Co‐seismic deformation and post‐glacial slip rate along the Magallanes‐Fagnano fault,Tierra Del Fuego,Argentina     

Sandrine Roy  Riccardo Vassallo  Joseph Martinod  Matías C. Ghiglione  Christian Sue  Pascal Allemand 《地学学报》2020,32(1):1-10

Across the extreme south of Patagonia, the Magallanes‐Fagnano Fault (MFF) accommodates the left‐lateral relative motion between South America and Scotia plates. In this paper, we present an updated view of the geometry of the eastern portion of the MFF outcropping in Tierra del Fuego. We subdivide the MFF in eight segments on the basis of their deformation styles, using field mapping and interpretation of high‐resolution imagery. We quantify coseismic ruptures of the strongest recorded 1949, M_w7.5 earthquake, and determine its eastern termination. We recognize several co‐seismic offsets in man‐made features showing a sinistral shift up to 6.5 m, greater than previously estimated. Using ¹⁰Be cosmogenic nuclides depth profiles, we date a cumulated offset in post‐glacial morphologies and estimate the long‐term slip rate of the eastern MFF. We quantify a 6.4 ± 0.9 mm/a left‐lateral fault slip rate, which overlaps geodetic velocity and suggests stable fault behaviour since Pleistocene.  相似文献   

Sediment-charged flash floods on Montserrat: The influence of synchronous tephra fall and varying extent of vegetation damage     

Jan Alexander  Jenni Barclay  Janez Sušnik  Sue C. Loughlin  Richard A. Herd  Amii Darnell  Sian Crosweller 《Journal of Volcanology and Geothermal Research》2010

On 20th May 2006 the Soufrière Hills Volcano on the Caribbean island of Montserrat experienced a large dome collapse and intense rainfall generated flash floods. The floods had very high loads of volcanic debris derived both from this and previous eruptions and can thus be classified as lahars. The floods reached unusually high water levels and caused substantial geomorphic change in the Belham Valley. Detailed rainfall and geomorphological data, coupled with the precise timing of events and yewitness accounts have facilitated an assessment of the relative importance of rainfall volume and intensity, older volcanic debris, pre- and syn-flood tephra fall and the extent of pre-flood vegetation damage for the behavior of this and subsequent sediment-laden floods in this setting. The change in runoff behavior was controlled by preexisting vegetation damage and synchronous tephra fall and this was critically important in controlling the impact of these flash floods. Although rainfall intensity and volume have some control on flood occurrence they are not the critical control on flash flood impact on the geomorphology in the Belham Valley. A significant conclusion of this study is that the extreme nature of the flash floods was not caused by extreme rainfall (as is commonly believed to be the primary cause of flash floods) but rather it was the result of changed runoff behaviour caused by the widespread syn-flood tephra deposition and importantly the widespread vegetation damage by volcanic-associated acid rain in the preceding weeks.  相似文献   

A Genetic Algorithm Variational Approach to Data Assimilation and Application to Volcanic Emissions     

Kerrie?J.?Schmehl  Sue?Ellen?HauptEmail author  Michael?J.?Pavolonis 《Pure and Applied Geophysics》2012,169(3):519-537

Variational data assimilation methods optimize the match between an observed and a predicted field. These methods normally require information on error variances of both the analysis and the observations, which are sometimes difficult to obtain for transport and dispersion problems. Here, the variational problem is set up as a minimization problem that directly minimizes the root mean squared error of the difference between the observations and the prediction. In the context of atmospheric transport and dispersion, the solution of this optimization problem requires a robust technique. A genetic algorithm (GA) is used here for that solution, forming the GA-Variational (GA-Var) technique. The philosophy and formulation of the technique is described here. An advantage of the technique includes that it does not require observation or analysis error covariances nor information about any variables that are not directly assimilated. It can be employed in the context of either a forward assimilation problem or used to retrieve unknown source or meteorological information by solving the inverse problem. The details of the method are reviewed. As an example application, GA-Var is demonstrated for predicting the plume from a volcanic eruption. First the technique is employed to retrieve the unknown emission rate and the steering winds of the volcanic plume. Then that information is assimilated into a forward prediction of its transport and dispersion. Concentration data are derived from satellite data to determine the observed ash concentrations. A case study is made of the March 2009 eruption of Mount Redoubt in Alaska. The GA-Var technique is able to determine a wind speed and direction that matches the observations well and a reasonable emission rate.  相似文献   

Assessment of agricultural drought using a simple water balance model in the Free State Province of South Africa   总被引：1，自引：1，他引：0  

Mokhele Edmond Moeletsi  Sue Walker 《Theoretical and Applied Climatology》2012,108(3-4):425-450

Water Requirement Satisfaction Index (WRSI) at three different probability levels (20%, 50%, and 80%) was used to quantify drought affecting rain-fed maize production in the Free State Province of South Africa based on climate data from 227 weather stations. Results showed high spatial variability in the suitability of different areas: the southern and southwestern localities are unsuitable due to high drought incidences; the northern, central, and western regions are marginally suitable; the eastern, northerneastern areas and a few patches in the northwest are highly suitable with relatively low drought severity. Proper choice of maize varieties to suit conditions at different localities is crucial. The Mann–Kendall test and coefficient of variation were further used to determine trends and temporal variability, respectively, in the WRSI, seasonal rainfall, and seasonal maize water requirements. Results of this analysis revealed no significant positive trends in the WRSI, no significant negative trends in seasonal rainfall, and no significant positive trends in maize water requirements, contradicting previous findings of increased drought severity. Seasonal rainfall and the WRSI showed high interseasonal variability, while seasonal maize water requirements showed low variability. In view of these observations, it is apparent that realignment of management practices is an overdue prerequisite for sustainable maize production.  相似文献   

Active strike-slip faulting in the Chablais area (NW Alps) from earthquake focal mechanisms and relative locations     

Bastien Delacou  Nicholas Deichmann  Christian Sue  Fran?ois Thouvenot  Jean-Daniel Champagnac  Martin Burkhard 《Eclogae Geologicae Helvetiae》2005,98(2):189-199

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Hazard transformation and hazard management issues in the London megacity     

Dennis Parker  Sue Tapsell 《GeoJournal》1995,37(3):313-328

Megacities are likely to present the greatest future challenges for hazard management. In them increasingly complex societies are continually modifying responses to dynamic sets of external risks. Although most have proven resilient to past disasters, new types of threat are emerging. London — which is both the world's oldest megacity and one of its most resilient — has long experience of the transformation of hazards in time and space. Although not as hazard-prone as some megacities, this one is increasingly exposed to a wide range of interactive hazards. Here trends of flooding, air pollution and terrorism are discussed together with policy responses. London demonstrates that robust action can be successful in reducing high-intensity hazards but it also shows that contemporary management is characterised by top-down technological fixes whose long-term effectiveness is questionable. In general, anticipatory responses have been limited and present-day London has not capitalised on its rich legacy of successful experience in coping with hazard.  相似文献   

Sustaining agricultural production and food security in Southern Africa: an improved role for climate prediction?   总被引：1，自引：0，他引：1  

Emma Archer  Elijah Mukhala  Sue Walker  Maxx Dilley  Kennedy Masamvu 《Climatic change》2007,83(3):287-300

Livelihoods and household food security in the Southern African region can be extremely vulnerable to the negative effects of climate stress as shown by the 2002–2004 ‘complex emergency.’ Climate prediction may prove a valuable resource in mitigating these effects. If climate prediction is applied successfully, it may be able to help guide responses in populations at risk to reduce vulnerability to climate stress. The study presented here seeks to understand what would constitute an improved role for climate prediction in contributing to sustaining agricultural production and food security in Southern Africa. Investigation undertaken during the 2002/2003 rainy season under regional conditions of elevated disaster risk shows, however, that a number of weaknesses and gaps persistently characterize climate information systems in the Southern African region, and constrain such systems’ ability to benefit key sectors, particularly agriculture. The stakeholder identification of such gaps forms the basis for distilling concrete recommendations to improve process and organizational efficiency. Such recommendations, while developmental, should better enable institutions and stakeholders involved in climate prediction to fulfill their potential in supporting development of successful adaptation strategies in populations and sectors at risk.  相似文献   

Partial substitution of peat moss with biochar for sustainable cultivation of <Emphasis Type="Italic">Durio zibethinus L</Emphasis>. in nurseries     

Robert Thomas Bachmann  Sharifah Adawiyah  Thilagam Krishnan  Benson Khoo  Tan Sue Sian  Trevor Richards 《Arabian Journal of Geosciences》2018,11(15):426

The extensive use of peat moss as potting medium in nurseries worldwide is not sustainable causing peatland depletion and greenhouse gas emissions. This research seeks to explore whether wood biochar produced by the environment-friendly flame curtain method can partially substitute peat moss in plant nurseries without affecting plant growth and health. Biochar was produced from durian wood logs in a top-quenched Kon-Tiki earth kiln, crushed, and mixed with peat moss at dosages of 0, 1, 2.5 and 5% (w/w). Durian seedlings were grown in 2.5 L polybags arranged in randomised complete block design with 4 replicates per treatment. Plant height, collar diameter, pH, moisture content, number of branches and leaves, and plant health were monitored weekly for 94 days. Liquid fish fertiliser was used as organic fertiliser. Our results demonstrated that biochar can substitute at least 5% (w/w) peat moss without negatively affecting plant height, collar diameter, number of leaves and branches, and plant health. In addition, organic fertiliser is not required during the first 3 months of cultivation resulting in cost savings to the nursery operator. Plant height was found to be the most accurate yet simple monitoring parameter studied. A better understanding of the effect of higher biochar application rates as well as the number of times the potting medium can be reused without loss of potting medium properties and health can help to further cut nursery cost and reduce reliance on peat moss.  相似文献   

Lateglacial and Holocene relative sea‐level changes and first evidence for the Storegga tsunami in Sutherland,Scotland          下载免费PDF全文

Antony J. Long  Natasha L. M. Barlow  Sue Dawson  Jon Hill  James B. Innes  Catherine Kelham  Fraser D. Milne  Alastair Dawson 《第四纪科学杂志》2016,31(3):239-255

We reconstruct one of the longest relative sea‐level (RSL) records in north‐west Europe from the north coast of mainland Scotland, using data collected from three sites in Loch Eriboll (Sutherland) that we combine with other studies from the region. Following deglaciation, RSL fell from a Lateglacial highstand of +6?8 m OD (Ordnance Datum = ca. mean sea level) at ca. 15 k cal a BP to below present, then rose to an early Holocene highstand and remained at ca. +1 m OD between ca. 7 and 3 k cal a BP, before falling to present. We find no evidence for significant differential Holocene glacio‐isostatic adjustment between sites on the north‐west (Lochinver, Loch Laxford), north (Loch Eriboll) and north‐east (Wick) coast of mainland Scotland. This suggests that the region was rapidly deglaciated and there was little difference in ice loads across the region. From one site at the head of Loch Eriboll we report the most westerly sedimentary evidence for the early Holocene Storegga tsunami on the Scottish mainland. The presence of the Storegga tsunami in Loch Eriboll is predicted by a tsunami wave model, which suggests that the tsunami impacted the entire north coast of Scotland and probably also the Atlantic coastline of north‐west Scotland.

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A Web-based system enabling the integration,analysis, and 3D sub-surface visualization of groundwater monitoring data and geological models     

Jane Hunter  Charles Brooking  Lucy Reading  Sue Vink 《International Journal of Digital Earth》2016,9(2):197-214

The 3D Water Chemistry Atlas is an intuitive, open source, Web-based system that enables the three-dimensional (3D) sub-surface visualization of ground water monitoring data, overlaid on the local geological model (formation and aquifer strata). This paper firstly describes the results of evaluating existing virtual globe technologies, which led to the decision to use the Cesium open source WebGL Virtual Globe and Map Engine as the underlying platform. Next it describes the backend database and search, filtering, browse and analysis tools that were developed to enable users to interactively explore the groundwater monitoring data and interpret it spatially and temporally relative to the local geological formations and aquifers via the Cesium interface. The result is an integrated 3D visualization system that enables environmental managers and regulators to assess groundwater conditions, identify inconsistencies in the data, manage impacts and risks and make more informed decisions about coal seam gas extraction, waste water extraction, and water reuse.  相似文献