Geomorphological reconstruction and morphometric modelling applied to past volcanism

Abstract

Accurate and precise morphometric modelling can be extended to past eruptions after a careful palaeogeomorphological reconstruction of volcanic landforms in an oceanic island. This reconstruction was used to derive the pre-, post-eruption and present-day digital elevation models (DEM). The correct pixel size, interpolation method and quality of these DEMs are discussed. The process in a Geographical Information System framework of the geological information of cone, lava flow and tephra fall deposits together and the aforementioned DEMs allowed the determination of main morphological features of these volcanic landforms and their derivatives. The calibration and validation of morphometric modelling were performed on simulated volcanic landforms, and verified by a case study: a typical Holocene monogenetic basaltic eruption at Gran Canaria Island (Spain).

Geomorphometric variability of “monogenetic” volcanic cones: Evidence from Mauna Kea, Lanzarote and experimental cones

“…(5) is to be expected for cones on a steeply sloping substrate, for which relevant cone height estimates are problematic. In such cases, the most relevant approach is that proposed by Carmichael et al (2006), Favalli et al (2009) or Rodriguez-Gonzalez et al (2010, who derived the cone volume using a pixel-based difference between the cone surface and an interpolated basal surface. Applying Eq.…”

“…Morphometric statistics enabled contrasted average cone shape between volcano cone fields versus platform cone fields to be highlighted (Settle, 1979) or between spatter versus scoria cones (Wood, 1980a). Constraining the absolute volume of pyroclastic material, and its proportion relative to lavas from the same eruption was another focus of interest (Hasenaka and Carmichael, 1985;Carmichael et al, 2006;Rowland et al, 2009;Rodriguez-Gonzalez et al, 2010).…”

“…Assuming that pyroclastic cone material has a porosity of 75% and that DRE volume of pyroclastic material represents 2-25% of the total emitted volume of material in LZCF during the last 1.6 Ma (Ortiz and Diez-Gil, 1989;Rodriguez-Gonzalez et al, 2010), a total erupted volume of 2.4-30 km 3 is derived, or an average of 1.5-18 × 10 6 m 3 ky − 1 . Although this estimate is based on simple assumptions and remains affected by uncertainties, particularly related to the pyroclast/lava relative volumes erupted (which could be more accurately constrained in future studies), it does suggest a magma production rate 1-2 orders of magnitude lower than that estimated over the same period for El Hierro, the westernmost Canarian island (130-400 m 3 ky − 1 ; Carracedo et al, 1998).…”

GIS methods applied to the degradation of monogenetic volcanic fields: A case study of the Holocene volcanism of Gran Canaria (Canary Islands, Spain)

“…The best quality of DTMs for the purposes of this study at the 1:5000 scale, acquired from a cell resolution of 5 × 5 m using the minimum curvature method as the interpolation algorithm. Detailed information about calibration and validation of the obtained DTMs can be found in Rodriguez-Gonzalez et al (2010). Terrain slopes were determined from the DTMs, computed with sufficient smoothing, and using a differential geometry approach based on the weighted averages of all points within the 3 × 3 neighborhood (Warren et al, 2004).…”

Factors controlling the morphology of monogenetic basaltic volcanoes: The Holocene volcanism of Gran Canaria (Canary Islands, Spain)

“…Once the cones were identified, the most common morphometric parameters of a volcanic cone (Wood, 1980a(Wood, , 1980bHasenaka and Carmichael, 1985;Davidson and De Silva, 2000;Corazzato and Tibaldi, 2006;Doniz et al, 2008;Rodriguez-Gonzalez et al, 2010), were determined using GIS software for all volcanic edifices studied ( Fig. 4).…”