More than half of the City of Unalaska's tsunami sirens aren't functioning, according to city officials.
The city tested its tsunami sirens, which were purchased in 1996, on Wednesday. Three out of seven worked.
Following a number of earthquakes near Makushin Volcano earlier in the week — which prompted the Alaska Volcano Observatory to increase the volcano's alert level to "advisory" — local concern about Unalaska's emergency preparedness has been elevated.
As of Tuesday morning, the AVO had located over 700 earthquakes in the vicinity of Makushin in the eight-day period since the magnitude-4.2 quake hit on June 15, according to geologist John Power.
In the 24-year period since scientists from the program started keeping track of earthquake activity at Makushin in 1996, they've located about 8,000 earthquakes there, averaging about 300-400 per year. In the week that's passed since last week's event, scientists have seen as many earthquakes as they might expect to see at Makushin in a whole year, said Powers, although the rate of earthquakes is rapidly decreasing.
He said while the activity near Makushin represents a significant departure from background earthquake activity and may be associated with volcanic unrest, most of the quakes at Makushin have been relatively small, and if in fact the volcano does erupt, the biggest impact to Unalaska would be ash fall, not the generation of a tsunami.
"Tsunamis typically are associated with very large earthquakes in the subduction zone — magnitude sevens, eights, nines. They typically don't come from volcanoes," said Power. "So typically, what is watched for for tsunamis is very large earthquakes, much, much larger than what we've seen so far at Makushin. A magnitude four and a half as we've seen here is well below what is required to generate a tsunami."
Even so, city officials said the earthquakes have prompted staff to continue the process of repairing and updating Unalaska's siren alert system.
"The recent earthquakes in the Makushin area have brought the tsunami sirens functionality to light," said Dan Winters, the city's Public Utilities Director. "Staff is working diligently to get the sirens repaired."
The city receives official notices of tsunami watches and warnings from the AVO, state universities, and the National Oceanic and Atmospheric Administration (NOAA) through a landline phone in the dispatch center at Unalaska's Department of Public Safety, according to Interim Police Chief John Lucking.
"If that phone alarms and we get the information that there's an actual warning and not a watch, or that there's an impending wave coming, then part of the process for evacuations is that the dispatcher alarms the sirens that we have," said Lucking. "The sirens go out, a Nixle message goes out, officers make alerts in areas with support from the Fire Department, and we use any other communication means that we have to get the word out."
But with only a fraction of the city's sirens working, much of the island could remain unnotified in the event of an actual tsunami. According to Lucking, the city has funds to put towards improving the outdated siren system. But he said the arrival of the COVID-19 pandemic in Alaska in March disrupted the city's plans to move forward.
"Unfortunately, like so many other things, the COVID-19 pandemic has thrown a monkey wrench into projects moving forward," said Lucking. "But there is money on the table right now, and we do recognize that some of the sirens are not functioning regularly and dependably."
Lucking said the city is prepared to repair the sirens already in place, and will then work on improving the sirens' ability to reach people who might not currently be able to hear them sound — which might include acquiring additional sirens.
According to Winters, the cost and timeline for when the faulty sirens will be repaired and/or replaced is yet to be determined, but city staff are currently working on getting a quote from a local electrician.
Despite recognizing the faulty sirens as problematic, Lucking wanted to remind Unalaskans that the sirens are only one component of the city's alert system. The city also uses Nixle alerts — which are dependent on local cell service — and KUCB Radio for notifications during emergencies.
The city tests its tsunami sirens on the 15th of each month at noon.