Teaching local residents about the risks faces challenges. On a cloudy day in September, Heidi Jiggle negotiates a dig in the slippery road in Seldovia, Alaska. A hill covered with a small church rises above her town – below, the bay, fishing boats gently sway; on the shore, Linwood Bar & Grill, the Crab Pot grocery store, and dozens of houses on stilts.
Tsunamis in Alaska
Alaska is prone to two types of tsunamis. Tectonic tsunamis, linked to the long chain of volcanic islands that form the southern part of the state; those islands form the northern edge of the Ring of Fire, a geologically active area that generates about 90 percent of the world’s earthquakes. Tracking those islands, underwater, is the Aleutian Subduction Zone, a trench where massive plates of solid rock interlock and accumulate friction slowly. Once or twice a year, the subduction zone generates earthquakes strong enough to warn of a tsunami; about every 300 to 600 years, it erupts in a giant earthquake that sends devastating tectonic tsunamis to Alaska’s shores.
Submarine Landslide Tsunamis
The sprawling 34,000-mile wilderness coastline in the state presents a second, lesser-known threat: submarine landslide tsunamis. The southern coast of Alaska is surrounded by active volcanoes and hundreds of fjords filled with unstable cliffs, under which lies a thick layer of mud and sediment in the deep waters. Relatively small earthquakes, common in Alaska, shake the unstable landscape, causing landslides above and below sea level that displace massive amounts of water. Resulting tsunamis can reach coastal communities within minutes. With the accelerating melting of glaciers and subsequent erosion in those areas due to climate changes, landslide-generated tsunamis are becoming more likely.
Challenges and Tsunami Preparedness
The mix of risks means that “in Alaska, we have the ability to have one really bad day,” says Barrett Salisbury, a state earthquake geologist and tsunami scientist. Seldovia is located about 137 miles southwest of Anchorage on the rugged Kenai Peninsula, right above the convergence point of tectonic plates. It is one of 159 communities along the Alaska coast, including tourist hubs hosting cruise ships carrying 4,000 passengers, small Russian Orthodox villages, and the 228 officially recognized indigenous tribal settlements in Alaska. Small and isolated, it serves as a case study of the complex layers that make Alaskan communities particularly vulnerable.
Planning for tsunamis is difficult. The science of tsunamis is in its early stages, only emerging when computer modeling became possible in the 1980s. Scientists in Alaska lack the necessary technology to predict tsunamis before they strike the state, as they happen so quickly. For many Alaskans, the last major tsunami to hit the state in 1964 is a distant memory. False alarms cause evacuations at least once a year, leading people to wonder why they should leave with no waves showing up. These challenges are complicated by a culture that may be wary of outside experts. “I know the history,” says Elena Solemani, the government team’s tsunami modeler working at the Alaska Earthquake Center at the University of Alaska in Fairbanks.
As community leaders and scientists prepare for the next big wave, they face a perpetual question: how can they convince people that they are at risk of an unpredictable disaster that can skip several generations and is guaranteed to be catastrophic when it occurs? A deadly strike.
In
On March 27, 1964, the second largest earthquake in recorded history struck off the southern coast of Alaska, measuring 9.2. Streets in Anchorage cracked in half, and an entire neighborhood fell into the sea. Within minutes, underwater slopes along parts of the coast failed, causing localized tsunamis. Then the tectonic tsunami struck, submerging communities repeatedly for hours. More than 20 tsunamis hit Alaska, resulting in the deaths of 106 people across the state and causing $284 million in damages. In Seldovia, the ground shook for nearly three minutes and then sank permanently by 3.5 feet. The highest wave from the tectonic tsunami that reached the town, at 26 feet tall, was of little consequence, arriving at low tide. But during the next extreme high tide, the town was underwater and had to be demolished and rebuilt.
Darlene Crawford, chief of the Seldovia Tribe, recalls holding on to cupboards while her house shook around her, seemingly endlessly, and then leading four of her young children to high ground on that cold night. The effects of Good Friday’s earthquake continue to this day; she said the urban renewal project that removed the town divided the community, and only one crab processing plant returned, altering the crab fishing-based economy. “It changed life in Seldovia significantly,” she said. “The town was empty for a long time.”
However, Seldovia was better off than most towns, partly because the town faces the sheltered Kachemak Bay. On the opposite side of the Kenai Peninsula, communities like Seward, where Crawford’s parents lived, were not so fortunate. There, waterfront warehouses and fuel storage tanks slid into Resurrection Bay, only to be swept back to the shore within minutes by towering waves over 30 feet. The native village of Chenega in Alaska, on an island near Seward, lost a third of its population and was never resettled. Its residents were initially scattered across Alaska before a new community was built on a nearby island.
Next time, Seldovia may not be so lucky. Tsunamis do not provide warning as much as they are inevitable. And if the next giant earthquake strikes at high tide, the waves could wipe Seldovia off the map.
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