Tectonic Plates Flashcards
Fault
Where two tectonic plates meet/ the boundary between them
Richter Scale
Scale used to measure the strength of earthquakes themselves
Tectonic Plate
Part of the lithosphere that is constantly moving because of convection currents in the mantle
Tsunami
Big wave, sometimes comes after earthquakes. It’s an ocean phenomenon that can be set off by sudden tectonic plate motion underwater.
Hotspot
A column of rising magma that breaks through the crust and makes volcanoes
Seismic Wave
Earthquake (intense movement created by sudden release of pressure from moving tectonic plates)
Mercalli Scale
A scale used to measure how much damage an earthquake caused (contrasted with the Richter Scale, which only measures seismic power)
Earthquake
Intense movement caused by a sudden release of pressure from moving tectonic plates
What happens at Convergent Boundaries?
Subduction or uplift zones. Both volcanoes and earthquakes form here. Reverse faults and compression.
Trenches, volcanoes, and island arcs are formed by convergent boundaries. Island arcs are between two oceanic plates and volcanoes are between one oceanic plate and one continental plate.
Convergent boundaries make the Pacific Ocean smaller. The Ring of Fire is an example of a convergent boundary.
What happens at Divergent Boundaries?
Both volcanoes and earthquakes form here, although the volcanoes are bubbly, pillow-lava-oozing structures. Normal faults (first one discovered) but tension (rubber band).
Seafloor spreading happens at a divergent boundary in the Atlantic Ocean. This is called the Mid-Atlantic Ridge, which is a mid ocean ridge. Since new land is being created, the Atlantic Ocean is becoming bigger.
Henry Hess is the seafloor spreading guy. Notice that pillow lava cools quickly because the bottom of the ocean is very cold.
What happens at Strike-slip Boundaries?
Only earthquakes happen here, NOT volcanoes. The stress is shearing and the fault is strike-slip, or transform.
The San Andreas fault is a famous example of a strike-slip boundary.
List evidence for Sea Floor Spreading
- The rock closest to the Mid Atlantic Ridge is newer than the rock farther away.
- You can find deep trenches far from these ridges. If seafloor spreading existed, the old crust would subduct into the ground and get recycled. That could be what occurs at these trenches.
- Something about magnetic strips and Earth’s polarity reversing that I do not understand at all
List evidence for Continental Drift
- Identical fossils found on opposite sides of oceans (the Earth used to be together, so there was no ocean separating them)
- Fossils found in places where they would not be able to survive because the habitat doesn’t suit them (the continents used to be in a different position, but since they moved, these habitats changed)
- Rock layers match up perfectly on opposite continents on opposite sides of the ocean (again, the continents used to be together)
- The continents fit together like puzzle pieces (no explanation required obviously)
- Seafloor spreading (proves that the continents are moving after all! If the continents are moving, it’s no surprise Pangea broke up.)
- Mountain ranges match up
Where are volcanoes/EQ located?
Both are found at every type of plate boundary except transform or strike-slip boundaries. This boundary only has earthquakes.
Pacific vs Atlantic
Pacific Ocean shrinking
Atlantic Ocean growing
