Please LIKE and SUBSCRIBE. I also appreciate your continual support of these geology education videos. To do so, click on the "Thanks" button just above (right of Download button) or by going here: www.paypal.com/donate/?hosted_button_id=EWUSLG3GBS5W8 Or: www.buymeacoffee.com/shawnwillsey
Shawn, at 26:24, that's a mistake on the diagram. That energy level was for the Soviet Union's ,Tsar Bomba' (King Bomb), which was a thermonuclear (Hydrogen) bomb, and equated to about 56 megatons of TNT. Hiroshima and Nagasaki nuclear fission bombs (one Uranium bomb and one Plutonium bomb) were very much smaller than that; the energy equivalent of around 16 and 25 kilotons of TNT.
In the early 90s i worked as an electronics intern for the geophysical institute at the university of Alaska in Fairbanks. I and another guy were sent out to install seismic and telemetry equipment in remote locations to include the mouth of st augustine volcano. Funny story is years after i left i went back to visit the guys where they took out a map and said they sent a crew to update a certain site i helped build between Fairbanks and Anchorage, but they couldnt find it. It was a site initially chosen by them that looked good but our helicopter couldnt land there. On the fly we picked a similar ledge about a mile away, installed the tower, radios, antenna, batteries, burried the sensor, then tested... we reported the new location upon return. I took one look at their map and immediately noticed their problem... they were looking in the wrong place... they failed to document our new site. Boy, were they ever red in the face. That expensive gear would have been lost for eternity if i hadnt paused my trip to visit the GI and say hello. Apparently the guy with whom i did the field work had left the department a year after i did and he would have been the only other reference. I loved that work.
You are doing such an awesome explanation of how thees things happen that I as a 66 year old remember being taught the magnitude scale when I was in grade school. Please continue teaching us!
Thank you, again, Shawn, for making a complex subject easy to understand. I knew my way around the Modified Mercalli Scale but had found the change from the Richter Scale to the Moment Magnitude Scale hard to fathom, but you made the difference easy to grasp. I hope you have a great New Year.
Good morning,sir! Will you explain in physical geology only, or in other branches like geophysics? thanks for your videos they are so benificial for me.
The ~32x energy difference makes quick-and-dirty comparisons of energy differences fairly easy: 2 tenths of a point in magnitude is equivalent to a doubling in energy, So the rough energy difference between Mw 8.8 and Mw 7.0 is 500x (2^9). The difference in depth of 22 miles to 8 miles reduces the total energy difference by a factor of ~7.5 (using the inverse square law). This brings the total surface energy relative to the two sites to a difference of 60x to 70x, before even considering other factors. One of the big secondary factors is that the epicenter of Haiti EQ was directly beneath Port-Au-Prince, where more than half of the population lived -- maximum shaking was concentrated in this area. In Chile the shaking lasted much longer but the energy was distributed over a much larger area.
One question that i've had since watching the Icelandic eruptions and the EQs associated with magmatic movement: How accurate are the calculated focus positions. Are we talking +/- 10m, 100m, 1000m? Or maybe a percentage of the distance from the various seismometers?
Thanks for video. I don't understand how did you calculate the epicenter distance by P and S wave difference time? And how did you the focus of earthquake within the earth?
In actual fact, in the final quiz, it is the "32" that is the rounded number. A Moment Magnitude difference of 2, as in the example, is a factor of exactly 1000 in the energy released. (The "32" is just a handy, easy to remember approximation. It should really be 10 times the square root of 10, or the square root of 1000: 31.6227766...)
Yet another final comment 😂: The Moment Magnitude scale uses a subscript of "W" to denote "work". To quote Wikipedia: Caltech seismologist Hiroo Kanamori [...] took the simple but important step of defining a magnitude based on estimates of radiated energy, Mw , where the "w" stood for work (energy)
About ten minutes in I’m wondering are you going to mention negative depth earthquakes? That’s probably not a 101 topic though. The first time I ran across one of those lead me down a long reading rabbit hole about how sea level affects the zero depth in the model.
Quick question: why is the graph of S/P wave times vs distance not a couple of straight lines? Is it because of the waves travelling through the Earth, not across a plane, and also possibly them encountering different material in the Earth's interior with different propagation speeds?
Earthquakes this one subject we should know about. One the main things that we have to worry about here in Idaho right on the canyon rim is earthquakes. Mount Borah is very much alive if there's any movement there we will feel it, if the Wasatches move we will feel it, if something happens in the Ruby Range or in the Silver Zones we will only feel small tremors. Here is a big difference between the different types of earthquakes that you will feel: p-waves come from the Earth's core you will feel them when they hit. S-waves also called aftershocks are closer to the surface. S-waves cannot go through volcanic rock and when you look at a seismograph you can barely see them. You know when an earthquake is coming when you see the big p-wave on the seismograph. If you are in an earthquake zone get on the ground and squat and cover your head. Look for anything solid a door, edge of a bed a desk anything. Stay away from windows and never go outside. All earthquakes must be reported to the USGS the moment they hit or to the Rock Doctor himself and Wilsey will report it to the USGS. Remember an earthquake can strike anytime anywhere and we will not notice it until it's too late. Be prepared for anything.
My sister lives in Santiago, Chile. in that 2010 EQ, They were sleeping on the 16th floor of their modern, anti seismic apartment. Little damage to the building but furniture , pictures dishes, all bouncing and breaking. It was horrific and loooooong !!.....they were OK otherwise. Rocks Rule !
What kind of energy is released in an earthquake? Is it the strain energy density integrated over some region of rock surrounding the focus that is released after the fault shifts?
30:33. "An 8.1 is worse than a 7.6". Ok, please tell me if got the math right 8.1 - 7.6 = 0.5 or 1/2. 32 to the 1/2 power is the same as the square root of 32 or 5.66 (rounded off). So a 8.1 earthquake releases 5.66 times as much energy as a 7.6 earthquake.
Another question (you'd hate me if I were a real student). In the Vanuatu earthquake footage of "CCTV video: People flee cafe as magnitude 7.3 earthquake hits Vanuatu" from Associated Press, which I assume you have seen, we can see people running out (and 2 falling), but then, something very violent happens with the fridges suddently moving a large distance (probably about 1m). If I had had a very precise GPS attached to one of the building's columns, would it have recorded the whole building moving while the fridges stayed put and would the building's position have returned to normal at the end, of would there have been a permanent shift in position of similar magnitute as we saw the fridges move? Or did the fridges get "thrown" by the ground with some vertical movement which amplified their horizontal travel and the ground didn't move horizontally that much? Since the building retained power, is it safe to state whatever this building experienced was experienced equally over a much larger area otherwise power cables would have snapped somewhere? Would this video properly represent the different phases P, S and Surface waves)? People fleeing as part of P wave and fridges vuiolelntly moving as part of S or later Surface waves?
A GPS units attached to objects that can move or be thrown around by the earthquake wouldn't record information that would be very useful to anyone, because there are too many factors involved, like how the building the object is in was constructed as well as how tall it is (if the height of the building matches the 'period' / timing of the earthquake waves, and they last a while, then the building will experience 'resonance' - like giving a swing a little push at just the right point can make it swing higher and higher - and can fail catastrophically whereas buildings much taller or shorter will do better). Also tons more factors like the size, shape, weight of the fridge, which way it was facing compared to the direction of the waves, how top-heavy it was, etc. Too much of a mishmash of irrelevant data. Seismometers are attached to solid ground. They just measure the shaking of the ground not the shaking of a particular building or refrigerator.
@@ingridcc1-123 But attaching GPS to the building's columns that are anchored into ground would show if the building moved 1m and the fridges didn't move, or whether the building barely moved by vibration caused fridges to move.
Over 100 years ago Edgar Cayce prophesied California will fall into the ocean. (Actually the quote is that California will become an archipelago.) On a road trip through the San Joaquin Valley it dawned on me what he meant. (Hint: Sacramento is 10 m above current sea level.) No earthquakes required.
100 years ago, plate tectonics was unknown. Edgar Cayce didn't understand basic geology and the fact that California, west of the San Andreas fault, is attached to and sitting on top of the Pacific plate.
Technically they are spheres. It's just that above the ground there is no transfer of energy. They are spheres because the shockwaves travel in all directions as the same speed. This creates a sphere. Where the spheres intersect, you draw a line directly vertical to the surface to determine the epicenter.
@ The spheres interact at the surface. But it seems to me the circumference of the circles at a given distance from the seismometer on the surface of the earth indicates the latitude and longitude at which one should “dig down” or “drop a plumb line”. But what do I know, I’m just a regular human, albeit one with STEM training,
Hemispheres match the parameters of the distance. An EQ 1000 km away from you could mean 1000 km to the north, to the south-east, etc. It could also (in theory) be 1000 km below you. Points on the surface of a cylinder would be progressively further from the seismograph as you go deeper. For an EQ at depth, the circles won't intersect at the surface, they'll overlap leaving a gap in the shape of a pseudo-triangle. But the spheres will all intersect at a single point beneath the surface, giving you the depth
If you beleive in the conspiracy theory that the Earth is a obloid sphere instead of established fact it is flat, the half sphere vs cylinder model works better when distances are great. The Earth's (alleged) curvature means that the intersection between 2 spheres sufficiently apart may happen below ground level. And the distance calculated at a seismograph is accurately reflected by the sphere model since the radius = distance and remains accurante everywhere along surface of sphere below ground. In a cylinder, the distance between surface of cylinder and the seismograph increases as you go deeper so you exceed the calculated distance.
How dare you force us to study between Christmas and News Years 🙂 Your presentation treated the focus as a "point" (with one very very brief mention it ot could be longer). Wouldn't a movement typically involve one side of a fault moving against the other side over a certain distance? Wouldn't the lenght of fault involved in the movement be a major part of the energy released? Surrely, 2 10cm diameter rocks moving agaist each other can't cause a calamity with high rises topplng over, bridges falling into San Francisco bay, or Los Angeles losing its bouyancy and sinking into the Pacific to create new beach front properties in San Bernadino? Are they able to calculate the length of a fault involved in an earthquake? If you have 2 alternate universes where in one, you gave a 8.0 magnitude earthquake with movement over 1km of San andreas fault, while in the other universe it is an 8.0 over the same area, but 5km of San Adreas fault moves (and both at same depth). Would both generate the same damage intensity but the second one have wider area of damage? or would it release far more energy due to 5 times the mass of rocks moving?
Please LIKE and SUBSCRIBE. I also appreciate your continual support of these geology education videos. To do so, click on the "Thanks" button just above (right of Download button) or by going here: www.paypal.com/donate/?hosted_button_id=EWUSLG3GBS5W8 Or: www.buymeacoffee.com/shawnwillsey
Shawn, at 26:24, that's a mistake on the diagram. That energy level was for the Soviet Union's ,Tsar Bomba' (King Bomb), which was a thermonuclear (Hydrogen) bomb, and equated to about 56 megatons of TNT. Hiroshima and Nagasaki nuclear fission bombs (one Uranium bomb and one Plutonium bomb) were very much smaller than that; the energy equivalent of around 16 and 25 kilotons of TNT.
In the early 90s i worked as an electronics intern for the geophysical institute at the university of Alaska in Fairbanks. I and another guy were sent out to install seismic and telemetry equipment in remote locations to include the mouth of st augustine volcano. Funny story is years after i left i went back to visit the guys where they took out a map and said they sent a crew to update a certain site i helped build between Fairbanks and Anchorage, but they couldnt find it. It was a site initially chosen by them that looked good but our helicopter couldnt land there. On the fly we picked a similar ledge about a mile away, installed the tower, radios, antenna, batteries, burried the sensor, then tested... we reported the new location upon return. I took one look at their map and immediately noticed their problem... they were looking in the wrong place... they failed to document our new site. Boy, were they ever red in the face. That expensive gear would have been lost for eternity if i hadnt paused my trip to visit the GI and say hello. Apparently the guy with whom i did the field work had left the department a year after i did and he would have been the only other reference. I loved that work.
Pleaseeeee keep these coming, I am in introductory geoscience right now and your videos make it so much easier to absorb the information.
Final note: thanks for the simple and clear explanation of the problems with the Richter scale and the need for the Moment Magnitude scale. 👍🏻
You are welcome.
¡Gracias! Greetings from Mexico. Happy New Year Profesor Shawn
Thanks!
Thank you Shawn.
You are doing such an awesome explanation of how thees things happen that I as a 66 year old remember being taught the magnitude scale when I was in grade school. Please continue teaching us!
Thank you, again, Shawn, for making a complex subject easy to understand. I knew my way around the Modified Mercalli Scale but had found the change from the Richter Scale to the Moment Magnitude Scale hard to fathom, but you made the difference easy to grasp. I hope you have a great New Year.
Ahh mind blown those numbers are massive.. thanks for a little seasonal grounding. Cheers Shawn
ありがとうございます！
Much appreciated
Earthquake study and coffee. The best mix. A real earthquake would spill my coffee, #!@p*! Thanks, Shawn!
Thank you for the classroom time, you are an amazing teacher and person. Giving back the way you do inspires me to do the same, give back.
Very good, very interesting. Thanks, really enjoyable learning series.
Fascinating. Thank you so much Shawn! Happy New Year to you and your family! ❤
You continue to date my overall knowledge Doc, lol. The Intensity Scale was not around when I was in school. Good stuff, thanks.
Thanks for another fascinating lesson, Shawn. I didn't know about the second scale for measuring earthquakes. Happy New Year!
Great job!!👏
Good morning,sir!
Will you explain in physical geology only, or in other branches like geophysics?
thanks for your videos they are so benificial for me.
Thanks
I knew that a magnitude 6 was much bigger than a 4, but I didn't realize HOW much. The scale is crazy!
Cuz magnitudes use exponential functions. 😳
excellent
The ~32x energy difference makes quick-and-dirty comparisons of energy differences fairly easy: 2 tenths of a point in magnitude is equivalent to a doubling in energy, So the rough energy difference between Mw 8.8 and Mw 7.0 is 500x (2^9). The difference in depth of 22 miles to 8 miles reduces the total energy difference by a factor of ~7.5 (using the inverse square law). This brings the total surface energy relative to the two sites to a difference of 60x to 70x, before even considering other factors. One of the big secondary factors is that the epicenter of Haiti EQ was directly beneath Port-Au-Prince, where more than half of the population lived -- maximum shaking was concentrated in this area. In Chile the shaking lasted much longer but the energy was distributed over a much larger area.
One question that i've had since watching the Icelandic eruptions and the EQs associated with magmatic movement: How accurate are the calculated focus positions. Are we talking +/- 10m, 100m, 1000m? Or maybe a percentage of the distance from the various seismometers?
Thanks for video. I don't understand how did you calculate the epicenter distance by P and S wave difference time? And how did you the focus of earthquake within the earth?
In actual fact, in the final quiz, it is the "32" that is the rounded number. A Moment Magnitude difference of 2, as in the example, is a factor of exactly 1000 in the energy released. (The "32" is just a handy, easy to remember approximation. It should really be 10 times the square root of 10, or the square root of 1000: 31.6227766...)
Yet another final comment 😂:
The Moment Magnitude scale uses a subscript of "W" to denote "work". To quote Wikipedia:
Caltech seismologist Hiroo Kanamori [...] took the simple but important step of defining a magnitude based on estimates of radiated energy, Mw , where the "w" stood for work (energy)
About ten minutes in I’m wondering are you going to mention negative depth earthquakes? That’s probably not a 101 topic though. The first time I ran across one of those lead me down a long reading rabbit hole about how sea level affects the zero depth in the model.
Quick question: why is the graph of S/P wave times vs distance not a couple of straight lines? Is it because of the waves travelling through the Earth, not across a plane, and also possibly them encountering different material in the Earth's interior with different propagation speeds?
Earthquakes this one subject we should know about. One the main things that we have to worry about here in Idaho right on the canyon rim is earthquakes. Mount Borah is very much alive if there's any movement there we will feel it, if the Wasatches move we will feel it, if something happens in the Ruby Range or in the Silver Zones we will only feel small tremors. Here is a big difference between the different types of earthquakes that you will feel: p-waves come from the Earth's core you will feel them when they hit. S-waves also called aftershocks are closer to the surface. S-waves cannot go through volcanic rock and when you look at a seismograph you can barely see them. You know when an earthquake is coming when you see the big p-wave on the seismograph. If you are in an earthquake zone get on the ground and squat and cover your head. Look for anything solid a door, edge of a bed a desk anything. Stay away from windows and never go outside. All earthquakes must be reported to the USGS the moment they hit or to the Rock Doctor himself and Wilsey will report it to the USGS. Remember an earthquake can strike anytime anywhere and we will not notice it until it's too late. Be prepared for anything.
How do they work out the total amount of energy released
My sister lives in Santiago, Chile. in that 2010 EQ, They were sleeping on the 16th floor of their modern, anti seismic apartment. Little damage to the building but furniture , pictures dishes, all bouncing and breaking. It was horrific and loooooong !!.....they were OK otherwise. Rocks Rule !
What kind of energy is released in an earthquake? Is it the strain energy density integrated over some region of rock surrounding the focus that is released after the fault shifts?
30:33. "An 8.1 is worse than a 7.6". Ok, please tell me if got the math right 8.1 - 7.6 = 0.5 or 1/2. 32 to the 1/2 power is the same as the square root of 32 or 5.66 (rounded off). So a 8.1 earthquake releases 5.66 times as much energy as a 7.6 earthquake.
Congratulations! You nailed it.
Well do I remember the Nisqually earthquake, being 4 miles from the epicenter. I saw lamp posts waving side to side, and my car doing the same.
Science rules....end of story...mic drop...keep it coming!
Kia Ora from New Zealand
Eq1 = christchurch earthquakes (but many)
Eq2 = kaikoura earthquake (from 180km away felt like a wave form)
Good Content, you need to link up with thegeomodel guy Phillip Prince.
Another question (you'd hate me if I were a real student). In the Vanuatu earthquake footage of "CCTV video: People flee cafe as magnitude 7.3 earthquake hits Vanuatu" from Associated Press, which I assume you have seen, we can see people running out (and 2 falling), but then, something very violent happens with the fridges suddently moving a large distance (probably about 1m).
If I had had a very precise GPS attached to one of the building's columns, would it have recorded the whole building moving while the fridges stayed put and would the building's position have returned to normal at the end, of would there have been a permanent shift in position of similar magnitute as we saw the fridges move?
Or did the fridges get "thrown" by the ground with some vertical movement which amplified their horizontal travel and the ground didn't move horizontally that much?
Since the building retained power, is it safe to state whatever this building experienced was experienced equally over a much larger area otherwise power cables would have snapped somewhere?
Would this video properly represent the different phases P, S and Surface waves)? People fleeing as part of P wave and fridges vuiolelntly moving as part of S or later Surface waves?
A GPS units attached to objects that can move or be thrown around by the earthquake wouldn't record information that would be very useful to anyone, because there are too many factors involved, like how the building the object is in was constructed as well as how tall it is (if the height of the building matches the 'period' / timing of the earthquake waves, and they last a while, then the building will experience 'resonance' - like giving a swing a little push at just the right point can make it swing higher and higher - and can fail catastrophically whereas buildings much taller or shorter will do better). Also tons more factors like the size, shape, weight of the fridge, which way it was facing compared to the direction of the waves, how top-heavy it was, etc. Too much of a mishmash of irrelevant data. Seismometers are attached to solid ground. They just measure the shaking of the ground not the shaking of a particular building or refrigerator.
@@ingridcc1-123 But attaching GPS to the building's columns that are anchored into ground would show if the building moved 1m and the fridges didn't move, or whether the building barely moved by vibration caused fridges to move.
Over 100 years ago Edgar Cayce prophesied California will fall into the ocean. (Actually the quote is that California will become an archipelago.) On a road trip through the San Joaquin Valley it dawned on me what he meant. (Hint: Sacramento is 10 m above current sea level.) No earthquakes required.
100 years ago, plate tectonics was unknown. Edgar Cayce didn't understand basic geology and the fact that California, west of the San Andreas fault, is attached to and sitting on top of the Pacific plate.
@@oscarmedina1303 I don't think Edgar was thinking much about sea level rise either.
Nomogram calculation!
Why can earth sciences conceive of a centric view while our solar system is constantly portrayed as a membrane rather than centric?
Instead of bowls wouldn’t it be a cylinder? The epicenter would be where the cylinders touch each other at the depth of the epicenter?
I think you’re right! If they were bowls, there would be no point of intersection other than at the surface.
Technically they are spheres. It's just that above the ground there is no transfer of energy. They are spheres because the shockwaves travel in all directions as the same speed. This creates a sphere. Where the spheres intersect, you draw a line directly vertical to the surface to determine the epicenter.
@ The spheres interact at the surface. But it seems to me the circumference of the circles at a given distance from the seismometer on the surface of the earth indicates the latitude and longitude at which one should “dig down” or “drop a plumb line”. But what do I know, I’m just a regular human, albeit one with STEM training,
Hemispheres match the parameters of the distance. An EQ 1000 km away from you could mean 1000 km to the north, to the south-east, etc. It could also (in theory) be 1000 km below you. Points on the surface of a cylinder would be progressively further from the seismograph as you go deeper.
For an EQ at depth, the circles won't intersect at the surface, they'll overlap leaving a gap in the shape of a pseudo-triangle. But the spheres will all intersect at a single point beneath the surface, giving you the depth
If you beleive in the conspiracy theory that the Earth is a obloid sphere instead of established fact it is flat, the half sphere vs cylinder model works better when distances are great. The Earth's (alleged) curvature means that the intersection between 2 spheres sufficiently apart may happen below ground level. And the distance calculated at a seismograph is accurately reflected by the sphere model since the radius = distance and remains accurante everywhere along surface of sphere below ground. In a cylinder, the distance between surface of cylinder and the seismograph increases as you go deeper so you exceed the calculated distance.
Triangulation..
How dare you force us to study between Christmas and News Years 🙂
Your presentation treated the focus as a "point" (with one very very brief mention it ot could be longer). Wouldn't a movement typically involve one side of a fault moving against the other side over a certain distance? Wouldn't the lenght of fault involved in the movement be a major part of the energy released? Surrely, 2 10cm diameter rocks moving agaist each other can't cause a calamity with high rises topplng over, bridges falling into San Francisco bay, or Los Angeles losing its bouyancy and sinking into the Pacific to create new beach front properties in San Bernadino?
Are they able to calculate the length of a fault involved in an earthquake?
If you have 2 alternate universes where in one, you gave a 8.0 magnitude earthquake with movement over 1km of San andreas fault, while in the other universe it is an 8.0 over the same area, but 5km of San Adreas fault moves (and both at same depth). Would both generate the same damage intensity but the second one have wider area of damage? or would it release far more energy due to 5 times the mass of rocks moving?
Thanks!
Thanks!
Thanks!
Thanks!