El deslizamiento de Bàlitx (Mallorca) y su posible origen sísmico. Procesos activos desde el Pleistoceno superior
- Mateos Ruiz, Rosa María
- Rodríguez Peces, Martín Jesús
- Azañón Hernández, José Miguel
- Rodríguez Fernández, José
- Roldán García, Francisco Javier
- García Moreno, Inmaculada
- Gelabert Ferrer, Bernardí
- García Mayordomo, Julián
ISSN: 0366-0176
Year of publication: 2013
Volume: 124
Issue: 1
Pages: 41-61
Type: Article
More publications in: Boletín geológico y minero
Abstract
The Bàlitx landslide, located on the steep coastal side of the Tramuntana range on the island of Mallorca, is a large translational rock landslide in which the failure surface coincides with the reactivation of an earlier normal fault. The dating of calcite striae on the fault plane with U/Th techniques reveals that the last movement was over 400 kyr ago, which falls outside of the range of this method. The volume of the landslide is estimated to be over 700 million cubic metres, with a north-westward displacement of 300 m. Active extensional cracks as well as block spreads have been identified along the main scarp, together with displacement and toppling of blocks, the beginning of which coincides with oxygen isotope stage OIS 5a (Late Pleistocene = 83 kyr), a wetter and warmer period than the present. Currently active decametre-long cracks up to 50 m wide can be seen to affect the displaced materials. They reveal the rupture of the displaced block into several units at different speeds. A retrospective analysis of slope stability has been carried out, taking into account different scenarios according to three critical sea stands. All the scenarios are stable, with a safety factor of over 1.35. These results support the thesis that the Balitx landslide could have been triggered by seismicity. A study of the Balitx landslide under dynamic conditions reveals that the landslide could have been triggered by a moderate-to-high-magnitude earthquake (Mw.6.0) located close to the landslide (10-30 km) and probably related to some of the active faults identified in Majorca, such as the Palma Fault.