U.S. & World

RENO, Nevada (CBS 5 / AP) ― Nearly 100 quakes, most imperceptibly small, have continued to be rattle the Reno area since a 4.2 magnitude quake was recorded Thursday afternoon, seismologists said Friday.

The 4.2 magnitude temblor shook Reno on Thursday afternoon, causing downtown buildings to sway and putting residents on edge throughout the city.

Some cracked windows and damaged roof tiles were reported in northwest residential areas but there were no reports of injuries or major damage.

The 4.2 temblor hit at 3:55 p.m. and was centered six miles west of Reno, the U.S. Geological Survey said. It shook downtown Reno for about 30 seconds and caused buildings to sway.

"It was unnerving," said Wanda Lopshire, who was working at the downtown Washoe County District Court building. "It physically moved my body. I could feel things shaking."

The Geological Survey said a 4.1 magnitude trembler hit minutes earlier at 3:47 p.m.

In addition to the two most powerful quakes, more than 30 other small earthquakes were reported during about a two-hour afternoon period, including seven registering 2.4 and above.

The University of Nevada, Reno's seismology laboratory reported the two largest quakes were "widely felt" throughout Reno and neighboring Sparks to the east. It said that based on the magnitude of the quakes, aftershocks could be expected for several days.

Stuart Smith, the head golf pro at Somersett Country Club located near the epicenter, reported "pretty violent shaking."

"Anytime you get a rattling like that, you are going to strike fear in some people," he said. "A couple of my employees were scared."

Only the two largest quakes were felt throughout Reno's downtown casino and business district.

The USGS revised it's report on the size of those two as more detailed information was available later in the day. It originally reported the biggest one was a 4.1. It then raised it to 4.2, then at one point as high as 4.4, but later reported it was a 4.2. The 4.1 quake initially was reported to be a 3.8.

"It shook the whole house real good," said Rick Dinoso, a resident of the northwest part of town that has been rattled by dozens of smaller earthquakes since the end of February.

"This was the strongest one in the last two months. I was wondering whether I should grab the kid and get under the table," he said. "You could see the sides of the house swaying."

Reno police spokesman Steve Frady said there were no reports of significant damage or injuries.

"We felt it over here, but nothing came off the walls," he said from police headquarters on the east edge of downtown. "The (police) radio has been relatively quiet considering."

The quakes around Reno occurred in an area where scores of smaller ones have been centered in recent weeks. Temblors of magnitude 2 and higher have been occurring about every three days since a swarm of widely felt earthquakes began Feb. 28, said John Anderson of the University of Nevada, Reno's seismology laboratory.

"Since April 15, there have been three a day," he said.

Anderson said the bulk of them appeared to be centered just west of Reno near the U.S. Interstate 80 interchange for Mogul.

Earthquake magnitudes are calculated according to ground motion recorded on seismographs. An increase in one full number - from 6.5 to 7.5, for example - means the quake's magnitude is 10 times as great.

A quake with a magnitude of 6 can cause severe damage, while one with a magnitude of 7 can cause widespread, heavy damage.

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