San Francisco’s foundation story is one we’ve been telling for years. Back in 2008, we published our first deep-dive into bedrock vs. landfill zones across the city (I actually know when there’s an earthquake in California before I even know there’s an earthquake because people start searching “Is my home on liquefaction” and web traffic explodes) — an early look at how neighborhoods hold up in seismic shake-ups and which areas are best suited for standing tall when the Big One hits. We then followed up in 2010 with even more granular maps, liquefaction zones, and some great reader resources to get you familiar with those green (safe-ish) and red (uh-oh) areas in SF. Since then, the need to understand liquefaction and seismic zones has only grown, and with new data and tools, it’s easier than ever to check the safety of your slice of the Bay. For those new to the SF market or just curious about the ground beneath their feet, those posts are still worth a read (linked below) — and we’re here to fill in any blanks.

There’s a lot to love about San Francisco’s signature hills and valleys, but let’s talk about what lies beneath those beautiful Victorian facades, mid-century marvels, and sleek modern builds. If you’ve ever found yourself wondering, “Is this home standing on solid ground?” — well, that’s exactly the question we’re diving into today. Because in SF, not all “ground” is created equal. And when it comes to property value and safety, knowing the type of soil (bedrock or landfill) your house sits on can be just as important as knowing your square footage or Walk Score.

Bedrock vs. Landfill: The Basics

Let’s start with a quick geology refresher. San Francisco’s ground composition is a mishmash of bedrock, alluvial (river-based) soils, and — yes — landfill. Bedrock, as you might guess, is sturdy and compact, offering a solid foundation for homes and buildings. Many of SF’s older, iconic neighborhoods like Nob Hill, Telegraph Hill, and parts of Russian Hill are fortunate enough to be rooted in bedrock. Here, buildings generally hold up well in seismic events, and, just as importantly, they offer a safer bet for investors looking to hold steady on property value.

Landfill areas, on the other hand, are made up of debris, loose sediment, or even reclaimed land (hello, Marina District) that was once underwater. Landfill areas pose a few unique challenges: they’re more susceptible to liquefaction during earthquakes, meaning the soil can act like quicksand when shaken. For property values, that risk of earthquake-induced instability means buyers tend to be wary, particularly if they’re looking at longer-term investments.

So, Why Should You Care?

Here’s the deal: the type of soil under your property can directly affect your home’s value, your safety, and — yes — even your peace of mind. With earthquakes a certainty rather than a possibility here in the Bay Area, homebuyers and owners should understand how soil type can affect everything from seismic risk to insurance costs.

If you’re eyeing a property in areas like the Marina, Mission Bay, or parts of SoMa, chances are it’s on landfill. While these areas have a ton of appeal — think waterfront views, trendy restaurants, and easy access to downtown — there’s also that added earthquake risk.

How Does Soil Type Impact Property Value?

The savvy Bay Area buyer or seller knows: property values in SF are influenced by everything from school ratings to local coffee shops. But soil type? That’s one of those sneaky factors that often flies under the radar — until it doesn’t.

In areas known for bedrock, like Pacific Heights, Nob Hill, and Telegraph Hill, property values tend to hold steady (and often appreciate faster) because these areas are perceived as lower risk. Banks and insurers like them more too, which can mean easier loan approval and possibly lower insurance premiums. A strong foundation isn’t just a construction term; it’s a metaphor for rock-solid investment, and buyers are increasingly aware of this.

Now, let’s flip to those landfill areas. While neighborhoods like the Marina and Mission Bay are absolutely on fire in terms of demand, properties here can come with a bit more volatility. This doesn’t mean these areas are bad investments (far from it), but it does mean buyers and sellers need to be aware of the risks — and possibly adjust pricing expectations accordingly.

Want to Know if Your Property Is Bedrock or Landfill?

If you’re curious about what’s under your property, there are some great resources available to explore. You can check out detailed maps from the California Geological Survey and USGS Liquefaction Hazard Maps, which give a comprehensive view of soil types and risk levels in SF neighborhoods. They’re a fantastic tool for buyers, sellers, or even the SF-curious looking to understand their foundation a bit better.

And if you really want to dig in (see what I did there?), our MLS system actually lets us overlay listings with liquefaction maps. Just another perk of working with a real estate team that gets the science behind the soil, not just the listing price.

And let’s face it — while we all hope for a peaceful, shake-free existence here in SF, it’s smart to prepare for the unexpected. So, if you’re thinking of buying, selling, or just getting the full scoop on what lies beneath your property, feel free to reach out. We’ll be happy to walk you through everything, no shovel required.

**** BIG DISCLAIMER: WE ARE IN NO WAY SHAPE OR FORM GEOLOGISTS OR EXPERTS ON SOIL TYPE, FOUNDATIONS, SEISMIC SAFETY OR ANYTHING RELATED TO THE IMPACTS OUR SOIL MAY HAVE ON YOUR (DESIRED) PROPERTY. WE SIMPLY KNOW WHERE TO LOOK FOR GUIDANCE WHEN EARTHQUAKES ARE TOP OF MIND, AND KNOW THAT EVERY SINGLE ONE OF OUR CLIENTS HAS ASKED ABOUT THE LAND UNDERNEATH THEIR PROPERTY, SO WE GUIDE THEM (YOU) TO WHAT YOU NEED TO KNOW AND AREAS THAT ARE ON BEDROCK JUST SO HAPPEN TO BE AREAS THAT HOLD UP IN VALUE. WHETHER THEY ARE RELATED OR NOT IS PURELY CONJECTURE.

– California Geological Survey
– USGS Liquefaction Hazard Maps
– Ask Us: A map of bedrock vs. landfill [theFrontSteps, 2008]
– San Francisco Neighborhoods Prone To Liquefaction And Earthquake Induced Landslides (Bedrock vs. Landfill Take Two) [theFrontSteps, 2010]
– Liquefaction Zones of San Francisco’s Marina District [theFrontSteps, 2015]
– Bay Area Liquefaction, Landslide, and Seismic Zones – Mapped [theFrontSteps, 2016]
– San Francisco / Bay Area Latest Earthquakes, Liquefaction, Landslide, and Soft Story Round Up [theFrontSteps, 2019]
– The Latest SF Liquefaction Zone Maps (for those who must know) [theFrontSteps, 2021]