Tag Archive: Alaska


Earth Watch Report Banner photo FSPEarthWatchReport900x228Blogger_zps53ef6af0.jpg

……………………………………………………………………………….

Sea otter  via Wikipedia,org

……….

October 09 2015 09:03 AM Biological Hazard USA State of Alaska, Homer [Kachemak Bay] Damage level Details

……….

RSOE EDIS  Event Report

Biological Hazard in USA on Friday, 09 October, 2015 at 09:03 (09:03 AM) UTC.

Description
An unusually high number of dead and dying sea otters have been found in the Kachemak Bay area near Homer this year. Staff from the Alaska SeaLife Center and experts from the U.S. Fish and Wildlife Service are working to figure out what’s killing off the otters at such a rapid rate. “More recently, animals have appeared otherwise healthy and seemed to have died very quickly,” said Dr. Carrie Goertz, the staff veterinarian at the SeaLife Center in Seward. “They are in good body condition, they have good weight, they have food in their stomach but they wind up dead on the shores.” According to Goertz, they’ve received four times as many reports of sick otters in the past month than they had the same time last year, bringing the 2015 total to more than 200. She said it’s typical to see a few die every year from a bacterial infection or trauma. Fish and Wildlife is waiting for test results from necropsies. One cause experts are looking into is the possibility of a toxic algal bloom that’s impacted some of the state’s shellfish farms. “Otters eat similar things that people eat, and so it’s a good idea to investigate that so we understand if it is a harmful algal bloom, if it might be affecting human food resources,” Goertz explained. The SeaLife Center’s newest sea otter pup is keeping stranding supervisor Halley Werner busy. Without his mom, he needs around-the-clock care. “They literally need to learn every single life skill from mom,” Werner explained. “Anything she hasn’t taught them before they come to us we need to teach them and make sure they’re able to take care of themselves.” The still-to-be-named pup is about five to six months old. He came to the facility three weeks ago after he was found with his dying mom on a beach near Homer. “It was really a sad scene. He was more or less guarding her, very fearful of what was going on,” Werner said. While experts work to determine a cause, Werner said her staff will be there to help save any otters they can. “We need to do our part of what we can here, caring for the live ones that we can help to recover and do well in an aquarium setting,” Werner said. “But it’s scary to know there’s something out there in the wild that we may or may not be able to do anything about.”
Biohazard name: Mass die-off (sea otters)
Biohazard level: 0/4 —
Biohazard desc.: This does not included biological hazard category.
Symptoms:
Status:

……….

Friday, 9 October 2015

Their silence is deafening! Experts are neither confirming or denying Fukushima as responsible for catastrophic deaths as sea otters are the latest species dying in record numbers

Sea otters are the latest species to add to the list of dying marine life and birds along the massive north American coastline stretching all the way from Mexico to Alaska.
Sea otters can now be counted along side fur seals, wales, walrus, dolphins, birds, fish, mussels and starfish dying in catastrophic numbers and the experts don’t know why……Or they do and they are not telling us!
It is very interesting experts are neither confirming or denying Fukushima as responsible for the catastrophic deaths!
An unusually high number of dead and dying sea otters have been found in the Kachemak Bay area near Homer this year.
Staff from the Alaska Sea Life Center and experts from the U.S. Fish and Wildlife Service are working to figure out what’s killing off the otters at such a rapid rate.

……….

Unusually high number of sea otter deaths reported in Kachemak Bay

By Heather Hintze 3:56 PM October 8, 2015

SEWARD –

An unusually high number of dead and dying sea otters have been found in the Kachemak Bay area near Homer this year.

Staff from the Alaska SeaLife Center and experts from the U.S. Fish and Wildlife Service are working to figure out what’s killing off the otters at such a rapid rate.

“More recently, animals have appeared otherwise healthy and seemed to have died very quickly,” said Dr. Carrie Goertz, the staff veterinarian at the SeaLife Center in Seward. ”They are in good body condition, they have good weight, they have food in their stomach but they wind up dead on the shores.”

According to Goertz, they’ve received four times as many reports of sick otters in the past month than they had the same time last year, bringing the 2015 total to more than 200.

 

Read More Here

……….

Earth Watch Report Banner photo FSPEarthWatchReport900x228Blogger_zps53ef6af0.jpg

………………………………………………………………………………

 

 Moderate World Earthquakes Magnitude 5–5.9

Moderate earthquake: M5.1 quake has struck near Nikolski in Alaska

8 Oct , 2015

Earthquake location 52.1137S, -171.8043W

A moderate earthquake magnitude 5.1 (ml/mb) has struck on Wednesday, 56 km SSE of Nikolski, Alaska (35 miles) The temblor was reported at 12:43:27/12:43 pm (local time epicenter) at a depth of 39.86 km (25 miles). Did you feel it? Was there any damage?

,

……….

9 earthquakes in map area
  1. M 4.8 – 40km WSW of Amatignak Island, Alaska 2015-10-08 13:23:01 UTC 51.7 km

  2. M 3.7 – 88km NNW of Talkeetna, Alaska 

    2015-10-08 12:33:49 UTC 129.7 km

  3. M 4.5 – 54km SSE of Nikolski, Alaska,

    2015-10-08 09:04:46 UTC 37.9 km

  4. M 2.6 – 160km S of Cape Yakataga, Alaska, 2015-10-08 06:08:43 UTC 33.8 km

  5. M 2.6 – 160km S of Cape Yakataga, Alaska 2015-10-08 04:35:21 UTC 9.2 km

  6. M 2.7 – 96km SSE of Old Iliamna, Alaska

    2015-10-08 02:03:30 UTC 124.6 km

  7. M 5.0 – 59km SSE of Nikolski, Alaska

    2015-10-08 00:05:56 UTC 30.8 km

  8. M 5.1 – 56km SSE of Nikolski, Alaska

    2015-10-07 23:43:27 UTC 39.9 km

  9. M 3.0 – 82km WSW of Cantwell, Alaska

    2015-10-07 22:48:32 UTC 113.5 k

……….

Earthquakes today

Earthquakes in Alaska

More earthquakes occur in Alaska than anywhere else in the United States. Alaska can have up to 24,000 earthquakes every year, according to the U.S. Seismology Department. Alaska is in the place where two major tectonic plates, continental and oceanic, bump into one another. It is the North Pacific Plate and the North American Plate that causes activity. Most of the activity happens in Cook Inlet, or north of Denali in the central region. The 1964 Alaskan earthquake, also known as the Great Alaskan Earthquake and Good Friday Earthquake, was a megathrust earthquake that began at 5:36 P.M. AST on Good Friday, March 27. Across south-central Alaska, ground fissures, collapsing structures, and tsunamis caused about 139 deaths. Lasting four minutes and 38 seconds, it was the most powerful recorded earthquake in U.S. and North American history. It had a moment magnitude of 9.2, making it the second strongest earthquake in recorded history.. Earthquakes in Alaska today. All information you need to know about Alaska. Find articles, news, videos, pictures, links and facts about Alaska. Alaska Earthquake latest breaking news and updates, information, look at maps, watch videos and view photos and more. Join the discussion on Facebook or Twitter and find more about temblor, tremor or quakes that have occurred in Alaska quakes. List of recent and latest earthquakes recorded in and close to this area today and now. We list magnitude, date, epicentral localization, maps, wave forms, the largest, tsunami hazards and last earthquakes in this state/area, Alaska.

……….

Alaska Earthquake Information Center

Link to Recent EarthquakesRecent Earthquakes

 

Magnitude and Age Legend for Earthquakes……….

Enhanced by Zemanta

M 6.1 – 138km NNW of Amukta Island, Alaska

 2014-02-26 21:13:40 UTC

Earthquake location 53.679°N, 171.837°W

Event Time

  1. 2014-02-26 21:13:40 UTC
  2. 2014-02-26 10:13:40 UTC-11:00 at epicenter
  3. 2014-02-26 15:13:40 UTC-06:00 system time

Location

53.679°N 171.837°W depth=264.7km (164.5mi)

Nearby Cities

  1. 138km (86mi) NNW of Amukta Island, Alaska
  2. 1371km (852mi) SSE of Anadyr’, Russia
  3. 1550km (963mi) WSW of Anchorage, Alaska
  4. 1578km (981mi) WSW of Knik-Fairview, Alaska
  5. 2321km (1442mi) W of Whitehorse, Canada

 

…..

Instrumental Intensity

ShakeMap Intensity Image

 

…..

Tectonic Summary

Seismotectonics of Alaska

The Aleutian arc extends approximately 3,000 km from the Gulf of Alaska in the east to the Kamchatka Peninsula in the west. It marks the region where the Pacific plate subducts into the mantle beneath the North America plate. This subduction is responsible for the generation of the Aleutian Islands and the deep offshore Aleutian Trench.

The curvature of the arc results in a westward transition of relative plate motion from trench-normal (i.e., compressional) in the east to trench-parallel (i.e., translational) in the west, accompanied by westward variations in seismic activity, volcanism, and overriding plate composition. The Aleutian arc is generally divided into three regions: the western, central, and eastern Aleutians. Relative to a fixed North America plate, the Pacific plate is moving northwest at a rate that increases from roughly 60 mm/yr at the arc’s eastern edge to 76 mm/yr near its western terminus. The eastern Aleutian arc extends from the Alaskan Peninsula in the east to the Fox Islands in the west. Motion along this section of the arc is characterized by arc-perpendicular convergence and Pacific plate subduction beneath thick continental lithosphere. This region exhibits intense volcanic activity and has a history of megathrust earthquakes.

The central Aleutian arc extends from the Andreanof Islands in the east to the Rat Islands in the west. Here, motion is characterized by westward-increasing oblique convergence and Pacific plate subduction beneath thin oceanic lithosphere. Along this portion of the arc, the Wadati-Benioff zone is well defined to depths of approximately 200 km. Despite the obliquity of convergence, active volcanism and megathrust earthquakes are also present along this margin.

The western Aleutians, stretching from the western end of the Rat Islands in the east to the Commander Islands, Russia, in the west, is tectonically different from the central and eastern portions of the arc. The increasing component of transform motion between the Pacific and North America plates is evidenced by diminishing active volcanism; the last active volcano is located on Buldir Island, in the far western portion of the Rat Island chain. Additionally, this portion of the subduction zone has not hosted large earthquakes or megathrust events in recorded history. Instead, the largest earthquakes in this region are generally shallow, predominantly strike-slip events with magnitudes between M5-6. Deeper earthquakes do occur, albeit rather scarcely and with small magnitudes (M<4), down to approximately 50 km.

Most of the seismicity along the Aleutian arc results from thrust faulting that occurs along the interface between the Pacific and North America plates, extending from near the base of the trench to depths of 40 to 60 km. Slip along this interface is responsible for generating devastating earthquakes. Deformation also occurs within the subducting slab in the form of intermediate-depth earthquakes that can reach depths of 250 km. Normal faulting events occur in the outer rise region of the Aleutian arc resulting from the bending of the oceanic Pacific plate as it enters the Aleutian trench. Additionally, deformation of the overriding North America plate generates shallow crustal earthquakes.

The Aleutian arc is a seismically active region, evidenced by the many moderate to large earthquakes occurring each year. Since 1900, this region has hosted twelve large earthquakes (M>7.5) including the May 7, 1986 M8.0 Andreanof Islands, the June 10, 1996 M7.9 Andreanof Islands, and the November 17, 2003 M7.8 Rat Islands earthquakes. Six of these great earthquakes (M8.3 or larger) have occurred along the Aleutian arc that together have ruptured almost the entire shallow megathrust contact. The first of these major earthquakes occurred on August 17, 1906 near the island of Amchitka (M8.3) in the western Aleutian arc. However, unlike the other megathrust earthquakes along the arc, this event is thought to have been an intraplate event occurring in the shallow slab beneath the subduction zone interface.

The first megathrust event along the arc during the 20th century was the November 10, 1938 M8.6 Shumagin Island earthquake. This event ruptured an approximately 300 km long stretch of the arc from the southern end of Kodiak Island to the northern end of the Shumagin Islands and generated a small tsunami that was recorded as far south as Hawaii.

The April 1, 1946 M8.6 Unimak Island earthquake, located in the central Aleutian arc, was characterized by slow rupture followed by a devastating Pacific-wide tsunami that was observed as far south as the shores of Antarctica. Although damage from earthquake shaking was not severe locally, tsunami run-up heights were recorded as high as 42 m on Unimak Island and tsunami waves in Hilo, Hawaii also resulted in casualties. The slow rupture of this event has made it difficult to constrain the focal mechanism and depth of the earthquake, though it is thought to have been an interplate thrust earthquake.

The next megathrust earthquake occurred along the central portion of the Aleutian arc near the Andreanof Islands on March 9, 1957, with a magnitude of M8.6. The rupture length of this event was approximately 1200 km, making it the longest observed aftershock zone of all the historic Aleutian arc events. Although only limited seismic data from this event are still available, significant damage and tsunamis were observed on the islands of Adak and Unimak with tsunami heights of approximately 13 m.

The easternmost megathrust earthquake was the March 28, 1964 M9.2 Prince William Sound earthquake, currently the second largest recorded earthquake in the world. The event had a rupture length of roughly 700 km extending from Prince William Sound in the northeast to the southern end of Kodiak Island in the southwest. Extensive damage was recorded in Kenai, Moose Pass, and Kodiak but significant shaking was felt over a large region of Alaska, parts of western Yukon Territory, and British Columbia, Canada. Property damage was the largest in Anchorage, as a result of both the main shock shaking and the ensuing landslides. This megathrust earthquake also triggered a devastating tsunami that caused damage along the Gulf of Alaska, the West Coast of the United States, and in Hawaii.

The westernmost Aleutians megathrust earthquake followed a year later on February 4, 1965. This M8.7 Rat Islands earthquake was characterized by roughly 600 km of rupture. Although this event is quite large, damage was low owing to the region’s remote and sparsely inhabited location. A relatively small tsunami was recorded throughout the Pacific Ocean with run-up heights up to 10.7 m on Shemya Island and flooding on Amchitka Island.

Although the Aleutian arc is highly active, seismicity is rather discontinuous, with two regions that have not experienced a large (M>8.0) earthquake in the past century: the Commander Islands in the western Aleutians and the Shumagin Islands in the east. Due to the dominantly transform motion along the western arc, there is potential that the Commander Islands will rupture in a moderate to large strike-slip earthquake in the future. The Shumagin Islands region may also have high potential for hosting a large rupture in the future, though it has been suggested that little strain is being accumulated along this section of the subduction zone, and thus associated hazards may be reduced.

East of the Aleutian arc along the Gulf of Alaska, crustal earthquakes occur as a result transmitted deformation and stress associated with the northwestward convergence of the Pacific plate that collides a block of oceanic and continental material into the North America plate. In 2002, the Denali Fault ruptured in a sequence of earthquakes that commenced with the October 23 M6.7 Nenana Mountain right-lateral strike-slip earthquake and culminated with the November 3, M7.9 Denali earthquake which started as a thrust earthquake along a then unrecognized fault and continued with a larger right-lateral strike-slip event along the Denali and Totschunda Faults.

More information on regional seismicity and tectonics

 

…..

 

Alaska Dispatch

Big 6.1 quake shakes Alaska in Aleutians:

 

A 6.1 earthquake shook the Alaska communities of Nikolski and Unalaska Wednesday, according to the Alaska Earthquake Center. The strong shake occurred around noon in the Bering Sea region of the state. The center says the earthquake had a preliminary magnitude of 6.1 and was located at a depth of 23 miles. The towns, located near the mid-section of the arc of the Aleutian Islands stretching more than 1,000 miles toward Asia, reportedly didn’t suffer any damages. Quakes with magnitudes of about 4.5 or greater are strong enough to be recorded by sensitive seismographs worldwide. Great earthquakes, such as Alaska’s 1964 Good Friday earthquake, have magnitudes of 8.0 or higher. The U.S. Geological Survey says that on average, one earthquake of that size occurs somewhere in the world each year.

 

…..

Enhanced by Zemanta

happy bear photo

CC BY 2.0 Beverly & Pack

Since the government shutdown got underway last week, the resulting furlough of federal employees and the closure of public land hasn’t been good news for anyone.

Well, except maybe for bears.

In Fairbanks, Alaska, the Bureau of Land Management (BLM) is responsible for routine maintenance on the grounds of White Mountains National Recreation Area. Due to recent furloughs however, those duties are now delegated to just two rangers remaining on staff. Not surprisingly, making sure all the trash bins along the park’s 1,000,000 acres are emptied on time has proven impossible for the pair.

Despite the shutdown, the sprawling recreation area has remained open for hikers, hunters, and other day-trippers. And while most of those visitors have been careful to safely dispose of their waste, it’s adding up to be a problem.

According to the Fairbanks Daily News-Miner, BLM ranger Jonathan Priday and his one remaining partner can’t keep up with all the trash. Now, opportunistic grizzly bears are clearly enjoying the fact that those formerly impossible-to-paw-open trash cans have been bested by squabbling in Washington D.C.:

Read More Here

Enhanced by Zemanta
LiveScience
 
frozen_forest
Stumps have been thawing from beneath the Mendenhall Glacier for about 50 years, but recently, considerably more have been found in upright positions with roots still intact.
Credit: Jamie Bradshaw

An ancient forest has thawed from under a melting glacier in Alaska and is now exposed to the world for the first time in more than 1,000 years.

Stumps and logs have been popping out from under southern Alaska’s Mendenhall Glacier — a 36.8-square-mile (95.3 square kilometers) river of ice flowing into a lake near Juneau — for nearly the past 50 years. However, just within the past year or so, researchers based at the University of Alaska Southeast in Juneau have noticed considerably more trees popping up, many in their original upright position and some still bearing roots and even a bit of bark, the Juneau Empire first reported last week.

“There are a lot of them, and being in a growth position is exciting because we can see the outermost part of the tree and count back to see how old the tree was,” Cathy Connor, a geology professor at the University of Alaska Southeast who was involved in the investigation, told LiveScience’s OurAmazingPlanet. “Mostly, people find chunks of wood helter-skelter, but to see these intact upright is kind of cool.”

The team has tentatively identified the trees as either spruce or hemlock, based on the diameter of the trunks and because these are the types of trees growing in the region today, Connor said, but the researchers still need to further assess the samples to verify the tree type.

A protective tomb of gravel likely encased the trees more than 1,000 years ago, when the glacier was advancing, Connor said, basing the date on radiocarbon ages of the newly revealed wood. As glaciers advance, Connor explained, they often emit summer meltwater streams that spew aprons of gravel beyond the glacier’s edge. [Images: Shrinking Alaska Glacier Spied from Space]

A gravel layer about 4 to 5 feet (1.2 to 1.5 meters) high appears to have encased the trees before the glacier ultimately advanced enough to plow over them, snapping off limbs and preserving the stumps in an ice tomb.

Read More Here

Enhanced by Zemanta
swat team photo swatteam_zps13878460.jpg
Composite created by Desert Rose Creations / Family Survival Protocol  2013

*********************************************************

Alaska Dispatch.

Gold miners near Chicken cry foul over ‘heavy-handed’ EPA raids

Sean Doogan

September 3, 2013

When agents with the Alaska Environmental Crimes Task Force surged out of the wilderness around the remote community of Chicken wearing body armor and jackets emblazoned with POLICE in big, bold letters, local placer miners didn’t quite know what to think.

Did it really take eight armed men and a squad-size display of paramilitary force to check for dirty water? Some of the miners, who run small businesses, say they felt intimidated.

Others wonder if the actions of the agents put everyone at risk. When your family business involves collecting gold far from nowhere, unusual behavior can be taken as a sign someone might be trying to stage a robbery. How is a remote placer miner to know the people in the jackets saying POLICE really are police?

Miners suggest it might have been better all around if officials had just shown up at the door — as they used to do — and said they wanted to check the water.

Lots of Federal land in Alaska

Alaska’s vast Interior, which sprawls to the Canadian border, has been the site of federal-local distrust in the past. It was near this area, 130 miles northwest of Chicken, that National Park Service rangers pointed shotguns at, then tackled and arrested a septuagenarian, for not stopping his boat in midstream of the Yukon River in the fall of 2010. Jim Wilde, 70 years old at the time, had been ordered to prepare to be boarded for a safety inspection.

Wilde didn’t much like that demand. He swore at park rangers and then headed for shore and a meeting on Terra Firma. Wilde was arrested and taken to the jail in Fairbanks, more than 100 miles away. He was later tried and found guilty by a federal magistrate for failing to comply with a lawful order from federal agents.

The state of Alaska, as a whole, can be a place of deeply-rooted mistrust between locals and the agents who try to enforce federal rules.

Alaska has more federally owned and managed land than any other U.S. state. More than 65 percent of its land is under some sort of federal control.  A multitude of federal parks, preserves and wilderness areas are patrolled by agents from more than a dozen U.S. agencies. Many of the people in rural parts of the state, which are either under federal control or border federally-managed areas, have more contact with federal officers than they do with representatives from the state.

Surprised by armed group of officers

Miners from the Chicken area — a gold mining town of just 17 full-time residents and dozens of seasonal miners off the Taylor Highway, between Tok and the Canadian border — said that during the third week of August they were surprised by groups of four to eight armed officers, who swarmed onto their mining claims with little or no warning.

The officers were armed and wearing body armor. They were part of the Alaska Environmental Crimes Task Force and were there to check for violations of section 404 of the Clean Water Act, according to several miners who were contacted by the group. Section 404 governs water discharges into rivers, streams, lakes and oceans.

The task force’s methods are now being questioned by the miners as well as the Alaska congressional delegation.

“Imagine coming up to your diggings, only to see agents swarming over it like ants, wearing full body armor, with jackets that say POLICE emblazoned on them, and all packing side arms,” said C.R. “Dick” Hammond, a Chicken gold miner who got a visit from the task force.

“How would you have felt?” Hammond asked. “You would be wondering, ‘My God, what have I done now?’”

Hammond and other Chicken area miners aren’t alone in wondering what they have done now. Both Alaska U.S. Sens. Lisa Murkowski and Mark Begich have inquired into the task force’s actions. Congressman Don Young is also looking into it. They have been having a difficult time getting straight answers from the EPA.

Rampant drug and human trafficking?

Read More Here

Enhanced by Zemanta

Earth Watch Report  –  Earthquakes

 photo Alaska-65MagEQSeptember3rd2013_zps06472214.jpg

M 6.5 – 77km SSW of Atka, Alaska

Preliminary Earthquake Report
Magnitude 6.5
Date-Time
  • 4 Sep 2013 02:32:33 UTC
  • 3 Sep 2013 14:32:33 near epicenter
  • 3 Sep 2013 20:32:33 standard time in your timezone
Location 51.592N 174.760W
Depth 39 km
Distances
  • 77 km (47 mi) SSW of Atka, Alaska
  • 1532 km (949 mi) SSE of Anadyr’, Russia
  • 1809 km (1121 mi) E of Petropavlovsk-Kamchatskiy, Russia
  • 1826 km (1132 mi) E of Yelizovo, Russia
  • 2618 km (1623 mi) W of Whitehorse, Canada
Location Uncertainty Horizontal: 11.3 km; Vertical 9.7 km
Parameters Nph = 105; Dmin = 78.2 km; Rmss = 0.85 seconds; Gp = 58°
Version = A
Event ID us b000jgju

For updates, maps, and technical information, see: Event Page or USGS Earthquake Hazards Program
National Earthquake Information Center
U.S. Geological Survey
http://earthquake.usgs.gov/regional/neic/

Instrumental Intensity

ShakeMap Intensity Image

M 7.0 – 94km ESE of Adak, Alaska

Preliminary Earthquake Report
Magnitude 7.0
Date-Time
  • 30 Aug 2013 16:25:03 UTC
  • 30 Aug 2013 04:25:03 near epicenter
  • 30 Aug 2013 10:25:03 standard time in your timezone
Location 51.711N 175.366W
Depth 34 km
Distances
  • 91 km (56 mi) ESE of Adak, Alaska
  • 1509 km (935 mi) SSE of Anadyr’, Russia
  • 1765 km (1094 mi) E of Petropavlovsk-Kamchatskiy, Russia
  • 1782 km (1104 mi) E of Yelizovo, Russia
  • 2642 km (1638 mi) W of Whitehorse, Canada
Location Uncertainty Horizontal: 12.7 km; Vertical 6.3 km
Parameters Nph = 140; Dmin = 93.8 km; Rmss = 1.07 seconds; Gp = 57°
Version = 7
Event ID us b000jdt7

For updates, maps, and technical information, see: Event Page or USGS Earthquake Hazards Program
National Earthquake Information Center
U.S. Geological Survey
http://earthquake.usgs.gov/regional/neic/

Instrumental Intensity

ShakeMap Intensity Image

  1. 5.4 77km SW of Atka, Alaska 2013-09-03 23:16:33 UTC-05:00 44.0 km

  2. 4.5 52km S of Tanaga Volcano, Alaska 2013-09-03 19:43:17 UTC-05:00 49.1 km

  3. 4.9 51km SSW of Tanaga Volcano, Alaska 2013-09-02 17:48:58 UTC-05:00 50.7 km

  4. 4.5 124km SE of Adak, Alaska 2013-09-02 16:07:17 UTC-05:00 24.9 km

  5. 4.7 119km ESE of Adak, Alaska 2013-09-02 10:54:48 UTC-05:00 35.0 km

  6. 4.6 94km ESE of Adak, Alaska 2013-09-02 04:59:03 UTC-05:00 52.5 km

  7. 5.2 100km SW of Atka, Alaska 2013-08-31 14:01:38 UTC-05:00 29.3 km

  8. 4.8 99km SW of Atka, Alaska 2013-08-31 13:59:53 UTC-05:00 39.1 km

  9. 5.2 100km SSW of Atka, Alaska 2013-08-31 05:06:14 UTC-05:00 26.1 km

  10. 5.0 105km SSW of Atka, Alaska 2013-08-31 04:54:13 UTC-05:00 25.1 km

  11. 5.2 97km SW of Atka, Alaska 2013-08-31 04:50:52 UTC-05:00 25.5 km

  12. 5.2 99km SSW of Atka, Alaska 2013-08-31 02:30:27 UTC-05:00 28.6 km

  13. 4.8 102km SSW of Atka, Alaska 2013-08-31 02:04:05 UTC-05:00 32.6 km

  14. 4.5 105km SSW of Atka, Alaska 2013-08-31 01:54:05 UTC-05:00 36.9 km

  15. 5.5 108km ESE of Adak, Alaska 2013-08-31 01:43:55 UTC-05:00 27.6 km

  16. 4.9 113km SSW of Atka, Alaska 2013-08-31 01:43:29 UTC-05:00 10.1 km

  17. 5.9 106km SSW of Atka, Alaska 2013-08-31 01:38:36 UTC-05:00 17.2 km

  18. 4.5 115km SSW of Atka, Alaska 2013-08-31 01:33:14 UTC-05:00 33.8 km

  19. 4.9 93km SW of Atka, Alaska 2013-08-31 01:31:09 UTC-05:00 26.4 km

  20. 4.5 103km SSW of Atka, Alaska 2013-08-31 00:18:37 UTC-05:00 28.8 km

  21. 4.8 97km SW of Atka, Alaska 2013-08-30 20:57:57 UTC-05:00 25.4 km

  22. 5.4 108km ESE of Adak, Alaska 2013-08-30 19:07:28 UTC-05:00 25.5 km

  23. 5.0 96km SW of Atka, Alaska 2013-08-30 16:55:42 UTC-05:00 25.4 km

  24. 4.6 88km SW of Atka, Alaska 2013-08-30 15:47:12 UTC-05:00 32.6 km

  25. 4.6 107km SSW of Atka, Alaska 2013-08-30 15:23:09 UTC-05:00 25.1 km

  26. 4.9 96km SSW of Atka, Alaska 2013-08-30 15:09:32 UTC-05:00 22.4 km

  27. 4.5 98km ESE of Adak, Alaska 2013-08-30 13:52:40 UTC-05:00 24.5 km

  28. 4.7 113km ESE of Adak, Alaska 2013-08-30 11:45:40 UTC-05:00 39.7 km

  29. 4.9 36km NNE of Akutan, Alaska 2013-08-28 19:54:56 UTC-05:00 112.4 km

Tectonic Summary

Seismotectonics of Alaska

The Aleutian arc extends approximately 3,000 km from the Gulf of Alaska in the east to the Kamchatka Peninsula in the west. It marks the region where the Pacific plate subducts into the mantle beneath the North America plate. This subduction is responsible for the generation of the Aleutian Islands and the deep offshore Aleutian Trench.

The curvature of the arc results in a westward transition of relative plate motion from trench-normal (i.e., compressional) in the east to trench-parallel (i.e., translational) in the west, accompanied by westward variations in seismic activity, volcanism, and overriding plate composition. The Aleutian arc is generally divided into three regions: the western, central, and eastern Aleutians. Relative to a fixed North America plate, the Pacific plate is moving northwest at a rate that increases from roughly 60 mm/yr at the arc’s eastern edge to 76 mm/yr near its western terminus. The eastern Aleutian arc extends from the Alaskan Peninsula in the east to the Fox Islands in the west. Motion along this section of the arc is characterized by arc-perpendicular convergence and Pacific plate subduction beneath thick continental lithosphere. This region exhibits intense volcanic activity and has a history of megathrust earthquakes.

The central Aleutian arc extends from the Andreanof Islands in the east to the Rat Islands in the west. Here, motion is characterized by westward-increasing oblique convergence and Pacific plate subduction beneath thin oceanic lithosphere. Along this portion of the arc, the Wadati-Benioff zone is well defined to depths of approximately 200 km. Despite the obliquity of convergence, active volcanism and megathrust earthquakes are also present along this margin.

The western Aleutians, stretching from the western end of the Rat Islands in the east to the Commander Islands, Russia, in the west, is tectonically different from the central and eastern portions of the arc. The increasing component of transform motion between the Pacific and North America plates is evidenced by diminishing active volcanism; the last active volcano is located on Buldir Island, in the far western portion of the Rat Island chain. Additionally, this portion of the subduction zone has not hosted large earthquakes or megathrust events in recorded history. Instead, the largest earthquakes in this region are generally shallow, predominantly strike-slip events with magnitudes between M5-6. Deeper earthquakes do occur, albeit rather scarcely and with small magnitudes (M<4), down to approximately 50 km.

Most of the seismicity along the Aleutian arc results from thrust faulting that occurs along the interface between the Pacific and North America plates, extending from near the base of the trench to depths of 40 to 60 km. Slip along this interface is responsible for generating devastating earthquakes. Deformation also occurs within the subducting slab in the form of intermediate-depth earthquakes that can reach depths of 250 km. Normal faulting events occur in the outer rise region of the Aleutian arc resulting from the bending of the oceanic Pacific plate as it enters the Aleutian trench. Additionally, deformation of the overriding North America plate generates shallow crustal earthquakes.

The Aleutian arc is a seismically active region, evidenced by the many moderate to large earthquakes occurring each year. Since 1900, this region has hosted twelve large earthquakes (M>7.5) including the May 7, 1986 M8.0 Andreanof Islands, the June 10, 1996 M7.9 Andreanof Islands, and the November 17, 2003 M7.8 Rat Islands earthquakes. Six of these great earthquakes (M8.3 or larger) have occurred along the Aleutian arc that together have ruptured almost the entire shallow megathrust contact. The first of these major earthquakes occurred on August 17, 1906 near the island of Amchitka (M8.3) in the western Aleutian arc. However, unlike the other megathrust earthquakes along the arc, this event is thought to have been an intraplate event occurring in the shallow slab beneath the subduction zone interface.

The first megathrust event along the arc during the 20th century was the November 10, 1938 M8.6 Shumagin Island earthquake. This event ruptured an approximately 300 km long stretch of the arc from the southern end of Kodiak Island to the northern end of the Shumagin Islands and generated a small tsunami that was recorded as far south as Hawaii.

The April 1, 1946 M8.6 Unimak Island earthquake, located in the central Aleutian arc, was characterized by slow rupture followed by a devastating Pacific-wide tsunami that was observed as far south as the shores of Antarctica. Although damage from earthquake shaking was not severe locally, tsunami run-up heights were recorded as high as 42 m on Unimak Island and tsunami waves in Hilo, Hawaii also resulted in casualties. The slow rupture of this event has made it difficult to constrain the focal mechanism and depth of the earthquake, though it is thought to have been an interplate thrust earthquake.

The next megathrust earthquake occurred along the central portion of the Aleutian arc near the Andreanof Islands on March 9, 1957, with a magnitude of M8.6. The rupture length of this event was approximately 1200 km, making it the longest observed aftershock zone of all the historic Aleutian arc events. Although only limited seismic data from this event are still available, significant damage and tsunamis were observed on the islands of Adak and Unimak with tsunami heights of approximately 13 m.

The easternmost megathrust earthquake was the March 28, 1964 M9.2 Prince William Sound earthquake, currently the second largest recorded earthquake in the world. The event had a rupture length of roughly 700 km extending from Prince William Sound in the northeast to the southern end of Kodiak Island in the southwest. Extensive damage was recorded in Kenai, Moose Pass, and Kodiak but significant shaking was felt over a large region of Alaska, parts of western Yukon Territory, and British Columbia, Canada. Property damage was the largest in Anchorage, as a result of both the main shock shaking and the ensuing landslides. This megathrust earthquake also triggered a devastating tsunami that caused damage along the Gulf of Alaska, the West Coast of the United States, and in Hawaii.

The westernmost Aleutians megathrust earthquake followed a year later on February 4, 1965. This M8.7 Rat Islands earthquake was characterized by roughly 600 km of rupture. Although this event is quite large, damage was low owing to the region’s remote and sparsely inhabited location. A relatively small tsunami was recorded throughout the Pacific Ocean with run-up heights up to 10.7 m on Shemya Island and flooding on Amchitka Island.

Although the Aleutian arc is highly active, seismicity is rather discontinuous, with two regions that have not experienced a large (M>8.0) earthquake in the past century: the Commander Islands in the western Aleutians and the Shumagin Islands in the east. Due to the dominantly transform motion along the western arc, there is potential that the Commander Islands will rupture in a moderate to large strike-slip earthquake in the future. The Shumagin Islands region may also have high potential for hosting a large rupture in the future, though it has been suggested that little strain is being accumulated along this section of the subduction zone, and thus associated hazards may be reduced.

East of the Aleutian arc along the Gulf of Alaska, crustal earthquakes occur as a result transmitted deformation and stress associated with the northwestward convergence of the Pacific plate that collides a block of oceanic and continental material into the North America plate. In 2002, the Denali Fault ruptured in a sequence of earthquakes that commenced with the October 23 M6.7 Nenana Mountain right-lateral strike-slip earthquake and culminated with the November 3, M7.9 Denali earthquake which started as a thrust earthquake along a then unrecognized fault and continued with a larger right-lateral strike-slip event along the Denali and Totschunda Faults.

More information on regional seismicity and tectonics

Enhanced by Zemanta
 
 

Earth Watch Report  –  Earthquakes


 photo Alaska-70MagEQaugust30th2013_zps846cbb49.jpg
 

M7.0 – 94km ESE of Adak, Alaska

 
 

Instrumental Intensity

ShakeMap Intensity Image

 

  1. 5.2 100km SW of Atka, Alaska 2013-08-31 14:01:38 UTC-05:00 29.3 km

  2. 4.8 99km SW of Atka, Alaska 2013-08-31 13:59:53 UTC-05:00 39.1 km

  3. 5.2 100km SSW of Atka, Alaska 2013-08-31 05:06:14 UTC-05:00 26.1 km

  4. 5.0 105km SSW of Atka, Alaska 2013-08-31 04:54:13 UTC-05:00 25.1 km

  5. 5.2 97km SW of Atka, Alaska 2013-08-31 04:50:52 UTC-05:00 25.5 km

  6. 5.2 99km SSW of Atka, Alaska 2013-08-31 02:30:27 UTC-05:00 28.6 km

  7. 4.8 102km SSW of Atka, Alaska 2013-08-31 02:04:05 UTC-05:00 32.6 km

  8. 4.5 105km SSW of Atka, Alaska 2013-08-31 01:54:05 UTC-05:00 36.9 km

  9. 5.5 108km ESE of Adak, Alaska 2013-08-31 01:43:55 UTC-05:00 27.6 km

  10. 4.9 113km SSW of Atka, Alaska 2013-08-31 01:43:29 UTC-05:00 10.1 km

  11. 5.9 106km SSW of Atka, Alaska 2013-08-31 01:38:36 UTC-05:00 17.2 km

  12. 4.5 115km SSW of Atka, Alaska 2013-08-31 01:33:14 UTC-05:00 33.8 km

  13. 4.9 93km SW of Atka, Alaska 2013-08-31 01:31:09 UTC-05:00 26.4 km

  14. 4.5 103km SSW of Atka, Alaska 2013-08-31 00:18:37 UTC-05:00 28.8 km

  15. 4.8 97km SW of Atka, Alaska 2013-08-30 20:57:57 UTC-05:00 25.4 km

  16. 5.4 108km ESE of Adak, Alaska 2013-08-30 19:07:28 UTC-05:00 25.5 km

  17. 5.0 96km SW of Atka, Alaska 2013-08-30 16:55:42 UTC-05:00 25.4 km

  18. 4.6 88km SW of Atka, Alaska 2013-08-30 15:47:12 UTC-05:00 32.6 km

  19. 4.6 107km SSW of Atka, Alaska 2013-08-30 15:23:09 UTC-05:00 25.1 km

  20. 4.9 96km SSW of Atka, Alaska 2013-08-30 15:09:32 UTC-05:00 22.4 km

  21. 4.5 98km ESE of Adak, Alaska 2013-08-30 13:52:40 UTC-05:00 24.5 km

  22. 4.7 113km ESE of Adak, Alaska 2013-08-30 11:45:40 UTC-05:00 39.7 km

  23. 7.0 94km ESE of Adak, Alaska 2013-08-30 11:25:02 UTC-05:00 33.5 km

************************************************************

Large earthquake hits remote Alaska waters, no tsunami seen

 
 
 

ANCHORAGE | Fri Aug 30, 2013 5:58pm EDT

(Reuters) – A large 7.0 magnitude earthquake struck early on Friday in waters 57 miles off the remote Alaska island of Adak, a former U.S. Navy station that is now a commercial fishing and maritime-service center, according to the U.S. Geological Survey.

There were no initial reports of damage, and the West Coast and Alaska Tsunami Warning Center said there was no tsunami watch, warning or advisory in effect.

“At this point, we’ve seen no ocean-surface disturbance,” said Bill Knight, a scientist at the tsunami warning center in Palmer, Alaska. While no tsunami was expected, he said scientists were still monitoring the area for any earthquake-induced waves.

The earthquake, which struck at 8:25 a.m. Alaska Daylight Time, was strongly felt in Adak, about 1,300 miles southwest of Anchorage, said City Manager Layton Lockett.

“It was kind of hard to miss,” Lockett said. “The strangest thing about this one was its length in time. I think people actually had time to get out of bed to see what was going on.”

A magnitude 7 earthquake is likely to produce shaking that lasts 20 to 30 seconds, although it could last longer depending on local tectonics, Knight said.

Read More Here

***********************************************************

Enhanced by Zemanta

Relocation of Alaska’s sinking Newtok village halted

Setback for tribal communities threatened by climate change as government freezes funding over local political dispute

Newtok, Alaska

An aerial view of Newtok, Alaska where the eroding bank along the Ninglick River has long been a problem for the village. Photograph: Al Grillo/AP

An Alaskan village’s quest to move to higher ground and avoid being drowned by climate change has sputtered to a halt, The Guardian has learned.

Newtok, on the Bering Sea coast, is sinking and the highest point in the village – the school which sits perched atop 20ft pilings – could be underwater by 2017. But the village’s relocation effort broke down this summer because of an internal political conflict and a freeze on government funds.

The Guardian wrote about the strains placed on Newtok by the erosion which is tearing away at the land, and at the villagers’ efforts to move to a new site, known as Mertarvik, in an interactive series in May.

Those tensions fed a rebellion against the village leadership, the Newtok Traditional Council, which had run the village for seven years without facing an election, and the administrator overseeing the relocation effort, Stanley Tom. His critics said he had botched the move to Mertarvik, and neglected the existing village.

Since October, Newtok residents voted repeatedly to elect a new roster of candidates to the council. They also tried to remove Tom. But the council refused to recognise the results, and Tom refused to step aside.

In July, the Bureau of Indian Affairs (BIA) took the unusual step of intervening in the internal dispute, and ruled the old council – which was working closely with Tom – no longer represented the villagers of Newtok. In an 11 July letter, Eufrona O’Neill, acting regional director of the BIA, noted the agency generally did not intervene in tribal political conflicts.

But she said the stand-off put the village at risk: “The continuation of a leadership vacuum would be detrimental to the best interests of the tribe, particularly in the present circumstances, where the community is in the midst of trying to physically relocate to a new village site due to serious erosion occurring at the present site.”

Read More Here

Enhanced by Zemanta