Geology 310T Exam 1 Latest Update Graded A

Geology 310T Exam 1 Latest Update Graded A natural hazard process that is a potential threat to human life and property (could have not taken place yet) natural disaster natural event that causes significant damage to life or property (already happened) catastrophe natural event that kills or injures large numbers of people or causes major property damage Types of Hazards Earthquakes, landslides, volcanoes, tsunamis, thunderstorms, tornadoes, hurricanes, pollution/climate change, coastal erosion/ waves, floods, wildfires Hazards can lead to other hazards Earthquakes to tsunamis, hurricanes to floods Common hazards in Southern California earthquakes, wildfires, windstorms, coastal erosion/waves Why have we seen increase in cost/fatalities as a result of natural disasters over the past several decades? Because of increase in population and structures. Human casualties have decreased because of technology. Actual number of natural disasters has stayed about the same. Why do people live in hazardous areas? They don't always know it. Could be cultural, economic or frivolous reasons. Plus past disasters are easily forgotten. What is the most common hazard? Heat & drought What is the least common hazard? Volcanoes Is it possible to predict a catastrophe? Yes, but not always. We can avoid them by getting out of the way. It may be possible to forecast hazardous events by looking at past events. How often is there an a big earthquake at the San Andrea's Fault? Every 180-200 years What can we do to mitigate hazards? Asses risks, prepare for disasters to reduce damage, land use restrictions, get insurance, educate ourselves. lithospheric plates A dozen or so segments of the lithosphere that cover Earth's outer part. Above the asthenosphere. crust Earth's outermost layer, very light, contains silicone & oxygen= silicate. Two types: continental crust and oceanic crust mantle Thick layer of Earth below the thin crust and above core, heavier than crust. Contains iron, magnesium, silicone, oxygen. core The central part of the earth below the mantle. consists of nickel and iron. Outer core is liquid, inner core is solid. divergent boundary a spreading plate boundary such as mid-oceanic ridge. Plates pull apart or rift (by sinking of heavy lithospere at trenches) commonly creating rift valleys that eventually with ocean crust and ocean water as the continents split apart. Small shallow earth quakes at rift valley convergent boundary A tectonic plate boundary along which 2 plates come together by subduction or continent-continent collision. Both types have earthquakes and mountains transform boundary The boundary between tectonic plates that are sliding past each other horizontally. No subduction so no volcanoes. Have lots of earthquakes. Bends at these boundaries cause mountains and basins. subduction The process by which lithosperic plate (usually oceanic) descends beneath another plate at a convergent plate boundary. hotspot A weak spot in the middle of a tectonic plate where magma surfaces; forms a volcano (ex: Hawaii & Yellowstone) continental drift the idea that continents were once together but have split apart. Pangea a super continent that existed 820 million years ago and split apart 200 years ago. Dinosaurs existed in Pangea. Alfred Wegner credited for continental drift theory. seafloor spreading the process by which new oceanic crust forms along a mid-ocean ridge and older oceanic crust moves away from the ridge. force within the Earth that causes the mantle to move Ring of Fire the chain of volcanoes that lines the Pacific Rim trench extremely deep areas in the ocean that are created by a subducting plate rift valley A deep valley that forms where two plates move apart Evidence for Wegner's continental drift hypothesis matching shapes of the continental margins, matching rock types, deformation styles, fossils, and glacial patterns. What is the general concept behind continental drift and how does sea floor spreading fit into that concept? Continental drift is the idea that the continents were once together but have been split apart. Sea floor spreading is how they have come to split. Harry Hess recognized that convection was happening when he saw underwater ridges. Pillow basalts making up these ridges indicatethat these rocks formed underwater.The age of the seafloor itself is youngest near the ridges and oldest away from them.Older rocks convect and get recycled. Theory of Plate Tectonics Wegner's continental drift hypothesis and Harry Hess' seafloor spreading concept plus new research gave us the Theory of Plate Techtonics which states: earth's crust is broken into plates that move and interact (collide, separate, slide over each other) caused by convection. characteristics of Divergent plate boundary underwater ridges, (Mid-Atlantic Ridge), shallow earthquake, creation of new seafloor and a widening ocean basin. characteristics of Convergent plate boundary earthquakes, volcanoes, the formation of mountains (Andes Mountains), tsunamis characteristics of Transform plate boundary big earthquakes, valleys and river beds (San Andreas Fault)