It’s a coin toss whether a large, destructive earthquake will hit the Hawaiian Islands in the next decade.
It’s a coin toss whether a large, destructive earthquake will hit the Hawaiian Islands in the next decade.
Given this island’s track record for such upheavals of earth and accompanying tsunamis, residents should be prepared for damaged infrastructure and communications blackouts, and families should have an emergency plan in place, said Wes Thelen, a seismologist with the U.S. Geological Survey Hawaiian Volcano Observatory.
The crushing mass of the island’s two volcanoes and their settling movements outward cause many of the quakes, generally at the transition zone with the sea floor, Thelen said. Because the shifts happen so close to shore, anything over a magnitude 7.0 can produce an instant tsunami.
“If you are at the beach and you feel strong shaking, the next thing you need to do is get to higher ground,” Thelen said. “You will have only minutes.”
The Ka‘u quake of 1868, spawned by the south flank of Kilauea volcano sliding seaward, was a record magnitude 7.9, throwing up a 60-foot tsunami and causing 46 deaths. Writing for “Scribner’s Weekly” in 1871, missionary and early volcanologist Titus Coan described the scene: “The streams ran mud, the earth was rent in thousands of places, and the very streets of Hilo cracked open. Horses and their riders were thrown to the ground and multitudes of people were prostrated by the shocks … (and) made seasick by their frequency.”
The 1951 magnitude 6.9 quake at Kealakekua Bay cracked roads, caused landslides, knocked out telephone poles and collapsed 200 water tanks. In 1975, a magnitude 7.7 quake triggered a 48-foot wall of water at Kalapana that killed two campers and injured 19 others.
HVO scientists will present information on these earthquakes and others, and engage the public in dialogue at a series of talk stories around the island starting later this month.
The magnitudes 6.7 and 6.0 2006 Kiholo Bay quakes are still fresh in people’s minds, Thelen said. There were also very strong, damaging quakes in the 1950s, and it will be interesting to hear residents share their experiences of those events as well, Thelen said.
“We will try to make sure there is something there for everyone,” Thelen said. “I don’t think anyone will come out of there bored.”
The discussions are a prelude to the Great Hawaii ShakeOut at 10:16 a.m. Oct. 16, when thousands of Hawaii residents will join more than 20 million worldwide in earthquake preparedness exercises. Some 13,000 people have registered as being part of the drills statewide, including 1,600 people from public schools in Hilo and Waimea.
Thelen said there are misconceptions about how to respond in an earthquake. Standing in a doorway or running outside are two outdated notions. It is safer to be under a table or desk, he said.
“The newest thinking is drop, cover and hold on,” he said. “Anything over a 6.5 and you’ll be having trouble standing anyway. Get under a table or other protection and hold onto it because that table can dance away.”
Improved building codes and construction have essentially negated the danger that most buildings will actually fall down, Thelen said, and it’s risky to run out of a building while the ground is moving and objects are falling.
“The danger is things coming off of walls,” he said. “That’s where most people get injured in quakes, not from the structure collapsing around them.”
Emergency experts also recommend texting rather than phoning immediately after a disaster to avoid overwhelming provider capacity. Flooding the bandwidth with calls right after a disaster hinders 911 emergency calls and responders being able to talk to each other.
The first earthquake talk story will be held at 6:30 p.m. Wednesday at the Ocean View Community Center, followed by a presentation Sept. 23 at the Kilauea Visitor Center in Hawaii Volcanoes National Park. Kailua-Kona’s event will be held at 6:30 p.m. Oct. 15 at the Makaeo Events Pavilion at the Old Kona Airport Park. That date is the anniversary of the quakes at Kiholo Bay.
HVO is also trying to obtain a venue in Waimea, Thelen said.
“The best way to get the message out is word of mouth,” Thelen said. “I’d like to arm people with information that is sound and useful so they can go out and tell their friends.”
For more information about the Great Hawaii ShakeOut visit shakeout.org/hawaii. HVO is online at hvo.wr.usgs.gov.
Email Bret Yager at byager@westhawaiitoday.com.