Earth Spheres
A testable explanation for a set of observations.
What is a hypothesis?
The theory that Earth’s outer shell is divided into moving pieces called this.
What are tectonic plates?
The point inside Earth where an earthquake begins.
What is the focus?
Molten rock beneath Earth’s surface.
What is magma?
This is NOT the same thing as magnitude; it describes the effects of shaking at a location.
What is intensity?
When scientists start with a general principle and use it to predict a specific outcome, they are using this type of reasoning.
What is deductive reasoning?
The type of boundary where plates move away from each other.
What is a divergent boundary?
The time difference between P and S wave arrivals allows scientists to determine this.
What is distance to the epicenter?
A broad volcano with gentle slopes formed by fluid lava flows.
What is a shield volcano?
Earthquakes are NOT caused by weather but by movement along these structures.
What are faults?
When a volcanic eruption releases gases into the air, it is an interaction between these two spheres.
What are the geosphere (lithosphere) and atmosphere?
Magnetic stripes on the seafloor provided key evidence for this process.
What is seafloor spreading?
Waves that travel through Earth’s interior during an earthquake.
What are seismic waves?
Decompression melting is most commonly associated with this plate boundary type.
What is a divergent boundary?
Monitoring ground swelling and gas emissions near a volcano helps scientists predict this.
What is a possible eruption?
An Earth scientist who studies weather and climate.
What is a meteorologist?
The presence of identical fossils on widely separated continents was early evidence for this idea.
What is continental drift?
These seismic waves cannot travel through liquids.
What are S-waves (secondary waves)?
This factor largely determines whether a volcanic eruption will be explosive or quiet.
What is magma viscosity (or silica content)?
This volcanic hazard consists of fast-moving clouds of hot ash and gas.
What is a pyroclastic flow?
One major role of Earth scientists is helping society prepare for this type of natural event.
What are natural hazards (or natural disasters)?
The process where one plate descends into the mantle due to its higher density and collision with another plate.
The scale that measures earthquake magnitude based on seismic wave energy.
What is the Richter scale (or Moment Magnitude scale)?
These hydrothermal features erupt because groundwater is heated by magma and builds pressure underground.
What is a geyser?
This volcanic feature forms when a magma chamber empties and collapses inward.
What is a caldera?