EARTH 20 Lecture Notes - Lecture 1: Falsifiability, Metamorphic Rock, Return Period
Processes and Natural Hazards
➔ Processes: physical, chemical, and biological ways in which events affect Earth’s
surface
◆ Internal processes come from forces within Earth
● Plate tectonics (earthquakes, volcanic eruptions)
● Result of internal energy of Earth
◆ External processes come from forces on Earth’s surface
● Atmospheric effects (weather, hurricanes, tornadoes)
● Result from external energy from the Sun
Hazard, Disaster or Catastrophe
➔ Hazard: natural process or event that is a potential threat to human life
◆ Potential for an earthquake or volcanic eruption
◆ Examples: earthquakes, volcanoes, tsunami, climate change, fires, floods,
impacts, mass extinctions
➔ Disaster: hazardous event that occurs over a limited time in a defined area
◆ Criteria
● 10+ people killed
● 100+ people affected
● State of emergency is declared
● International assistance is requested
Disaster Trends
➔ Dramatic increase in natural disasters
◆ Not an increase in earthquakes, but an increase in the human toll
◆ Caused by atmospheric air temperature rises
➔ UN 1990’s “Decade for Natural Hazards Reduction”
◆ Mitigation
● Reduces the effects of something, like an earthquake
● Natural disaster preparation
➔ More people are living on the coast
◆ Are more affected by natural disasters
➔ Economic losses from natural disasters
◆ Destruction and damage to structures
● Loss of productivity and wages
◆ Most expensive events typically caused by storms and occurred in US,
Europe, and Japan
◆ Industrial nations experience the worst economic loss (compared to poor
nations and developing nations)
➔ Greatest death toll in poor nations
find more resources at oneclass.com
find more resources at oneclass.com
◆ More people will die but it will be less economically damaging
Case study: 2010 Haiti earthquake
➔ Higher standards of living correspond to better construction, infrastructure, and
preparedness
➔ Haiti (7.0) caused 400x greater death toll that Chile earthquake (8.8)
◆ Poor infrastructure couldn’t withstand natural disasters
Natural hazards and the geological cycles
➔ Relating natural hazards to geologic cycles
➔ Geology determines type, location, and intensity of natural processes and
geologic hazards
➔ Subcycles: tectonic, rock, hydrologic, biogeochemical
➔ Tectonic cycle
◆ Refers to large-scale deformational processes
◆ Creation, destruction, and movement of tectonic plates
◆ Driven by forces within Earth (internal energy)
● 46,000 Gigawatts coming from inside the Earth
➔ Rock cycle
◆ Igneous rocks: form from crystallization of magma or lava
◆ Sedimentary rocks: rocks are weathered into sediment by wind, water, or
ice and lithified into sedimentary rocks
◆ Metamorphic rocks: changed through extreme heat, pressure, or
chemically active fluids
◆ Oceanic plate is pushed under a coastal plate
● Sedimentary rock from the oceanic plate is placed under heat and
pressure and metamorphic rock forms at the trench (margin where
one plate is being forced under the other)
● Metamorphic rock melts and crystallization of the molten rock
creates igneous rock
● Weathering of the rocks at the surface
● Erosion and transport to deposit sediment
● Lithification occurs under the ocean and creates sedimentary rock
➔ Hydrologic cycle
◆ External energy source: the Sun
◆ Explains how water moves around the atmosphere
◆ Hydrosphere to atmosphere
➔ Biogeochemical cycle
◆ Transfer of chemical elements through a series of reservoirs (spheres)
◆ Fossil fuels formed by plants decaying and covered by sediments
undergoing heat and pressure
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Processes: physical, chemical, and biological ways in which events affect earth"s surface. Internal processes come from forces within earth. External processes come from forces on earth"s surface. Result from external energy from the sun. Hazard: natural process or event that is a potential threat to human life. Potential for an earthquake or volcanic eruption. Examples: earthquakes, volcanoes, tsunami, climate change, fires, floods, impacts, mass extinctions. Disaster: hazardous event that occurs over a limited time in a defined area. Not an increase in earthquakes, but an increase in the human toll. Un 1990"s decade for natural hazards reduction . Reduces the effects of something, like an earthquake. More people are living on the coast. Most expensive events typically caused by storms and occurred in us, Industrial nations experience the worst economic loss (compared to poor nations and developing nations) More people will die but it will be less economically damaging. Higher standards of living correspond to better construction, infrastructure, and.
