Andagua volcanic field

About

The Andagua volcanic field (also known as Andahua) is a volcanic field in southern Peru which includes a number of cinder cones, lava domes and lava flows which have filled the Andagua Valley (which is also known as Valley of the Volcanoes for this reason). The volcanic field is part of a larger volcanic province that clusters around the Colca River and is mostly of Pleistocene age, although the Andagua sector also features volcanic cones with historical activity, with the last eruption about 370 years ago. Eruptions were mostly effusive, generating lava flows, cones and small eruption columns. Future eruptions are possible, and there is ongoing fumarolic activity. Volcanic activity in the field has flooded the Andahua valley with lava flows, damming local watersheds in the Laguna de Chachas, Laguna Mamacocha and Laguna Pumajallo lakes and burying the course of the Andagua River. The Andahua valley segment of the larger volcanic province was declared a geopark in 2015.

The volcanoes were first mentioned in a 1904 report but scientific investigation began by 1960; owing to the small size of Andagua volcanoes and their remote location they have not gained as much scientific interest as the large stratovolcanoes in the region. Eruptions have been dated on the basis of radiocarbon dating, potassium-argon dating and the morphology of the resulting vents as younger structures are steeper. The term "Andagua volcanic field" has not been used consistently and sometimes the term "Andagua Group" or variants with "Andahua" are used, reflecting the older name of the town; the field is also known as Andagua-Orcopampa volcanic field. The term "Valley of the Volcanoes" is a reference to the volcanoes that fill the valley floor.

The Andagua volcanic field lies in southern Peru, 135 kilometres (84 mi) from the city of Arequipa and within the Arequipa Department and its provinces Castilla, Caylloma and Condesuyos. The towns of Orcopampa, Andagua/Andahua, Soporo, Chachas, Sucna and Ayo lie in its area along with mines and the Inka sites of Antaymarca, Ayo and Jello Jello; economic activity includes farming and mining as well as commerce and industrial activity. There are several mines, some inactive, and several settlements, some ruined. The volcanic field consists of cinder cones, lava domes, lava flow fields, pyroclastic cones, and scoria cones. Lava flows emanated from cones, domes and fractures; some cones have been breached by lava flows. Lava flows reach lengths of 20 kilometres (12 mi) and thicknesses of 80 metres (260 ft); their surfaces are blocky and feature channels. The highest individual volcano is 400 metres (1,300 ft) high although the average height of cones is about 50–170 metres (160–560 ft) or 200–300 metres (660–980 ft) and their width is about 500–650 metres (1,640–2,130 ft); lava domes reach heights of 20–150 metres (66–492 ft). Most of the vents are concentrated in the Valley of the Volcanoes, a 60 kilometres (37 mi) long and 1–9 kilometres (0.62–5.59 mi) wide valley that descends to the Colca River, where they form clusters and alignments which have flooded the valley and tributary valleys with lava flows; most vents are situated on the valley floor while others lie on its flanks. Aside from the Andagua Valley proper, the volcanoes spread across the Apune Valley to the northwest and the Ayo Valley to the south. These are not monogenetic volcanoes as some of them show evidence of multiple eruption episodes. Colours range from grey over reddish to black, with reddish colours appearing on weathered lavas. Young volcanic terrain resembles a moonscape. The valley is flanked by 3,500–5,000 metres (11,500–16,400 ft) high mountains. Among the vents are:

Adapted from Wikipedia (CC BY-SA). Photography via Wikimedia Commons.