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MT 6: CALIFORNIA GEOLOGY LT 1: Natural Hazards Why are we studying CA Geology? • We live in California and it is a state standard. • California has major, unique geological features and history. • California is located on the west coast of the United States. The United States is part of the North American continent. • The North American plate meets the Pacific plate directly under the crust of our state. • California is in a zone of major plate movement and activity. • California was formed as a result of this tectonic plate movement for thousands of years. • Also California has been carved from wind, water, ice, and erosion on the surface of the Earth to form our unique landscape. So what is the unique landscape of California? • Very tall and large mountain range called the Sierra Nevada Range. • Large Eastern deserts. • Located directly in contact with the largest ocean in the world called the Pacific Ocean. • Northern California is cooler and receives more precipitation. • Southern California is warmer and receives less precipitation. CA Natural Hazards • The most dangerous events and natural hazards that result from them for different areas of Ca are • Storms • Earthquakes • Volcanoes CA: Natural Hazards • What is the importance? • Natural hazards can cause damage and endanger human life CA Natural Hazards • Storms (excess of Precipitation) -Winter storms typically bring rain to lower elevations and snow to the mountains. -Two main storm-related hazards in California are mudflows and flooding. • A mudflow often starts in a depression on a steep hillside. • At first, a mudflow moves fairly slowly-about 16 kilometers per hour. • But as the mud engulfs more and more loose debris, it picks up speed. • At top speed, a mudflow can move nearly 60 kilometers per hour, destroying everything in its path. • Flooding Is another California storm hazard. • Some of the state’s floods are regional floods. • Some flooding in California occurs when excessive rainfall causes dams and levees to fail. CA Natural Hazards • Earthquakes -When Californian’s thinks of Natural Hazards, Earthquakes are the first to come in mind. -Hundreds of earthquakes occur each day in California. -But the stronger Earthquakes, especially quakes with a magnitude of 5 or higher can be dangerous. – • Is a wave formed when the ocean floor shifts suddenly during an earthquake. • As a Tsunami nears land and begins to break, the Tsunami can grow to enormous size. • A Tsunami gains speed as it gets closer to land • A Tsunami acts like a wall of water – • Is a measure of how much ground movement occurs during an earthquake. • Seismic Shaking reflects the behavior of an earthquake’s seismic waves. • Can cause buildings, freeways and structures to collapse – • Occurs when water-soaked soil turns to a thick, soupy liquid during an earthquake • As liquefaction takes place, buildings and other structures quickly collapse into soft mud. – • Occur on steep slopes where sediment is loose or where rocks are highly fractured. • Earthquakes can also cause landslides in areas that are underlain by weak soils. CA Natural Hazards • Volcanoes • Many are surprised to learn that parts of the state are at risk from volcano‘s. – • the dust that comes off the burning rock of the volcano. • Can be harmful to plant, animal and human respiratory system • Can block incoming solar radiation that is needed to survive – • Lava flow is produced when lava breaks through the surface of a volcano and starts to travel down the sides. • Lava flows can destroy whole villages and help create new land masses. • Magmatic gases and high-temperature volcanic gases, • Low-temperature volcanic gases and hydrothermal systems, • Non-explosive volcanic gas release WHICH HAZARD DO YOU THINK EFFECTS YOU THE MOST?