Projects per year
Abstract / Description of output
According to a recent UN report, seismic risk from large earthquakes continues to increase globally in line with infrastructure and population increase in developing nations. This implies the vulnerability is not decreasing relative to increased exposure. Specific examples include recent devastating earthquakes in Haiti and Sumatra in areas of known seismic hazard, but clearly this is part of a much wider problem. Seismologists and engineers can play a key role in public engagement, in communicating known best practice to local planners and practitioners on appropriate mitigation strategies, and in fundamental research to quantify seismic hazard in a probabilistic way. All probabilistic hazard forecasts are subject to epistemic (systematic) and aleatory (statistical) uncertainty. To date it has been assumed that the major uncertainties in probabilistic seismic hazard analysis are due to uncertainties in ground motion attenuation. As new strong ground motion data become available, and site response is better characterized locally in advance of major earthquakes, this uncertainty will reduce. Here we address uncertainties arising from the first two steps in seismic hazard analysis by quantifying the effect of sampling bias and statistical error in earthquake recurrence rates from finite records of seismic sources. We find even simple parameters such as mean event rate converge to a central limit much more slowly than would be expected for a Gaussian process. The residuals in the frequencymagnitude distribution instead follow a Poisson distribution to a good approximation at all magnitudes. Finite temporal sampling of this slowlyconverging system has resulted in a bestfitting distribution for the global earthquake population that can be changed from a tapered GR law to a pure GR law by a single large event and its aftershocks. In regional studies of subduction zones it is currently not possible to reject the GR hypothesis in favour of the characteristic earthquake model within the Poisson error, even when visually a few extreme events appear as significant outliers on a log frequencymagnitude plot. The epistemic and aleatory uncertainties described here must be taken into account in assessing the skill of timedependent hazard models relative to the uncertainties in timeindependent models.
Original language  English 

Title of host publication  Applications of Statistics and Probability in Civil Engineering Proceedings of the 11th International Conference on Applications of Statistics and Probability in Civil Engineering 
Pages  735743 
Number of pages  9 
Publication status  Published  1 Jan 2011 
Fingerprint
Dive into the research topics of 'Model selection and uncertainty in earthquake hazard analysis'. Together they form a unique fingerprint.Projects
 1 Finished

TRIGS: Triggering instabilities in materials and geosystems
Zaiser, M. & Main, I.
1/01/07 → 31/12/09
Project: Research
Research output
 1 Editorial

Community Online Resource for Statistical Seismicity Analysis
CORSSA Working Grp, Zechar, J. D., Hardebeck, J. L., Michael, A. J., Naylor, M., Steacy, S., Wiemer, S. & Zhuang, J., 2011, In: Seismological Research Letters. 82, 5, p. 686690 5 p.Research output: Contribution to journal › Editorial › peerreview