Discovered by Danish seismologist Inge Lehmann in 1936, this discontinuity is the boundary between the liquid outer core and the solid inner core. She proved the inner core’s existence by showing that P-waves were being reflected and refracted by a ...
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Megathrust earthquakes are the planet’s most powerful seismic events, occurring only at subduction zones. They happen at the interface where an oceanic plate is forced under a continental or another oceanic plate. These quakes are the only ones capable of ...
Charles Richter developed his scale using the maximum amplitude (height) of the largest wave recorded on a Wood-Anderson torsion seismograph. It was originally designed only for shallow earthquakes in Southern California, using a base-10 logarithmic calculation to handle the wide ...
Attenuation is the weakening of seismic waves as they move away from the source. This happens because the energy spreads over a larger area (geometric spreading) and is absorbed by the rocks (frictional heating). High-frequency waves attenuate faster than low-frequency ...
A tiltmeter is a sensitive instrument used to measure very small changes in the vertical level of the ground. It can detect the “bulging” or “tilting” of the Earth’s crust that often occurs when stress accumulates along a fault line ...