Questions tagged [geodesy]

Geodesy is the science of accurately measuring and understanding three fundamental properties of the Earth: its geometric shape, its orientation in space, and its gravity field as well as the changes of these properties with time.

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82
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6answers
25k views

What place on Earth is closest to the Sun?

What is the location on Earth that is closest to the Sun? I've seen this question asked many times, and answered in varied and contradictory ways: The most common answer is “the summit of Chimborazo ...
19
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2answers
373 views

To what accuracy and precision do we know the volume of the Earth?

Satellites such as GOCE and GRACE measure the geoid with unprecedented accuracy. Altimeters can determine local surface elevation with millimetre-precision. This makes me wonder: to what precision ...
13
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3answers
9k views

Why is earth not a sphere?

We've all learned at school that the earth was a sphere. Actually, it is more nearly a slightly flattened sphere - an oblate ellipsoid of revolution, also called an oblate spheroid. This is an ellipse ...
12
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1answer
228 views

Do normal modes of oscillation cause permanent deformation?

It is known that when a large earthquake occurs, say $M \ge 9.0$, The surface waves travel around Earth over and over, "ringing the surface like a bell". The GIF below is an example (Image Source): ...
9
votes
2answers
640 views

Terrain correction for gravity data using Nagy, 1973

I am working with an algorithm for terrain correction of gravity data. I am using Nagy, 1973. However, I could not get the results I need. So, this is the problem. I have this function where x,y,z ...
6
votes
1answer
189 views

Why do we measure eustatic sea-level from the center of earth?

Earth is rotating so it has a ellipsoidal shape. The measurement will therefore be different from equator and pole. So why do we measure eustatic sea-level from the center of earth?
4
votes
1answer
66 views

Plate boundary lon/lat data

I'm working on a map in GMT and am having trouble finding lon/lat data for the minor plate boundaries (specifically the adriatic). Is there a database I can refer to?
3
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1answer
99 views

Great circle in UTM coordinates

I've got a question about calculation of great circles in Cartesian coordinates: Is it possible to compute points along a great circle in UTM coordinates, i.e. given two points P1(easting1, northing1)...
3
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0answers
67 views

What gravitational evidence do we have to counter the idea that oceans are formed when continents sink?

Is there some evidence for this based on gravity anomalies? I think I know how to tell if a mountain or structure is compensated based on bougeur and free air anomalies, but this really has me ...
2
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1answer
62 views

If the accuracy of measurement of the earth's volume is not known, how can scientists assert that the earth is not expanding?

Volcanic eruptions, undersea earthquakes, fissures in the crust, meteoroid accumulation could all be seen as empirical evidence of expansion of the earth. Sink holes and other phenomena could be ...
0
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1answer
54 views

Possible cavern?

In eastern Ontario, Canada, there's a place where, when walking and stomping, you can hear a hollowness in the ground. The area is primarily igneous rock with many large boulders, and the spot in ...
0
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1answer
97 views

I need help with these geode like rocks [closed]

I found these rocks in my pasture and was excited because I thought I had found some geodes. The rocks were in a sandy bank and looked like eggs sticking out of the bank. I am located in Ness County ...