When the island of Santorini was rattled by thousands of small earthquakes earlier this year, many people were left mystified ...

Most of what is known about what lies beneath comes from seismic waves — the vibrations of earthquakes traveling through and around the planet. Think of them as a giant sonogram of Earth.

The wave pattern seen on 11 November resembled these slow-moving waveforms usually seen following large earthquakes - only, in this case, there had not been a perceptible earthquake.

These mysterious waves, known as PKP precursors, arrive just before a type of seismic wave known as PKP waves, which travel through the Earth during an earthquake.

An earthquake is primarily measured by an instrument called a ‘seismograph’, which produces a digital graphic recording of the ground motion caused by seismic waves, called a ‘seismogram’.

Strange waves rippled around the world, and nobody knows why. Instruments picked up the seismic waves more than 10,000 miles away—but bizarrely, nobody felt them.

An earthquake is what happens when the seismic energy from plates slipping past each other rattles the planet's surface. Those seismic waves are like ripples on a pond, the USGS said.

Researchers have developed a new hybrid earthquake early warning system called HEWFERS, which leverages advanced machine ...

Each year, National Earthquake Information Center locates approximately 20,000 earthquakes around the world. That is about 55 earthquakes per day. By some estimates, there may be even more ...