Natural Hazards

1. a numerical scale for expressing the magnitude of an earthquake on the basis of seismograph oscillations. The more destructive earthquakes typically have magnitudes between about 5.5 and 8.9; the scale is logarithmic and a difference of one represents an approximate thirtyfold difference in magnitude.
4. a powerful tropical cyclone with sustained winds exceeding 74 mph.
5. an opening in the Earth's crust through which lava, ash, and gases erupt.
7. a path along the Pacific Ocean characterized by active volcanoes and frequent earthquakes.
10. a flow of soil or fine-grained sediment mixed with water down a steep unstable slope.
12. a period of time when an area or region experiences below-normal precipitation.
13. when loosely packed, water-logged sediments at or near the ground surface lose their strength in response to strong ground shaking.
16. a dense, fast-moving flow of solidified lava pieces, volcanic ash, and hot gases.
17. provides an estimate of earthquake size that is valid over the complete range of magnitudes

2. violently rotating columns of air, extending from a thunderstorm, which are in contact with the ground.
3. when something is collapsing on itself.
6. streams of molten rock that pour or ooze from an erupting vent.
8. the process of detecting and monitoring the physical characteristics of an area by measuring its reflected and emitted radiation at a distance
9. ocean waves triggered by: Large earthquakes that occur near or under the ocean.
11. An overflow of water onto normally dry land.
14. a sudden and violent shaking of the ground, sometimes causing great destruction, as a result of movements within the earth's crust or volcanic action.
15. a mass movement of material, such as rock, earth or debris, down a slope.