BackgroundVolcán San Juan, the NW-most major volcano of the Mexican Volcanic Belt, overlooks the city of Tepic, the capital of Nayarit state. The northernmost of two twin stratovolcanoes is truncated by a 1 x 4 km wide, oval-shaped caldera formed about 15,000 years ago during an eruption that produced thick rhyodacitic pumice-fall deposits. These are up to 9 m thick beneath Tepic and extensively quarried. This major explosive eruption was followed, probably shortly thereafter, by intra-caldera eruptions of andesitic lava domes and flows. Cerro Alto stratovolcano, the 2240 m high point of the San Juan volcanic complex, is an older volcano that rises immediately to the south of San Juan. Reports of historical eruptions of San Juan in 1742 and 1859 are unconfirmed or incorrect (Luhr, 2000).
Source: Smithsonian / GVP volcano information
San Juan Photos
See also: Sentinel hub | Landsat 8