ORCID Profile
0000-0002-5197-1742
Current Organisation
Geoscience Australia
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Publisher: Informa UK Limited
Date: 24-07-2019
Publisher: American Geophysical Union (AGU)
Date: 09-2022
DOI: 10.1029/2022TC007250
Abstract: Reverse faulting in Otago, southern New Zealand, accommodates distributed tectonic convergence on the eastern side of the Australian‐Pacific plate boundary. Paleoearthquake records from some of the faults in the region show highly variable earthquake recurrence times, with long periods of quiescence separated by periods of earthquake activity. Here we develop a longer‐term context for these records, using cosmogenic radionuclide dating of faulted alluvial fan surfaces to characterize the late Quaternary slip rates on two significant faults within the system, the Hyde and Dunstan faults. We determine an average slip rate of 0.24 mm/yr (0.19–0.29 mm/yr at 95% confidence) for the Hyde Fault since about 115 ka, and an average slip rate of 0.16 mm/yr (0.12–0.21 mm/yr) for the Dunstan Fault since about 320 ka. Both faults show increases in slip rate of a factor of three to five times the average long‐term rate over timescales of 10 kyr. Increases in slip rate are out of phase on the two faults, supporting a hypothesis that strain is shared within the fault system over timescales on the order of 10 kyr. Over longer timescales, on the order of 100 kyr, slip rates can be well‐approximated by a linear fit, providing an upper limit on the variability of fault slip rates with time.
Publisher: SAGE Publications
Date: 25-02-2020
Abstract: Seismic hazard assessments in stable continental regions such as Australia face considerable challenges compared with active tectonic regions. Long earthquake recurrence intervals relative to historical records make forecasting the magnitude, rates, and locations of future earthquakes difficult. Similarly, there are few recordings of strong ground motions from moderate-to-large earthquakes to inform development and selection of appropriate ground-motion models (GMMs). Through thorough treatment of these epistemic uncertainties, combined with major improvements to the earthquake catalog, a 2018 National Seismic Hazard Assessment (NSHA18) of Australia has been undertaken. The resulting hazard levels at the 10% in 50-year probability of exceedance level are in general significantly lower than previous assessments, including hazard factors used in the Australian earthquake loading standard ( AS 1170.4–2007 (R2018)), demonstrating our evolving understanding of seismic hazard in Australia. The key reasons for the decrease in seismic hazard factors are adjustments to catalog magnitudes for earthquakes in the early instrumental period, and the use of modern ground-motion attenuation models. This article summarizes the development of the NSHA18 explores uncertainties associated with the hazard model, and identifies the dominant factors driving the resulting changes in hazard compared with previous assessments.
Publisher: American Geophysical Union (AGU)
Date: 10-2020
DOI: 10.1029/2018TC005365
Publisher: American Geophysical Union (AGU)
Date: 14-11-2020
DOI: 10.1029/2020GL089272
Abstract: Elastic rebound theory forms the basis of the standard earthquake cycle model and predicts large earthquakes to recur regularly through cycles of strain accumulation and release. Yet few in idual earthquake records are sufficiently long to test the theory. Here we characterize the distribution of earthquake interevent times from a global compilation of 80 long‐term records. We find that large earthquakes recur more regularly than a random Poisson process on in idual fault segments. The majority of Earth's well‐studied faults shows weakly periodic and uncorrelated large earthquake recurrence, consistent with the expectations of elastic rebound theory. However, many low activity‐rate (annual occurrence rates 2 × 10 −4 ) faults show random or clustered earthquake recurrence, which cannot be explained by elastic rebound theory.
Publisher: American Geophysical Union (AGU)
Date: 12-2017
DOI: 10.1002/2017RG000579
Publisher: Author(s)
Date: 2017
DOI: 10.1063/1.4987104
Publisher: Copernicus GmbH
Date: 28-11-2014
DOI: 10.5194/NHESS-14-3105-2014
Abstract: Abstract. Probabilistic hazard assessments are a fundamental tool for assessing the threats posed by hazards to communities and are important for underpinning evidence-based decision-making regarding risk mitigation activities. Indonesia has been the focus of intense tsunami risk mitigation efforts following the 2004 Indian Ocean tsunami, but this has been largely concentrated on the Sunda Arc with little attention to other tsunami prone areas of the country such as eastern Indonesia. We present the first nationally consistent probabilistic tsunami hazard assessment (PTHA) for Indonesia. This assessment produces time-independent forecasts of tsunami hazards at the coast using data from tsunami generated by local, regional and distant earthquake sources. The methodology is based on the established monte carlo approach to probabilistic seismic hazard assessment (PSHA) and has been adapted to tsunami. We account for sources of epistemic and aleatory uncertainty in the analysis through the use of logic trees and s ling probability density functions. For short return periods (100 years) the highest tsunami hazard is the west coast of Sumatra, south coast of Java and the north coast of Papua. For longer return periods (500–2500 years), the tsunami hazard is highest along the Sunda Arc, reflecting the larger maximum magnitudes. The annual probability of experiencing a tsunami with a height of 0.5 m at the coast is greater than 10% for Sumatra, Java, the Sunda islands (Bali, Lombok, Flores, Sumba) and north Papua. The annual probability of experiencing a tsunami with a height of 3.0 m, which would cause significant inundation and fatalities, is 1–10% in Sumatra, Java, Bali, Lombok and north Papua, and 0.1–1% for north Sulawesi, Seram and Flores. The results of this national-scale hazard assessment provide evidence for disaster managers to prioritise regions for risk mitigation activities and/or more detailed hazard or risk assessment.
Publisher: Frontiers Media SA
Date: 30-06-2015
Publisher: SAGE Publications
Date: 27-03-2023
DOI: 10.1177/87552930231151977
Abstract: This article explores several area-based tests of long-term seismic hazard forecasts for the Australian continent. Using the observed seismicity, ShakeMaps are calculated for earthquakes that are expected to have generated moderate-to-high levels of ground shaking within continental Australia in the past 50 years (January 1972 through December 2021). A “composite ShakeMap” is generated that extracts the maximum peak ground acceleration “observed” in this 50-year period for any site within the continent. The fractional exceedance area of this composite map is compared with four generations of Australian seismic hazard maps for a 10% probability of exceedance in 50 years (~1/500 annual exceedance probability) developed since 1990. In general, all these models appear to forecast higher seismic hazard relative to the ground motions that are estimated to have occurred in the last 50 years, with the most recent hazard model yielding a fractional exceedance area most similar to the target 1/500 annual exceedance probability. The sensitivity of these results to various modeling assumptions was tested by exploring an alternative ground-motion characterization model that forecasts higher overall ground-shaking intensities. The sensitivity of these results is also tested with the interjection of a rare scenario earthquake with an expected regional recurrence of approximately 8700 years. While these area-based analyses do not provide a robust assessment of the performance of the candidate seismic hazard for any specific location given the limited independent data, they do provide—to the first order—a guide to the performance of the respective maps at a continental scale.
Publisher: Geological Society of London
Date: 26-04-2016
DOI: 10.1144/SP441.6
Publisher: Springer Science and Business Media LLC
Date: 09-08-2019
Publisher: Elsevier BV
Date: 06-2008
Publisher: Geological Society of London
Date: 02-06-2017
DOI: 10.1144/SP441.3
Publisher: Informa UK Limited
Date: 19-03-2023
Publisher: Informa UK Limited
Date: 22-11-2021
Publisher: Springer Science and Business Media LLC
Date: 02-03-2020
Publisher: Seismological Society of America (SSA)
Date: 11-12-2019
DOI: 10.1785/0120180085
Publisher: Springer Science and Business Media LLC
Date: 03-09-2019
No related grants have been discovered for Jonathan Griffin.