Callaqui is a stratovolcano

Stratovolcano

A stratovolcano, also known as a composite volcano, is a tall, conical volcano built up by many layers of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic, explosive eruptions...

 located in the Bío-Bío Region

Bío-Bío Region

The VIII Biobío Region , one of the fifteen first-order administrative divisions in Chile, comprises four provinces: Arauco, Biobio, Concepción, and Ñuble.The capital of the Region is Concepción...

 of Chile

Chile

Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

. It is a large ice-capped, basaltic andesite

Basaltic andesite

Basaltic andesite is a black volcanic rock containing about 55% silica. Minerals in basaltic andesite include olivine, augite and plagioclase. Basaltic andesite can be found in volcanoes around the world, including in Central America and the Andes of South America. Basaltic andesite is common in...

 volcano which is elongated in the northeast-southwest direction, due to its construction along an 11 km (7 mi) long fissure. Numerous cinder cone

Cinder cone

According to the , Cinder Cone is the proper name of 1 cinder cone in Canada and 7 cinder cones in the United States:In Canada: Cinder Cone In the United States:...

s and lava flows have erupted from vents along this linear fissure. Most of the activity at Callaqui has been fumarolic. Minor eruptions were reported 1751, 1864, and 1937, and the latest eruption was a small phreatic eruption

Phreatic eruption

A phreatic eruption, also called a phreatic explosion or ultravulcanian eruption, occurs when rising magma makes contact with ground or surface water. The extreme temperature of the magma causes near-instantaneous evaporation to steam, resulting in an explosion of steam, water, ash, rock, and...

 in 1980.

Together with Hekla

Hekla

Hekla is a stratovolcano located in the south of Iceland with a height of . Hekla is one of Iceland's most active volcanoes; over 20 eruptions have occurred in and around the volcano since 874. During the Middle Ages, Icelanders called the volcano the "Gateway to Hell."Hekla is part of a volcanic...

 in Iceland

Iceland

Iceland , described as the Republic of Iceland, is a Nordic and European island country in the North Atlantic Ocean, on the Mid-Atlantic Ridge. Iceland also refers to the main island of the country, which contains almost all the population and almost all the land area. The country has a population...

 Callaqui is one of the few volcanoes with have a morphology between a crater row

Fissure vent

A fissure vent, also known as a volcanic fissure or simply fissure, is a linear volcanic vent through which lava erupts, usually without any explosive activity. The vent is usually a few meters wide and may be many kilometers long. Fissure vents can cause large flood basalts and lava channels...

 and stratovolcano

Stratovolcano

A stratovolcano, also known as a composite volcano, is a tall, conical volcano built up by many layers of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic, explosive eruptions...

(built from mixed lava and tephra eruptions).