Los Angeles Earthquake Preparedness: Neighborhood-by-Neighborhood Guide

Los Angeles does not have an earthquake problem in the way that a city might have a traffic problem or an air quality problem — something generated by human activity that could, in principle, be managed away. LA has an earthquake condition: a permanent, geological feature of the landscape that predates the city by millions of years and will outlast it by millions more. More than 500 mapped fault traces run beneath the Los Angeles Basin. The San Andreas Fault — 45 miles from downtown at its closest — is capable of a M7.8 that USGS ShakeOut scenario analysis estimates would kill 1,800 people, injure 53,000, and cause $213 billion in damage in the first two weeks. The Puente Hills blind thrust fault runs directly beneath the urban core at depths of 5–15 kilometers, invisible on the surface but capable of M7.0–7.5 directly under the city's highest-density neighborhoods.

Most LA residents know, in a general way, that they live in earthquake country. Very few know which specific fault is closest to their home, what their building's vulnerability profile actually is, which neighborhoods will experience the worst ground shaking in the next major event, or what the difference is between knowing all of this and doing nothing versus taking the specific actions that meaningfully reduce the probability that the next earthquake kills someone in their household. This guide attempts to close that gap — neighborhood by neighborhood, building type by building type, fault by fault.

The Fault Systems That Matter for LA

Los Angeles sits within the broader Pacific-North America plate boundary zone — the tectonic setting responsible for California's seismicity — where the Pacific plate moves northwestward relative to North America at approximately 50 mm per year. Most of this motion is accommodated on the San Andreas Fault, but 15–25% is distributed across a network of secondary faults throughout the Los Angeles Basin and surrounding ranges, each capable of generating damaging earthquakes in their own right.

The San Andreas Fault: The Big One's Origin

The San Andreas Fault runs roughly 45 miles northeast of downtown Los Angeles at the base of the San Gabriel Mountains — close enough that a major rupture will be felt severely in the city, but far enough that the ground motion attenuates with distance before arriving at the urban core. The southern San Andreas — from the Salton Sea through the Inland Empire to the Mojave — has not experienced a major rupture since 1857, when the M7.9 Fort Tejon earthquake ruptured more than 300 miles of fault surface. That represents more than 160 years of accumulated strain at roughly 25 mm per year — approximately 4 meters of slip deficit that will be released in a future earthquake estimated by UCERF3 at M7.8 for the full southern section rupture.

The USGS Great California ShakeOut scenario, updated most recently in 2023, models a M7.8 rupture from the Salton Sea to Lake Hughes. Downtown Los Angeles would experience Modified Mercalli Intensity of VII–VIII — strong to very strong shaking lasting 30–60 seconds. The San Fernando Valley, closer to the fault trace, would experience VIII–IX. Soft-soil areas along the LA River corridor and in the lowland parts of the San Gabriel Valley would see the highest amplification.

The Puente Hills Fault: The Hidden Urban Threat

More immediately threatening to the urban core than the San Andreas is the Puente Hills blind thrust fault system — a northeast-dipping reverse fault that runs beneath the Los Angeles Basin from the Whittier Narrows westward under downtown LA, Hollywood, and into the San Fernando Valley. It has no surface expression — no fault scarp, no visible rupture trace — making it invisible to the standard fault-avoidance setbacks that California applies to surface faults under the Alquist-Priolo Earthquake Fault Zone Act.

The 1987 Whittier Narrows earthquake (M5.9, 8 deaths) was generated by the eastern end of the Puente Hills system. The 1994 Northridge earthquake (M6.7, 57 deaths, $42 billion damage) was generated by the nearby Santa Susana blind thrust — a fault of the same structural family. USGS modeling of a full Puente Hills fault rupture estimates M7.0–7.5 with the epicenter beneath the most densely populated part of the Los Angeles Basin. The scenario loss estimates for a Puente Hills M7.0 are broadly comparable to the San Andreas M7.8 despite the smaller magnitude, because the source is so much closer to the urban concentration.

The Hollywood, Santa Monica, and Raymond Faults

A series of east-west trending faults runs through the heart of the Los Angeles Basin, cutting directly beneath the city's most densely populated neighborhoods:

• Hollywood Fault: Runs east-west through Hollywood, Griffith Park, and Los Feliz at shallow depth, separating the Santa Monica Mountains from the LA Basin. A M6.0–6.5 source directly beneath some of LA's highest residential densities. Not fully mapped; likely extends further east and west than currently charted.
• Santa Monica Fault: Runs along the base of the Santa Monica Mountains from Santa Monica through West Hollywood to Hollywood. The 1994 Northridge earthquake activated related structures in this system. Buildings in the Mountain-to-Basin transition zone along Sunset Boulevard and Mulholland Drive sit in proximity to active fault traces.
• Raymond Fault: Runs east-west along the base of the San Gabriel Mountains foothills from Sierra Madre through Arcadia, Monrovia, and into Pasadena. A M6.5–7.0 source for the foothill communities. Last major surface rupture approximately 1,000 years ago based on paleoseismic trenching.
• Sierra Madre / Cucamonga Fault System: The thrust fault front at the base of the San Gabriel Mountains, running from Sierra Madre east through Rancho Cucamonga. Capable of M7.0–7.5. The foothills communities of Arcadia, Monrovia, Sierra Madre, Claremont, and Upland sit in the high-hazard zone for this system.

The Newport-Inglewood Fault: The Coastal Threat

Running northwest-southeast from Beverly Hills through Culver City, Inglewood, Hawthorne, Lawndale, Torrance, Carson, and Long Beach to the Newport Bay area in Orange County, the Newport-Inglewood Fault is a right-lateral strike-slip fault responsible for the 1933 Long Beach earthquake (M6.4, 115 deaths) — the event that produced California's Field Act mandating seismic design for school construction. A full rupture of the Newport-Inglewood is estimated at M7.0–7.4, with severe shaking in the South Bay, Long Beach, and coastal areas where the fault passes closest to high-density residential neighborhoods.

The Whittier-Elsinore Fault System

The Whittier Fault and its southern extension the Elsinore Fault run northeast of downtown LA through Whittier, La Habra, and the Puente Hills — separate from but adjacent to the Puente Hills blind thrust. The Whittier segment is capable of M6.5–7.0 and represents the primary seismic hazard for the communities of East LA, Montebello, Pico Rivera, and the eastern San Gabriel Valley.

Neighborhood Hazard Profiles

The following profiles synthesize fault proximity, ground shaking intensity (from USGS ShakeMaps and UCERF3-based scenario analyses), soil conditions (from CGS Seismic Hazard Zone maps), and dominant building types for each major LA district. Tags indicate the primary hazard factors for each area.

The Two Building Types That Kill the Most People

Across all of LA's neighborhoods, two building categories account for the majority of projected earthquake fatalities in every major scenario analysis: unreinforced masonry (URM) and non-ductile concrete frame buildings. A third category — soft-story wood-frame apartments — accounts for the majority of displaced residents even when death tolls are lower.

Non-Ductile Concrete Buildings: LA's Most Dangerous Stock

Non-ductile concrete buildings — reinforced concrete frame structures built before approximately 1980 without the ductility provisions that modern codes require — are the building type most likely to kill their occupants in a major LA earthquake. The 1971 Sylmar earthquake collapsed the Olive View Medical Center (non-ductile concrete). The 1994 Northridge earthquake collapsed the Kaiser Permanente Panorama City building (non-ductile concrete), numerous parking structures (non-ductile concrete), and damaged hundreds of apartment and commercial buildings of the same type. FEMA estimates approximately 13,500 non-ductile concrete buildings exist in LA County alone.

Los Angeles passed a mandatory retrofit ordinance for non-ductile concrete buildings (Ordinance 184081) in 2015, requiring owners to conduct seismic assessments and — for the most vulnerable structures — complete retrofits. Compliance deadlines have been extended multiple times, and as of 2026 a significant fraction of the mandated buildings remain at various stages of the assessment and retrofit process. You can check the compliance status of any specific building in LA at the LADBS website using the address or permit number.

Soft-Story Wood-Frame Apartments: The Mass Displacement Engine

Soft-story apartment buildings — typically three-story wood-frame buildings from the 1950s–1970s with an open ground-floor parking level — are the single most common residential building type in central LA and the most likely to be severely damaged or to partially collapse in a major earthquake. The soft story at the ground level provides insufficient lateral resistance: during the 1994 Northridge earthquake, hundreds of these buildings collapsed or were rendered uninhabitable, displacing tens of thousands of residents. The Northridge Meadows apartment complex collapse — which killed 16 people in their sleep — was a classic soft-story failure.

LA's mandatory Soft-Story Retrofit Ordinance (enacted 2015) required all soft-story wood-frame buildings with 2 or more stories and 5 or more residential units on soft, weak, or open-front ground floors to be retrofitted. As of 2026, the majority of the approximately 13,500 buildings subject to the ordinance have either completed retrofits or are in process. However, buildings with fewer than 5 units — the smaller duplexes and triplexes that make up a significant fraction of LA's residential rental stock — are not covered by the ordinance and remain unretrofitted. To check your building's status: ladbs.org → Permit & Inspection Report → enter your address.

Ground Failure Hazards: Liquefaction and Landslides

Liquefaction Zones

Liquefaction — the process by which saturated, loose, sandy soils temporarily lose their strength and behave like a liquid during sustained earthquake shaking — affects a significant portion of the Los Angeles Basin. The California Geological Survey has mapped liquefaction hazard zones across the state; areas of high susceptibility in LA include the Venice Beach coastal strip and canals, the lower LA River corridor from downtown to Long Beach, the harbor area of San Pedro and Long Beach, low-lying portions of the San Fernando Valley (particularly near the Chatsworth Reservoir and the Van Norman Complex area), and sections of the coastal plain from El Segundo through Hawthorne and Compton.

Liquefaction does not typically kill people directly — buildings on liquefied ground tend to settle, tilt, or have their foundation systems disrupted rather than collapsing catastrophically. The primary consequence is property destruction, utility disruption (buried pipelines fracture when the ground moves around them), and long-term habitability loss. However, in dense urban areas where multi-story buildings sit on liquefiable fill, the foundation failure can be severe enough to trigger structural collapse.

Landslide and Slope Failure Zones

Los Angeles's hillside neighborhoods — the Hollywood Hills, Bel Air, Laurel Canyon, Topanga, Malibu, Pacific Palisades, Palos Verdes, the Glendora/Azusa/Duarte foothill communities — are subject to earthquake-triggered slope failures. The earthquake ground motions that would accompany a major LA event are sufficient to trigger rockfalls, debris flows, and slumps on slopes that are already at marginal stability — a stability that has been reduced further in recent years by the drought cycles and subsequent wildfire burn scars that have killed root systems across the hillsides.

The 2024–2025 Palisades and Eaton fire burn scars are particularly relevant: large areas of slope above Pacific Coast Highway and the foothill communities of Altadena are now in their most landslide-susceptible state in decades, and an earthquake of M6.5+ centered in the San Fernando Valley or on the Santa Monica/Hollywood fault system would deliver the ground accelerations needed to trigger large-scale slope failure in these areas.

ShakeAlert: LA's Early Warning System

California's ShakeAlert Earthquake Early Warning System — developed by the USGS in partnership with Caltech, University of Washington, and other institutions — provides seconds to tens of seconds of warning before strong shaking arrives, depending on distance from the epicenter. It does not predict earthquakes; it detects the initial P-wave (the first, less destructive seismic wave) and calculates the estimated shaking intensity and arrival time for the more destructive S-wave and surface waves, broadcasting alerts before the destructive shaking arrives.

For an earthquake on the San Andreas Fault near Wrightwood — one of the most likely M7.8 nucleation points — Downtown LA would receive approximately 30–60 seconds of warning. For a Puente Hills fault event beneath downtown, warning time would be 5–10 seconds or less. For any earthquake where you are very close to the epicenter, ShakeAlert may deliver no warning — the initial waves arrive before the alert can be processed and broadcast. Warning time is proportional to distance from the source.

Water and Utilities: The Post-Earthquake Crisis

A major LA earthquake will disrupt water, gas, and electricity infrastructure across the basin for days to weeks — not because the utilities are unprepared, but because the physical scale of damage to buried pipelines, distribution lines, and substations across the full basin will exceed the capacity to repair them rapidly. LA's water system relies heavily on imported water through aqueducts that cross active fault zones: the Los Angeles Aqueduct crosses the San Andreas Fault at Elizabeth Tunnel; the California Aqueduct and State Water Project cross multiple Transverse Range faults. A major San Andreas rupture will likely disrupt both aqueduct systems, cutting off the majority of LA's water supply within days.

Every household in a seismic zone should have a minimum seven-day water supply stored — one gallon per person per day minimum, three gallons recommended. This is not alarmism; it is the direct recommendation of FEMA, the California Governor's Office of Emergency Services, and the LA Department of Water and Power's own post-earthquake preparedness guidance.

Gas Shutoff: The Single Most Important Action You Can Take Now

Fire following earthquake — the secondary hazard that turned the 1906 San Francisco earthquake into a conflagration that killed far more people than the shaking itself — is the USGS's primary concern in the ShakeOut scenario for Los Angeles. The mechanism is straightforward: earthquake shaking breaks gas lines both inside buildings and in the buried distribution network; ignition sources (pilot lights, sparks from fallen electrical lines, hot appliances) ignite the leaking gas; fires start simultaneously across the basin in numbers that exceed the fire department's capacity to respond, particularly when roads are blocked by debris and water pressure in fire hydrants is reduced by broken water mains.

Every homeowner and building manager in Los Angeles should know where their gas shutoff valve is and should have a wrench capable of turning it stored adjacent to the meter. Automatic seismic gas shutoff valves — devices that automatically close the gas supply when strong shaking is detected — are required for new construction in many LA jurisdictions and can be retrofitted to existing gas meters for approximately $200–400 installed. They do not prevent broken gas lines outside your building, but they prevent your building's internal gas system from adding to the ignition potential. If you smell gas after an earthquake, do not turn on any lights, do not use any electrical switches, open windows and doors, leave the building, and call SoCalGas from outside or from a neighbor's home.

The Practical Preparedness Checklist

The following checklist synthesizes the consensus recommendations of FEMA, CalOES, the Red Cross, the Earthquake Country Alliance, and the USGS into a prioritized action list. Items are ordered roughly by impact per unit of effort — the actions that reduce risk most significantly for the least time and money investment.

Before the Earthquake: The Decisions That Save Lives

• Know your building's hazard status. Check LADBS.org for soft-story and non-ductile concrete retrofit compliance. If your building is on the list and not yet retrofitted, contact the owner or property manager about timeline, or consider your options for alternative housing.
• Enable ShakeAlert on your phone. Confirm that Wireless Emergency Alerts are enabled. Download MyShake or confirm Android Earthquake Alerts are active. These take 10 minutes and cost nothing.
• Store water. Minimum 7 days at 1 gallon/person/day. A 5-gallon refillable jug per person costs ~$15 and lasts months if rotated regularly. Store it somewhere accessible after structural damage — not in a cabinet that may be blocked or jammed.
• Locate your gas meter shutoff and acquire a wrench. A 12-inch adjustable crescent wrench stored on a hook adjacent to the gas meter, with a printed diagram of which direction closes the valve, is a $15 investment. Consider an automatic seismic gas shutoff valve if you own or can negotiate with your landlord.
• Secure your water heater. Unstrapped water heaters are the leading source of gas line rupture and fire ignition in residential earthquakes. Water heater strapping kits cost $20–40 and install in under an hour. Required by California law for all water heaters; many older units remain unstrapped.
• Secure heavy furniture. Bookcases, refrigerators, filing cabinets, and large televisions cause a significant fraction of earthquake injuries. Furniture straps from hardware stores cost $5–15 per item. Bolt tall furniture to wall studs. Move heavy items from upper shelves to lower ones.
• Build a go-bag. 72-hour kit with water, non-perishable food, flashlight, radio (hand-crank or battery), first aid kit, copies of important documents, cash (ATMs won't function), medications (2-week supply), phone charger and backup battery, and comfortable shoes stored near the bed (broken glass is the most common cause of foot injury when people flee barefoot in the dark).
• Establish a household communication plan. Identify an out-of-state contact (easier to reach than local numbers that are saturated post-event). Agree on a meeting point near home and a secondary point outside the neighborhood. Ensure all household members know 911, the out-of-state contact, and the meeting points.
• Know your evacuation routes. Identify at least two ways out of your neighborhood by car and on foot. Identify which roads pass under freeway overpasses (which may collapse) and plan alternatives.

During the Earthquake: Drop, Cover, Hold On

The standard guidance from FEMA, CalOES, and the Earthquake Country Alliance is Drop, Cover, Hold On — drop to your hands and knees, take cover under a sturdy table or desk (or against an interior wall away from windows if no table is nearby), and hold on until the shaking stops. This protects against the most common earthquake injuries: falling objects, broken glass, and structural debris.

• Do not run outside during shaking — the majority of earthquake injuries occur when people try to move during shaking and are struck by falling objects.
• Do not stand in doorways — this is an outdated myth. A doorway offers no more protection than any other part of a modern structure, and you are likely to be struck by the door swinging violently.
• If you are in bed, stay in bed. Pull the pillow over your head. Getting up in the dark to run creates more injury risk than the falling debris that the pillow will stop.
• If you are outside, move away from buildings, utility poles, and trees. Drop to the ground. Do not run into a building.
• If you are driving, pull over away from overpasses, trees, power lines, and buildings. Stay in the vehicle until shaking stops. Do not stop under overpasses.

After the Earthquake: The Critical Hours

• Check for injuries. Administer first aid. Do not move seriously injured people unless they are in immediate danger.
• Check for fires and gas leaks. If you smell gas, shut off the main valve, open windows, and leave. Do not use any electrical switches. Call SoCalGas from outside.
• Inspect your building for structural damage. Look for large cracks in walls, foundation, or chimney. Significant damage to foundations or load-bearing walls may render the building unsafe to occupy. If in doubt, exit and contact a structural engineer or wait for official inspection.
• Expect aftershocks. After any earthquake of M5+, aftershocks are certain. Many will be felt; some may be strong. If you are in a damaged building, leave before aftershocks arrive.
• Do not use elevators until they have been inspected.
• Conserve water immediately — the supply disruption may begin within hours of a major event. Fill bathtubs and available containers while pressure is still available.
• Tune to emergency broadcasts for official guidance on roads, shelters, utilities, and safety. KNX 1070 AM and KFWB 980 AM are LA's primary emergency broadcast stations. LA Emergency Management (@ReadyLA on social media) coordinates official post-event information.

The Bigger Picture: What LA Has Done and What Remains

Los Angeles has made more tangible progress on earthquake preparedness in the past decade than in the previous half-century. The 2015 mandatory retrofit ordinances for soft-story and non-ductile concrete buildings — driven by then-Mayor Eric Garcetti's Resilience by Design initiative and the technical advocacy of seismologists including Lucy Jones — were transformative policy achievements that have significantly reduced the projected death toll in the next major earthquake relative to the pre-2015 baseline. The rollout of ShakeAlert across California has given LA residents an early warning capability that most earthquake-prone cities in the world lack entirely. The Earthquake Country Alliance's annual Great California ShakeOut — the world's largest earthquake drill — has reached tens of millions of Californians with Drop, Cover, Hold On training.

What remains is the harder, slower work. Roughly half of the buildings subject to mandatory retrofit ordinances are still in process. The single-family residential stock — 1940s and 1950s cripple-wall houses on inadequate foundations — is largely outside mandatory programs. Public awareness of specific neighborhood hazards — which fault, which soils, which building type — remains far below what the risk level warrants. The water storage recommendations are followed by a small fraction of LA households despite years of official messaging. And the post-earthquake fire scenario — the aspect of the ShakeOut analysis that keeps seismologists awake at night — has no clear solution that doesn't involve either massively expanded fire suppression capacity or dramatically reduced building density in the highest-risk fire-following-earthquake zones.

The next major Los Angeles earthquake will not be a surprise. The geology has been described. The faults have been mapped. The building types have been identified. The scenario analyses have been published and updated and published again. The only variable the next earthquake cannot predict is whether the household reading this prepared for it or assumed that someone else was handling it.