The massive earthquake that tore apart a Chinese province this week is one of five huge temblors to rattle the world in April, so far. It follows quakes in Spain, the Solomon Islands, Sumatra and Baja California, Mexico.

The outburst comes on the heels of the deadly earthquake in Chile in February and a sizeable temblor in Los Angeles in March. A volcano erupting in Iceland has shut down air travel across a large swath of Europe. A volcano just erupted not far from Anchorage, Alaska. Shake after shake is making people quake.

Just what in the world is happening?

A few crack-ups in the Earth's teetering busboy act of tectonic plates, seismologists say.

"There's no increase in seismic activity, There's no pattern. Are they foreshocks to a catastrophically different earthquake? No," said Erin Beutel, director of the South Carolina Earthquake Education and Preparedness program at the College of Charleston.

So far this year, six earthquakes have rattled out a magnitude 7 or more on the Richter scale, about the strength of the Charleston quake. But that's not even a swarm. On average, there are 17 of those quakes that occur per year and 130 quakes that are 6 magnitude, according to the U.S. Geological Survey.

"In terms of geologic time that is an amazingly consistent number," Beutel said. The difference this time is people -- more of the powerful quakes hit places where a lot of people live. More attention has been paid to them, she said.

And last but not least, have there been any rumblings from the seismic faults under the Ashley River that cracked open the devastating 1886 Charleston earthquake? No.

"We've been looking," she said.

Reach Bo Petersen at 937-5744 or bpetersen@postandcourier.com.