Aerial view northwestward shows Katmai caldera and ignimbrite-filled Valley of Ten Thousand Smokes (VTTS), terminus of which is 29 km from center of caldera. Caldera lake and intracaldera glaciers originated after 1923. Lake is now ~250 m deep, and caldera walls extend 250-800 m above its surface. Novarupta vent depression is dark area on valley floor at left, 10 km west of lake center. Upper panels show rhyolitic Novarupta lava dome (380 m across and 65 m high) within 2-km-wide vent depression, which is backfilled by asymmetrical ring of ejecta and marked by arcuate compaction faults.
Credit: Image courtesy of AVO/USGS.