A lesson from cyclone Larry: An untold story of the success of good coastal planning

When tropical cyclone Larry crossed the Queensland coast on 20 March 2006, commercial, recreational and naval vessels in the port of Cairns, 60 km north of the eye of the cyclone and others closer to the eye, were protected from the destructive winds by sheltering in deep mangrove creeks in Trinity Inlet and off other coastal rivers. The Trinity Inlet mangroves are protected under the comprehensive multi-use Trinity Inlet Management Plan, agreed by the local and state government agencies (Cairns City Council, the Cairns Port Authority and the Queensland Government). Using this Australian example and one from the town of Palompon in Leyte province, central Philippines, we show how long-term mangrove habitat protection resulting from well-conceived coastal planning can deliver important economic and infrastructure benefits.     

Assessing the potential for CO2 adsorption in a subbituminous coal,Huntly Coalfield,New Zealand,using small angle scattering techniques

Small angle scattering techniques (SAXS and SANS) have been used to investigate the microstructural properties of the subbituminous coals (R_max 0.42–0.45%) from the Huntly Coalfield, New Zealand. Samples were collected from the two thick (> 5 m) coal seams in the coalfield and have been analysed for methane and carbon dioxide sorption capacity, petrography, pore size distribution, specific surface area and porosity.Specific surface area (SSA) available for carbon dioxide adsorption, extrapolated to a probe size of 4 Å, ranged from 1.25 × 10⁶ cm^? 1 to 4.26 × 10⁶ cm^? 1 with total porosity varying from 16% to 25%. Porosity was found to be predominantly composed of microporosity, which contributed the majority of the available SSA. Although considerable variation was seen between samples, the results fit well with published rank trends.Gas holding capacity at the reservoir pressure (approximately 4 MPa) ranged from 2.63 to 4.18 m³/t for methane on a dry, ash-free basis (daf) and from 22.00 to 23.72 m³/t daf for carbon dioxide. The resulting ratio of CO₂:CH₄ ranged from 5.7 to 8.6, with an average of 6.7:1.Holding capacities for both methane and carbon dioxide on a dry ash free basis (daf) were found to be correlated with sample microporosity. However, holding capacities for the two gases on an as analysed (aa) basis (that is including mineral matter and moisture), showed no such correlation. Carbon dioxide (aa) does show a negative correlation with both specific surface area and microporosity. As the coals have low inorganic matter content, the reversal is thought to be related to moisture which is likely concentrated in the pore size range 12.5–125 Å. Methane holding capacity, both daf and aa, correlates with macroporosity, thus suggesting that the holding capacity of micropores is diminished by the presence of moisture in the pores.     

Uncertainty of gas saturation estimates in a subbituminous coal seam

To assess the commercial viability of a coalbed methane prospect two of the key geological parameters measured are gas content (desorbed gas) and gas holding capacity (adsorption capacity). These two measures, together with reservoir pressure, give an estimate of the gas saturation of the reservoir. Typically gas saturation has been assessed by collecting one adsorption isotherm sample and assuming it is representative of the whole seam reservoir conditions. This study addresses that assumption.To understand the level of variation, and thus the inherent uncertainty in saturation, one core (Jasper-1) from the Huntly coalfield in New Zealand was analysed in detail. Ten samples (representing the whole coal seam) were placed into gas desorption canisters and desorbed for ten days and then analysed for adsorption capacity. Desorption analyses for total measured gas content (average in-situ basis) ranged from 2.32 to 2.89 m³/t (standard deviation (sd) = 0.18) and gas adsorptive capacity at 4 MPa (average in-situ basis) from 2.11 to 3.51 m³/t (sd = 0.38) resulting in saturations ranging from 66% to 120% (sd = 15).Determination of how many samples are required to make a realistic assessment of average reservoir properties requires a consideration of: (i) the level of accuracy desired, (ii) the limit of accuracy possible, which is governed by the magnitude of experimental error, and (iii) the innate variability of the seam. It was found that a minimum of five samples each for adsorption and desorption were required in order to significantly decrease the uncertainty in gas saturation estimates for a subbituminous coal.     

Sampling of Mars analogue materials in a laboratory environment

Acta Geotechnica - Two laboratory test series were performed with the aim of ensuring the proper functionality of the key sampling mechanisms installed aboard the Mars rover ExoMars, currently...     

Seagrass-Watch: Engaging Torres Strait Islanders in marine habitat monitoring

Involvement in scientifically structured habitat monitoring is a relatively new concept to the peoples of Torres Strait. The approach we used was to focus on awareness, and to build the capacity of groups to participate using Seagrass-Watch as the vehicle to provide education and training in monitoring marine ecosystems. The project successfully delivered quality scientifically rigorous baseline information on the seasonality of seagrasses in the Torres Strait—a first for this region.     

Geology of a submarine volcanic caldera in the Tonga Arc: Dive results

A submersible dive conducted on Volcano #1 located near 21° 09′S–175° 45′W on the Tonga Arc showed that the volcanic edifice with a caldera floor area of 30 km² located at and 450 m deep (b.s.l.=below sea level) was constructed recently during episodic volcanism. The sequential volcanic events are recorded along a faulted terrain formed in response to the collapse of the caldera wall. The post-caldera events are marked by occasional eruptions that have built scoriaceous cones associated with low-temperature hydrothermal venting and localized small-scale collapse features. The stratigraphy of the caldera wall indicates that the volcano was built by explosive volcanism alternating with quieter eruptive events. The repeated, violent explosive events formed ≤ 20 m thick sequences composed of alternating fine-grained ash beds and sand- to boulder-sized pyroclastic layers. During quieter volcanic events, dykes and massive flows intruded and/or accompanied the eruption of the volcaniclastic deposits throughout the sections of the wall explored. Massive columnar-jointed flows consist of viscous, silica-rich lavas forming tabular and giant radial-jointed (GRJ) flows formed in large (> 8 m in diameter) conduits and extruded onto the sea floor. In addition, massive lava flows forming sill-like complexes were observed underneath and near the giant radial-jointed columnar flows. Also, an intermittent quiet type of eruption produced vesicular lava flows, which are interbedded within the pyroclastic layered deposits. The massive and vesicular lavas consist of andesites and dacites with Ca-depleted (pigeonite) and Ca-enriched (salite) pyroxene, and intermediate (andesine-labradorite) to calcic (bytownite) plagioclase. They are depleted in total alkalis (Na₂O + K₂O < 3%), K₂O (< 1%), Zr/Y (< 1.8), Nb/Zr (< 0.01) and light Rare Earth Elements. We interpret that these andesite–dacite series were erupted after undergoing crystal-liquid fractionation in a magma chamber located underneath the caldera floor.     

Estimating Land Surface Evaporation: A Review of Methods Using Remotely Sensed Surface Temperature Data

This paper reviews methods for estimating evaporation from landscapes, regions and larger geographic extents, with remotely sensed surface temperatures, and highlights uncertainties and limitations associated with those estimation methods. Particular attention is given to the validation of such approaches against ground based flux measurements. An assessment of some 30 published validations shows an average root mean squared error value of about 50 W m^?2 and relative errors of 15–30%. The comparison also shows that more complex physical and analytical methods are not necessarily more accurate than empirical and statistical approaches. While some of the methods were developed for specific land covers (e.g. irrigation areas only) we also review methods developed for other disciplines, such as hydrology and meteorology, where continuous estimates in space and in time are needed, thereby focusing on physical and analytical methods as empirical methods are usually limited by in situ training data. This review also provides a discussion of temporal and spatial scaling issues associated with the use of thermal remote sensing for estimating evaporation. Improved temporal scaling procedures are required to extrapolate instantaneous estimates to daily and longer time periods and gap-filling procedures are needed when temporal scaling is affected by intermittent satellite coverage. It is also noted that analysis of multi-resolution data from different satellite/sensor systems (i.e. data fusion) will assist in the development of spatial scaling and aggregation approaches, and that several biological processes need to be better characterized in many current land surface models.     

Cenozoic basin evolution beneath the southern McMurdo Ice Shelf, Antarctica

Fifty-two kilometres of multi-channel seismic reflection data were acquired from the southern McMurdo Ice Shelf (SMIS) during potential drill site investigations for the Antarctic Drilling (ANDRILL) program. The survey was acquired atop 110 to 220 m of floating ice and extended across ablation and accumulation zones of the ice shelf. Seismic processing was tailored to the ice shelf environment, including: datum static corrections to account for changes in the thickness and average velocity of the near-surface firn layer, and changes in the surface elevation across the survey area; residual static corrections to account for near-surface ice shelf irregularities; and two-step predictive deconvolution to suppress ice and firn layer multiples. A model for the ice shelf thickness was also incorporated in the interval velocity model during depth conversion to ensure that the ice shelf structure did not impose non-static shifts on the seismic section.The depth converted CMP stacked sections reveal several N to NE trending normal faults, that offset reflective horizons by up to 150 m within the lower part of the section and form a broad east-dipping, half-graben structure. The seafloor possesses trough and arch morphology in parallel with the half-graben structure. These features are interpreted as the southern extension of the Terror Rift. The rift succession comprises a dislocated (?)early-Miocene synrift package and a relatively undeformed (?)late-Miocene post-rift package separated by an erosional unconformity. The post-rift package infills and onlaps the rift topography, and drapes over the graben system, reaching a maximum thickness of 400 m. Throughout the post-rift phase, the basin was also influenced by Neogene volcanism, evidenced by three small volcanic features within the seismic profiles, and associated successions of inferred volcanic material. An angular unconformity within the post-rift succession is interpreted as a flexural horizon related to the load of Mount Discovery and/or Mount Morning. Up to 150 m of flexural moat fill occurs above this surface at ~ 20 km from the load centres. The post-rift succession also includes several glacio-geomorphic features, the orientation and morphology of which indicate an approximately SW to NE ice flow direction during a mid-Miocene grounding event and a SE to NW ice flow direction during Quaternary ice sheet grounding events.The thickness and lower extent of the rift succession was not able to be determined because signal-to-noise ratio and vertical resolution were low at these depths. Strata from an earlier, Paleogene, rift episode may underlie the Terror Rift succession, or it may be directly underlain by acoustic basement. A Paleogene rift episode has previously been proposed based on the occurrence of Eocene fossiliferous erratics around the margin of the SMIS and the structural setting revealed by the SMIS seismic reflection profiles is consistent with this hypothesis.