Shorelines

1] The Maldives experience seasonal shifts in monsoon winds from the west-northwest to northeast. The morphologic response of reef island beaches and shorelines to these predictable shifts in climate was examined on eight islands in South Maalhosmadulu Atoll based on global positioning system surveys of island shoreline planform in January and June 2002 and February 2003. Surveys show that islands exhibit large gross changes (31-120% of beach area) in shoreline position between seasons. Such changes reflect large reversals in sediment flux of 9-23 Â 10 3 m 3 on a biannual basis driven by seasonal reversals in wind and wave conditions. Annual net change is small (2-15%), suggesting islands spatially exhibit a dynamic equilibrium. An island oscillation index (I o ) is defined that describes the spatial extent of shoreline change around islands. Island shape (ellipticity, e) is found to be positively correlated with I o in the expression I o = 1.021e À 0.275, suggesting island shape is a better indicator of the susceptibility of island shorelines to morphological change than wave energy exposure.

High rates of coastal retreat characterise the weakly cemented Plio-Pleistocene rocks and sediments which form much of the cliffed coastline of East Anglia, southern North Sea. The accurate establishment of sediment losses from these cliffs has a regional significance as these sediments are important in maintaining beaches and nearshore bank systems and in feeding nearshore sediment transport pathways. However, the high spatial and temporal variability of cliff failure processes in such materials necessitates fine-scale integration of alongshore variations in cliff retreat over a series of well-established time periods to accurately define cliffline recession rates and sediment volume inputs to the nearshore system. This study applied the DSAS (Digital Shoreline Analysis System) within the GIS software package ArcMap to digitised, georeferenced positions of former shorelines, obtained from historic maps and aerial photographs (after 1992), for the sections of Benacre-Southwold and Dunwich-Minsmere on the Suffolk coast of East Anglia, UK; transects were cast every 10 m alongshore, producing very high spatial resolution upon which to assess shoreline retreat (over 1000 transects along 11 km of shoreline). Long-term (1883-2008) mean shoreline retreat rates varied between 2.3-3.5 m a-1 (Benacre-Southwold) and 0.9 m a-1 (Dunwich-Minsmere). For six cliffed subunits within these larger coastal sections, spatial variations in cliffline recession rates for shorter time intervals (at ca. 20-year intervals) within this longer (125 year) period were established. The combination of recession rates with photogrammetric methods of obtaining cliff top elevation at the same spatial resolution, available using aerial photographs and digital terrain models, along with cliff sediment composition, allowed the calculation of sediment volumetric inputs from cliff retreat in the period 1992-2008. Re-assessment of the magnitude and location of sediment inputs into the nearshore zone, their interaction with regional sediment transport and the growth of inshore bank systems, as well as the implications for contemporary and near-future coastal management strategies are discussed with reference to this section of the Suffolk coast. Temporal and spatial variations in recession rates and sediment release from soft rock cliffs,

The Regional Ocean Modeling System (ROMS) is used to systematically investigate equilibrium conditions and seasonal variations of the Benguela system at a resolution of 9 km, including both the large-scale offshore flow regime and the economically and ecologically important coastal upwelling regime. A shelf-edge poleward flow exists in the northern Benguela region (i.e., north of ∼28°S) and is driven primarily by the wind stress curl via the Sverdrup relation. As such, it is strongly seasonal and is most intense during spring and summer, when the wind stress curl is most negative. The poleward flow deepens as it moves southward; between ∼25° and 27°S, much of it veers offshore because of the nature of the wind stress curl and its interaction with the northwestward path of the Benguela Current, which is influenced by alongshore topographical variations. The Benguela Current is driven by nonlinear interactions of passing Agulhas rings and eddies and does not have a striking seasonal s...

Between Point Grenville, Washington, and Point Conception, California (1500 km distance) 21 dune fields record longshore transport in 20 littoral cells during the late Holocene. The direction of predominant littoral transport is established by relative positions of dune fields (north, central, or south) in 17 representative littoral cells. Dune field position is north of cell midpoints in northernmost Oregon and Washington, but is south of cell midpoints in southern Oregon and California. Downdrift sand trapping occurs at significant changes in shoreline angle and/or at bounding headlands that project at least 2.5 km seaward from the general coastal trend. Sand bypassing occurs around small headlands of less than 0.5 km in projection distance. A northward shift of the winter low-pressure center in the northeast Pacific Ocean is modeled from 11 ka to 0 ka. Nearshore current forcing in southern Oregon and northern California switched from northward in earliest Holocene time to southward in late Holocene time. The late Holocene (5-0 ka) is generally characterized by net northward littoral drift in northernmost Oregon and Washington and by net southward littoral drift in southernmost Oregon and California. A regional divergence of net transport direction in central Oregon, i.e. no net drift, is consistent with modeled wind and wave forcing at the present time (0 ka).

This paper reviews historical methods for estimating surge hazards and concludes that the class of solutions produced with Joint Probability Method (JPM) solutions provides a much more stable estimate of hazard levels than alternative methods. We proceed to describe changes in our understanding of the winds in hurricanes approaching a coast and the physics of surge generation that have required recent modifications to procedures utilized in earlier JPM studies. Of critical importance to the accuracy of hazard estimates is the ability to maintain a high level of fidelity in the numerical simulations while allowing for a sufficient number of simulations to populate the joint probability matrices for the surges. To accomplish this, it is important to maximize the information content in the sample storm set to be simulated. This paper introduces the fundamentals of a method based on the functional specification of the surge response for this purpose, along with an example of its application in the New Orleans area. A companion paper in this special issue ) provides details of the portion of this new method related to interpolating/extrapolating along spatial dimensions.

Una de las principales amenazas a las cuales está expuesta la franja costera ecuatoriana son los tsunamis, en atención a los escenarios de desastre que pudieran ocasionar. Para el caso ecuatoriano, las probabilidades de ocurrencia de tsunamis están muy ligadas a la sismicidad, determinada principalmente por un marco tectónico correspondiente a un límite de placas de convergencia (subducción); sin embargo, tsunamis ocurridos en otras localidades distantes de la cuenca del océano Pacífico, han hecho sentir sus efectos en costas ecuatorianas. En vista de ello, es importante evaluar la vulnerabilidad de la geomorfología costera de la provincia Manabí ante la ocurrencia de tsunamis, en términos de la protección que el relieve puede representar para algunos sectores y, de la exposición al barrido de las olas o al fortalecimiento de éstas, que puede significar para otros sectores. La metodología de trabajo ha considerado la sectorización de la costa manabita, para lo cual se han identificado y caracterizado áreas con disponibilidad de sedimentos a partir de la línea de costa (naturaleza de los ambientes depositacionales), ambientes o unidades geomorfológicas (formas de relieve) asociadas a la sedimentación y a la erosión, altitudes del relieve de colinas, lomas y acantilados, morfología de la línea de costa, morfología del fondo marino, dimensiones de la plataforma continental y vegetación. Esta información se levantó a partir de la observación, análisis e interpretación de imágenes satelitales de Google Earth y, de los mapas de relieve de Google Maps. Una primera aproximación, ha permitido definir siete sectores a lo largo del margen costero de Manabí: Cojimíes – Pedernales, Pedernales – Jama, Jama – Canoa, Canoa – San Jacinto, San Jacinto – San Lorenzo, San Lorenzo – Puerto Cayo, Puerto Cayo – Ayampe, para los cuales se discuten sus niveles de vulnerabilidad geomorfológica, siendo los sectores más susceptibles Cojimíes – Pedernales, Canoa – San Jacinto y San Jacinto – San Lorenzo, condicionados principalmente por la presencia de formas de relieve bajas, de topografía llana y escasa pendiente.

The viscosity of pantelleritic melts from the Khaggiar lava flow (5.5 ka -Pantelleria Island) was investigated as a function of temperature and water content. High (1673-1323 K) and low (973-613 K) temperature dry and hydrous liquid viscosities were determined by a combination of concentric cylinder (10 2.44 to 10 4.56 Pa s) and micropenetration (10 8.67 to 10 11.37 ) viscometric techniques. The effect of water, from 0.02 to 3.55 wt.% H 2 O, was explored in the temperature range of 973-613 K. Liquid viscosities have been parameterized by means of a modified Vogel-Fulcher-Tammann equation (VFT) which describes viscosities and derivative properties (glass transition temperature T g , fragility m) of silicic liquids as a function of T-X (H 2 O). The results yield the expected strong decrease of viscosity with temperature and water content. Fragility, as a measure of the deviation from Arrhenian behavior, increases with H 2 O content from m =23 to m = 28. The peralkalinity (molar alkali excess over alumina), which characterizes the pantelleritic magmas, exerts a primary control over the rheological behavior of these melts. The excess of alkalies over alumina content is responsible for the peculiarly low viscosities of pantelleritic liquids compared to their metaluminous counterpart in the high temperature range, and leads to an even more dramatic decrease in the viscosities of these rhyolites in the low temperature range. Comparison with available models shows substantial differences between the measured and calculated viscosities. Based on our new viscosity results combined with existing literature data, we propose a new parameterization based on a modified Vogel-Fulcher-Tammann equation, accounting for the effect of water and composition, which can be used to determine the viscosity of pantelleritic melts. The derived relationship reproduces the experimental data (58 in total) in the viscosity range from 10 2.44 to 10 11.37 Pa s and in the temperature range from 613 to 1673 K within a root-mean-square-error (RMSE) of 0.12 log units. Application of this calculation model for high temperature low viscosity hydrous melt is limited by the lack of experimental data and needs verification by additional measurements. Volcanological implications for welding and rheomorphic processes as well as conduit dynamic modeling are also discussed in light of the results presented in this work.

This contribution describes the development, calibration and verification of a 1-D behaviour-orientated shoreline prediction model. The model primarily encapsulates shoreline displacement forced by wave-driven cross-shore sediment transport. Hysteresis effects are shown to be important and are included in the model, whereby present shoreline change is influenced by past hydro-/morpho-dynamic conditions. The potential magnitude of shoreline change increases with incident wave power and the degree of disequilibrium. The latter disequilibrium term (Ω eq − Ω) is expressed in terms of the time-evolving equilibrium (Ω eq ) and instantaneous (Ω) dimensionless fall velocities and dictates the direction of shoreline movement. Following the equilibrium fall velocity is defined as a function of the weighted antecedent conditions and is a proxy for the evolving beach state. The decay rate of the weighting function used to compute Ω eq is a model free parameter determined by calibration against measured data, which physically reflects the degree of observed 'memory' of the system. The decay in amplitude of this weighting function with time is controlled by a 'memory decay' term (ϕ), where the weighting reaches 10%, 1% and 0.1% at ϕ, 2ϕ and 3ϕ days prior to the current calculation time. The model is applied to two multi-year (6+ years) data sets incorporating hourly wave and weekly shoreline measurements, from two contrasting energetic sites in SE Australia. The first is the relatively dissipative, straight Gold Coast (QLD) and the second is a more intermediate embayed beach at Narrabeen (NSW). The model shows significant skill at hindcasting shoreline change at both sites, predicting approximately 60% of the total shoreline variability. The Gold Coast shoreline is dominated by a strong seasonal signal. Conversely, at the Narrabeen embayment, shoreline variability (and morphology) is more dynamic, responding at storm frequency. Evidence suggests that there is a strong coherence between the shoreline position and morphodynamic state and that both have response times characterised by ϕ. It is hypothesised that optimised ϕ values in the shoreline model physically relate to the efficiency of sediment exchanges between the shoreface and offshore bars and the prevalence of one-or two-dimensional horizontal circulation. The general success of this new shoreline model for hindcasting the observed shoreline behaviour at two distinctly different open-coast sites suggests that this approach may be suitable for broader application.

, and the origin of unconformity-bounded depositional sequences. Mar. Geol., 97: 35-56. Unconformity-bounded depositional sequences represent the fundamental building blocks of sedimentary successions. They are typically characterized by onlap at the base and by offlap at the top, and they tend to be markedly asymmetrical, with onlap accounting for a larger part of any cycle of sedimentation than offlap. Offlap cannot be attributed solely to erosional truncation, but instead implies that sequence boundaries develop over a finite interval of time. Depositional sequences are commonly associated with a cyclic arrangement of facies, but transgressive-regressive cycles are out of phase with respect to sequence boundaries, which in down-dip locations are both overlain and underlain by progradational deposits, and hence form during times of regression of the shoreline. These observations are used to develop some ideas about the origin of unconformity-bounded sequences, with reference to the inter-related roles of changes in depositional base level and sediment supply. In particular, it is shown than onlap and offlap are due to lateral migration of a "line of critical bypassing", defined so as to incorporate the effects of sediment loading and compaction as well as the rate of change of elevation with respect to sea level. Downward shifts in onlap may be achieved by either an increase in the rate of eustatic fall or a decrease in the rate of tectonic subsidence, and it is premature to assume that eustatic and tectonic controls on sea level may be distinguished solely on the basis of the frequency of depositional cyclicity. Small shifts in the position of onlap can also be produced by changes in sediment supply, and more attention needs to be paid to the influence of sediment supply in the development of minor boundaries. Unconformities related to eustatic fluctuations are thought to correspond approximately to times of relatively rapid sea-level fall (inflection points), but questions remain about the existence of possible leads and lags of up to ~ cycle, and hence about the degree to which sequence boundaries of eustatic origin may vary in age both within a given basin and from one basin to another.

Landsat Enhanced Thematic Mapper imagery (ETM) of 2002 and aerial photography of 1955, combined with published charts and field observations were used to interpret geomorphological changes in the coastal zone between Kitchener drain and Damietta spit in the northeastern Nile delta previously recognized as a vulnerable zone to the effects of any sea-level rise resulting from global warming. The interpretation resulted in recognition of several changes in nine identified geomorphological land types: beach and coastal flat, coastal dunes, agricultural deltaic land, sabkhas, fish farms, Manzala lagoon, saltpans, marshes and urban centers. Reclamation of vast areas of the coastal dunes and of Manzala lagoon added about 420 km 2 to the agricultural deltaic land. About 48 km 2 of sand dunes, marshes, sabkhas and salt pans have been converted to productive fish farms. The main urban centers have expanded, and new urban centers (Damietta harbor and the New Damietta city) have been constructed at the expense of vast areas of Manzala lagoon, coastal dunes, and backshore flats. As the consequence of human activities the size of Manzala lagoon has been reduced to less than 50%. Short-term shoreline changes along the coast of the study area established from beach profile survey, spanning the years of 1990 to 2000, reveal longshore patterns of erosion versus accretion. The rate of shoreline retreat has increased in the downdrift side of Damietta harbor (- 14 m/year), whereas areas of accretion exist within the embayment of Gamasa and in the shadow of Ras El Bar detached breakwater system, with a maximum shoreline advance of ~ 15 m/year. A sandy spit, 12 km long, has developed southeast of Damietta promontory. These erosion/accretion patterns denote the natural processes of wave-induced longshore currents and sediment transport, in addition, the impact of man-made coastal protection structures.

Coastal vulnerability in barrier island systems is extremely high. The barrier island shoreline is exposed to many threats, such as storm erosion, reductions in sediment longshore drift and sea level rise. Many of these threats to coastal areas, such as Ria Formosa, are likely to increase in the near future. The main objectives of the present study are to identify the areas in the system that are at most risk by assessing the evolution of the Ria Formosa barrier island system since the 1940s, and determine which interventions would be necessary to protect these areas.

Throughout the history, public spaces of Istanbul were developed near the seashores. By the end of the 20th century Istanbul's relation with the sea was severed by new transformations. Especially the Coastal Line Project, which was designed as a part of developmentalist policies at the 20 th century, has blocked the relation between the land and the sea. In this study the coastline of Bosphorus between the two bridges will be examined by analyzing different sections at different districts. Especially cul-de-sacs (blind alleys), landfill areas and highways ending up at or opening to the Bosphorus, will be documented. It is aimed to create a new map of the Bosphorus exploring the new linkages between sea and land. The study will generate useful design proposals on urban fabric and coastal land uses by focusing on the vital locations in terms of accessibility to water. As a result, new interventions to link the sea with the land and to improve the everyday life of the city will be proposed, in order to reconfigure the relationship between the city and water.

This paper presents an evaluation of Formal Safety Assessment framework for cargo ships at coasts and open seas of Turkey. Based on Turkish Under secretariat of Maritime Affairs casualty reports, this study identifies risk factors that have significant, independent effects upon the likelihood of ship and offshore operations. A case study is carried out to determine the most common causes of unintentional damages on cargo ships using FSA. It is obvious that shortage of skilled crew and crew training become very important for safety. This would require a compulsory course related to the human functions such as knowledge of regulations and use of equipment. Finally, some conclusions and suggestions are drawn concerning the needs to reduce the risks and to improve certain safety measures at coasts and open seas of Turkey.

A numerical method for non-hydrostatic, free-surface, irrotational flow governed by the nonlinear shallow water equations including the effects of vertical acceleration is presented at the aim of studying surf zone phenomena. A vertical boundary-fitted grid is used with the water depth divided into a number of layers. A compact finite difference scheme is employed for accurate computation of frequency dispersion requiring a limited vertical resolution and hence, capable of predicting the onset of wave breaking. A novel wet-dry algorithm is applied for a proper handling of moving shoreline. Mass and momentum are strictly conserved at discrete level while the method only dissipates energy in the case of wave breaking. The numerical results are verified with a number of tests and show that the proposed model using two layers without ad-hoc assumptions enables to resolve propagating nonlinear shoaling, breaking waves and wave run-up within the surf and swash zones in an efficient manner.

"This thesis has had its focus on ceramic shards found in a trench by the late neolithic western shore of the Ajvide site. The purpose of the thesis is to investigate if there are changes in the pottery between the test trench and the ceramics found by the graves, known as the main site. The author has compared the ornaments from the test trench with an ornament schedule made from over 50 000 shards from the assumed main site. Not only changes regarding ornaments has been noticed but also new techniques and raw material. The author has also implemented two 14Cdatings which backs his hypothesis that the shards from the test trench are younger than the shards that made the earlier ornament schedule. According to the author, due to cultural changes, he is of the opinion that some of the examined shards represent ceramics from a hybrid culture consisting material and ritual traits from the pitted ware culture and the battleaxe (boataxe) culture."

The aim of this study is to provide new data on relative sea-level changes and neotectonics of the northeastern Aegean Sea region (Eastern Mediterranean) through the analysis of the coastal geomorphology of Lesvos, the third largest Greek island. There is a paucity of presently available data in this sector of the Aegean Sea, which is a tectonically active area strongly controlled by the North Anatolian Fault. In this paper, morphological, biological and sedimentary records of paleo-sea levels have been used to reconstruct relative sea-level changes, to identify variations in the tectonic regimes as well as to assess the paleoseismicity in the studied areas. According to the results, late Quaternary relative sea-level changes at Lesvos were not homogenous and variations in the tectonic setting played a crucial role in the coastal evolution. The NW-SE trending faults on the southern shore of the island control a significant uplift affecting about 30 km of coastline. This uplift trend is controlled by the footwall of the Lesvos Fault, a major offshore normal fault that has been subject to relatively little quantitative investigation. Radiocarbon dating indicated that the last co-seismic uplift took place at 3365-3963 cal yr BP and resulted in about 0.75 m of vertical displacement. In contrast, all the paleo-sea-level markers mapped in the northeastern sector were presently underwater and, despite the high seismicity of the area, no evidence of coastal uplift was observed in this part of the island. Thus, the paper provides the first field evidence of a differential late Quaternary evolution of Lesvos Island. In addition, results represent the first quantitative information on the activity of the Lesvos Fault, suggesting a reconsideration of its importance in the neotectonics of the area.

The Eocene Sant Llorenç del Munt fan-delta complex lies on the southeastern edge of the Ebro Basin in NE Spain. Alluvial fans and fan deltas prograded northwestwards from the Catalan Coastal Range to form a series of clastic wedges that were interrupted by marine transgressions of period varying from 60,000 to a few hundred years, resulting in a highly cyclic succession. The cyclicity of the succession was controlled by a combination of syndepositional basin-margin tectonics, high sediment supply, and eustatic sea-level changes.

Morphostratigraphic and sedimentological studies were undertaken in the Cap Bon peninsula, north-eastern Tunisia. These studies have identified a series of middle to late Pleistocene–age marine deposits discontinuously cropping out on three raised platforms (Pf I, Pf II and Pf III). These stepped marine platforms (terraces) were related to the interplay between Pleistocene sea-level changes and progressive uplift movement during Quaternary period. We present here a description of facies organization and stratigraphic characteristics of the platform deposits, and their relation with eustatic and climatic variations. All the marine platforms unconformably overlie a Mio-Pliocene and Quaternary slope succession. The sedimentary sequences represented by mixed carbonate and siliciclastic bodies are related to the succession of highstand shorelines and contrasting climate conditions. The intercalated soils and calcretization occurred during episodes of relative sea-level fall. The oldest platforms (Pf I and Pf II), found at an elevation of about + 100 m and + 60 m respectively, have so far no equivalent in the northern, in the eastern or in the southern coasts of Tunisia. They are correspondingly attributed to MIS 11/13 and MIS 9/11. The youngest and lowest platform (Pf III) attains an altitude of + 40 m and shows three high-frequency cycles of sea-level rise and fall, probably associated with Marine Isotope Stage (MIS) 5e and MIS 7.

The tsunami waves generated during the Sumatra-Andaman earthquake of 26 December 2004 devastated the coastal area along Trinkat Island, causing sudden changes to the morphology of the landforms. This study uses a series of satellite images to record the short-term morphological response and shoreline changes as well as the recovery of coastal land after its destruction. Results indicate that the island experienced substantial erosion and a significant reduction in land area. Shoreline erosion is more prevalent than accretion at an average linear regression rate of ∼−9 m per year between 2004 and 2013. The major morphological changes at Trinkat Island were observed in coastal inlets, beaches, and bay head-lands. Straight beaches had almost recovered eight years after the tsunami; however, erosion is continually observed in other areas. Our study will help understanding the response and recovery of shorelines in Indian Ocean regions after the 2004 tsunami.

Differentiation of natural process units is promoted as a means of better understanding the interconnected nature of coastal systems at various scales. This paper presents a new holistic methodology for the identification of littoral cells. Testing is undertaken through application to an extensive region of central southern England. Diverse sources of information are compiled to map 8. detailed series of local sediment circulations both at the shoreline and in the offshore zone. Cells and sub-cells are subsequently defined by thorough examination of the continuity of sediment transport pathways and by identification of boundaries where there are discontinuities. Important distinctions are made between the nature and stability of different boundaries and a classification of types is devised. Application of sediment budget analysis to major process units helps to clarify the regional significance of different sediment sources, stores and sinks. Within the study area, it is shown that sediments circulate from distinct eroding cliff sources to well defined sinks. Natural beaches are transient and dependent upon the continued functioning of supply pathways from cliff sources. Relict cells with residual circulations are identified as a consequence of interference. Littoral cell boundaries separate independent coastal units from those that are partially, or totally dependent 80 the spatial impacts of various processes and practices can be discerned. They identify appropriate units for management, from which new cooperative groupings of local authorities can develop.

A methodology was developed to reconstruct the Roman topography and environmental features of the Sarno River plain, Italy, before the AD 79 eruption of the Somma–Vesuvius volcanic complex. We collected, localized and digitized more than 1800 core drilling data to gain a representative network of stratigraphical information covering the entire plain. Besides other stratigraphical data including the characteristics of the
pre-AD 79 stratum, the depth to the pre-AD 79 surface was identified from the available drilling documentations. Instead of a simple interpolation method, we used a machine based learning approach based on classification and regression trees to reconstruct the pre-AD 79 topography. We hypothesize that
the present-day topography reflects the ancient topography and related surface processes, because volcanic deposits from the AD 79 eruption coated the ancient landscape. Thus, ancient physiographic elements of the Sarno River plain are still recognizable in the present-day topography. Therefore, a high-resolution, present-day digital elevation model (DEM) was generated. A detailed terrain analysis yielded 15 different primary
and secondary topographic indices. Subsequently, a classification and regression model was applied to predict the depth of the pre-AD 79 surface combining present-day topographic indices with other physiographic data. This model was calibrated with the measured depth of the pre-AD 79 surface. The resulting pre-AD 79 DEM was compared with the classified characteristic of the pre-AD 79 stratum, identified from the drilling documentations. This allowed the reconstruction of pre-AD 79 environmental features of the Sarno River plain such as the ancient coastline, the paleo-course of the Sarno River and its floodplain.
To the knowledge of the authors, it is the first time that the pre-AD 79 topography of the Sarno River plain was systematically reconstructed using a detailed database and sophisticated data mining technologies.

Keywords: phreatomagmatic tuff ring tuff cone maar volcanic island basalt rift scoria sideromelane accretionary lapilli base surge Ambae Island is a mafic stratovolcano located in the northern Vanuatu volcanic arc and has a NE-SW riftcontrolled elongated shape. Several hundred scoria cones and fissure-fed lava fields occur along its long axis. After many decades of quiescence, Ambae Island erupted on the 28th of November 2005, disrupting the lives of its 10,000 inhabitants. Its activity remained focused at the central (crater-lake filled) vent and this is where hazard-assessments were focused. These assessments initially neglected that maars, tephra cones and rings occur at each tip of the island where the eruptive activity occurred b 500 and b 300 yr B.P. The products of this explosive phreatomagmatic activity are located where the rift axis meets the sea. At the NE edge of the island five tephra rings occur, each comparable in size to those on the summit of Ambae. Along the NE coastline, a near-continuous cliff section exposes an up to 25 m thick succession of near-vent phreatomagmatic tephra units derived from closely spaced vents. This can be subdivided into two major lithofacies associations. The first association represents when the locus of explosions was below sea level and comprises matrixsupported, massive to weakly stratified beds of coarse ash and lapilli. These are dominant in the lowermost part of the sequence and commonly contain coral fragments, indicating that the loci of explosion were located within a reef or coral sediment near the syn-eruptive shoreline. The second type indicate more stable vent conditions and rapidly repeating explosions of high intensity, producing fine-grained tephra with undulatory bedding and cross-lamination as well as megaripple bedforms. These surge and fall beds are more common in the uppermost part of the succession and form a few-m-thick pile. An older tephra succession of similar character occurs below, and buried trees in growth position, as well as those flattened within base surge beds. This implies that the centre of this eruption was very near the coastline. The processes implied by these deposits are amongst the most violent forms of volcanism on this island. In addition, the lowland and coastal areas affected by these events are the most heavily populated. This circumstance is mirrored on many similar volcanic islands, including the nearby SW Pacific examples of Taveuni (Fiji), Upolu and Savai'i (Samoa), and Ambrym (Vanuatu). These locations are paradoxically often considered safe areas during summit/central-vent eruptions, simply because they are farthest from the central sources of ash-fall and lahar hazard. The observations presented here necessitate a revision of this view.

La végétation et le climat du sillon sud rifain au Miocène supérieur sont très peu connus. Pour résoudre ce problème, sept coupes datées avec précision par les foraminifères planctoniques du Tortonien moyen à supérieur au Messinien ont été analysées tout au long du corridor sud rifain. Deux sont présentées ici. Le contenu en grain de pollen de ces coupes a permis la reconstitution du paysage végétal et du climat à cette basse latitude méditerranéenne. La mangrove à Avicennia occupait le littoral et une végétation herbacée subdésertique s'étendait à basse altitude. Des milieux forestiers se développaient en moyenne altitude. Le climat était tropical à subtropical, très sec sur le littoral mais plus humide en altitude. Le rapport Poaceae/Asteraceae a permis de montrer que la région du corridor sud rifain était devenue légèrement plus sèche encore au Messinien inférieur. Ces résultats confirment que le climat était chaud et sec bien avant la crise de salinité messinienne.

La erosión litoral y su consecuente retroceso de la línea de costa, representan una de las principales amenazas para los asentamientos poblacionales e infraestructuras ubicadas en diversos sectores del margen costero ecuatoriano. En este trabajo, en particular, se analiza el caso de la provincia Santa Elena, para lo cual se caracterizaron varios sectores de acantilados bajo criterios físicos, biológicos y de intervención antrópica, considerando a estas formas de relieve como indicadores y/o marcadores geomorfológicos de retroceso de la línea de costa. La metodología contempló (a) la sectorización del perfil costero con presencia de acantilados, basada en criterios geológicos, geomorfológicos y topográficos; (b) análisis de las magnitudes y regímenes de mareas y oleaje en el área de estudio; (c) cuantificación de la evolución de la línea de costa durante el período 2006-2020; (d) construcción de los perfiles evolutivos de los distintos sectores de línea de costa; (e) construcción de perfiles topográficos transversales de los acantilados prototipos de cada sector; (f) levantamiento de información en campo referida a parámetros geológicos, geomorfológicos, topográficos, hidrodinámicos, biológicos y antrópicos; y (g) tomas de imágenes ortogonales y oblicuas de los sectores de acantilados. Los resultados indican que, en efecto, el retroceso diferencial entre los distintos sectores de acantilados, es el resultado de la conjugación de factores físicos (litología, estructuras de los afloramientos rocosos, pendiente topográfica y morfodinámica) y antrópicos (obras de estabilización o prácticas ingenieriles inadecuadas). Los acantilados con mayor susceptibilidad a la erosión, son los modelados sobre el Grupo Ancón (turbiditas y lutitas), no obstante, la intervención antrópica en este sector, ha contribuido a minimizar los efectos erosivos debido a obras de estabilización; mientras que, los acantilados con una menor susceptibilidad relativa a los procesos erosivos, corresponden a aquellos desarrollados sobre las formaciones Zapotal (conglomerados, areniscas tobáceas y lutitas) y Angostura (coquinas, areniscas y lodolitas).

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. ?SW@ @ 5@ -?--ABSTRACT MOON, V.G. and HEALY, T., 1994. Mechanisms of coastal cliff retreat and hazard zone delineation in soft flysch deposits. Journal of Coastal Research, 10(3), 663-680. Fort Lauderdale (Florida), ISSN 0749-0208.

The Lake Lahontan basin has been the site of numerous pluvial lakes during the Pleistocene. We address the question of whether or not the highest remnant shoreline features around the perimeter of the lake were produced during the most recent Ž . Ž . Sehoo highstand ; 13 ka , the penultimate Eetza highstand ; 140-280 ka , or both. To do so, we document surficial characteristics, morphologic preservation, and soil development on multiple Sehoo beach barriers in the Jessup embayment to define the range in characteristics displayed by latest Pleistocene beach features. Sehoo barriers generally exhibit original constructional morphology that has been little modified by erosion. Soils developed on Sehoo barriers are generally thin and weakly developed and are strongly influenced by the introduction of eolian fines into the predominately clast-supported coarse beach gravels. Similar observations from 13 other highstand barriers and from seven older-than-latest Pleistocene paleosols located around the basin form the basis for a regional comparison. Based on similar characteristics, including the degree of morphologic preservation and weak soil development, we conclude that the widespread and nearly continuous high shoreline around the perimeter of Lake Lahontan dates from the most recent major lake cycle in all areas except in the Walker Lake subbasin. In the Walker Lake subbasin, isolated early to middle Pleistocene lacustrine outcrops and landforms are elevated as much as 70 m above the late Pleistocene limit, but are differentiated by their degraded form and lack of continuity around the subbasin. Similar unambiguous landforms were not observed elsewhere and at similar elevations in the northern subbasins of Lake Lahontan. q

The scale of groundwater upwelling on Mars, as well as its relation to sedimentary systems, remains an ongoing debate. Several deep craters (basins) in the northern equatorial regions show compelling signs that large amounts of water once existed on Mars at a planet-wide scale. The presence of water-formed features, including fluvial Gilbert and sapping deltas fed by sapping valleys, constitute strong evidence of groundwater upwelling resulting in long term standing bodies of water inside the basins. Terrestrial field evidence shows that sapping valleys can occur in basalt bedrock and not only in unconsolidated sediments. A hypothesis that considers the elevation differences between the observed morphologies and the assumed basal groundwater level is presented and described as the "dike-confined water" model, already present on Earth and introduced for the first time in the Martian geological literature. Only the deepest basins considered in this study, those with bases deeper than −4000 m in elevation below the Mars datum, intercepted the water-saturated zone and exhibit evidence of groundwater fluctuations. The discovery of these groundwater discharge sites on a planet-wide scale strongly suggests a link between the putative Martian ocean and various configurations of sedimentary deposits that were formed as a result of groundwater fluctuations during the Hesperian period. This newly recognized evidence of water-formed features significantly increases the chance that biosignatures could be buried in the sediment. These deep basins (groundwater-fed lakes) will be of interest to future exploration missions as they might provide evidence of geological conditions suitable for life. Plain Language Summary Most previous studies on Mars relevant groundwater have proposed models, but few have looked at the geological evidence of groundwater upwelling in deep closed basins in the northern hemisphere equatorial region. Geological evidence of groundwater upwelling in these deep basins is a key point that will help to validate present-day models and to better constraint them in the future. Observations in the northern hemisphere show evidence of a planet-wide groundwater system on Mars. The elevations of these water-related morphologies in all studied basins lie within the same narrow range of depths below Mars datum and notably coincide with the elevation of some ocean shorelines proposed by previous authors.

During a cruise on the R/V Kilo Moana in 2004, we mapped 12 debris avalanches from volcanoes in the Bismarck volcanic arc, estimated their sizes and computed the size of potential tsunami run-up in major local population centers from these features. We used the towed side-scan instrument Hawaii-MR1, the hull-mounted EM120 system for swath bathymetry and backscatter intensity, a shallow penetration chirp system, several bottom camera tows and selected cores. We calibrate our computations with the known tsunami run-up of the Ritter collapse. Even the small collapses may have had significant run-up on near-by coastlines. Had any of the collapses we have identified occurred in modern times each would affect a presently populated region of the coastline to a moderate or significant degree.

Bangladesh, at the confluence of the sediment-laden Ganges and Brahmaputra Rivers, supports an enormous and rapidly growing population (>140 million in 2011), across low-lying alluvial and delta plains that have accumulated over the past few thousand years. It has been identified as one of the most vulnerable places in the world to the impacts of climate change and sea-level rise. Although abundant sediment supply has resulted in accretion on some parts of the coast of Bangladesh, others are experiencing rapid erosion. We report a systematic assessment of rates of shoreline change over a 20-year period from 1989 to 2009, using Landsat satellite images with pixel resolution of 30 m on the ground. A Band ratio approach, using Band-5 divided by Band-2, discriminated the water line on images that were largely cloud-free, adequately registered, and at comparable tidal stages. Rates of shoreline change were calculated for >16,000 transects generated at 50 m intervals along the entire mainland coastline (>1,100 km) and major islands, using the End Point Rate (EPR) method in the Digital Shoreline Analysis System (DSAS) extension in ArcGIS®. Erosion characterises most of the seaward margin of the Sundarbans in western Bangladesh. Retreat rates of up to 20 m/yr are typical, with little evidence that local devastation of the mangrove fringe by Cyclone Sidr in November 2007 had resulted in uncharacteristic long-term rates of retreat where it made landfall. Erosion exceeded accretion in the Barguna Patuakhali coastal zone, most of which eroded at up to 20 m/yr, but with truncation of the southern tip of the Patharghata Upazila at up to 100 m/yr. In Bhola, erosion at rates of up to 120 m/yr were observed along much of the coast, but in the Noakhali Feni coastal zone, similar rates of erosion were balanced by rapid accretion of the main promontory by more than 600 m/yr. Rates of change were more subdued in the Chittagong and Cox’s Bazar coastal zones of southeast Bangladesh. Islands in the Meghna estuary were especially dynamic; Hatiya Island accreted along some of its shoreline by 50 km2 between 1989 and 2009, but lost 65 km2 through erosion elsewhere, resulting in the island moving south. Similar trends were observed on adjacent islands. The overall area changed relatively little across the entire coastline over the 20-year period with accretion of up to 315 km2, countered by erosion of about 307 km2.Bangladesh, at the confluence of the sediment-laden Ganges and Brahmaputra Rivers, supports an enormous and rapidly growing population (>140 million in 2011), across low-lying alluvial and delta plains that have accumulated over the past few thousand years. It has been identified as one of the most vulnerable places in the world to the impacts of climate change and sea-level rise. Although abundant sediment supply has resulted in accretion on some parts of the coast of Bangladesh, others are experiencing rapid erosion. We report a systematic assessment of rates of shoreline change over a 20-year period from 1989 to 2009, using Landsat satellite images with pixel resolution of 30 m on the ground. A Band ratio approach, using Band-5 divided by Band-2, discriminated the water line on images that were largely cloud-free, adequately registered, and at comparable tidal stages. Rates of shoreline change were calculated for >16,000 transects generated at 50 m intervals along the entire mainland coastline (>1,100 km) and major islands, using the End Point Rate (EPR) method in the Digital Shoreline Analysis System (DSAS) extension in ArcGIS®. Erosion characterises most of the seaward margin of the Sundarbans in western Bangladesh. Retreat rates of up to 20 m/yr are typical, with little evidence that local devastation of the mangrove fringe by Cyclone Sidr in November 2007 had resulted in uncharacteristic long-term rates of retreat where it made landfall. Erosion exceeded accretion in the Barguna Patuakhali coastal zone, most of which eroded at up to 20 m/yr, but with truncation of the southern tip of the Patharghata Upazila at up to 100 m/yr. In Bhola, erosion at rates of up to 120 m/yr were observed along much of the coast, but in the Noakhali Feni coastal zone, similar rates of erosion were balanced by rapid accretion of the main promontory by more than 600 m/yr. Rates of change were more subdued in the Chittagong and Cox’s Bazar coastal zones of southeast Bangladesh. Islands in the Meghna estuary were especially dynamic; Hatiya Island accreted along some of its shoreline by 50 km2 between 1989 and 2009, but lost 65 km2 through erosion elsewhere, resulting in the island moving south. Similar trends were observed on adjacent islands. The overall area changed relatively little across the entire coastline over the 20-year period with accretion of up to 315 km2, countered by erosion of about 307 km2.

We calculated the expected impact on the Italian coast of the Adriatic Sea of a large set of tsunamis resulting from potential earthquakes generated by major fault zones. Our approach merges updated knowledge on the regional tectonics and scenario-like calculations of expected tsunami impact. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

The Zambezi River is the fourth largest river in Africa (after the Congo, Nile, and Niger), and it is the largest African river flowing into the Indian Ocean. The lower Zambezi in Mozambique is influenced by the presence of two very large reservoirs (Kariba dam and Cahora Bassa dam) that have modified the natural seasonal flows, as well as the sediment balance and morphology of the river. In particular, downstream of the Cahora Bassa reservoir down to the delta, no negligible effects are reported to take place, such as local scour, bank collapse, and shoreline progressive erosion . In order to quantify and possibly mitigate these effects, a simplified numerical model of the sediment transport and erosion/sedimentation phenomena along the lower Zambezi has been developed, capable to deal with the scanty and uncertain data available. Indeed, besides the systematic flow records at the dam sites and few occasional measurements of turbidity and bottom granulometry, only the Digital Elevation Model (DEM) of the river will be used for the model. The objective of this paper is to predict the present and future effects of the presence of the Kariba and Cahora Bassa dams on the downstream morphology, integrating the few coarse and nonsimultaneous data, somehow improving their overall quality. The model reproduces the time and space propagation of the disturbances, that confirm, with more generality, the qualitative response of the river to the constructions of dams, anticipated by various geomorphologists. In fact, the reduction of waterflow seems to have an immediate effect downstream by initially fostering the sediment deposition. Subsequently, the total interception of sediment by the dam slowly takes over and inverts this tendency. A slightly smaller aggradation (or slightly larger degradation) rate with respect to the natural conditions (no dams) seems to represent the dominant effect of damming in the long term evolution of the lower Zambezi.

a surtseyan eruption occurred around Hunga Ha'apai Island, Tonga. A series of observations from the high-spatial resolution Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), and the high-temporal resolution Moderate Resolution Imaging Spectroradiometer (MODIS), was used to estimate the magnitude, location, start time, and duration of the eruption, and measure the evolving characteristics of the new Hunga Ha'apai Island. The eruption start time was estimated to be between 01:50 and 11:10 local time, on March 17, 2009 (i.e., between 12:50 and 22:10 UTC, March 16). The initial explosive phase lasted 3-5 days and consisted of multiple steam and tephra explosions from two distinct vent sources, one on the northwest side, and another about 100 m off the south shore of the pre-existing island. The eruption plume reached 4.0 to 7.6 km altitude above sea level, and tephra added new land around each of the vents, initially tripling the area of the pre-existing island. The next phase of steaming from newly formed crater lakes around the vents lasted a few days. Three warm crater lakes formed initially, but disappeared with time as the shoreline eroded. After~2 months, vegetation that was initially buried by tephra was recovering; after~10 months, the size of the island had eroded down to~twice that of the pre-existing island, and the one remaining crater lake had a temperature of~68 ±17°C. The volume of erupted material was estimated to be~0.0176 km 3 and the volcanic explosivity index (VEI) was estimated to be VEI= 2.