The existence of underwater volcanoes in Pacitan Regency, East Java adds to the list of underwater volcanoes that Indonesia has. But this newly discovered underwater volcano doesn't yet have an official name.
As a country surrounded by the Pacific Ring of Fire, Indonesia does not only have volcanoes on land, but also has underwater volcanoes. The distribution of volcanoes on land is more commonly known, because undersea volcanoes cannot be observed directly considering their location is thousands of meters below sea level.
The following are underwater volcanoes in Indonesia that are known so far:
1. Pacitan Undersea Volcano
Found under the sea in the southern part of Pacitan Regency, the mountain is almost as tall as Mount Bromo in East Java. This anonymous mountain was discovered by the Geospatial Information Agency (BIG) and a number of agencies in a series of surveys on the Indonesian Continental Shelf (LKI) conducted September-November 2022 in the southern regions of Java, Bali and Nusa Tenggara.
Quoted from the BBC, BIG has just identified its shape, so it cannot be confirmed whether this mountain is active or not. The mountain which is currently suggested to be named 'Giri Salam' has a height of 2,200 meters. The peak is at a depth of 3,800 meters above sea level.
So far, BIG has identified 11 underwater mountains. It is possible that there are still other seamounts, because the mapping of the Indonesian seabed has not reached 10%.
2. West Kawio Undersea Volcano
One of the active underwater volcanoes in Indonesia is in Kawio Village, Marore Islands District, Sangihe Islands Regency, North Sulawesi Province. It is located west of Kawio, so researchers call it the West Kawio Undersea Volcano.
This discovery, as quoted from Mongabay, was made through an expedition, the implementation of deep-sea research cooperation, between Indonesia and the United States, represented by the Marine and Fisheries Research and Development Agency of the Ministry of Maritime Affairs and Fisheries and the United States National Oceanic and Atmospheric Administration [NOAA]. This program is called the Indonesia-US Expedition Sangihe-Talaud which was conducted from 24 June to 6 August 2010.
The height of this mountain reaches 3,400 meters, almost equivalent to Mount Semeru which is the highest mountain on the island of Java, which is 3,676 meters above sea level.
3. Hobal Undersea Volcano
Reporting from the Instagram account of the Center for Volcanology and Geological Disaster Mitigation (PVMBG), the underwater volcano Hobal or Ile Werung is near Lembata Island, Atadei District, Lembata Regency, East Nusa Tenggara.
The height of the Hobal underwater volcano is not known, but Hobal's last activity occurred in 1999, when white smoke came out of the sea at a height of about 100 meters.
4. Banua Wuhu Underwater Volcano
The Banua Wuhu underwater volcano is near the Sangihe Islands, North Sulawesi. The height of the Banua Wuhu underwater volcano is 400 meters from the seabed.
The last activity of Banua Wuhu occurred in 1919, namely on February 2, 1919 releasing lava. Then on April 2, 1919 Banua Wuhu again released lava and explosive eruptions which caused high tides and caused explosions which damaged coconut trees and burned 25 houses on the east coast. The next day, April 3, 1919, there was an eruption with a plume of steam as high as 4-5,000 meters which was accompanied by a violent eruption.
5. Submarine Volcano 1922
Submarine Volcano 1922 underwater volcano is located around the Sangihe Talaud Archipelago, North Sulawesi. The height of this mountain is unknown, but its location is estimated to be at a depth of 5,000 meters below sea level.
As the name suggests, the last activity of the 1922 Submarine Volcano occurred in 1922 after a series of earthquakes that had occurred since 1912. It was recorded that there had been several submarine earthquakes with epicenters between Mindanao Island and Sangihe Talaud Islands.
6. Nieuwerkerk Undersea Volcano
The Nieuwerkerk underwater volcano is a twin volcano located near Central Maluku Regency, Maluku Province. The height of the underwater volcano Nieuwerkerk I is more than 1,900 meters from the seabed at a depth of 2,285 meters above sea level.
Meanwhile, the height of the Nieuwerkerk II underwater volcano is more than 1,800 meters from the seabed at a depth of 2,325 meters above sea level. Between the two underwater volcanoes is about 7 kilometers.
Nieuwerkerk I and II peaks are separated by a saddle with a depth of 600 meters from Peak II. Nieuwerkerk's last activity occurred in 1927.
7. The Jersey Undersea Volcano
The Yersey underwater volcano is near the South Banda Sea. The height of the mountain which is at a depth of 4,200 meters above sea level is not yet known. However, it is thought that there is a ridge rising some 600 meters from the seafloor identified as Yersey.
Yersey's recent activity is unknown, but the Snellius expedition in 1929 found a reef-like array at a depth of more than 3,800 meters caused by an underwater eruption.
The Banda basin with a depth of more than 4,200 meters has an underwater ridge with two active volcanoes namely Wetar volcano and Batutara volcano.
8. Emperor of China Volcano
The Emperor of China underwater volcano is in the western part of the South Banda Sea with a shape resembling a shield volcano. The height of this mountain is 1,500 meters from the seabed and is at a depth of 2,850 meters above sea level. The last activity of the Emperor of China volcano occurred in 1927.