Linking subaerial erosion with submarine geomorphology in the western Ionian Sea (south of the Messina Strait), Italy

Abstract

Sediment supplied by continental sources is commonly suspected to have exerted a strong influence on the development of canyons and other morphological features on the continental slopes, but rarely is the sediment supply known sufficiently quantitatively to test this link. Here, we outline an area where offshore morphology, in the western Ionian Sea, may be linked to estimated sediment fluxes produced by subaerial erosion in NE Sicily and SW Calabria. Shelves in this area are narrow (<1 km), and the bathymetry shows that rivers and adjacent submarine channels are almost directly connected with each other. Integrated topographic analyses were performed on a merged digital elevation model (DEM) of ASTER data for subaerial topography and multibeam sonar data for submarine bathymetry. Spatial variations in sediment fluxes from onshore erosion were assessed using a variety of methods, namely: long-term sediment flux from Pleistocene uplift rates, decadal sediment flux from landslide occurrences and published long-term exhumation rates from 10 Be cosmogenic nuclide concentrations. Submarine channels associated with rivers delivering larger sediment fluxes have broad channels, high relief and smooth concave-upward longitudinal profiles. Conversely, submarine channels that lie offshore small-flux rivers have straight longitudinal profiles, low relief and steep gradients. Where river catchments supply a greater sediment flux offshore, shelves tend to be wider (ca. 400 m) and submarine channels have gentler gradients. In contrast, where catchments supply less sediment flux, shelves are narrow (250-300 m) and offshore channel gradients are steeper. The variation of submarine morphology with tectonic uplift rate was also studied, but we find that, unlike onshore terrains where tectonics is commonly an important factor influencing channel morphology, in the submarine landscapes, sediment flux appears to dominate here.

Lithological controls on hillslope sediment supply: insights from landslide activity and grain size distributions

“…Conforti et al ., , ; Bianchini et al ., ; Goswami et al ., ; Santangelo et al ., ). There is a large body of risk‐oriented and monitoring landslide studies in southern Italy (e. g. Terranova et al ., ; Bianchini et al ., ; Giocoli et al ., ), but few studies have evaluated landslides from a landscape evolution or sediment supply perspective (Lazzari and Schiattarella, ; Goswami et al ., , ; Santangelo et al ., ; Antronico et al ., ). Landslide frequency–area statistics have only been evaluated by Goswami et al .…”

“…Multi‐temporal inventories spanning a few years or decades of activity imply landslide rates of between 3.3 and 1.4 × 10 −4 landslides yr −1 km −2 (Petrucci and Polemio, ; Terranova et al ., ; Petrucci et al ., ; Polemio and Petrucci, ; Falconi et al ., ; Polemio and Lonigro, ; Conforti et al ., ; Antronico et al ., ; Goswami et al ., ), although these inventories may be biased towards large, damaging events. A few of these studies provide estimates of landslide‐related catchment erosion rates: 0.46 mm yr −1 (Lazzari and Schiattarella, ), 0.26 mm yr −1 (Antronico et al ., ), and 2.8–3.4 mm yr −1 , albeit for a short‐time period (Goswami et al ., ). Cosmogenic nuclide‐derived catchment erosion rates in Calabria are 0.1–1 mm yr −1 , with a mean value of ~0.5 mm yr −1 (Cyr et al ., ; Olivetti et al ., ); while for the southern Apennines, 10 Be erosion rates and volumetric erosion estimates are ~0.1–0.5 mm yr −1 , with a mean value of ~0.3 mm yr −1 (Amato et al ., ; Lazzari and Schiattarella, ; Gioia et al ., ).…”

“…There is a large body of risk-oriented and monitoring landslide studies in southern Italy (e.g. Terranova et al, 2007;Bianchini et al, 2012;Giocoli et al, 2015), but few studies have evaluated landslides from a landscape evolution or sediment supply perspective (Lazzari and Schiattarella, 2010;Goswami et al, 2011Goswami et al, , 2016Santangelo et al, 2013;Antronico et al, 2015).…”

“…Goswami et al (2011) found β = 1.94; while the data from Santangelo et al (2013) imply a β = 2.16, not dissimilar to the exponent found by Guzzetti et al (2002) in the central Apennines of β = 2.5. Multi-temporal inventories spanning a few years or decades of activity imply landslide rates of between 3.3 and 1.4 × 10 À4 landslides yr À1 km À2 (Petrucci and Polemio, 2000;Terranova et al, 2007;Petrucci et al, 2009;Polemio and Petrucci, 2010;Falconi et al, 2013;Polemio and Lonigro, 2013;Conforti et al, 2014;Antronico et al, 2015;Goswami et al, 2016), although these inventories may be biased towards large, damaging events. A few of these studies provide estimates of landslide-related catchment erosion rates: 0.46 mm yr À1 (Lazzari and Schiattarella, 2010), 0.26 mm yr À1 (Antronico et al, 2015), and 2.8-3.4 mm yr À1 ,…”

“…LITHOLOGICAL CONTROLS ON HILLSLOPE SEDIMENT SUPPLY albeit for a short-time period (Goswami et al, 2016). Cosmogenic nuclide-derived catchment erosion rates in Calabria are 0.1-1 mm yr À1 , with a mean value of~0.5 mm yr À1 (Cyr et al, 2010;Olivetti et al, 2012); while for the southern Apennines, 10 Be erosion rates and volumetric erosion estimates arẽ 0.1-0.5 mm yr À1 , with a mean value of~0.3 mm yr À1 (Amato et al, 2003;Lazzari and Schiattarella, 2010;Gioia et al, 2011).…”