Historic Buildings and Earthquake Risk Across the West
In many Western commercial districts, historic buildings and earthquake risk are closely linked—even if that risk isn’t obvious from the street.
If you own or manage property in a downtown core, an early commercial corridor, or an adaptive reuse district, there’s a good chance the building was designed and built before modern seismic standards took shape, particularly before major code changes in the late 1970s.
While some buildings were updated after that period, those upgrades often focused on new uses or aesthetics rather than overall seismic performance.
These districts continue to thrive economically and culturally. But the way older buildings were originally designed and constructed can still influence how they perform during earthquake shaking. Understanding where some of this older building stock is concentrated helps you better assess earthquake risk—long before retrofit or construction decisions come into play.
Why Older Districts Carry Different Seismic Risk
Older building districts weren’t designed with today’s understanding of earthquake behavior in mind. In many cases, builders completed these structures when seismic codes either did not exist or were far less comprehensive than current standards.
At the time, codes often did not require:
- Wall anchorage or diaphragm continuity
- Reinforced masonry or ductile concrete detailing
As a result, if you own or manage a building in one of these districts, it may include:
- Unreinforced masonry (URM) construction
- Non-ductile concrete structures built before 1978
- Early reinforced systems that don’t perform as intended during seismic events
Over time, ownership changes, renovations, and partial upgrades can further complicate how your building behaves in an earthquake—especially if previous improvements were incremental or lacked a coordinated structural strategy.
Common Types of Older Building “Hubs”
Across the Western U.S., older building stock tends to cluster in predictable ways. You’re more likely to encounter higher concentrations of older construction in:
- Historic downtowns and “Old Town” districts
- Early industrial or warehouse zones later converted to office or retail use
- Main Street commercial corridors developed before World War II
To better illustrate these patterns, here are examples from the five states where Saunders Seismic operates.
California: Historic Downtowns and Early Commercial Cores
California’s older commercial districts often sit directly within active seismic zones. In many cities, historic downtowns developed early and densified quickly, resulting in tightly clustered buildings with shared walls, shallow setbacks, and limited redundancy between structures.
Because of this density, earthquake impacts in these areas can extend beyond individual buildings. Damage to one structure can affect neighboring properties, utilities, and access—making performance and disruption just as important as life safety.
Examples include:
- Old Towne Orange
- Downtown Pasadena
- Downtown Redlands
- Old Sacramento
- Downtown San Jose and Japantown
Oregon: Warehouse Districts and Early Civic Centers
Many of Oregon’s older commercial districts grew around rivers, rail lines, and early industry. As a result, large masonry buildings and early civic structures often sit on softer soils that can amplify earthquake shaking.
In a major Cascadia Subduction Zone event, these districts may experience longer-duration shaking than many owners expect—placing additional stress on older structures and their connections.
Examples include:
- Pearl District and Old Town/Chinatown (Portland)
- Downtown Salem
- Downtown Eugene
Washington: Early Urban Centers Near Critical Infrastructure
Washington’s historic commercial districts often developed near ports, rail corridors, and government centers. These locations make earthquake performance especially important—not just for individual buildings, but for broader continuity of operations.
In past earthquakes, damage to older buildings in these areas has led to prolonged closures, restricted access, and cascading impacts beyond the immediate property.
Examples include:
- Pioneer Square (Seattle)
- Downtown Tacoma
- Downtown Olympia
Nevada: Mining-Era and Early Commercial Districts
Nevada’s older commercial cores frequently trace back to mining and railroad development. Many historic buildings remain in active use despite having experienced limited seismic upgrading over time.
Surrounded by active faults, these districts face earthquake risk that is often underestimated due to the state’s lower public earthquake profile.
Examples include:
- Downtown and Riverwalk (Reno)
- Virginia City
Utah: Railroad and Early Civic Development
Along the Wasatch Front, older commercial districts sit close to one of the most active fault systems in the Intermountain West. Even moderate earthquakes have demonstrated how vulnerable older downtown buildings can be to shaking.
Because many of these districts serve as regional centers, damage can have outsized effects on access, occupancy, and recovery timelines.
Examples include:
- Downtown Salt Lake City
- Downtown Ogden
- Downtown Provo
Where URM Fits Into the Picture
If you own or manage a building in one of these districts, it may fall into categories such as unreinforced masonry, non-ductile concrete, or early reinforced systems that don’t perform well during earthquake shaking.
URM buildings appear especially often in historic commercial cores. Builders designed them to carry gravity loads—not lateral movement—which makes them vulnerable to wall separation, out-of-plane failure, or collapse during seismic events.
Retrofitting Historic and Older Buildings: What You Should Know
Seismic retrofitting doesn’t automatically mean changing your building’s appearance or character.
In many cases, crews complete structural upgrades:
- Behind walls or above ceilings
- At roof or floor diaphragm levels
- Within existing structural bays
Successful retrofit projects help you balance life-safety performance, business continuity, and respect for existing architecture. Early planning becomes especially important if you need to coordinate with historic review boards, tenants, lenders, or insurers.
A Practical First Step
If you own—or are considering purchasing—a building in a historic or older commercial district, the most important step is not jumping straight to retrofit solutions.
Instead, you benefit from understanding how your building is likely to behave during earthquake shaking, where vulnerabilities may exist, and how disruption—not just collapse—could affect your operations.
At Saunders Seismic, we help you evaluate older buildings, coordinate with structural engineers, and plan realistic, cost-conscious upgrades—often well before retrofits become mandatory.
That context helps you make informed decisions.
Ready to Understand Your Building’s Seismic Risk?
You don’t have to guess about earthquake risk—or commit to construction—to get clarity.
A free discovery call with Saunders Seismic gives you the opportunity to talk through your building’s age, type, and location. You’ll gain a clearer understanding of how it’s likely to perform during earthquake shaking and whether a retrofit may be needed.
There’s no pressure and no obligation—just an informed conversation grounded in decades of seismic retrofit experience across the western U.S.
Contact Saunders Seismic today and take the first step toward confident, well-informed decision-making.