In the early 1900s, seismologists were monitoring and analyzing the Earth's seismic waves to better understand earthquakes and to probe the interior of the Earth. Richard Dixon Oldham's discovery in 1897 of P (primary) and S (secondary) seismic waves...

The core-mantle boundary (or CMB in the parlance of solid earth geophysicists) lies between the Earth's silicate mantle and its liquid iron-nickel outer core. This boundary is located at approximately 2900 km of depth beneath the Earth's surface. The...

It was a shot heard halfway round the world. In May 1992, an underground nuclear test in China punched a 1-second seismic pulse thousands of miles into the Earth. Meanwhile, scientists on the other side of the Pacific Ocean had their "ears" to...

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