Things have been busy in these parts. On top of the usual conference-preparation and paper writing, Brian and I are shopping around for a house to buy in Austin.
Home-buying seems to be a part-time job in itself and with Brian long-distance I’ve been doing the leg work to find us a decent place. One of the most interesting aspects so far has been how much science can play a role. It turns out a knowledge of geology can be really helpful in finding good locations for the long-term.
Certain areas of Austin are underlain by clay instead of rock. Clay swells and shrinks based on its moisture content, which can lead to shifts in your foundation. Adding to this propensity for foundation problems is the fact that part of Austin lies over an extensional fault zone. We even have an extinct volcano to show for it. The fault zone was inactive for a long time until a small (3.0 magnitude) earthquake in 2013. Although earthquakes are uncommon, areas in the fault zone are more prone to shifting of the ground below which ends up in cracked foundations.
These aren’t very difficult thing to figure out — geologists have already done the work of finding mapping the different areas. You can look at a geological map of Austin and — if you’re able to understand the legend — you can pinpoint which areas are made of rock and which are made of clay. You can also see the major faults (black lines) and where the fault zone extends. Luckily I’ve learned to do these things in the last year and worked with a real estate agent who was formerly a geologist.
(You can click on the above map for a bigger, zoomable version. Hint: Taylor Group, Eagle Ford, and Del Rio are the main clay formations. Several others, like Navarro and Midway are a clay/sand mixture. I’d much rather have a house built on rock, like the limestone of the Buda or Edwards formations. Here’s a useful table if you’re interested in more info about the different formations.)
Given all the details to consider when buying a home, I’m not eager to add any more complications to the picture. But my developing understanding of geology has given me a little more peace of mind during the process. It’s also helped to narrow my search. Foundation issues aren’t always the most visible thing when looking at homes, so it’s nice to know that I can largely avoid them just by being careful about which neighborhoods I’m looking in.
I should also note that my geologist realtor informed me that building on clay isn’t necessarily a bad thing, but it does require some attention to watering the ground around your house to ensure that there aren’t wild fluctuations in the moisture content of the soil. Around here, that probably means regular watering during times of drought and the hot Texas summers. (You know, the same times there are watering restrictions.) It sounds like you can avoid problems, but I’d much rather avoid inheriting pre-existing foundation issues or having to worry about such things.