Buying a House in Earthquake Country
Parent Q&A
Archived Q&A and Reviews
Questions
- Best Bay Area city if afraid of earthquakes?
- Where are the East bay earthquake hazards?
- Is it really worth it to buy in earthquake country?
- Evaluating earthquake hazards when looking for a house
- Buying a house on a fault trace
- Buying a house on the Blakemont Slide
Best Bay Area city if afraid of earthquakes?
Nov 2011
I've been severely terrorized by the recent earthquakes in light of the fact that the experts say 'the big one' is coming. I've retrofitted my house to the max from top to bottom (structural and belongings and furniture) but it is not helping. I feel like I'm living in terror, since I'm about three blocks from the actual Hayward fault.
I want to move because I've determined that I can't live like this. I don't seem to possess the denial mechanism necessary for living in a fault zone under the threat of an overdue major devastating quake. But where to?
I've narrowed it down to staying in the Bay Area, since around here, quakes are not felt as widely as they are in the rest of the country (in the midwest and east, the rock is older, and, according to the USGS, carries the shaking orders of magnitude further - here, the rock is young and shaking is relatively localized). So what towns are safest in this regard?
I'm currently considering Pleasant Hill and Concord but have no idea how close they are to faults. I can't afford Lamorinda. I currently live in North Oakland and will need to downsize financially if I move, since selling/buying/moving is going to cost me a bundle.
Also: I will need to live in the new town temporarily in a rental, until I sell my house. But I'm scared to death to live in a rental that is not as retrofitted as my current house is, even if the rental is much further from the fault. Which is worse: retrofitted but three blocks from the fault, or 10 miles from the fault and not highly retrofitted?
And any other suggestions on likely towns to move to but still stay in the Bay Area? Terrified of Quakes
OK, take a deep breath. Before you sell your house, educate yourself. There is a wealth of information on the USGS website, as well as the ABAG site (association of bay area governments). You can look at maps of local faults and even find models of what's likely to occur - how far the shaking will be felt, etc - when the big one occurs on a particular fault (or if multiple faults go at once). Spend A LOT of time reading on those two sites before you change your life over this. Proximity to a fault line is important, but so are a few other things... Retrofitting helps a lot. So does living on flat ground. Look into what kind of soil your house is on. Bedrock is better than sandy soil, which is better than landfill. What kind of construction is your house? The safest for earthquakes is single-story, wood-frame construction, of which there is a lot in Oakland. We also live very close to the Hayward fault, and when we were planning our retrofit, we took a lot of comfort from reading studies and stats about past major earthquakes. The buildings that really suffer are multi-story or built on hillsides. Apt buildings... Office buildings... Highways, bridges, overpasses. Read up on this stuff. An apt building 10 miles from the fault could very well be worse than where you are now. Slow down!
Have you considered a floating home? They are built on a barge and move up and down throughout the day with the tide. There are places to mour them as close as Alameda and they can be very charming. If you haven't done so yet, I highly recommend a trip to Sausalito to walk around on the docks and get a sense of the homes. I've often thought that I'd like to live on one, not just for their charm but also because there is (I assume) less risk in a large quake. Of course consulting with an architect/engineer to confirm the sense of this would be advised as I am neither... Best! Don't like to shake either!
I would concentrate on getting a single story wood framed house that is bolted the foundation. That is the safest. Make sure you attach all your bookcases and other heavy furniture to the wall. Don't hang anything above your bed. --Bay Area Lover
Different places vary on how much they will shake during earthquakes, and if the ground is in danger of liquifying. (For example, much of Berkeley is in danger of liquification, including the block where I work. Less than a mile away at my house, I live in a tiny pocket that is not in danger of liquification during an earthquake.) You can check risks for different cities and neighborhoods using the interactive maps on this page: http://quake.abag.ca.gov/shaking/ and liquification: http://quake.abag.ca.gov/liquefaction/ Choose an interactive map, select a fault on the right (like north hayward or the San Andreas) Then click on the map to successfully zoom in on different neighborhoods. Andi
When my husband and I left Oakland, we moved from a house 1/4 mile from the Hayward fault, and there was a quake just a few weeks before we moved, which only made us more certain of our decision to move to Vallejo. Something that helped us determine the location was the following link--maps and information associated with the following site (Association of Bay Area Governments Earthquake and hazards program): http://gis3.abag.ca.gov/Website/Shaking-Maps/viewer.htm http://gis.abag.ca.gov/Website/shakingpotential/index.html
You can study maps by city, county, or even type a specific address into the search, and a map will be shown that reveals fault lines, shaking hazards, etc. It is color- coded, and very easy to zoom in, and determine the most dangerous areas and the least. It also shows active fault lines, and gives information about types of housing that are most at risk, along with retrofit suggestions.
I hope you can look upon this research as a way to learn interesting facts about the area, and find a place where you can feel more comfortable. Good luck! Naomi
Where are the East bay earthquake hazards?
March 2010
We're looking to buy a house and I'm getting confused about earthquake risks. I'm trying to figure out how much more of a significant risk landfill/liquefaction is over shaking intensity. Looking at the ABAG shaking hazard maps, it looks like most of Oakland/Berkeley/Alameda is pretty much screwed for shaking intensity. We like Alameda but have been avoiding the landfill areas for concern of liquefaction. But then we'll get all excited about a house in Oakland near the Hayward fault. Should we stick to our guns and continue to avoid the landfill areas if seismic safety is a concern for us? Or is pretty much the whole East Bay screwed when the Hayward inevitably goes? This may seem too unpredictable, but if the house falls down and kills our family we don't want to feel like we knowingly made a decision that contributed to that. cautious (overly?) househunter
Our understanding of it is that most of the flatlands of the east bay are in a middle category of risk. Land fill areas are about 10 times worse (the equivalent of 1 point on the richter scale) and areas over rock formations are 10 times better. We live in the flats of Berkeley and have done the appropriate sheer wall retrofitting, and I don't worry about our house collapsing in the big one, though there will surely be some damage. I would be less worried about distance from the Hayward fault than about the seismic zone the house is in, though being right on top of a fault might be problematic. Unless a house is in a slide zone, it's not so likely to collapse, and the worst hazards come from within in the form of flying or falling objects, gas line ruptures, etc. I'm not an engineer, but it's well worth the expense to hire one to evaluate any house purchase. Chris
We moved from NY in '05, and I am still NOT jiggy w/this whole earthquake thing!?! We bought a crappy (construction- wise) early 70's house with a gorgeous view (yes, ...stupid suckers!), and after the fact, had a structural engineer come to examine & draw up a set of plans that showed us: a) what was actually 'under the skirts' of the house, and b) what we needed to do to _correctly_ retrofit the house (bolting, sheathing, nailing, etc.). At that point, we had a set of plans that (retrofit) contractors could bid on, apples-to-apples. Then we had one of them do it. Plus, we are on an area we've been told (by someone who built their own home next door) is on bedrock. I would suggest you NOT do what we did: buy w/o first checking out the geology(!); DO have someone qualified do an inspection; DO get a proper retrofit done, by a retrofit specialist (not all contractors know what to do, check their track record!) Then get CORE III certified, and then hope for the best... --should have looked before leaping
Is it really worth it to buy in earthquake country?
Jan 2010
My husband and I dabbled in the home buying market last year but got spooked by the thought of buying a home in earthquake country where the ''odds of a deadly earthquake striking one of California's major seismic faults with a magnitude of at least 6.7 within the next 30 years at more than 99 percent''. (Sfgate, April 2008) I've heard that earthquake insurance is prohibitively expensive. If we put 20% down (150,000) don't we run the risk of losing it all? I know there are many financially-saavy, educated, reasonable people out there and many own homes here...I'm curious how you determined this was a worthwhile investment? grateful for your perspective, jen
This is some advice I heard when I first got here: buy something with a good foundation and spend the money you would have spent on earthquake insurance (for a couple years) on earthquake retrofitting. There's a lot you can do to make sure your house is better prepared, even though nothing is a guarantee. Shake it don't break it
We had the same thought when we moved here from North Carolina. We took out earthquake insurance, which is expensive and has a high deductible - but it made us feel a little better about our choice. A few native Californian friends told us that we were crazy - that no one even bothers with that here. I don't know if that's true, but I do know that earthquakes, fires, and mudslides (in SoCal) are just the downside of living in such a beautiful and naturally vibrant area. Every area has downsides, and you'll get through them one way or another. We've since had an earthquake retrofit done to the house and we cancelled the insurance. Don't make that a reason not to buy here - just make sure earthquake soundness is part of your inspection before you buy - so you know what kind of retrofit you might need to do if you feel it necessary. Rebecca S.
I'm a structural engineer who owns a home in the Bay Area, and I'll be the first to admit that part of doing so, even for a ''financially-saavy, educated, reasonable'' person, is denial. That said, there are some points to considered. Maybe the biggest concern in the engineering community is damage to our water supply from the Delta (old dams), and the ensuing problems following a quake. Light-wood frame structures, which almost all homes are, suffer the least damage of all building types. The strongest considerations are 1) any old brick chimney that's not reinforced and attached to the house is a life-safety hazard, and could cause some structural damage; 2) soft soil (flat areas) could experience exaggerated shaking, as compared with rock (hilly sites) - of course that increases expenses as hills equal views; 3) I would steer very clear of any landfill areas, like much of Alameda and some of Oakland and the Marina District in SF; 4) older foundations were unreinforced without attachment to the home, risking the house sliding off the foundation completely, which would likely mean total structural loss. If you were able to satisfy each of these considerations, you could rest comfortably in your new home, in my opinion. anon
A magnitude 6.5 quake hit California just 2 weeks ago, on January 9. No one was killed, there were no major injuries, and only a handful of houses were badly damaged. Most of the damage was broken glass and things that got knocked off shelves. Luckily it hit in an area that's not too densely populated (near Eureka), but you get the idea. The 6.9 Loma Prieta Quake in 1989 (which I experienced) did a lot of damage, but much of it was to buildings with a specific type of construction: unreinforced masonry or soft-story construction, especially on landfill. Homes with unbolted foundations and no shearwalls were also more vulnerable. California building codes were tightened after that quake, and again after the 1994 quake in LA. Will those building codes protect us in the event of a massive quake? Well, when it comes to an 8.0 we're ALL playing roulette. But if you do your homework about construction types, retrofitting, and liquefaction zones before you buy a home, then that 6.9 will scare the daylights out of you, and may do some damage, but your investment will probably be safe. At least building codes in CA reflect the likelihood of quakes -- you're probably safer here than in Seattle, which has a similar likelihood of a major quake but much more vulnerable buildings and infrastructure.
And of course, you'll want to keep seismic safety in mind when renting, too -- who cares if their money is safe when their family isn't? Cali Girl
There have been major earthquakes in the past and not all of the houses fell down. If a house is properly designed or retrofitted it shouldn't collapse even if in a very strong earthquake. I'm not an engineer but I have engineer friends who own houses along the Hayward quake; apparently they aren't worried! Just make sure you don't buy in an area that was filled in (formerly part of the bay) or otherwise on unstable mud/sand that will liquefy, and have a structural engineer inspect your house before you buy it. -anon homeowner
My perspective is that if you own your home you have the ability to earthquake-proof it really well, whereas as a renter you have no control over the sturdiness of the house or apartment building. Cece
Evaluating earthquake hazards when looking for a house
December 2002
We have recently realized how little we know about seismic hazards. Has anyone found a good book or other resource that explains what to consider when looking at potential houses, schools or daycares? We are concerned about buildings' locations relative to fault lines and other seismic hazards as well as their structural integrity. For example, how risky is it to move into a house or send our kids to a daycare located right on a fault line or in a liquefaction area? Are older, two- story homes in any way less safe than one-story homes? Our ''dream house'' would be a two-story Victorian or craftsman, but someone told us that shaking on a second floor is exponentially worse than shaking on a home's first floor. We would really like to find a good source of information to answer these and other questions that may arise as we think about where we want to live in the Bay Area. Thanks for your suggestions! Kathryn
Nolo press has a great book called ''How to buy a house in California'' that we relied on heavily when buying our home. Jill
Buying a house on a fault trace
September 2002
We are thinking about buying a house that is located on top of a fault trace. Does anyone know what that means, exactly? How bad is it? Someone told us that it could actually be better to be located right on a fault line, because the worst shaking may occur further away. Is there any truth to that? Also, this property has a creek running through it and seems to have a rather high water table (a neighbor told us that she hits water when she digs in her yard). Could the amount of water in the earth make it particularly unstable in an earthquake? Is there a reliable, free source of information about these kinds of things (a government engineer or someone like that) whom we could contact? Thanks! K
From my friend at the USGS - There are active fault traces and inactive fault traces. If the question is about an active trace (part of the Hayward fault zone)....Yikes! The best situation is to be on stable material (bedrock or old alluvium) as far from the fault as possible. The water question is not an idle one, because an elevated water table is often related to the presence of a fault. However, there are lots of fault traces that are not currently active. The best website to find out about predicted shaking is the Association of Bay Area Governments' ''On Shaky Ground'' site, http://www.abag.ca.gov/bayarea/eqmaps/eqmaps.html They also have a lot of other natural hazard info there. That's the place to start.
To find out where a known active fault is, consult the California Geological Survey. Their site is http://www.consrv.ca.gov/cgs .
If the person wants site-specific information, they will have to hire a consulting geologist or geological engineer (He thinks this costs a few hundred dollars). Hope that helps. Angie
This is short, but without knowing this person's situation, the following gives a some idea of potential problems with living on or close to a major fault.
If the house actually straddles the trace of a major fault this is a bad situation that should be avoided. If the home is close (ie.within about 1/8 mile) to the trace this is a little better. However, for very large faults with lots of slip over time (ie. San Andreas fault which has had displacements of hundreds of kilometers) the damage zone can be quite large. This is a zone of crushed rock and defines the fault zone, not just a vertical crack that most people envision the fault to look like. This crushed zone (fault gouge) causes water to accumulate (sag ponds...., San Andreas lake is a good example) and also causes streams to pop up and hence raises the local water table. Saturated crushed rock under strong shaking conditions can result in complete ground failure (liquifaction), not to mention amplifying the ground motion and hence stronger shaking of any structures. With that said, this must all be caveated with some questions, what kind of rock or soil is the home built on? , what fault is the home built next to?, what is the structural integrity of the home? etc. If it is a small fault with little past displacement it is probably not that bad of a situation. Some homes in the Berkeley hills very close to the Hayward fault are actually on fairly competent soil and rock. If the earthquake does not rupture up to the surface, then the shaking near the fault may be comparable to shaking in the flatter parts of Berkeley that are located farther away. However, if the fault does rupture up to the surface this is a very bad situation because this creates much stronger ground shaking right near the fault trace. (as an aside, some of the larger more recent earthquakes in California have failed to rupture up to the surface e.g. Loma Prieta, Northridge).
In summary, it is best to have a home located on stiff soil or rock that is made of wood framing (flexible) that has been seismically retrofitted to prevent cripple wall failure with a good foundation. If the home really does sit on the mapped trace of the Hayward fault for example I would avoid it.
One resource to consider is the California Division of Mines and Geology. I believe they have on-line shaking maps for different earthquake faulting scenarios. -Kevin
Buying a house on the Blakemont Slide
August 2002
We are looking at buying a house in the southern part of El Cerrito and was advised by our agent to look into the ''stability'' of the land upon which houses ar located. We have seen houses we like on Seaview drive but understand that this is in an area called ''Blake Mont Slide'' and that the ground might be less stable here than elsewhere. Is this correct? Does anybody have some updated information/facts on this? The earthquake related maps on the Web does not address the issue of land-slide. As much as we would enjoy having a spectacular view, we wouldn't want waking up one morning finding ourselves at the bottom of the hill or worse) Any insight is greatly appreciated! Per
Hi - When we were looking for a house in the Kensington/El Cerrito area, our realtor strongly advised us against buying any house in the Blakemont slide area. I don't know if Seaview is part of the area, however. I know the slide area includes some streets around the cemetery (below Sunset and above Colusa, I think), but I'm not sure which ones. My impression is that the more experienced realtors know where the slide area begins/ends -- you could also call the city of El Cerrito and the town of Kensington and probably find someone who knows. Good luck. Cathy
We live on Sea View Drive outside the Blakemont slide area. I'm no expert, but I drive through the area daily and have some observations. When we bought our house in 1994, our agent showed us a slide map of the area, so you may want to ask about this map. The slide area is unstable to the point of breaking water lines (EBMUD repair crews are a fixture in the area). During winter, many residents drain their gutters to the street to try to keep water from soaking the soil any more. Most notably, about 1-2 years ago, many of the residents in the slide area were discussing the idea of a tax assessment district to raise money to improve drainage. You should find out about this tax (did it pass? how much is it?). There are a number of documents, including the study prepared for the tax proposal, on the overall situation and your Realtor should be able to provide them to you. Finally, you might want to talk to some of the people living on Eureka between Sea View and Franciscan Way and see what they have to say. Jon
The Kensington Library has a thick file with maps and information on the various homeowner efforts regarding the Blakemont Slide. It's in the slideing file drawers of local stuff.
If I had to say something I would say any area not near a major fault (the Hayward fault and the San Andreas fault are the big ones in the Bay Area). With that said there are a lot of variables that determine how strongly an earthquake is felt in certain areas so there really is no catch-all answer. If safety is a concern, generally speaking most 1-2 story wood structures fare really well in earthquakes. The California Professional Engineer's Act actually allows those structures to be designed by anybody whether or not they are a registered Engineer because of how well they perform. The Bay Area is awash in houses built before Engineers were licensed (circa 1929 if memory serves) and they're still standing. For example my house in Oakland was built in 1924 and has gone through multiple earthquakes. - Structural Engineer
See this map: https://earthquake.usgs.gov/regional/nca/alameda/
Good luck!
In general, the hills are safer than the flats. Here is a map to give you an idea of the different areas and how they measure up. In case it isn't clear, liquefaction is bad, and the lower the liquefaction percentage, the better.
https://earthquake.usgs.gov/regional/nca/alameda/
In general, the closer you are to the bay, the more likely for liquefaction, which means the sandy dirt can liquify like jello and you get what happened in the Marina in SF in 1989 where houses collapsed. These low-lying areas tend to shake more than the neighborhoods closer to the fault line. You will need to look at one of the USGS maps to see the areas that are especially in danger of liquefaction. However, the hills have their problems too. The Hayward fault runs along Highway 13, so a lot of people who live here like me can basically see the fault from their house. The Hayward fault is overdue for a quake. But if your house sits on bedrock, even if it is close to the fault, there is less shaking than in areas further away from the fault, which means less damage. You'd need a structural engineer to evaluate whether a house is sitting on bedrock. The other problem in the hills is mudslides. There are traces of old streams coming down from the tops of the hills that houses have been built on over the years. When there's lots of rain, the water follows its own course downhill, regardless of french drains and whatnot. There are some houses I've seen in Montclair and the Berkeley Hills that have slowly slid down the hill. And then there is fire. The big fires that wipe out entire neighborhoods have usually happened in the hills where there is more vegetation. So in summary, I'm not sure what to say about which areas are safer. But I love the Bay Area, I've lived here for 36 years, so my take on it is to understand what the risks are in my neighborhood, make my house as safe as I can, and be prepared!