Two in one day: It’s not that unusual

Myanmar also experienced a quake

The powerful earthquakes that rocked Italy and Myanmar hours apart Wednesday were in no way related but show how seismically volatile our planet is.

Earth is rocked each year by more than 100,000 earthquakes with a magnitude- 3 intensity or greater, and hundreds of smaller quakes move the ground beneath our feet every day — many too small for humans to even feel.

The shaking is caused when the planet’s tectonic plates suddenly slip along a fault line.

The plates are always slowly moving, but sometimes their edges become stuck because of friction.

That stress puts pressure on the plates that is released in waves that travel through Earth’s crust and up to the ground beneath our feet — an earthquake.

Humans typically don’t feel the shaking until it reaches a magnitude- 3 or greater.

It’s not unusual for powerful quakes of a magnitude- 6 or greater to occur in two vastly separate places in the world on the same day, said U. S. Geological Survey geophysicist John Bellinni. There are about 100 quakes at that strength or higher each year worldwide, averaging out to about two powerful temblors per week.

Wednesday’s quakes occurred in two completely different seismic zones, Bellinni said, and at locations more than 5,000 miles apart. Italy’s quake struck at a magnitude- 6.2, killing scores of people. The one in Myanmar measured even higher at 6.8, and three people were reported to have been killed.

The disparity is a result of the fact that deeper quakes tend to do less damage. That’s because the strength of shaking from an earthquake diminishes the farther you get from its source, meaning the strength of shaking at the surface from a 300- mile deep quake is considerably less than a 12- mile deep one, the USGS said.

Italy’s quake occurred at a depth of about 6 miles below the surface, and Myanmar’s took place about 50 miles underground, said Susan Hough, a USGS seismologist.

Italy is a seismically active region, and that quake occurred along a boundary where the tectonic plate of Africa crashes into the European plate, Bellinni said.