# Tag Info

52

It's Chimborazo, Ecuador, but only just, beating Huascarán, Peru, by less than 50 metres. Both are over 2 km 'higher' than Everest. I made a plot of some mountains — height above centre of the earth vs absolute latitude. You can download the IPython Notebook source code here. Warning: v. hacky. I can't find anything on the position of the centre of the ...

52

Water is a rather strange substance. With most substances, the solid phase is denser than is the liquid phase. This is not the case with water. Ice is less dense than liquid water. A side effect of this effect is that liquid water very close the the freezing point is less dense than is slightly warmer water. That very cool water sinks. Liquid fresh water ...

50

Water melts at 0 °C (32 °F) but freezing is a more complicated affair. It is safe to say water gains the ability to freeze at 0 °C, but it can get much cooler before it actually does so resulting in supercooled water. Water in this state can rapidly solidify when suitable ice nuclei are introduced. For example, in convective clouds, liquid water can be ...

42

If we consider only the magnetic field generated by natural sources, and not the ones generated by human activities. The general trend is that higher intensities of the magnetic field happen close to the magnetic poles. However, this is just a general trend. The southern hemisphere experiences the highest magnetic fields intensities, reaching over 65,000 nT, ...

35

According to Newton's Law of Gravity based on attractive force (gravitational force) that two masses exert on each other: $$F=\frac{GmM}{r^2}$$ Where: $F$ is the gravitational force $G = 6.67 \times 10^{-11}\ \mathrm{m}^3\ \mathrm{kg}^{-1}\ \mathrm{s}^{-2}$ is a constant of proportionality $M$ and $m$ are the two masses exerting the forces $r$ is the ...

35

Adding a little bit of practical data to the above answer about the Gutenberg-Richter relationship, here is a plot of the per-year cumulative probability of earthquakes in a particular province in Japan, based on observed frequencies over many hundreds of years: Source: http://topo.earth.chiba-u.jp/afr/backnumber/no24/24%E5%8F%B702kumamoto.pdf The ...

34

Note: I updated this answer to include a description of the historical techniques. Historical Techniques Newton developed his theory of gravitation primarily to explain the motions of the bodies that form the solar system. He also realized that while gravity makes the Earth orbit the Sun and the Moon orbit the Earth, it is also responsible for apples ...

33

We know the the size of the inner core through seismology. From my answer to this question: How are subsurface wave speeds determined without subsurface sensors?, we can determine the speeds of the different layers of earth. Pictured below is a diagram of raypaths going through the earth from the 1994 Northridge Earthquake in Southern California: (image ...

32

Earth's inner core is solid even though the temperature is so high because the pressure is also very high. According to the Wikipedia article on the Earth's inner core, the temperature at the center is $5,700\ \text{K}$ and the pressure is estimated to be $330$ to $360\ \text{GPa}$ ($\sim3\cdot10^{6}\ \text{atm}$). The phase diagram shown below (taken ...

32

Magnitude 10 earthquakes are indeed possible, but very very unlikely. You see the frequency of an Earthquake is given by the Gutenberg-Richter law: $$N = 10^{a-bM}$$ where $N$ is the number of earthquakes $\ge M (magnitude)$ and $a,b$ are constants. As you can see, the greater $M$ is, the less $N$ is. $a,b$ are generally solved for statistically, through ...

32

Are magnitude 10 earthquakes possible? The idea of a “Mega-Quake” – an earthquake of magnitude 10 or larger – while theoretically possible—is very highly unlikely. Earthquake magnitude is based in part on the length of faults -- the longer the fault, the larger the earthquake. The simple truth is that there are no known faults capable of ...

31

Part 1, see Neos answer. Earth will lose its heat no matter what we do, and our extraction of geothermal energy is insignificant (Wikipedia quotes a BP figure of 11.4 GW electrical, 28 GW heating). To answer part 2 of your question: if the Earth's core loses its heat, this will not have a major direct impact on climate. Internal heat generation is ...

28

The main resistance that winds have to their movements comes from the topography and surface obstacles. Therefore, as a general rule the closer to the surface the less wind you will find. But I guess you are interested in the winds in areas clear of surface obstacles, otherwise the answer would a be a cave or a dense forest somewhere. To figure out what is ...

25

Ground motion results due to passage of elastic waves. Now there are different kinds of waves, e.g., P waves, S waves, surface waves, etc. Most of the shaking (and therefore damage) is caused by surface waves. So if you are in a deep cave or mine then the amount of shaking you might experience can be much lower than on the surface. This of course assumes ...

23

I'll try to put time scales on each of these events. The Sun as a red giant - 5 to 6 billion years$^1$ The Sun is currently on the main sequence, which means that it's a "full grown" star - think of it as being middle-aged. It's been on the main sequence for around 4 to 5 billion years, and in 5 to 6 billion years, it will leave the main sequence. Most ...

22

Ocean lithosphere (geophysical definition of crust + upper mantle that acts as a 'plate') is primarily of basaltic composition - the upper levels are basalt and the lower levels are gabbro. The top levels have been proven with boreholes, whilst the lower levels have been inferred from transform fault sampling and comparisons with ophiolites. This sequence is ...

21

Well, firstly it's important to recognise that the poles are merely the extremities of the shape of a magnetic field - the earth's magnetic field. All magnetic fields have polarities as such. However, you're asking why the field itself even exists, I gather. In this case it's generated by electric currents in the conductive molten iron (and other metals) ...

21

In addition to the answers below and my comment above, I believe the following phase diagram, from DavePhd's answer here, sourced from here, is more appropriate for the pressure levels near the Earth's core of about 330 to 360GPa. We can see from the image that for pressures between 330 and 360GPa, the melting temperature ranges from about 6200 K to 6600 K, ...

21

Mount Chimborazo, which is 6,268 meters above sea level and within 1.5 degrees of the equator. More specifically, according to Dr. Milbert, Chief Geodesist, NOAA, National Geodetic Survey and Dr. Shum, Geodetic Science & Surveying, Ohio State Univ.: distance from Earth's center of mass, with an uncertainty of only +/- 2 meters: Mt. Chimborazo - 6384....

21

Due to convection (the cold water sinks while the warm water rises), the entire pond needs to be brought to near-freezing temperatures before the surface can freeze. With only the top of the pond in contact with the cold air, this takes a long time. ​‌‍​‌‍Additionally, the ground (which is not cooled by convection) will take even longer to cool down, ...

21

There is an entire field of Geophysics called gravimetry dedicated to measuring the magnitude of the gravitational field. First, we should distinguish between weight (a force) and gravity (an acceleration). Gravity is the acceleration that Earth gives to objects near its surface due to the gravitational force. The acceleration of an object near the ...

20

It's not too too likely, but it can happen. A few earthquakes have either been attributed to fracking, or the wastewater produced from fracking. According to the USGS (for more information, visit that page): Many questions have been raised about whether hydraulic fracturing — commonly known as “fracking”— is responsible for the recent increase of ...

20

There are two important ways to recognize different types of waves in seismic records: Their velocity. These waves travel at different speeds: P-waves are fastest, then S-waves, then Love waves, then Rayleigh. Since seismic recordings are measures of earth displacement, particle velocity, or water pressure over elapsed time, this means the waves show up at ...

20

Earthquake prediction really is a contentious issue, especially after the l'Aqula trials. However, let me try to elaborate how predictions might be possible in the future and what is inhibiting this development. We do have some understanding of earthquakes and rupture mechanisms. However, for prediction in a scale of hours (sufficient for evacuation), we ...

20

This hypothesis has been studied here as a possible explanation of selenogenesis (formation of the Moon). (Forming the Moon from terrestrial silicate-rich material. R.J. de Meijer, V.F. Anisichkin, W. van Westrenen. 2013.) The only place cited as suitable for spontaneous criticality is the Core-Mantle Boundary (CMB). The calculations above show that ...

20

Sea-level only sort-of corresponds to the oceanic–continental crust boundary. In depth, they don't correspond at all: It's the same story at an active margin: the plate boundary at a subduction zone is buried several kilometres beneath a wedge of sediment: What about spatially? As you can see from this map, they don't correspond all that well spatially ...

19

The Cascades (the volcanic range that Mt. St. Helens and Mt. Ranier are a part of) are "arc volcanoes" (a.k.a. "a volcanic arc", etc). Volcanic arcs form at a regular distance (and fairly regular spacing) behind subduction zones. Subduction zones are areas where dense oceanic crust dives beneath more buoyant crust (either younger oceanic crust or ...

19

The best argument I've heard supporting strong skepticism of plumes, if not total dismissal, is that the theory is too flexible. To put it more bluntly, this amounts to saying that it is unfalsifiable and therefore not helpful (in Popper's words, "A theory that explains everything, explains nothing."). Erik Lundin, a Norwegian geologist, is a fairly ...

19

This question is relevant, Why is the inside of the Earth so hot? The short answer is the core is losing heat no matter what we do. You see, heat is transported from the core to the surface, but its important to think of heat in terms of energy. Since there is a finite amount of energy within the earth, we are actually transferring energy from the inside to ...

19

The first thing you should think about is how the accretionary disk cooled and the cosmochemical constraints this put on Earth (But I am not going into details here). From studying meteorites it is apparent that the oldest meteorites don't show signs of chemical differentiation (e.g. melting, ...) and are thought to represent the solids that formed from the ...

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