Scientists study the Earth’s interior by studying seismic waves generated by earthquakes and explosions that travel through Earth and across its surface. These waves, which are waves of energy that travel through Earth, move similarly to the energy from the point of an earthquake. By tracking these waves, scientists have learned what makes up the planet’s interior.
The history of how Earth’s interior evolved and how it accounts for many aspects of our planet’s behavior remains largely unwritten. By studying seismic waves, scientists have discovered the internal structure of the planet. Accurate images of the inside of the earth are obtained through seismic tomography.
Seismic waves are used to understand Earth’s interior, as they move similarly to the energy from the point of an earthquake. The scientific understanding of the internal structure of Earth is based on observations of topography, bathymetry, rock in outcrop, and samples. Earth’s interior is broadly grouped into three main layers based on chemical composition: crust, mantle, and core.
Since no one has ever sampled the interior below the crust directly, scientists must deduce its composition either by looking at clues hidden in igneous and metamorphic rocks or by examining proxies for composition and structure. In the early 1900s, Croatian seismologist Andrija Mohorovičić made one of the first seismology-related discoveries about Earth’s interior.
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How did seismologists learn about Earth’s interior?
Earthquakes generate seismic waves that travel through the Earth, allowing seismologists to explore its deep interior. The 1994 earthquake near Northridge, California, illustrates this process and Earth’s interior structure. Seismologists use ground motion recordings to explore the Earth’s deep interior. Shear waves propagate outwards from an earthquake in all directions, and the outer core is assumed to be molten due to liquids not being sheared. However, shear waves are observed as they pass through the inner core, which transmits shear energy, indicating its solidity. To request hardcopies of E and O materials, email EandOproduct@iris. edu.
What is the evidence for the Earth’s interior?
Geologists employ a combination of direct and indirect evidence derived from rock samples and seismic waves to gain insight into the internal structure of the Earth.
How can the interior of the Earth be studied?
Seismology is the study of seismic waves, which are energy from earthquakes that travel through the Earth’s interior. Seismologists use these waves to understand earthquakes and the Earth’s interior. Two types of seismic waves are P-waves and S-waves, which travel through the solid body of the Earth. P-waves travel through solids, liquids, and gases, while S-waves only move through solids. Surface waves only travel along Earth’s surface. Body waves produce sharp jolts in an earthquake, but do not cause as much damage as surface waves.
Why do you think scientists study the Earth’s interior?
Seismograms provide information about the speed of body waves traveling through Earth’s internal layers, allowing us to determine the material they are traveling through. As body waves travel through the Earth’s internal layers, their speed changes, causing them to bend. This bending is similar to a straw in a half-full glass of water, where light waves bend and slow down as they hit different materials.
Body waves help us understand the Earth’s surface, which is solid, and the layer of rock below the crust, known as the mantle. Seismic waves bend and pick up speed where these two layers meet, indicating that the mantle has a different density than the crust.
How is the earth’s interior determined by measuring?
Seismic waves, created by earthquakes, allow seismologists to explore the Earth’s deep interior. Data from the 1994 earthquake near Northridge, California, illustrates this process and Earth’s interior structure. Seismic shadow zones reveal how P waves travel through solids and liquids, while S waves are stopped by the liquid outer core. The wave properties of light are used to understand seismic-wave behavior.
How did early scientists learn about what was inside of the Earth?
Andrija Mohorovicic, a geologist, discovered in 1909 that earthquake waves near the surface moved slower than those passing through the Earth’s interior. He also observed that the primary waves, which were the strongest, did not move straight and were bent or deflected by something. This led him to conclude that the Earth’s crust was made of less dense material, such as rock, and the mantle was much denser, explaining why earthquake waves moved slower through the crust.
Mohorovicic also learned about the outer and inner core, which were formed by the release of secondary waves, which are slower. German geologist Beno Gutenberg believed that the outer core must be made of a liquid, as the slower S waves could not pass through it and were deflected off course. The inner core, composed of hot metals like iron and nickel, has the highest pressures, forcing the metals to vibrate in place like a solid.
Earthquake waves that reach this layer move at the greatest speeds because waves move through solids faster than through gases and liquids. This discovery demonstrates the existence of different layers in Earth’s structure and behavior.
Why do you think scientists study the earth’s interior?
Seismograms provide information about the speed of body waves traveling through Earth’s internal layers, allowing us to determine the material they are traveling through. As body waves travel through the Earth’s internal layers, their speed changes, causing them to bend. This bending is similar to a straw in a half-full glass of water, where light waves bend and slow down as they hit different materials.
Body waves help us understand the Earth’s surface, which is solid, and the layer of rock below the crust, known as the mantle. Seismic waves bend and pick up speed where these two layers meet, indicating that the mantle has a different density than the crust.
How did scientists know that the Earth is layered?
The available evidence indicates that the Earth’s materials have formed distinct layers with varying densities. These layers are primarily sourced from seismic waves and vibrations generated by earthquakes or explosions.
How do we determine the structure of the Earth’s interior?
The internal structure and composition of the Earth are determined through a variety of sources, including observations of surface rock, geophysical data obtained from seismic activity, heat flow, magnetic field measurements, gravity observations, laboratory experiments conducted on surface rocks and minerals, and comparisons with other planetary bodies.
What do scientists use to explore the interior of the Earth?
Scientists study the interior of the Earth by observing how seismic waves from earthquakes are bent, reflected, accelerated, or delayed by various layers of the Earth’s crust, mantle, and core. This method of investigation differs from the conventional approach of drilling holes for samples in the crust.
How have scientists determined the structure of Earth’s interior?
Seismic waves, which are analogous to sound, light, and water waves, are a category of energy-transporting waves that scientists utilize to gain insight into the internal structure of the Earth.
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As for drilling, the USSR drilled the 12km deep Kola superdeep borehole near the border with Norway in the 1970s, but stopped when the drill heads kept failing because of the high temperature of the rock at that depth; they reported that is behaved more like plastic, and as a machinist, I can attest to the difficulty of cutting plastic (it’s softer than metal, but the swarf likes to get jammed up in the flutes of the cutter). Still quite impressive, especially for the time.
As a geologist, a few thoughts: 1. Missing a drilling target by 300m is bad drilling 2. 1.4km is a pretty shallow well 3. As my old igenous petrology professor, and, as Hank tells us, there’s an awful lot of information you can get from extrusive igneous rocks (basalts etc.) 4. Geologists love drilling anomalies (or, bulls eye’s as they look on EM etc. maps)!
So I’m commenting before perusal the article… I took a planetary geology course at UHCL with Dr. Mike Zelensky about 20 years ago. He worked at NASA. He said at that time they thought there was probably a crystal cube in the center core of Earth. It likely was encased in a sphere made of slightly different liquid metal, that it would spin or float around in. Different layers/spheres followed that. They used seismic data to determine this best theory. Update: I’ve not talked to him since. I’ve not heard any more about it either. So I’m guessing that this has been debunked. Thanks for a super cool article!
I don’t understand why we don’t utilize geothermal energy more. The two obstacles, up front costs and location are very easy to get beyond by the involvement of the countries with the largest economies. As far as up front costs, well, geothermal historically comes in at a whopping savings of 80%! It quickly returns the start up costs. Then, the location. Well, why can’t Iceland and any other country where geothermal opportunities abound, why can’t they lease the land to the larger countries upon which industries that use a lot of energy can be built? Iceland has a small population, and should welcome people from around the world. If all heavy industry which used huge amounts of electricity were to switch to geothermal, one, global warming would be greatly reduced, and two, significant savings to consumers is realized, helping the poorest of countries. Icelands unemployment rate would dip into a negative number. It’s trade and commerce would boom. This is unlike the preposterous things going on where Saudi Arabia was leased water rights in ARIZONA, virtually a desert, to grow alfalfa, and ship it, dry bundles of grass, back to livestock farms in Saudi Arabia. What government agent took that bribe? Taking down a water table in a desert to grow hay. The water table has lowered substantially and take hundreds, if not thousands of years to replenish. I don’t think it will ever come back,as the earths climate has permanently changed. Hardly any jobs created, and consider the carbon footprint in the transportation of a low density commodity overland, to the ports, put on tankers to cross the ocean, and travel overland to its destination.
After the Ridgecrest earthquake I 3d printed the shake map from usgs data and noticed that there were a few spots near the epicenter that had relatively little movement. Seeing this I theorized that either there was little to no data for those areas (it is a NAVY base after all) or the crust in that area is made up of something that reflects or absorbs the shockwaves.
The mantle is not molten !!! Common mistake .. It’s just has very high temperatures but it is considered to be solid, because these seismic waves called S waves can pass through it. These waves are stopped by liquids however. You make great articles but I thought it’s very important to make this distinction
(1:32) At 7.6 miles, the Kola Superdeep Borehole is the deepest bore hole since 1989. There have been longer bore holes, but none as deep. IODP drilling through a thin spot on the ocean floor is something of a shortcut by comparison, but even that came up short at just over 1 mile deep (not counting ocean depth).
I’m sorry sci show. Your description of the different geophysical techniques aside from seismic and gravity is very confused. You were mixing up electromagnetic and magnetic anomalies. The changing earth magnetic field used of deep earth imaging is due to the long term variations but short term changes caused by lightning strikes and space weather.
Thought… Build an unmanned drill like probe, about the size of an SUV with a nuclear battery like the rovers sent to Mars? Give it equipment to be able to scan as it drills so it doesn’t just fruitlessly drill against something too hard to get through or so it doesn’t tunnel into a cavern or lava-tube?
Great website! perusal it a lot. Now I expect there’s a whole bunch of editors behind this website by now and I wonder what makes your intonation as it is. Is that a conscious choice? I can follow you and you come across lively and enthusiastically, but I keep getting so distracted by the fact that every single sentence has pretty much exactly the same melodic outline… long sentences just stretch the same pattern short ones get: an “up and catching” start – an explanatory middle “floaty” bit, with importance-underlining pauses – a “rounding off drop” at the end. I’d love know if there’s a specific reason you do that and also if there are others who get distracted by that.
My friend, you really need to try to take a breath or two in between items on your list! If you can’t see the screen (whether visually impaired or listening while crafting/working/eating/etc) there is no way to tell when you’re moving on to another item. It’s like trying to read a book with no paragraphs!
“Molten mantle?” Seriously SciShow? You should know better than that. The mantle is almost entirely solid; if it was otherwise, s-waves (shear/secondary waves) released from earthquakes would not travel through the mantle…they don’t travel through the outer core for this exact reason. Also, diamonds may be spectacular, but they aren’t the “most informative” type of xenolith. You can learn a lot from all kinds of xenoliths, diamonds among them, but it would be impossible to say diamonds provided MORE information than the other types.
ThE EARTH/ground AND what is THE SUN are CLEARLY (and necessarily) E=MC2 AND F=ma IN BALANCE, AS ELECTROMAGNETISM/energy is gravity. TIME is NECESSARILY possible/potential AND actual IN BALANCE, AS E=MC2 IS F=ma; AS ELECTROMAGNETISM/energy is gravity. Gravity IS ELECTROMAGNETISM/energy. By Frank DiMeglio
Something is amis with what was said and what what graphic was shown on screen which has confused me: You talked about the ratio of radioactive lutitium and it’s daughter hafnium. On screen you showed a picture of Lu-174, and Hf-178. Lu-174 doesn’t decay into hafnium; it’s actually the other way around. Also, Hf-178 is stable, but is created by Lu-178. I’m just interested to know what the specific isotopes are supposed to be in this segment; obviously what is shown on screen is a minor error (pun intended)
Coming from a Geology Major at Oxford University. The mantle isn’t molten! Most of the Mantle geotherm doesn’t cross the solidus line (a like which represents that at a specific temperature/pressure, the mantle STARTS melting). Plate tectonics occur due to Partial melting of the upper mantle (the asthenosphere) in certain cases ie subduction zones, mantle plumes etc but that cause a max 10-40% melt. So the majority of the mantle is SOLID I love Scishow been perusal for years! Just trying to clear up this common misconception that even I had before starting my university degree
Where can we discuss this or ask about it? I would doubt my comment would be answered. I was wondering if we should drill toward the center of the gravitational weakspots, instead of trying to dig at the deepest sections of the earth? I saw a huge place off the coast of florida. I also wonder why we haven’t created some kind of probe that can dig and maybe change the physical matter of the dirt to reduce its size or something and be nuclear powered so it could dig until it got somewhere. Do we have anything that could survive swimming through lava? If we could we could send it through a volcano couldn’t we?
I’m just not convinced it’s possible to know scientifically if there are layers below the mantle. Most of the studies and evidence that is presented here are still based on levels no deeper than the crust. Aquifers, mines, etc…are all still part of the crust. In order to be proved, it has to be OBSERVABLE. Models are not actual observation, and are based on our own best GUESS using reasoning, but not true scientific method.
Another exciting thing and possibility, what if dinosaurs were preserved in one of the compartment areas of the hollow Earth preserved and sent there to thrive like Noahs arc of the deep. Another question, why do Abaddon wants to conquer Satans kingdom strategically located in the Earths core with his other members on the surface of Earth planting his seeds and propagating. It is because of the enormous amount of energy in the Earths core and its very strong gravitational pull according to his mindset if conquered would enable him to project his influence and power not only on the Earth surface but also in the universe by the aid of our moon projection.
Too bad most of the scientific research can only be done while looking for oil or mineral deposits, so as a scientist you are very constraint when it comes about research. We need an global research program where every contry throws some money so smart people cand do thier jobs freely and not following some big corporation agenda.
Great article Hank. An observation, however. Is there ANY specific reason why as soon as you finish one sentence you have edited the clips so that the next sentence starts without any sort of pause? Makes the content rather hard to listen to after a while with the constant ‘bang, bang, bang’ sort of effect imho.
The Earth molten mantle have variable temperature and pressure as it goes closer to the core – this creates fluctuation and variable current of the molten mantle like the regional current systems of water in the oceans. Since the molten mantle current is moving iron – it creates a magnetic field that generates magnetic field that protects the Earth Atmosphere via the Van Allen Radiation Belt. Mapping the regional molten mantle circulation patterns is the stuff one get your Doctorate /Thesis approved as long as you can figure out how to do these readings and how to get the money to do it. it is the lack of a hot enough molten mantle in the planet Mars that prevents Mars from having a viable atmosphere – essentially making Mars a dead planet.
I once heard that the peridotite in the mantle was under too much pressure to be molten, but rather like the consistency of a snow cone is to liquid. Its when the pressure subsides that it is allowed to ‘flow’ usually creating pools from which volcano’s will form. It makes more sense than a liquid mantle if you think about it. A liquid rock mantle would be very unstable and the continents would float about a lot quicker. Passing the orbit of Jupiter would cause the core to rock around as well if it were a fluid. Not easy to find info that goes in depth though, just the usual ‘pop’ stuff.
Actually xenoliths are country rock from earths crust that get trap in molten lava. Also called inclusions. Learned that from my college geology class. They do not come from the mantle, they are pre-exsisting rocks that are caught in by lava, mostly in lava tubes from mafic volancoes such as shield volcanoes and basalt plateaus, or can be found in laccoliths or batholiths. But yea, that’s what they are.
Can anyone point me a to a source that could help me understand the following… how basically chunks of dust and rock floating in space coming together turn into a large ball of molten rock that then cools to form the crust. Im wondering how it came to be a big molten ball. In my head asteriods and other space debris came together to form a round body and grew due to gravity attracting more and more material, but in my head i see a solid ball forming, where it would be internal pressures causing things to turn molten. Obviously im missing some part(s) of the narrative. Thanks in advance for any pointers.
Our neighbor is reacting indirectly asking papaano Yan? in Tagalog language, pertaining to the images the inhabitants in the hollow Earth sees the same images seen on the Earth’s surface, as if asking about the evil spirits contained within the heat in the Earth’s core like seeing what the non confined areas spirits seen on the surface. Remember there’s an inner and 2nd inner Earth cores and above that are the areas of hollow Earth and the abyss, meaning there’s partition within the cores first and second layers of core sealed off and there’s compartments in the orange fruit like containments of layers vertically like the layers of orange fruit shielding them from intruders and shielding them from extreme heat of the core at the same time balancing the temperatures within the many layers because of stones absorbing waters and the gas effects of some heat in the core that managed to pass through meaning not all heat are shielded otherwise they will freeze in cold because there are sinkholes gathering sea water within as well as the water exchange on the surface mountains which diffuses as gases and water molecules in the inside underground.That’s the thing his mind did not reach at the moment.
Also i would recommend you guys look at Bowen’s reaction series in respect to the crystallization of minerals in earths magma/lava. Diamonds are not xenoliths in any respect, but are minerals that are found in earth crust because of the decomposed humus finding it’s way to the underlayers of the crust that undergo a metamorphic change that makes it a high grade metamorphic rock that could survive earths magma and THEN could end up as xenoliths. They don’t start out as xenoliths. It’s good to clarify these things to avoid miscommunication and false facts to others who do not know as much. Also never use a .com as a source. Proper academic research would use a .edu more oft than not or rather a .org or .gov. you could also just read the research paper itself and just link it too.
What is this bs. No man dug deeper hole than 20 km. What is this science from gossip girl? Someone said that someone said. And no you cannot see billions light years away because your telescope cannot reach this far because of the field of view of your lens and that everything converges in one point. 😅What a joke. Everyone who understands basic lens and eye behaviour knows that there is vanishing point of your eye and lens. Simple example. You are standing on the streets with lamp posts. The farther away they are the more they converge in the middle and they meet in one point. This is called perspective. So your eye has limited fov and limited resolution. When you use lens it is same concept. You cannot see more than the best lens on earth. And do not tell me we have satelites. Satelite lens is limited as well. Biggest telescopes on earth are like a car. And you tell me that lens in satelite has better resolution than lens on earth which is 10000mm and a size of the car? Joke
Regarding the timing of the formation of Earth’s crust, how do we know the planet was ever completely molten? If it started as solid rocks coalescing, then heating from the center due to gravitational contraction and radioactivity, how do we know that the surface ever melted completely (or nearly so)? Isn’t it possible that there were always some large patches of solid material though not necessarily the same material as time advanced?
Infact the crust lava discovery is also common sense, if it didn’t happen we would never have geothermal activity because then the entire earth would be solid. Partial melting or full melting of earths crust or the composition of the magma itself actually help determine the type of volcano it is if any at all. It determines if it is a felsic or mafic or intermediate volcanoe. The more you know