The March 11, 2002 Masafi, United Arab Emirates earthquake: Insights into the seismotectonics of the northern Oman Mountains   总被引：2，自引：1，他引：1  

Arthur Rodgers  Abdel-Rahman Fowler  Abdullah M.S. Al-Amri  Abdullah Al-Enezi 《Tectonophysics》2006,415(1-4):57-64

A moderate (M 5) earthquake struck the northeastern United Arab Emirates (UAE) and northern Oman on March 11, 2002. The event was felt over a wide area of the northern Emirates and was accompanied by smaller (felt) events before and after the March 11 main shock. The event was large enough to be detected and located by global networks at teleseismic distances. We estimated focal mechanism and depth from broadband complete regional waveform modeling. We report a normal mechanism with a slight right-lateral strike-slip component consistent with the large-scale tectonics. The normal component suggests relaxation of obducted crust of the Semail ophiolite (specifically, the Khor Fakkan Block) while the right-lateral strike-slip component of the mechanism is consistent with shear across the Oman Line. Felt earthquakes are rare in the region, however no regional seismic network exists in the UAE to determine local seismicity. This event offers a unique opportunity to study the active tectonics of the region as well as inform future studies of seismic hazard in the UAE and northern Oman.  相似文献   

Tectonic inheritance and kinematic strain localization as trigger for the formation of the Helvetic nappes,Switzerland     

Arthur Bauville  Stefan M. Schmalholz 《Swiss Journal of Geoscience》2017,110(2):523-534

The Helvetic nappes in Switzerland consist of sediments, which have been sheared off and thrust over the crystalline basement of the European passive continental margin during Alpine orogeny. Their basal shear zones usually root above the external crystalline massifs. However, the mechanisms that initiated the shear zones and the associated nappe formation are still debated. We perform two-dimensional numerical simulations of the shearing of linear viscous fluids above a linear viscous fluid with considerably higher viscosity (quasi-undeformable). The boundary between the fluid, mimicking the sediments, and the quasi-undeformable fluid, mimicking the basement, exhibits geometrical perturbations, mimicking half-grabens. These geometrical perturbations can trigger significant strain localization and the formation of shear zones within the linear viscous fluid although no rheological softening mechanism is active. This kinematic, ductile strain localization is caused by the half-grabens and the viscosity ratio between basement and sediments. The viscosity ratio has a strong control on the kinematics of strain localization, whereas the depth of the half-grabens has a weak control. For sediment viscosities in the order of 10²¹ Pas and typical half-graben geometries of 5 km depth and 25 km width the localization generates (a) low-angle shear zones at the basement-sediment interface, but also entirely within the sediments, (b) horizontal transport >10 km associated with the shear zones, (c) shear zones with thickness in the order of 100 m, (d) an ordered stacking of model nappes and (e) shear zones that root above the basement. The results suggest that tectonic inheritance in the form of half-grabens and associated kinematic strain localization could have been the triggering mechanism for Helvetic nappe formation, and not rheological softening mechanisms, which might, however, have subsequently further intensified shear localization significantly.  相似文献   

Multiple rainfall event pollution transport by sustainable drainage systems: the fate of fine sediment pollution     

D. Allen  S. Arthur  H. Haynes  V. Olive 《International Journal of Environmental Science and Technology》2017,14(3):639-652

A key design criterion of sustainable urban drainage systems is to mitigate urban stormwater pollution. Current research defines sustainable urban drainage systems (SuDS) pollutant treatment efficiency through the detention of total suspended solids, urban nutrients and heavy metal pollutants within the system during a design flow event, with research focusing on sand (>2 mm) sediment movement. The impact of multiple rainfall–runoff events on the fine sediment (<2 mm) treatment efficiency of SuDS is not yet well defined, and the temporal movement of detained sediment has not been investigated in detail. The field research presented in this paper addresses this research gap, monitoring ongoing fine sediment transport through a best-practice-designed SuDS network over 12 months through the use of a novel rare earth oxide trace methodology. Through time-stepped monitoring of the fine sediment pollution across three SuDS treatment trains (networks), the following key conclusions have been drawn. (1) That fine sediment becomes re-suspended and re-deposited within SuDS assets and the network as a result of ongoing multiple rainfall–runoff events. (2) That this re-suspension continues for over 52 weeks. (3) That by area, linear wetlands (within the monitored networks) outperform wetland and swale assets in multiple event fine sediment detention. And (4) that multiple event monitoring and analysis of fine sediment within a SuDS network highlights the under-performance of SuDS assets against current design event expectations.  相似文献   

Relationship between geoacoustic properties and chemical content of submarine polymetallic crusts from offshore Brazil     

Arthur Ayres Neto  Vanessa Alves da Costa  Clara Pinto Ferreira Maia Porto  Thais Cristina Vargas Garrido  Jean-Pierre Hermand 《Marine Georesources & Geotechnology》2020,38(4):437-449

Abstract

Marine mining is the ocean’s new exploration frontier, and polymetallic crusts (PMCs) and ferromanganese nodules are considered a strategic resource for the future. Acoustic geophysical methods are a valuable tool for oceanic research and have been employed for several decades in the exploration of marine resources and environmental evaluations. The main objective of this work was to investigate the correlation between the chemical composition of PMCs from three different areas along the Brazilian continental margin and their physico-acoustic attributes (P-wave velocity, density and acoustic impedance). The results show that the geoacoustic properties of PMCs are correlated to their chemical composition. Measurements showed positive and negative trends between acoustic impedance and studied elements (Fe, Mn, Co, Cu, Zn, W and Ni) according to the direction of measurement, indicting high anisotropy levels. Our study sheds initial light on the correlation between acoustic properties and metal content of PMCs. The study facilitates assessments of the acoustic responses of PMCs allowing more efficient prospection and exploitation compared to ship-board geophysical techniques that are too qualitative to identify PMCs. The results can contribute to determining the best procedures and techniques for more efficient future exploration of this resource.  相似文献