It was 25 years today, on Jan. 17, 1994, when a ferocious 6.7 earthquake hit Northridge at 4:30 in the morning.
Buildings, homes and even portions of the Golden State Freeway collapsed, 57 people were killed and caused as much as $44 billion in damage.
Not only the earthquake itself, but subsequent aftershocks caused extensive damage.
The epicenter of the Northridge quake was at Wilbur and Arminta, only one mile from the CSUN campus.
At the Northridge Meadows Apartment, a short walking distance from CSUN, the upper floor collapsed onto the floor below, its carport crumbling and destroying parked cars. Residents had no warning as the apartment building gave way.
Today, local and state officials, including LA Mayor Eric Garcetti, returned to CSUN with earthquake expert Dr. Lucy Jones to discuss this crucial topic.
Earthquake experts at USC also recently gathered to discuss what has been learned 25 years later.
“The damage to steel frame buildings was a big shock to engineers after the Northridge earthquake,” said Gregg Brandow, USC professor of engineering. Brandow is also a licensed civil and structural engineer.
“We thought steel frame buildings, including high-rises, were ductile, but they proved brittle. Many are vulnerable, especially if we get a big quake on a big fault because it will shake much longer than Northridge did and damage will be greater,” Brandow said.
While local ordinances have led to retrofits for some classes of buildings, this hasn’t been the case across the board, even for old concete buildings. “We are just starting to retrofit some of these buildings across LA,” he said.
New high-rise building construction has improved since Northridge, said Brandow, but welds in older steel frame buildings remain a concern.
“The Northridge quake occurred on an unknown fault, so we’ve learned there’s a lot more faults in Southern California. Today, we assume a 6.5 quake could occur anywhere and we account for this in the hazard assessment,” said Christine Goulet, executive science director for Special Projects at USC.
The LA basin is a sediment-filled rock bowl and violent shaking affects soft soils. “If you can more accurately predict how the ground will shake, you can design structures better,” said Goulet, who pointed out what happened in Northridge revealed poorly constructed buildings.
“Since the Northridge quake, we’ve been doing most of the right things, such as fixing weaknesses in old buildings. But we need more improvements in the building code, hazard maps and faster early warning systems. Quakes beget nearby quakes, which load stress onto adjoining faults which is a key to building better hazard maps,” said John Vidale, USC Professor of Earth Sciences.
Most recently, the announcement of the new app ShakeAlertLA could give residents as much as a 30 seconds or even possibly as much as a minute warning, but Vidale said more is needed that include faster phone systems to become truly effective.
Those living in the San Fernando Valley and Greater Los Angeles have always been warned by seismologists to expect the “Big One” and prepare. But despite the reminders, still too few people actually do prepare and most become complacent — although there is so much that residents can do.
Experts continue to stress the need for being prepared across the board. Preparation for impending earthquakes can save lives.
“Bolt older homes to foundations and anchor chimneys. Preparation pays. Store water and food and make plans to adapt to the potential loss of utilities and shelter,” urged Brandow.