Magma emission rates from shallow submarine eruptions using airborne thermal imaging Pedro A. Hernández a,b, ⁎, Sonia Calvari c , Antonio Ramos b,d , Nemesio M. Pérez a,b , Antonio Márquez e , Roberto Quevedo b,f , José Barrancos a,b , Eleazar Padrón a,b , Germán D. Padilla a,b , Dina López b,g , Ángel Rodríguez Santana b,h , Gladys V. Melián a,b , Samara Dionis b , Fátima Rodríguez b , David Calvo b , Letizia Spampinato c a División de Medio Ambiente, ITER, Granadilla de Abona, Tenerife, Canary Islands, Spain b Instituto Volcanológico de Canarias, INVOLCAN, Puerto de la Cruz, Tenerife, Canary Islands, Spain c Istituto Nazionale di Geofisica e Vulcanologia, Obsservatorio Etneo, Sezione di Catania, Catania, Italy d Division of Robotic and Computational Oceanography (SIANI), Facultad de Ciencias del Mar, Universidad de Las Palmas de Gran Canaria, Canary Islands, Spain e Unidad de Helicópteros UTF, Guardia Civil, Zona de Canarias, Tenerife, Canary Islands, Spain f Bionerics Research, Teror-Arucas, Gran Canaria, Canary Islands, Spain g Department of Geological Sciences, OH University, Athens, USA h Departamento de Física, Facultad de Ciencias del Mar, Universidad de Las Palmas de Gran Canaria, Canary Islands, Spain abstract article info Article history: Received 17 April 2014 Received in revised form 11 August 2014 Accepted 14 August 2014 Available online xxxx Keywords: Shallow submarine eruption Thermal airborne monitoring Erupted volume Effusion rate El Hierro Canary Islands The effusion rate is the most important parameter to gather when a volcanic eruption occurs, because it controls the way in which a lava body grows, extends and expands, influencing its dimensional properties. Calculation of lava flow volume from thermal images collected by helicopter surveys has been largely used during the last decade for monitoring subaerial effusive eruptions. However, due to the depths where volcanic activity occurs, monitoring submarine volcanic eruptions is a very difficult task. The 2011–2012 submarine volcanic eruption at El Hierro, Canary Islands, has provided a unique and excellent opportunity to monitor eruptive processes occurring on the seabed. The use of a hand-held thermal camera during daily helicopter flights allowed us to estimate for the first time the daily and total erupted magma volumes from a submarine eruption. The volume of magma emitted during this eruption has been estimated at 300 Mm 3 , giving an average effusion rate of ~25 m 3 s -1 . Thermal imagery by helicopter proved to be a fast, inexpensive, safe and reliable technique of monitoring volcanic eruptions when they occur on the shallow seabed. © 2014 Elsevier Inc. All rights reserved. 1 . Introduction Volcanoes are widely spread out over the seabed of our planet, being concentrated mainly along mid-ocean ridges. Due to the depths where this volcanic activity occurs, monitoring submarine volcanic eruptions is a very difficult task. There have been only two occasions where a deep (N 500 m) submarine eruption has been directly observed, on the West Mata submarine volcano in the northeast Lau Basin, southwest Pacific Ocean (Resing et al., 2011) and at the Monowai submarine volca- no, Kermadec arc (Chadwick et al., 2008). Observations of shallow subma- rine activity have been done at Kilauea and Mauna Loa by scuba divers and remotely operating vehicles, revealing channelized flows and subma- rine lava tubes (Tribble, 1991), pillows and a large amount of fragmental debris formed by lava quenching when entering the sea (Garcia & Davies, 2001; Moore & Chadwick, 1995; Moore, Phillips, Grigg, Peterson, & Swanson, 1973). However, performing long-term monitoring in such an environment is challenging and expensive, and is normally done for short periods of time and through the use of autonomous ocean bottom systems (Deardorff, Cashman, & Chadwick, 2011). Thus, when a subma- rine eruption occurs at shallow depths, there is an excellent opportunity to monitor and study the eruptive activity and test new techniques. Typ- ical phenomena associated with shallow submarine eruptions are floating lava fragments, rising water columns, explosions and discoloration of sea water (Deardorff et al., 2011; Nogami, Yoshida, & Osaka, 1993). Therefore, it is possible to guess the eruption point and intensity of volcanic activity from the color tone, shade and dimensions of the discoloration area (Nogami et al., 1993). When dealing with a volcanic eruption, the effusion rate and Time Averaged Discharge Rate (TADR) are the most important parameters to measure, because they control the way in which a lava body grows, extends and expands, influencing its dimensional properties, such as length, width, thickness, volume and/or area (Harris, Dehn, & Calvari, Remote Sensing of Environment 154 (2014) 219–225 ⁎ Corresponding author at: Instituto Volcanológico de Canarias, INVOLCAN, Puerto de la Cruz, Tenerife, Canary Islands, Spain. E-mail address: phdez@iter.es (P.A. Hernández). http://dx.doi.org/10.1016/j.rse.2014.08.027 0034-4257/© 2014 Elsevier Inc. All rights reserved. Contents lists available at ScienceDirect Remote Sensing of Environment journal homepage: www.elsevier.com/locate/rse