MATRIX Reference Reports

The Multi-HAzard and MulTi-RIsK Assessment MethodS for Europe or MATRIX project (01.10.2010 to 31.12.2013), coordinated by the GFZ, set out to tackle some of the issues associated with multi-hazard and risk assessment. Disaster risk reduction (DDR) activities generally treat different natural hazards and their associated risks separately within what may be termed a "single-type" approach. However, this ignores the spatial and temporal interactions that often arise along the disaster risk chain. For instance, one hazardous event may trigger others, e.g., earthquakes causing tsunamis, or several different types may occur concurrently, e.g., severe weather and earthquakes. Considering vulnerability, an initial event would leave a community more susceptible to future, possibly different, hazards, e.g., an earthquake weakening buildings which are damaged further by windstorms. The temporal dimension may include changes in exposure, e.g., increased urbanisation, altering the total risk to an area, while repeated events lessen a community's resilience. Meanwhile, although losses are estimated by usually only considering direct economic losses or casualties, this ignores less tangible losses such as reduced business activity or the loss of cultural heritage. In short, the total risk estimated when incorporating interactions between multiple hazards and risks is likely to be greater than the sum of the individual parts. Hence, for a more comprehensive risk assessment paradigm, these, and other, interactions need to be considered. Therefore, MATRIX set out to develop concepts, methods, frameworks and tools for dealing with risk assessment within a multi-hazard and risk environment. The focus was on the hazards that most affect Europe, namely earthquakes, landslides, volcanos, tsunamis, wild fires, storms and fluvial and coastal flooding. Interactions at all the different levels were considered, such as cascading events and time dependency in vulnerability. The resulting products were applied at three test cases: Naples, Italy, the French West Indies, and Cologne, Germany. Considerable interaction with end-users was also undertaken, including identifying biases at the individual and institutional level which may hinder employing a multi-type framework for risk governance. This Scientific Technical Report presents two so-called "Reference reports" produced during the MATRIX project. These reports were provided to the European Commission as deliverables, namely D8.4 "MATRIX Results I and Reference Report" and D8.5 "MATRIX Results II and Reference Report". D8.4 presented a series of specific reports outlining the results of the project, written in a manner accessible not only to the specialist but with a broader audience in mind. D8.5 deals with the risk governance within a multi-hazard and risk context and has since been published. We therefore divide with document in two, where part 1 represented the outcomes presented in D8.4 while D8.5 forms part 2. We believe the MATRIX project was a very important step towards the goal of establishing the multi-hazard and risk environment as the norm within a European context, and we hope that the reader will benefit from the results presented here

The Mw = 6.3, November 21, 2004, Les Saintes earthquake (Guadeloupe): Tectonic setting, slip model and static stress changes,

International audienceOn November 21, 2004, a magnitude 6.3 earthquake occurred offshore, 10 km south of Les Saintes archipelago in Guadeloupe (French West Indies). There were more than 30000 aftershocks recorded in the following two years, most of them at shallow depth near the islands of the archipelago. The main shock and its main aftershock of February 14, 2005 (Mw = 5.8) ruptured a NE-dipping normal fault (Roseau fault), mapped and identified as active from high-resolution bathymetric data a few years before. This fault belongs to an arc-parallel en echelon fault system that follows the inner edge of the northern part of the Lesser Antilles arc, accommodating the sinistral component of oblique convergence between the North American and Caribbean plates. The distribution of aftershocks and damage (destruction and landslides) are consistent with the main fault plane location and attitude. The slip model of the main shock, obtained by inverting jointly global broadband and local strong motion records, is characterized by two main slip zones located 5 to 10 km to the SE and NW of the hypocenter. The main shock is shown to have increased the Coulomb stress at the tips of the ruptured plane by more than 4 bars where most of the aftershocks occurred, implying that failures on fault system were mainly promoted by static stress changes. The earthquake also had an effect on volcanic activity since the Boiling Lake in Dominica drained twice, probably as a result of the extensional strain induced by the earthquake and its main aftershock

Social and institutional barriers to effective multi-hazard and multi-risk decision making and governance

Policies and decisions for mitigating and adapting to hazards are not taken in a hypothetical world populated by rational actors free of institutional incentives, but rather in an institutional context marked by divisions of responsibility, poor communication pathways, and at times conflicting objectives. Indeed these factors could create a particular burden on the use of multiple-hazards assessment, since it may requre the cooperation of multiple agencies. This task will focus analysis on one or two of the real-world test cases, in order to appraise the institutional landscape for mitigation and adaptation, find the barriers, and suggest solutions. It will rely on a desk analysis of legal and regulatory documents, leading into stakeholder interviews and surveys. This will require multiple visits to up to two of the case study sites, in order to meet with key policy-makers and decision-makers. A final workshop held in each site will serve first to validate the findings from the desk study and stakeholder interviews, and second to identify robust pathways for modifying the institutional landscape to overcome the current barriers

Comparing predicted and observed ground motions from subduction earthquakes in the Lesser Antilles

This brief article presents a quantitative analysis of the ability of eight published empirical ground-motion prediction equations (GMPEs) for subduction earthquakes (interface and intraslab) to estimate observed earthquake ground motions on the islands of the Lesser Antilles (specifically Guadeloupe, Martinique, Trinidad, and Dominica). In total, over 300 records from 22 earthquakes from various seismic networks are used within the analysis. It is found that most of the GMPEs tested perform poorly, which is mainly due to a larger variability in the observed ground motions than predicted by the GMPEs, although two recent GMPEs derived using Japanese strong-motion data provide reasonably good predictions. Analyzing separately the interface and intraslab events does not significant modify the results. Therefore, it is concluded that seismic hazard assessments for this region should use a variety of GMPEs in order to capture this large epistemic uncertainty in earthquake ground-motion prediction for the Lesser Antilles.John Douglas, Rosemarie Mohai