Earth’s Layers & Plate Basics
This solid outer layer of Earth is broken into tectonic plates.
What is the lithosphere?
This type of boundary forms when two plates move apart.
What is a divergent boundary?
The point underground where an earthquake begins.
What is the focus?
This instrument records seismic waves.
What is a seismograph (or seismometer)?
These underwater mountain chains form at divergent boundaries in the ocean.
What are mid-ocean ridges?
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This softer, hotter layer beneath the plates allows them to move.
What is the asthenosphere?
This process happens at mid-ocean ridges when new crust forms as magma cools.
What is seafloor spreading?
These are the fastest seismic waves and arrive first.
What are P waves?
This older scale measures magnitude using the size of seismic waves.
What is the Richter scale?
This landform can form on land at a divergent boundary when the crust stretches and sinks.
What is a rift valley?
Tectonic plates move due to these circular currents in the mantle.
What are convection currents?
This happens at convergent boundaries when an oceanic plate sinks beneath a continental plate.
What is subduction?
These slower waves cause side-to-side and up-and-down shaking but cannot travel through liquids.
What are S waves?
This modern magnitude scale measures total energy released by an earthquake.
What is the Moment Magnitude scale?
This famous mid-ocean ridge runs down the center of the Atlantic Ocean.
What is the Mid-Atlantic Ridge?
These large pieces of Earth’s crust move about as fast as your fingernails grow.
What are tectonic plates?
This famous mountain range formed from the collision of the Indian and Eurasian plates.
What are the Himalayas?
These waves travel along Earth’s surface and cause the most destruction.
What are surface waves?
This scale uses Roman numerals to describe earthquake damage and what people feel.
What is the Modified Mercalli scale?
This South American mountain range formed due to subduction under the continent.
What are the Andes?
This scientist proposed the original idea that continents were once joined but couldn’t explain how they moved.
Who is Alfred Wegener?
This famous transform fault in California is known for frequent earthquakes.
What is the San Andreas Fault?
A giant ocean wave caused by an underwater earthquake.
What is a tsunami?
This term describes smaller quakes that follow the main earthquake.
What are aftershocks?
This mountain, still growing today, is the tallest on Earth and formed from continental collision.
What is Mount Everest?