Plate Boundaries
What is a subduction zone?
When an oceanic plate moves under a continental plate at a convergent boundary
What is the name of the machine that records seismic waves?
a seismograph
Name two of the three types of volcanoes
cinder cones, composite and shield
Tectonic plates
What kind of plate boundary causes the most earthquakes?
Transform
Name one piece of evidence that proves plate tectonics are real
Fossils, mountains, glaciers
What way do plates move at a normal fault?
Away from each other
Why does liquid rock flow upward out of a volcano?
Because it is in an area of high pressure and is less dense than solid rock
What layer makes up most of the earth? (84%)
the mantle
What is the large divergent plate boundary in the atlantic, that is responsible for seafloor spreading called?
The Mid-Atlantic Ridge
Which kind of boundary causes the most earthquakes?
transform
Why do you need three cities to determine the epicenter of an earthquake?
They need to all intersect, if you only used two you would have two possible epicenters
How does a convergent plate boundary create volcanoes?
the oceanic plate subducts under the continental plate it melts into magma and gets pushes upward
What two metals are the inner core made up of?
nickel and iron
Who was the scientist that came up with the theory of plate tectonics?
Alfred Wegener
What happens at a transform plate boundary?
The plates slide past each other
P waves- side to side (back and forth)
S waves- up and down
Describe how a hot spot made the state of hawaii
as the crust moves over the hot spot a volcano forms, then as it continues to move that volcano becomes an island and a new volcano forms under the hot spot
How thick is continental crust?
25 miles
Convergent
What kind of plate boundary is responsible for sea floor spreading?
divergent boundary
What are the Mercalli and Richter scales? What do each on of them measure?
Mercalli- damage done to buildings and how bad people felt the earthquake was
Richter- How much the earth is actually shaking
What kind of rock forms when magma that has a low viscosity and low amounts of silica?
Basalt
Which layer of the earth was first thought to be a liquid but is actually a solid?
outer core
What are magnetic stripes and how do they provide evidence for sea floor spreading?
As rock cools the magnetic pieces in it line up with the earth's magnetic field. The magnetic field switched direction every few years and the rock around the mid ocean ridge shows that