California’s Natural Hazards Chapter 13A, Section 3

California’s Earthquake Hazards Natural Hazard – an event that results from Earth processes and that can cause damage and endanger human life Natural hazards that result from California’s earthquakes include tsunamis, seismic shaking, liquefaction, and landslides Scientists have evidence that in the past 200 years, more than a dozen locally generated tsunamis have struck the CA coastline Seismic Shaking – measure of how much ground movement occurs during a quake The amount of shaking depends on the rock and soil location of an area Modified Mercalli Scale – describes the effects of seismic shaking Earthquakes in CA can also cause liquefaction and landslides, collapsing and damaging homes

West Coast Tsunami Warning System

Earthquake Hazards

Earthquake Hazards

Concept Check Where are landslides due to seismic shaking most likely to occur? They are most likely to occur on steep slopes or in areas underlain by weak soils.

California’s Volcanic Hazards Natural Hazards from volcanic eruptions in California include volcanic ash, lava flows, and volcanic gases The Cascade Range stretches from Washington into northern CA Cascade volcanoes in CA include: Black Butte, Mount Shasta, Medicine Lake Volcano, and Lassen Peak The two volcanoes that are classified as active are Mount Shasta (late 1700s) and Lassen Peak (early 1900s) Volcanic Field – an area covered by volcanic rocks The Long Valley Caldera is the focus of a large volcanic field on the eastern side of the Sierra Nevada (some rocks are only a few hundred years old!) Carbon dioxide escaping from the ground beneath Mammoth Mountain is killing trees in the area

Lassen Peak Mount Shasta

Long Valley Caldera

Concept Check What is a volcanic field? A volcanic field is an area that is covered by volcanic rocks.

California’s Storm Hazards Two main storm-related hazards in California are mudflows and flooding The dry conditions in southern CA make it very susceptible to mudflows and flooding, especially when precipitation is greater than normal A mudflow is a mass of very wet soil, and sometimes rock, that flows quickly downhill At top speed, a mudflow can move nearly 60 km/hour, destroying everything in its path Flash floods occur in mountains and deserts; they can be deadly because the floodwaters rise rapidly and move quickly

Mudflows and Flooding

Assignment Read Chapter 13A, Section 3 (pg. CA 20-CA 26) Do Section 13A.3 Assessment #1-6 (pg. CA 26) Study for the Final!!!