The launch of a new GVP website is scheduled for Monday, May 20, 2013.
The 22-km-wide Valles caldera in northern New Mexico was formed during a series of major eruptions ending with the eruption of the Bandelier Tuff about 1 million years ago. Post-caldera uplift formed a large resurgent dome in the center of the caldera. The latest eruptions occurred about 130,000 years ago, but geothermal activity continues. This view from the caldera moat shows the rim of the 1.45 million-year-old Toledo embayment to the north, with the edge of the Cerro del Medio rhyolitic lava dome at the extreme left.
Photo by Lee Siebert, 1989 (Smithsonian Institution).