Japan earthquake was registered in several other countries within minutes, even Alaska

Japan's massive earthquake which shook the country on Monday at 4:10 pm local time and had a magnitude of 7.5 was immediately registered on the seismometers present in the near vicinity. It was also recorded within minutes across the world, which included North Carolina, as per a media report.

Earthquakes take place with an instant release of strain energy at the hypocentre below the surface of the Earth and are first felt at the epicenter which is directly above them. The quake that occurred on Monday was more than 6 miles beneath the Sea of Japan and close to the town of Suzu on the Noto Peninsula in Ishikawa prefecture.

The energy released during an earthquake travels outward in all directions in the form of waves – similar to ripples in a pond, along the surface of the Earth and through its core.

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Waves travelled throughout the world at different motions

Primary (P) waves are said to travel fasterand reach the seismometers first while the rocks are compressed horizontally. Shear (S) waves are the next ones to reach which deliver destructive up and down motion.

Seismometers are able to record both horizontal and vertical motion, however, the charts which are prepared include mostly destructive vertical components.

According to a sampling of seismometers which has been collected by the Incorporated Research Institutions for Seismology (IRIS), the earthquake was registered on a seismograph located in northern Alaska nearly nine minutes after it struck Japan.

After 12 minutes, the first seismic wave reached Casper, Wyoming and the waves then reached Pittsboro 14 minutes later at 2:24 a.m. EST.

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However, similar to waves which move outward after a pebble is tossed in a pond, seismic waves remain the strongest near the source. The speed of ripples, after getting recorded in Japan, reduced by a factor of several thousand times, after it reachedNorth Carolina.

After the first shock from the earthquake, the motion continues along the surface as well as through the core of the Earth. The seismometer in Pittsboro, as well as in other places across the world, continued recording this motion for many hours after the initial shock was felt.

(With inputs from agencies)