These large hills on the outskirts of the city of Huatusco, 35 km from Orizaba, are hummocks of the Jamapa debris avalanche and debris flow deposit, which covers 350 km². The avalanche occurred during the late Pleistocene by collapse of the northern side of Torrecillas volcano, a predecessor to Orizaba, and created a 3.5-km-wide horseshoe-shaped scarp. The rapidly moving avalanche was able to ride up and over a ridge into drainages that do not originate from Orizaba.

Photo by Lee Siebert, 1997 (Smithsonian Institution).

This image is made available under the Public Domain Dedication CC0 license, but proper attribution is appreciated.

Keywords: debris avalanche deposit | hummock | deposit

Pico de Orizaba