Shield volcano are cave-like volcanic straights formed by the hardening of overlaying lava. These structures help further the propagation of lava, as the walls of the tube insulates the lava within. Lava tubes can account for a large portion of shield volcano activity; for example, an estimated 58% of the lava forming Kīlauea comes from lava tubes. In some shield volcano eruptions, basaltic lava pours out of a long fissure instead of a central vent, and shrouds the countryside with a long band of volcanic material in the form of a broad plateau. Plateaus of this type exist in Iceland, Washington, Oregon,
Chiles (volcano) Chiles (volcano) Chiles is a volcano on the border of Colombia and Ecuador. It lies south-east of the volcano Cerro Negro de Mayasquer, and the two peaks are considered part of the same Chiles-Cerro Negro volcanic complex. The volcanoes, together with the Cumbal are andesitic in rock type. A 1936 eruption reported by the Colombian government agency Ingeominas may have been from the Ecuadorean volcano Reventador, otherwise the volcano has not erupted for around 160,000 years. On 20 October 2014, the Servicio Geológico Colombiano (SGC) reported that a M 5.8 earthquake, the largest to date, occurred in the vicinity of