2 Strong Quakes Jolt Wide Area : 7.4 Desert Temblor Is Sharpest in 40 Years : Tremors: The shock near Yucca Valley is followed by a 6.5 jolt at Big Bear Lake. A child is killed and at least 350 people are injured. Rockslides block highways and a power blackout affects 550,000 in the region.

YUCCA VALLEY, Calif. —  Two strong earthquakes and dozens of powerful aftershocks shook Southern California awake Sunday, causing one death and at least 350 injuries in the desert and inland mountains but mostly sparing the urban sprawl from damage.

The violent temblors, which jostled skyscrapers as far away as Denver, ruptured the ground for 44 miles and buckled roadways in the high desert north of here. Residents in remote towns were left without water, and rockslides that blocked highways stranded vacationers for a time in the Big Bear and Lake Arrowhead areas.

Power blackouts affected more than 550,000 people around the region, and downed power lines sparked about two dozen fires. Shaken victims crowded hospital emergency rooms, and more than 650 people--some homeless, others just jittery--were expected to spend Sunday night in emergency shelters or camping out in parks in rural San Bernardino County, authorities said.

Officials said 10 homes were destroyed and 1,111 damaged in San Bernardino County. Another 10 businesses were destroyed and 33 damaged. Property loss was estimated at $16.3 million.

The first shaker struck at 4:58 a.m. in a desolate area six miles north of Yucca Valley, a small desert community nestled along California 62 outside Joshua Tree National Monument. Rousing Sunday morning sleepers from northern Mexico to San Luis Obispo, the magnitude 7.4 quake was the strongest in California in 40 years and almost three times the strength of the destructive Bay Area earthquake of 1989.

Three hours later, a magnitude 6.5 temblor centered east of Big Bear Lake unleashed a new round of tremors, causing slides that temporarily trapped 100 motorists and shrouded the San Bernardino Mountains in a massive dust cloud. Seismologists said it was on a different fault but may have been triggered by the earlier quake.

“It was like someone picked me up out of bed and threw me on the floor,” said Cindy Ness of Yucca Valley. “Every time I tried to get up it threw me back down again. Everything in the room was crashing down around me.”

“I thought paratroopers were landing on my roof,” said Jay Connor, who rode out the jolts at his cabin near Lake Arrowhead.

As strong aftershocks continued through the day and into Sunday night, the state Office of Emergency Services highlighted the seriousness of the twin quakes by issuing an unprecedented advisory urging people to stay off freeways and curtail activity. Scientists called the event a “major earthquake sequence” and state authorities asked local governments to remain on alert.

Later in the day, state officials rescinded the warning about freeway travel, but joined with scientists in warning of a 50% chance that another quake reaching magnitude 6 or greater could hit the area this week.

After surveying the stricken region by helicopter, Gov. Pete Wilson declared a state of emergency in the counties of Riverside and San Bernardino. The declaration allows cities and counties to apply for state funds to make repairs.

Asked whether the state budget crisis will hamper the availability of funds, Wilson said: “We’ll provide the help first and worry about that later.”

Although major damage and injuries were confined to the isolated desert and mountain towns near the epicenters, the temblors were the news du jour across Southern California on Sunday. Some people stayed glued to their televisions for the continuing broadcasts, while others toted radios to the beach to stay abreast of the story.

Everybody had a tale to tell, especially the region’s shaken tourists--300 of whom were evacuated from the Disneyland Hotel in Anaheim.

“It was like being on top of a mast in a sailboat,” said Gerry Zemojtel, 38, of Tacoma, Wash., one of the evacuees. “When I went to grab my baby out of the crib, I reached in and he rolled by and I missed him.”

The morning’s first quake landed its toughest punch on the string of rustic towns that straddle California 62 east of Palm Springs--Morongo Valley, Yucca Valley and Joshua Tree, all of which suffered damage just two months ago when a magnitude 6.1 quake struck.

In Sunday’s shaking, the wall of a bowling alley and the roof of a K mart in Yucca Valley collapsed, mobile homes were tossed off their foundations, water mains were snapped and four dwellings were destroyed or badly damaged by fires. The town’s main supermarket and numerous other businesses closed because of damage and toppled goods.

The lone fatality directly linked to the quake occurred in Yucca Valley when a 3 1/2-year-old boy was crushed by falling masonry. The toddler, Joseph Bishop, was asleep near a living room chimney when it fell on him, authorities said.

“We lost a member of our family, a loved one,” said the child’s father, who declined to give his name or discuss the circumstances surrounding the boy’s death.

Acquaintances said the child’s parents, who live in Newbury Port, Mass., were visiting their hometown and staying with friends while attending a 20th reunion at Yucca Valley High School.

Hi-Desert Medical Center in nearby Joshua Tree treated more than 100 people for minor injuries, most of them cuts and sprains. Twelve people were hospitalized.

Desert residents described the quake as a long, terrifying ride that was dramatically stronger and sharper than the temblor they experienced on April 23.

Sipping coffee on her front lawn Sunday morning, an edgy Edie McDowell said her house “shook like mad--back and forth and back and forth, incredible contortions.” The force of the quake uprooted a toilet in her son’s home and toppled his fish tanks.

“I am scared to death,” McDowell said. “I’ll bet you see the for sale signs go up all over this place tomorrow.”

North of the epicenter, the desert hamlets of Landers and Flamingo Heights weathered some of the worst rattling--and had some of the most dramatic evidence to prove it. The main highway that passes near town, California 247, suffered deep craters and three-foot-wide cracks, forcing passers-by to detour onto the desert. On one side street, the pavement sank five feet and became a collection of gaping fissures.

The earth’s gyrations also etched long furrows in the desert sand, yanked porches off of homes and businesses and shifted chain-link fences.

Susie and Pedro Gonzales were so unnerved that they moved their living room furniture into the front yard. They set up a barbecue and tent and made plans to camp out for at least one night.

“The kids were so scared we decided to move outside,” said Susie Gonzales, whose eight grandchildren were visiting.

As the dust settled, the biggest problem confronting the high desert was water. More than 5,200 people were without water because of broken mains and other system damage, and some stores limited customers to one jug per person. San Bernardino County Supervisor Barbara Riordan said the National Guard might be asked to bring water in by truck.

In Landers, tremors ruptured the towns’ 250,000 gallon water tank and snapped numerous distribution pipes, leaving 1,200 residents scouring for supplies as the desert sun drove the temperature over 100.

Fred Nokes, 57, stopped by the tiny Landers post office in hopes of finding some water, but struck out: “I guess I’ll have to drain my water heater,” Nokes said glumly as he climbed back in his battered pickup truck.

Sunday’s second earthquake, which struck at 8:04 a.m., heaped its wrath on the mountain resorts near Big Bear Lake. A popular tourist attraction, the picturesque region was hosting about 100,000 visitors Sunday--including 3,000 vacationers attending the Big Bear Scottish Festival and Games, which was canceled.

“The party’s over,” lamented Big Bear City Councilman Bill Dwyer. “We must have had half a dozen major events going on up here and every single one has been disrupted.”

City-owned buildings were unscathed, Dwyer said, but at least four commercial structures suffered major damage. In addition, the Community Market near the lake’s east end burned to the ground and entire blocks of buildings along the lake’s main boulevard were damaged when their brick or stone chimneys pulled loose and crumbled.

Fifty-eight people sought treatment at Bear Valley Community Hospital, and the injuries quickly overwhelmed the 28-bed facility, said chief executive officer Jon D. Smiley.

Patty Reynen, who came for treatment of a twisted ankle, said she was in the office of the 200-unit condominium complex she manages at the Snow Summit ski resort when the second quake hit.

“My husband was just saying to calm down--that it’s all right now,” Reynen said. “Then it started shaking again. I was just going down the staircase and I got pitched out the door. I landed face first.”

At Big Bear City Park, 200 people unable or unwilling to sleep in their homes Sunday night set up a temporary encampment--raising tents, creating make-shift canopies out of blankets and stocking up on food, barbecues, ice coolers and clothing.

One of the campers, Heidi Miller, said her home is a shambles and believes that the cracked chimney will tumble if another strong jolt strikes.

“Everything was demolished,” Miller said of her Big Bear City house. “This family got out and is going to stay out.”

At the 75-room Big Bear Inn, the temblor interrupted a Rossini Music Festival and forced the evacuation of 25 guests.

Shortly after the Earth shifted for the first time Sunday, vacationing “flatlanders” began a hasty exodus from the mountains. The fleeing vacationers jammed the main street through the lakeside city and were joined by some year-round residents--whose uneasiness about additional tremors prompted them to pack up and get out.

Initially, however, tourists and refugees alike found all roads leading from Big Bear either partially or completely shut down--blocked by rockslides. In the hours immediately after the quakes, California Highway Patrol officers escorted travelers around the pavement bulges and mounds of rubble, but the going was slow and precarious.

All the roads have reopened except for California 38 south from the Big Bear area, which is likely to remain closed for several days.

In one odd road scene, hundreds of Corvettes were snaking down California 18--a back exit into Lucerne Valley--cutting short a weekend convention of classic Corvette owners.

There were a few lighter moments in the mountains Sunday. Teacher Beth Little and librarian Michael Ranson held their wedding as planned at a romantic lakeside lodge amid the evergreens. One-third of the guests could not reach the fete because of road closures, but Little found a silver lining.

“It took away a lot of the stress of the wedding,” she said, “because the quake was such a big thing.”

Elsewhere in Southern California, there were scattered injuries as well as power outages and reports of small fires and other damage.

Airports throughout the region continued to operate normally, but Amtrak canceled seven trains on the 233-mile route from San Diego to Santa Barbara, filling in the missing service with buses. No track damage was immediately found, and service was expected to return to normal today.

In Los Angeles, more than 51,000 people lacked power at one point Sunday, and officials said 15,000 could still be without electricity this morning.

Unperturbed, the Dodgers took the field as scheduled against the Houston Astros, and hundreds of Amnesty International members in town for the human rights group’s national meeting continued their work--but moved their sessions outside among the homeless in Pershing Square after the Biltmore Hotel suffered superficial damage.

In San Diego, about 1,000 guests were evacuated from the 18-story Hyatt Islandia hotel on Mission Bay after water pipes ruptured. Clad in bathrobes and pajamas, guests milled about and ate breakfast in a parking lot for about three hours before they were told they could return to their rooms.

At the Crystal Cathedral in Garden Grove, about 100 fleeing parishioners watched in horror as the seams at the corners of the towering steel-and-glass structure separated and then snapped back together with the force of the rolling. The church, known for its 10,000 panes of glass, was not damaged.

Sunday’s 7.4 quake was the strongest to strike California since the Tehachapi quake of July 21, 1952, in Kern County. That temblor, a magnitude 7.7, killed 12 people and injured 18. The most powerful earthquake in recorded history in California remains the devastating 1906 earthquake in San Francisco, which seismologists later determined to be a magnitude 8.3

Double Shaker

Here are some key facts about the earthquakes: * The quakes: At 4:58 a.m, a magnitude 7.4 temblor in Landers. At 8:04 a.m., a second quake of magnitude 6.5 in Big Bear.

* The strength: Landers quake is the strongest to hit the state in 40 years; the last one stronger was a 7.7 temblor in Kern County in 1952.

* The toll: 1 fatality confirmed, and hundreds injured.

* The damage: Estimate for San Bernardino County: $16.3 million

* The range: Skyscrapers reportedly swayed in Denver, Colo. and water in swimming pools sloshed over in Boise, Ida. Also felt in Salt Lake City, Utah.

* Twin temblors: Rarely do two major earthquakes strike along different fault lines in a single area within hours of one another. After Sunday’s twin quakes, seismologists said the chance of a magnitude 6 or greater aftershock within a week is about 50%.

* The warning: State emergency officials on Sunday advised Southland residents “to curtail nonessential activity and to the extent possible stay off the freeway system” for the day.

Earthquakes’ Effects

Sunday’s two powerful earthquakes, measuring magnitudes 7.4 and 6.5, buckled highways, caused fires and power outages, and ruptured water systems. The most serious damage appeared to be near the two quakes’ epicenters, located in the desert town of Landers and the mountain community of Big Bear. Below are some of the earthquakes’ effects in some of the harder hit areas. A. In Yucca Valley, Joseph Bishop, 3 1/2, is killed by falling cinder-block from a chimney. A bowling alley collapses and a K mart store is also badly damaged.

B. The main road into the desert community of Landers, California 247, suffers a 30-foot-long, foot-deep crack. There was also an eight-foot-deep crater.

C. About 100 people from 50 cars are temporarily stranded on California 38 near Angelus Oaks because of rockslides.

D. More than 110 people are treated for injuries at the Hi-Desert Medical Center in Joshua Tree.

E. About 30 injured are treated at Desert Hospital in Palm Springs.

F. All roads in and out of Big Bear are temporarily closed. Fires damage or destroy three buildings, and another seven collapse. More than 58 earthquake-related injuries are reported at Big Bear Valley Community Hospital, including two heart attacks.

Big Quakes

In the last 20 years, California has had 20 earthquakes of at least magnitude 6.0.

Location Date Magnitude Pacific Ocean Nov. 8, 1980 6.6 Ferndale Nov. 26, 1976 6.0 Petrolia April 25, 1992 7.1 Pacific Ocean Aptil 26, 1992 6.7 and 6.6 Oroville Aug. 1, 1975 6.1 Morgan Hill April 24, 1986 6.2 Mammoth Lakes May 25, 1980 6.3 and 6.0 Mammoth Lakes May 27, 1980 6.0 Chalfant Valley July 21, 1986 6.1 Loma Prieta Oct. 17, 1989 7.1 Coalinga May 2, 1983 6.5 Avenal Aug. 4, 1985 6.0 Desert Hot Springs April 22, 1992 6.1 Westmoreland Nov. 23, 1987 6.2 Westmoreland Nov. 24, 1987 6.6 Calexico Oct. 15, 1979 6.6 Big Bear June 28, 1992 6.5 Landers June 28, 1992 7.4