When the 7.1 magnitude Iniskin earthquake hit at about 1:30 a.m. Jan. 24, it didn’t wake one Homer-grown seismologist — but that’s because Kasey Aderhold, a 2006 Homer High School graduate, now lives in Washington, D.C. Aderhold had an app set up on her smart phone to alert her in the event of a 6.5 or stronger quake. She’d turned her phone off, though.
“I woke up to a whole bunch of snow and then all these text messages. I immediately went online and looked at stuff, the aftershock experiences, the questions people were asking on Facebook,” Aderhold said. “It was really fun, actually.”
While Aderhold and other scientists assess the Iniskin earthquake, emergency management officials and utility companies are looking at what they did right and what can be fixed. Kenai Peninsula Borough Emergency Management Director Scott Walden said he was pleased at the fast response.
“Considering the impact it had as far as jolting everybody out of bed, it was fairly concerning to me initially,” Walden said. “Within a few minutes after it stopped, I was able to touch base across the peninsula.”
Aderhold, 27, graduated last May with a doctorate in earth sciences from Boston University. She now works with the Incorporated Research Institutions for Seismology, or IRIS, a group that helps coordinate earthquake research. Aderhold helps manage seismic instrumentation with the Transportable Array, a network of seismometers being installed across Alaska. In the summer of 2015, 30 stations were put in with the array, with another 70 to be installed this summer and 70 more in 2017.
One station, P19K, was put in last summer less than 10 miles from the earthquake’s epicenter in Iniskin Bay north of Augustine Volcano and about 75 miles west of Homer.
“What’s nice is there were a whole bunch of stations where the earthquake occurred,” Aderhold said. “There’s going to be some really good results from the earthquake.”
Alaska lucked out with the Iniskin quake because of its depth, about 80 miles. That puts the quake within the slab of the Pacific plate as it dives beneath the North American plate, Aderhold said. The 1964 Great Alaska Earthquake, was shallower and on the interface between those plates.
“That’s where you get things like the 1964 quake that can cause tsunamis,” Aderhold said of shallow quakes.
Intermediate depth earthquakes aren’t as well understood as shallow quakes. Seismologists tend to study the shallower quakes because they cause more damage.
“It’s just now that people are starting to look into them,” Aderhold said of the intermediate zone quakes. “Every earthquake can teach us something. This one will be well studied. There will be lots of papers coming out.”
The effect of the Iniskin quake also had a lot to do with the geology of southcentral Alaska. Aderhold said a good measurement of severity is the 1-10 scale of intensity. That’s calculated by seismometers, but also by anecdotal reports from more than 1,800 people who filled out a “Did You Feel It?” online survey on a U.S. Geological Survey website. Some people reported very strong shaking ranked at VII. A shaking intensity map showed moderate to strong shaking on the lower Kenai Peninsula and very strong shaking on the upper peninsula and in downtown Anchorage. Walden said emergency managers in Seward reported less shaking.
“It really depends on the ground type,” Aderhold said. “I’m not sure what’s going on in Homer that makes it better.”
The worst damage from the Iniskin quake happened in Kenai, when four homes burned on Lilac Lane after a gas explosion. The quake also put a 150-foot crack in Kalifornsky Beach Road. Enstar Natural Gas is still investigating the Lilac Lane event and how the quake caused it, said Lindsay Hobson, a spokesperson for Enstar.
Walden said his office quickly assessed the quake’s damage.
“We were really amazed that within a short period of time we were able to narrow down the resources needed to the problems on Kalifornsky Beach Road and the city of Kenai’s response,” he said.
One defect Walden noted was the lack of an American Red Cross office here.
“If there was one thing that could change overnight, it would be having the presence of the Red Cross back on the Kenai Peninsula,” Walden said.
Hobson said after the quake Enstar did a leak survey. That survey is almost complete. It found one leak in Anchorage, and crews isolated the leak without a disruption of service. Homer had no reports of damage or impact.
Hobson said Homer’s new natural gas system includes a feature required by federal regulations since 2010: an excess flow valve, or EFV, in service lines. That valve turns off gas to buildings if there is any damage upstream of the service line on the distribution line.
Walden said that after the quake many people questioned how individuals responded.
“That was the biggest question. ‘What should I have done differently?’” he said.
Some people responded by sitting tight. Others stood in doorways. Some left homes. The best advice is to “drop, cover and hold on” — sit down, get under a desk or table to protect from falling objects, and hang on to desk legs. American buildings, particularly those in earthquake zones, are built to withstand heavy shaking. Walden said most injuries come from falling objects.
“That’s the idea behind drop and cover,” Walden said. “Generally things like light fixtures, ceiling tiles will be the things that come down right away.”
In the event of a gas leak, though, getting outside a building is the right thing to do, Hobson said. She said after a quake people should listen for gas hissing and smell for mercaptan, the skunk-like odor added to natural gas. If leaking gas is detected, “the safest course of action is to get out of the house and evacuate.” People also should call 844-763-5542 to report leaks.
If leaking gas isn’t detected, don’t turn off the gas supply to the house, Hobson said. Enstar technicians have to reconnect gas if turned off. In a big disaster, it could take a while for technicians to do that.
“If it’s a cold January week, that could be a difficult situation,” Hobson said.
Walden said there’s one lesson to be learned from the quake: review disaster plans. The borough Office of Emergency Management has links to resources (see box, left). A good training exercise is the annual Great Alaska Shakeout, held Oct. 20. Participants can sign up.
“I’m really hoping to see a spike in interest this year,” he said.
• Kenai Peninsula Borough Office of Emergency Management: kpb.us/emergency-mgmt
• Great Alaska Shakeout: shakeout.org/alaska
• Division of Homeland Security and Emergency Management: ready.alaska.gov/Preparedness/Outreach