Earthquake rocks Alaska

Earthquake rocks Alaska


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The strongest earthquake in American history, measuring 9.2 on the Richter scale, slams southern Alaska, creating a deadly tsunami. Some 131 people were killed and thousands injured.

The massive earthquake had its epicenter about 12 miles north of Prince William Sound. Approximately 300,000 square miles of U.S., Canadian, and international territory were affected. Anchorage, Alaska’s largest city, sustained the most property damage, with about 30 blocks of dwellings and commercial buildings damaged or destroyed in the downtown area. Fifteen people were killed or fatally injured as a direct result of the three-minute quake, and then the ensuing tsunami killed another 110 people.

The tidal wave, which measured over 100 feet at points, devastated towns along the Gulf of Alaska and caused carnage in British Columbia, Canada; Hawaii; and the West Coast of the United States, where 15 people died. Total property damage was estimated in excess of $400 million. The day after the quake, President Lyndon B. Johnson declared Alaska an official disaster area.

READ MORE: The Deadliest Natural Disasters in US History


Earthquake Rocks Alaska, Generates Small Tsunami

ANCHORAGE, Alaska, January 23, 2018 (ENS) – A massive magnitude 7.9 earthquake struck off the Alaskan coast southeast of Kodiak Island in the Gulf of Alaska at 12:31 this morning, local time.

The center of the quake was located 175 miles southeast of Kodiak City. Scientists with the U.S. Geological Survey at first measured the quake at a magnitude of 8.2, but several hours later reduced that measure of strength to magnitude 7.9.

A tsunami alert was immediately issued from Alaska down the West Coast of North America to California and west to the Hawaiian Islands.

The tsunami alert activated emergency warnings around Alaska. Alerts were issued in coastal areas for residents to move to higher ground. Sirens roused residents of Kodiak and Homer, and people were evacuated from Sitka to Seward. There was no tsunami alert in Anchorage.

Map of the Pacific Ocean showing the earthquake location and its effect spreading south across the ocean (Map courtesy U.S. Tsunami Information System)

Two hours later the tsunami warning was still in effect for south Alaska and the Alaska Peninsula and Pacific coasts from Hinchinbrook Entrance, Alaska, 90 miles east of Seward, to Chignik Bay, Alaska.

A tsunami was generated by the quake, but waves never reached a height more than one foot. The coasts at Kodiak, Seward, Old Harbor, Sitka and Yakutat were affected.

All warnings, alerts and watches were canceled just after 4 am, and there were no reports of damage.

The U.S. Geological Survey says today’s earthquake occurred as the result of strike slip faulting within the shallow lithosphere of the Pacific plate.

At the location of the earthquake, the Pacific plate is converging with the North America plate at a rate of approximately 59 mm/yr towards the north-northwest.

The Pacific plate subducts beneath the North America plate at the Alaska-Aleutians Trench, about 90 km to the northwest of today’s earthquake, the USGS said.

The location and mechanism of today’s earthquake are consistent with it occurring on a fault system within the Pacific plate before it subducts, rather than on the plate boundary between the Pacific and North America plates further to the northwest, USGS scientists explained.

While commonly plotted as points on maps, earthquakes of this size are better described as slip over a larger fault area. Strike-slip-faulting events of the size of the January 23, 2018 earthquake are typically about 230 kilometers in length and 30 km in width.

Large earthquakes are common in the Pacific-North America plate boundary region south of Alaska. The USGS records show that over the preceding century, 11 other M7+ earthquakes have occurred within 600 km (400 miles) of today’s earthquake.

Most of these have occurred on the subduction zone interface between the two plates, to the north and northwest of today’s earthquake, including the M 9.2 Great Alaska earthquake of March 1964. The hypocenter of the 1964 event was located about 550 km to the north of the January 23rd earthquake, and the rupture of that event broke much of the shallow subduction zone interface over several hundreds of kilometers.

To the southeast of the Alaska Trench, two large (M 7.9 and M 7.8) strike slip earthquakes occurred in November 1987 and March 1988, respectively, several hundreds of kilometers to the east of today’s quake.

© 2018, . Environment News Service (ENS) © 2021 All Rights Reserved.


Earthquakes are not isolated events, they occur in sequences. Most often, each sequence is dominated by an event with a larger magnitude than all others in the sequence (usually about one magnitude unit larger).

We call the large event the mainshock, and the events that follow are called aftershocks.

Occasionally, the mainshock is preceded by an event or events that we call a foreshock(s).

Sometimes, earthquakes occur in interesting sequences which we call doublets, triplets, multiplets, or swarms depending on how many similar-size events are in the sequence.


Earthquake Rocks Central Alaska

ANCHORAGE, Alaska (AP) _ A major earthquake rocked a sparsely poplulated area of interior Alaska on Sunday, knocking over fuel tanks, damaging highways and shaking up rural homes.

The magnitude 7.9 quake, centered 90 miles south of Fairbanks, was strongly felt in Anchorage about 270 miles to the south. It hit at 1:13 p.m Alaska Standard Time, said Bruce Turner of Alaska Tsunami Warning Center.

``It shook for a good 30 seconds,″ he said. It did not generate a tsunami, he said.

KCAM-radio in Glennallen reported that fuel tanks in the Interior village of Slana were tipped over and that nearby highways suffered damage.

Paul Whitmore of tsunami warning center said the highway between Anchorage and Fairbanks was damaged and Alaska State Troopers had closed the road to one lane.

Jill Woster said she was driving between Fairbanks and her home in North Pole when the quake began.

``The car felt like it was going to fall apart,″ she said. Woster arrived home to find pictures off the walls and on the floor, along with glassware.

Earthquakes above magnitude 7 are considered major _ capable of widespread, heavy damage.

The ``Good Friday″ earthquake in Alaska that left 131 people dead in 1964 measured 8.5 on Richter scale. Current measures put the magnitude at 9.2.


How Alaska Formed

Alaska is a jigsaw puzzle of related rock packages, or terranes, placed together over time through the movement and creation of earth materials along faults as tectonic plates drift away from, or run into, each other. Much of Alaska's bedrock is now metamorphic rock that has been deformed under heat and pressure as it was buried under the Earth's surface. Most of Alaska's oldest rocks are approximately one billion years old, although Alaska's oldest known rock is about two billion years old. New earth materials are born from volcanoes, such as along the Aleutian Arc, recycled into sediments from weathering processes, and lithified from sediments into new rock.

The older metamorphic rocks of Alaska may be broadly simplified into three categories, separated spatially by faults. Many of the faults are recently active:

(1) Metamorphosed continental margin rocks (mostly marine sedimentary rocks) adjacent to the ancestral North American plate and related rocks are found in Alaska's Interior, between the Tintina and Denali fault systems.

(2) Metamorphosed marine and marginal sedimentary rocks, carbonate platform, oceanic igneous (ocean crust) rocks, and volcanic rocks comprise western and northern Alaska, north of the Tintina fault system. These rocks came together during uplift and deformation resulting from the opening of the Canadian Basin (which became the Arctic Ocean), beginning about 150 million years ago.

(3) The variably metamorphosed arc-related volcanic, oceanic, sedimentary, and plutonic rocks of south-central and southeast Alaska have slipped up along the Denali and more southerly fault systems from the southeast over the last 120 million years.

During Alaska's dynamic past, Alaska was enriched in significant resources of minerals and oil and gas. Each group of related rocks has a unique and complicated history, which ensures DGGS geologists conducting research in Alaska or exploring for resources are intrigued and hard at work unraveling their origins.


Alaska earthquake rocks reveal anchorage buildings, buckle roads, stunning movies and images

A powerful 7.0 magnitude earthquake shook buildings – cracking dry stone walls and sending items off shelves – and buckled main streets in Anchorage on Friday morning. No injuries were reported.

Residents quickly turned to social media shortly after the seismic event to share shocking photos of the destruction, including collapsed ceiling tiles, streets buckled up, and materials in messed up houses. One picture showed a car stranded on a paved island and surrounded by cavernous cracks where the earthquake parted the road.

“This earthquake cut my school in half,” tweeted Josh Bierma, a student in Anchorage.

LARGE ALASKA EARTHQUAKE JOLTS RESIDENTS, SHAKES BUILDINGS

An Anchorage newscaster shared a picture of overturned chairs and wooden planks spilling onto the floor.

“”[The] The newsroom felt the blow of the earthquake this morning, “said KTVA reporter Cassie Schirm, noting that there was no electricity on the east side of the city.

Cereal boxes and battery packs lay on the floor of a grocery store, and picture frames and mirrors were thrown from the living room walls.

“It was anarchy,” Brandon Slaton, a resident of nearby Kenai, Alaska, told The Associated Press.

Anchorage Police Chief Justin Doll reported reports that portions of a scenic freeway leading from Anchorage towards mountains and glaciers have sunk and “completely disappeared”.

Here’s a look at some of the Destruction Dwellers who have shared online so far.

Fox News’ Greg Norman and The Associated Press contributed to this report.


'Like a freight train': Massive earthquake rocks Anchorage, Alaska

A massive earthquake -- registering 7.0 magnitude according to the U.S. Geological Survey -- rocked Anchorage, Alaska Friday, sending debris crashing to the ground, damaging buildings and causing "major infrastructure damage," officials said.

The quake happened about 7.5 miles north of the city, the USGS reported, and officials said residents there should brace for aftershocks. A tsunami warning was issued but later canceled.

Those caught in the tremblor described ferocious shaking that "just didn't stop." It was not immediately clear if there were injuries, but Anchorage police said damage was extensive.

"There is major infrastructure damage across Anchorage. Many homes and buildings are damaged," the department said in a bulletin. "Many roads and bridges are closed. Stay off the roads if you don't need to drive. Seek a safe shelter. Check on your surroundings and loved ones."

Dr. Owen Ala, 40, an orthopedic surgeon who was operating on a hand fracture at the time of the quake, said the quake sounded "almost like a freight train is coming through."

A lifelong Alaksan, Ala said that he's lived through a number of earthquakes before but this was the largest one yet.

"It definitely felt the strongest, not just by a little bit. It was by far the strongest that any of us had felt," he said.

"This one you could barely stand up," he said, noting how he and his team were "holding on to the patient to make sure they don't fall off the table."

The quake knocked out power to at least 21,000 customers, according to Chugach Electric, opened up gaping holes in roads and shook buildings like toys. CBS affiliate KTVA experienced extensive damage to its newsroom, the station said on its website.

The state's former governor, Sarah Palin, tweeted that her family's home sustained damage.

She posted a message that started with the prayer hands emoji, and went on to write "Our family is intact - house is not. I imagine that's the case for many, many others. So thankful to be safe praying for our state following the earthquake."

And President Donald Trump tweeted his support

Melody Blankenship, the business director at ABC affiliate KYUR, said that there was "this sudden shaking then all of a sudden this really loud roaring noise."

"It got to the point where we got into the doorway and it just didn't stop," Blankenship said.

She said that they felt an aftershock "not even five minutes later." She said that Friday's earthquake was "the strongest" she's felt in the past 35 years that she has lived in Alaska.

Dr. Lucy Jones, the founder of the Dr. Lucy Jones Center for Science and Society and a former scientist at the USGS, told ABC News that "it's a quite significant earthquake."

She said that the quake in Alaska was about the same size as the 1989 World Series earthquake in San Francisco, which caused landslides and widespread damage, and those in Alaska "would have felt the same sort of shaking."

One Twitter user posted a video from a local grocery store showing how shelved food was thrown onto the floor.

A student in Alaska posted a video on Twitter showing the lights in her art classroom shaking, and cupboards appear to have been opened due to the shocks.

"Earthquake just happened right now i 'm actually shaking," the student, Alyson Petrie, wrote.

The Anchorage School District posted a message to parents on their Twitter account.

"We hope that everyone is safe after the earthquake. We are assessing building safety and damages now. We will update the community as new information comes in. In the meantime, parents and guardians, when you feel it is safe to do so, please pick your children up from school," the school district wrote.


Monster Earthquake Rocks Anchorage, Alaska

A 7.0 quake that initially merited a now-rescinded tsunami watch.

A powerful earthquake struck the Anchorage, Alaska, area Friday morning. Early reports show a 7.0 rating on the Richter scale. No casualties have yet been reported.

A tsunami warning was issued in the surrounding areas, including the Cook Islands, but has now been rescinded. "There is NO tsunami danger from this earthquake," reads the latest message from the U.S. Tsunami Warning System.

While a welcome reprieve, early indications show that the earthquake has done substantive damage on its own. The Anchorage Police Department is referring to the event as "massive" and says that there is "major infrastructure damage across Anchorage. Many homes and buildings are damaged."

This is what happened on the 6th floor of the Nesbett Courthouse during the Anchorage #earthquake. Both attorneys jumped under their desks. Evacuated the building after the shaking stopped. pic.twitter.com/dqHGPCv6XO

&mdash Heather Hintze (@HeatherHintze) November 30, 2018

Power outages are popping up all around the Anchorage area. Chugach Electric Association, a utility that provides much of electricity in Anchorage, is reporting on Facebook that approximately 21,000 customers are currently without power due to the quake. The utility is also publishing a map showing the real-time status of power outages in the area.

Due to the outages, FEMA is urging anyone wishing to make contact with loved ones in the area to reach out over social media and texts instead of traditional phone calls.


Rocks & Minerals

Alaska is a great place to pan for gold (the state mineral) and hunt for mineral and rock specimens. The state has a rich history of mining, due to its substantial endowment of mineral resources. The most important thing for you, as a prospector, to know is the ownership of the land on which you would like to rock hound. Landowners have different rules about what activities are permitted on their land. For example, the state has set aside specific areas for recreational gold panning:

Silver and copper mineralization in the Talkeetna Mountains. Green color is the copper mineral malachite. Photo credit: Evan Twelker, DGGS, taken 2014.

Prospecting and gold panning on state and BLM land is limited to hand tools and light equipment permits may be required for other equipment. For additional information about mining or mineral collecting on state land, view the Mining Resources web site or contact the Public Information Center. For information regarding mining on federal land, contact the Bureau of Land Management.

Without having to hike off the roads, specimens may also be viewed at the University of Alaska's Museum of the North, Alaska Museum of Science & Nature, and Chugach Gem and Mineral Society's Annual Rock and Mineral Show. DGGS also has a nice display of minerals, rocks, and fossils in its main Fairbanks office and many samples from all over Alaska are archived and viewable at the Geologic Materials Center.


Earthquake rocks Alaska - HISTORY

WHY EARTHQUAKES HAPPEN IN ALASKA

From the dramatic Southeast coast to the heights of the Alaska Range and the volcanic islands of the Aleutians, earthquakes build the landscapes that drive Alaska’s rivers, glaciers, and even climate zones. Most of these earthquakes—and all major earthquakes—can be traced to the movement of tectonic plates.

The landmass beneath the Pacific Ocean is one of a few dozen tectonic plates that make up the earth’s crust. Each year, the Pacific Plate pushes a couple of inches towards Alaska, which is generally considered to be part of the North American Plate. Where these two plates meet, the dense oceanic rocks of the Pacific thrust under the more buoyant continental rocks of Alaska. This process is called subduction.

Subduction zone earthquakes follow the descent of the Pacific plate down to 200 km or more. Alaska’s largest earthquakes, exceeding magnitude 8 and even 9, occur primarily in the shallow part of the subduction zone, where the crust of the Pacific Plate sticks and slips past the overlying crust.

Examples of this type of earthquake include the 1964 magnitude 9.2 Good Friday Earthquake and the 1965 magnitude 8.7 Rat Islands Earthquake, the second and eighth largest earthquakes ever recorded worldwide.

Tectonics in Southeast Alaska are also driven by the movement of the Pacific Plate, but in a different way. As the plate inches toward the northwest, it grinds past Southeast Alaska and British Columbia. Unlike the subduction zone, these faults slip primarily in a side-to-side motion, with a different tectonic plate on each side. The earthquakes caused by this movement are shallow and occur primarily in the crust of the earth. This is a well-developed fault system that has been active for tens of millions of years and in historic times has hosted numerous earthquakes approaching magnitude 8. The 2013 magnitude 7.5 Queen Charlotte Fault Earthquake is a recent example.

Meanwhile, this northwest motion of the Pacific Plate exerts tremendous force on Alaska, compressing the land in a north-south direction and shearing or tugging southern Alaska to the west. The Alaska mainland is crosscut by numerous fault systems that accommodate this compression and shearing.

The vigor of these faults, and our knowledge of them, generally decreases toward the north, although the impact of this compression can be traced all the way into the Arctic Ocean.

The resulting seismicity is remarkable for its variety and geographic reach: events like the 2002 magnitude 7.9 Denali Fault Earthquake, and the 1958 magnitude 7.3 Huslia earthquake, as well as the highly active Minto Flats Seismic Zone, all result from this powerful compressional force.

However Alaska can also produce earthquake swarms, or a series of earthquakes that is not similar to your typical mainshock-aftershock sequence. It is still uncertain as to exactly why swarms occur, but they occur around the state and can vary in magnitude, quantity, and duration. In 2014, a swarm near Noatak rattled residents with five magnitude 5.3-5.7 earthquakes spread out over two months. In 2015, a swarm off St. George Island shook the normally quiet Pribilofs. And in 2018, a swarm in the eastern Brooks Range accounted for more than 2,000 of the year's record 55,000 earthquakes in Alaska.

HOW MANY AND HOW LARGE?

The Earthquake Center detects an earthquake every fifteen minutes, on average. In 2018, we reported an all-time high of over 54,000 earthquakes in Alaska. As our monitoring network improves, we report more earthquakes because we are able to detect smaller earthquakes across more of the state. As the EarthScope Transportable Array project added new seismic stations in previously unmonitored areas, we noticed an upward trend of detectable earthquakes from around the state.

The subduction zone produces very large earthquakes—as large as anywhere in the world—including three of the twelve largest earthquakes ever recorded. Magnitude six and seven earthquakes can nearly happen anywhere in Alaska.

We reported over 220,000 earthquakes in Alaska over the last five years. Twenty-six of those had magnitudes of 6 or greater, and three had magnitudes of at least 7. Seventy-five percent of all earthquakes in the United States with magnitudes larger than five happen in Alaska.

WHAT WE DO ABOUT EARTHQUAKES

All Alaskans live with earthquake hazards. The Alaska Earthquake Center exists to minimize our risks by understanding where earthquakes occur and why. Tracking the earthquakes that occur each day provides clues about the earthquakes that are likely in the future.

When earthquakes do occur, rapid reporting allows the public and emergency managers to assess the potential impacts. By measuring the shaking across the region, and even in buildings, we are able to assess the potential impacts and determine what type of emergency response is likely to be most effective.

The breadth of our network—with monitoring stations located in cities, villages, and critical infrastructure from Southeast to the Bering Strait—demonstrates the reach of earthquake hazards as well as our commitment to minimizing those hazards for all Alaskans.


Watch the video: Σεισμός 8,2 ρίχτερ στην Αλάσκα!