Canary Islands, Spain The Canary Islands are part of the Canary Island Seamount Province (CISP) that consists of more than 100 volcanic seamounts. They are part of a hotspot track that extends across the African plate with a very general northeast-southwest age progression. The track begins near Essaouira seamount (68 Ma) and terminates near El Hierro and La Palma (0.4 Ma). It is approximately 1300 kms long and 350 kms wide and trends parallel to the African continental margin. Presently, there is a submarine eruption occurring south of El Age vs distance for Canary and Hawaiian Islands (Carracedo Hierro, extending the track. et al., 1998) The track is not well defined; the distribution of “oldest” ages of the seamounts is varies considerably and the seamount trend is parallel to paleomagnetic anomaly M25 (142 Ma) in the Atlantic seafloor. Ar40/Ar39 data indicate a physical connection between the mantle plume and the moving plate. The most probable model for the plume is shallow mantle upwelling beneath the Atlantic basin that generated Island age trend and overlap of the island aprons (Guillou et al., 2004) recurrent melting from the Late Jurassic to Recent (van den Bogaard, 2013). This is very different than the fixed-plume, deep source, high production Hawaii-Emperor hotspot track. A deep fixed- plume mantle upwelling would have generated a track that trends more east-west. Herman (1975) related the magmatism to a propagating fracture system from the Atlas mountains (trans-Agadir fault) that created a conduit through the lithosphere but this model has significant evidence against it (Guillou et al., 2004). A local extensional ridge may have been active during the Cenozoic but there is little evidence of this either (Fuster, 1975). Arana and Ortiz (1986) suggested compression uplifted tectonic blocks that became the islands and magmatism occurred during relaxation; again, these is little evidence for this model. The mantle plume Oldest ages of seamounts and islands from van den Bogaard (2013). Includes plate motion vector from UNAVCO model convection cell may move horizonally beneath the lithosphere toward the craton, resulting in the long-term volcanism observed on several of the Canary islands (up to 23 my for Fuerteventura). This model was proposed by Geldmacher and others (2005) and Gurenko and others (2006) When the age of just the islands is considered, the track is more defined. The emergent islands extend 490 kms and increase in age toward Africa (east). Islands and seamounts of the Canary Islands (Carracedo and Perez-Torrado, 2013) Ocean Island volcanoes go through a phase of construction followed by destruction; during the destructive phase erosion and mass wasting exceeds volcanic growth and eventually the island is eroded to sea level. Teide volcano represents the peak of the construction phase in the Canary Islands (Carracedo and Perez-Torrado, 2013). Subsidence of the Canary islands is much slower than the Hawaiian islands, this is probably due to the age and thickness of the underlaying lithosphere (Jurassic). Tenerife Tenerife consists of three main shield volcanoes (Roque del Conde massif, Teno and Anaga volcanoes) with compositions ranging from basanites to phonolites. The eruptive history of Tenerife is similar to other ocean islands, growth of main shield volcanoes followed by an eruptive quiescence and then rejuvenation volcanism. The first of the main shield volcanoes developed in central Tenerife (Roque del Conde massif). Erosion and possibly landslides removed the northern flank of the shield. 40Ar/39Ar and K/Ar dates between 11.6 and 8.9 Ma have been obtained (Guillou et al., 2004). The Teno shield formed approximately 6 Ma along the western side of the Central Shield which had entered a quiescence phase. Radiometric ages indicate growth of the Teno shield occurred between 6.1 and 5.2 Ma (Guillou et al., 2004; Longpre et al., 2009). Anaga shield, to the northeast, developed between 4.9 and 4.0 Ma (Guillou et al., 2004; Walter et al., 2005). This series is frequently referred to as the Old Basaltic Series. The rejuvenation phase of Tenerife is represented by Las Cañadas Volcano in the island center starting around 3.5 Ma (Ancochea et al., 1990; 1999; Huertas et al., 2002). The Las Cañadas Volcano is a composite stratovolcano composed of the mafic to intermediate lower group (3.5 – 2.2 Ma) and three felsic cycles of the upper group, the Ucanca (1.59 – 1.18 Ma), Guajara (0.85 – 0.65), and Diego Hernandez (0.37 – 0.175 Ma). Each of these upper group cycles ended with a caldera collapse after a felsic pyroclastic eruption (Ablay et al., 1998). These collapse episodes formed Las Canadas caldera. The Teide Volcanic Complex is the most recent phase of the Las Cañadas Volcano within the caldera. This renewed volcanic activity started around 175 ka. Tiede, Pico Viejo and smaller volcanic vents, including Montana Blanca, produced substantial subplinian phonolitic eruptions around 2 ka (Ablay et al., 1995; 1998). Concurrently, during the past 3 my, rift zones developed to the northwest, northeast and south. The rift zones produced abundant basaltic fissural eruptions and Teide Volcanic Complex produced central felsic magma. Recent eruptions (Teide and Pico Viejo stratocones) are in the northwest and northeast rift zones. These eruptive centers may have helped trigger the lateral collapse of the northern flank of Las Cañadas Caldera around 170 ka. The central volcano experienced progressively differentiated magmas (Carracedo et al., 2007). There have been four recorded volcanic eruptions on Tenerife; in 1704 Arafo, Fasnia and Siete Fuentes volcanoes erupted simultaneously, in 1706 Travejo erupted and a lava flow buried the city of Garachio, in 1798 Pico Viejo erupted and the most recent eruption was in 1909 when the Chinyero cinder cone formed Location and ages of landslides (Mason et al., 2007) along the northwest rift. Teide volcano is the third highest volcano on earth (3,718 m above sea level, >7 km high). Presently, the volcanic hazard on Tenerife is considered moderate because of the low frequency and modest explosivity (Carracedo et al., 2007). A GPS array was installed in 2004 due to seismic-volcanic activity around Teide volcano. Between 2004 and 2009 no significant crustal deformation was identified. A more serious hazard associated with these volcanic islands are submarine collapse events that trigger tsunamis. Landslides on the flanks of volcanic islands generally take two forms, debris avalanches and slumps. A debris avalanche is relatively thin (0.4 to 2 kms thick) with a distinct headwall and a distal deposit of blocky debris. These are rapid, high-energy events. Slumps tend to be gradual down-slope movements of a thick (up to 10 kms) coherent block. Most of the mass wasting events on the Canary Islands are debris avalanches with slumps only identified on El Hierro. Most landslide activity is limited to the volcanically active islands, Tenerife, La Palma, and El Hierro. On average, one landslide occurs every 100,000 years, the most recent occurred on El Hierro approximately 15,000 years ago (Mason et al., 2007). Las Cañadas Caldera (Carracedo and Perez-Torrado, 2013) Harris and others (2011) reported evidence of an ancient collapse event on the southeastern flank of Cañadas volcano. The landslide deposit was up to 50 meters thick and extended over a 90 km2 area. The deposit consists of debris avalanche material with an unsorted matrix. The age of this event has been dated at 733±3 Ka. This landslide event resulted in a gap in the rim of the caldera which subsequently channeled pyroclastic flows to the southeast. Recent volcanism on Tenerife (Carracedo et al, 2007) Carracedo (1994) noted that the rift zones contribute to the mass wasting of the volcanic islands. Gravitational stress, generated by the growth of the volcanic edifices, contribute to the instability and seismicity, associated with magma movement, can trigger mass wasting events. Landslides, enhanced by subsequent erosion, produced many large horseshoe-type scarps and calderas in the Canary Islands. Other hot spot volcanic chains, such as the Hawaiian Islands, experience rapid subsidence after the construction phase ends. The Canary Islands do not subside, possibly due to the thick and old (Jurassic) lithosphere they form on. These ocean islands remain elevated for a long time (20 my old volcanics are observed on the islands) and are more susceptible to gravitational collapse. Gee and others (2001) identified four different landslides on El Hierro. The most recent, El Golfo (SW flank) occurred 15 ka. This is the best described landslide of the Canary Islands. The El Julan landslide (SW flank) occurred >200 ka and is characterized by gravitational slumping. Las Playas (145-176 ka) and San Andres (older) both occurred on the SE. Ward and Day (2001) use geological evidence that suggests that during a future eruption Cubre Vieja Volcano on the island of La Palma may trigger failure of the west flank involving 150 to 500 km3 of rock. They model a tsunami front with a velocity of 100 m/s that would produce a 10-25 m wave on the eastern Americas. The predicted travel time to Florida is approximately 9 hours. Ground water is mined through a large network of infiltration galleries excavated throughout Tenerife. Ground water galleries (Carracedo, 19994) Geologic Time Scale http://www.geosociety.org/science/timescale/ Wednesday, March 12th We arrived in the afternoon, after an exhausting day-long flight from Seattle with layovers in New York and Barcelona. A short bus ride from the Santa Cruz de Tererife airport got us to the bus station in Puerta de la Cruz, on the north shore of the island, walking distance from our hotel. We struggled to pack light for a seven month trip, but with computers, camera equipment, hiking gear and “nice” clothes, it wasn’t easy nor effective.