I realize the crytalline rock is stable but it is also erosive. There is also sedimentary rock that could have eroded.
There is an important witness. A young girl on the bus stated the 'bus' first went 'up' before it plummeted. That would have been a 'see-saw' effect. In other words the section opposite the school bus would have collapsed first. With the breaking of the structure of the joint where the bus was, there was nothing to prevent it from plummeting down into the river after the initial structure failure.
The bridge would have collapsed 'first' opposite the bus location. If that was the first location of the collapse it could be the riverbed or banks that would have undermined the integrity of the bridge structure.
There are geological integrity issues that the Army Corp could be called on to validate. There are currently mudslides in New Mexico as well due to flooding of the Red River.
Rescuers Search for Minn. Sewer Workers (click here)
Friday July 27, 2007 10:16 PM
By AMY FORLITI
Associated Press Writer
ST. PAUL (AP) - Searchers in boats continued looking Friday for two workers who were feared dead after getting caught by a surge of water in the underground sewer system here and possibly swept into the Mississippi River....
...Kasper said Lametti and Sons, the contractor that employed the two men, had a good reputation for safety. ``It was a fluke thing,'' he said.
According the National Weather Service, nearly a half-inch of rain fell in St. Paul in about 30 minutes.
In neighboring Minneapolis, 16 children and adults were pitched into the water when five sailboats capsized on two city lakes. Authorities said the boaters got to shore safely.
High winds and hail damaged crops, trees, homes and vehicles in the Twin Cities area, authorities said....
I hope this perspective is helpful to all the possibilities. Good luck to all the rescue and recovery efforts. Sympathies to the family of those lost.
Good night.
