David Amblas

Slope instability along the northeastern Iberian and Balearic continental margins

This paper gathers the available information on submarine landslides identified in the northeastern Iberian continental margin and presents new data on both already known landslides and new, previously unknown ones. The 2,000 km2, 26 km3 resulting deposit of the BIG’95 debris flow in the Ebro margin; the 4 up to 16 km2, 0.4 km3 Eivissa slides in the Eivissa Channel; the 2 up to 65.6 km2, 1.46 km3 Barcelona slides in the shallow southern Catalan margin; and the western Gulf of Lions debris flow in the deep north Catalan margin are presented. This compilation is completed with several other previously undescribed small-scale mass-wasting deposits together with those observed in the Balearic Promontory. The amount and widespreading of submarine landslide deposits in the northern Iberian margins demonstrate that these margins are not an exception to the common occurence of these kind of structures worldwide, and gives an idea on this phenomena recurrence even in margins considered moderately quiet, in terms of seismicity

Submarine canyons and gullies

Submarine canyons are deep incisions observed along most of the world’s continental margins. Their topographic relief is as dramatic as that of any canyon or river valley on land but is hidden beneath the surface of the ocean. Our knowledge of canyons has therefore come primarily from remote sensing and sampling, and has involved contributions from various oceanographic disciplines. Canyons are a critical link between coastal and shelf waters and abyssal depths; water masses, sediment, nutrients, and even litter and pollutants are carried through them. Advances in technology continue to provide new insights into canyon environments by pushing the frontier of deep marine observations and measurements. In this chapter we describe the main geomorphic features of submarine canyons and what is known about their formation and the processes that shape them. We also consider submarine gullies, which are small valleys commonly found within or alongside submarine canyons on the continental slope and may represent an incipient stage of canyon development.