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U.S. Earthquakes

  • A 2.7-magnitude earthquake on Tuesday morning was the latest to rattle part of Tennessee, geologists say.

    The tremor hit about 5 miles northwest of of Dyersburgat 12:35 a.m., according to the U.S. Geological Survey. People near the city of roughly 16,000told geologists they felt the quake, which was more than 7 miles deep.

    Some people in Dyer County, about 75 miles northeast of Memphis, reported feeling “weak” shaking, with no damage, according to the USGS.

    FEMA released the video below on tips on what people should do in the event of an earthquake.


    Read more here: https://www.newsobserver.com/news/nation-world/national/article239943558.html#storylink=cpy
     
    To the north and about one hour later, a 1.3-magnitude earthquake hit outside the town of Ridgely, geologists say.
     
    The quakes were the most recent in a swarm to hit Tennessee in the past month, records show.
     
    Eleven tremors have shaken the northwestern part of the state since Jan. 7, according to the USGS. The largest of those were 2.5-magnitude earthquakes, also hitting near Dyersburg and Ridgely last month, officials say.

    Quakes have also been reported nearby in Arkansas and Missouri, bringing the regional total to 29, records show.

    A swarm is a series of earthquakesthat are often small and linked to geothermal activity, the USGS says.

    “Swarms are usually short-lived, but they can continue for days, weeks, or sometimes even months,” according to geologists.

    In eastern Tennessee, seven quakes have hit this month, mostly in an area that’s more spread out, records show.

    The statewide total of 18 is down from this time last year, when the Volunteer State saw 27 quakes in a one-month period.

    Tremors of 2.7 magnitudehappen an estimated 30,000 times annually and are sometimes felt, according to Michigan Tech. They can also cause “minor damage,” geologists say.


    Read more here: https://www.newsobserver.com/news/nation-world/national/article239943558.html#storylink=cpy
     

    The quakes were the most recent in a swarm to hit Tennessee in the past month, records show.

     

    Eleven tremors have shaken the northwestern part of the state since Jan. 7, according to the USGS. The largest of those were 2.5-magnitude earthquakes, also hitting near Dyersburg and Ridgely last month, officials say.

    Quakes have also been reported nearby in Arkansas and Missouri, bringing the regional total to 29, records show.

    A swarm is a series of earthquakesthat are often small and linked to geothermal activity, the USGS says.

    “Swarms are usually short-lived, but they can continue for days, weeks, or sometimes even months,” according to geologists.

    In eastern Tennessee, seven quakes have hit this month, mostly in an area that’s more spread out, records show.

     

    The statewide total of 18 is down from this time last year, when the Volunteer State saw 27 quakes in a one-month period.

    Tremors of 2.7 magnitudehappen an estimated 30,000 times annually and are sometimes felt, according to Michigan Tech. They can also cause “minor damage,” geologists say.


    Read more here: https://www.newsobserver.com/news/nation-world/national/article239943558.html#storylink=cpy

    Read more here: https://www.newsobserver.com/news/nation-world/national/article239943558.html#storylink=cpy

    Read more here: https://www.newsobserver.com/news/nation-world/national/article239943558.html#storylink=cpy
  • A series of five earthquakes shook the state of Tennessee near the North Carolina border within a span of five hours.

    The earthquakes hit the Eastern Tennessee Seismic Zone, one of the most active areas in the southeastern U.S.

    The Southern Appalachian Seismic Zone, a seismic region stretching from northwestern Georgia, through Tennessee and into northeastern Alabama, was hit by a swarm of 5 earthquakes on February 11, 2020. The same area was struck by the seventh strongest quake in East Tennessee in more than a century on January 20, 2020.

    The five tremors occurred within 5 hours. Four of them were clustered around Greenback and one hit near Sweetwater. They were all under M2.0:

    • M1.7 @ 2:48 a.m. EST, 3 miles east of Greenback
    • M1.4 @ 3:23 a.m. EST, 1.2 miles northeast of Greenback
    • M1.6 @ 4:11 a.m. EST, 1.9 miles northeast of Greenback
    • M1.3 @ 6:06 a.m., 1.9 miles east of Greenback
    • M1.6 @ 6:56 a.m. EST, 5 miles east of Sweetwater

    Meanwhile, another M2.7 earthquake hit near Fincastle at 11:33 a.m. EST on February 12, 2020, which was reported by at least 40 people on the USGS homepage.

    Eastern Tennessee Seismic Zone (ETSZ)

    The Eastern Tennessee Seismic Zone (ETSZ) is one of the most active areas in the southeastern U.S. Its known faults are generally ancient and no known active faults reach the surface.

    The largest earthquakes in the ETSZ are the M4.6 in 1973 near Knoxville, Tennessee and the M4.6 on April 29, 2003 near Fort Payne, Alabama.

    However, the USGS has estimated that earthquakes as large as M7.5 are possible in the Southern Appalachian Seismic Zone.

    The source of seismic activity in the Eastern Tennessee Seismic Zone remains a mystery.

  • A M4.7 earthquake hit off the Oregon coast on February 8, 2020. It should remind us that an indescribable disaster in the offing is the Cascadia Subduction Zone earthquake, a scenario that involves a M9.0+ earthquake in the Pacific Northwest that would be felt all the way down to Northern California and would shake the earth for three to six minutes.

    The Pacific Coast would have perhaps an hour of warning before the tsunami hit. And the devastation would be great.

    If it happened tomorrow, there would be perhaps more than 10,000 deaths and 30,000 injuries. Whole cultures of people could be wiped out and the recovery would take decades. The good news? There’s probably ample time to prepare, and that preparation has begun. A similar quake is thought to have occurred in or before January 1700.

    Scientists estimate that a recurrence would be due in about 500 to 600 years. But they don’t know for sure. They also don’t know how much seismic slip occurred during that quake in 1700.

    Did the subduction zone save anything?

    Faults tend to be pretty good at this. They don’t always spend everything they have,” said Brian Atwater of the U.S. Geological Survey Earthquake Hazards Program. There may have been a lot of “breakage” during the last quake or there could be parts of the fault that didn’t break. That would be a way to get “better than 500 years’ worth of slip in 300 years,” Atwater said. Or maybe the earlier quake spent the “whole bank account” and the future event won’t amount to much.

    That’s part of the challenge of trying to present to a public audience scenarios for future earthquakes and their unknowns,” said Atwater. “They don’t happen like clockwork.

    Cascadia Rising: Alarming detail about the impending Cascadia earthquake and tsunami

    The document Cascadia Rising takes you through the scenario of The Quake. The daytime quake will sneak up on the region’s population, feeling somewhat like a semi-truck passing by.

    As the shaking continues, some will forget thei initial training. Some may run, but will make it only a few steps before falling. After about a minute, the shaking will begin to toss people about. Things not anchored will fall. Some people will have gotten under chairs, tables or something they think will protect them. Many will not.

    The document says that coastal areas will likely feel it the worst. But down in Oregon and even Northern California, residents will know something is afoot.

    Cascadia Earthquake Damage

    Besides the dead and injured, the damage to infrastructure would be enormous.

    One of the big threats during such a quake is liquefaction. Many critical structures stand on silt and sand that become unstable. The grainy soil will begin to act like liquid, and structures — such as bridges, ports, airports and industrial facilities — may shift position or sink.

    Local residents will have 20 to 30 minutes to get to high ground and away from the effects of the inevitable tsunami, which will consist of multiple waves over several hours. Some areas will remain flooded even as the tsunami retreats.

    There are complete cultures in Washington that could be completely wiped out. “It’s a catastrophic event that will affect a wide swath of our state and Oregon, British Columbia and Northern California,” said Paci-Green. “It is absolutely catastrophic for outer-coast communities, and beyond catastrophic for some of the tribes where a large percentage of their reservation is in the inundation zone.”

    The area will be prone to landslides and falling rock. The effect on transportation would be immense as the shaking and tsunami could damage 16,000 miles of highway and 7,000 highway bridges. The resulting economic losses could exceed $80 billion. 

    But those are estimates. Paci-Green said things could be worse. “The concern among the engineering community is that we don’t have a lot of data on how infrastructure, especially buildings and bridges, responds over that very long period of shaking,” she said. “We don’t know what we don’t know. The other fear is that these events are so far apart, that it’s much harder to get people’s attention and we’re only recently understanding the significance and the potential for a major Cascadia event.

    Preparedness Begins

    The immediate impacts will be devastating, but the bigger issue is long-term recovery. That means a consistent and sustained effort to build a more resilient community. “In terms of how to plan for this, it’s long term,” Paci-Green said. “Our best strategies for earthquakes and tsunamis are not response and preparedness, but mitigation, mitigation, mitigation. The six minutes of shaking are going to be really, really terrible. But it’s the decades of recovery that we actually need to be worried about.”

    As Paci-Green said, it’s difficult to develop a plan for something that may not happen for 100 years, but recent attention has sparked interest. “The risk is so overwhelming and so large, but also so infrequent that just the slow movement of mitigation is more likely going to put us in good stead,” she said.

    Washington is slowly seismically upgrading its bridges. Oregon is working on seismically upgrading its schools, and outer-coast communities are creating bonds and funding structures to do vertical evacuations or move critical assets out of inundation zones.

    Vertical evacuation is used when there’s no way to walk or drive out of the inundation zone. It consists of creating berms or multistory structures, strategically placed in communities where people can climb up and out of danger.

    Native Americans Preppers

    The Ocosta School District in Washington state is building a gym for vertical evacuation that will hold not only students and staff but also the local community.

    The Quileute Tribe, which is completely in the inundation zone, has spent the last 10 years fighting with the federal government about treaty boundaries and reservation boundaries, and was recently granted a land swap to be able to exit the inundation zone, according to Paci-Green.

    The Native American tribe is swapping with the federal government some of its reservation, which happened to be an access point to one of the state’s most scenic beaches, for about 750 acres of National Forest where its members can get to high ground. As a whole, tribes struggle to compete with other jurisdictions in the state when it comes to hazard mitigation grants funding and developing mitigation plans. “They’re very small jurisdictions and these kinds of tasks are overwhelming,” said Paci-Green. “At the same time, this is beyond catastrophic for the tribes because they may literally lose everything in their community.

    Paci-Green said the region needs to look at “innovative resilience solutions,” a lot of redundancy and also smaller-scale solutions such as developing local food production. “We may struggle to get food in across the mountains and up Interstate 5, and so more localized meeting of basic needs like food and water [is important].”

    Lots of Unknown

    The trouble is that scenario is not similar to the San Andreas Fault in California, where there’s a long history and considerable knowledge. “This is literally a new concept,” she said, “and our codes and planning and all that have not considered it for the vast majority of development in our communities, so we have a whole lot of small towns in the inundation zones.

    So When Will It Happen?

    Paci-Green said things are moving slowly and that’s OK. It’s best not to engineer a response based on fear. Plus, there’s time — but how much?

    The fault doesn’t have a good memory in terms of when the last event happened,” Atwater said. “So when the next one happens is independent of how much time has elapsed since the previous one.

    Most of the knowledge about the Cascadia Zone has been garnered relatively recently. “When I first showed up here in 1985, it was really a hot question among scientists as to whether this fault produces any earthquakes at all,” said Atwater. “And it’s only been during the past 30 years that a series of discoveries have been made that convinced earth scientists that it does pose a threat.

    The fact that the last one happened some 300 years ago makes it difficult for people to understand the potential. “The earthquakes that have happened in the last decades haven’t approached the kind of thing that the big faults are capable of doing,” said Atwater. “People don’t get the full sense of what nature can do. But that’s part of the detective story.” 

    This new moderate quake near the dangerous Cascadia should remind you of the earthquake risks you face if you live along the Pacific Northwest Coast. Because when the subduction zone explodes, it will be terrifying. So be ready and start to prepare for the next Big One… Just because it could hit tomorrow!

     

  • The quake hit at 2:12 p.m. (EST) or 1:12 p.m. (CST) in Campbell County and rattled people, homes and windows for a few seconds all across East Tennessee. Loud booms have also been reported across the area.

    The latest quake is tied for the seventh strongest earthquakes in East Tennessee in more than a century:

    • 4.7-magnitude in 1973 –  Alcoa
    • 4.5-magnitude in 1928 – Greeneville
    • 4.4-magnitude in 2018 – Decatur
    • 4.2-magnitude in 1987 – Vonore
    • 4.1-magnitude in 1956 – Claiborne Co.
    • 4.1-magnitude in 1913 – Grainger Co.
    • 3.8-magnitude in 1997 – Claiborne Co.
    • 3.8-magnitude in 2020 – LaFollette
    • 3.7-magnitude in 1995 – Monroe Co.
    • 3.7-magnitude in 1979 – Monroe Co.
    • 3.7-magnitude in 1984  – Corryton

    Meanwhile, a bit more than 10 hours after the big shaking, more than 10,000 people have reported feeling the tremor on the USGS homepage.

    Loud earthquake booms and rumblings have been reported:

    I was inside. It Sounded like a train getting closer. I felt like a train that was directly outside of my house. Suddenly I heard a big boom like it hit something. & it was over. Lasted maybe 15-20 seconds.

    Heard a loud deep rumble and then my doors and cabinets started rattling. Definitely took me by surprise and was a little frightening.

    The dogs started barking. It sounded like loud rumbling, the house was vibrating much more than if it had been a train or plane close by, and items hanging on the walls were shaking and making noise as they bounced off the walls. I noticed that noise before I realized the rumble was too strong for traffic/trains/etc.

     

    My wife said she thought something hit the house, and that the floor moved underneath her.

    We were upstairs at the time. My daughter was in her room. She felt significant shaking, heard cracking and popping, her light fixture was swinging, and her TV shook. My sister was in the bathroom. She heard a rumble sound, and felt a slight shaking and saw the mirror shake. I was in the central hallway, which is also our sitting room. I felt significant shaking, heard a low rumble, and the windows rattled somewhat noisily.

    The USGS estimates that earthquakes as large as magnitude 7.5 are possible in the ETSZ and that events of M5–M6 occur once every 200 to 300 years.

  •  

    On Feb. 24, two rare earthquakes were felt in Maine.

    A few hours later, 3 other quakes hit within the New Madrid Seismic Zone.

    both zones recorded minor but shallow tremors that were felt widely.

    2 earthquakes near Sabattus, Maine

    The two earthquakes were felt and heard by residents of Sabattus and nearby cities, around 6 p.m. on Sunday evening.

    The depth of the strongest quake was just over 3 miles and this also the reason so many people felt it, despite its M2.2.

    Maine sits in the middle of the North American Plate, which slightly moves every year. The motion puts stress on the entire crust of North America and when it is released, it creates some small earthquakes and rumbling noises like those people felt and heard around Sabattus, yesterday.

    3 earthquakes rattle the New Madrid Fault Zone

    Just a few hours later, 3 minor and shallow earthquakes also rattle the New Madrid Fault. 2 right in the ‘red zone’ of the fault line and one a bit aside.

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