine plate is a tectonic plate comprising oceanic lithosphere that lies beneath the Philippine Sea, to the east of the Philippines. Most segments of the Philippines, including northern Luzon, are part of ...

producing

arc volcanism A volcanic arc (also known as a magmatic arc) is a belt of volcanoes formed above a subducting oceanic tectonic plate, with the belt arranged in an arc shape as seen from above. Volcanic arcs typically parallel an oceanic trench, with the arc lo ...

Eruptions

A 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.

Geology

Ruby Seamount is a

stratovolcano A stratovolcano, also known as a composite volcano, is a typically conical volcano built up by many alternating layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with ...

with a more shallow southern peak, and is part of the nine volcano Southern Seamount Province of the Mariana Arc, in the Izu–Bonin–Mariana Arc. Its location is consistent with it being a back-arc extension associated volcano. Samples of lava have been characterised as arc

tholeiitic The tholeiitic magma series () is one of two main magma series in subalkaline igneous rocks, the other being the calc-alkaline series. A magma series is a chemically distinct range of magma compositions that describes the evolution of a mafic ...

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

s, suggestive that the magma source was from mantle overlying, not beneath, the subducting Pacific Plate. The age of the volcano is unknown but nearby basalts have been dated at about 2 million years old, so it likely started forming more recently than this. Hydrothermal activity was demonstrated in 2006 with alkaline, ferrous ion and

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

venting at depth. 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.

Depth revision

Prior to the 1995 eruption the depth was accepted as , but several reports of shallower depths followed the eruption including one of only about exist. A high quality survey in 2003 gave a depth of with the peak of North Ruby having a depth of . The next high quality survey in 2006 gave a new depth of .

Ecology

A unique ecosystem of

crab Crabs are decapod crustaceans of the infraorder Brachyura (meaning "short tailed" in Greek language, Greek), which typically have a very short projecting tail-like abdomen#Arthropoda, abdomen, usually hidden entirely under the Thorax (arthropo ...

s and

limpet Limpets are a group of aquatic snails with a conical gastropod shell, shell shape (patelliform) and a strong, muscular foot. This general category of conical shell is known as "patelliform" (dish-shaped). Existing within the class Gastropoda, ...

s has been described on the flanks of the volcano.

Name

It was first named as Ruby Volcano in the 1973 paper that described some of the 1966 eruption evidence.

References

External links

Youtube:The United States Has a New Volcanic Eruption; Ruby Seamount
{{Northern Mariana Islands, , collapse_state=collapsed Izu–Bonin–Mariana Arc Volcanoes of the Northern Mariana Islands Stratovolcanoes of the United States