More rains coming soon! This could turn into a real big mess. -WaV On Tue, Jan 26, 2010 at 12:43 AM, Gill Edigar <gi...@att.net> wrote:
> It is often said and there is a widespread misconception that the "Balcones > Fault" is "inactive", meaning that it no longer moves. First, the idea that > it is only one fault is inaccurate; it is more correctly a "fault zone" made > up of probably millions of smaller, local faults, some mere meters long, > others well up on the order of dozens of kilometers. And they move; the > seismograph says so. Consider that there are many pre-existing joints and > faults and that would otherwise appear to be 'inactive'. These joints are > filled with mud which dissolves the surfaces of these rocks. As the rocks > are dissolved their center of gravity and their contacts with adjoining > rocks changes or goes away, or rains wash away or introduce clay or other > material. Rains and drouths will alter the mud and moisture content. > Seasonal heating and cooling of the near-surface rocks will affect their > stability. The rock's immediate environment changes over time and it must > adjust itself accordingly. It moves. And that movement, if large enough, > will register on a seismograph; it's a mini-earthquake. There are thousands > of them every day along the length of the (seemingly inactive) Balcones > Fault Zone. > > It is entirely possible, and even likely, that the slumping going on in San > Antonio is a mass of rock spalling along a joint or fault after a lower > side-supporting member has been removed through natural processes or > quarrying and the recent rains have washed out and/or lubricated any clay > binders in the joint. > --Ediger > > > on Mon, Jan 25, 2010 at 11:38 PM, SS <back2scool...@hotmail.com> wrote: > >> The neighborhood was probably built on a landfill...lol. >> >> That's what happens when you cut corners...I hope Centex gets sued into >> bankruptcy. >> >> >> -----Original Message----- >> From: Geary Schindel [mailto:gschin...@edwardsaquifer.org] >> Sent: Monday, January 25, 2010 12:48 PM >> To: tbsam...@verizon.net; texascavers@texascavers.com >> Cc: jrsam...@aol.com >> Subject: RE: [Texascavers] San Antonio sinkholes.. >> >> Folks, >> >> This is not a sinkhole but a classic hill slope failure. Quite impressive >> as slips go. >> >> Geary >> >> -----Original Message----- >> From: tbsam...@verizon.net [mailto:tbsam...@verizon.net] >> Sent: Monday, January 25, 2010 12:32 PM >> To: texascavers@texascavers.com >> Cc: jrsam...@aol.com >> Subject: [Texascavers] San Antonio sinkholes.. >> >> >> "Our backyard has shifted about 10 feet, and everything is pushed closer >> to >> our house," said Sara Koenig, 23. >> >> She and her husband, 27, left early Sunday to study and to volunteer at a >> local hospital, respectively. She said neighbors called her at 11 a.m. to >> report their back fence had collapsed but her two Chihuahuas were safe. >> >> >> >> Near helotes. >> >> http://www.mysanantonio.com/news/82553087.html >> >> >> --------------------------------------------------------------------- >> Visit our website: http://texascavers.com >> To unsubscribe, e-mail: texascavers-unsubscr...@texascavers.com >> For additional commands, e-mail: texascavers-h...@texascavers.com >> >> >> >> --------------------------------------------------------------------- >> Visit our website: http://texascavers.com >> To unsubscribe, e-mail: texascavers-unsubscr...@texascavers.com >> For additional commands, e-mail: texascavers-h...@texascavers.com >> >> >
