MorePosted By Mike Falk on 2/8/2009 at 1:28 PM
Subsidence is more common than many may realize. USGS Fact Sheet-165-00 cites several examples and causes across America.
Subsidence due to ground water pumping.
Subsidence due to sinkholes and evaporative rock.
Simpler types of vertical movement are evidenced by the age-old axiom to not place bench marks in highway side slopes.
Another thing to consider would be to ask yourself why NGS adopted the NGS 3-D Monument
To read the rest of this thread go to www.i-boards.com/bnp/pob/messages.asp?MsgID=1359886&ThreadID=129287&IsResponse=False#1359886
Subsidence is more common than many may realize. USGS Fact Sheet-165-00 cites several examples and causes across America.
Subsidence due to ground water pumping.
Subsidence due to sinkholes and evaporative rock.
Simpler types of vertical movement are evidenced by the age-old axiom to not place bench marks in highway side slopes.
Another thing to consider would be to ask yourself why NGS adopted the NGS 3-D Monument
To read the rest of this thread go to www.i-boards.com/bnp/pob/messages.asp?MsgID=1359886&ThreadID=129287&IsResponse=False#1359886
