Volcanos and Earthquakes Flashcards
Constructive Volcano
Creates new crust
Destructive Volcano
Climate, surrounding areas are destroyed by pyroclastic flow, lava
Pyroclastic Flow (size-l-s)
- Volcanic ash
- Lapilli
- Volcanic Bombs
- Volcanic Blocks
What makes magma explosive?
When the magma moves quickly to the surface, pressure decreases and water stays dissolved in the magma. Water becomes a gas and as the gases expand an explosion can occur
High Viscosity
Slow, stiff (Pahoehoe, Blocky)
Low Viscosity
Faster, more fluid (Aa, pillow)
Explosive Eruptions
Along the ring of fire (Mayon Volcanos, Aleution Islands)
Non-Explosive Eruptions
On seafloor and northwest regions of the U.S. (Mid atlantic ridge, Kilauea)
Shield Volcano
Built of layers of lava from nonexplosive eruptions, non steep sides can be enormous
Cinder Cone Volcano
Built of pyroclastic material produced from moderately explosive eruptions, steep slopes, occur in clusters
Composite/Strato Volcano
Form from explosive eruptions of pyroclastic material followed by quieter flows of lava, forms alternating layers of lava and pyroclastic material, broad bases and sides get steeper at the top, most common
Vent
Opening at the surface of the earth, through which volcanic material passes
Caldera
Forms when the roof a magma chamber collapses
Yellowstone National Park
2.2 million acres, the whole park is on top of a huge hotspot, on continental crust, blows up every 600,000 years, it blew up 630,000 years ago
How to explosive eruptions affect global climate change?
Pyroclastic material goes into the atmosphere and blocks the sun
Vesuvios
One of the few places where you can still see the remains of a natural disaster, debris fell for 2 days
Pelee
2 french survivors/ 350,00, blew up all sides of the volcano
Tambora
Ash covered 1 million miles
Santorini
Had an ash layer of 30 in.
Krakatoa
Largest sound ever recorded on Earth
Where do earthquakes occur?
Tectonic plate boundaries, 80% near the Pacific
Fault
A break in the Earth’s crust along which blocks of the crust slide relative to one another
Elastic Rebound
Sudden return of elastically deformed rock to its undeformed shape
P-Waves
Primary, can pass through solids, liquids, and gases on the entire Earth, fastest, back and forth motion
S-Waves
Secondary, can pass through solids, 2nd fastest, side to side motion
L-Waves
Surface, travel on the Earths surface, slow, most destructive,up and down motion
Seismograph
Instrument located at or near the Earth’s surface to record seismic waves
Seismogram
Tracing of earthquake motion created by seismographs
Triangulation
Locating 3 seismograph stations and finding the radius to draw a circle around each point. The point where they all meet is the epicenter
Epicenter
Closest point to the focus on the Earth’s surface
Richter
Measures strength (magnitude), measures ground motion and adjusts to find the strength, based on a factor of 10 for each level
Modified Mercalli
Measures intensity, measures in Roman Numerals I-XII (1-12), people take surveys to judge intensity, indicated total damage to an area
Deformation
Rocks changing shape due to stress from tectonic motion
Magnitude
Measures the strength of the ground motion
What structure forms as tectonic plates separate?
Rift Zone
When continental and oceanic crust collide what happens?
Oceanic crust sinks
