The following article is on MSNBC.com. It's really talking about how areas of Cali are sinking, but it mentions Houston was part of a study conducted to see how other cities around the US were "sinking". They say that the USGS measured "long-term sinking in select locations". Not sure what they mean by "long-term", but a previous paragraph refers to "since the late 1940's", so who knows. Well "long-term sinking studies" put Houston as sinking 9 feet. (Whether that's has sunk 9 feet or will sink 9 feet or over what period of time I don't know) : http://www.msnbc.com/news/618081.asp?pne=msn
Actually, the sinking was caused by Thomas "2 sammiches" Hamilton. And Collie ain't helpin none either <img src="http://forums.evilnet.net/ubb/smilies/sprite10.gif"</img>
