the.com/seismic waves
the earth gossiping about its problems, one tremor at a time.
means energy pulses that travel through the earth's layers after an earthquake, revealing what's inside without ever digging a hole.
from from greek seismos, meaning shaking — first rigorously measured after japanese and european scientists built seismographs in the 1880s to catch the planet in the act.
p vs sp-waves arrive first, s-waves cant travel through liquid
earth's corediscovered because s-waves vanish there, proving it's molten
speedp-waves can hit 8 miles per second underground
moonquakesapollo seismometers proved the moon rings like a bell