Geophysical Hazards Flashcards
Explain what are plate tectonics
Are what make up the crust and are moved by convection currents.
Explain the process of convection currents
The hot rock rises by being heat up by the earths core. Then, they spread in two directions going sideways and cool down. The coool rock sinks causing the earths crusts to move apart.
Explain what are subduction zones
When an oceanic plates collides with continental plate and it is pushed down since it is less dense.Then, the rock melts which causes rock to rise causing a volcanic eruption.
Define + explain plumes
Outward flow of vocals rock from the center which creates a dragging force that pulls tectonic plates apart.
What are the primary volcanic hazards + explain them
- PYROCLASTIC FLOW—> fast mixture of lava, ash that spreads very rapidly.
- LAVA FLOWS—> molten rock putting and cools as it solidifies (fast-moving)
- PYROCLASTIC surges—> fast clouds of hot ash.
What are the secondary volcanic hazards
A. Lahars—> form of landslides (liquid mudflow), caused by heaving rains and ash
B. Landslides—> rocks separate from mountain sides because of earthquakes/volcanoes.
C. Tsunamis—> euription is in ocean
What is a focus?
The point of stores seismic energy of an earthquake
What is a epicenter
Located above the focus
Types of waves (earthquakes)
- BODY WAVES
A. P-waves —> compressional, faster
B. S waves—> sideways motion - SURFACE WAVES
A. Love ways —> sideways
B. Rayleigh waves
State the human triggers of earthquakes
- Dam constructions —> wight puts pressure on ground
- Mining —>instability of land as minerals are removed
- Fracking—-> drilling which cracks rock.
Sate secondary hazards of earthquakes
- Tsunami
- Landslides
- Liquefaction
Types of mass movements
- soil creeps
- avalanches
- landslides
- rockfalls
- mudflows
Causes of mass movements
- extended rains
- undercutting steep slope
- removal of vegetation
How is the risk management for earthquakes
(PLAN, PREPARE, PRIRITIZE)
- Improve infrastructure (resistant material uses to build houses) + resistant buildings checked by engineers)
- Prepare emergency kits (food water, medicine in houses)
- land zoning maps to identify risky places
- education: emergency drills to prepare individuals
How to measure earthquake freq+ magnitude
- richer scale —> measure seismic energy release (1—10)
- modified mercalli intensity scale—> Roman numerals represent intensity