CRUST: Cascading Risk and Uncertainty assessment of earthquake Shaking and Tsunami

CRUST takes advantage of the UK's leadership in uncertainty evaluation of earthquake source and ground motion (Goda [PI] and University of Bristol/Cabot Research Institute) and on-shore tsunami impact research (Rossetto [Co-I] and University College of London/EPICentre [Earthquake and People Interaction Centre]) to develop an innovative cross-hazard risk assessment methodology for cascading disasters that promotes dynamic decision-making processes for catastrophe risk management. It cuts across multiple academic fields, i.e. geophysics, engineering seismology, earthquake engineering, and coastal engineering. The timeliness and critical needs for cascading multi-hazards impact assessments have been exemplified by recent catastrophes. CRUST fills the current gap between quasi-static, fragmented approaches for multi-hazards and envisaged, dynamic, coherent frameworks for cascading hazards.
CRUST combines a wide range of state-of-the-art hazard and risk models into a comprehensive methodology by taking into account uncertainty associated with predictions of hazards and risks. The work will provide multi-hazards risk assessment guidelines and tools for policy-makers and engineering/reinsurance industries. The proposal capitalises on a breakthrough technology for generating long-waves achieved by Rossetto. CRUST is composed of four work packages (WPs): WP1-'Ground shaking risk modelling due to mega-thrust subduction earthquakes'; WP2-'Tsunami wave and fragility modelling due to mega-thrust subduction earthquakes'; WP3-'Integrated multi-hazards modelling for earthquake shaking and tsunami'; and WP4-'Case studies for the Hikurangi and Cascadia subduction zones'. In WP1-WP3, the research adopts the 2011 Tohoku earthquake as a case study site, since this event offers extensive datasets for strong motion data, tsunami inundation, and building damage survey results, together with other geographical and demographical information (e.g. high-resolution bathymetry data and digital elevation model). The aims of WP1 are: to generate strong motion time-histories based on uncertain earthquake slips, reflecting multiple asperities (large slip patches) over a fault plane (WP1-1); to characterise spatiotemporal occurrence of aftershocks using global catalogues of subduction earthquakes (WP1-2); and to conduct probabilistic seismic performance assessment of structures subjected to mainshock-aftershock sequences (WP1-3). WP2 comprises tsunami wave profile and inundation simulation using uncertain earthquake slips (WP2-1); characterisation of tsunami loads to structures in coastal areas through large-scale physical experiments using an innovative long wave generation system at HR Wallingford (WP2-2); and development of analytical tsunami fragility models in comparison with field observations and experiments (WP2-3). The WP2 will be conducted in collaboration with academic collaborators from Kyoto University and Tohoku University (Japan). WP3 integrates the model components developed from WP1 and WP2 into a comprehensive framework for multi-hazards risk assessment for the 2011 Tohoku earthquake and tsunami (WP3-1). Then, practical engineering tools for the multi-hazards method will be developed in WP3-2. Finally, in WP4, the developed multi-hazards methodology will be applied to the Hikurangi and Cascadia subduction zones. The assessments are done in a predictive mode, and these case studies will be conducted in close collaboration with academic partners, GNS Science (New Zealand) for the Hikurangi zone, and researchers at Western University and University of British Columbia (Canada) for the Cascadia zone.

The targeted impact beneficiaries of the CRUST research are: (1) academics, (2) policy-makers responsible for DRR actions, and (3) industries (civil engineering and insurance/reinsurance).
New developments of scientific models/tools (e.g. stochastic slip models and large-scale tsunami testing) and integrating various state-of-the-art models (e.g. asperity-based strong motion simulation and analytical tsunami fragility) into a comprehensive framework are academically intriguing. This will stimulate further innovations by the CRUST investigators and other researchers. To maximise the impact of the CRUST project, results will be disseminated in high-quality journals and presentations at high-profile conferences. As part of such networking activities, a blind test competition will be launched at the 2015 International Tsunami Symposium, in which participants will be invited to make numerical predictions of tsunami flow characteristics (e.g. height and velocity) acting on a model structure in a flume at HR Wallingford. This event is intended to make strong connections with other leading researchers. These relationships at other conferences/meetings will be consolidated to create future research opportunities.
Expanding temporal aspects of the cascading hazard process promotes time-dependent risk management actions for evacuation and post-disaster recovery phases. For instance, risks from mainshock, tsunami, aftershocks, and combination of those together with their uncertainties can be quantified using the CRUST methodology. This will facilitate the robust design of vertical evacuation buildings and coastal defence structures in different environments. Such information should be integrated into engineering design, evacuation planning, and warning protocols within a community. CRUST will transform the current disintegrated hazard assessments and DRR measures into more coherent, forward-looking and dynamic systems. Potential social and economic benefits of this change can be enormous by saving lives, reducing losses, and creating sustainable communities by turning research investment in the low millions to DRR benefits in the billions.
The science-led CRUST research on cascading hazard modelling, validated based on novel experimental tests, numerical models, and extensive instrumental and field data, will benefit industrial partners and more broadly UK engineering and reinsurance industries. The outcomes of the project will be materialised as a set of guidelines for assessing the structural integrity of infrastructure due to compounding risks of multiple hazards. This is valuable for establishing next-generation of building standards in designing and assessing coastal infrastructure at risk of being subjected to extreme waves, aiding the UK civil engineering sector to bid for coastal management contracts both in the UK and abroad. The CRUST project will be able to offer a new set of industry standard analysis tools for assessing ground shaking and tsunami impacts on structures, which achieves more accurate estimation of seismic and tsunami risk exposure of insurance portfolios in coastal regions.
Finally, effective knowledge transfer from academia to practitioners both nationally and internationally is a major component of the project. To reach a broad range of audiences, a CRUST advisory group is formed. The board members have diverse backgrounds, spanning from the academic sector, civil engineering sector, catastrophe risk modelling sector, reinsurance sector, and DRR/science-public outreach sector. In addition, outreach activities will be carried out through the Cabot-CREDIBLE summer school, which will provide immediate links to key industrial players in the UK. The ultimate goal in this regard is to create vibrant industrial and academic communities for multi-hazards modelling. Taking the leadership in this new, emerging multidisciplinary field will be rewarding and have a long-term impact.