School of Earth Sciences - Research Publications

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    Resettlement and the environment in Vietnam: Implications for climate change adaptation planning
    Miller, F ; Dun, O (WILEY, 2019-08)
    Increasingly the environment, and climate risks in particular, are influencing migration and planned resettlement in Vietnam, raising the spectre of increased displacement in a country already confronting serious challenges around sustainable land and water use as well as urbanisation. Planned resettlement has emerged as part of a suite of measures being pursued as part of disaster risk reduction and climate change adaptation strategies. This paper provides an historical, political, legal and environmental overview of resettlement in Vietnam identifying key challenges for framing resettlement as climate change adaptation. The paper outlines the scale of past resettlement in Vietnam, identifying the drivers and implications for vulnerability. Detailed case studies of resettlement are reviewed. Through this review, the paper reflects on the growing threat of climate change and the likelihood of increased displacement associated with worsening climate risks to identify some critical considerations for planned resettlement in climate change adaptation planning.
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    Disoriented geographies: Undoing relations, encountering limits
    Bissell, D ; Gorman-Murray, A (WILEY, 2019-12)
    This paper develops the concept of disorientation as a constitutive but overlooked dimension of mobile life, and it explores the significance of disorientation for geographical thought. Conceptually, the paper argues that disorientation is a productive geographical concept for acknowledging how, at times, bodies can lose their orienting relations to other bodies, to actions, and to situations. These losses are explored through the themes of incomprehension, confusion, and disintegration, respectively. Substantively, through research with mobile worker households in Australia, the paper expands our understanding of geographies of mobility by interrogating non‐traditional but increasingly common living scenarios created by intensified mobility. Methodologically, the paper develops a narrative approach to presenting the richly complex experiences of “left behind” mobile worker partners through impressionistic interview portraits. Disciplinarily, contributing to ongoing debates in geography on relationality and encounter, the paper provides a counterbalance to the dominant focus on relation construction, and it opens up space for thinking differently about what, exactly, is being encountered in disorienting experiences.
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    Observed Relationships Between Sudden Stratospheric Warmings and European Climate Extremes
    King, AD ; Butler, AH ; Jucker, M ; Earl, NO ; Rudeva, I (AMER GEOPHYSICAL UNION, 2019-12-27)
    Abstract Sudden stratospheric warmings (SSWs) have been linked with anomalously cold temperatures at the surface in the middle to high latitudes of the Northern Hemisphere as climatological westerly winds in the stratosphere tend to weaken and turn easterly. However, previous studies have largely relied on reanalyses and model simulations to infer the role of SSWs on surface climate and SSW relationships with extremes have not been fully analyzed. Here, we use observed daily gridded temperature and precipitation data over Europe to comprehensively examine the response of climate extremes to the occurrence of SSWs. We show that for much of Scandinavia, winters with SSWs are on average at least 1 °C cooler, but the coldest day and night of winter is on average at least 2 °C colder than in non‐SSW winters. Anomalously high pressure over Scandinavia reduces precipitation on the northern Atlantic coast but increases overall rainfall and the number of wet days in southern Europe. In the 60 days after SSWs, cold extremes are more intense over Scandinavia with anomalously high pressure and drier conditions prevailing. Over southern Europe there is a tendency toward lower pressure, increased precipitation and more wet days. The surface response in cold temperature extremes over northwest Europe to the 2018 SSW was stronger than observed for any SSW during 1979–2016. Our analysis shows that SSWs have an effect not only on mean climate but also extremes over much of Europe. Only with carefully designed analyses are the relationships between SSWs and climate means and extremes detectable above synoptic‐scale variability.
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    Late Miocene Hinterland Crustal Shortening in the Longmen Shan Thrust Belt, the Eastern Margin of the Tibetan Plateau
    Shen, X ; Tian, Y ; Zhang, G ; Zhang, S ; Carter, A ; Kohn, B ; Vermeesch, P ; Liu, R ; Li, W (AMER GEOPHYSICAL UNION, 2019-11)
    Abstract Long‐term (million year time scale) fault‐slip history is crucial for understanding the processes and mechanisms of mountain building in active orogens. Such information remains elusive in the Longmen Shan, the eastern Tibetan Plateau margin affected by the devastating 2008 Wenchuan earthquake. While this event drew attention to fault deformation on the foreland side (the Yingxiu‐Beichuan fault), little is known about the deformation history of the hinterland Wenchuan‐Maoxian fault. To address this gap, thermochronological data were obtained from two vertical transects from the Xuelongbao massif, located in the hanging wall of the Wenchuan‐Maoxian fault. The data record late Miocene rapid cooling and rock exhumation at a rate of 0.9–1.2 km/m.y. from ~13 Ma to present. The exhumation rate is significantly higher than that in the footwall (~0.3–0.5 km/m.y.), indicating a differential exhumation of ~0.6 km/m.y. across the fault. This differential exhumation provides the first and minimum constraint on the long‐term throw rate (~0.6 km/m.y) of the Wenchuan‐Maoxian fault since the late Miocene. This new result implies continuous crustal shortening along the hinterland fault of Longmen Shan, even though it has not been ruptured by major historic earthquakes. Our study lends support to geodynamic models that highlight crustal shortening as dominating deformation along the eastern Tibetan Plateau.
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    The Impact of a Very Weak and Thin Upper Asthenosphere on Subduction Motions
    Carluccio, R ; Kaus, B ; Capitanio, FA ; Moresi, LN (AMER GEOPHYSICAL UNION, 2019-11-16)
    Abstract Recent geophysical observations report the presence of a very weak and thin upper asthenosphere underneath subducting oceanic plates at convergent margins. Along these margins, trench migrations are significantly slower than plate convergence rates. We use numerical models to assess the role of a weak upper asthenospheric layer on plate and trench motions. We show that the presence of this layer alone can enhance an advancing trend for the motion of the plate and hamper trench retreat. This mechanism provides a novel and alternative explanation for the slow rates of trench migration and fast‐moving plates observed globally at natural subduction zones.
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    Surface Rupture and Distributed Deformation Revealed by Optical Satellite Imagery: The Intraplate 2016 Mw 6.0 Petermann Ranges Earthquake, Australia
    Gold, RD ; Clark, D ; Barnhart, WD ; King, T ; Quigley, M ; Briggs, RW (AMER GEOPHYSICAL UNION, 2019-09-01)
    Abstract High‐resolution optical satellite imagery is used to quantify vertical surface deformation associated with the intraplate 20 May 2016 Mw 6.0 Petermann Ranges earthquake, Northern Territory, Australia. The 21 ± 1‐km‐long NW trending rupture resulted from reverse motion on a northeast dipping fault. Vertical surface offsets of up to 0.7 ± 0.1m distributed across a 0.5‐to‐1‐km‐wide deformation zone are measured using the Iterative Closest Point algorithm to compare preearthquake and postearthquake digital elevation models derived from WorldView imagery. The results are validated by comparison with field‐based observations and interferometric synthetic aperture radar. The pattern of surface uplift is consistent with distributed shear above the propagating tip of a reverse fault, leading to both an emergent fault and folding proximal to the rupture. This study demonstrates the potential for quantifying modest (<1 m) vertical deformation on a reverse fault using optical satellite imagery.
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    The influence of fine-scale topography on the impacts of Holocene fire in a Tasmanian montane landscape
    Cadd, H ; Fletcher, M-S ; Mariani, M ; Heijnis, H ; Gadd, PS (WILEY, 2019-10)
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    Reply to the comments by Pillai, S. P., George, B. G., Ray, J. S., and Kale, V. S., (GJ-19-0112) on Paper: "Depositional history and provenance of cratonic "Purana" basins in southern India: A multipronged geochronology approach to the Proterozoic Kaladgi and Bhima basins" by Joy et al., 2018
    Joy, S ; Patranabis-Deb, S ; Saha, D ; Jelsma, H ; Maas, R ; Soderlund, U ; Tappe, S ; Van der Linde, G ; Banerjee, A ; Krishnan, U ; Somerville, I (WILEY, 2019-09)
    We thank Patil Pillai et al. for preparing a critique on our article (Joy et al., 2018). Patil Pillai et al. contest the analytical procedure utilized for the carbonates and “geological information” documented in our research article and raise concerns on our conclusions. We hereby provide our reply to each of their comments.
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    Reduced rainfall drives biomass limitation of long-term fire activity in Australia's subtropical sclerophyll forests
    Mariani, M ; Tibby, J ; Barr, C ; Moss, P ; Marshall, JC ; McGregor, GB (WILEY, 2019-09)
    AIM: To understand the long‐term drivers of biomass burning in the sclerophyll‐dominated forests of Australia. LOCATION: Swallow Lagoon, North Stradbroke Island, Queensland, Australia. TIME PERIOD: Last ca. 8 kyr. MAJOR TAXA STUDIED: Eucalyptus sensu lato, Leptospermum and Casuarinaceae. METHODS: High‐resolution pollen and charcoal analyses were undertaken on a ca. 8 kyr sediment record and compared with an independent quantitative precipitation reconstruction inferred from leaf carbon isotopes from the same site. We performed Principal Component Analysis to extract the main vegetation trends around Swallow Lagoon. We then compared vegetation changes to local charcoal records to understand the climate‐vegetation‐fire relationships under different rainfall regimes. The trends in pollen, charcoal and rainfall were analysed using Generalized Additive Models and wavelet coherence. RESULTS: Relatively high Casuarinaceae pollen abundance and high charcoal influx were found prior to 3.4 ka, during a phase of high rainfall. Between 3.4 and 1.5 ka there was an increase in Leptospermum‐type pollen abundance in concert with a decline in both rainfall and charcoal influx. After 1.5 ka low rainfall was generally maintained and a significant increase in Eucalyptus was detected, along with an increase in microscopic charcoal. MAIN CONCLUSIONS: Our study, from a sclerophyll forest setting that is typical of ~30% of Australia's vegetation, provides a unique example of complex climate‐biomass‐fire feedbacks and highlights biomass limitation of fire activity. High rainfall at Swallow Lagoon is linked to dense Casuarinaceae‐dominated forests and high fire activity prior to 3.4 ka. Between 3.4 and 1.5 ka, a decline in rainfall leads to reduced biomass burning during a phase dominated by shrub communities. After 1.5 ka, a change in fuel type was related to a transition to an open eucalypt forest and greater microscopic charcoal influx.