OSLO -- Earthquakes from Italy to Pakistan that have killed at least 48 people in the past week are just part of the planet's routine but often devastating rumblings, and are not connected, seismologists said.

The deaths of 26 children in southern Italy when their school collapsed on Thursday caused international shock and made it seem that subsequent quakes in Indonesia, Pakistan, the United States and Japan were part of a freak chain.

But seismologists were unanimous: The earth is not going into a sudden spasm. People who live on geological fault lines, such as in San Francisco, California, are no more at risk than they were before, Reuters reported.

"There is not direct relation, no cause and effect. What we have is a planet that is very seismic. It has always been very seismic," Enzo Boschi, Director of Italy's National Institute of Geophysics and Vulcanology, said.

"It's more or less a coincidence. Earthquakes happen all the time," echoed Jorg Schlittenhardt, physicist at the German Seismic Data Analysis Center in Hanover.

Scientists said there were about 1,000 quakes a year, or two or three a day, of between 5.0 and 5.9 on the Richter scale -- a magnitude that experts say usually causes little damage to well-constructed buildings. Quakes in Italy, Pakistan and Japan were below 6.0.

In Pakistan, at least 17 people died in the mountainous north and 2,000 were displaced by quakes on Saturday with the biggest measuring 5.6 on the Richter scale.

The Italian quake, the worst in Italy since 1997, measured 5.4. apart from the dead six-and seven-year-olds, a teacher and two elderly women were killed to give a toll of 29.

And at least two people died and 5,300 were made homeless in a bigger 7.5-7.7 magnitude quake near Indonesia's Sumatra island on Saturday. Quakes in Alaska and Japan caused no fatalities.

More Vulnerable Scientists say that the globe's rising population may make damage greater as people cram into slums in ever-bigger cities.

"The increase in population makes us more vulnerable," said Hilmar Bungum at the Norwegian Norsar Seismic Institute.

In the past century, about 1.6 million people have died in earthquakes. The worst was in Tangshan, China, in 1976 that killed about 240,000 people.

Quakes are caused when continent-sized tectonic plates deep under the earth's surface, that move at about the speed finger nails grow, bump together. Scientists have found no reliable way to predict quakes.

"The (recent) quakes happened along different tectonic plates, therefore they cannot be related," said Fauzi (eds: one name), the Jakarta-based coordinator for Indonesia's meteorology and geophysics agency.

The Alaskan quake, the biggest in the past week at 7.9 on the Richter scale, damaged highways and forced closure of the trans-Alaska oil pipeline. But the only casualty in a remote, sparsely populated area was a 76-year-old woman who broke an arm while fleeing her home.

Seismologists say a tremor can cause others nearby -- the Alaska quake followed one in the region on October 23.

"We can sometimes see increases in seismicity around larger earthquakes, but we can't say that will increase seismicity in other parts of the globe," said Paul Whitmore, geophysicist for the West Coast & Alaska Tsunami Warning Center.

The U.S. geological survey estimates that the number of big earthquakes has remained fairly constant or may even have decreased in the late 20th century.

Small quakes can often be most devastating if they hit areas with poor construction standards. About 12,500 people died in Agadir, Morocco, after their homes collapsed in a tremor measuring just 5.9 on the Richter scale in 1960.