An earthquake measuring 6.1 on the Richter scale hit the Eastern Sierra region at 7:42 a.m. Monday, knocking 53 mobile homes from their foundations in Chalfant Valley, shattering plate-glass windows in downtown Bishop and briefly trapping 300 campers at the Pleasant Valley Reservoir northwest of here.
Only two minor injuries were reported in California's fourth, and strongest, temblor in the past two weeks. Both injuries occurred in Chalfant Valley, a hamlet of 325 residents 11 miles north of Bishop.
A hillside gave way underneath the main access road into the Pleasant Valley campground seven miles outside Bishop, creating a 30-foot-deep hole and damaging a pickup truck without hurting its occupants. Later in the morning, after clearing away boulders, the authorities evacuated the campers by a secondary road.
Power Plants Knocked Out
Fissures, cracks and landslides were reported in other localities. A Sierra Club trail-construction party was briefly stranded by a rock slide that blocked an access road near Pine Lake, 20 miles west of Bishop.
The chief engineer for the Los Angeles Department of Water and Power in the Owens Valley, Duane Buchholz, said three of the agency's power plants, producing a total of 110 megawatts of electricity, were knocked out of service in the Owens River gorge between Bishop and Mammoth Lakes. There was no interruption of power in Los Angeles from the damage.
Seismologists said the quake was on the Owens Valley Fault and was followed by numerous aftershocks, including a 5.2 and a 5.1. The epicenter was 15 miles north of Bishop, between the communities of Chalfant Valley and Hammil Valley, in the same vicinity rattled by a 5.5 temblor Sunday. There had been a number of quakes in the area since July 3, including three magnitude 3 quakes Friday.
Monday's quake was felt over most of California, and in Nevada and Utah as well. Reports of swaying buildings came from as far north as Chico, as far south as Los Angeles and as far east as Salt Lake City. The U.S. Geological Survey in Menlo Park, Calif., said the quake was only about four miles below the earth's surface, which is why it was felt over such a widespread area.
Caltech measured the quake at 6.2 on the Richter scale; the University of California, Berkeley, at 6.1, and the National Earthquake Information Center in Golden, Colo., at 6.0. Such variances are not uncommon when earthquakes are measured from different points and distances.
Seismologists said the Chalfant Valley quake was apparently unrelated to a 5.9 temblor centered near Palm Springs on July 8 and a 5.3 quake off the coast near Oceanside on July 13. A 4.0 aftershock of the Oceanside quake was registered Monday morning, hours after the quake near Bishop.
Altogether, this month has seen the most destructive seismic activity in the state since the May 2, 1983, earthquake that caused widespread damage in Coalinga in the San Joaquin Valley.
The Coalinga quake was a 6.7-magnitude temblor. Each increase of one number on the Richter scale represents a tenfold increase in ground motion.
Although there was no immediate estimate of total damage Monday, the worst destruction was in Chalfant Valley, where, in addition to the 53 mobile homes knocked off their foundations, at least two homes were reported destroyed and almost all of the 145 structures in the community were damaged to some degree.
The town's water supply was disrupted when some pipes burst, and authorities warned residents not to drink the water until silt tests were made. With sewer lines broken, portable latrines were installed.
Victor Benchetler, a building supplier in Chalfant Valley, said he and his wife, Kathy, were asleep when "all of a sudden the whole house felt like it was going to fall down. . . . We ran into the baby's room and grabbed him. Pictures, everything, were falling off the wall. Two console TVs fell over. . . . A chandelier broke off. . . . I've been in rolling quakes, but this was more shaking side to side rather than rolling."
Two Injuries Reported
Kathy Benchetler suffered a few minor cuts, and Dana Sensibaugh, operator of the Chalfant Valley Mercantile store, was struck by falling debris and slightly hurt. They were the only injuries reported in the quake.
Shirley Burnett said she had to claw her way out of her mobile home with a hammer, after the walls collapsed and the structure fell two feet from its foundations, blocking both doors.
Burnett said she was cleaning up the damage in her home from the previous day's quake, when the bigger one hit. She said her first thought was, "Oh my God, there's going to be another mess in my house." A moment later, her only thought was leaving.
"At first, it was a kind of a slow rolling and suddenly it hit hard, and then I said to myself, 'Man, I just better get out of here,' " she said.
Burnett's home appeared to be a total loss.
Becky Manross returned home from her job in Bishop to find a six-foot-deep hole where her previously level front yard had been.
Her next-door neighbor, Nora Denmark, marveled that before the quake, the door to her home was locked and dead-bolted, but during the quake "it swung right open." When Denmark and her husband looked around, they found that their mobile home had moved two feet from its original place.
Most of the merchandise fell from the shelves at the mercantile store. Among those arriving to help Sensibaugh restore order was the manager of a supermarket in Mammoth Lakes, who drove 55 miles to offer his assistance, and 16 boys from a Probation Department camp in neighboring Mono County.
In the afternoon, Chalfant Valley still had no electric power, no safe running water, no working sewers and the authorities had ordered the gas turned off. A sign in the fire station warned residents against drinking contaminated liquids.
In neighboring Hammil Valley, horse trainer Pat Bartlett said that his father-in-law was on the telephone from Pasadena inquiring about Sunday's quake, when Monday's occurred.
"What we didn't lose yesterday, we lost it today," Bartlett said. "The TV's hanging off the stand. A trailer outside was knocked off its foundation. . . . The ranch right next door to us has serious cracks in the walls, inside and out."
Bartlett said that in Sunday's temblor, his 15 horses did not seem particularly bothered.
"Today, they were all trying to get out of their pens," he said. "They were very excited."
In downtown Bishop, there was structural damage at the First Sierra Bank building, where part of the front brick facade fell onto the sidewalk, and at a Burger King restaurant, where part of the ceiling collapsed. Plate-glass windows were shattered at a number of businesses.
The manager of the Rexall drug store, Chuck Dugas, said a showcase was smashed at his store, and the manager of the Bank of America branch, Tom Ferrara, reported that ceiling panels fell and furniture in the lobby was overturned.
Power was knocked out for more than an hour in some parts of Bishop. The city, with a population of 3,550, is the largest urban center in the Eastern Sierra.
Summer is a time when thousands of campers and vacationers flock to the mountains around Bishop, and there were reports Monday that quite a few had been at least temporarily stranded by rock slides that blocked some of the roads into camping areas.
The worst disruption, however, was at Pleasant Valley Reservoir, with 200 camp sites and recreational vehicle places. A 150-foot section of the access road dropped about 30 feet. At the time, there was a camper-pickup truck with six occupants entering the area. The camper, driven by Art Lucero of Canoga Park, fell into the hole and caught fire.
Lucero was quoted by others as saying, "The road rose up about 10 feet in front of us, and then the whole road collapsed, and we went down with it."
Along with Lucero in the camper were his father and 6-year-old son, both also named Arthur Lucero, said Lucero's wife, Sandy, who did not make the trip. Also in the vehicle were Lucero's nephews, Michael Ricketts, 6, of Oxnard and Brandon Lucero, 2, and a family friend Sandy Lucero knows only as Luis.
Lucero and his party escaped without injury.
"They were lucky, lucky, lucky," Sandy Lucero said Monday evening from her Canoga Park home.
She said she had spoken to her husband by phone, and he said he was driving along the road when he suddenly felt the quake.
He tried to slow down and stop, she said, when suddenly he saw the ground open up in front of him.
"The ground gave way, and the camper slid down, landing on its side," she said her husband told her. "All of a sudden he was looking up at the road above his head."
Lucero had just filled the camper's gasoline tank and a propane tank in the camper, she said. A small fire broke out, but he was able to quickly put it out with a fire extinguisher, she said.
One lane of U.S. 395 was briefly blocked by a rock slide on the Sherwin Grade leading to Mammoth Lakes northwest of Bishop.
No appreciable damage was reported at Mammoth Lakes, but the nearby Hot Creek bathing area was ordered temporarily closed after more fissures and increased hot spring activity was noted.
"We don't know the temperature of the water, but we felt it was safer to close it," said Bureau of Land Management spokesman Brian Miller.
In downtown Los Angeles, 265 miles south of Bishop by road, tax lawyer Ernie Schmider, at work early in his office on the 44th floor of the Bank of America Tower, felt the quake distinctly.
"There was a little bit of a shake and the doors began swaying and there was a creaking of window frames," Schmider said later. "It was enough for me to go find a door to stand in."
As a routine precaution, Los Angeles firefighters placed themselves and their equipment outside of station houses for about an hour.
Monday's quake occurred about 25 miles southeast of the Mammoth Lakes area and the Long Valley caldera, where authorities had given notice of possible volcanic activity after a spate of earthquakes in 1980.
However, David Hill, in charge of the U.S. Geological Survey's monitoring of the seismic and volcanic situation in the area from a Geological Survey outpost in Menlo Park, said the latest temblors apparently have nothing to do with volcanic activity.
"These earthquakes are located . . . east of the Long Valley caldera," Hill said. "They are probably associated with the fault system on the west side of the White Mountains (north and east of Bishop). So we suspect that these earthquakes are involved with that system.
"We have no evidence so far that they are associated with the Long Valley caldera. . . . We're continuing to monitor that system very closely, but we haven't seen any significant earthquake activity within the caldera."
George Ramos reported from Bishop and Kenneth Reich from Los Angeles.