The seismic tremors that reverberated through Los Angeles on January 17, 1994, forever altered the landscape of Southern California. At 4:30 a.m., the ground shook violently as the 6.7 magnitude Northridge earthquake struck, unleashing destruction of unprecedented proportions. Buildings crumbled, bridges collapsed, and freeway lanes entangled like a collapsed Jenga puzzle, leaving behind a scene of devastation. In its wake, 57 lives were lost, and the economic toll amounted to an equivalent of $90 billion in today’s currency.
The haunting memories of that fateful day endure, particularly among the individuals who played pivotal roles in the response and recovery efforts. First responders, building engineers, and seismologists, in particular, carry vivid recollections of the catastrophe. As the 30th anniversary of the Northridge earthquake approached, many took the opportunity to reflect on the progress made in bolstering preparations for future calamities, while also emphasizing the importance of remaining vigilant.
PUBLIC PREPAREDNESS
Mark Benthien was a student studying geophysics when the powerful earthquake shook him awake.
“I remember my belongings were hurled across the room and scattered on my floor. I had to walk through the mess to even find my shoes,” he said.
Thirty years later, he is the director of Communication, Education and Outreach at the Southern California Earthquake Center (SCEC). Headquartered at USC, SCEC is a research organization funded by the National Science Foundation and the U.S. Geological Survey that aims to gather data on earthquakes, interpret that data and communicate those understandings to build a resilient, earthquake-prepared community. The non profit organization partners with different institutions around the world to create a virtual network of collaboration and advocacy.
As the director of Communication, Education and Outreach, Benthien focuses on making sure the public is informed and prepared for the next major earthquake. One of the largest projects he coordinates every year since its inception is the Great ShakeOut earthquake drills.
“Since 2009, we’ve taught thousands of students the proper way to protect themselves during an earthquake,” he said. “The Great ShakeOut began as a one-time, statewide event to commemorate the 15th anniversary of the Northridge Earthquake. The goal was to get as many students across the state to Drop, Cover, Hold On for one day. Now, fifteen years later, we are teaching millions of people around the world to practice this.”
Benthien also manages the Earthquake Country Alliance, a non profit organization under SCEC that attends and hosts events across California (otherwise known as “Earthquake Country”) to help communities stay informed and prepared for the next big one.
The Great ShakeOut now operates in all fifty states and U.S. territories in addition to countries like Japan and New Zealand. Additionally, anyone around the globe is encouraged to participate. While the internationally recognized earthquake drill lends most of its participation data to schools, the Great ShakeOut is open to all types of organizations, including businesses, hospitals, clinics, non-profits, local and federal government offices and many more. Benthien says the Great ShakeOut has impacted many young people across the state.
“Whenever I go to events and talk about earthquake preparedness to families, I always ask the kids first, ‘What do you do during an earthquake? What do they teach you in school?’, and the majority of the time, the kids will know to Drop, Cover, Hold On and the parents won’t,” Benthien said. “We know that earthquake preparedness is a personal responsibility and the younger generations are a key demographic for widespread change in the way communities react to seismic events.”
SEISMIC ENGINEERING
On the 30th anniversary of the Northridge Earthquake, a symposium in Pasadena at the California Institute of Technology brought together policymakers, seismologists, and construction engineers to reflect on the seismic event and discuss strategies for mitigating future risks.
Dr. Lucy Jones, a renowned expert in earthquake science, underscored the role of individuals in safeguarding themselves against potential hazards. She emphasized the significance of structural integrity in buildings, particularly highlighting the vulnerability of soft-story structures observed during the Northridge earthquake.
“It’s up to you,” Jones said. “Is the bookcase gonna fall on you? Are you gonna lose your grandmother’s china because you put it out on display in a way that isn’t hooked down?”
She emphasized the significance of structural integrity in buildings, particularly highlighting the vulnerability of soft-story structures observed during the Northridge earthquake.
In an interview with Craig Chamberlain, president of the Structural Engineers Association of Southern California (SEAOSC), he emphasized this vulnerability and explained its importance through the examination of the Northridge Meadows Apartment Complex that sustained significant damage as a result of the Northridge earthquake.
“We saw the second story of that apartment complex crash and collapse on the ground floor structure. It was characterized by a type of building that has these tuck under parking or cars that park underneath one end of the building without having a wall system underneath that area. So when the earthquake happened…it collapsed, the columns that were supporting that and the structure fell down on the first floor,” Chamberlain said.
He continued by saying that most structures with tuck-under parking are now retrofitted thanks to an ordinance by the City of Los Angeles to strengthen these soft-story buildings.
Another structural design flaw that was widespread throughout the Los Angeles area was the design of steel moment frames in buildings. According to the National Earthquake Hazards Reduction Program, damage to welded steel moment frame connections in the Los Angeles area spawned concern about the reliability of established design and construction procedures. A number of buildings experienced fractures in their structures as a result of a flawed design in the columns.
“A moment frame building is a building where the columns (the vertical members) are attached to the horizontal members (the beams) with a very rigid connection,” Chamberlain said. “We thought that this design was very ductile, meaning it could expand and contract like a rubber band but still have its geometry together…it was actually quite brittle. Think of a piece of uncooked pasta in that if you bend it enough, it’s gonna break at some point in time.”
Chamberlain said that the enhancement in the design of steel moment frame structures was a direct result of learning how the previous designs failed after the Northridge earthquake.
Structural engineers, drawing lessons from past failures, acknowledge the strides made in building design but emphasize the ongoing need for improvement. While advancements have enabled buildings to withstand seismic forces, the focus now shifts towards ensuring the functionality and safety of utility systems post-earthquake. This evolution in design aims to enable occupants to remain in buildings safely, with critical systems like air conditioning, electrical, and plumbing remaining operational.
SEARCH AND RESCUE
Firefighter and Public Information Officer with the Los Angeles Fire Department David Ortiz remembers the earthquake that shook the city when he was a young, non-paid “explorer” with the department. He is one of a few firefighters that responded to the earthquake 30 years ago and is still with the department today; most of the colleagues that worked alongside him that day are now retired. While the devastating event was centered in Northridge, Ortiz recalls the effects were felt throughout the entire city and the lessons the fire department learned from them.
“The Northridge earthquake that occurred in 1994 was very significant. It occurred at 4:30 in the morning, where most people in Los Angeles were asleep and it was very devastating because of the deaths that occurred, the damage it caused and it really demonstrated the need for people in California to be prepared,” Ortiz said.
Moments after the Northridge earthquake, the fire department reacted and responded immediately.
“As soon as any earthquake is reported to our dispatch center, the fire department goes into what we call an ‘earthquake mode.’ All fire stations go out and drive their districts focusing on what we call target hazards. We do a drive-by survey, what we call a ‘windshield survey,’” Ortiz said. “We’ll look for any obvious damage, smell for gas leaks, see if there’s any person trapped, any fires”.
It is important to note that in the immediate aftermath of any sizable earthquake, the Los Angeles Fire Department is in triage mode, prioritizing only the emergencies. Firefighters are limited by the size of the department; on any given day, there will be about 1,000 sworn in firefighters actively on duty. In the event of a major earthquake there will likely not be a firefighter for every injury, every fire. Of course, reserve firefighters and partners from around the state will be called to assist, but that help will take time to arrive.
In other words, the actions you take in the moments immediately following the shaking may be the difference between life and death. Emergency preparedness advocates encourage everyone to learn how to use a fire extinguisher so that you can extinguish small fires that may light after an earthquake. Those small fires can quickly grow into much larger fires if there are damaged gas lines around you.
Keep in mind that in the event of a major earthquake, you will not only have to worry about your property, but also that of your neighbors. You may be able to extinguish the small fire at your house, but if your neighbor is not able to extinguish theirs, the flames can quickly spread to your property. On the other hand, you may be in a position where your neighbors are the only people available to help you if you’re in trouble.
Prior to Northridge, during a visit to other earthquakes in Mexico City and in Japan, an LAFD assistant noticed that these cities had empowered their civilians to do a lot more for their communities. He learned more about it and eventually conceived a similar program in the city of Los Angeles. In 1994, the Community Emergency Response Team program, or CERT, was still very young. However, Los Angeles was the first fire department in the U.S. that implemented this program and now it has expanded across the world.
“Fire departments and police departments across the United States now embrace the CERT program. What they do is they teach the citizens to do the basics to be able to fight a small fire with a fire extinguisher, turn off utilities like water or gas to prevent a fire or water damage,” CERT participants are also taught first aid and CPR.
“Empowering these different communities within the neighborhood is a force multiplier for the fire department during times of disaster. CERT is one of the wonderful things that came after Northridge that has benefited the world, particularly the United States,” said Ortiz.
On top of all of these procedures in place by the LAFD and community members to aid during a crisis, there is also a network of firefighting agencies across the state that the department will be able to access in the event of a major emergency.
TRANSPORTATION
Immediately after the event of a major earthquake, it is unlikely that many people will complain about a road or two being damaged, but as we begin to restore our communities, the damages made to our roadways will be noticeable and the effects widespread. The 1994 Northridge Earthquake caused extensive damage to the transportation network of the San Fernando Valley and several other areas. CalTrans reported the collapse of seven state highway bridges and 230 additional ones. While the damage to the bridges was more than expected, the 24 bridges that were previously retrofitted were able to withstand the strong shaking. Due to the extreme delays that bridge closures can have on traffic, CalTrans focused on retrofitting and repairing damaged bridges as a key factor in the opening of damaged roadway networks.
Immediately following the 1994 Northridge Earthquake, two bridges of the Santa Monica Freeway collapsed on Fairfax Avenue. On any given day, an estimated amount of 341,000 cars crossed that section of the freeway. It is one of the most critical points of transportation for the area; at the time, the Los Angeles Times reported it was the world’s busiest thoroughfare. Not only did the city need to rebuild the collapsed bridge as a main connector, but also to expedite restoration processes throughout the Los Angeles area.
Due to the success of A+B contracting after the 1989 Loma Prieta earthquake in the Bay Area, the same type of procurement was used for the bridges of the Santa Monica Freeway. A+B bidding, also referred to as cost-plus-time bidding, is a method of determining the lowest responsible bidder for projects by requiring contractors to competitively bid the construction cost and the number of working days to complete all work. In other words, this model created an incredible monetary incentive for contractors to work quickly to make repairs, but also meant they would lose out on money for repairs that took too long.
The contractor that won the bid to rebuild the Santa Monica Freeway bridges was C.C. Myers, Inc., a contractor that was hired to do similar work under similar circumstances after the 1989 Loma Prieta Earthquake. Caltrans selected Myers to rebuild two damaged bridges on California 1 near Watsonville. It was the first time officials had used the incentive program, offering $30,000 for each day the company finished early. It was the first time using A+B contracting, so there was a far lower budget than the $200,000 they were offered in the Santa Monica rebuilding project. C.C. Myers, Inc. completed the Loma Prieta collapsed bridges 45 days ahead of schedule.
The use of the A+B contracting model after the Loma Prieta earthquake was experimental, which meant that the Northridge earthquake solidified the success of using this model for future incidents. In May of 1995, the Federal Highway Administration declared that A+B contracting is operational and no longer experimental, citing the Santa Monica Freeway repair as proof of its effectiveness.
A recent use of the contracting model is when the 10 Freeway in Downtown Los Angeles was damaged by a massive fire that began under the Alameda Street overpass in November 2023. Work on repairs began almost immediately after the fire was extinguished and, in collaboration with CalTrans, the contractor was able to finish the job in record time. The freeway was damaged on November 11; it was repaired and reopened in eight days.
In order to prevent further bridge collapses after the Loma Prieta earthquake, Caltrans established the Seismic Advisory Board, an independent body whose role is to advise Caltrans on seismic policy and best technical practices.
Over the past 30 years, Caltrans has invested over $100 million in seismic research that is used to update its seismic design and retrofit policies and standards. After the Northridge earthquake, Caltrans and local agencies undertook a Seismic Safety Retrofit Program that led to the retrofit of 4,931 bridges at a cost of nearly $14 billion. This investment resulted in improvements in seismic design practices and empowered engineers to design resilient new bridges and retrofit existing ones.
“What we learned from Northridge was making sure that, within a structure, that we have balance and stiffness. We needed more stiffness in our bridge designs, specifically pertaining to the columns that keep them up,” Taina said.
After a large earthquake, new bridges are expected to perform well, but may be closed for a short time for inspection and to complete any minor repairs before being quickly returned to service. Bridges constructed or widened using post-1990 Seismic Design Criteria are expected to perform well with a minimal potential for collapse during a design-level earthquake. The performance of retrofitted bridges is expected to be significantly better than those that have not been retrofitted. That being said, it is important for the public to understand that it is impossible for every bridge (any structure, really) to be completely earthquake-proof.
“We do the best to make sure bridges aren’t gonna collapse, and that the roadways networks are gonna be usable, but, it’s not possible to make sure that you’re gonna be able to travel on every roadway, every public street. Mother Nature usually wins…Mother Nature is undefeated. So even though we design and have our best intentions to make sure that there’s minimal potential for collapse during a design-level earthquake, things can still happen. People need to take measures to ensure their personal preparedness,” said Chris Taina, Caltrans Supervising Bridge Engineer.
Although the Seismic Safety Retrofit Program has been completed, approximately 620 additional bridges on the State Highway System have been identified as being vulnerable to seismic activity through recent seismic screenings. Many of these bridges may need retrofitting or replacement. Caltrans continues to fund the seismic retrofit of these bridges through the State Highway Operation and Protection Program (SHOPP), with the goal of reducing this number by 70 percent by 2028, but funding for retrofitting bridges is always a cause for concern for engineers.
“There is a fundamental rule in engineering, that a dollar spent, say for example on bridges,…will buy you a lot more than the same dollar if you are retrofitting old bridges. That’s why retrofitting old bridges costs money,” said Mark Mahan, Caltrans Professional Engineer. “And there’s gonna be a balance on how much money you’re spending, and what kind of a performance you’re going to get out of it, because money is very limited.”
“Taxpayers invest a lot of money in the transportation system through gas taxes and other revenue [Caltrans] receives, so its good for them to know what they can expect and that we’re being good stewards of the resources they’re providing us,” Taina said.
CONCLUSION
As Southern California reflects on the 1994 Northridge earthquake and its enduring impact, the lessons learned serve as a reminder of the ongoing imperative to prioritize preparedness and resilience. Through collective efforts and continued innovation, communities strive to mitigate the risks posed by seismic events, ensuring a safer future for all residents.