79 research outputs found
Tsunami threat in the Indian Ocean from a future megathrust earthquake west of Sumatra
No full textAbstract not availableJohn McCloskey, Andrea Antonioli, Alessio Piatanesi, Kerry Sieh, Sandy Steacy, Suleyman Nalbant, Massimo Cocco, Carlo Giunchi, JianDong Huang, Paul Dunlo
Interseismic coupling, stress evolution, and earthquake slip on the Sunda megathrust
No full textThe extent to which interseismic coupling controls the slip distribution of large megathrust earthquakes is unclear, with some authors proposing that it is the primary control and others suggesting that stress changes from previous earthquakes are of first-order importance. Here, we develop a detailed stress history of the Sunda megathrust, modified by coupling, and compare the correlation between slip and stress with that of slip versus coupling. We find that the slip distributions of recent earthquakes are more consistent with the stress field than with the coupling distributions but observe that in places, the stress pattern is strongly dependent on poorly constrained values of slip in historical earthquakes. We also find that of the 13 earthquakes in our study for which we have hypocentral locations, only two appear to have nucleated in areas of negative stress, and these locations correspond to large uncertainties in the slip distribution of pre-instrumental events.Suleyman Nalbant, John McCloskey, Sandy Steacy, Mairead NicBhloscaidh, and Shane Murph
A Hybrid ETAS‐Coulomb Approach to Forecast Spatiotemporal Aftershock Rates
No full textAftershock sequences are an ideal testing ground for operational earthquake forecasting models as they contain relatively large numbers of earthquakes clustered in time and space. To date, most successful forecast models have been statistical, building on empirical observations of aftershock decay with time and earthquake size frequency distributions. Another approach is to include Coulomb stress changes from the mainshock which influence the spatial location of the aftershocks although these models have generally not performed as well as the statistical ones. Here we develop a new hybrid Epidemic‐Type Aftershock Sequence (ETAS)/Coulomb model which attempts to overcome the limitations of its predecessors by redistributing forecast rate from negatively to positively stressed regions based on observations in the model learning period of the percentage of events occurring in those positively stressed regions. We test this model against the 1992 Landers aftershock sequence using three different ETAS kernels and five different models for slip in the Landers earthquake. We also consider two variations of rate redistribution, one based on a fixed value and the other variable depending on the percentage of aftershocks observed in positively stressed Coulomb regions during the learning period. We find that the latter model performs at least as well as ETAS on its own in all tests and better than ETAS in 14 of 15 tests in which we forecast successive 24‐hr periods. Our results suggest that including Coulomb stress changes can improve operational earthquake forecasting models.T. Reverso, S. Steacy, D. Marsa
A tale of two disasters: biases in risk communication
No full textTheme for 2016: Recognizing and representing eventsRisk communication, where scientists inform policy-makers
or the populace of the probability and magnitude of possible
disasters, is essential to disaster management – enabling
people to make better decisions regarding preventative steps,
evacuations, etc. Psychological research, however, has
identified multiple biases that can affect people’s
interpretation of probabilities and thus risk. For example,
availability (Tversky & Kahneman, 1973) is known to
confound probability estimates while the descriptionexperience
gap (D-E Gap) (Hertwig & Erev, 2009) shows low
probability events being over-weighted when described and
under-weighted when learnt from laboratory tasks. This paper
examines how probability descriptions interact with real
world experience of events. Responses from 294 participants
across 8 conditions showed that people’s responses, given the
same described probabilities and consequences, were altered
by their familiarity with the disaster (bushfire vs earthquake)
and its salience to them personally. The implications of this
for risk communication are discussed.Matthew B. Welsh, Sandy Steacy, Steve H. Begg, Daniel J. Navarr
Stress triggering and the Canterbury earthquake sequence
No full textThe Canterbury earthquake sequence, which includes the devastating Christchurch event of 2011 February, has to date led to losses of around 40 billion NZ dollars. The location and severity of the earthquakes was a surprise to most inhabitants as the seismic hazard model was dominated by an expected Mw > 8 earthquake on the Alpine fault and an Mw 7.5 earthquake on the Porters Pass fault, 150 and 80km to the west of Christchurch. The sequence to date has included an Mw = 7.1 earthquake and 3 Mw >/= 5.9 events which migrated from west to east. Here we investigate whether the later events are consistent with stress triggering and whether a simple stress map produced shortly after the first earthquake would have accurately indicated the regions where the subsequent activity occurred. We find that 100 percent of M > 5.5 earthquakes occurred in positive stress areas computed using a slip model for the first event that was available within 10 d of its occurrence. We further find that the stress changes at the starting points of major slip patches of post-Darfield main events are consistent with triggering although this is not always true at the hypocentral locations. Our results suggest that Coulomb stress changes contributed to the evolution of the Canterbury sequence and we note additional areas of increased stress in the Christchurch region and on the Porters Pass fault.Sandy Steacy, Abigail Jimenez and Caroline Holde
Ex-ante evaluation of tightening environmental policy: the case of mineral use in Dutch agriculture
No full textNon-point source pollution is notoriously difficult to asses. A relevant example is mineral emissions in the Netherlands. Since the mid 1980s the Dutch government has sought to reduce emissions through a wide variety of measures, the effect of which in turn is monitored using modeling techniques. This paper presents the current generation of mineral emission models from agriculture based on microsimulation of farms in combination with a spatial equilibrium model for the dispersion of manure from excess regions with high livestock intensities within the country to areas with low livestock intensities. The micro-simulation approach retains the richness in the heterogeneity of farm household decision making that are the core cause of the difficulty of assessing non-point source pollution, while using the best available data to track corresponding pollution. Using scenario analysis we are able to assess the possible effects of further tightening of agro-environmental policy.micro-simulation, spatial-equilibrium model, non-point source pollution, Environmental Economics and Policy,
Camosun Showcase 2019: Professional, Scholarly & Creative Activity
No full textCamosun College values lifelong learning and faculty development. The faculty stories in this report highlight how the college enables development through scheduled development time, professional development funds, innovation and creativity grants and the supports provided by the Centre of Excellence for Teaching and Learning.Published in 2019 and released at the May 2, 2019 Walls Optional Conference. Faculty profiled in this report include: Corrine Michel & Dan Reeve; Applied Learning & Political Science Department.
Richard Burman, Applied Research.
Tommy Happynook, Indigenous Education & Community Connections.
Todd Ormiston, Indigenous Education & Community Connections.
Laura Hadwin, English Language Development Department.
John G. Boehme, Visual Arts Department.
Nicole Kilburn & Tara Tudor, Anthropology Department.
Ken Steacy & Joan Steacy, Communications Department, Comics & Graphic Novels.
Nancy Yakimoski, Visual Arts Department.
Carl Everitt, Tourism, Hospitality & Golf Management.
Elizabeth Morch, Dental Department, Dental Hygiene Program.
Sandra Carr, Fine Furniture/Joinery Program.
Dawn Smith, Centre for Excellence in Teaching & Learning (CETL).
Scott Kouri, Counselling Department.
Michael Borins, Mandy Hayre, & John Lee; Centre for Accessible Learning, Dental Hygiene Department, Chemistry and Geoscience Department
Elizabeth West, English Language Development Department, Centre for Excellence in Teaching & Learning
Messages from Sherri Bell, Camosun President and Sybil Harrison, Director of Learning Services are also featured. Cover art, "Blue on Black," by Nancy Yakimoski, Visual Arts Department
A new hybrid Coulomb/statistical model for forecasting aftershock rates
No full textFirst published online: November 11, 2013Forecasting the spatial and temporal distribution of aftershocks is of great importance to earthquake scientists, civil protection authorities and the general public as these events cause disproportionate damage and consternation relative to their size. At present, there are two main approaches to such forecasts—purely statistical methods based on observations of the initial portions of aftershock sequences and a physics-based approach based on Coulomb stress changes caused by the main shock. Here we develop a new method which combines the spatial constraints from the Coulomb model with the statistical power of the STEP (short-term earthquake probability) approach. We test this pseudo prospectively and retrospectively on the Canterbury sequence against the STEP model and a Coulomb rate–state method, using data from the first 10 d following each main event to forecast the rate of M ≥ 4 events in the following 100 d. We find that in retrospective tests the new model outperforms STEP for two events in the sequence but this is not the case for pseudo-prospective tests. Further, the Coulomb rate–state approach never performs better than STEP. Our results suggest that incorporating the physical constraints from Coulomb stress changes can increase the forecasting power of statistical models and clearly show the importance of good data quality if prospective forecasts are to be implemented in practice.Sandy Steacy, Matt Gerstenberger, Charles Williams, David Rhoades and Annemarie Christopherse
Simulating Seismicity in a Fault Network Model: the Effect of Interaction on Event Statistics
No full textSimulating Seismicity in a Fault Network Model: the Effect of Interaction on Event StatisticsIstituto Nazionale di Geofisica e Vulcanologia (INGV), Rome, Italy
Institute of Statistical Mathematics (ISM), Tokyo, Japan
Swiss Seismological Service, Institute of Geophysics (ETH), Zürich, SwitzerlandUnpublishedErice, Italyope
Indonesian earthquake: Earthquake risk from co-seismic stress
No full textFollowing the massive loss of life caused by the Sumatra-Andaman earthquake in Indonesia and its tsunami, the possibility of a triggered earthquake on the contiguous Sunda trench subduction zone is a real concern. We have calculated the distributions of co-seismic stress on this zone, as well as on the neighbouring, vertical strike-slip Sumatra fault, and find an increase in stress on both structures that significantly boosts the already considerable earthquake hazard posed by them. In particular, the increased potential for a large subduction-zone event in this region, with the concomitant risk of another tsunami, makes the need for a tsunami warning system in the Indian Ocean all the more urgent.John McCloskey, Suleyman S.Nalbant, Sandy Steac
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