Search results for "Geology"

Integration of HVSR measures and stratigraphic constraints for seismic microzonation studies: the case of Oliveri (ME)

2014

Abstract. Because of its high seismic hazard the urban area of Oliveri has been subject of first level seismic microzonation. The town develops on a large coastal plain made of mixed fluvial/marine sediments, overlapping a complexly deformed substrate. In order to identify points on the area probably suffering relevant site effects and define a preliminary Vs subsurface model for the first level of microzonation, we performed 23 HVSR measurements. A clustering technique of continuous signals has been used to optimize the calculation of the HVSR curves. 42 reliable peaks of the H/V spectra in the frequency range 0.6–10 Hz have been identified. A second clustering technique has been applied t…

Islands of Fire. Stromboli in the documentary by Vittorio De Seta

2020

The present contribution is based on the methodological approach and on the typical objectives of cultural geography that sees the cultural work as an important source to read the territorial and landscape contexts. Through this paper we then want to critically report about the 1954 short documentary Isole di Fuoco (Islands of Fire), awarded in Cannes, that the director Vittorio De Seta mainly shot on the volcanic island of Stromboli, in Sicily, during an eruption occurred in 1954.

Spatial response spectra and site amplification effects

2002

A simplified analysis of local site amplification effects on the seismic response of multi-support structures is presented. The site effects are modeled by considering reflections and transmission of vertically propagating shear waves from bedrock to the surface through a soil layer. A random vibration-based response spectrum of a simple oscillator on two supports, one of which is founded on rock outcrop and the other on soil layer, is formulated in order to study the influence of non-uniform excitations on multi-support structures. Joint inertial and pseudo-static effects in the overall response are studied in detail. The resulting response spectra are formulated as displacement and force …

Normal vs. strike-slip faulting during rift development in East Africa: The Malawi rift

1992

Kinematic analysis of Neogene and Quaternary faults demonstrates that the direction of extension in the Malawi rift rotated from east-northeast to southeast. Rift development commenced with the formation of half-grabens bounded by northwest-, north-, and northeast-striking normal faults. Owing to slightly oblique rifting, the northwest-striking faults in the northernmost rift segment show a small dextral oblique-slip component, whereas north- and northeast-oriented faults in the central part of the rift display a sinistral oblique-slip component. This first event resulted in block faulting and basin subsidence, which is largely responsible for the present-day basin morphology of Lake Malawi…

Multidisciplinary Approach to Rainfall-Triggered Rockfalls: the Case Study of the Disaster of the Ancient Hydrothermal Sclafani Spa (Madonie Mts., No…

2017

Abstract. In 1851, the region of Sicily experienced many rainstorm-induced landslides. On 13 March 1851, a rainstorm brought about a severe rockfall disaster near the small town of Sclafani (Madonie Mountains, northern-central Sicily, Italy). Rocks detached from the carbonate crest of Mt. Sclafani (813 m above sea level) fell downslope, causing the collapse of the ancient hydrothermal spa (about 430 m above sea level) and burying it under their fragments. Fortunately, the event did not cause injuries or victims. Given its geological, geomorphological and structural features, the calcareous-dolomitic and carbonate-siliciclastic relief of Mt. Sclafani is extremely prone to landsliding. This s…

Single zircon evaporation ages from the Oban Massif, southeastern Nigeria

1998

Abstract A single zircon geochronological study in the Oban Massif of southeastern Nigeria, using the evaporation technique, provides evidence for the existence of Palaeoproterozoic crustal components in the area. The banded gneiss in the Oban village yielded a 207 Pb 206 Pb age of 1931.9±0.8 Ma, whilst charnockites associated with this gneiss provided an emplacement age of 584.5 ± 1.0 Ma. The volumetrically most important intrusive unit in the Oban area is a granodiorite that yielded a zircon age of 616.9 ± 1 Ma. These ages suggest that the banded gneiss is the oldest rock in the Oban Massif and that the emplacement of granodiorite and the formation of charnockites took place during the Pa…

Integrating facies and structural analyses with subsidence history in a Jurassic-Cretaceous intraplatform basin: Outcome for paleogeography of the Pa…

2016

Abstract We illustrate the tectono-sedimentary evolution of a Jurassic–Cretaceous intraplatform basin in a fold and thrust belt present setting (Cala Rossa basin). Detailed stratigraphy and facies analysis of Upper Triassic–Eocene successions outcropping in the Palermo Mts (NW Sicily), integrated with structural analysis, restoration and basin analysis, led to recognize and describe into the intraplatform basin the proximal and distal depositional areas respect to the bordered carbonate platform sectors. Carbonate platform was characterized by a rimmed reef growing with progradational trends towards the basin, as suggested by the several reworked shallow-water materials interlayered into th…

Beach ridges from the Varanger Peninsula (Arctic Norwegian coast): Characteristics and significance

2009

The most common coastal sedimentary forms on the arctic coast of the Varanger Peninsula are raised beach ridge plains. The majority of the ridges consist of coarse material, but there are also sandy beach ridge areas close to the river mouths of some of the major rivers. Some bays having the same isostatic rebound and dynamic conditions have been studied to test if the number of beach ridges in each locality is significant to prove climatic changes, storminess, and rates of sediment accumulation, or if the number of beach ridges in each bay is only dependent on their intrinsic characteristics and self organization. Because the number of ridges varies not only from bay to bay, but even withi…

Badlands in the Tabernas Basin, Betic Chain

2014

The complex badland landscape at Tabernas results from a combination of relief amplitude generated by tectonic uplift since the Pliocene and reactivated several times during the Pleistocene, the properties of the Tortonian sedimentary rocks and a predominantly arid climate. The landscape is dominated by deep incision of the main river systems, which continues in part of the headwater tributaries, and characterized by contrasting slope morphologies and a variety of microecosystems. The Tabernas badlands exhibit a diversity of landforms resulting from the combination of multi-age soil surface components that allow a variety of processes to operate at different rates. These are dominated by ri…

1993

The miocene deposits of the Quesa basin (Betic foreland) outcrops in the central part of the Valencia province (Spain). Quesa basin is a subsiding hanging-wall basin related to an ENE-WSW listric fault system. The deposits of this basin are formed by a 440 metres thick sequence of red clays, containing few intercalations of sandstones and micritic white limestones, and breccias. The upper 70 metres of this sequence is a wedge-shaped unit composed by breccias containing megablocks, wich interfinger with tabular limestones towards the central part of the basin. The breccias are foot-wall derived debris fiow deposits formed during normal faulting. A mammal site close to the base of the breccia…