Causes, and impacts of lahars generated by the April, 2015 eruption of Calbuco volcano, Chile

Calbuco is a 2015m high, glacier capped, stratovolcano in the heavily populated Los Lagos district of southern Chile (41 degrees 19'48"S 72 degrees 37'06"W) with a history of very large volcanic eruptions in 1893-95, 1906-7, 1911-12, 1917, 1932, 1945, 1961 and 1972. On 22 April, 2015 Calbuco experienced a powerful 90 minute eruption at 18:04h followed by additional major eruptions at 01:00h and 13:10h on 23 & 30 April, respectively, resulting in the evacuation of 6500 people and the imposition of a 20 km radius exclusion zone. These eruptions generated ash plumes up to 15 km high, causing widespread disruption and damage to property to the NE of Calbuco. Hot pyroclastic flows (glowing avalanches) descended into several river catchments radiating from the volcano transforming into hot floods of water and sediment known as lahars which travelled distances of up to 14 km, reaching surrounding populated areas resulting in extensive damage to infrastructure and property.

Although Calbuco, along with other nearby glaciated volcanoes in the Andes, has experienced recent reductions in the size of its glaciers, the current eruption indicates that even volcanoes with small glacier ice volumes can generate significant lahars.

Our scientific goal is to determine the causes, dynamics and impacts of lahars generated during the ongoing Calbuco eruption. To achieve our goals we will undertake fieldwork on the volcano as soon as is practically possible. In the field we'll catalogue the immediate geomorphic and sedimentary impact of lahars on the river valleys systems surrounding Calbuco. We'll Identify lahar wash marks and will survey these use differential satellite positioning systems and ground based laser scanning. We'll conduct a helicopter based laser scanning survey of the lahar channels and will also use an airborne Radar to determine the presence and thickness of any ice left on the mountain after these eruptions. We'll sample and describe the vertical characteristics of these fresh lahar deposits in detail.

The Calbuco eruption provides an exceptional opportunity to examine the dynamics and sedimentary signature of rare hot lahars, as they are still cooling and degassing. We plan to conduct fieldwork as soon as possible before the onset of subsequent volcanic and rainfall-induced lahars which may mask the signature of these earlier events. Our research will contribute to a better understanding of hazardous lahar processes with the hope of reducing the risk to population.

The most immediate beneficiaries of this research will be the Chilean government organisations, e.g. Servicio Nacional de Geologia y Mineria (Sernageomin). We anticipate that our project will help those involved in planning and implementing recovery and management strategies following this volcanic emergency. This group includes the local Chilean population, many thousands of whom have been evacuated on several occasions and for prolonged periods due to the continued maintenance of a 20km exclusion zone surrounding the volcano. We will exchange information and communicate our results to local stakeholders such as Onemi, DGA, Police, regional and city council governments, and affected private industry (e.g. salmon producers, hydropower and water supply). Our research will directly inform agencies responsible for risk communication and risk education in this and many other regions of Chile.

Wider scientific/expert community: Our research will be of interest to the international volcanic and lahar/flood hazard research community. This research will also provide a modern analogue for Quaternary and older volcano-glacial sedimentary systems.

The current eruption and its impacts attracted media attention in Chile and further afield, for example, reaching the UK via the BBC Television News. We anticipate that the ongoing eruption will raise public interest levels in the topic of volcanoes and volcanically-generated lahars. We expect great interest from all three levels of the educational sector as well as from various community groups and individuals and we aim to disseminate our results to help to raise community awareness of the hazards and risks from such events as well as associated planning and mitigation strategies.

We will hold a three day lahar workshop in the city of Puerto Montt where we will present the initial findings of the research with our project partners and other Chilean lahar researchers to key stakeholders (Day 1). We will also host a field trip to view lahar impacts (Day 2) and hold a project team meeting (Day 3) to co-ordinate the final reporting phase of the project.

We will set up a project website in Spanish and English which will provide a photographic and video inventory of the flood impacts surrounding Calbuco volcano. Material from the workshops: talk slides, videos and photos of the field trip will be uploaded to the project website which will be linked to Newcastle University's Centre for Latin American and Caribbean Studies (CLACS). Members of the public worldwide will be able to access this information freely.

We will communicate our research to an interdisciplinary audience via Newcastle University's Centre for Latin American and Caribbean Studies (CLACS) which collaborates with the public, business and charity sectors on dissemination, engagement and knowledge exchange activities.

Publicity materials: We will produce a series of project posters and presentation materials (for display at the stakeholder workshop, local tourist information and visitor centres and at International conferences) to enhance dissemination of key findings. These materials will be in both Spanish and English.

The project results will be used in Newcastle University's first year modules (Introduction to Physical Geography, Geo1020 and Environmental Issues, Geo1005) and in our new 3rd year Applied Geomorphology and Geohazards module.

The project team will present at a number of International conferences including AGU (2015) and EGU (2016).

The project team will prepare a number of publications for submission to international peer-reviewed journals such as: Geology, GSA Bulletin, Quaternary Science Reviews Sedimentology, Earth Surface Processes and Landforms and Geomorphology.