Dinámica de la avalancha de escombros del volcán Cotopaxi – Zona Norte

Abstract

Cotopaxi volcano is one of the largest active stratovolcanoes in Ecuador, located 60 km southeast of Quito and 45 km north of Latacunga. Its proximity to cities and its long history, make this volcano is the subject of many scientific studies. The debris avalanche (DA) of the Cotopaxi volcano occurred approximately 4.5 ka (Mothes et al., 1998) is one of the largest phenomena that marked the Cotopaxi volcano history. Debris avalanche deposit (DAD) is the main information source about this event because the scar is completely covered by recent deposits. The DAD is represented by small hills called "hummocks”, located in the north and northeast of the National Park Cotopaxi. A total of 587 hummocks distributed in the northern and northeastern part of the volcano were identified, which present facies derived from the building (andesite blocks), facies derived from the substrate (fine rhyolitic material coming mainly from the Chalupas ignimbrite) and mixing facies. The apparent volume is estimated between 1,067 km3 and 1.21 km3, a range that corresponds to a minimum volume and locates the Cotopaxi AE among the mid-sized debris avalanches in Ecuador. The H / L ratio is a mobility factor calculated at 0.125 in the Cotopaxi AE. The maximum speed reached is 73 m / s. This speed is high compared to other important debris avalanches.