EAS 210 - Midterm 2 Sample 2 Flashcards
What is the Richter magnitude of an earthquake based on?
The amount of ground movement caused by seismic waves
What happens when seismic waves encounter a boundary between two materials?
Some of the energy is reflected and some refracted at the boundary
What does the time interval between the arrival of P and S waves at a single seismic station reveal?
The distance to the earthquake
Where do the largest earthquakes on Earth occur?
Subduction zones
What is a Wadati-Beniof zone?
A zone of dipping earthquakes caused by a subduction zone
Old, cold and dense oceanic crust:
a. is created at spreading ridges
b. has ages up to 500 million years
c. eventually becomes incorporated into continental crust
d. can be felsic in composition
e. is destroyed at subduction zones
e. is destroyed at subduction zones
What is a passive margin?
A transition from oceanic crust to continental crust on the same tectonic plate
At what type of plate boundary do large mountain ranges (without volcanoes) form?
Convergent: continent-continent
When a deep-sea trench is located next to a continent, where can you expect to find active volcanoes?
On the adjacent continent
By what year was the current theory of plate tectonics widely accepted?
1970
What new evidence, discovered in the 1960s was used to support the theory of plate tectonics?
The discovery of magnetic strips parallel to the mid-ocean ridges
What is the main source of energy that moves the Earth’s tectonic plates?
Heat escaping from the Earth as it continues to cool.
What is the stage of a river measured in?
Meters
What is saltation?
The process by which sand grains are moved downstream in a river
Where does a medial moraine form?
Where two lateral moraines merge.
