A couple of Sitka residents who were fishing for halibut last month noticed an unusual feature on their depth sounder as they set gear a few miles north of town. Two-hundred feet below the surface of the water, the sounder slowly painted a picture of what appeared to be a volcano: A perfectly-formed cone about 100 feet tall, with a plum of gas trailing from the top.

Experts who’ve seen the image say it is no cause for alarm. It’s most likely a “mud volcano,” and it’s also not the only one near Sitka.

Locals don’t use rods and reels much to fish for halibut in Sitka. Rather, most set a subsistence skate – a long line baited with a dozen or more hooks that is laid right along the bottom from a slowly-moving boat.

Jacyn Schmidt was doing just this in November near the entrance to Nakwasina Sound, 5 miles north of Sitka. Schmidt was on deck, paying out the line.

“And then my friend who I was out fishing with was inside watching the depths on the sonar, and he noticed just a weird shape, and called me in to look at it with him,” said Schmidt.  

KCAW – “And what was it?”

“Well, I didn’t know what it was when I first saw it,” Schmidt continued, “but it certainly looked like some things I had seen before. I think we both immediately saw that cone shape and the kind of trail coming out of it, thinking that it could be an underwater volcano of a sort.”

Had it been anyone else, this might have been an invitation to head for the hills. But Schmidt is the regional geoscience specialist for the Tlingit and Haida Central Council. She’d been in Sitka for what has been a very interesting year – geologically – for the region. Her first impulse was to try and find the feature again, and then get on the phone.

“I’m aware of the geologic context of Sitka and the surrounding islands,” said Schmidt, “and spatially where the Queen Charlotte Fault is and where the Mt. Edgecumbe Volcanic Field is, and this location was just not adding up with the story that I know about our geology here. And so I just called the people who I knew had spent a lot of time thinking about the seafloor here.”

“It’s a classic example of what we have seen out on the (Queen Charlotte) Fault, down around Dixon entrance,” said Dr. Gary

Greene, one of the people Schmidt called.

Greene is a marine geologist, emeritus professor at the Moss Landing Marine Labs, and a leading expert on the undersea geology of the Queen Charlotte Fault.

“These types of plumes that come out of this volcanic-like cone are associated with what what we call mud volcanoes,” said Greene. “They’re not really active volcanoes, where magma comes flowing out, but it’s mainly fluids that come up from depth and carry with it sulfide-rich gasses and what have you.”

Greene has done sonar studies of the Queen Charlotte Fault that have produced images that are surprisingly similar to what Schmidt and her fishing partner saw on their depth sounder. The term “mud volcano” tends to conjure up thoughts of destruction, but – with a few exceptions – their only similarity to terrestrial volcanoes, like the nearby Mt. Edgecumbe, is their shape.

“If there’s a better term, I’d love to use it,” said Cheryl Cameron, “And right now, I don’t know about one.”

Cameron is a state geologist at the Alaska Volcano Observatory, and another expert Jacyn Schmidt consulted. Cameron is from Sitka, and is familiar with the depth sounders people use here while fishing. She hesitates to draw any conclusions from the image Schmidt captured, but admits that there are plenty of possibilities.

“A fishfinder is  looking for reflections within the water column,” she explained. “And so anything that has a density different from that of the rest of the water will cause a reflection. And so that reflector could be indicating a change in temperature or composition, it could be any kind of gas leaking out of the ground that would generate a plume with a different impedance, and thus a reflection. So it could be CO2 (carbon dioxide), it could be methane, it could be fluid with particulates in it –  there are a lot of possible causes that are not related to volcanism.”

Nakwasina, where Schmidt was fishing, is not within the Mt. Edgecumbe Volcanic Field – but it’s right next door. Edgecumbe generated headlines last spring when an earthquake swarm signaled that magma was stirring beneath the long-dormant crater. Subsequent radar studies showed that the flanks of the mountain had inflated by several inches over the last couple of years.  Although the mud volcano is probably not volcanic, Gary Greene says there’s not enough information to rule out that it might be related to what’s happening beneath Mt. Edgecumbe.

“It could very well be associated with that magma that’s moving up into the cone,” said Greene. “It could be that the heat from that magma has started a convection of warm or  hot waters that are now venting at that locality.”

The mud volcano is near a place called the Beehive. Everyone who’s been to Sitka on the ferry passes just a stone’s throw away. Jacyn Schmidt didn’t catch any halibut on the cone, but that unhappy fact hasn’t kept her away. Now, she’s fishing for information. 

“Well, we keep going back again,” she said. “My friend, whose boat I was on, has gone back to the same place to check again and again, and it’s still a bump under the water. I still have so many questions, and would like to go back with better instrumentation where you could really see but I’ll leave that to Gary and to Cheryl to direct.”

Although Schmidt is a professional scientist, accidentally discovering an underwater mud volcano is a form of citizen science that is very useful to researchers. Cheryl Cameron welcomes any and all observations of geologic phenomena at the Alaska Volcano Observatory. Gary Greene is going a step further, and looking for research funding to go down and take a look at the mud volcano, or at least take its temperature.

Marine geologist Dr. Gary Greene is in Sitka as part of his duties coordinating a project that has mapped in detail the Queen Charlotte Fault, specifically looking at the geometry of the fault, displaced seamounts, and implications for earthquake and tsunami hazards for coastal Alaska and communities like Sitka. The full schedule of his presentations can be found online at the Sitka Science Center.

A magnitude 4.3 earthquake struck about 30 miles southwest of Sitka shortly before 1:30 today/Monday (11-23-20). 

The earthquake’s epicenter was around fifteen miles deep. According to a statement from the National Tsunami Warning Center, there is no tsunami danger associated with this quake. 

Natalia Ruppert is a seismologist with the Alaska Earthquake Center in Fairbanks. She says the earthquake occurred on the Queen Charlotte Fault.  

We don’t detect smaller earthquakes [on the fault] because it’s farther away. Usually it has to be magnitude 3 so that the sensors on land are able to detect it,” she says. “But larger earthquakes are not as common. Last time we had a significant earthquake on the Queen Charlotte Fault was 2013.” 

The earthquake in January 2013 was a magnitude 7.5, located about 70 miles south of Port Alexander. That earthquake triggered a tsunami warning, forcing Sitkans and residents of surrounding communities to evacuate to higher ground, but only minimal sea level shifts were reported.  More recently, Sitka and most of coastal Alaska went under a tsunami warning in January 2018 after a 7.9 magnitude earthquake rumbled deep in the Gulf of Alaska. 

Ruppert asks that residents of Southeast Alaska who felt rumblings this/Monday afternoon report them to the Alaska Earthquake Center “Did you feel it?” webpage.

Editor’s Note: This story was updated at 4:17 p.m. with more information from the Alaska Earthquake Center.

Lindsay Worthington is a professor at the University of New Mexico in Albuquerque, NM. She and USGS geologist Maureen Walton are heading up a major project to study the undersea Queen Charlotte Fault system, which they call “The San Andreas of the Pacific.” The fault, which is offshore of Southeast Alaska, has had more frequent and larger seismic events over recent decades than its California cousin. The scientists spoke with KCAW’s Robert Woolsey about their work this summer.

Dr. Rachel Lauer was the Sitka Sound Science Center’s first fellow this year of its Scientists in Residence Fellowship, which brings scientists from all over the country to Southeast Alaska to collaborate with local scientists and present their research to Sitkans. (Photo courtesey of Rachel Lauer)

A geophysicist based in Canada was in Sitka for the month of October, learning how to better explain her work to people.

Dr. Rachel Lauer studies the subsurface movement of groundwater in the ocean floor — how it’s affected by the movement of geologic faults, and how it’s related to phenomena on land, like landslides.

Downloadable audio.

Every year, the Sitka Sound Science Center brings scientists from all over the country to Southeast Alaska through its Scientists in Residence Fellowship. The fellows stay for one month at a time and are given space to work and collaborate with the Science Center on their latest projects.

The latest scientific mind to come to Sitka through the program belongs to Dr. Lauer. She’s an assistant professor at the University of Calgary in the geophysics program that conducts research around the forces at play during earthquakes and tectonic plate movements.

Dr. Lauer’s research focuses on the processes that move and produce fluids below the sea floor, especially near faults like the Queen Charlotte system. Her expertise is in developing predictive models of fluid flow and using electrical resistivity to track the migration of gases in the subsurface.

Her Sitka residency was Dr. Lauer’s first look at the remarkable geology of Southeast Alaska.

“When you have this unique topography of mountains juxtaposed next to the ocean, you actually have the source of a lot of your groundwater here in the high elevation parts of the mountain that is actually hydraulically connected to the water that I study,” Dr. Lauer said.

Dr. Lauer said research on subsurface fluids can help us better understand what forces are at play when disasters like earthquakes and landslides hit, disasters like the 2015 landslide that killed three people in Sitka.

“This landslide is definitely tied to groundwater and fluids and fluid pressure,” she said.

The Science Center’s residency program also provides ample opportunities for scientists to engage with Sitkans and share their research in places like classrooms and – in Dr. Lauer’s case – whale-watching boats during WhaleFest.

Dr. Lauer said she doesn’t get to do that often enough and wishes academia would spend more time teaching scientists how to talk to non-experts. Most people don’t know much about the subsurface movement of fluids in the sea floor, but Dr. Lauer discovered that with the right approach, an audience will want to learn more.

“It turns out there’s a lot of different approaches you have to be cognizant of when you’re doing public talks,” she said. “Not everyone in the room has the same background.”

But according to Dr. Lauer, Sitkans make for a special kind of audience.

“It turns out in Sitka, there’s a lot of really bright and engaged citizen scientists which is really cool. I think there were 30 minutes of questions after my talk which never happens in academic settings.”

Although she hopes to expand her work someday into Southeast Alaska, for this visit at least, Lauer is taking newly-honed communication skills — rather than data — back to her colleagues in Calgary.

The largest dot indicates where the 4.3 magnitude quake struck, surrounded by smaller aftershocks. (Alaska Earthquake Center)

A series of earthquakes shook Southeast Alaska Monday afternoon into Tuesday morning. The epicenter of the quakes was located off the coast of Elfin Cove, 90 miles north of Sitka.

Natalia Ruppert is a seismologist at the Alaska Earthquake Center in Fairbanks. She said the series of quakes began with a magnitude 3.9 just before 12 p.m. Monday.

“This was not the largest from the Monday sequence, actually,” Ruppert said. “[A] magnitude 4.3 occurred about an hour after the 3.9 quake.”

After those initial quakes, Ruppert said, were a series of aftershocks in the same area. She said that’s typical, for one larger quake to be followed by smaller ones.

Another thing that’s typical is the location of the earthquakes.

“In Southeast Alaska there is a well-known fault called the Fairweather-Queen Charlotte Fault that follows the coastline of Southeast Alaska. It’s offshore,” Ruppert explained.

A fault is basically a fracture in the earth’s crust. Ruppert said, in the case of the Fairweather-Queen Charlotte Fault, the two sides are slipping past one another, creating earthquakes.

Monday’s 4.3 quake isn’t anything to be worried about, but Ruppert said the fault has slipped more severely in the past.

There was a magnitude 8.1 earthquake in 1949 and a magnitude 7.5 in 2013. The most notable quake in Southeast occurred the following summer in 2014.

“Maybe some people still remember on July 25, 2014 there was a magnitude 6.0 earthquake almost in the same location as the sequence on Monday,” Ruppert said.

According to Ruppert, the Alaska Earthquake Center hasn’t received reports from Elfin Cove or the surrounding communities after Monday’s earthquakes and aftershocks.

Even if you didn’t feel this one, though Ruppert likes to remind people that the fault is on the move.

“People in Southeast Alaska may forget that they live next to a major fault because they don’t feel these earthquakes very frequently, but it definitely should be on the back of their minds that this fault– Queen Charlotte Fault– is very active and it’s capable of producing major earthquakes so they should be aware and prepared,” Ruppert urged.

Monday’s magnitude 4.3 earthquake occurred around noon with ten aftershocks recorded through Tuesday. Ruppert expects those aftershocks to quiet down by Wednesday.

Researchers dropped seismometers from a ship in late April; the instruments settled onto the ocean floor along the Queen Charlotte – Fairweather faults, and recorded data for a month. (Photo courtesy of Emily Roland)

In January, a magnitude 7.5 earthquake shook up Southeast Alaska, and it sent scientists scrambling to study the fault where it originated before the seismic activity subsided.

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Emily Roland is a geophysicist with the US Geological Survey, based in Anchorage. In April, she and her team placed a dozen seismometers on the ocean floor, in a long line starting just below Baranof Island and stretching south for 100 miles along Southeast Alaska’s Queen Charlotte – Fairweather faults.

The goal was to record the aftershocks from January’s  earthquake – and the sensors, called seismometers, picked up something interesting.

“Whereas the land-based array recorded about five or so aftershocks that were magnitude 2.5 to 3,” Roland says, “We have recorded a lot more earthquakes that are much smaller magnitude.”

A lot more: about 500 earthquakes in the space of a month. These were small earthquakes, as small as magnitude .5. But even small earthquakes can tell researchers a lot. And right now, there are a lot of things scientists don’t know about the Queen Charlotte – Fairweather fault system, which runs just off the coast of Southeast Alaska and British Columbia. Roland says the fault is similar to its southern, much more famous, cousin, the San Andreas fault in California. But unlike the San Andreas fault, the Queen Charlotte fault runs primarily offshore, underwater and out of reach of sensors on land.

“In terms of basic research, and understanding how faults work, Southeast Alaska is a really exciting place to work,” Roland says.”There’s so many questions about the fault that we really don’t understand.”

Roland hopes the project will help researchers better map the fault system, and better predict what kind of earthquakes we might see in Southeast, how big those quakes might be, and where they might hit hardest.

One of the biggest questions is what kind of movement happens on the fault. The Queen Charlotte is primarily a strike-slip fault, where two plates are sliding past each other, grinding their surfaces together.

“I think of an earthquake as a quick failure, a quick slip that’s happening on a fault surface, between two surfaces of rock,” Roland says. Somewhere, there’s a crack in the rock, “but it’s locked in place by frictional forces. Shear stress along the plane eventually exceeds the strength of the rock, and it breaks very quickly” and that break is the earthquake.

But some parts of the Queen Charlotte system operate differently. They’re so-called thrust faults, in which one plate is being thrust up and over the other. That kind of movement caused A magnitude 7.8 earthquake in October, 2012 near Haida Gwaii. Roland wants to know if that kind of movement happens anywhere else in the system, in part because a thrust earthquake is more likely to cause a tsunami.

To figure this out, Roland and her team dropped the 12 seismometers down to the ocean floor. The instruments are sealed inside glass spheres, each about two feet wide, which are attached to an anchor, and dropped off the side of a ship.

“We really just drop them,” Roland says. “We set them up, we tell them what we want them to do, and we drop them off the side of the ship, and they sink.”

“Within a few hours of being deployed, they actually have a pretty interesting leveling device. The seismometer itself is contained within a box that has a kind of viscous fluid in there, and it has a little thing that unlocks itself, levels itself and locks itself again, so they’re kind of fancy in that regard.”

The seismometers have to be recovered after a month; the batteries only last that long. And that’s an adventure in and of itself.

“We go over the instrument with the ship, and we send some acoustic signals down to it, that tells it to release itself from an anchor,” Roland says. “The way that works is it sends voltage through a little filament, that causes the filament to burn, and disintegrate on the sea floor. Then a little hook raises itself, and the instrument releases itself from anchor, and becomes buoyant, and kind of slowly floats up to sea surface.”

It’s a complicated process, and a lot can go wrong.

“They’re small things,” Roland says. “They’re these little two-foot spheres in the big ocean…Everyone does a little thank you dance, I think, every time you really find one floating in the water and you’re able to recover it.”

Roland’s team recovered seven of the twelve. Another three have been found by people around Southeast, and two are still out there.

The project depended on the cooperation of the Coast Guard, which volunteered ship time.

“I’ve spent a good little bit of time working on large ships doing this type of work,” Roland says. “And of all of the crews I’ve worked with, I think the Coast Guard deck crews, I think they were the best.”

The Sitka-based Coast Guard cutter Maple helped deploy the instruments, while the Cordova-based Sycamore retrieved them.

Roland is now analyzing the data — and she hopes there will be plenty of earth-shaking discoveries to come.