All 31 were later released after being cautioned for holding up the traffic and obstructing a police officer.
In mountain top mining ridge tops are blasted open to look for coal seams. Although miners have to restore the mountain to its original shape the practice can damage the local ecology.
Hannah is a dedicated campaigner for environmental concerns and was also in trouble with the law back in 2006 when she chained herself to a tree in a Los Angeles urban community garden in a protest over its threatened destruction.
Nasa scientist Dr James Hansen was also one of the protestors who were arrested by police.
