Please LIKE and SUBSCRIBE. I also appreciate your continual support of these geology education videos. To do so, click on the three small dots (right of Download button above) then click on "Thanks") or you can go here: www.paypal.com/donate/?hosted_button_id=EWUSLG3GBS5W8 Or: www.buymeacoffee.com/shawnwillsey
Fantastic video. I was thinking just the other day how I wish I had been able to study geology when I was younger. Then you post videos like this and I feel like I’ve been given the chance again, thanks so much!
Really a great explanation of earthquake waves. In the late 60's I was in an Air Force organization monitoring for underground nuclear detonations. We used the seismic waves to identify and locate the sources of these detonations. Energy wise, even large detonations are very small compared to earthquakes. We primarily used the P and S waves to determine distance and magnitude. Distance was calculated based on propagation time between the P and S wave, and amplitude of the signals at that distance gave us an estimate of the magnitude. One thing that may help in understanding of the Raleigh surface wave (the second surface wave) is to describe it as a corkscrew pattern going through the earth's crust. In the 60's it was described as an elliptical retrograde motion. Because these waves move both horizontally and vertically in a circular motion, these waves result in cracks in an X pattern on the side of a vertical concrete walls, and are the more destructive of the surfaced waves.
I love this series you are putting together. I am not a student but I do find these very interesting. Getting under an IKEA desk, like most people have at home will probably not offer much protection, lol.
Thanks for this, Shawn. As a third-year geologist student, I experienced a mag 3.2 quake. We were in the top/ 4th floor geology lab when the building swayed alarmingly for a few seconds. In three years, none of us had been told that we were only a mile away from a fault line, running between the north coast of Wales and the island of Anglesey! That was 45 years ago but still memorable 🙂. I wish you and your family a happy, healthy and prosperous new year.
Watched the Mythbusters episode years ago where they built a house on a shake table and experimented with best place to take cover in an earthquake. And it was indeed under a sturdy table holding on.
I kind of taught myself what to do in an earthquake. 1983 Borah Peak earthquake. I ran outside. When I saw the power poles waving and the lines swinging I went…oh this isn’t the place to be! Went back in and stood in the doorway. Ok…now I know to get under a table or desk.
Thank you, Shawn, for another easy to follow video. I have always been fascinated by volcanoes and earthquakes since I was a child but you make it easy to understand and clarify what has been confusing for me in the past. I am looking forward to you making earthquake magnitude easy to comprehend as well.
Thank you for another great educational clip! We get intra plate earthquakes in Australia. Nothing like plate boundary quakes but they can still be a good shake when they come through. Last one we had in my area was 2015 and could hear the movement in the house.
I remember seeing a picture of a building in Mexico City that pancaked in a large quake, but you can see the desks holding up the floors, so there was a survivable space left.
Part of the Earthquake scenario in Emergency Management, CERT, Red Cross Disaster and First Aid/Wilderness First Aid et al training, is to (1) Get under a desk, table, or sturdy/heavy furniture, (2) Put your one hand and forearm over your head and neck, protecting you from bumping your head/neck with the furniture - let alone any falling objects, and (3) with the other hand hold onto the (movable) desk, table, or sturdy/heavy furniture keeping it in place, but also keeping you under furniture at all times.
@@Sinderbad Been there, done that. The reason they changed to this method - is that the desk, table, or furniture would shake and walk away from the covered individual and then they would get hit by falling debris. So they went for the 1 hand on head/neck, and 1 hand holding the desk, table, or furniture in place, or the person would crawl with the moving furniture !
The doorway myth, to the best of my knowledge, originated in my home state of CA where older building codes allowed for wider spacing (often 36" or greater) between beams in supporting walls, and very little cross-bracing. since doors are often around 30" wide the spacing of supporting beams was tighter, thus doorways were actually marginally more structurally sound. Codes were updated after the 1971 Sylmar EQ, and now require beams to be no more than 16" apart. Important to keep in mind that in non-residential buildings like schools and hospitals doors tend to be much heavier and can have much more inertia when swinging freely if left open.
The only reason I thought the doorway was accurate is because of the headers that support the weight of the walls above. Now that I actually have some knowledge that might be the best reason to NOT stand there.
Growing up in Los Angeles in the 60s and 70s and 80s feet, the official instructions for work for people to stand in a doorway during an earthquake. I know this has changed since I left LA. My brother-in-law was in San Francisco when the big one hit in 87. At that time, everyone was still being told to stand in the doorway. He found all of the doorways were full of people already when he got there.
I live in the New Madrid seismic zone... yes, that purple part in southernmost Illinois. Interestingly there is a fault system called the St. Genevieve (MO) fault that extends down into southern Illinois; it actually can be seen in aerial maps by those with keen eyes for that. The fault itself bisects my hometown (Anna) and the town next to it, Jonesboro.
The one EQ noted inside the African continent could be associated with the Great Rift that runs from Africa to Israel/Jordan, up into Turkey and Russia. This is the expanding earth rift of Ethiopia, that extends far south into this region.
The 1886 Charleston earthquake was a 7.0. Visitors today to the downtown peninsula can view “earthquake bolts” that literately “bolt” a house together in case of shaking from the Middleton fault. Come visit!
I experienced the 1989 Loma Prieta earthquake while living in the Bay Area. Its magnitude was eventually determined to be a 6.9. Of the many stories that stick with me about that event was from an interview with a student-athlete from Stanford University, whose campus was much closer to the epicenter in the Santa Cruz mountains. He said that the EQ began during Soccer practice (at 5:04 pm PDT). The players were 20-something-year-olds in peak shape, playing on a huge flat pitch -- arguably the safest place you could hope to find yourself during a big earthquake, with nothing but open space and nothing to fall on you -- but, in the panic they were all trying to run away to, well, anywhere. But they couldn't, because the horizontal shaking (S-waves + Love waves) made it impossible for them to stand and keep their feet underneath them. That's the story I try to get across to students about what they should do when an EQ begins. If it turns out to be a big, nearby event you have to assume that moving to a different location might just be impossible due to violent ground motion, so getting down low under a table or desk may be the only possible alternative.
This was great! I've lived in the SF Bay Area for about 20 years, so lots experience with smaller quakes, but it was great to understand them better. We actually heard a P-wave jiggle some paper once in Santa Rosa, about 5 seconds before we felt the shaking. We thought we had a mouse! Nope, just a P-wave.
In 1949 my mother and I were in Seattle waiting to board a passenger ship to go to Japan where my father was stationed. An earthquake struck and my mother and I stood in the doorway of the hotel we were in. My mother was born in Texas and as far as I know had never experienced a quake. I still remember watching the Murphy bed slam between open and closed.
I’ve felt at least 2 jolts in South Australia & Victoria, but they were really minor 2.0+. It was a little bizarre & what was that type of feeling! I remember 18 Dec last year & putting all devices on & frustrated with the fissure eruption as initially I couldn’t quite figure out the direction 😉
So, all these years, I thought I was feeling the P waves, but it's been the S waves. We have a lot in Humboldt, and I've grown accustomed to judging our earthquakes by that first felt jolt. Now I'll be looking for two before the real shaking starts 😂 Thank for the postings!
I grew-up in SoCal and automatically stand in the doorway if there's nothing to get under. Moved to Michigan and was in a cabin hit by a tornado. When the floor started shaking I went to the doorway... this is a really bad idea in a tornado.
When your phone tones and a USGS earthquake notification is received, activate the video camera on your phone and prepare to simulcast the event on social media….😜
For those of us who grew up in the early 1950s and remember “drop drills,” E was the immediate choice. Our teacher, with no warning, would yell “Drop!” and that we did, under our desks, curled up in a ball, facing away from windows, hands clasped behind our necks. For those who wonder why we did that, it wasn’t about earthquakes, it was about the fact that by then, the Soviet Union had nuclear weapons. And we had plenty of earthquakes in California’s San Fernando Valley, so sometimes we had that to contend with. Oh, and of course some guy always got one hand to his mouth to make fart noises and set everyone giggling.😂
At work one time we had a First Responder to earthquakes, foreign and domestic, come give a talk. He said they don't find people alive under desks and tables. They find people alive who are in voids created by the falling debris. Such as a roof beam held up by a wall. Of course it depends on the size of the quake, A small one where only the ceiling tiles fall you'll be good.
Back in my geology days we called surface waves “L” waves. During the Loma Prieta earthquake i was in Sacramento in a two story office building that looked out upon a basketball court. The waves were distinct and identifiable. I told the people sitting with me that that was a large quake, far enough away for the P,S & L waves to be segregated by the varying speed of each wave type.
18:17 My country The Netherlands has an increased risk due to an active normal fault in the southeast. in 1992 there was a damaging magnitude 5.8 quake on that fault and in 1932 a magnitude 5.0
But besides that, we have the quakes due to natural gas extraction in the northeast. I wonder if there is some explanation why, although those are usually below 2.5 magnitude, it absolutely freaks the inhabitants out. Is it only the fact that the country has little history in earthquakes, so we are not accustomed and not prepared (buildings are not constructed to be earthquake proof), or is there some other aspect to these quakes that makes them different from those caused by faults?
The P- and S-waves are very fast. Another wave of thinking about the speed these seismic waves is: * P-waves travel at about Mach 15 * S-waves travel at a little less than Mach 10 (ignoring the fact that Mach numbers don't make a lot of sense within solid rock!) The fastest airplane ever built - the SR-71 Blackbird or the less well-known A-12 Avenger - had a top speed of around Mach 3.4. The S-waves are more than *twice* that and the P-waves are *3 times* that.
Even small earthquakes can cause injuries. In 2015 a 4.1 struck north of where I live late in the evening while I was in bed. My cat used me as a launch pad in her haste to take cover. I had bloody claw marks on both legs. 😁
Question: Could one state that P waves are the actual rock movement, while S and Surface waves more akin to echoes ? ( a bit like thunder where the actual lightning is just a sharp bang, but further out, you hear echoes of that bang that reflect against clouds, and ground surface? )
Great information, Shawn. I love it, " . . . Eastern US . . . . " while pointing at the New Madrid fault system bisected by the Mississippi River. Spoken like an Idahoan such as myself who refers to anything East of Denver as "the East." I mentally pass right over the mid-west all the time. No offense intended. My first felt quake was 1978 in West Germany (courtesy of an Uncle Sam all expense paid 3 year trip), Salt lake in 1984, and 2020 again in Salt Lake. Wouldn't mind if I never experienced another.
My wife can feel those rarely felt waves. We were visiting Mt. St. Helens a few months ago. She asked if I felt anything I said no. She said she thought she did. We get back to our hotel I do a quick research for the time we were there & sure enough 2 small earthquakes did occur. They showed in 2.blah range.
Question. If you please Shawn. I am just watching a documentary on the 2011 Japan Magnitude 9 earthquake. It lasted for 10 minutes in some areas. How much earth movement actually occurred in metres etc to result in that magnitude 9?
Question: Not long ago, I heard that the Canadian Shield is not only very old, but very very old because we came from Rodinia (our part was then known as Laurentia) and Laurentia collected other bits to grow to North America during its travels to the northern hemisphere. is the north american plate considered a single plate today, or are there still geological "welds" where the different bits from its creation have fused? Would such "welds" present opportunities for earthquakes?
Yes, suture zones where crustal blocks have joined or even places where there were rifts will consist of faults. These older faults are weak zones that can be reactivated by tectonic stress and produce quakes.
I have a question about option E. earthquake response. Getting under a sturdy table, etc. What keeps the building from collapsing and falling in on you smashing you under the table, burying you under a pile of debris, possibly killing you? None of the options looked good to me.
Depends on where you are, but actual physical collapse of buildings during an EQ is quite rare, especially in areas with up-to-date building codes that are enforced. The biggest danger indoors is always from falling objects -- a sturdy table will give you good protection from that.
I am surprised that Hawaii is 3rd in the standing. Would have expected 2018 eruption with the frequent tremors from the collapse of Halemaʻumaʻu every 12 hours to have brought up to at least 2nd position. Or were those tremors less than the 3.5 for your statistics?
The the Laurentian mountains north of Montréal, there is Mont Trembant (known as highest mountain in the range but not sure if that is factual). It is at 46.22017745416989, -74.55292048013153. Tremblant = Trembling and it was named because of the first nations called it a devils's mountain because of the deep ground shaking noises they kept hearing. And there are relatively often some mild tremors there. (in a summer cottage, noticeble because structure shakes a lot !). Am curious on the origin of the earthquakes in the oldest mountain ranges in the planet, far awar from any continental plate boundary. Or are the earthquakes there average for north america, but the composition of ground makes it felt more by locals? (read that the area is gneiss).
with respect, option A is the best choice. hiding under a table may safe you from some falling objects, how nice, but this is not what you should be afraid of during an earthquake. smth falling on you hurts but doesnt kill you. earthquake are extremely "peaky" that is to say most dont really kill anyone untill one kills ALOT of people. this happens when buildings collapse, and a table will absolutely not save you. this is clearly born out of the numbers, just because schools teach smth else is irrelevant. if your worried about an auwie, hide if your worried about your life? run
Um I'm pretty sure that the quake in east Africa is a plate boundary between the African and Somalian plates it's a young plate boundary but the area is a divergent plate boundary. You also have a quake along another young boundary namely the reactivated ninety east lineament fracture zone in the Indian ocean the extinct mid ocean ridge of the Indian ocean where the Indian plate has recently separated from the Australian plate as a strike slip transform plate boundary composed of both left lateral and right lateral lineaments due to the differences in plate motion between India and Australia as the Australian plate is currently moving north at about twice the rate of the Indian plate. The quake in Mongolia is also notably near the Baikal rift zone where the Amur plate is in the process of detaching from Eurasia. The Amur plate is often lumped in with Eurasia because it has been part of Eurasia since the break up of Pangaea but for the last 30 million years or so it has been progressively detaching from Eurasia moving towards the east relative to Eurasia with a clockwise rotational component, the lack of widespread recognition of this plate boundary is dangerous since the boundary between Eurasia and the Amur plate is responsible for some of the highest mortality Earthquakes on Earth as the section represented by a transform boundary passes beneath a number of major metropolitan centers including the capital of China Beijing. There was even a deadly quake between the Amur plate and the Okhotsk plate back on January 1st 2024 in western Japan. We need to stop neglecting dangerous plate boundaries In each case GPS movements are enough to show the plates are moving independently and thus they are not intraplate Earthquakes just plate boundaries not represented on that map. There are many plate boundaries but most maps oversimplify these with a false inaccurate representation of plate tectonics. Plate boundaries are fuzzy and change with new ones forming over time albeit on longer timescales than people usually but these are things which still effect peoples lives which means you can't oversimplify things. On that note there is an interesting map where all the mostly tiny Earthquakes in the eastern US occurred between 1970 and 2015 and the intraplate Eathquakes through Eastern North America take on a striking pattern of two parallel lines one going from Oklahoma and Missouri up through the St. Lawrence seaway while the other cuts through from Arkansas up through New England and the Maritime provinces. Of these the New Madrid is the area with the largest historical quakes but it is not alone so we must be vigilant.
You shouldn't stand _under_ a tall brick building, you should lean right up against it. And earthquajkes don't last long ebnough for you to call 911 and reach someone before the bricks all fall on you 🙂 In fairness, I am torn between standing under doorway and under table. (writing this before having seen the answer). The "run out of the building" would depend on how close you are to door, and what environment exists around it (park with no buildings, vs right in middle of manhattan with 100 storey brick buildings all around).
The issue with running is that in strong quakes, you will have difficulty running and may be slammed into wall or fall down where material can fall on you. Better to stay put and get under something.
I'm late teach but I've got a note from Epstein's mother 😂🔨 EDIT::; I was attending Boise State University in August of 1983 or September I was the first one to notice the earthquake and I said earthquake and I went outside I was closest to the door and I was directly across from Broncos stadium I watched the 100 ft tall lights Bronco 🏟️ move in an ark I'm estimating at least a 15-ft swing in each direction within a few seconds overall swing of 30 ft movement , I remember looking at the other guys in my class and none of us took our eyes off from that stadium. On October 28, 1983, a magnitude 6.9 earthquake struck the Lost River Range in central Idaho, USA. The epicenter was located near Borah Peak, approximately 44.08°N latitude and 113.8°W longitude. This earthquake is considered the largest and most significant to affect Idaho. Impact Two schoolchildren, 7-year-old Tara Leaton and 6-year-old Travis Franck, were killed instantly when a stone storefront collapsed on them as they walked to school in Challis. RIP
![Felix "Unfair" | [Stray Kids : SKZ-PLAYER]](http://i.ytimg.com/vi/Oswujxm2Ag0/mqdefault.jpg)
Please LIKE and SUBSCRIBE. I also appreciate your continual support of these geology education videos. To do so, click on the three small dots (right of Download button above) then click on "Thanks") or you can go here: www.paypal.com/donate/?hosted_button_id=EWUSLG3GBS5W8 Or: www.buymeacoffee.com/shawnwillsey
Fantastic video. I was thinking just the other day how I wish I had been able to study geology when I was younger. Then you post videos like this and I feel like I’ve been given the chance again, thanks so much!
Just study space weather.Because that's what creates the earthquakes in the first place
Really a great explanation of earthquake waves. In the late 60's I was in an Air Force organization monitoring for underground nuclear detonations. We used the seismic waves to identify and locate the sources of these detonations. Energy wise, even large detonations are very small compared to earthquakes. We primarily used the P and S waves to determine distance and magnitude. Distance was calculated based on propagation time between the P and S wave, and amplitude of the signals at that distance gave us an estimate of the magnitude. One thing that may help in understanding of the Raleigh surface wave (the second surface wave) is to describe it as a corkscrew pattern going through the earth's crust. In the 60's it was described as an elliptical retrograde motion. Because these waves move both horizontally and vertically in a circular motion, these waves result in cracks in an X pattern on the side of a vertical concrete walls, and are the more destructive of the surfaced waves.
This explains why, during the first earthquake I was ever in while I was in bed, it felt like the bed was moving in circles!
I love this series you are putting together. I am not a student but I do find these very interesting.
Getting under an IKEA desk, like most people have at home will probably not offer much protection, lol.
Thanks!
Thanks for this, Shawn. As a third-year geologist student, I experienced a mag 3.2 quake. We were in the top/ 4th floor geology lab when the building swayed alarmingly for a few seconds. In three years, none of us had been told that we were only a mile away from a fault line, running between the north coast of Wales and the island of Anglesey! That was 45 years ago but still memorable 🙂. I wish you and your family a happy, healthy and prosperous new year.
Watched the Mythbusters episode years ago where they built a house on a shake table and experimented with best place to take cover in an earthquake. And it was indeed under a sturdy table holding on.
I kind of taught myself what to do in an earthquake. 1983 Borah Peak earthquake. I ran outside. When I saw the power poles waving and the lines swinging I went…oh this isn’t the place to be! Went back in and stood in the doorway. Ok…now I know to get under a table or desk.
Thank you, Shawn, for another easy to follow video. I have always been fascinated by volcanoes and earthquakes since I was a child but you make it easy to understand and clarify what has been confusing for me in the past. I am looking forward to you making earthquake magnitude easy to comprehend as well.
Thank you Shawn.
Thank you for another great educational clip! We get intra plate earthquakes in Australia. Nothing like plate boundary quakes but they can still be a good shake when they come through. Last one we had in my area was 2015 and could hear the movement in the house.
Thanks for all the hard work on these videos!
I remember seeing a picture of a building in Mexico City that pancaked in a large quake, but you can see the desks holding up the floors, so there was a survivable space left.
Part of the Earthquake scenario in Emergency Management, CERT, Red Cross Disaster and First Aid/Wilderness First Aid et al training, is to (1) Get under a desk, table, or sturdy/heavy furniture, (2) Put your one hand and forearm over your head and neck, protecting you from bumping your head/neck with the furniture - let alone any falling objects, and (3) with the other hand hold onto the (movable) desk, table, or sturdy/heavy furniture keeping it in place, but also keeping you under furniture at all times.
Reminds me of what we were taught in grade school during air raid drills in the 1960’s, only both arms went over your head.
@@Sinderbad Been there, done that. The reason they changed to this method - is that the desk, table, or furniture would shake and walk away from the covered individual and then they would get hit by falling debris. So they went for the 1 hand on head/neck, and 1 hand holding the desk, table, or furniture in place, or the person would crawl with the moving furniture !
The doorway myth, to the best of my knowledge, originated in my home state of CA where older building codes allowed for wider spacing (often 36" or greater) between beams in supporting walls, and very little cross-bracing. since doors are often around 30" wide the spacing of supporting beams was tighter, thus doorways were actually marginally more structurally sound. Codes were updated after the 1971 Sylmar EQ, and now require beams to be no more than 16" apart.
Important to keep in mind that in non-residential buildings like schools and hospitals doors tend to be much heavier and can have much more inertia when swinging freely if left open.
Thanks for a great lesson, Shawn!
The only reason I thought the doorway was accurate is because of the headers that support the weight of the walls above. Now that I actually have some knowledge that might be the best reason to NOT stand there.
Growing up in Los Angeles in the 60s and 70s and 80s feet, the official instructions for work for people to stand in a doorway during an earthquake. I know this has changed since I left LA. My brother-in-law was in San Francisco when the big one hit in 87. At that time, everyone was still being told to stand in the doorway. He found all of the doorways were full of people already when he got there.
That is one problem with doorways for sure. Plus getting to the doorway without being hit by falling debris.
I live in the New Madrid seismic zone... yes, that purple part in southernmost Illinois. Interestingly there is a fault system called the St. Genevieve (MO) fault that extends down into southern Illinois; it actually can be seen in aerial maps by those with keen eyes for that. The fault itself bisects my hometown (Anna) and the town next to it, Jonesboro.
The one EQ noted inside the African continent could be associated with the Great Rift that runs from Africa to Israel/Jordan, up into Turkey and Russia. This is the expanding earth rift of Ethiopia, that extends far south into this region.
The 1886 Charleston earthquake was a 7.0. Visitors today to the downtown peninsula can view “earthquake bolts” that literately “bolt” a house together in case of shaking from the Middleton fault. Come visit!
As I am watching this, was just hit by a 5.1 earthquake in Wellington, NZ. Will still be watching episodes to come 😂 Awesome work as always Shawn!
Great increases my knowledge of wave types… knew a little but that made sense … thank you Shawn
I experienced the 1989 Loma Prieta earthquake while living in the Bay Area. Its magnitude was eventually determined to be a 6.9. Of the many stories that stick with me about that event was from an interview with a student-athlete from Stanford University, whose campus was much closer to the epicenter in the Santa Cruz mountains. He said that the EQ began during Soccer practice (at 5:04 pm PDT).
The players were 20-something-year-olds in peak shape, playing on a huge flat pitch -- arguably the safest place you could hope to find yourself during a big earthquake, with nothing but open space and nothing to fall on you -- but, in the panic they were all trying to run away to, well, anywhere. But they couldn't, because the horizontal shaking (S-waves + Love waves) made it impossible for them to stand and keep their feet underneath them.
That's the story I try to get across to students about what they should do when an EQ begins. If it turns out to be a big, nearby event you have to assume that moving to a different location might just be impossible due to violent ground motion, so getting down low under a table or desk may be the only possible alternative.
Thank you for this very informative video. 😊 Very much appreciated!
This was great! I've lived in the SF Bay Area for about 20 years, so lots experience with smaller quakes, but it was great to understand them better. We actually heard a P-wave jiggle some paper once in Santa Rosa, about 5 seconds before we felt the shaking. We thought we had a mouse! Nope, just a P-wave.
In 1949 my mother and I were in Seattle waiting to board a passenger ship to go to Japan where my father was stationed. An earthquake struck and my mother and I stood in the doorway of the hotel we were in. My mother was born in Texas and as far as I know had never experienced a quake. I still remember watching the Murphy bed slam between open and closed.
If you visit Charleston SC you will definitely hear about that quake on the tours.
On your seismogram that you presented I thought I was looking at an electrocardiogram readout that noted ventricular tachycardia. 😎 nurse here.
I’ve felt at least 2 jolts in South Australia & Victoria, but they were really minor 2.0+. It was a little bizarre & what was that type of feeling! I remember 18 Dec last year & putting all devices on & frustrated with the fissure eruption as initially I couldn’t quite figure out the direction 😉
So, all these years, I thought I was feeling the P waves, but it's been the S waves. We have a lot in Humboldt, and I've grown accustomed to judging our earthquakes by that first felt jolt. Now I'll be looking for two before the real shaking starts 😂
Thank for the postings!
I grew-up in SoCal and automatically stand in the doorway if there's nothing to get under. Moved to Michigan and was in a cabin hit by a tornado. When the floor started shaking I went to the doorway... this is a really bad idea in a tornado.
When your phone tones and a USGS earthquake notification is received, activate the video camera on your phone and prepare to simulcast the event on social media….😜
For those of us who grew up in the early 1950s and remember “drop drills,” E was the immediate choice. Our teacher, with no warning, would yell “Drop!” and that we did, under our desks, curled up in a ball, facing away from windows, hands clasped behind our necks. For those who wonder why we did that, it wasn’t about earthquakes, it was about the fact that by then, the Soviet Union had nuclear weapons. And we had plenty of earthquakes in California’s San Fernando Valley, so sometimes we had that to contend with. Oh, and of course some guy always got one hand to his mouth to make fart noises and set everyone giggling.😂
Which wave causes a table lamp to almost tip over, then set it upright again? Shaking happened after. (Portland, OR. 1980)
My first earthquake was in Mumbai India, as a baby. Yes the Himalayas were on the move back then!
B was once advised years back.
At work one time we had a First Responder to earthquakes, foreign and domestic, come give a talk. He said they don't find people alive under desks and tables. They find people alive who are in voids created by the falling debris. Such as a roof beam held up by a wall. Of course it depends on the size of the quake, A small one where only the ceiling tiles fall you'll be good.
Back in my geology days we called surface waves “L” waves. During the Loma Prieta earthquake i was in Sacramento in a two story office building that looked out upon a basketball court. The waves were distinct and identifiable. I told the people sitting with me that that was a large quake, far enough away for the P,S & L waves to be segregated by the varying speed of each wave type.
I've felt a few in my lifetime living north of I90 here in NY.
I just watched a program about the Iznik, Turkey straight line fault earthquake in 2023, pictured.
18:17 My country The Netherlands has an increased risk due to an active normal fault in the southeast. in 1992 there was a damaging magnitude 5.8 quake on that fault and in 1932 a magnitude 5.0
But besides that, we have the quakes due to natural gas extraction in the northeast.
I wonder if there is some explanation why, although those are usually below 2.5 magnitude, it absolutely freaks the inhabitants out.
Is it only the fact that the country has little history in earthquakes, so we are not accustomed and not prepared (buildings are not constructed to be earthquake proof), or is there some other aspect to these quakes that makes them different from those caused by faults?
The P- and S-waves are very fast. Another wave of thinking about the speed these seismic waves is:
* P-waves travel at about Mach 15
* S-waves travel at a little less than Mach 10
(ignoring the fact that Mach numbers don't make a lot of sense within solid rock!)
The fastest airplane ever built - the SR-71 Blackbird or the less well-known A-12 Avenger - had a top speed of around Mach 3.4. The S-waves are more than *twice* that and the P-waves are *3 times* that.
Even small earthquakes can cause injuries. In 2015 a 4.1 struck north of where I live late in the evening while I was in bed. My cat used me as a launch pad in her haste to take cover. I had bloody claw marks on both legs. 😁
Question: Could one state that P waves are the actual rock movement, while S and Surface waves more akin to echoes ? ( a bit like thunder where the actual lightning is just a sharp bang, but further out, you hear echoes of that bang that reflect against clouds, and ground surface? )
Great information, Shawn. I love it, " . . . Eastern US . . . . " while pointing at the New Madrid fault system bisected by the Mississippi River. Spoken like an Idahoan such as myself who refers to anything East of Denver as "the East." I mentally pass right over the mid-west all the time. No offense intended. My first felt quake was 1978 in West Germany (courtesy of an Uncle Sam all expense paid 3 year trip), Salt lake in 1984, and 2020 again in Salt Lake. Wouldn't mind if I never experienced another.
My wife can feel those rarely felt waves. We were visiting Mt. St. Helens a few months ago. She asked if I felt anything I said no. She said she thought she did. We get back to our hotel I do a quick research for the time we were there & sure enough 2 small earthquakes did occur. They showed in 2.blah range.
Question. If you please Shawn.
I am just watching a documentary on the 2011 Japan Magnitude 9 earthquake. It lasted for 10 minutes in some areas. How much earth movement actually occurred in metres etc to result in that magnitude 9?
Question: Not long ago, I heard that the Canadian Shield is not only very old, but very very old because we came from Rodinia (our part was then known as Laurentia) and Laurentia collected other bits to grow to North America during its travels to the northern hemisphere. is the north american plate considered a single plate today, or are there still geological "welds" where the different bits from its creation have fused? Would such "welds" present opportunities for earthquakes?
Yes, suture zones where crustal blocks have joined or even places where there were rifts will consist of faults. These older faults are weak zones that can be reactivated by tectonic stress and produce quakes.
@@shawnwillsey Thanks. Are geologists able to see those suture zones between formely separate plates in North America? Or are they assumed to exist?
Preemptive situational awareness for if your in an earthquake moment on your 1st question cause every situation is different.
I have a question about option E. earthquake response. Getting under a sturdy table, etc. What keeps the building from collapsing and falling in on you smashing you under the table, burying you under a pile of debris, possibly killing you? None of the options looked good to me.
But it is the least bad option.
Depends on where you are, but actual physical collapse of buildings during an EQ is quite rare, especially in areas with up-to-date building codes that are enforced. The biggest danger indoors is always from falling objects -- a sturdy table will give you good protection from that.
@ Ok, thanks. Living in Kansas, I’m a novice when it comes to earthquakes, although we’ve had a few very weak ones.
In parts of Texas its fracking (lower magnitude earthquakes).
Geology Hub recently, dec 2024, had an episode on the seismically active regions in America. I have watched it several times.
Is that over simplified map of fault areas? graph not gram is what I learned.
I am surprised that Hawaii is 3rd in the standing. Would have expected 2018 eruption with the frequent tremors from the collapse of Halemaʻumaʻu every 12 hours to have brought up to at least 2nd position. Or were those tremors less than the 3.5 for your statistics?
The the Laurentian mountains north of Montréal, there is Mont Trembant (known as highest mountain in the range but not sure if that is factual).
It is at 46.22017745416989, -74.55292048013153.
Tremblant = Trembling and it was named because of the first nations called it a devils's mountain because of the deep ground shaking noises they kept hearing. And there are relatively often some mild tremors there. (in a summer cottage, noticeble because structure shakes a lot !). Am curious on the origin of the earthquakes in the oldest mountain ranges in the planet, far awar from any continental plate boundary. Or are the earthquakes there average for north america, but the composition of ground makes it felt more by locals? (read that the area is gneiss).
17:43 Aotearoa New Zealand is almost completely red.
We spend so much time in bed and yet I never hear how they want people to react when the big one hits at 3:17am
with respect, option A is the best choice. hiding under a table may safe you from some falling objects, how nice, but this is not what you should be afraid of during an earthquake. smth falling on you hurts but doesnt kill you. earthquake are extremely "peaky" that is to say most dont really kill anyone untill one kills ALOT of people. this happens when buildings collapse, and a table will absolutely not save you. this is clearly born out of the numbers, just because schools teach smth else is irrelevant.
if your worried about an auwie, hide
if your worried about your life? run
Um I'm pretty sure that the quake in east Africa is a plate boundary between the African and Somalian plates it's a young plate boundary but the area is a divergent plate boundary. You also have a quake along another young boundary namely the reactivated ninety east lineament fracture zone in the Indian ocean the extinct mid ocean ridge of the Indian ocean where the Indian plate has recently separated from the Australian plate as a strike slip transform plate boundary composed of both left lateral and right lateral lineaments due to the differences in plate motion between India and Australia as the Australian plate is currently moving north at about twice the rate of the Indian plate.
The quake in Mongolia is also notably near the Baikal rift zone where the Amur plate is in the process of detaching from Eurasia. The Amur plate is often lumped in with Eurasia because it has been part of Eurasia since the break up of Pangaea but for the last 30 million years or so it has been progressively detaching from Eurasia moving towards the east relative to Eurasia with a clockwise rotational component, the lack of widespread recognition of this plate boundary is dangerous since the boundary between Eurasia and the Amur plate is responsible for some of the highest mortality Earthquakes on Earth as the section represented by a transform boundary passes beneath a number of major metropolitan centers including the capital of China Beijing. There was even a deadly quake between the Amur plate and the Okhotsk plate back on January 1st 2024 in western Japan. We need to stop neglecting dangerous plate boundaries
In each case GPS movements are enough to show the plates are moving independently and thus they are not intraplate Earthquakes just plate boundaries not represented on that map. There are many plate boundaries but most maps oversimplify these with a false inaccurate representation of plate tectonics. Plate boundaries are fuzzy and change with new ones forming over time albeit on longer timescales than people usually but these are things which still effect peoples lives which means you can't oversimplify things.
On that note there is an interesting map where all the mostly tiny Earthquakes in the eastern US occurred between 1970 and 2015 and the intraplate Eathquakes through Eastern North America take on a striking pattern of two parallel lines one going from Oklahoma and Missouri up through the St. Lawrence seaway while the other cuts through from Arkansas up through New England and the Maritime provinces. Of these the New Madrid is the area with the largest historical quakes but it is not alone so we must be vigilant.
most arent violent. the ground rumbles.
I have never experienced an earthquake.
I do not believe earthquakes exist.
You shouldn't stand _under_ a tall brick building, you should lean right up against it. And earthquajkes don't last long ebnough for you to call 911 and reach someone before the bricks all fall on you 🙂 In fairness, I am torn between standing under doorway and under table. (writing this before having seen the answer). The "run out of the building" would depend on how close you are to door, and what environment exists around it (park with no buildings, vs right in middle of manhattan with 100 storey brick buildings all around).
The issue with running is that in strong quakes, you will have difficulty running and may be slammed into wall or fall down where material can fall on you. Better to stay put and get under something.
E
C
I'm late teach but I've got a note from Epstein's mother 😂🔨
EDIT::;
I was attending Boise State University in August of 1983 or September I was the first one to notice the earthquake and I said earthquake and I went outside I was closest to the door and I was directly across from Broncos stadium I watched the 100 ft tall lights Bronco 🏟️ move in an ark I'm estimating at least a 15-ft swing in each direction within a few seconds overall swing of 30 ft movement , I remember looking at the other guys in my class and none of us took our eyes off from that stadium.
On October 28, 1983, a magnitude 6.9 earthquake struck the Lost River Range in central Idaho, USA. The epicenter was located near Borah Peak, approximately 44.08°N latitude and 113.8°W longitude. This earthquake is considered the largest and most significant to affect Idaho.
Impact
Two schoolchildren, 7-year-old Tara Leaton and 6-year-old Travis Franck, were killed instantly when a stone storefront collapsed on them as they walked to school in Challis. RIP
earth quakes last seconds to maybe 2 minutes ,from what i experienced. me 92646. volcanic activity (earthquakes) makes gold come up.
👍👍👍👍👍👍
Thanks!
Thanks for your support.
E