Seismic Wave Basics
What is a seismic wave?
Energy that travels through Earth as a result of an earthquake or other disturbance.
What does the "P" in P wave stand for?
Primary.
What does the "S" in S wave stand for?
Secondary.
What are Earth's three main layers?
Crust, mantle, and core.
Which seismic wave arrives first at a seismograph?
P wave.
What causes most seismic waves?
The sudden release of energy during an earthquake.
Are P waves the fastest or slowest seismic waves?
Fastest.
Are S waves faster or slower than P waves?
Slower than P waves.
Which layer is mostly liquid?
The outer core.
Which wave can travel through solids, liquids, and gases?
P waves.
What instrument records seismic waves?
A seismograph or seismometer.
What types of materials can P waves travel through?
Solids, liquids, and gases.
Can S waves travel through liquids?
No. S waves cannot travel through liquids.
Which seismic wave cannot travel through liquids?
S waves.
Which wave causes the largest ground motion at Earth's surface?
Surface Waves.
What is the difference between an earthquake's focus and epicenter?
The focus is where the earthquake begins underground; the epicenter is the point directly above it on Earth's surface.
How does a P wave move through Earth's material?
They move by compressing and expanding material in the direction the wave travels.
How does an S wave move through Earth's material?
They move material perpendicular to the direction the wave travels.
How do seismic waves help scientists study Earth's interior?
By studying their speed, direction, and paths through Earth.
Why do scientists study the time difference between P-wave and S-wave arrivals?
The difference helps scientists determine how far away the earthquake occurred.
Why are seismic waves useful to scientists?
They help scientists locate earthquakes and investigate Earth's internal structure
Why can P waves travel through Earth's outer core?
Because P waves can travel through liquids.
What evidence shows that Earth's outer core is liquid?
S waves do not pass through Earth's outer core, showing that the outer core behaves as a liquid.
What happens to seismic waves when they encounter different materials inside Earth?
They can speed up, slow down, reflect, or refract when they encounter materials with different properties.
How can seismic-wave behavior provide evidence about the structure of Earth's interior?
Changes in wave speed, direction, and whether waves can pass through a layer provide evidence about the materials and physical state of Earth's interior.