"Are there 'earthquakes' on Mars? What's inside the Earth and Mars? What causes earthquakes and how are they measured? What is Plate Tectonics?"
From the Inside Out
Scientists do not have very much information about the inside of Mars because there is very little movement in its crust. They use seismographs (earthquake recorders) and other instruments to determine what the inside of Earth is like and have guessed that our neighbor planet has a solid iron core and a thick crust of cooled rock.
The core is small in diameter and the crust makes up most of the planet (left, NASA/JPL). There are various bulges on the planet including the Tharsis Region where there was past volcanic activity. Find out more about the Tharsis Region of Mars on the Volcanoes page.
Scientists have been studying Earth for long enough to determine that it has four basic layers (right). It has a solid inner core surrounded by a liquid metal outer core. A mantle of solid rock covers the core and then the Earth's crust.
The Earth's Inner Core is about 5000° hot and about 1400 km in diameter. The Outer Core is liquid iron and nickel about 2100 km thick and produces the Earth's magnetic field. Mars has a very tiny magnetic field indicating a solid core. Dense rocks up to 3200 km thick make up the Mantle. The Crust is about 70 km thick and is made of minerals and sedimentary, igneous and metamorphic rock. We live on just the top few hundred meters of our 12,756.28 km diameter planet.
Here are some basic terms used in the tour. Find more geology terms in the Glossary.
- Volcanic rock caused by partial melting of the Earth's crust.
- The spot on the surface of the Earth directly above the area where an earthquake took place.
- A split or fracture in the Earth's crust where two blocks of crust have slipped, slid or pushed against each other.
- Focus (Earthquake)
- The area inside the Earth where an earthquake happened. Also known as the Hypocenter.
- The area inside the Earth where an earthquake happened. Also known as the Focus.
- The observed effects that an earthquake shaking the ground has on people, buildings, man-made structures and natural features.
- The seismic (earthquake) energy recorded on a seismograph.
- Mercalli Intensity Scale, Modified
- Earthquake intensity measured on a scale that has 12 increasing levels. The scale takes into account how people "felt" the quake and the observed structural damage.
- Richter Magnitude Scale
- A scale that mathematically rates how much force an earthquake releases based on seismograph readings.
Kids' Cosmos… Expanding Minds Beyond the Limits of the Universe
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