Book 12, Question 31
Why Can Sensors Feel Earthquakes That People Can’t?
Sensors can measure ground movements thousands of times smaller than anything a person can feel. Our bodies only notice shaking that is big enough to move us. Machines extend our senses, like a super-powered ear for the ground!
More fun facts
- In small daily earthquakes, only a short piece of fault slips, and people cannot feel the shaking.
- In a magnitude 5.0 quake, a mile or two of fault breaks, and people easily feel it.
- Mexico has a sensor network near the coast that broadcasts warnings to Mexico City.
- Scientists say there is no explanation for people who claim to sense quakes before they happen.
- Anyone who feels an earthquake can report it online to help scientists.
Sources: Scientific American, U.S. Geological Survey
Questions kids ask
Can some people sense quakes before they happen?
Scientists have found no explanation for it, and usually no quake follows.