6.9 Magnitude Tremor and Tsunami Snafu Disrupt Business as Usual
6.9 magnitude earthquake that rattled homes and offices at 8:24 a.m
Photo: Eyspsy Radio / Anetone Sagaga
Business as usual was disrupted on Monday by a 6.9 magnitude earthquake that rattled homes and offices at 8:24 a.m., causing authorities to issue a Tsunami Advisory for Samoa.
At 9 a.m., the Tsunami Advisory was downgraded to a Tsunami Watch and by 9:45 a.m. the watch was cancelled.
Officials with the National Emergency Operations Centre (N.E.O.C.) explained that by 9:45 a.m. the time had already lapsed for any tsunami waves to hit the country.
N.E.O.C. officials appeared in a video announcement on Monday morning to give the country the all clear and provide details on the tsunami notices that were disseminated earlier in the day.
Samoa’s first doctor of meteorology, Dr. Luteru A. Tuvale with the Samoa Meteorological Service (S.M.S.) said the earthquake struck at 8:24 a.m.
After analysing the initial information received, the Met Service issued a Tsunami Advisory seven minutes later at 8:31 a.m. which alerted the country to a potential tsunami.
Upon further analysis of the earthquake information, the Met Service determined the quake was stronger than first thought.
The tremor registered a magnitude of 6.9 o the Richter Scale, said Dr. Tuvale.
Based on the true strength or “value” of the quake, the Met Service then elevated the tsunami notice to a Tsunami Watch which means Samoa should prepare for a tsunami, he said.
The multiple tsunami messages did cause some chaos and confusion on Monday morning with residents posting on social media about a “Tsunami Warning” urging family and friends to head to higher ground.
But the information on tsunami messaging issued by the Met Service conflicts with information from the International Tsunami Information Center (I.T.I.C.) and the Pacific Tsunami Warning Center (P.T.W.C.) which says that a Tsunami Watch indicates the lowest level alert.
According to the I.T.I.C., a Tsunami Watch occurs first “to alert emergency management officials and the public of an event which may later impact the watch area.” At this stage people should listen for more information and stay poised to act or move.
After further analysis of the information available, the Tsunami Watch can be elevated or upgraded to a Tsunami Advisory which “is issued when a tsunami with the potential to generate strong currents or waves dangerous to those in or very near the water is imminent, expected, or occurring,” according to the I.T.I.C. When there is a Tsunami Advisory, the public must stay away from beaches and coastlines.
The Tsunami Warning is the highest alert level.
It is issued when a tsunami with the potential to generate widespread inundation is imminent, expected, or occurring. That is when people in inundation zones must move inland or get to higher ground.
This is according to information from the the I.T.I.C. and the P.T.W.C.
When a felt earthquake occurs the Met Service does issue a different type of statement to simply say there is no tsunami threat for the country.
If the Government of Samoa uses or follows the same alert levels for tsunami bulletins, the switch from “Tsunami Advisory” to “Advisory Watch” was not “elevated” as explained by N.E.O.C. officials.
The bulletin was downgraded.
Based on the order the information was received, bulletins should have begun with a “Tsunami Watch” and then elevated to a “Tsunami Advisory.”
Dr. Tuvale said when determining the value of an earthquake, the Met Service must analyse information from numerous machines hence the initial 6.4 bulletin and Tsunami Advisory issued at 8:31 a.m.
When the final value of the quake was determined to be a magnitude 6.9, the Met Service issued the Tsunami Watch, he added.
“That is why we issued an advisory then after the value was confirmed, a watch was issued,” said Dr. Tuvale.
He noted that the Met Service works with numerous partner agencies including the Pacific National Tsunami Warning Center to make sure information disseminated to the public is uniform.
After the scientific work was done, the time for any waves to hit the country had lapsed and the watch was cancelled, said Dr. Tuvale.
He said the Met Service is always monitoring earthquakes “every minute” of the day, ready to issue bulletins to the public.
Agafili Shem Leo, Chief Executive Officer (C.E.O.) of the Ministry of Cabinet and Prime Minister (M.P.M.C.), who oversees N.E.O.C., explained that there are different levels for tsunami bulletins which assists their work and the work of emergency first responders like firefighters and police.
Members of the public, in Samoa and American Samoa, were posting questions about sirens across social media platforms.
However, Agafili said that the strength of the tremors did not warrant the use of warning sirens.
It is the Tsunami Warning that triggers the use of the sirens, he explained.
“But once we hit a tsunami warning then you leave your dwellings and move to evacuation sites already assigned,” said Agafili.
Training and evacuation drills are ongoing, he said.
He noted that employees in the private sector and in government left their offices and went home.
Agafili assured the public that it was safe for everyone to return to work and for fishermen to return to the ocean to resume fishing.
“On social media, there is a lot of misinformation going around. N.E.O.C. is here when there are emergencies. Don’t be worried while we do our work. There is nothing to worry about,” he said.
He expressed his thanks for the heavy rains of Monday morning and urged the public to catch rainwater “because we don’t know what the weather will bring,” Agafili said.
Lealaisalanoa Frances Brown-Reupena, C.E.O. for the Ministry of Natural Resources and Environment (M.N.R.E.) pointed out that there is “a big difference” between the destructive earthquake of 2009.
“In 2009 that was an 8.1 magnitude. Today it was a 6.9, there is a big difference. We are safe,” she said.
The Monday 6.9 magnitude quake was the fourth tremor felt in Samoa in the span of two days.
The Met Service issued a second felt earthquake bulletin on Monday afternoon.
It was the second earthquake of the day and registered at a magnitude 5.1 on the Richter Scale.
It did not pose a tsunami threat for Samoa.
So far there have been five felt earthquakes for the month of December.
Experts at the Met Service said early this year there are about 200 earthquakes per month for Samoa.
Only a small percentage of the tremors are felt.