Fault Lines and Earthquakes
Here are a few last views of basalt, scoured fields and loess in road cuts. We have only a few more miles to go to return to Spokane.
[349.0 MM 257 Interstate 90 East]
Near Cheney are the Lance Hills, rolling hills that have been shaped by the floods.
|"Elongated hills oriented northeast-southwest, parallel to the flood flows, are additional evidence of the catastrophic flooding this region endured. Compare Lance Hills...with satellite imagery of the Chryse Planitia region on Mars to see the stunning similarities in landforms." [Buchanan]|
[368.0 MM 276 Interstate 90 East]
Just outside of Spokane are basalt outcroppings and a long loess-filled area in the roadcuts. In the photo at right, the fill is about 40 feet long.
You may have noticed that in the scablands there are very few trees but, as we return to Spokane, we see evergreen forests.
In 2001, Spokane felt a number of earthquakes related to a fault line, running north to south, just east of the city. Although no devestating damage occured many residents were frightened and concerned. Some heard low rumblings and were awakened at night while others heard and felt nothing. These quakes were near the surface, possibly in the basalt layers.
Earthquakes are caused by forces deep within the Earth's crust. As continents collide, ocean floors split, magma flows, volcanoes erupt and other natural processes occur pressure is released making vibrations within the ground which we call earthquakes. Click here to find out more about earthquakes.
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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