Paul Tregoning | The Australian National University (original) (raw)

Papers by Paul Tregoning

Geophysical Research Letters, 2011

Quaternary Science Reviews, 2016

Creating models of the Laurentide ice sheet is challenging, due to the deficiency of chronologica... more Creating models of the Laurentide ice sheet is challenging, due to the deficiency of chronological constraints and the uneven spatial resolution of data to determine the evolution of the glacio-isostatic response after deglaciation. Previous models relied on uncalibrated radiocarbon constrained margins that proved to have deficiencies in recent studies. Additionally, many recent Laurentide ice sheet models have been developed by incorporating climatic parameters that are poorly resolved for the late glacial period. We present a new ice sheet model by an iterative process of changing basal shear stress values and ice sheet margin location. A particular focus of this study is to determine the thickness and extent of the western Laurentide ice sheet, where there were few well dated observations of glacio-isostatic motion until recently. The volume of an ice sheet during long periods depends mostly on basal shear stress and margin position, which are the main parameters that we vary to ...

Australian Journal of Earth Sciences, 2012

Computers & Geosciences, 2013

Geophys Res Lett, 2005

Space-geodetic techniques can detect elastic deformation of the Earth caused by atmospheric press... more Space-geodetic techniques can detect elastic deformation of the Earth caused by atmospheric pressure loading (ATML). However, it has not yet been demonstrated whether these surface displacements should be accounted for at the time of reduction of the observations or by applying time-averaged values to the coordinates after the analysis of the observations. An analysis of the power spectral density of the ATML predicted vertical deformation shows that, aside from the diurnal and semi-diurnal periods, there is very little power in the sub-daily frequencies. The present tidal ATML models improve the analysis at sites near the equator but seem to degrade the height estimates elsewhere. The majority of the non-tidal deformation can be modelled by applying a daily-averaged correction to daily estimates of coordinates but a greater improvement in height RMS is found if non-tidal ATML is applied at the observation level.

Journal of Geophysical Research, 2005

Http Dx Doi Org 10 1080 08120099 2012 664828, Jun 1, 2012

Earth Planets and Space, 2000

Papua New Guinea is one of the most active tectonic regions in the world. It comprises several mi... more Papua New Guinea is one of the most active tectonic regions in the world. It comprises several microplates and deforming zones trapped in the collision of the Australian and Pacific Plates. GPS observations have been used to estimate plate velocities across a network of sites spanning most of the country. We present new velocites in the northwestern region of New Guinea, and look in detail at the strain accumulation region between the South Bismarck and Pacific Plates in the New Ireland/New Britain region.

Journal of Geophysical Research, 2009

The South West Seismic Zone (SWSZ) located in Western Australia, is an area of high intra-plate e... more The South West Seismic Zone (SWSZ) located in Western Australia, is an area of high intra-plate earthquake activity. The area is thought to pose significant seismic hazard since the SWSZ is near to the city of Perth, a population centre of 1.5 million people, and it encompasses the source area of the magnitude 6.8 Meckering earthquake of 1968. We have undertaken an analysis of interferometric satellite radar (InSAR) observations, from the ENVISAT satellite, of a seismically active area of the SWSZ. We have observed a shallow, 1 km depth, magnitude 4.4, reverse fault earthquake near the township of Kalannie. The earthquake generated maximum line-of-sight coseismic displacements of 28 mm, visible in both descending and ascending passes. We reduce atmospheric artifacts through a time series analysis of the InSAR data and develop an analysis strategy which deals with transient signal stability associated with agricultural activity in the study area. This is the first observation of a coseismic displacement field associated with an Australian earthquake using modern satellite geodetic tools. It provides important constraints on the earthquake hypocentre and source mechanism that can be used to calibrate techniques for determining earthquake magnitude and location that are used in routine earthquake monitoring of the SWSZ. We make a comparison of the InSAR determined earthquake mechanism to seismic observations of the event.

Journal of Geophysical Research Solid Earth, 2002

Using up to 11 years of data from a global network of Global Positioning System (GPS) stations, i... more Using up to 11 years of data from a global network of Global Positioning System (GPS) stations, including 12 stations well distributed across the Pacific Plate, we derive present-day Euler vectors for the Pacific Plate more precisely than has previously been possible from space geodetic data. After rejecting on statistical grounds the velocity of one station on each of the Pacific and North American plates, we find that the quality of fit of the horizontal velocities of 11 Pacific Plate (PA) stations to the best fitting PA Euler vector is similar to the fit of 11 Australian Plate (AU) velocities to the AU Euler vector and ˜20% better than the fit of nine North American Plate (NA) velocities to the NA Euler vector. The velocities of stations on the Pacific and Australian Plates each fit a rigid plate model with an RMS residual of 0.4 mm/yr, while the North American velocities fit a rigid plate model with an RMS velocity of 0.6 mm/yr. Our best fitting PA/AU relative Euler vector is located ˜170 km southeast of the NUVEL-1A pole but is not significantly different at the 95% confidence level. It is also close (<70 km in position and <3% in rate) to a pole derived from transform faults identified from satellite altimetry, suggesting that the vector has not changed significantly over the past 3 Myr. Our relative Euler vector is also consistent with all known geological and geodetic evidence concerning the AU/PA plate boundary through New Zealand. The GPS sites offshore of southern California are presently moving 4-5 ± 1 mm/yr relative to predicted Pacific velocity, with their residual velocities in approximately the opposite direction to PA/NA relative motion. Likewise, the easternmost sites in South Island, New Zealand, are moving ˜3 ± 1 mm/yr relative to predicted Pacific velocity, with the residuals in approximately the opposite direction to PA/AU relative motion. These velocity residuals are in the same sense as predicted by elastic strain accumulation on known plate boundary faults but are of a significantly higher magnitude in both southern California and New Zealand, implying that the plate boundary zones in both regions are wider than previously believed.

Geophysical Research Letters, Aug 7, 2009

International Association of Geodesy Symposia Fernando Sanso, Series Editor Symposium 101: Global... more International Association of Geodesy Symposia Fernando Sanso, Series Editor Symposium 101: Global and Regional Geodynamics Symposium 102: Global Positioning System: An Overview Symposium 103: Gravity, Gradiometry, and Gravimetry Symposium 104: Sea ...

The Indonesian archipelago encompasses a wide range of tectonic environments, including island ar... more The Indonesian archipelago encompasses a wide range of tectonic environments, including island arc volcanism, subduction zones, and arc-continent collision. Many of the details of this tectonic activity are still poorly understood, especially where the Australian continent collides with Indonesia, separating the Sunda Arc in west from that at the Banda Arc in the east. While it seems clear that the Australian plate is subducted under both the Sunda and Banda Arcs, it is not clear what happens along the 1000 km -long stretch in between. The question of just where the plate motion is accommodated is of major importance to assessments of earthquake and tsunami hazard in the region. To help resolve these questions the Geospatial Information Agency of Indonesia has collaborated with the Australian National University and the Bandung Institute of Technology in a GPS campaign spanning much of eastern Indonesia, from Lombok in the west to Alor in the east. We have combined these data with t...