lesson 8: geological processes

• geological processes


  naturally occurring events that directly or indirectly impact the geology of the earth.
• geological hazards


  extreme natural event in the crust of the earth that poses a threat to life and property.
• earthquakes


  are the result of a sudden release in energy that originates from elastically strained rocks beneath
• fault planes / fracturing rocks


  where earthquakes usually occur
• elastic rebound theory


  earthquakes may be understood through this theory.
• harry fielding reid


  he proposed the elastic rebound theory
• elastic rebound theory


  • has an explanation for the way that earthquakes behave
  • how the build up of strain energy in the deforming rocks over the sides of the fault may be released. the energy is released as a result of rebound (causes shaking.)
• richter scale


  measures the magnitude of the earthquake (force of the earthquake)
• mercalli scale


  measures the physical impact or intensity of the earthquake.
• epicenter


  location on the surface, is directly above the focus of the earthquake.
• focus/hypocenter


  actual location of earthquakes and where fracture happens
• ground movement


  also called ''ground shaking''
• ground movement


  happens when seismic waves pass near the epicenter of the earthquake.
• ground rupture


  occurs along the fault zone that moves during the earthquake.
• liquefaction


  result from the shaking of water-saturated, unconsolidated, or loosely packed sediments by ground shaking.
• P waves


  travel faster than other seismic waves, first signal from an earthquake
• S waves


  the second waves to hit the seismographs, they are transverse waves
• love waves


  a propagating shear mode wave supported on semiinfinite substrates
• rayleigh waves


  surface waves that travel near the surface of solid, include both longitudinal and transverse motions.
• tsunami


  it is the large waves that may generate after an earthquake, landslide, or volcanic eruption.
• tsunami


  major disturbance in a seafloor, 725 km/h
• effusive eruption


  • composed of low viscosity magma
  • lava flows are produced on the surface, which then moves downslope
• effusive eruption


  gas release
• effusive eruption


  low internal pressure
• effusive eruption


  lava flow
• effusive eruption


  fissure eruption
• effusive eruption


  pillow lavas
• explosive eruption


  magma that has high gas contents and viscosity
• explosive eruption


  when the explosion of gas bubbles breaks the magma into

  Iiquid clots, which solidify upon cooling.
• pyloclasts


  liquid clots which solidify upon cooling, these are also called "volcanic ash."
• explosive eruption


  high viscosity magma
• explosive eruption


  gas trapping
• explosive eruption


  high internal pressure
• explosive eruption


  explosive release
• plinian eruption


  occurs when a cloud of gas and tephra rise above the volcanic crater
• tephra


  fragments varying in size and composition released by volcanic eruptions
• phreatic eruption


  occurs when magma heats the overlyinh groundwater, causing rapid evaporation and the formation of steam.
• strombolian eruptiont


  when the internal pressure of gas bubble is low amd as a result, most of the pyroclastic material will fall close to the vent creating a cinder cone.
• pyroclastic flow


  • happens when the eruption cplumn collapses
  • gas and tephra (or rock fragments) move down rapidly
• volcanic mudflow/lahar


  • when loose debris mixes with rainwater, melted ice, or the draining of a crater lake.
  • can occur during and after an eruption
  • have high velocity, varying temperatures