1. California’s Natural Hazards

2. California’s geology has unique natural hazards that goes along with its natural beauty.

3. California is in danger of earthquakes, which could cause liquefaction, seismic shaking, landslides, and tsunamis.

4. There are volcanic hazards and the potential for mudflows and flooding due to storms.

5. Hundreds of earthquakes happen each day in California. Most of them are so small they can’t be felt, but those above a magnitude 5 can be dangerous.

6. Tsunamis, which are shifts in the ocean floor that send sea waves in all directions, can grow to enormous sizes as it nears the shore.

7. Earthquakes at subduction zones all around the Pacific Ocean can cause tsunamis. In Northern California where the Juan de Fuca plate is sinking under the North American Plate is a place that could generate tsunamis.

8. Scientists have evidence that in the past 200 years, more than a dozen locally generated tsunamis have struck California coastlines.

9. In 1964 a major earthquake in Alaska produced a tsunami that struck Crescent City hours later, killing 12 people. Crescent City, California

10. Seismic shaking or the amount of ground shaking that occurs during a quake can cause damage to structures. The more consolidated or solid the ground the better the structure can absorb the seismic waves.

11. The modified Mercali Scale describes the effects of seismic shaking. It measures how strong the earthquake was felt and how much damage it did, in other words its intensity.

12. Liquefaction is another natural hazard that is caused by seismic shaking. As the unconsolidated soil shakes the water in the pores of the soil shake out toward the bottom.

13. This leaves air pockets which causes the soil to sometimes sink under the weight of structures that are above it.

14. Earthquakes often cause loose rock and soil on slopes to move. This is called a landslide. Most landslides occur on steep slopes where sediment is loose or rock is fractured.

15. California has volcanic hazards as well. Natural hazards from volcanic eruptions include volcanic ash, pyroclastic flows, lava flows and volcanic gasses.

16. The Cascade Range which extends from Washington down to Northern California has several composite (Stratovolcanos) volcanoes.

17. In California we have Black Butte, Mt. Shasta, Lassen Peak, and Medicine Lake Volcano. Only Mt. Shasta and Lassen Peak are classified as active.

18. Volcanic fields, such as the Long Valley Caldera near Mammoth Lakes, has current active volcanism. In 1980 the town of Mammoth Lakes was evacuated because scientists believed an eruption was about to happen.

19. The last natural hazards California has to endure are mudflows and flooding due to storms. Mudflows happen most often when fires burn hillsides and the topsoil is exposed and when heavy rains fall the mudflows come down.

20. In Northern California flooding happens in the river delta areas in the Central Valley due to more water than the rivers can hold.