The dark streak descending the NW flank of the caldera of Hudson volcano is a lava flow that was erupted during the initial stages of the 1991 eruption. During the first two days of the eruption, August 8-9, basaltic ash and lava were erupted from a 4.5-km-long fissure on the western caldera rim. The lava flow traveled 4 km down the Huemules glacier. Ash from the August 12-15 paroxysmal eruption, which originated from a subglacial vent whose margin is just visible at the extreme left, darkens the caldera floor in this August 23 photo.

Photo by Norm Banks, 1991 (U.S. Geological Survey).

This image is made available as a Public Domain Work, but proper attribution is appreciated.

Cerro Hudson