Discover and read the best of Twitter Threads about #earthquake

Most recents (24)

Watch the waves from the M8.0 Peru #earthquake roll across the USArray seismic network (usarray.org)! THREAD #PeruEarthquake
This animation, called a Ground Motion Visualization (GMV), shows the motion of the ground as detected on USArray seismometers - each dot is a seismic station and when the ground moves up it turns red and when it moves down it turns blue.
Earthquake waves travel around and through the earth, but they get smaller (attenuate) as they move away from the earthquake location, just like ripples in a pond.
Read 9 tweets
#Breaking: Just in - Northern country of #Peru was rocked by an 8.0-magnitude #earthquake, damage is to be expected.
#Update: Just in - Pictures coming out from #Peru when a 8.0 Magnitude shook north of the country showing damage. Picture Credit: @SergioPaulTandz
@SergioPaulTandz #Update: Just in - Video from #Peru when a 8.0 Magnitude shook north of the country showing damage and buildings collapsing. Picture Credit: @SergioPaulTandz
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Read 19 tweets
Seismic Shadow Zone - How do P & S waves give evidence for a liquid outer core? (THREAD) iris.edu/hq/inclass/ani… #earthquake #seismology @NSF_GEO
The concept of a seismic shadow zone as a global effect of an earthquake is an oversimplification that ignores a broad array of refracted, reflected and defracted seismic waves that propagate through the earth, as shown in this gif.
Let's focus on direct compressional P- and shearing S-waves. These are the body waves that take the most direct routes within the earth and create shadow zones.

An #earthquake sends P waves in all directions, refracting along boundaries with depth causing curving paths.
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Are you going to @NSTA? Please join us for one (or more!) of the following sessions or Share-A-Thons. #NSTA19 #educator (THREAD)
Thursday, April 11: Bring NASA’s Seismic Data from Mars to Your Classroom!
3:30–4:30 PM | America’s Center, Room 242
Explore data from the first seismometer on #Mars! Learn about Mars’ interior using IRIS’s free software, lessons, and data from @NASAInSight mission. #NSTA19
Friday, April 12: Meet Me in the Middle Share-a-thon
3:00–4:30 PM | Marriott St. Louis Grand, Majestic D/E @NSTA #NSTA19
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The Great Alaska Earthquake occurred on March 27, 1964 and rocked the state with strong ground shaking that lasted four and a half minutes. #AlaskaEarthquake #earthquake
At M9.2, it was the 2nd largest quake ever recorded. This event also rocked the scientific community by confirming a major principle of #platetectonics with the observation that the oceanic Pacific Plate dives beneath the continental North American Plate at the Aleutian trench.
On average, #Alaska has 24,000+ measured earthquakes every year. Usually, there is at least one M7 every year. Between 1899 and 1986, eight #earthquakes of M8 or greater impacted different areas of the Aleutian subduction zone.
Read 19 tweets
Spending the morning at the National Press Club for the “Science During a Crisis” event. Interested to hear about the new report and the call to action. #science
Here the agenda
“Science has a key role to play in the immediate hours after a crisis.” - David Oxtoby
Read 20 tweets
Subduction-zone mega-thrust #earthquakes, the most powerful earthquakes, can produce #tsunamis through a variety of structures that are missed by simple models. (THREAD)
The basic model shows rock above the convergent plate boundary being compressed and bent as it stores elastic energy. Once friction is overcome, the overriding plate slides abruptly up the fault causing the leading edge to heave seawater upward generating a #tsunami.
In 2011, the M9 #Japan #earthquake ruptured a fault area 500kms x 200kms over an interval of nearly 3 min. Surveys of sea-floor bathymetry before and after the earthquake document up to 50 m of fault displacement at near the Japan Trench.
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Hi @GlenPhillips and @ToadWetSprocket! You asked me a question about #earthquakes in the PNW at one of your shows DC in Aug (that’s me in the @500womensci shirt). I’ve finally got a more complete response for you! (THREAD)
The Pacific Northwest is a region of high #earthquake risk because of megathrust earthquakes on the plate boundary, deep earthquakes within the subducting plate, and shallow crustal earthquakes.
Along the western edge of the PNW, the Juan de Fuca Plate dives beneath the margin of the North American Plate in a process called subduction. On Jan 26, 1700 a M9 earthquake ruptured the full 1,000 km length of that plate boundary.
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NEW ANIMATION! Foreshock, Mainshock, or Aftershock? (THREAD) #earthquake @NSF_GEO
There is often confusion surrounding the terminology of earthquakes. Large earthquakes are followed by 100s or even 1000s of smaller earthquakes, called aftershocks. In some #earthquake sequences, a smaller earthquake called a “foreshock”, precedes the mainshock.
Although seismologists have carefully analyzed foreshock/mainshock pairs of earthquakes, and earthquake triggering in general, there are no special characteristics of a foreshock that let us know it is a foreshock until the mainshock occurs.
Read 12 tweets
Japan has more measurable #earthquakes than any other country. This is because #Japan is wedged among four major tectonic plates. (Thread)
80% of earthquakes worldwide occur around the circum-Pacific region chiefly along the subduction-zone boundaries, known as the “Pacific Ring of Fire”, so named because of the more than 400 active volcanoes that occur there.
The earthquake and volcano belt sweeps through Japan where about 20% of worldwide measured earthquakes occur. There are more than 100,000 earthquakes recorded in Japan every year. Of those about 1,500 are strong enough for people to notice.
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M 4.4 - 11km NNE of Decatur, Tennessee earthquake.usgs.gov/earthquakes/ev…
These colored lines show the intensity of ground shaking from the #earthquake. How hard the ground shakes is related to the magnitude of event, the distance from the event and the local geology earthquake.usgs.gov/earthquakes/ev…
So far, 6000+ people have reported feeling this #earthquake via the @USGS. Did you feel it? Let them know 👉 earthquake.usgs.gov/earthquakes/ev…
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I just got sent home from work after a massive earthquake in Anchorage, #Alaska :
Read 11 tweets
(1) #Earthquake near #Anchorage, Alaska in the last hour.

Moderately deep & strong, expect some damage, but loss of life unlikely. Magnitude is usually downgraded from initial level.

Best info source:

earthquake.usgs.gov/earthquakes/ev…
(3) Some photos from around Anchorage that I've seen on Twitter. In New Zealand we have an earthquake of this type about once or twice a year. It is scary, but thankfully little damage is done.

#DropCoverHold is the best advice. More: ready.gov/earthquake
(4) If you feel an earthquake when you're on a beach or within a few miles of the coast, be aware of #tsunami risk.

"If it's long or strong, get gone." There is no time for warning sirens or messages.

If you don't feel it, that means any tsunami is hours away. You have time.
Read 36 tweets
Well that was a big earthquake
Chrissie is with the dogs. @QuinceMountain and I are in Wasilla, en route to my Iditarod rookie meeting, so we’re pretty close to the epicenter. Occasional aftershocks but we are a-ok.
Tsunami warning. Heading for high ground.
Read 19 tweets
Good morning from a UK with slightly less dull weather! I want to discuss two topics which are often confused & misunderstood, but first I wanted to clarify a few things from yesterday's threads #earthquake #Stress #faults 1/n
Referring back to the block diagram for dip-slip faults from yesterday, @CriticalStress_ noted that the stress arrows at the top were wrong. All faults have a confining (inward) compressional stress, but stresses from other directions can be larger 2/n
This diagram from @SEELeeds shows that in the example block diagram I gave the smallest stress (sigma-3, min) is inward perpendicular to the fault. The primary stress - the largest amount of force acting on the rock to produce a normal fault - is vertical: GRAVITY! 3/n
Read 31 tweets
This is a most odd and unusual seismic signal.
Recorded at Kilima Mbogo, Kenya ...
#earthquake
earthquake.usgs.gov/static/earthqu…
and here at Lusaka, Zambia ...
earthquake.usgs.gov/static/earthqu…
and at Mt. Furi, Ethiopia ...
earthquake.usgs.gov/static/earthqu…
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Video ini direkam langsung oleh teman yg berada di salah satu hotel saat detik-detik tsunami menerjang Palu. Durasinya gelombangnya terlihat tidak lama, kemudian air surut lagi.
Rekaman teman atas nama Junaedi. Alhamdulillah yg ngerekam selamat. Tadi malam lgsg bertolak dr Palu ke Mamuju via darat. Tiba sore tadi di Mamuju. Setelah dapat jaringan internet ngirim video ini ke group WA.
Footage detik-detik tsunami menerjang Palu. Direkam dari lobi utama Palu Grand Mal yang persis menghadap ke teluk (part 1)

#PrayForIndonesia #PrayforSulawesi #PrayforSulteng #PrayForPalu #PrayForDonggala #Earthquake
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(1) I survived a deadly #earthquake in 2011, so watching #hurricanes & other disasters has become a major interest of mine.

All I want is to help save lives & property.

The CA Democrats' reaction to their #wildfires crisis is very telling.

Many voters will #WalkAway.
(2) It's very simple to understand WHY California's #wildfires have worsened in the last 10 years or so.

Natural & plantation forests have been badly mismanaged. (Something we can change.)

Naturally occurring climate change is also a factor. (Something we can't change,)
(3) Democrats want you to ignore the factors we CAN change, such as the mismanagement of forests, & to focus on the factor we CAN'T change: The sun driving the cycle of warming & cooling that's gone on since the planet formed.
Read 18 tweets
#BREAKING : 7.0 magnitude #earthquake registered in the #Lombok region of #Indonesia, USGS says. abcn.ws/2AHLlVU
JUST in: #Bali rocked after 7.0 magnitude earthquake strikes #Indonesia's #Lombok Island, #tsunami alert lifted
fxn.ws/2Od5c0R
Strong shaking from the #Lombok earthquake has also been felt on the island of #Bali, a popular tourist destination @BNONews #PrayforLombok
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(1) Thread #2: Bridge Collapse - Live updates on Florida International University, (FIU) Miami bridge collapse.

Thread #1 (link below) reached 44 tweets on the first day, so it's time to start another.

(2) The above rendering of what the end product would have looked like shows the most obvious of the design flaws: a very wide span relying on overhead suspension cables for load bearing. Engineers apparently thought they could install all 950 tons without the cables.🤔
(3) This project was in the 8th of 9 years to completion. That's about standard for such a project. I think we're going to see that mistakes were made at every level of the process, by multiple institutions. Checks and balances did not work.

Florida has a big problem.
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24 years ago today the Northridge #earthquake (actually 2 near simultaneous 6.9 quakes) caused death & severe damage across Southern California. I lived in Burbank at the time and clearly recall feeling powerless against the forces of nature. #northridge
There's little warning for a quake (just enough to duck under a desk if you have a warning system like they do in Japan) and the damage is done almost all at once. So we establish tougher building codes, do drills, and train first responders.
Earthquakes like the Northridge quake are the result of pressure building up in fault lines that run all through Southern California and pretty much every where else in the world. (Even here in Florida, there's a huge fault just off the coast.)
Read 11 tweets

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