The Retreat of the North American Ice Sheet and Shifts in Cyclone Tracks

The alternating retreats and readvances of the North American ice sheet from 18,000 years to 6000 years ago are attributed to shifts in storm tracks. According to the author's theory, proglacial lakes formed during the retreat of the ice sheet became the paths of cyclone tracks whose precipitation led to an accumulation of ice and a readvance of the ice sheet. The readvance into the proglacial lake basins resulted in a reduction or southward shift of cyclone tracks, and this in turn led to a halt of the readvance and a retreat of the ice sheet. As soon as the ice had vacated the Great Lakes basin, the cyclone tracks would once again shift northward and the process of readvance would start all over again.     

Reactive transport and thermo‐hydro‐mechanical coupling in deep sedimentary basins affected by glaciation cycles: model development,verification, and illustrative example

Deep sedimentary basins are complex systems that over long time scales may be affected by numerous interacting processes including groundwater flow, heat and mass transport, water–rock interactions, and mechanical loads induced by ice sheets. Understanding the interactions among these processes is important for the evaluation of the hydrodynamic and geochemical stability of geological CO₂ disposal sites and is equally relevant to the safety evaluation of deep geologic repositories for nuclear waste. We present a reactive transport formulation coupled to thermo‐hydrodynamic and simplified mechanical processes. The formulation determines solution density and ion activities for ionic strengths ranging from freshwater to dense brines based on solution composition and simultaneously accounts for the hydro‐mechanical effects caused by long‐term surface loading during a glaciation cycle. The formulation was implemented into the existing MIN3P reactive transport code (MIN3P‐THCm) and was used to illustrate the processes occurring in a two‐dimensional cross section of a sedimentary basin subjected to a simplified glaciation scenario consisting of a single cycle of ice‐sheet advance and retreat over a time period of 32 500 years. Although the sedimentary basin simulation is illustrative in nature, it captures the key geological features of deep Paleozoic sedimentary basins in North America, including interbedded sandstones, shales, evaporites, and carbonates in the presence of dense brines. Simulated fluid pressures are shown to increase in low hydraulic conductivity units during ice‐sheet advance due to hydro‐mechanical coupling. During the period of deglaciation, Darcy velocities increase in the shallow aquifers and to a lesser extent in deeper high‐hydraulic conductivity units (e.g., sandstones) as a result of the infiltration of glacial meltwater below the warm‐based ice sheet. Dedolomitization is predicted to be the most widespread geochemical process, focused near the freshwater/brine interface. For the illustrative sedimentary basin, the results suggest a high degree of hydrodynamic and geochemical stability.     

鄂尔多斯高原自然背景和明清时期的土地利用

鄂尔多斯高原位于我国北方沙漠-黄土边界带的关键位置上,通过百年来沙漠-黄土边界带概念的形成考察,从学术史上获得该论题蕴含有过渡带、敏感带、生态交错带内涵,这是众多学科研究意义所在。明代为防御元蒙势力,沿长城地带实行军屯,清代限于人口压力和财政因素,从长城内到长城外,将"变刍牧而桑麻"的活动扩展到大半个高原。汲取学术界已有成果,尤其是以长城作为判断毛乌素沙地南移及其与明清垦殖活动关系的一种考察方式,在影响毛乌素沙地的走向和幅度上,认为自然因素更显重要。尽管人类利用土地的形式和规模在逐渐升级,但在明清时期的演变过程中,仍只是作为荒漠-草原彼此进退的一种参与力量。     

A simple theoretical model of the diffraction of VLF electromagnetic waves by the Antarctic icecap

The Antarctic continent has been modelled as a spherical cap whose pole is coincident with that of the South Pole, which totally absorbs VLF radio waves attempting to propagate over it. The propagation of Omega navigation signals around this model icecap has then been computed using Kirchhoff diffraction theory. Spherical caps extending to 66.5 and 75.5°S have been found to accurately model the signals from Omega La Reunion and Argentina, respectively, received on flights between Christchurch, New Zealand and Scott Base in Antarctica, up to the boundary of the theoretical icecap. These model icecaps were found to be good fits to the boundary of the Antarctic continent, when measured at the 1–1.5 km contour of ice thickness, in the region where the VLF waves diffracted around the icecap. The good agreement obtained between the experimental field strength data and those computed theoretically, using only simple diffraction theory, suggests that coastal refraction plays at most only a secondary role in circumpolar propagation.     

Broad-band auroral VLF hiss and inverted-V electron precipitation in the polar magnetosphere

A polar map of the occurrence rate of broad-band auroral VLF hiss in the topside ionosphere was made by a criterion of simultaneous intensity increases more than 5 dB above the quiet level at 5, 8, 16 and 20 kHz bands, using narrow-band intensity data processed from VLF electric field (50 Hz–30 kHz) tapes of 347 ISIS passes received at Syowa Station, Antarctica, between June 1976 and January 1983.The low-latitude contour of occurrence rate of 0.3 is approximately symmetric with respect to the 10–22 MLT (geomagnetic local time) meridian. It lies at 74° around 10 MLT, and extends down to 67° around 22 MLT. The high-latitude contour of 0.3 lies at invariant latitude of about 82° for all geomagnetic local times. The polar occurrence map of broad-band auroral VLF hiss is qualitatively similar to that of inverted-V electron precipitation observed by Atmospheric Explorer.(AE-D) (Huffman and Lin, 1981, American Geophys. Union, Geophysics Monograph, No. 25, p. 80), especially concerning the low-latitude boundary and axial symmetry of the 10–22 h MLT meridian.The frequency range of the broad-band auroral VLF hiss is discussed in terms of whistler Aode Cerenkov radiation by inverted-V electrons (1–30 keV) precipitated from the boundary plasma sheet. High-frequency components, above 12 kHz of whistler mode Cerenkov radiation from inverted-V electrons with energy below 40 keV, may be generated at altitudes below 3200 km along geomagnetic field lines at invariant latitudes between 70 and 77°. Low-frequency components below 2 kHz may be generated over a wide region at altitudes below 6400 km along the same field lines. Thus, the frequency range of the downgoing broad-band auroral hiss seems to be explained by the whistler mode Cerenkov radiation generated from inverted-V electrons at geocentric distances below about 2 R_E (Earth's radius) along polar geomagnetic field lines of invariant latitude from 70 to 77°, since the whistler mode condition for all frequencies above 1 kHz of the downgoing hiss is not satisfied at geocentric distance of 3 r_e on the same field lines.     

Scottish landform examples 45: Sgriob na Caillich: a landslide-sourced medial moraine on the Isle of Jura

ABSTRACT

Medial moraines deposited by former glaciers and ice sheets are rare in Scotland. The most prominent example is the Sgriob na Caillich moraine, which consists of two to four parallel belts of angular quartzite boulders that extend northwestwards for over 3.5?km from the SW flank of Beinn an Oir on the Isle of Jura. The boulder belts extend to within 300?m of the present coastline, where they are truncated by a low bluff and raised marine terrace. The source of the moraine coincides with bedrock gullies and cliffs that represent the scars of former rock-slope failure(s), indicating that the moraine debris was sourced by one or more rockfalls or rockslides onto the ice surface after Beinn an Oir had emerged from the thinning ice cover as a nunatak. Exposure dating of boulders on the moraine indicate that it formed at 16.6?±?0.8?ka, consistent with the timing of ice-sheet retreat in this sector. The alignment of the moraine indicates ice-margin retreat to the SE; as regional ice-sheet retreat across the adjacent offshore shelf was to the NE, this anomaly implies that a residual icefield became stranded on Jura during ice-sheet retreat.     

Deglaciation and Human Colonization of Northern Europe

Few places worldwide experienced Late Glacial ecological shifts as drastic as those seen in the areas covered by, or adjacent to, the massive ice sheets that blanketed much of the northern hemisphere. Among the most heavily glaciated regions, northern Europe underwent substantial ecological shifts during and after the Last Glacial Maximum. The climatically unstable Pleistocene–Holocene transition repeatedly transformed far-northern Europe, placing it among the last regions to be colonized by Paleolithic societies. As such, it shares paleoenvironmental and archaeological analogues with other once glaciated areas where human populations, entrenched in periglacial environments prior to glacier retreat, spread into newly deglaciated territories. Perhaps most significant for northern Europeans were post-glacial effects of the Younger Dryas and Preboreal periods, as shifts in climate, plant, and animal communities elicited several adaptive responses including innovation, exploration, and the eventual settlement of once glaciated landscapes. This paper is a detailed review of existing archaeological and paleoecological evidence pertaining to the Late Upper Paleolithic of northern Europe, and offers theoretical observations on human colonization models and ecological responses to large-scale stadial and interstadial events.     

GLACIATION OF BONAVISTA PENINSULA, NORTHEAST NEWFOUNDLAND

Over Bonavista Peninsula, in northeast Newfoundland, ice-flow directional indicators reveal two styles of glaciation. The inner part was glaciated by ice of the Newfoundland Ice Cap, flowing northeast but drawn down strongly into deep channels in Bonavista and Trinity bays and basally deflected northward by a line of hills bisecting the peninsula. The outer peninsula was almost completely glaciated by the contiguous, dynamically independent Bonavista Ice Divide, with coastward flow. Near the northeast extremity a low plateau, mantled with blockfield and bearing no obvious traces of glaciation, is flanked by a subdued end moraine. The moraine is argued to represent the local entire Wisconsinan glaciation limit. Evidence from soil development on the moraine and elevations of emerged post-glacial shore features, as well as from comparison with glacial history in nearby areas, is used to argue a late Wisconsinan (pre-12,000–13,000 BP) age for the later part of glaciation. Evidence of widespread till deposition far offshore can be harmonized with evidence of incomplete Wisconsinan glaciation onshore by postulating persistent discharge of inland ice through the deep, compound fiord basins that flank Bonavista and other east Newfoundland peninsulas Les indicateurs du passage des glaciers dans la péninsule de Bonavista située au nord-est de Terre-Neuve signalent l'oeuvre de deux styles de glaciation. La Calotte Glaciaire de Terre-Neuve recouvrait tout I'intérieur de la Péninsule; se déplaçantvers le nord-est, elle était forcee de suivre par les baies profondes de Bonavista et de Trinité, et détournée à sa base en direction du nord par les collines qui franchissent la péninsule du nordau sud. Pour sa part, I'extérieur de la péninsule gisait entièrement sous le Diviseur Glaciaire Bonavista, qui tout en étant contigu obéissait à une dynamique indépendante et s'écoulait en direction des côtes. A I'extrémité nord-est de la pénin sule, sous un manteau de blocs rocheux, se trouve un bas plateau qui ne porte aucune trace de glaciation et qui est bordé d'une fine moraine terminale. Selon l'argument proposé, cette moraine représente en cet endroit la limite extrême des glaciers du Wisconsin. Des indices provenant de la formation des sols sur cette moraine et des hauteurs atteintes par la mer postglaciaire, de même qu'une comparaison avec l'histoire des glaciations dans les zones environnantes, permettent d'avancer que la fin de la dernière glaciation remonte à celle du Wisconsin (avant 12 000 à 13 000 ans AP). Des liens existent entre les dépots très répandus de till, loin au large des côtes, et les indices d'une glaciation incomplète durant le Wisconsin sur ces côtes, dans la mesure où l'on postule qu'il y eut une décharge soutenue de glace en provenance de l'intérieur, le long des fiords profonds et complexes qui bordent la peninsule de Bonavista de même que d'autres péninsules de Terre-Neuve.     

Natural degradation of earthworks,trenches, walls and moats,Northern Thailand

We here investigate the geometry, age, and history of several enigmatic northern Thailand earthwork entrenchments that are mostly located on hills and could not have held water to form moats. The earthworks are either oval or rectangular in plan view and typically encircle 0.3 to 1?sq km areas with no potsherd debris that would indicate former towns. Most trenches are 3–5?m deep with inner walls 4.5–8?m high. Some encircling earthworks are concentric double trenches spaced approximately 10?m apart. Historians have suggested these earthworks enclosed defensible areas where people in outlying villages sought refuge when under attack by neighboring rulers, the Chinese Ho, or the Burmese. We argue that some encircling entrenchments may have been for the capture or containment of elephants. Nearly all of the once near-vertical original walls have degraded to slopes of 32–47°. Fitting calculated curves of the diffusion-based scarp-degradation model to our height-slope data, and assuming most scarps have degraded since the end of La Na Kingdom time a.d. 1558, we derive a diffusion coefficient of 0.002?m² y^?1. Slopes of the rectangular earthwork at Souvannkhomkham, Laos, across the Mekong River from Chiang Saen Noi, are significantly more degraded (approximately 32°), indicating an age of 800–1200 years. Locations of these earthworks are established in hope that they will be preserved as part of the Thai and Lao archaeological legacy.     

Monks and Local Communities: The Late-medieval Landscape of Troed y Rhiw,Caron Uwch Clawdd,Ceredigion

Abstract

In a zone of improved upland pasture some 2 km east of the Cistercian monastery of Strata Florida (Ystrad Fflur), Ceredigion, are the earthwork remains of a 'sheepcote' and four abandoned medieval farms, one probably originating as a monastic sheep-handling station. Documentary evidence and field observation suggest that these farms have preserved their late-medieval forms in a relatively unmodified state. Three were apparently situated along a contemporary ffridd boundary (head dyke) that separated a zone of pasture and perhaps arable land from mountain pasture. We cannot establish the relationship between the 'sheepcote' and the 'farms' through field observation alone, nor do we know the absolute age of the ffridd boundary. Our paper describes and briefly discusses the character and local context of the area defined by the latter. The pattern of land-use is comparable to that in Swaledale (North Yorkshire), an area that has been discussed on the one hand in terms of patterns of townships (hamlets) and their land-use zones, and on the other in terms of monastic enterprise and the identification of 'vaccaries'. In the study of 'monastic landscapes', we risk becoming preoccupied with estate economies and the identification of 'tool-kits', at the expense of dealing with the complexity of relationships between monasteries and local communities.     

A late Devensian Nunatak on the Knoydart peninsula,NW Scotland: Implications for ice‐sheet reconstruction

Geomorphological mapping and analysis of soil mineralogy indicates that all summits on the Knoydart Peninsula were over‐ridden by the last ice sheet apart from Ladhar Bheinn (1020 m), where the ice attained a maximum altitude of c. 950 m. This figure is consistent with evidence from adjacent areas and suggests that the last ice sheet descended westwards across Knoydart from c. 1000 m to c. 900 at the west coast, implying that most theoretically‐based ice‐sheet models are substantially in error in this area.     

Long‐term chemical evolution and modification of continental basement brines – a field study from the Schwarzwald,SW Germany

Highly saline, deep‐seated basement brines are of major importance for ore‐forming processes, but their genesis is controversial. Based on studies of fluid inclusions from hydrothermal veins of various ages, we reconstruct the temporal evolution of continental basement fluids from the Variscan Schwarzwald (Germany). During the Carboniferous (vein type i), quartz–tourmaline veins precipitated from low‐salinity (<4.5wt% NaCl + CaCl₂), high‐temperature (≤390°C) H₂O‐NaCl‐(CO₂‐CH₄) fluids with Cl/Br mass ratios = 50–146. In the Permian (vein type ii), cooling of H₂O‐NaCl‐(KCl‐CaCl₂) metamorphic fluids (T ≤ 310°C, 2–4.5wt% NaCl + CaCl₂, Cl/Br mass ratios = 90) leads to the precipitation of quartz‐Sb‐Au veins. Around the Triassic–Jurassic boundary (vein type iii), quartz–haematite veins formed from two distinct fluids: a low‐salinity fluid (similar to (ii)) and a high‐salinity fluid (T = 100–320°C, >20wt% NaCl + CaCl₂, Cl/Br mass ratios = 60–110). Both fluids types were present during vein formation but did not mix with each other (because of hydrogeological reasons). Jurassic–Cretaceous veins (vein type iv) record fluid mixing between an older bittern brine (Cl/Br mass ratios ~80) and a younger halite dissolution brine (Cl/Br mass ratios >1000) of similar salinity, resulting in a mixed H₂O‐NaCl‐CaCl₂ brine (50–140°C, 23–26wt% NaCl + CaCl₂, Cl/Br mass ratios = 80–520). During post‐Cretaceous times (vein type v), the opening of the Upper Rhine Graben and the concomitant juxtaposition of various aquifers, which enabled mixing of high‐ and low‐salinity fluids and resulted in vein formation (multicomponent fluid H₂O‐NaCl‐CaCl₂‐(SO₄‐HCO₃), 70–190°C, 5–25wt% NaCl‐CaCl₂ and Cl/Br mass ratios = 2–140). The first occurrence of highly saline brines is recorded in veins that formed shortly after deposition of halite in the Muschelkalk Ocean above the basement, suggesting an external source of the brine's salinity. Hence, today's brines in the European basement probably developed from inherited evaporitic bittern brines. These were afterwards extensively modified by fluid–rock interaction on their migration paths through the crystalline basement and later by mixing with younger meteoric fluids and halite dissolution brines.     

Effects of a New Hydrological Barrier on the Temperatures in the Organic Archaeological Remains at Bryggen in Bergen,Norway

The World Heritage Site of Bryggen in Bergen, Norway, has experienced significant degradation of archaeological deposits as a consequence of changes in the soil water and groundwater balance after urban redevelopment adjacent to the heritage site. Additionally, groundwater temperatures below the heritage site were found to be significantly higher closer to the redeveloped area. One of the main mitigation measures taken to reduce the degradation of the archaeology has been the construction of a hydrological barrier along the sheet piling that divides the redeveloped area and the historic site. A shallow subsurface infiltration system was designed to achieve groundwater levels and flow conditions that are optimal for the preservation of archaeological remains directly along the sheet pile, while reducing drainage and subsidence also further upstream. Monitoring of groundwater level and temperatures after implementation of the hydrological barrier shows that groundwater levels and flow conditions have improved with respect to optimal preservation conditions, and groundwater temperatures have generally been reduced by up to 2 °C.     

DAMMING JAMES BAY: I. POTENTIAL IMPACTS ON COASTAL CLIMATE AND THE WATER BALANCE

The proposed grand Canal project calls for the damming of James Bay and the diversion of its water southward. This first part of a two-part study models some potential impacts on the climate, water balance, and growth patterns in the James Bay coastal zone. Use is made of a linear relationship of Bowen ratio and temperature, developed from studies of coastal wetlands in southern and northwestern James Bay and central Hudson Bay. It is hypothesized that changing James Bay into a fresh-water lake and disrupting its coastal currents would result in a delayed Bay ice melt of unknown length in the spring. Allowing a delay to vary between 0 and 30 days results in the prediction of lesser evaporation and greater water surplus. These differences in magnitude increase with the length of delayed melt, but in all cases are most strongly evident during the peak of the growing season. Colder and wetter conditions would have a strong ecological impact on all coastal areas of western and southern James Bay. In the northwest this could change the species composition of coastal flora, cause forests to retreat from the coast, and result in the growth of permafrost there.     

PALEOGEOGRAPHY,TOPONYMY AND ETHNOGENESIS

An attempt is made by a Lithuanian physical geographer to combine the findings of paleogeography and place-name studies in shedding light on the time and place of the original settlement of the Indo-European peoples. The author also suggests that plausible elements in folk legend are susceptible to paleogeographic analysis, and he illustrates the point by relating Lithuanian folk legends about the origin of lakes to known thermokarstic processes giving rise to cave-in lakes. On the basis of a paleogeographic analysis of Lithuanian place names resembling the name Dunojus (Danube), the author suggests that the name of the Danube River is derived from an Indo-European root word such as duna, signifying an inlet or estuary of Late Pleistocene waterbodies with a sandy, dunelike shoreline. The vocabulary of Indo-European languages relating to features in the natural environment is used in establishing the time and location of the settlement of Indo-European peoples. On the basis of correspondences for tree names in the various Indo-European languages, the author concludes that the original Indo-European proto-ethnos sought refuge in the Pomeranian substage of the Late Pleistocene (about 20,000 years ago) in the mountain caves of central Europe. With the retreat of the ice sheet, the original Indo-Europeans began to migrate northward, and it was in the new areas of settlement in the plains of northern Europe that the Germanic, Slavic and Baltic branches of the Indo-Europeans were formed.     

万里长城的地理界线意义

长城,不仅是中华民族古老文化的象征,而且是一条实际存在的重要地理界线。历代长城的布设都是以自然地理环境为基础,其走向与我国半湿润与干旱气候分界线基本一致。因此,长城也就成为我国农区和牧区分界线的标志。长城的延伸或回退,基本上反映了农区与牧区的扩张或收缩。从政治地理的角度来考察长城。可以认为,它是我国历史上各民族政治力量相互对峙、较量形成的"力"的平衡带,长城,一方面发挥了分隔两个政治单元的功能,它们延伸或收缩在一定程度上反映了两种力量对比的变化;另一方面,在先进与落后两种势力的对撞中.客观上却促进了相互间经济和文化的交流,促进了不同民族的融合。今日长城作为领土扩张和防御的军事设施作用已不复存在。但是长城在地理上的许多界限指标意义仍然存在,它依然是许多地理事物的敏感地区。     

The last glaciers in part of the South East Grampians

In an area of 400 sq km in the south east Grampians including Glen Esk, Glen Clova and part of Glen Muick the limits of former corrie glaciers, valley glaciers and a plateau ice‐cap with associated outlet glaciers have been mapped. The limits of the former corrie and valley glaciers are often clearly defined by end moraines, boulder‐strewn ground, the down‐valley termination of hummocky moraines and/or the limits of meltwater channel systems, while in suitable locations outwash terraces usually occur. The glaciers are considered to have formed during the Loch Lomond (pollen zone III) Readvance, when new glaciers developed in upland sources following complete ice‐sheet decay. The readvance was accompanied in granite areas by the formation of large solifluction lobes, these lobes being found only outside the mapped ice limits. The interpretations presented are not in accord with those recently given by D. E. Sugden for the western Cairngorms.     

Human impact around settlement sites: a phytolith and mineralogical study for assessing site boundaries,phytolith preservation,and implications for spatial reconstructions using plant remains

Defining the extent of human activity around settlement sites is of particular significance in archaeology as it may define peripheral activity areas and thus the site's boundary. In Near Eastern archaeology, site boundaries are usually defined by the presence of architectural and other macroscopic archaeological remains. Here we use the phytolith concentrations and morphotype assemblages, as well as changes in the mineralogical composition of the sediments in and around the small Iron Age site of Izbet Sartah in central Israel to determine the site boundaries. The site has a shallow stratigraphy and highly bioturbated sediments. Coincidental changes in the clay/quartz ratio and phytolith concentrations define the boundary between high and low impact anthropogenic activities. This boundary is generally some 20 m away from the architectural remains. In addition, we note that the phytoliths in the site's core show clear evidence of having been affected by chemical dissolution (i.e., diagenesis), while those in the vicinity of the site's boundary have undergone severe diagenesis. These observations indicate that phytolith diagenesis will affect site boundaries determination, as well as phytolith-based reconstructions of activity areas. We propose that phytolith preservation depends on the initial amount of available silica, the depth of burial with respect to the active root area of modern vegetation, and the presence of fresh phytoliths in the soil.     

Landscapes at the Periphery of Glacierization – Retrospect and Prospect

This paper reviews the evolution of palaeoglaciological reconstructions in regions at the periphery of glacierization, where an improved understanding of the role of glacial thermal regime has helped refine the delimitation of ice sheet maxima. Also significant has been the recognition in numerical models that some areas, especially ice sheet marginal zones, are subject to short periods of ice occupancy and hence that glacial landsystem signatures can be extremely subtle. This is compounded wherever cold-based conditions dominate during early stages of ice sheet recession, giving rise to a landform imprint typical of peripheral regions and hence often misinterpreted as unglaciated or glaciated only by older glaciations. Subtle landform imprints include meltwater channels, thin glacigenic veneers or scattered erratics and modified tors. More substantial glacigenic landform-sediment assemblages (‘drift belts’) do not always represent ice sheet maxima but instead may record significant changes in thermal regime, possibly linked to periods of ice-marginal stabilization. Some upland areas that lie beyond the traditionally demarcated limits of glaciation (e.g. Dartmoor in SW England) may contain subtle evidence of satellite ice cap development which has been overlooked due to the strong periglacial landform signature.     

MICROZONATION OF THE EXPECTED SEISMIC SITE EFFECTS ACROSS PORT VILA,VANUATU

The city of Port Vila, Vanuatu, is located in one of the most active seismic regions on earth. Earthquakes are felt frequently and, due to very rapid plate convergence rates, return period of large earthquakes (M>6) in the New Hebrides Benioff zone can be less than 10 years. Even though Port Vila does not lie on an identified seismic fault zone, strong motions by nearby earthquakes have to be expected due to the city's geographical location close to the plate boundary of New Hebrides convergence zone. An accurate estimation of the seismic ground motion across the city is of prime importance for urban developments and mitigation of earthquake risk. Following many examples of monitored strong earthquakes in the current century, it is evident that the local site effects may have a dominant contribution to the intensity of damage and destruction. In this study we focussed on the first stage of associating site effects and seismic hazard by preparing a microzonation map for Port Vila. The seismic microzonation of the city has been carried out to provide a detailed map of the zones that exhibit site effects in terms of resonance frequencies and approximated amplification of the ground shaking. Having in mind that these data will be used in improving building design to sustain strong ground motions, our analysis is limited to the frequency band of 1–10 Hz, corresponding to the expected resonance of different types of buildings in Port Vila. The Nakamura technique has been used to estimate site amplification effects from single station noise recordings. Interestingly, excluding one site located on an old dump zone, the amplification factors at about the 100 sites surveyed in Port Vila remain below 3 with an average well below 2 in the 1 to 10 Hz frequency band. These results suggest that there is no significant Vs velocity change in consequently layered material and that the uppermost sedimentary layers in the surveyed down town area are relatively thin. These observations are in agreement with the mapping of limestone terraces throughout Port Vila area. However, both the surface geology and results from seismic zonation indicate a thicker (up to several tens of meters) sedimentary cover around the Bauerfield airport and in the Mele terrace zone. Low resonance frequencies (around and below 1 Hz) and amplification factor of the order of 5 were observed over this large area, immediately outside Port Vila. Any building development in this area should take these results into account.