An overview of Ly Son Islands, off the coast of Quang Ngai Province, the islands was formed by five volcanoes millions of years ago. However, geological experts say the volcanoes could become active in the future. Photo courtesy of Bui Thanh Trung

Experts from the Vietnam Institute of Geosciences and Mineral Resources (VIGMR) said recent field surveys showed that craters on the islands were round and sharp, suggesting the volcanoes were very young.

The last volcanic eruption here was recorded in the central coast of Vietnam, 100km off the south central coast of Phan Thiet City in Binh Thuan Province, where it formed the Hòn Tro, or Ile des Cendres (Island of Ashes, or a group of submarine volcanoes) in 1923.

Dr. Nguyen Xuan Nam from VIGMR said rock samples collected from Thoi Loi Mountain show they dated 20,000 years ago, while basalt samples at the other volcanoes were formed less than 10,000 years ago.

“Following data and surveys from the national research project on the Neo-tectonic in previous years, coastal areas of Quang Ngai Province are situated in high risk centre of active fault, including of earthquakes and volcanic eruptions ranging from Thua Thien-Hue to Binh Thuan,” Nam said.

“Ly Son Islands terrain structure could shake due to active volcanoes putting big construction buildings in danger.”

He said at least nine points of thermal water were found in the province, evidencing of a deep breakable ground structure.

Aquatic farms have been developed in the sea off Ly Son Islands of Quang Ngai Province. Photo courtesy of Tran Lan Anh

“Construction of a small building only needs ground stability tests, but high-rise buildings must be developed using a deep terrain structure assessment for quake resistance structure plans,” he said.

Volcano forecasts are not yet available in Vietnam, but Ly Son Islands and coastal zones in Quang Ngai are marked as the volcanic centre, he added.

Nam said five underwater craters were found in the water off the islands, and two others were seen at Mu Cu Islet. So, possible active volcanoes could impact any construction projects on the islands.

He also said a group of researchers and scientists had found a population of paleontological coral reefs over an area of 20,000 square metres extending 400 metres along the coast, northeast of the islands.

It’s a unique complex of fossilised coral – believed to date from 4,000 to 6,000 years ago – on the islands’ coast, he added.

Tran Tan Van, an expert in geology, said nobody could be sure if volcanoes would become active on Ly Son Islands or not, but craters on the islands were identified as young and active volcanoes. 

Active volcanoes

World volcanologists believe that if the last eruption of a volcano took place less than 10,000 years ago, it should be considered an active volcano, which can erupt anytime in the future.

Tran Tan Van said active volcanoes in Vietnam might be related to the Manila trench subduction zone (an active convergent plate margin between the East Sea and the northern Philippines).

This means that volcanoes could occur in the coastal central region of Vietnam in linkage with the active tectonics along the Manila trench.

He said the Ministry of Natural Resources and Environment compiled a map on tsunami and earthquakes in the coastal central Vietnam a few years ago, and only earthquake measurements and a tremor monitoring system were established, but an early quake warning system was not yet built.

The islands of ancient volcanoes are a favourite tourist destination in the province. Photo courtesy of Le Xuan Tho

Van, who is former director of VIGMR, said a series of construction projects on the islands should include seismic and tsunami factors in the plan.

At a scientific seminar in the province few years ago, Dr. Setsuya Nakada, chair of the Advisory Committee of the Global Geo-Parks Network, said at least five volcanoes and potentially active volcanoes occurred in central and south of Vietnam in the Neogene-Quatenary period.

He said volcanic activities in Vietnam were related to the subduction zone (Ring of Fire in Pacific region), and the formation of the East Sea.

Most of the 22,000 population on the islands make their living from garlic farming. Photo courtesy of Le Xuan Tho

Ly Son Island, known as the ‘Kingdom of Garlic’ in Vietnam, is a tranquil destination with 22,000 inhabitants, most of whom make their living from garlic, spring onions and fishing.

Conservationists and scientists have warned that booming construction, mass tourism and proposals for an airport could damage the terrain structure, and that new buildings must be resistant to quakes and tsunamis.

Tourism has boomed since the islands connected to the national grid in 2014, hosting 260,000 tourists each year and creating VND317 billion (US$14 million) in revenue.

According to the latest report from the island, 14 hotels, including one four-star hotel, 57 guest houses and 62 homestays are open, offering more than 1,000 rooms for up to 3,000 tourists.

The 10.4 square kilometre islands have invested VND800 billion in developing 17 infrastructure projects in the last 10 years.

Source: Vietnam News

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Geographical indication given to Ly Son garlic

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