Book 12, Question 103
Why Do Seismometers Listen for Magma Earthquakes?
Seismometers listen for magma earthquakes because moving magma and hot fluids shake the rock around them. Each kind of shaking has its own signature. A change in the pattern can mean the volcano is waking up.
More fun facts
- As magma moves underground, it pushes aside and breaks rock along the way.
- Breaking rock makes small earthquakes that seismometers can detect.
- Volcanic quakes are usually shallower than 10 kilometers and smaller than magnitude 3.
- They often come in swarms.
- Harmonic tremor is a steady, rhythmic shaking linked to moving magma.
Sources: U.S. Geological Survey, U.S. Geological Survey
Questions kids ask
What is harmonic tremor?
Continuous, rhythmic shaking caused by magma moving underground.