Residents of the bay area of California were shaken awake today as a result of a strong 4.5-magnitude earthquake. The earthquake was centered below Berkeley, California and was a result of movement along the Hayward fault, according to the USGS.
The earthquake began at 2:39 a.m. local time, located directly over the Claremont Hotel in Berkeley, which woke many residents of Berkeley and nearby cities. Residents across the San Francisco Bay area, as far south as San Jose, and as far north as Santa Rosa said they felt shaking. At this time, there are no significant reports of personal injury or structural damage and no threat of a tsunami.
The USGS classified the earthquake as moderate, occurring 8 miles into the earth, but warn there could well be small aftershocks in the coming days. They estimate that the probability of another strong earthquake striking the bay area is between 5% and 10%.
USGS
Locals say they felt shaking for 5 to 10 seconds and became worried about structural damage to their homes. However, magnitude 4.5 earthquakes often don't result in significant structural damage but are certainly powerful enough for people to take notice.
The earthquake was a result of movement on the Hayward fault, which runs right through Berkeley to the east of San Francisco. The fault runs roughly parallel to the San Andreas Fault, which lies to the west of the Berkeley fault. The Hayward fault, as it runs south, eventually merges into the Calaveras fault. This suggests any movement on the Hayward fault could translate to movement on the Calaveras fault to the south.
Felt a big jolt and rolling. Picture frames, etc, fell down. We are standing outside because the fire alarm went off. SFPD & SFFD is here now. #earthquake pic.twitter.com/8dMu58spUt — Riya (@loislane28) January 4, 2018
The origin of the Hayward fault is the constant northwestward sliding of the Pacific Plate at 5 millimeters per year against the North American Plate, producing a transform boundary. This transform boundary results in the San Andreas fault along with the Hayward fault. This constant movement between the two tectonic plates is experienced through sticks and slips between two fault planes. As strain builds up against the system of strike-slip faults, eventually the rock fails and there is fault displacement, i.e. an earthquake. Historically, the Hayward fault produces a large earthquake every 160 years, however, the margin of error (80 years) and little historical data makes predicting earthquake frequency difficult.
USGS
While it may not seem like a net positive, the fact that the Hayward fault slipped and produced a magnitude 4.5 earthquake is not entirely bad. The reasoning is that eventually, these faults (Hayward, San Andreas, etc.) will move. A worse case scenario is that enough strain is built up over time due to the lack of slip along the fault that it triggers a massive earthquake at magnitudes 9 and above.
The fact that the Hayward fault produced a magnitude 4.5 earthquake means it has, albeit temporarily, reduced strain on that part of the fault without further building up. Given a magnitude 4.5 earthquake is large enough to be felt but not large enough to cause significant structural damage or injury is in an ideal zone with regards to releasing strain on the system.
The potential for the Hayward fault to produce a 7.0 magnitude earthquake is there. In addition, the fault lies directly below approximately 2 million people, substantial infrastructure, as well as water, gas, and electric lines. While some other faults may have the potential for more substantial earthquakes, the location of the Hayward fault makes it one of the most dangerous in the United States.
While we can be assured that California will continue to experience earthquakes like the one today, we can hope they are regular and at small enough magnitudes as to not cause significant destruction.
An estimated 9.8 million people felt a magnitude 4.4 earthquake that rumbled across the Bay Area early Thursday, the U.S. Geological Survey reported.
It was felt throughout the region, with people more than 150 miles away reporting to the agency that they felt the shaking for perhaps five to 10 seconds, according to officials. Near San Francisco International Airport, several jolts could be felt.
According to responses on the USGS website, more than 9.8 million people were in the zone that could feel weak, light or moderate shaking. The earthquake was downgraded to a magnitude 4.4 after initial data suggested it was larger.
RELATED: The U.S. Geological Survey refers to the Hayward Fault as a "tectonic time bomb."
Items in a San Leandro store were knocked off the shelves, video from KRON4 showed, and Bay Area Rapid Transit started Thursday with train delays as workers performed a system-wide check for damage about 4 a.m.
The checks were completed about 5:30 a.m. with no reports of damage, the agency tweeted.
The earthquake was centered along the Oakland-Berkeley border, just north of the Claremont Hotel. The epicenter of the earthquake is in the area of the Hayward fault, one of the most feared in the Bay Area, which could produce a magnitude 7 or greater earthquake and is directly underneath heavily populated areas.
San Francisco’s emergency managers said all city facilities and infrastructure would be inspected Thursday, though there were no initial reports of damage or injuries.
A magnitude 4.5 earthquake is not expected to cause major damage, said U.S. Geological Survey seismologist Robert Sanders. Still, “there’s always a possibility of some minor damage to older structures in the area.”
The shaking was strong enough to wake people up when the earthquake hit at 2:39 a.m. One person in San Francisco said it was strong enough to knock picture frames from the wall.
As is always the case, there was a 5% chance the temblor could trigger a larger quake in the near future.
“We live in earthquake country so we should all expect earthquakes,” said Keith Knudsen, deputy director of the USGS Earthquake Science Center. “There will likely be aftershocks. There’s a small probability there will be bigger ones.”
An earthquake early warning system under development worked — and sent data about the temblor to computers 4 seconds after it began, Knudsen said.
In a real-world scenario, the jolt felt Thursday would likely not be considered big enough to issue a warning to residents in the path of the shaking, he said.
“But having one up and running and testing it is really valuable to us. How much warning time one gets depends on how far away they are, how big it is, how dense the seismic network is and how rapidly the computers are processing,” he said.
The system would typically allow a few seconds of warning for people not close to the epicenter — which would be enough time in theory to slow trains, stop elevators and allow people to brace themselves.
When asked Thursday at a news conference whether Californians were ready for an earthquake, Knudsen demurred.
“I’d ask you are you prepared?” he said. “We’re doing better than we used to do. But there’s more that can be done.”
The earthquake was felt as far away as Marin and Sonoma counties, and the Silicon Valley. Some Bay Area residents reported that the earthquake woke them up.
“Only M4.5, the size we have several times a year in California,” tweeted Jones. “But when you are right on top of a quake, it feels much stronger.”
The Hayward fault courses right underneath Berkeley, Oakland, Hayward and Fremont and produces a large earthquake, on average, every 160 years, with a margin of error of about 80 years. It has been 150 years since the Hayward fault last ruptured, unleashing a huge earthquake.
The Hayward fault’s most memorable earthquake in recorded history was in 1868, and is estimated to have been a magnitude 6.8 earthquake — rupturing 20 miles of the fault’s length between San Leandro to what is now the Warm Springs neighborhood of Fremont, according to the USGS. It killed about 30 people and caused immense property damage, including the collapse of the Alameda County Courthouse’s second floor and heavy damage at the historic Mission San Jose adobe church in southern Fremont.
USGS Geologist David Schwartz says Thursday morning quake occurred on seismically active 'hot spot' on Hayward Fault USGS Geologist David Schwartz says Thursday morning quake occurred on seismically active 'hot spot' on Hayward Fault SEE MORE VIDEOS
The Hayward fault is considered one of the nation’s most dangerous faults because it is located directly under the urban centers of the East Bay, including Memorial Stadium at UC Berkeley and a now-shuttered building that formerly housed Hayward City Hall, which is slowly being torn up by fault movement.
A USGS scenario for a 7.0 earthquake on the Hayward fault envisions it rupturing for 52 miles from San Pablo Bay to Fremont. It would cause one side of the fault to move four feet from the other. Many buildings, including apartments, still sit directly on top of the fault line, and were built before a state law passed in 1972 prohibiting new construction or substantial renovation on top of earthquake faults.
On its website, the USGS calls the Hayward fault the region’s “tectonic time bomb,” which could “cause hundreds of deaths, leave thousands homeless and devastate the region’s economy.”
In 2016, David Schwartz, a U.S. Geological Survey geologist, said in an interview that above the Hayward fault are “two million people who directly live on top of it. It sits geographically in the center of the Bay Area. There’s a tremendous amount of infrastructure built up on it — water systems, gas, electrical, BART crosses it — so a large event on that fault is like hitting the bull’s eye on a target.”
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San Francisco (CNN) A 4.4 magnitude earthquake struck early Thursday in Berkeley, California, according to a preliminary report from the US Geological Survey, jolting some residents of the densely populated San Francisco Bay area awake in their beds.
The earthquake hit at 2:39 a.m. local time (5:39 a.m. ET), centered near the Berkeley-Oakland boundary.
There were no immediate reports of damage in the area, the state Governor's Office of Emergency Services said.
No reports of damages from the region at this time. #earthquake #whatsshakincalifornia https://t.co/cSPgzjoMb5 — Cal OES (@Cal_OES) January 4, 2018
Some residents in the area told CNN affiliate KPIX that the quake shook them awake. A quake of this intensity generally would produce moderate shaking felt by nearly everyone near the epicenter, awakening many people and having the potential to break some windows and dishes, the USGS says
"It shook our house and shook the bed big time," Gina Solis of San Rafael, across the San Francisco Bay from Berkeley, told KPIX
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Residents in the San Francisco Bay Area were shaken awake in the early hours of Thursday morning after a magnitude-4.4 earthquake hit the region.
The quake's epicenter was on the eastern edge of Berkeley at a depth of eight miles, according to the United States Geological Survey, hitting just after 2:30 a.m. local time (5:30 a.m. ET).
It was initially reported by the USGS as a magnitude-4.7 event before being quickly downgraded.
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NBC Bay Area Chief Meteorologist Jeff Ranieri said it lasted around 10 seconds.
There were no immediate reports of damage or injuries, but enough people tweeted they felt the tremor to make #earthquake the top trending topic worldwide.
Berkeley Mayor Jesse Arreguin said he would be monitoring for damage and told people to be wary of aftershocks.
In the event of an #earthquake while sleeping, stay in bed, cover you head with a pillow until the shaking stops. Today's #Berkeley quake measured a preliminary 4.4 near Claremont in the hills. We will be monitoring any damage reports, and always be cautious of aftershocks. — Jesse Arreguin (@JesseArreguin) January 4, 2018
Others reported that the earthquake set off alarms and knocked items from shelves.
Felt a big jolt and rolling. Picture frames, etc, fell down. We are standing outside because the fire alarm went off. SFPD & SFFD is here now. #earthquake pic.twitter.com/8dMu58spUt — Riya (@loislane28) January 4, 2018
#Earthquake took out some items at San Leandro Safeway pic.twitter.com/GiXiaputFi — John De Motto (@johnDemotto) January 4, 2018
