50thKaikoura05 -1- Kaikoura 2005 CHARACTERISATION OF NEW ...

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determine a record of secular variation and paleointensity for New Zealand, and for an environmental magnetic study of the Waipaoa Catchment. Records of inclination of the geomagnetic field, NRM intensity and magnetic susceptibility are presented. Samples have low NRM intensities (10 -6 –10 -5 A/m) and similar mean destructive fields (MDF ~40mT), which indicate that the magnetic minerals have a fine grain size, are magnetically soft and easily demagnetised. IRM measurements indicate magnetite is the major magnetic mineral present in the cores. The prognosis for paleomagnetic applications to environmental and magnetic field studies is good as is the potential for the development of a highresolution paleomagnetic age model for the cores. Samples are generally well behaved, with sufficient magnetic intensity and variations in inclination and magnetic susceptibility. NRM intensities appear to provide reliable estimates of relative paleointensity and variations in magnetic grain size, concentrations of magnetic grains and magnetic minerals are jointly indicated by �, MDF, ARM and IRM. POSTER THE OFFSHORE MORPHO-STRUCTURE OF THE SOUTHEASTERN VITI LEVU SEISMIC SOURCE REGION, FIJI Tariq Rahiman & Jarg Pettinga Dept. of Geological Sciences, University of Canterbury, P.B. 4800, Christchurch (t.rahiman*geol.canterbury.ac.nz) SE Viti Levu is a seismically active intra-plate region of Fiji. The city of Suva (pop. ~150 000), in the SE coast of Viti Levu is vulnerable to the effects of potential offshore earthquakes and associated seismic hazards. Recently acquired SeaBat multibeam bathymetry and high resolution seismic reflection data reveals for the first time the physiography of the marginal slope of SE Viti Levu in unprecedented detail. The marginal slope is divided into five morphological domains, which are primarily influenced by the underlying geology and structure, and sedimentation from terrestrial sources. The eastern slope, an area between 178.2 and 178.4 E longitude and 18.2 and 18.4 S latitude, has had added influence from active tectonic processes and seismicity. The surface of this slope is scarred by linear submarine canyons, which are the surface expressions of faulted grabens. These submarine canyon faults extend onshore as fault valleys and structural lineaments and they collectively define continuous onshore/offshore fault zones. These fault zones form a complex network of faults, through which mesh style coseismic faulting is responsible for the diffused pattern of observed seismicity. The submarine canyons are relict features from the Late Miocene/Early Pliocene that have developed primarily by downslope erosional processes. They have experienced several episodes of re-incision and infilling events, the latest occurring during the late Pleistocene period of lowered sea level and subsequent marine transgression. Presently, headward erosion of the canyons into the marginal shelf is occurring by seismically triggered basinward sliding of masses at the canyon heads. The head of these canyons indent the marginal shelf and they coincide with deep water passages that segment the barrier coral reefs protecting the inner lagoon and coastline. The canyon heads are positioned to act as sinks for the coastal sediment transport system. Steep slopes of the canyon heads are only marginally stable due to rapid deposition of carbonate sediments from the barrier reef fronts and outflowing lagoonal sediments through the reef passages. Slope instability is exacerbated here by slope oversteepening and undercutting by canyon currents. Submarine landslides at the canyon heads are initiated primarily by periodic short term stresses generated by earthquakes, which have induced destructive local tsunami in the past. The canyon heads, all of which are within 5 km of the coast, are potential local tsunami source areas that pose a substantial threat to the coast. POSTER NUMERICAL MODELLING OF SUBMARINE LANDSLIDE TSUNAMI AND THE LOCAL TSUNAMI HAZARD OF SUVA CITY, FIJI Tariq Rahiman 1 , Jarg Pettinga 1 & Phil Watts 2 1 Dept. of Geological Sciences, University of Canterbury, P.B. 4800, Christchurch 2 Applied Fluids Engineering, Inc., Long Beach, California (t.rahiman*geol.canterbury.ac.nz) An important aspect of tsunami hazard assessment and mitigation is to produce predictive simulations of tsunami generation, propagation and run-up. Such simulations require accurate geological data on tsunami sources and a high quality computational grid, which is preferably based on high resolution bathymetry data. Predictive models used for simulations need to be tested and proven by running successful historical case studies. With a complete range of critical input datasets required for running predictive simulations, the coastal city of Suva in Fiji, provides a rare opportunity for assessing the tsunami hazard potential of submarine landslides. Suva City has experienced damaging historical earthquakes and associated submarine 50 th Kaikoura05 -72- Kaikoura 2005
landslide tsunami in the past. Recently acquired high resolution Reson SeaBat 8160 multi-beam bathymetry shows in unprecedented detail the locations and geometries of large slope failure scars off the coast of Suva. The destructive tsunami which followed the 1953 Suva earthquake provides a well documented account of a previous submarine landslide tsunami in the Suva area. Run-up data and arrival times from this event provide a benchmark for predictive models when creating tsunami hazard scenarios for Suva. Using high resolution bathymetry data and historical records we define the source of the 1953 Suva tsunami as a ~3 x 10 6 m 3 submarine landslide at the head of the Suva Canyon, located 5 km SW of Suva. Geometrical parameters from this submarine landslide are used in the TOPICS/GEOWAVE tsunami initialisation and propagation model to successfully simulate observed run-ups and arrival times of the 1953 Suva tsunami at eight different locations along the coast of Suva and nearshore islands. The computational grid used in this simulation was adjusted to low tide to simulate sea level during the 1953 event. The bathymetry data shows that the submarine landslide of 1953 is one of several failures that has occurred in this part of the Suva Canyon head in the past. These slope failures form a large retrogressive failure system that has been indenting the outer edge of the coral barrier reef. Two coral limestone boulder zones mapped on the reef crest represent tsunami deposits from the last two tsunami generating submarine landslides from this slope failure system. A set of curved fractures mapped on the barrier reef behind the headscarp of the 1953 failure is an indication of the likelihood of the next failure event and ensuing tsunami that will occur at this site. A predictive simulation of this future slope failure event was done using the source parameters similar to the 1953 landslide and with the computational grid adjusted to represent high tide, a potentially worse case scenario. The results of this simulationshowmaximumverticalrun-upupto4 m and maximum horizontal inundation up to 400 m at the Suva coast. ORAL GNS PALEONTOLOGICAL DATABASES PROGRAMME J.I. Raine, J.S. Crampton, E.M. Crouch, I. Matcham & B. Morrison GNS Science, PO Box 30368, Lower Hutt. (i.raine*gns.cri.nz) The New Zealand government, via FRST, recently increased available funding for designated Nationally Significant Databases and Collections, including the NZ Fossil Record File database (FRED) and the National Paleontological Collection (NPC). This has enabled GNS to set up, for the first time in the current funding regime, an explicit paleontological databases programme - formerly these activities were supported either through GNS's own resources or as small components of other FRST programmes. Aims of the new programme are to 1) develop and maintain comprehensive computer databases of fossil localities, collections, identifications, and paleontological interpretations; 2) provide easily accessible and useable database interfaces with extensive search and retrieval capabilities; and 3) attract routine participation (data provision and retrieval) by New Zealand and overseas researchers. The NPC was initiated in 1865 by the Colonial Museum, and subsequently passed to the NZ Geological Survey and its successor, GNS. Collections represent over 55,000 localities, primarily from the NZ mainland, offshore islands, and submarine cores and dredgings from the NZ region. There are also important holdings from Antarctica and the SW Pacific, and global-scope reference collections of fossil and modern species. Collections include the gamut of animal, plant and trace fossils from Ordovician to Recent, but the main strengths are in macrofossil invertebrates, protist microfossils, and plant macrofossils and palynomorphs. Most NPC identifications are databased in FRED, but we plan to computerise physical collection records, type catalogues, etc. to streamline maintenance and extend the use of the collections. Much of the data will be publicly available online, and we also plan to make the facility and software available for use by other NZ institutions or individuals. Over the last few years FRED has been transferred to a new database platform, with public Internet access for basic search and retrieval [http://data.gns.cri.nz/fred/]. This has been a challenging process, and further development of data entry and retrieval interfaces is planned within the new programme. New capabilities will include locality and fossil images, and sophisticated data manipulations (e.g., for research into biodiversity and statistical biostratigraphy). Following GNS- GSNZ consultation in May 2005, online registration of new localities, with continued participation of regional masterfile centres, is about to begin and this should ensure that new data is fed directly into the database. The backlog of existing locality records not yet in FRED will also be systematically entered through the new programme. Within the programme we will also maintain and develop associated databases, such as the existing NZ Stratigraphic Lexicon [http://data.gns.cri.nz/stratlex/], and taxonomyoriented databases such as the recently released NZ 50 th Kaikoura05 -73- Kaikoura 2005
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CHARACTERISATION OF NEW ZEALAND NEP
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myrtaceous. One 20 mm diameter flow
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ange of lower resolution or fragmen
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CRETACEOUS-EOCENE TRANSGRESSION MAR
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consists of a well-developed canyon
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model. The relative position of the
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converts to plate theory. Thus, the
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and on the following morning the mi
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the LGM grass peak. This period of
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offshore west coast to offshore eas
Page 21 and 22: 4 Institut de Recherche pour le Dé
Page 23 and 24: VEGETATION AND CLIMATE CHANGE AT TH
Page 25 and 26: wider range. The youngest layer has
Page 27 and 28: few normal faults visible especiall
Page 29 and 30: TRACKING CRUSTAL DIFFERENTIATION AN
Page 31 and 32: EMPIRICAL SCALING RELATIONS FOR SEI
Page 33 and 34: hydrovolcanic eruptions then took p
Page 35 and 36: and that the MTL marks a Late Carbo
Page 37 and 38: faunal changes within these cores w
Page 39 and 40: material at subsurface depths of se
Page 41 and 42: survived through in low numbers in
Page 43 and 44: in the TVZ and southern Havre Troug
Page 45 and 46: Tephra beds are commonly used to ai
Page 47 and 48: The MCC is bounded by deep-seated t
Page 49 and 50: distal alluvial plains where large
Page 51 and 52: Many of the molluscs in the highly
Page 53 and 54: incremental slip history and paleoe
Page 55 and 56: This paper explores what we know of
Page 57 and 58: volcanism and a linear vent oriente
Page 59 and 60: These areas are also described in
Page 61 and 62: 3D IMAGING OF THE FORE- AND BACKTHR
Page 63 and 64: ascending methane fluids/gases of p
Page 65 and 66: THE GRIFFENS ROAD TEPHRAS: VALUABLE
Page 67 and 68: sideritic concretions that occur in
Page 69 and 70: with 63.8%, and then [3] with 49.9%
Page 71: U-Th-Ra disequilibria data. In part
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Page 77 and 78: truncating three plutonic suites of
Page 79 and 80: active, andesitic White Island volc
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Page 83 and 84: oundaries and with immature source
Page 85 and 86: The new era of commercial viability
Page 87 and 88: TECTONICS OF THE GALATEA BASIN USIN
Page 89 and 90: performed by the electron backscatt
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Page 93 and 94: Most of the tectonic blocks in the
Page 95 and 96: TECTONIC AND NON-TECTONIC CAUSES OF
Page 97 and 98: The continental shelf of the Povert
Page 99 and 100: 5 Dept. of Mineral Sciences, Smiths
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