Chaitén - Rio Rayas Bridge

Rio Rayas bridge is located 2.5 kilometers (1.5 miles) north-northeast of Chaitén’s caldera rim, in an area that was peppered with gravel-sized tephra on May 6, 2008. The gravel that fell into the forest stripped leaves and small twigs from the canopy and incorporated this organic material into deposits that accumulated on the ground, up to 25 cm (9.8 inches) thick in some places. In the process, tree canopies were severely damaged, having initially lost in excess of 90 percent of their crown, but some species have since sprouted new foliage along their trunks and major limbs, some in as few as 4 months after the eruption. Understory vegetation also was severely affected, but some species, like nalca and bamboo, sprouted from root systems in the pre-eruption soil within the first year.

The river crossed by the bridge, Rio Rayas, flows along the east flank of Chaitén in an area of very thick deposits of sand and gravel tephra from the eruption. Flooding that began shortly after the eruption deposited 1 to 2 meters (3 to 6 feet) of material onto areas along the Rio Rayas. Deposits of a meter ( 3 feet) or more thick killed forests growing in the floodplain.