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Homeland Security monitoring underwater volcano shaking Manu’a

USGS graphic of underwater volcano near Ta'u American Samoa
Eruption unlikely but NOAA team will come with specialized instruments

Pago Pago, AMERICAN SAMOA — A team of specialists from the National Oceanic and Atmospheric Administration (NOAA) are heading to American Samoa with instruments to analyze the strength of the underwater volcano activities affecting Manu’a.

This followed a statement issued Tuesday evening by the Emergency Operations Center (EOC) of reports of the ground shaking due to what they described as Vailulu’u underwater volcano activities.

“We are trying to get the first NOAA official on Thursday’s flight and the rest of the team will arrive next week,” said American Samoa Homeland Security Director (ASDHS), Samana Semo Ve’ave’a in response to Samoa News questions.

He said the Thursday flight is full and the official is on standby and the ASG has requested that Hawaiian Airline provide a seat, given the special circumstances.

“At the moment, we have activated both the Emergency Operations Center in Ta’u and Ofu and they are sending in reports on an hourly basis with the latest one at 11 a.m today (Wednesday).

“And it’s just minor shakes around Ta’u and Ofu, and the EOC staff in Manu’a are confident that it doesn’t warrant any concern, but we are taking every precautionary measure to ensure that we are ready for when anything happens.

“I’m not saying anything will happen or the volcano will erupt, but we have to prepare for the worst as it is better to be prepared than to be caught by surprise,” said Samana.

According to the ASDHS Director, the team that arrives next week will bring instruments including seismometers and seismographs that measure volcanic earthquakes, and tell if magma is rising through the crust.

On Wednesday evening a statement was issued over reports of grounds shaking due to what they described as Vailulu’u underwater volcano activities.

“Located between Tau and Rose Atoll, Vailulu’u is an unpredictable and very active underwater volcano presenting a potential long-term volcanic hazard,” said the statement.

The latest statement issued by ASDHS outlines the synopsis of the  earthquakes felt in the Manu'a Islands over the past few days, from the U.S. Geological Survey (USGS) team regarding the Felt Earthquakes in American Samoa.

“Earthquakes have been felt in the Manuʻa islands of American Samoa over the past few days and are ongoing.

“These earthquakes may be caused by a volcano, but a large explosive eruption is extremely unlikely.

“Experts are assessing the situation.”

According to the USGS the earthquakes have been felt by residents of Taʻū (the largest of the Manuʻa group of islands) in American Samoa, for a few days and are ongoing and that a team of experts is working on understanding the cause of these earthquakes, and will share more information when it is available.

“There is a chance these earthquakes are caused by a volcano, but an eruption like Hunga Tonga– Hunga Ha'apai in Tonga earlier this year is extremely unlikely.

“If you are at the coast in American Samoa and feel a strong or long duration earthquake, see a sudden rise or fall of the ocean, or hear a loud roar from the ocean, a tsunami may follow and you should immediately move to higher ground.

“The U.S. Geological Survey’s Volcano Hazards Program is responsible for monitoring volcanoes in American Samoa.

“Current seismic monitoring capabilities are limited to a station in Apia and the U.S. Geological Survey is working on a plan to extend seismic monitoring to the island of Taʻū.

“Residents can be of great assistance to these monitoring efforts by noting and reporting accurate times that they feel earthquake shaking to the National Weather Service Office in Pago Pago.”

Furthermore the USGS says that currently, the Samoa hotspot is thought to be beneath the Vailuluʻu seamount, which is located about 45 kilometers (28 miles) east of Taʻū island.

“Vailuluʻu’s summit, which has a 2 kilometer (1.2 mi) wide and 400 meter (0.25 mi) deep caldera, rises 4,200 meters (13,779 feet) from the sea floor to a depth of 593 meters (1,946 feet) below sea level.

“It most recently erupted in 2003, during which a 300-meter-high (980 feet) submarine cone named Nafanua formed.

“Prior to that, earthquake swarms in 1995 and 1973 are thought to have been associated with other Vailuluʻu eruptions.

“An additional earthquake swarm occurred in 2000.

“Evidence exists for both explosive and effusive eruptions of Vailuluʻu: in 1973, underwater acoustic signals of explosions were recorded and Nafanua cone that formed in 2003 is primarily composed of pillow lavas.”

To the people of Manu’a, the ASDHS Director urged them not to panic and adhere to emergency evacuation sites in any case there is a turn of events.

“Our EOC teams consist of first responders, Police Officers, EMS, firefighters and homeland security staff are on standby,” said Samana. 

Adding that even the Manu’a people are “confident” that it’s unlikely the volcano will erupt.

Link to the USGS information regarding the volcano