Localized and distributed erosion triggered by the 2015 Hurricane Patricia investigated by repeated drone surveys and time lapse cameras at Volcán de Colima, Mexico

In October 2015, Patricia, a major category 5 hurricane, made landfall in western Mexico, resulting in 500 mm cumulated rainfall and lahar generation along the southerly directed Montegrande valley of Volcán de Colima. We monitored lahar deposition and erosion using time-lapse trail cameras and conducted repeated camera drone overflights, two days before and after the hurricane. Using photogrammetric processing we derive a unique dataset of high resolution digital terrain models and study the geomorphologic impacts of a single lahar event. Results reveal different types of erosion at 8 km distance from the volcano, with overland flow and rill networks, developing into major erosion gullies exceeding a depth of 4 m, as well as bank collapse, oversteepening and marginal erosion. We find alternating deposition and erosion zones that depend on general slope and valley width, and find that the overland flow related erosion is an important contributor to the bulking process of lahars. Moreover, this study shows that camera monitoring is very useful for studying the relationship between volcano landscape evolution and hydrometeorological extremes and for rapid assessment associated with single lahar events.