A 5.4-magnitude aftershock rattled Searles Valley Friday morning, less than 24 hours after a 6.4 magnitude quake in the area shook Southern California.

The aftershock occurred just after 4 a.m. about 10 miles west of Searles Valley, according to the United States Geological Survey. It was the strongest of the more than 200 aftershocks that followed Thursday morning's quake.

An aftershock of this magnitude was expected by experts following Thursday's temblor.

Dr. Lucy Jones, a seismologist and founder of the Dr. Lucy Jones Center for Science & Society, estimated during a news conference hours after Thursday's earthquake that there was a 50 percent chance an aftershock of 5.0 magnitude would strike Thursday afternoon.

More: One of the strongest earthquakes in years rattles Southern California, damaging areas of Kern County

"It’s certain this area is going to be shaking a lot today," Jones said on Thursday. "Some of those aftershocks will exceed magnitude five."

The last time Southern California had an earthquake greater than magnitude 6.0 was in October 1999. The magnitude-7.1 quake was centered about 30 miles north of Joshua Tree National Park headquarters and was felt in Nevada, Arizona and Mexico.

Both Thursday's earthquake and its strongest aftershock occurred about 170 miles northwest of Palm Springs. Local experts said there's no need for additional concern in the Coachella Valley.

“In general, the earthquake hazard is high in the Coachella Valley, but this particular earthquake is not a cause of additional concern for people in the Palm Springs area,” said Abhijit Ghosh, a professor of geophysics at the University of California, Riverside, on Thursday afternoon.

This article will be updated as more information becomes available. </s> SAN FRANCISCO (AP) — An earthquake rattled a large swath of Southern California and parts of Nevada on Thursday morning, making hanging lamps sway and photo frames on wall shake. There were no immediate reports of damage or injuries.

The 6.4 magnitude quake measured struck near in the Mojave Desert, about 150 miles (240 kilometers) northeast of Los Angeles, near the town of Ridgecrest, California.

The United State Geological Survey initially said it measured at a 6.6 magnitude.

People from Las Vegas to the Pacific Coast reported feeling a rolling motion and took to social media to report it.

Local emergency agencies also took to social media to ask people to only call 911 for emergencies.

"We are very much aware of the significant earthquake that just occurred in Southern California. Please DO NOT call 9-1-1 unless there are injuries or other dangerous conditions. Don't call for questions please," the LAPD said in a statement published on Twitter.

Ashleigh Chandler, a helicopter rescue EMT at Fort Irwin, California, said the quake happened as she was getting ready for a July 4th party.

"I was just in the living room getting everything ready, we start to feel the shaking, so then I look up and then the wine bottles start rattling and I thought, 'They're going to fall.'

"My sister was in the house and my dog, so we just got everyone outside and then it ended. It was like 15, 20 seconds, maybe. It was pretty good shaking, so I'm out of breath." </s> Southern California is earthquake country. But if you’ve lived in the area for the last couple of decades, you might not know it.

Despite Thursday’s wake-up call 6.4 magnitude in a remote desert area near the town of Ridgecrest, Southern California has been experiencing an earthquake drought, scientists said Thursday.

The relative inactivity did not go unnoticed by one high-profile expert on California’s shakers.

“I think this would be a good time to remind you that if you have been experiencing earthquakes for the last 20 years in California, you have been experiencing an extremely quiet time in California history,” Caltech scientist Lucy Jones said.

Take note of that history:

The last time there was an earthquake above magnitude 6 in Southern California was 1999, Jones said.

The previous decade leading up to that had about eight magnitude 6s.

“This has been an extremely quiet, abnormal time,” she said.

Jones said the quake that shook the region on Thursday was actually more “normal” for what we should be expecting in Southern California, based on historical averages.

A quake of the Ridgecrest size, based on long-term history, should be coming once every five or 10 years in Southern California.

Yet, you’d have to go back to Oct. 16, 1999, for anything bigger. That’s when a magnitude 7.1 quake hit about 32 miles north of Joshua Tree.

Until Thursday’s Ridgecrest quake, it was the largest tremor to have hit the area since the 7.3-magnitude Landers Earthquake struck on June 28, 1992. And just this year, the 25th anniversary of the 6.7-magnitude Northridge Earthquake was remembered, along with its tragic toll of 57 people killed.

Here’s a quick rundown on some others above 4.0 over the last 25 years:
• 6.4 magnitude earthquake in Southern California shakes social media with surprise reactions and videos
• LA has an earthquake warning system. It didn’t send an alert for the July 4th quake. So what does this all mean? Are we due? Is there energy building up on the faults throughout Southern California?

It may just come down to being aware.

Here’s what U.S. Geological Survey seismologist Robert Graves had to say about that: “Obviously any earthquake that occurs releases some of that tension. But there’s a tremendous amount that’s built up since the last major earthquake, which was in 1857 on the San Andreas.” </s> One day after Southern California experienced its strongest earthquake in 20 years, a 5.4 magnitude aftershock rattled the area once again early Friday morning.

The quake struck around 4:07 a.m. Pacific Time in the Mojave Desert, according to the U.S. Geological Survey. The aftershock was located 16 kilometers West of Searles Valley, California.

So far, it's the largest of a swarm of ongoing aftershocks to hit California following Thursday's 6.4 magnitude quake that also struck in the Mojave Desert and led Gov. Gavin Newsom to declare a state of emergency for one county.

Dramatic video on Friday showed a Good Morning America reporter caught in the aftershock while her camera was rolling.

When the earthquake struck on July 4, people from Las Vegas to the Pacific Coast reported feeling a rolling motion and took to social media to report it.

The Associated Press contributed to this report. </s> RIDGECREST, California — The magnitude 6.4 earthquake that struck an area of California between Los Angeles and Las Vegas on Thursday morning was the strongest quake to hit the region in 20 years.

The rolling temblor sent dozens aftershocks through the Fourth of July holiday and researchers say they could last for a week. A California official says some injuries and two house fires have been reported in a town near the epicenter.

The United States Geological Survey says on its website that their forecast over the next week includes a 9% chance of one or more aftershocks larger than the Thursday earthquake's magnitude 6.4. It is likely that there will be smaller earthquakes over the next week, with 50 to 700 magnitude 3 or higher aftershocks.

It happened near Searles Valley, California, about 125 miles northeast of Los Angeles and 125 miles west of Las Vegas. The 28,000 residents of Ridgecrest make up the biggest population concentration closest to the epicenter. The quake had a depth of 5.4 miles.

Kern County Fire Chief David Witt also told The Associated Press that emergency crews were dealing with small vegetation fires, cracks on some roads and gas leaks that were reported after the quake in the Mojave Desert.

The U.S.G.S. says magnitude 3 and above are large enough to be felt near the epicenter, and that the number of aftershocks will drop off over time. However, a large aftershock can increase the numbers again, temporarily.

The survey tweeted that at around 1:15 p.m. local time, nearly three hours after the mainshock, there were more than 100 aftershocks at least magnitude 2.5. It also said that hours later there had been over 22 that were strong enough to feel.

It was felt in neighboring states and was followed by dozens of aftershocks. Firefighters nearby reported responding to medical emergencies and fires.

Veteran seismologist Lucy Jones says the earthquake Thursday was the strongest to hit Southern California in 20 years.

She says the previous large quake was a 7.1 that struck in the area on October 16, 1999.

Jones told reporters at the California Institute of Technology in Pasadena that the 6.4 quake centered in the Mojave Desert near the town of Ridgecrest was preceded by a magnitude 4.3 temblor about a half hour earlier.

In Ridgecrest, Kern County fire officials reported responding to at least two dozen incidents ranging from medical assistance to structure fires.

People as far away as Phoenix -- nearly 350 miles away -- reported feeling it.

RELATED: Prepare to be on your own in a major disaster

A common feature of this quake people had reported was that it lasted a long time.

"The strange thing about this one is it kept rolling and rolling and rolling. It felt like it lasted a good minute," said NBC Nightly News anchor Lester Holt in a phone interview from Los Angeles.

"Bigger quakes last for a longer time. The fault was producing energy for about 5 seconds. What you feel is that plus reverberations," Jones tweeted.

An interactive map from the U.S. Geological Survey showed there were two quakes -- magnitude 2.5 and 4.0 -- in the same area within a half-hour prior to the larger one.

People jumped onto social media to talk about the experience, and President Donald Trump tweeted that he has been briefed on the situation.

Filmmaker Ava DuVernay said she's lived in Los Angeles her entire life and it was the longest earthquake she ever felt.

"Not jerky. Smooth and rolling. But it was loooong. It was so long I thought for the first time ever “Is this the big one?” Damn. Respect Mother Nature. She’s the boss," DuVernay tweeted.

Sports talk show host Colin Cowherd was in the middle of his show on FS1, based in Los Angles, and narrated what he was feeling.

In Las Vegas, some people described it as minor while others experienced more shaking. </s> LOS ANGELES (AP) — A strong earthquake rattled a large swath of Southern California and parts of Nevada on Thursday morning, making hanging lamps sway and photo frames on walls shake. There were no immediate reports of damage or injuries but a swarm of aftershocks were reported.

The 6.4 magnitude quake struck at 10:33 a.m. in the Mojave Desert, about 150 miles (240 kilometers) northeast of Los Angeles, near the town of Ridgecrest, California. It is the strongest quake to hit the region in 20 years.

The United State Geological Survey initially said it measured at a 6.6 magnitude.

"It almost gave me a heart attack," said Cora Burke, a waitress at Midway Cafe in Ridgecrest, a town of 28,000 people. "It's just a rolling feeling inside the building, inside the cafe and all of a sudden everything started falling off the shelf, glasses, the refrigerator and everything in the small refrigerator fell over."

Video posted online of a liquor store in Ridgecrest showed the aisles filled with broken wine and liquor bottles, knocked down boxes and other groceries strewn on the floor. There was at least one house on fire in Ridgecrest.

Veteran seismologist Lucy Jones said the earthquake Thursday was the strongest to hit Southern California in 20 years.

The previous large quake was a 7.1 on that struck in the area on October 16, 1999, she said.

Jones told reporters at the California Institute of Technology in Pasadena, California, that the 6.4 quake centered in the Mojave Desert near the town of Ridgecrest was preceded by a magnitude 4.3 temblor about a half hour earlier.

She says it was vigorous aftershock sequence occurring and that she wouldn't be surprise if a magnitude 5 quake occurred during the aftershocks.

"We should be expecting lots of aftershocks," she said.

People from Las Vegas to the Pacific Coast reported feeling a rolling motion and took to social media to report it.

Local emergency agencies also took to social media to ask people to only call 911 for emergencies.

"We are very much aware of the significant earthquake that just occurred in Southern California. Please DO NOT call 9-1-1 unless there are injuries or other dangerous conditions. Don't call for questions please," the LAPD said in a statement published on Twitter.

Ashleigh Chandler, a helicopter rescue EMT at Fort Irwin, California, said the quake happened as she was getting ready for a July 4th party.

"I was just in the living room getting everything ready, we start to feel the shaking, so then I look up and then the wine bottles start rattling and I thought, 'They're going to fall.'

"My stepson was in the house and my dog, so we just got everyone outside and then it ended. It was like 15, 20 seconds, maybe. It was pretty good shaking, so I'm out of breath."

Rodriguez reported from San Francisco. Associated Press writer Rachel Lerman in San Francisco and AP Radio reporter Shelly Adler in Washington, D.C., contributed.

The quote in the story from Ashleigh Chandler has been corrected to say stepson, not sister. </s> LOS ANGELES (WDTN) – A magnitude-6.4 earthquake has been reported Thursday afternoon in southern California, just north of of Los Angeles, according to the United States Geological Survey.

The epicenter of the earthquake occurred about 120 miles north, northeast of Los Angeles, near Searles Valley, Calif., at around 1:30 pm eastern time.

The extent of damage or possible injuries has yet to be determined.

Like us on Facebook and follow us on Twitter for all the latest news, weather and sports. </s> Southern California was rattled Thursday by a magnitude 5.3 earthquake that struck near the Channel Islands.

The quake was the strongest in Southern California in several years, jangling some nerves but causing no major damage because it occurred offshore in the Pacific Ocean and not on land.

The quake did cause some minor landslides and earth movement on Santa Cruz Island, which was close to the epicenter, and rattled a bald eagle whose livestreamed reaction to the temblor went viral.

“A 5.3 could be damaging if it was right under our feet,” said John Vidale, director of the Southern California Earthquake Center at USC. “It’s right on the edge of being an earthquake that could be dangerous. It’s a reminder that we need to be ready in the future.”

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The temblor occurred just before 12:30 p.m. and was centered south of Santa Cruz Island, about 90 miles west of downtown Los Angeles. It was felt as far away as Bakersfield, Palmdale and the city of Orange, according to witnesses and the U.S. Geological Survey.

Earthquake early-warning system gave heads-up before 5.3 magnitude temblor hit L.A. area »

The L.A. area feels an earthquake of this magnitude on average about once a year, Vidale said.

There is a 1-in-20 chance that Thursday’s quake will lead to a larger one in the next few weeks, he said. But, more than likely, smaller aftershocks that may not even be felt will follow, he said.

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The quake was too small and too far away from the coast to trigger any tsunami concerns.

“It would never make a wave that you could see,” Vidale said.

(Los Angeles Times )

But it was large enough to activate the state’s developing earthquake early-warning system.

Vidale said he and colleagues at USC heard beeping 10 to 15 seconds before the quake’s shaking reached their campus.

“We all felt it pretty well. It was small and distinct,” he said. “We heard the warning go off and then we heard the shaking.”

The early-warning system is under development by the USGS and is available only to a limited array of testers, but it is expected that more people will be eligible to test the system later this year.

It works on a simple principle: The shaking from an earthquake travels at the speed of sound through rock — which is slower than the speed of today’s communications systems.

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For example, it would take more than a minute for a magnitude 7.8 earthquake that starts at the Salton Sea and travels up the state’s longest fault, the San Andreas, to shake Los Angeles, 150 miles away. An early-warning system would give L.A. residents crucial seconds, and perhaps even more than a minute, to prepare.

It got a significant boost in the federal budget signed into law in March, defying an earlier proposal by President Trump to end federal funding for the program.

As part of the $1.3-trillion budget bill approved by Congress and signed by Trump, officials approved $22.9 million for the project. That more than doubles the $10.2 million it got in the previous year’s budget.

The USGS has said it planned to begin issuing limited public alerts from the system by the end of this year, as long as funding wasn’t cut. Southern California is one area where the network of seismic sensors is dense enough at present to begin early warnings.

That was the first earthquake I’ve felt since I got access to the @EarlyWarningLab beta app. I had 34 seconds warning—enough time to drop, cover, and hold on, which I would have done if I knew shaking was going to be strong. pic.twitter.com/Bx4Sn2imUW — Alissa Walker (@awalkerinLA) April 5, 2018

Earthquake that rattled L.A. area was strongest in years »

The temblor was located near the East Santa Cruz Basin fault zone, said Caltech seismologist Egill Hauksson, and seismologist Lucy Jones said on Twitter that the fault system “moves Southern California around a bend of the San Andreas fault.”

“Earthquakes happen out there now and again. There’s a major offshore fault system,” Hauksson said.

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When asked why some people felt the earthquake but others nearby didn’t, Hauksson said where a person is matters a lot. “People in high rises probably felt it pretty well,” he said. People on softer soils might also feel stronger shaking.

Among those creatures startled by the quake were the feathered inhabitants of a bald eagle’s nest high above Santa Cruz Island.

A National Park Service live web camera trained on the nest shows a parent eagle and three chicks as their tree begins shaking. The parent flies off as the chicks look around bewildered. The parent eagle returns moments later, after the shaking.

WATCH: Eagle and chicks on Santa Cruz Island react to 5.3 Channel Islands earthquake https://t.co/Tm7D67mSgP pic.twitter.com/AwvVf6823b — CBS Los Angeles (@CBSLA) April 5, 2018

One of the last quakes to be felt this widely in the L.A. area was a magnitude 4.4 in Encino in 2014. That quake also shook a wide area and was the largest in the Los Angeles area in four years. It was noted by seismologists as the strongest to hit directly under the Santa Monica Mountains in 80 years.

Another widely felt earthquake came later that same month, a magnitude 5.1 centered in La Habra. Residents close to the epicenter reported toppled furniture, broken glass and fallen pictures; several water mains broke, a rock slide caused a car to overturn, and more than a dozen homes and apartments were declared uninhabitable because of possible structural damage.

The last time an area earthquake produced more energy than Thursday’s temblor was in 2012, when a magnitude 5.4 earthquake struck the border town of Brawley in Imperial County. Local officials reported 20 mobile homes shifted from their foundations and cosmetic damage to downtown buildings.

The epicenter of Thursday’s quake was south of the Channel Islands. A magnitude 4.8 quake in the same area rattled the region in 2013, but that epicenter was much closer to the coast, three miles away from Isla Vista, and produced moderate shaking enough to knock down a few photo frames.

A park service spokeswoman told KEYT that Thursday’s quake sent some bricks toppling off a chimney from a historic ranch property built in the 1860s on one of the islands.

The Santa Barbara area is home to a number of earthquake faults, the largest of which is the Santa Ynez fault, which is 80 miles long and runs just north of the city. That fault is believed to be capable of triggering an earthquake as powerful as magnitude 7.5.

Get ready for a major quake. What to do before — and during — a big one »

The great Santa Barbara quake of 1925, recorded at a magnitude 6.8, destroyed much of the city’s downtown on State Street, damaged rail lines, caused extensive landslides and was felt as far away as Orange County. It killed 13 people.

Since the magnitude 7.2 Easter Sunday earthquake of 2010 that hit along the California-Mexico border, there have been 14 earthquakes of magnitude 5 or greater in Southern California. Hauksson estimated that perhaps about half of them were felt in Los Angeles.

Seismologist Lucy Jones said she received a complaint Thursday about her calling earthquake activity like this normal. Some people on Twitter asked her what the larger meaning was behind the earthquake. But there isn’t any larger meaning nor a clue of when the next big earthquake will come or where it will hit, she said.

“There’s a human need for creating patterns,” Jones said. “It doesn’t make us safer or less safe. It’s a reminder of our reality.”

Earthquake activity in the Channel Islands shouldn’t be all that surprising. After all, earthquakes created the Channel Islands.

In fact, mountains throughout California are generally creations of earthquakes, Jones said.

Earthquakes pushed up the Santa Ynez Mountains in Santa Barbara and Ventura counties. The Santa Monica and Hollywood faults were responsible for creating the Santa Monica Mountains. The Sierra Madre fault is pushing up the San Gabriels. The Chino Hills were thrust upward by the Chino Hills fault.

“If you see mountains in California, that means something is moving up those mountains faster than erosion is wearing them down,” Jones said in an interview. “Basically, when you see mountains, think earthquakes in California.”

Staff writer James Queally contributed to this report.

joseph.serna@latimes.com

Twitter: @JosephSerna

ron.lin@latimes.com

Twitter: @ronlin

UPDATES:

12:05 p.m., April 6: This article was updated to include another recent earthquake widely felt in L.A. in recent years, the magnitude 5.1 earthquake centered in La Habra.

6:10 p.m.: This article was updated with additional information about the early-warning system and seismic history.

3:50 p.m.: This article was updated with reports of a damaged chimney on a historic property near the quake epicenter.

3:15 p.m.: This article was updated with details on a bald eagle nest on Santa Cruz Island.

2:20 p.m.: This article was updated with reports that there was no damage in Los Angeles.

1:45 p.m.: This article was updated with comments from seismologists and the Los Angeles Fire Department.

1:05 p.m.: This article was updated with comments from John Vidale, director of the Southern California Earthquake Center, and information on past Southern California earthquakes.

12:50 p.m.: This article was updated with a comment from the Los Angeles Police Department.

12:40 p.m.: This article was updated with an upgrade to the quake’s magnitude and comments from the Ventura County Sheriff’s Office.

This article was originally published at 12:35 p.m. on April 5, 2018. </s> Sign up for one of our email newsletters.

LOS ANGELES — Southern California was rattled Thursday by a magnitude 5.3 earthquake that struck near the Channel Islands.

The quake was the strongest in Southern California in several years, jangling some nerves but causing no major damage because it occurred offshore in the Pacific Ocean and not on land.

The quake did cause minor landslides and earth movement on Santa Cruz Island, which was close to the epicenter, and rattled the nerves of a bald eagle whose livestreamed reaction to the temblor went viral.

“A 5.3 could be damaging if it was right under our feet,” said John Vidale, director of the Southern California Earthquake Center at the University of Southern California. “It's right on the edge of being an earthquake that could be dangerous. It's a reminder that we need to be ready in the future.”

The temblor occurred just before 12:30 p.m. and was centered south of Santa Cruz Island. It was felt as far away as Bakersfield, Palmdale and the city of Orange, according to witnesses and the U.S. Geological Survey.

The L.A. area feels an earthquake of this magnitude on average about once a year, Vidale said.

There is a 1-in-20 chance that Thursday's quake will lead to a larger one in the next few weeks, he said. But, more than likely, smaller aftershocks that may not even be felt will follow, he said.

The quake was too small and too far away from the coast to trigger any tsunami concerns.

“It would never make a wave that you could see,” Vidale said.

But it was large enough to activate the state's developing earthquake early-warning system.

Vidale said he and colleagues at USC heard beeping 10 to 15 seconds before the quake's shaking reached their campus.

“We all felt it pretty well. It was small and distinct,” he said. “We heard the warning go off, and then we heard the shaking.”

The early-warning system is under development by the USGS and is available only to a limited array of testers, but it is expected that more people will be eligible to test the system later this year.

It works on a simple principle: The shaking from an earthquake travels at the speed of sound through rock — which is slower than the speed of today's communications systems.

For example, it would take more than a minute for a magnitude 7.8 earthquake that starts at the Salton Sea and travels up the state's longest fault, the San Andreas, to shake Los Angeles, 150 miles away. An early-warning system would give L.A. residents crucial seconds, and perhaps even more than a minute, to prepare.

It got a significant boost in the federal budget signed into law in March, defying an earlier proposal by President Trump to end federal funding for the program.

As part of the $1.3-trillion budget bill approved by Congress and signed by Trump, officials approved $22.9 million for the project. That more than doubles the $10.2 million it got in the previous year's budget.

The USGS has said it planned to begin issuing limited public alerts from the system by the end of this year, as long as funding wasn't cut. Southern California is one area where the network of seismic sensors is dense enough at present to begin early warnings.

The temblor was located near the East Santa Cruz Basin fault zone, said California Institute of Technology seismologist Egill Hauksson, and seismologist Lucy Jones said on Twitter that the fault system “moves Southern California around a bend of the San Andreas fault.”

“Earthquakes happen out there now and again. There's a major offshore fault system,” Hauksson said.

When asked why some people felt the earthquake but others nearby didn't, Hauksson said where a person is matters a lot. “People in high rises probably felt it pretty well,” he said. People on softer soils might also feel stronger shaking.

The epicenter of Thursday's quake was south of the Channel Islands. A magnitude 4.8 quake in the same area rattled the region in 2013, but that epicenter was much closer to the coast, three miles away from Isla Vista, and produced moderate shaking, enough to knock down a few photo frames.

A park service spokeswoman told KEYT that Thursday's quake sent some bricks toppling off a chimney from a historic ranch property built in the 1860s on one of the islands.

The Santa Barbara area is home to a number of earthquake faults, the largest of which is the Santa Ynez fault, which is 80 miles long and runs just north of the city. That fault is believed to be capable of triggering an earthquake as powerful as magnitude 7.5.

The great Santa Barbara quake of 1925, recorded at a magnitude 6.8, destroyed much of the city's downtown on State Street, damaged rail lines, caused extensive landslides and was felt as far away as Orange County. It killed 13 people.

Since the Easter Sunday earthquake of 2010 that hit along the California-Mexico border, there have been 14 earthquakes of magnitude 5 or greater in Southern California. Hauksson estimated that perhaps about half of them were felt in Los Angeles.

Seismologist Jones said she received a complaint Thursday about her calling earthquake activity like this normal. Some people on Twitter asked her what the larger meaning was behind the earthquake. But there isn't any larger meaning nor a clue of when the next big earthquake will come or where it will hit, she said.

“There's a human need for creating patterns,” Jones said. “It doesn't make us safer or less safe. It's a reminder of our reality.”
A magnitude 7.1 earthquake hits Southern California just a day after a magnitude 6.4 earthquake in the same area.