Chapter 7

Abstract

New results based on modern methods of volcanic mapping and stratigraphy used in the area domain of the Nevado del Ruiz Volcano, combined with the review of previous studies and the contribution of new geochronological, petrographic, and geochemical data, are presented to define the Nevado del Ruiz Volcanic Complex. The geological evolution of this complex consists of four eruptive periods that were characterized by the construction and destruction of volcanic edifices and deposits associated with effusive products (lava flows and lava domes), primary volcaniclastic deposits (pyroclastic density currents and pyroclastic falls), secondary volcaniclastic deposits (lahars and debris avalanches), and glacial and fluvial deposits. The Pre-Ruiz eruptive period was dominated by effusive volcanism and the construction of the "Ancestral Ruiz" volcano; known ages range from 1.8 to 0.97 Ma. The First eruptive period Ruiz corresponded to the construction of the "Older Ruiz" volcano and it was defined by effusive volcanism that started less than 0.97 Ma; the construction of La Olleta Volcano began at the end of this eruptive period at approximately 107 ka, and the destructive period of the "Older Ruiz" volcano occurred at approximately 95 ka, leading to the formation of a caldera. The Intermediate eruptive period Ruiz corresponded to the origin of the volcanoes Piraña and Nereidas and to the continuation of the construction of La Olleta Volcano, as well as the occurrence of other minor eruptive centers. In the Second eruptive period Ruiz the Nevado del Ruiz Volcano was formed; this eruptive period began 66 ka ago. During the last 13 ka, explosive activity has been predominant, at least fourteen pulses and eruptive phases have occurred. The present study provides new knowledge towards understanding the eruptive history of the Nevado del Ruiz Volcanic Complex.

Chapter 3

“…The most recent research (Martínez et al, 2014;Ceballos et al, 2016) was conducted to update the existing volcanic hazard map. The results of detailed volcanological studies in the Nevado del Ruiz are presented in this book (see Ceballos-Hernández et al, 2020) Natives of the region used to call this volcano Cumanday, which means "beautiful bank", while others called it Tama, which means "Great Father" or "Big Father" (Espinosa-Baquero, 2012). The Nevado del Ruiz Volcanic Complex is considered active due to the presence of thermal springs; Holocene, historical, and current activity; high levels of seismicity; ash emissions; and slow dome extrusion at the bottom of the Arenas crater (SGC, https://www.sgc.gov.co/volcanes).…”