Later stages of volcanic evolution of La Palma, Canary Islands: Rift evolution, giant landslides, and the genesis of the Caldera de Taburiente

Abstract

The islands of La Palma and El Hierro form the western end of the hotspot-induced Canary Islands chain. Both islands are at present in the earliest and fastest shield-building stage of growth and show many similarities with the Hawaiian Islands. La Palma shows two very distinct phases of volcanic construction: (1) a Pliocene submarine volcanic and intrusive series, interpreted as an uplifted seamount at least 1500 m above present sea level, and (2) a subaerial volcanic series erupted in the past 2 m.y. Taburiente volcano initially formed the northern part of the island and then extended to the south, forming a ridge (Cumbre Nueva Ridge) that was partially destroyed about 560 ka by a giant lateral collapse (the Cumbre Nueva collapse), possibly involving 180–200 km3 of subaerial volcanic material. The northwest boundary of the Cumbre Nueva collapse formed a vertical scarp that, enlarged by headward erosion, formed the spectacular depression of Caldera de Taburiente. Cumbre Vieja volcano, a north-south elongated rift, forms the southern half of La Palma and constitutes its last stage of growth, including all eruptive activity in the past 125 k.y. Detailed field observations, mapping, and high-precision radiometric dating have allowed reconstruction of the growth and structural changes of the Cumbre Vieja volcano. Interactions between eruption rates, coastal erosion, and glacio-eustatic sea level change allow stratigraphic subdivision of the edifice. The structure of the volcano has been controlled for most of its history by a rift system with a clearly dominant north-south and less-distinct north-east and north-west volcanic rift zones. The rift reorganization of the volcano to a single north-south rift since 7 ka and the opening of faults during the 1949 eruption probably reflect increasing instability of the west flank of the volcano.