Seismic waves in Sichuan spread across the globe

Seismic waves generated from the devastating earthquake in Sichuan spread across the Earth's surface twice, according to Matsumoto Seismic Observatory of the Japan Meteorological Agency.

Illustration of seismic waves generated from the Sichuan earthquake.

According to Matsumoto Station, usually only seismic events with magnitude of 8 or more will cause this phenomenon.

Matsumoto Station said the Sichuan earthquake occurred at 15h28 (Japanese time), and at 15:41, the station's seismic detector detected seismic waves lasting about 2 minutes under the Earth's surface.

They move in the middle of the Earth's surface at a depth of 100 km (compared to the ground). The seismic wave then appeared at 1810 and 2040 on the same day.

According to the radio, seismic waves spread to Japan and then to South America and Africa and returned to Japan. Naoya Mikami, director of the station, said seismic waves originating in China have experienced a total length of 80,000 km, twice the circumference of the Earth, probably because their energy is so large that they can be long maintenance.