A wide area of Southern California rolled today with another aftershock of Wednesday's big earthquake, triggering a rockslide on a mountain road but no reports of significant damage or injuries. The quake shook Los Angeles, Riverside, San Bernardino and San Diego counties. It also hit Orange County, where President Bush was addressing a noon anti-drug rally. The aftershock measured 4.7 on the Richter scale at 9:26 a.m., said Robert Finn, spokesman for the California Institute of Technology in Pasadena. It was preceded today by a 2.5 quake at 2:52 a.m. and followed within two hours by about 10 quakes under magnitude 2.5, including a 2.4 at 10:41 a.m., according to Caltech. A rockslide closed Mount Baldy Road in the mountains north of Upland and only residents were allowed through, Caltrans spokesman Anthony Hughes said. ``It was scary and I'm shaking. But nothing fell or flew this time,'' said Melina Manning of Ontario, two miles south of the epicenter. ``All the pans and the lights swayed back and forth. It was mild compared to the other day but very scary especially because your nerves are shot from the other day.'' ``I was under the desk again. It was very strong here,'' said state Office of Emergency Services spokesman Michael Guerin in Ontario. The aftershocks came as Southern Californians bounced by the largest quake to hit the region in more than two years were sweeping up after millions of dollars in damage. City council members in Pomona _ hardest hit of several areas struck by Wednesday's earthquake _ said they would meet today to request that Gov. George Deukmejian assist them in obtaining federal or state funds to repair an estimated $10 million in damage in their city. The state Office of Emergency Services said Thursday the quake, measuring 5.5 on the Richter scale, caused at least $12.7 million damage in the cities of Claremont, Pomona, La Verne, Chino, Ontario, Rancho Cucamonga, Montclair and Upland and the counties of Los Angeles, Riverside and San Bernardino. The figure ``is very preliminary, based on information provided by cities and counties,'' said Guerin. The quake, felt along the coast from San Diego to Santa Barbara and as far east as Las Vegas, was centered on an unnamed fault three miles northwest of this city 40 miles east of Los Angeles. It toppled scores of chimneys, shattered hundreds of windows and collapsed one building's wall, but remarkably, caused no major injuries or deaths. Dozens of smaller aftershocks have rattled the area since. There was no official estimate of the number of injured other than ``several dozen'' from the OES. The most serious injuries, officials said, were a few broken bones. Only one person, a Pomona man, was known to have been left homeless by the quake. But the temblor spurred renewed calls for Southern Californians to prepare for the so-called ``Big One,'' a catastrophic earthquake measuring between 7.5 and 8 on the Richter scale of ground motion. A 1988 U.S. Geological Survey report said that a quake that size is at least 60 percent likely by the year 2018 on the southern San Andreas Fault. ``This is the handwriting on the wall and we better start looking at the design of some of our buildings,'' Pomona Vice Mayor Clay Bryant said Thursday. ``We've already been put on notice by a 5.5.'' Pomona Mayor Donna Smith said city inspectors were compiling a list of how many unreinforced masonry buildings remain in the city, which has several landmark structures more than 100 years old. She said 301 buildings in Pomona were damaged and 17 were declared uninhabitable. Pomona, Claremont and La Verne all declared local states of emergency Wednesday, but the La Verne City Council withdrew its declaration Thursday after determining damage was not as bad as first believed. The destruction was widely scattered throughout the region. In Pomona, for example, part of the south face of the 58-year-old brick-and-concrete Trinity United Methodist Church collapsed while the brick Pilgram Congregational Church a block away withstood the quake. At the city's historic Phillips Mansion, built in 1875, a chimney toppled onto a roof, causing an estimated $500,000 damage, but surrounding buildings were unscathed. Despite the damage, the quake was far less serious than the one that struck the Whittier area on Oct. 1, 1987. That one measured 5.9 and, together with a 5.3-magnitude aftershock on Oct. 4, killed eight people, injured more than 200 and caused $358 million in damage. The Richter scale is a measure of ground motion as recorded on seismographs. An earthquake of 5 can cause considerable damage and 6 severe damage.