Search results for "SUBSIDENCE"

Expected future changes in the African monsoon between 2030 and 2070 using some CMIP3 and CMIP5 models under a medium-low RCP scenario

2012

[1] The accuracy of African Monsoon (AM) simulations together with expected future changes are presented using eight available CMIP5/AR5 AOGCMs under the RCP4.5 emission scenario and eight CMIP3/AR4 AOGCMs under the A1b scenario, with a multimodel approach and the “one model one vote” concept. The results refer to the ‘present’ period (1960–1999) and to a ‘future horizon’ (2031–2070), and are discussed in terms of monsoon dynamics and climate change. Overall the new simulations seem more realistic. They exhibit more accurate rainfall patterns, although some biases reported in CMIP3 models remain. The future changes show an inverse tendency regarding rainfall amounts with less (more) rainfal…

Three-dimensional evolution of the Keuper of the Paris basin based on detailed isopach maps of the stratigraphic cycles: tectonic influences

1997

Detailed isopach maps of the stratigraphic cycles of the Keuper of the Paris basin are used to reconstruct the 3D evolution of the basin cycle by cycle and to investigate the influence of tectonic movements. The major base-level cycles record variations in the rate of subsidence in time and space. The area of greatest subsidence, which was confined to the east of the basin during the Scythian–Carnian cycle, shifted northwestwards during the Carnian–Liassic cycle. Within the “Marnes irisees inferieures”, the E–W faults abruptly limited the extent of salt deposits to the north and south by forming a “corridor” where subsidence was greater. The westward shift of areas of subsidence induced by …

Gas emissions and crustal deformation from the Krýsuvík high temperature geothermal system, Iceland

2020

Abstract The Krýsuvik volcanic system is located on the oblique spreading Reykjanes Peninsula, SW Iceland. Since early 2009 the region has been undergoing episodes of localized ground uplift and subsidence. From April–November 2013, we operated near-real time monitoring of gas emissions in Krýsuvik, using a Multi-component Gas Analyzer System (Multi-GAS), collecting data on gas composition from a fumarole (H2O, CO2, SO2, H2S). The dataset in this study, comprises a near-continuous gas composition time series, the quantification of diffuse CO2 gas flux, analytical results for direct samples of dry gas, seismic records, and GPS data. Gas emissions from the Krýsuvik geothermal system were exam…

Sedimentary dynamics and extensional structuring related to early Cretaceous rifting of Neocomian and Barremian deposits of the interior basin of Gab…

2008

18 pages; International audience; Recent field and subsurface data about the early Neocomian N'dombo series and the Neocomian to mid-Barremian Schistes series of the interior basin of Gabon further our understanding of the initial stages of early Cretaceous N40–60E extensional rifting. The syn-rift series comprise fluvial–lacustrine claystones–sandstones, rare conglomerates, and carbonates. The syn-rift fill begins with braided-stream feldspathic sandstones. These are overlain first by fluvial–lacustrine deposits and then by predominantly lacustrine–palustrine claystones, which are potential petroleum source rocks. The claystones are eroded in part and are capped by the pre-Aptian angular u…

On the origin of the southern Permian Basin, Central Europe.

2000

A detailed study of the structural and stratigraphic evolution of the Southern Permian Basin during latest Carboniferous to Early Jurassic times, supported by quantitative subsidence analyses and forward basin modelling for 25 wells, leads us to modify the conventional model for the Rotliegend-Zechstein development of this basin. The Late Permian-Early Jurassic tectonic subsidence curves are typical for a Permian to Early Triassic extensional stage that is followed by thermal subsidence. However, a purely extensional model is extremely problematic because active faulting during this time is 'minor' and generally hard to document. Using inverse techniques to model the subsidence curves, we q…

Ground motion phenomena in Caltanissetta (Italy) investigated by InSAR and geological data integration

2008

Urban areas are frequently affected by ground instabilities of various origins. The location of urban zones affected by ground instability phenomena is crucially important for hazard mitigation policies. Satellite-based Interferometric Synthetic Aperture Radar (InSAR) has demonstrated its remarkable capability to detect and quantify ground and building motion in urban areas, especially since the development of Advanced Differential Interferometric SAR techniques (A-DInSAR). In fact, the high density of re.ectors like buildings and infrastructures in urban areas improves the quality of the InSAR signal, allowing sub-centimetric displacements to be reliably detected. The A-DInSAR techniques a…

History of ancient megathrust earthquakes beneath metropolitan Tokyo inferred from coastal lowland deposits

2018

Abstract Metropolitan Tokyo is located directly above a subduction zone that has generated two megathrust earthquakes in the past 300 years. However, the timing of older megathrusts on this margin is poorly understood. In this study, we aim to constrain the timings of past megathrust earthquakes, using coastal stratigraphy, paleoecology, radiocarbon dating and archaeological records from coastal lowlands. An investigation of 13 boreholes in the southern coastal area of metropolitan Tokyo found evidence for 4 m of uplift in a 6000-year period. However, we found that net vertical displacement in the last 1000 years is approximately zero. Results suggest that preservation of usually ephemeral …

Regional Tectonic Setting and Geological Structure of the Rhenish Massif

1983

This chapter contains an outline of the geological history of the Rhenish Massif and the development of its margins and surrounding areas. Section 2.2 gives some main aspects of the development of the Variscan geosyncline and orogeny and a short description of the pre-Variscan geological history of this region. Since the end of the Variscan orogeny many different epeirogenetic processes have occurred here (Sect. 2.3). During these long geological times uplift and subsidence changed in the different parts of the Massif and in the surrounding areas.

Mesozoic discontinuities in the Panormide Carbonate Platform: constraints on the palaeogeography of the central Mediterranean

2008

Preservation of modern and mis 5.5 erosional landforms and biological structures as sea level markers: A matter of luck?

2021

The Mediterranean Basin is characterized by a significant variability in tectonic behaviour, ranging from subsidence to uplifting. However, those coastal areas considered to be tectonically stable show coastal landforms at elevations consistent with eustatic and isostatic sea level change models. In particular, geomorphological indicators—such as tidal notches or shore platforms—are often used to define the tectonic stability of the Mediterranean coasts. We present the results of swim surveys in nine rocky coastal sectors in the central Mediterranean Sea using the Geoswim approach. The entire route was covered in 22 days for a total distance of 158.5 km. All surveyed sites are considered to…