Why we rolled with the punch

The earthquake that rattled Southern California on Tuesday might have caused devastation if it had taken place in some parts of the world, but relatively strict building codes ensured that most of the region’s infrastructure -- homes, schools, freeways and rail systems -- rolled with the magnitude 5.4 punch, which was centered near Chino Hills and felt as far away as Las Vegas.

As aftershocks continued to reverberate, officials inspected airports, freeways and buildings and reported little damage from the quake, which occurred at 11:42 a.m. and was the first significant temblor in more than a decade to be centered in an urban area of California. The biggest strains were felt in phone and Internet systems, which buckled because of overwhelming demand in the minutes after the jolt.

The quake struck hardest in an area of San Bernardino County that has seen massive growth in population and housing in the last decade. That meant that the buildings shaken the hardest were mostly built under California’s strictest building codes, updated in 1997 in response to the 6.7 Northridge quake of 1994. That kept damage to a minimum.

Only minor injuries were reported, three at an outpatient medical clinic in Brea and five at a building in the Wilshire district of Los Angeles.

“The most interesting thing to us is that this is the first one we’ve had in a populated area for a long time,” seismologist Kate Hutton of Caltech said. “People have forgotten what an earthquake feels like. We should look at this as an earthquake drill for the Big One that will come one day.”

Although moderate in intensity, the quake rumbled up from a relatively shallow depth, making it feel sharper, stronger and scarier than its magnitude suggested, especially in areas close to the epicenter.

“It’s the first time in my life I actually got under my desk,” said Anaheim Police Sgt. Ken Seymour, a native Southern Californian.

Robert Heded, 32, a Time Warner technician who lives in Culver City, was about 30 feet up a telephone pole at La Cienega and Pico boulevards in Los Angeles when the quake hit.

“I just sat there and waited, kinda rode it out,” he said a while later as he bought an energy drink at a 7-Eleven, still dressed in his reflective safety vest.

The lines were “swaying a lot more than usual, about four feet from side to side,” he said. “I wasn’t sure what was happening, if it was an earthquake or if it was me.” Heded said he finished up his work, still strapped to the pole in his safety gear. Then made his way down.

“It was bad,” said Nirmala Dawson, the director of the Montessori School of Chino. She said the school performs frequent earthquake drills. “But at that moment, to be honest, we forgot them. We just evacuated.”

No one was injured, she said, but a few children were frightened by the shaking. Then, after the quake, phones began ringing off the hook with calls from parents.

That nearly universal instinct to call loved ones -- or someone -- strained the capacity of the regional phone network, perhaps instructive for officials planning emergency responses to the next massive earthquake.

Verizon lost some phone service Tuesday in several quake-affected areas. “We have some outages on our land-line side,” said Jonathan Davies, Verizon spokesman. “We’re not sure yet if it’s physical damage or just due to high call volumes.”

AT&T;’s cellphone service was spotty in some areas. Sitting in a Starbucks in Pasadena, Paul Roberts was able to get calls on his cellphone. “But I am sitting here with my buddy, who has AT&T;, too, and he can’t make outgoing calls,” said Roberts, a student at Art Center College of Design.

The Los Angeles Times’ website, latimes.com, was briefly unavailable to many users when heavy traffic swamped its servers immediately after the earthquake. Full access returned in about 10 minutes, according to Meredith Artley, the executive editor of the site. It had about 630,000 page views in the hour after the temblor, roughly double the usual amount.

The earthquake slowed, but for the most part didn’t stop, the region’s transportation network.

A section of the southbound Interstate 5 near Bake Parkway in Irvine was briefly closed to traffic so that Caltrans workers could inspect it, according to Tom Marshall, spokesman for the California Highway Patrol. No problems were found.

No disruptions were reported on Los Angeles County highways. Raja Mitwasi, chief deputy director of the Caltrans office in Los Angeles, said Caltrans was inspecting highway bridges and pavement, but had not found any signs of damage.

The biggest delays were on passenger trains, which were slowed to allow inspectors access to tracks.

Denise Tyrrell, a Metrolink representative, said there were delays of about an hour on Metrolink trains serving Orange, Riverside, San Bernardino and Los Angeles counties. Metrolink use is at an all-time high because of rising gas prices. Similar delays were reported on Amtrak’s Surfliner trains, with shorter ones on Los Angeles County’s Metro Rail lines.

On Tuesday afternoon at Union Station in Los Angeles, some passengers affected by the delays said they understood the need to check tracks for damage.

“They had to do what they had to do to make sure it was safe,” said Pete Paladino, 64, a special needs teacher who was delayed about 30 minutes on the Red Line to downtown and was headed home to Upland.

The quake briefly knocked out the ground radar system at Los Angeles International Airport but did not affect any flights, LAX officials said. The radar is linked to a safety system that warns air traffic controllers of potential collisions. Nancy Castles, a representative for the airport, said no damage has been found at LAX except for a broken water heater that caused some flooding in the checked baggage area of Terminal 7.

One terminal at Ontario International Airport sustained cosmetic damage, but flights were not affected, according to spokesman Harold Johnson. Staffers at John Wayne Airport in Santa Ana closed one runway for five minutes after the quake to inspect it, airport spokeswoman Jenny Wedge said. They found no damage.

The quake did cause its share of damage, mostly in the form of shattered glass and dislodged bricks. In Los Angeles, problems included flooding at a Macy’s in Woodland Hills; some people stuck in an elevator at Pershing Square; some cracking and other minor damage to some downtown buildings; and five minor injuries to people in the 3600 block of Wilshire Boulevard “who were rushing and trampling each other out the building,” according to City Councilwoman Wendy Greuel, who was serving as acting mayor in the absence of Mayor Antonio Villaraigosa, who was on vacation in London.

The quake gives new urgency to a drill, the Great Southern California Shakeout, being planned for November by a consortium of public and private organizations. It will simulate the response to a magnitude 7.8 quake on the San Andreas fault.

Seismologists consider such a quake to be inevitable, although they cannot predict when it might hit. To put the latest temblor in perspective: A 7.8 quake would be 3,981 times more powerful than one of magnitude 5.4, according to Anthony Guarino, a seismic analyst at Caltech.

The recent devastating earthquake in China’s Sichuan Province was calibrated at magnitude 7.9. As powerful as that quake was, it also demonstrated what can happen when buildings are not built to the highest earthquake standards. Hutton, the Caltech seismologist, said even a 5.4 quake could cause widespread damage “anyplace where there’s no earthquake regulation, where no reinforcement is required.”

The Chino Hills quake hit hardest in an area of relatively new development. Valerie McClung, community relations manager for the city of Chino Hills, said almost all of the residential and commercial development in the city began no earlier than 1991, the year the city was incorporated.

Most development, she said, occurred after the Northridge quake.

“It’s the best possible location,” said Lucy Jones, chief scientist for the Multi-Hazards Initiative of the U.S. Geological Survey. “If this had happened in San Bernardino, where there are over 200 unreinforced masonry buildings, we would have had a lot of downed buildings.”

Jones said big earthquakes often lead to an upgrade in building codes.

For instance, she said, unreinforced masonry was outlawed in California in a 1935 code, adopted in the aftermath of the 1933 Long Beach earthquake.

The 1997 code, adopted after Northridge, banned brittle steel and mandated that builders use a stronger welding material to join steel parts.

“Each time there’s a big earthquake, we say ‘Oops, we hadn’t thought about that one before,’ ” Jones said.

It helps when the quake occurs in an urban area. When that happens, said Thomas Heaton, a professor of engineering and seismology at Caltech, “It means 10 million people feel it. If it happened in the Mojave Desert it sure wouldn’t have been as big a deal at all.”

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joel.rubin@latimes.com

david.pierson@latimes.com

mitchell.landsberg@latimes.com

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Web features

More on the Chino Hills earthquake is available on latimes.com:

* Reporters’ dispatches, on the L.A. Now blog.

* How local schools and transportation handled the quake.

* Why cellphone service failed, on the Technology blog.

* Voices of people who live near the epicenter.

* Maps, earthquake resources, photos, video, graphics and historical data.

* Comments from more than 1,000 readers speaking out on the quake.

latimes.com/chinoquake

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The following Times staff writers contributed to the earthquake coverage:

Tami Abdollah, Tony Barboza, Esmeralda Bermudez, Andrew Blankstein, Howard Blume,

Jia-Rui Chong, David Colker, Cara Mia DiMassa, Paloma Esquivel, Jessica Garrison, Anna Gorman, Jeff Gottlieb, Martha Groves, Carla Hall, Molly Hennessy-Fiske, Jill Leovy, David Kelly, Rong-Gong Lin II, Jean Merl, Robert J. Lopez, Seema Mehta, Joe Mozingo, Charles Ornstein, Stuart Pfeifer, Bob Pool, Tony Perry, Paul Pringle, Jean-Paul Renaud, Susannah Rosenblatt, Michael Rothfeld, Ann M. Simmons, Garrett Therolf, My-Thuan Tran, Ruben Vives, Dan Weikel, Phil Willon, Richard Winton, Kimi Yoshino and David Zahniser.