Skip to comments.Homes evacuated in Texas as ground shifts below (San Antonio)
Posted on 01/25/2010 10:22:53 AM PST by NormsRevenge
SAN ANTONIO Dozens of homes were evacuated in San Antonio after the ground below began shifting, creating crevices up to 15 feet deep and nearly splitting a nearby retaining wall in half, officials said.
About 80 homes were first evacuated on Sunday after residents in a northwest side subdivision reported that the ground was caving behind several houses. No one was injured.
The large crack in the retaining wall sent soil tumbling out below. Fences were tossed askew and crumpled like accordions, and aerial photos showed land had given way near the foundations of several homes.
Engineers at the scene Monday were trying to determine why the ground was shifting and how much damage it could cause.
(Excerpt) Read more at news.yahoo.com ...
***The homes were in a new subdivision...***
I wonder if those homes were built over an existing excavation of mines.
Probably build atop limestone, and a sinkhole is forming.
I guess we have a few too many movers & shakers here...
No, Haiti was a natural geological process and this was probably as well, I know there is a lot of limestone in the Austin area and that probably extends down to San Antonio as well. Limestone forms caves, and when a cave gets too close to the surface, you get sinkholes.
I’m losing confidence that votes like this aren’t contingent on bundles of cash exchanging hands. More likely i’m just too naive to have ever believed they did without it. Whores all.
We need to hold down the D.C. power button for 10 seconds and listen for the “tong”.
Looks like house sites are on alluvial fill, too close to the retreating scarp. I doubt that there is a fix for this.
Lots of underground caves/caverns/rivers in that part of Texas. Could just be from an underground cave in.
We’ve had sinkholes opening up in the Tampa Bay area recently. Quite a few along highways. Those photos make it look more like the retaining wall is giving way, and the buildings are sliding...not what we, in Florida, typically see when a sinkhole opens up (probably because everything’s so flat here, it just looks like a hole in the ground.)
Bingo. Seems they ought to do a geophysical survey before building in areas of limestone.
He is probably an Engineering Geologist.
or a previous land fill or dump, something that deteriorates ...
How scary for them.
The aerial shot (Birdseye View) on Bing.com/maps, shows that you are correct. The shot looking east shows that not only were the houses built on fill, there was cut right about where the failure occurred. The cut appears to have been to allow the construction equipment access to both the top and bottom of the slope. Quite likely they didn't properly fill and compact it. (Some of the shots from other directions show the houses already built, some of them anyway, but the one I'm thinking of shows the site prep in progress, but no houses right there.
Sacred Indian Burial Ground (and not covered by homeowner’s insurance).
I just get a kick out of the technical terms “alluvial fill” and “retreating scarp!”
All scarps erode back or "retreat." If you build on a deposit near one, you better be sure that the rates of scarp retreat are longer than human lifespans.
The World According to Scarp.
Holy Cow! Those are some pretty tall ‘retaining walls’.
I’ve seen many developments like this ... the developers find it easier to do monumental terracing in order to build their cookie-cutter desig slab-on-grade houses (designed for flat lots) than to work with the natural terrain and build homes actually designed for non-flat lots.
Looks like the plan is not working out so well.
It is always good to learn something new everyday!
Must be an intriguing profession. I genuinely appreciate the interesting facts.
What he said was they were built on dirt that was hauled in. That is why there is a retaining wall that "is supposed" to keep the alluvial fill (dirt) from slumping down the hill.
Now the short version:
Bad construction and engineering.
“Value engineering” is probably closer to the truth.
Talk about internal conflict. Like a dog that's a Chow/Lab mix. Doesn't know whether to lick you to death or rip your face off.
No, not any underground mines in San Antonio - We are on top of old limestone here, and all quarries are open pit.
Fiesta Texas, for example, is built inside an old gravel pit.
Good old San Antonio again. A few years ago in another subdivision home foundations were cracking a emitting fumes from an old dump they built the development over.
You’re all mistaken, when they checked with o-bow-man he said it was all Bush’s fault.
There that mystery is solved by the chosen one.
It may not have been hauled in -- they could have just used a bulldozer to sculpt out house sites without doing a thorough geological study. I'm sensing big-time lawsuits a'comin'
Bad construction and engineering.
I think I caused it when I buried my life savings in the backyard where the interest rate happens to be higher than at the bank. I just didn’t expect such a small hole to cause such a big problem.
That retaining wall appears to be about 20 feet tall. If the fill was not properly compacted and becomes wet with rain it will behave like a very thick fluid. Assuming the specific gravity of the fill is 2.0 you could easily have 25 psi at the bottom of the retaining wall pushing out. That would mean a force of over 3000 lbs on each square foot.
Can't help but notice what looks like a residential development of some sort in the picture?
Looking a couple of photos and this description it appears the slope of the hill is moving downward. Sounds like poor planning/etc in the developmental stages.
Authorities evacuated about 80 homes in a Northwest Side neighborhood Sunday when ground caved in behind several houses, pushing earth down a 30-foot hill and into two retaining walls that cracked and threatened residences below.
No one was injured, and agencies acted quickly to address the endangered homes near West Hausman Road and Loop 1604.
Describing the collapse as a slope failure, authorities at a Sunday night meeting told residents from The Hills at Rivermist subdivision that in some areas the crevices grew to 12 to 15 feet deep and 6 to 8 feet wide. But they didn’t know the cause.
a home vid but very shaky shows the slope;
A better view showing the area and homes: Note Oak Water that is where some of them were supposedly: Note retaining walls.
or a Geoengineologist
Not even close dude, in Armageddon Bruce Willis and a crew of misfits had to blow up a huge asteroid before it hit Earth. This is a lot more like Earthquake, where Charlton Heston and Ava Gardner try to survive after a huge earthquake hits Los Angeles.
I feel that I was denied CRITICAL, Need-to-Know Information.
I saw someone talking about The Phil Schneider Story on the blogs this morning, first time I ever read something like that. Yegads and little fishes!!!
Broke into the wrong G@# D$%& Rec-Room, didn’t it?
Yes, but if you have just a few common household chemicals, in the proper proportions, you can take care of it.
All parties involved will be claiming "it's not my dam fault".
Pedant that I am, it’s obvious that the caption on this thread was written by one of the lefties at AP.
If the ground DID NOT shift BELOW these homes, they must have been CAVES.
Then again, since the left has turned the world upside down, the earth in some place is actually ABOVE these homes.
Satan trying to escape hell to get away from Teddy Kennedy?
(with due regards to previous thread)
LOL. At least it’s not “Dante’s Peak” or “Avalanche!”
The Crownridge area of San Antonio is across the northern rim of the city (hence the name 'Crownridge") and is where the Texas Hill Country starts building up from the Coastal Plain. Although the area is very rocky, it is not necessarily stable.
Typical subdivision construction in these areas involves excavating a hillside to create a level building site, exposing bare rock outcroppings on the hillside. These exposed hillsides are often covered with a stone veneer wall or a commercial product such as Pavestone blocks.
The assumption on the part of the builders is that the rock substrate is stable enough to support itself and everything built on top of it. The 'retaining walls' described in this story have no structural purpose at all - they are used to simply provide a more attractive view of what would otherwise be an exposed hillside.
As others on this thread have noted, this area is rife with limestone which is a rather soft and porous rock. While there are caves up towards Austin, I do not believe there are any underground caves or caverns in Bexar County.