Aftershocks have hit the region between Northern California and Nevada Friday after a magnitude 6 earthquake sent large boulders rolling into highways and knocked smaller items off shelves.

The quake shortly before 4 p.m. Thursday was centered south of Lake Tahoe near Walker, a rural community of a few hundred households in the eastern Sierra Nevada. It was felt as far off as Las Vegas and San Francisco, authorities said. Days of aftershocks are expected.

California state emergency crews worked overnight and found minor road damage but no significant impacts to infrastructure, said Brian Ferguson, spokesman for the California Governor’s Office of Emergency Services. No injuries were immediately reported.

An earthquake with a preliminary magnitude of 4.9 rattled much of inland Southern California on Friday evening but no damage or injuries were reported, the U.S. Geological Survey confirmed.

The quake struck just after 6:53 p.m. and was centered near Anza in a remote desert area of Riverside County, southeast of Los Angeles and not far from Palm Springs. However, it was felt as much as 100 miles from the epicenter, according to a U.S. Geological Survey website.

A minor earthquake struck the Southern California high desert on Saturday and was was felt across the region, the U.S. Geological Survey confirmed.

The USGS reports the 3.9-magnitude earthquake hit an area about 13 miles northeast of Barstow at 11:34 a.m. Saturday.

Authorities said there were no immediate reports of damages or injuries. People reported to the USGS that they felt light shaking as far away as Los Angeles and Indio.

Over the next week, Southern California has only a 27% chance of experiencing a third earthquake greater than magnitude 6, but a 96% chance of going through a tremor of magnitude 5 or higher.

Those precise probabilities were generated by scientists at the United States Geological Survey (USGS), using models based on longstanding principles of seismic behavior and decades of data on aftershocks from earthquakes.

The state agency in charge of earthquake study and preparation, as well as monitoring mining efforts in Oregon, could be shut down after going over budget for the second time in four years.

The Oregonian/OregonLive reports the Department of Geology and Mineral Industries, widely known as DOGAMI, will lose three staff members and the Governor’s office is considering whether the agency should continue to exist in its current form given its financial issues.

Deciding when it's safe for a building's residents to move back in after an earthquake is a major challenge and responsibility for civil engineers. Not only do they have to evaluate whether the building could collapse, but also whether it could withstand aftershocks of the same magnitude. The good news is, some promising research is being carried out in this field.

Scientists at EPFL's Applied Computing and Mechanics Laboratory (IMAC) have come up with a new method that can increase the accuracy of these types of assessments. It is based on taking measurements of a building's ambient vibrations, and can be used to enhance existing methods and speed the process for determining which structures are too fragile to live in. The study – by Yves Reuland (lead author), Pierino Lestuzzi and Ian F.C. Smith – appears in the January issue of Soil Dynamics and Earthquake Engineering.

(TNS) - With considerable fanfare, Los Angeles Mayor Eric Garcetti started the year by trumpeting a cellphone app that will instantly notify users in Los Angeles County when an earthquake of 5.0 or bigger begins to hit.

The pilot program, officially unveiled Jan. 3, can provide crucial seconds — even dozens of seconds — for people to duck and cover or otherwise take potentially lifesaving actions.

Dubbed ShakeAlertLA, it’s the first earthquake early warning system of its type in the country.

A magnitude-4.0 earthquake rattled the rural west side of the San Joaquin Valley early, the U.S. Geological Survey confirmed.

No damages were reported.

(TNS) - Would your house survive a massive earthquake?

Emergency management officials say the expected Cascadia subduction zone quake could shake the Rogue Valley so hard that houses could collapse or slide off their foundations, leaving thousands homeless, injured or worse.

Even newer houses built before 1993 could see enough damage that they become uninhabitable.

“We could see sustained shaking for two to five minutes that could cause significant damage,” warned Althea Rizzo, geologic hazards program coordinator for the Oregon Office of Emergency Management. “Almost all the older homes need some kind of retrofit.”

Researchers at Oregon State University say bridges and roads in the northwestern resort city of Seaside should be prioritized for improvement after a simulation discovered they would have higher mortality rates in an earthquake and tsunami.

Researchers found that the bridge on Broadway Street over Neawanna Creek would result in the most fatalities, The Daily Astorian reported.