Relay ramps as pathways for turbidity currents: a study combining analogue sandbox experiments and numerical flow simulations     

WIEBKE ATHMER  REMCO M. GROENENBERG  STEFAN M. LUTHI  MARINUS E. DONSELAAR  DIMITRIOS SOKOUTIS  ERNST WILLINGSHOFER 《Sedimentology》2010,57(3):806-823

Unlike for subaerial settings, the impact of subaqueous relay ramps on sediment dispersal is still poorly understood. A combination of analogue laboratory experiments in a sandbox with numerical flow calculations is used to simulate relay ramp topographies on rifting continental margins and to analyse the resulting turbidity current pathways and their deposits. Various scenarios are investigated, including inflow perpendicular and oblique to the relay ramp axis as well as flow constrained by an incised channel on the ramp and by a landward‐directed tilt of the ramp. Without channelling, most sedimentation takes place on the basin floor because the bulk of the flow follows the steepest gradient down the fault and into the rift basin. With a channel along the relay ramp, significant flow occurs initially down the ramp axis, but channel spillover and basinward ramp tilting combine to redirect much of the sediment down the fault slope into the basin. When the relay ramp has a landward‐oriented tilt, most of the current flows down the ramp and deposits its sediment load there and at the foot of the ramp. However, also here a considerable amount of the flow is shed over the hanging wall fault and into the basin, forming a secondary depocentre, while ponding redistributes thin deposits over a wider area of the basin. The quantitative dependence of these results on the specific ramp geometries remains to be investigated further but may bear great importance for refined sedimentary models in subaqueous rifted settings as well as for hydrocarbon exploration therein.  相似文献   

Reconstruction of the paleo-coastline of Santorini island (Greece), after the 1613 BC volcanic eruption: A GIS-based quantitative methodology     

DIMITRIOS OIKONOMIDIS  KONSTANTINOS ALBANAKIS  SPYRIDON PAVLIDES  MICHAEL FYTIKAS 《Journal of Earth System Science》2016,125(1):1-11

A catastrophic volcanic explosion took place in Thera/Santorini island around 1613 BC, known as the ‘Minoan’ eruption. Many papers have dealt with the shape of the shoreline of the island before the eruption, but none with the shape of the shoreline exactly after it, assuming that it would be the same with the contemporary one. However, this is not correct due to the wave erosion. In this paper, a new DEM was constructed, covering both land and submarine morphology, then topographic sections were drawn around the island. Using these sections, the ‘missing parts’ (sea-wave erosion) were calculated, the shoreline was reconstructed as it was one day after the eruption and finally the erosion rate was calculated.  相似文献   

Use of artificial neural network for spatial rainfall analysis   总被引：1，自引：0，他引：1  

TSANGARATOS PARASKEVAS  ROZOS DIMITRIOS  BENARDOS ANDREAS 《Journal of Earth System Science》2014,123(3):457-465

In the present study, the precipitation data measured at 23 rain gauge stations over the Achaia County, Greece, were used to estimate the spatial distribution of the mean annual precipitation values over a specific catchment area. The objective of this work was achieved by programming an Artificial Neural Network (ANN) that uses the feed-forward back-propagation algorithm as an alternative interpolating technique. A Geographic Information System (GIS) was utilized to process the data derived by the ANN and to create a continuous surface that represented the spatial mean annual precipitation distribution. The ANN introduced an optimization procedure that was implemented during training, adjusting the hidden number of neurons and the convergence of the ANN in order to select the best network architecture. The performance of the ANN was evaluated using three standard statistical evaluation criteria applied to the study area and showed good performance. The outcomes were also compared with the results obtained from a previous study in the area of research which used a linear regression analysis for the estimation of the mean annual precipitation values giving more accurate results. The information and knowledge gained from the present study could improve the accuracy of analysis concerning hydrology and hydrogeological models, ground water studies, flood related applications and climate analysis studies.  相似文献