Natural Geologic Hazards A visual tour of worldwide natural geologic hazards

Earthquakes Earthquakes can be powerful movers of the Earth’s crust Annual cost of damages in the US alone is $3.9billion hill.com/sites/ /student _view0/chapter16/animations_and _movies.html#

Some Earthquake damage Loma Prieta, 1989 Paso Robles, 2004 Northridge, nter/recenteqsus/

Earthquake theory Stresses build up due to plate motion Rocks distort and store more energy Rocks rupture, an earthquake occurs Final offset along the fault centeqsus/

Volcanic Eruptions There are approximately 3000 active volcanoes About 50 volcanoes erupt every year 80,000 people have been killed by volcanoes since 1900 Mt. St. Helens caused about $1billion in damage

Hawaiian volcanic flow Mt. Lassen vents Hawaiian Visitor’s Center

Volcano Cross section Partial melting of rock occurs at subduction and divergent plate boundaries and at hot spots* Magma flows upward through weaknesses in the lithosphere

Tsunami Tsunami hit California coastlines in 1946, 1952, 1957, 1960 and 1964 Over 80 tsunami have been reported in the last 100 years Damage estimate for the 1964 tsunami was over $10million.

Crescent City Tsunami, April, 1964 Banda Ache devastation, Dec 24, 2004

Tsunami formation Ocean floor before the earthquake Earthquake occurs. Faulting pushes Earth upwards Tsunami is generated. Waves move outward. Tsunami wave height grows towards shore NAGTWorkshops/visua lization/collections/tsun ami.html

Landslides Aka mudslides. avalanches, hillside creep, lahars Can be fast or slow, dry or watery Average US annual losses are $2billion and 25 ~ 50 deaths

Evolution of Landslides Landslides occur due to gravity pulling weak material downhill Steeper slopes = greater downward pulling-effect Weakened rock enhances potential of sliding (rain, water, earthquakes, volcanic blasts, ice, weight etc…) 07/animations/ch15_animations/animation1.html

Coastal Erosion 85% of California’s shoreline is actively eroding El Nino winter poses the greatest threat to coastlines due to increased storms Ca damages of $116million for the winter of ’82~’83

Coastal erosion

Processes of Coastal Erosion ACross section of beach cliff BWave begins undercutting the base of a cliff CCliff falls due to removal of supporting base DNewly exposed cliff is subject to ongoing erosional attack