| 1. |
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Carracedo, J. C., et al.
(författare)
-
Evolution of ocean-island rifts : The northeast rift zone of Tenerife, Canary Islands
- 2011
-
Ingår i: Geological Society of America Bulletin. - 0016-7606 .- 1943-2674. ; 123:3-4, s. 562-584
-
Tidskriftsartikel (refereegranskat)abstract
- The northeast rift zone of Tenerife presents a superb opportunity to study the entire cycle of activity of an oceanic rift zone. Field geology, isotopic dating, and magnetic stratigraphy provide a reliable temporal and spatial framework for the evolution of the NE rift zone, which includes a period of very fast growth toward instability (between ca. 1.1 and 0.83 Ma) followed by three successive large landslides: the Micheque and Guimar collapses, which occurred approximately contemporaneously at ca. 830 ka and on either side of the rift, and the La Orotava landslide (between 690 +/- 10 and 566 +/- 13 ka). Our observations suggest that Canarian rift zones show similar patterns of development, which often includes overgrowth, instability, and lateral collapses. Collapses of the rift flanks disrupt established fissural feeding systems, favoring magma ascent and shallow emplacement, which in turn leads to magma differentiation and intermediate to felsic nested eruptions. Rifts and their collapses may therefore act as an important factor in providing architectural and petrological variability to oceanic volcanoes. Conversely, the presence of substantial felsic volcanism in rift settings may indicate the presence of earlier landslide scars, even if concealed by postcollapse volcanism. Comparative analysis of the main rifts in the Canary Islands outlines this general evolutionary pattern: (1) growth of an increasingly high and steep ridge by concentrated basaltic fissure eruptions; (2) flank collapse and catastrophic disruption of the established feeder system of the rift; (3) postcollapse centralized nested volcanism, commonly evolving from initially ultramafic-mafic to terminal felsic compositions (trachytes, phonolites); and (4) progressive decline of nested eruptive activity.
|
|
| 5. |
- Carracedo, Juan Carlos, et al.
(författare)
-
Geological Hazards in the Teide Volcanic Complex
- 2013
-
Ingår i: Teide Volcano. - Berlin, Heidelberg : Springer Berlin/Heidelberg. - 9783642258923 - 9783642258930 ; , s. 249-272
-
Bokkapitel (refereegranskat)abstract
- The island of Tenerife displays contrasted densities of population, from the densely occupied coastal zones (including tourist resorts, airport, energy facilities, etc.) to the sparsely populated forests and mountainous highlands, where most of the recent volcanic events are located. Considering the low frequency of historical eruptions (compared to Hawaii or Reunion Island for example), the assessment of geological hazards must also rely on the analysis and interpretation of prehistorical events, going back to at least the Late Quaternary. In this chapter, we review the hazards related to Teide’s volcanism, but also those from increased seismicity and from slope instability. We discuss the origin of low magnitude earthquakes, and particularly the 2004 episode of unrest. New estimates on cumulative volumes for resurfacing by lava flows during the last few thousand years are provided to serve as a tool for building a lava flow hazard map of Tenerife. Hazards related to explosive activity are also considered and although possible, with phreatomagmatic eruptions being the most likely style anticipated, explosive events are of relatively low probability at Teide in the near future.
|
|
