Earthquakes, Volcanoes, Floods Flashcards
Most earthquakes are caused by…
the buildup of strain associated with tectonic forces
The vast majority of earthquakes are tectonic or magmatic in nature, which explains why most earthquakes are found…
along plate boundaries
Artificial earthquakes
vibrational waves are generated from a human-derived explosions, trains, heavy equipment
Seismic waves
vibrational waves that travel through solid earth materials as seismic waves
Focus
where seismic waves originate
As seismic waves travel away from the focus, their energy is spread out over an ever-increasing volume of rock; this they become ___________
weaker
The eartquake with the more shallow focus would be ———— destructive than the deeper one
More
epicenter
point on the surface that lies directly above the focus
- Where strain energy is released
body waves
travel through earth’s interior
surface waves
body waves reach the surface and move along land surface
p-waves
(primary waves)
particles vibrate in the same direction the wave is travelling, causing rocks to compress and decompress
- fastest wave
s-waves
(secondary waves)
vibrate perpendicular to the wave path, making a shearing side-to-side motion
Mercalli intensity scale
method for comparing earthquakes based on human observations
- I to XII
Richter
measures wave amplitude
- 1-8
Several ———- earthquakes occur worldwide each year
several million
Earthquakes can cause…
- Liquefaction
- Landslides
- Tsumanis
- Fire
Liquefaction
Saturated loose sediment
Magma types
Granitic + Basaltic
(Rhyolitic, Andesitic) + (Basaltic)
Rhyolitic magma
- Hi Silica
- Low temperature
- High viscosity
- High water
Andesitic Magma
- Average i Silica
- Mid temperature
- Mid viscosity
- Average water
Basaltic magma
- Low Silica
- High temperature
- Low viscosity
- Low water
How would a basaltic volcano likely form?
- Divergent creates new ocean floor
- New crust = basaltic
- Basaltic volcanism will occur here
Types of basaltic volcanos
SHIELD VOLCANO
* Magma spreads long and thin
* Flat soda
CINDER CONES
* Magma turns to droplets that pile up
* Shaken soda
SO2
Causes global cooling
(Volcanic winter)
