Alaska on EARTH Magazine

Denali's Asian dinosaurs

Wed, 10 Jan 2018 09:37:53 -0500

“Paleontologists have long hypothesized that a land bridge between present-day Siberia and Alaska served as a gateway for fauna to migrate between Asia and North America during the Cretaceous, but they have unearthed little evidence that directly supports this idea. Now, researchers have found an Asian dinosaur track assemblage in North America, a discovery that backs the longstanding hypothesis.

Alaskan subduction zone mirrors Tohoku zone that unleashed tsunami

Thu, 09 Nov 2017 15:21:06 -0500

This diagram shows the generalized structure of the subduction zone off the Alaska Peninsula near the Shumagin Islands. A large normal fault cuts through the entire overriding North American Plate at a roughly 45-degree angle and connects to the megathrust fault along which the North American and Pacific plates move against each other. Credit: K. Cantner, AGI, based on data from Bécel et al., Nature Geoscience, 2017.

In 2011, a large swath of coastal Japan was devastated and more than 15,000 people were killed when the magnitude-9.1 Tohoku earthquake unleashed massive tsunami waves that inundated land with run-up heights of 30 meters in places. In a new study, researchers have discovered that the seafloor off the Alaska Peninsula exhibits structures and fault patterns similar to the region where the Tohoku quake originated — a finding that may indicate a higher tsunami risk for coastal Alaska than previously thought.

Ice (Re)Cap: November 2017

Wed, 18 Oct 2017 12:21:26 -0400

Jarvis Glacier flows from Mount Silvertip in the eastern Alaska Range. Runoff from mountain glaciers supplies water to streams and recharges aquifers in Alaskan watersheds. Credit: Anna Liljedahl.

From Antarctica to the Arctic; from polar caps, permafrost and glaciers to ocean-rafted sea ice; and from burly bears to cold-loving microbes, fascinating science is found in every nook and crevasse of Earth’s cryosphere, and new findings are announced often. Here are a few of the latest updates.

Down to Earth With: Alexander Stewart

Wed, 20 Sep 2017 13:32:05 -0400

Alexander Stewart. Credit: Alexander Stewart.

Sgt. Alexander Stewart was brought up to believe serving in the military was an obligation all young men should fulfill. In 1991, at the age of 17, he answered the call of duty and joined the U.S. Army, which took him to Alaska with the 6th Infantry Division (Arctic)(Light). The state’s endless snow and ice fascinated Stewart, and after he left active duty, he pursued a bachelor’s degree in geology. In 2007, he completed a doctorate at the University of Cincinnati — in glacial geology, of course. Now he teaches the subject at St. Lawrence University in New York.

Early spring thaw triggers Arctic greenhouse gas release

Tue, 14 Mar 2017 18:59:29 -0400

Researchers check on a gas flux measurement tower in Alaska after the annual spring thaw. Credit: Stan Wullschleger.

During the few short months of Arctic summer, plants and animals race to grow and reproduce, fueling the most active time in the Arctic carbon cycle. But in a new study, researchers examining one corner of the Arctic demonstrate that ecosystems in the icy north aren’t entirely shut down during the offseason, with pulses of carbon dioxide and methane released some years starting during the first spring thaw.

Benchmarks: July 9, 1958: Megatsunami drowns Lituya Bay, Alaska

Wed, 06 Jul 2016 08:53:09 -0400

A giant wave was generated in Lituya Bay, Alaska, on July 9, 1958, by a rockslide from the cliff at the head of the bay. The wave destroyed the forest over the light areas to a maximum height of 524 meters. The fishing boat Badger, anchored in the cove at lower left, was carried over the spit in the foreground. The Sunmore, near the bay's entrance, was sunk; the Erdie, anchored near the lower right, rode out the wave. Credit: U.S. Geological Survey.

The recent disaster in Japan demonstrates the incredible destructive power of a megatsunami in a heavily populated area. But a record-breaking tsunami of a different sort occurred in 1958, in a remote part of Alaska known as Lituya Bay — and was witnessed by only six people, two of whom died. The giant tsunami and the unusual geometry of the bay combined to produce the largest wave run-up ever recorded — deluging the steep forested hills along the edges of the bay to a height of 524 meters. The wave was a powerful reminder of the forces nature can unleash.

Buried sands tell of tsunami hazard from creeping megathrust fault

Mon, 16 May 2016 11:18:57 -0400

Thick sand deposits separated by dark bands of soil offered evidence of six tsunamis in the last 1,700 years at Stardust Bay on Alaska's Sedanka Island. Credit: Richard Koehler.

A slow-moving portion of the Alaska-Aleutian Megathrust Fault near Alaska’s Dutch Harbor appears more capable of generating sizable tsunamis than previously thought, according to a new study.

Fish evolved quickly after earthquake

Thu, 21 Apr 2016 16:10:05 -0400

A male three-spined stickleback. Credit: Mark Currey.

Evolution is often thought of as occurring over very long timescales, but as a tiny Alaskan fish demonstrates, significant changes can take place in just a few generations.

First all-digital geologic map of Alaska released

Thu, 21 Apr 2016 14:36:16 -0400

The Anchorage area is shown in this portion of the new digital geologic map of Alaska. The full map is available at https://pubs.er.usgs.gov/. Credit: U.S. Geological Survey.

When it comes to natural beauty, Alaska’s rugged, massive landscape is an embarrassment of riches, with towering mountains and lush forests, countless islands and a seemingly endless coastline. Below the surface, it features a wealth of interesting geology and abundant resources. Now, policymakers, land managers, scientists and the public can all explore Alaska a little more deeply with the recent release of the first-ever fully digital geologic map of the entire state.

Ice (Re)Cap: April 2016

Wed, 13 Apr 2016 17:09:04 -0400

Thawing permafrost in Alaska, which can lead to slope failures like this one along the Noatak River, may increase dramatically this century as air and ground temperatures rise. Credit: Rory Nichols.

Alaskan megathrust fault more active under Kodiak

Wed, 03 Sep 2014 08:12:33 -0400

This road along Womens Bay on Kodiak Island is in an area that subsided nearly 2 meters during the 1964 earthquake. Credit: U.S. Geological Survey Photographic Library.

In 1964, a magnitude-9.2 earthquake ruptured two segments of the Alaskan megathrust fault along more than 900 kilometers from Prince William Sound to Kodiak Island. Historical and paleoseismic evidence has hinted at previous events in this region in 1788 and about 1100, and now a team working on Kodiak Island has found clues of another large event that struck about 500 years ago. The find makes the recurrence interval for the tsunami-producing fault much shorter, potentially increasing the earthquake and tsunami hazard profile, not only for Alaska, but also Hawaii and California.

Augustine Volcano's earthquakes and explosive eruption caused by a clogged conduit

Mon, 28 Jul 2014 18:32:36 -0400

Augustine is one of Alaska's most active volcanoes. Credit: Game McGimsey, AVO/USGS.

Located 280 kilometers southwest of Anchorage, Augustine is one of the most active volcanoes in the volcanically active state, erupting every 10 to 20 years. Because of its history of frequent eruptions — five blasts in the past 75 years — and close proximity to Anchorage and other communities in south-central Alaska, Augustine is one of the best-monitored volcanoes in the state. “You can see Augustine’s ash clouds from Anchorage, so people really pay attention to it,” says Helena Buurman, a volcano seismologist at the University of Alaska in Fairbanks and lead author of the new study, published in Geophysical Research Letters.

Benchmarks: March 27, 1964: The Good Friday Alaska Earthquake and Tsunamis

Thu, 20 Feb 2014 12:02:22 -0500

Government Hill Elementary School in Anchorage was destroyed by the Government Hill landslide during the earthquake. USGS Photographic Library

During the Cold War, many Americans lived in fear of the day their town would be shaken by an atomic bomb blast. On Good Friday 1964, some Alaskans thought that day had come.

Tackling "Boundary Faults" across the Alaska-Yukon border: A report from the field

Wed, 04 Sep 2013 13:44:09 -0400

The group examining the Ruby batholith along the Alaska Highway near Beaver Creek, Yukon. Melanie Werdon, DGGS

Our two dusty trucks roll across the airstrip, casting long, late-May shadows down the runway. We spot our colleagues from the Yukon Geological Survey and realize we’ve found the right place after an exhausting 12-hour drive from Anchorage punctuated by several U-turns to find the right unmarked access driveway off the Alaska Highway at the south end of Kluane Lake. The evening air is crisp, and the towering peaks to the south are capped with snow. It’s 8:30 p.m., an hour later than we think (we crossed a time zone at the Alaska-Yukon border) but still not dark, a benefit of being this far north in the late spring. We are happy to find pizza and, better yet, in the cooler, Yukon Gold beer.

Alaska's Mt. Redoubt erupts at last

Thu, 05 Jan 2012 06:41:58 -0500

Blogging on EARTH

After months of threatening and rumbling, Mount Redoubt finally erupted late Sunday night.

Redoubt began to exhibit increasing unrest last fall, with seismic activity becoming markedly increased in January, and expectations of an imminent eruption were growing. On March 15, researchers detected four hours of continuous volcanic tremor and observed of a brief plume of gas and ash, according to the U.S. Geological Survey's Alaska Volcano Observatory.

Scientists assess Redoubt's fury

Thu, 05 Jan 2012 06:41:58 -0500

After a series of five explosive eruptions from Sunday night through Monday morning, Alaska's Redoubt volcano quieted for about 15 hours Monday afternoon — long enough for scientists from the U.S. Geological Survey's Alaska Volcano Observatory to travel to the volcano to make observations and repair equipment (including the Redoubt webcam). A sixth explosive eruption followed Monday night at about 7:40 p.m.

Testing methane's potential on the North Slope

Thu, 05 Jan 2012 06:41:58 -0500

Sediment cores reveal hydrates (the white part of the core). An estimated 17 trillion cubic meters of natural gas as methane hydrates are stored beneath the North Slope. U.S. Geological Survey

In the Canadian Arctic, scientists are testing whether methane production through depressurization is feasible. U.S. Geological Survey

A chunk of methane hydrate. U.S. Geological Survey

One concern about depressurizing methane hydrates in the North Slope is that it could cause the marshy ground to collapse under the weight of production infrastructure. Dave Houseknecht, U.S. Geological Survey

Buried beneath the gigantic swath of desolate tundra that forms Alaska’s North Slope are some of the nation’s biggest hydrocarbon resources. For decades, the Trans-Alaska Pipeline has supplied about 20 percent of the nation’s oil. But below the permafrost of the Last Frontier lies another huge fossil fuel resource — and this one is a lot harder to tap.

USGS finds giant gas hydrate deposits on North Slope

Thu, 05 Jan 2012 06:41:58 -0500

Buried beneath Alaska's North Slope are about 85.4 trillion cubic feet of technically recoverable natural gas hydrates, according to a new U.S. Geological Survey assessment. That would be a significant source of energy to add to the U.S. energy mix — enough natural gas to heat 100 million homes for 10 years, Secretary of the Interior Dirk Kempthorne announced Wednesday.