LOS ANGELES (CNS) - It was 20 years ago today that Southern Californians were jolted out of their sleep by the magnitude-6.7 Northridge Earthquake, and several events will be held to look back on the devastation, celebrate quake-technology advances in the years since and urge residents to be prepared for the next large temblor.

After the dust settled from the Northridge earthquake on Jan. 17, 1994, at least 57 people were dead -- some put the death toll at 61 -- and 11,846 people in Los Angeles, Orange and Ventura counties were treated at hospitals.

Property losses were pegged at $40 billion.

It was the costliest disaster in U.S. history. Insured losses were estimated at $12.5 billion. Aid from the federal government was estimated at $13 billion.

In Los Angeles, Orange and Ventura counties, a total of 114,039 residential and commercial structures were damaged. But only 9,001 of those were in Ventura County, and just 19 were in Orange County, according to local business departments.

The quake, which struck at five seconds before 4:31 a.m., affected an area covering 2,192 square miles. It was the first temblor to knock out power in every area of the vast metropolis of Los Angeles. The floor of the San Fernando Valley was completely blacked out after the shaking stopped, except for a few fires visible for miles.

City Councilman Mitchell Englander will take part in an early morning ceremony at Northridge Recreation Center today to mark the quake's anniversary.

The Valley Economic Alliance will hold a daylong event at Cal State Northridge, beginning with exhibit booths on the university campus and followed by a series of public quake-related workshops presented by the California Small Business Center, Department of Water and Power, Los Angeles Fire Department, Microsoft and Valley Economic Development Center.

At midday, a luncheon will be held to honor people who played a critical role in the area's recovery effort, including former Councilman Hal Bernson, former Mayor Richard Riordan and then-Gov. Pete Wilson.

Mayor Eric Garcetti is among the dignitaries expected to take part in the luncheon. Earlier this week, in recognition of the quake's anniversary, Garcetti announced a partnership with well-known seismologist Lucy Jones aimed at ensuring the city is prepared for the next large shaker.

``The truth is, while Northridge was a bad earthquake, the big one could be a lot worse,'' Garcetti said. ``We've gone 20 years here in Los Angeles since the last big earthquake, and because we haven't had a recent reminder of the power and the damage of earthquakes, too many in our city have stopped thinking about how we can best prepare.''

Jones, a familiar figure and go-to expert with the U.S. Geological Survey, has been a visiting researcher at Caltech's Seismological Laboratory since 1983.

Other advances in earthquake science since 1994 include the expansion of the Southland's seismic network, which records, measures and detects quake activity.

The region contains numerous active faults, ``and in the future we'll have large earthquakes in them,'' according to Thomas Jordan, director of the Southern California Earthquake Center. He added that scientists have been able to map previously unknown potential problem areas.

The Northridge fault -- an offshoot of the San Andreas fault -- previously was unknown to seismologists, Jordan said.

Jones described the pre-Internet era as a kind of technological Stone Age in which scientists could not download information from computers tracking the Northridge quake for two hours because the machines were so busy taking in data. Today, it takes minutes to download real-time data.

``It's a big contrast,'' she said.