The role of science in physical natural hazard assessment : report to the UK Government by the Natural Hazard Working Group

Following the tragic Asian tsunami on 26 December 2004, the Prime Minister asked the Government’s Chief Scientific Adviser, Sir David King, to convene a group of experts (the Natural Hazard Working Group) to advise on the mechanisms that could and should be established for the detection and early warning of global physical natural hazards. 2. The Group was asked to examine physical hazards which have high global or regional impact and for which an appropriate early warning system could be put in place. It was also asked to consider the global natural hazard frameworks currently in place and under development and their effectiveness in using scientific evidence; to consider whether there is an existing appropriate international body to pull together the international science community to advise governments on the systems that need to be put in place, and to advise on research needed to fill current gaps in knowledge. The Group was asked to make recommendations on whether a new body was needed, or whether other arrangements would be more effective

Stochastic Stick - Slip Model Linking Crustal Shear Strength and Earthquake Interevent Times

The current understanding of the earthquake interevent times distribution (ITD) is incomplete. The Weibull distribution is often used to model the earthquake ITD. We link the earthquake ITD on single faults with the Earth's crustal shear strength distribution by means of a phenomenological stick - slip model. We obtain Weibull ITD for power-law stress accumulation, i.e., $\sigma(t) = \alpha t^{\beta}$, where $\beta >0$ for single faults or systems with homogeneous strength statistics. We show that logarithmic stress accumulation leads to the log-Weibull ITD. For the Weibull ITD, we prove that (i) $m= \beta m_s$, where $m$ and $m_s$ are, respectively, the ITD and crustal shear strength Weibull moduli and (ii) the time scale $\tau_s = (S_s/\alpha)^{1/\beta}$ where $S_s$ is the scale of crustal shear strength. We generalize the ITD model for fault systems. We investigate deviations of the ITD tails from the Weibull due to sampling bias, magnitude selection, and non-homogeneous strength parameters. Assuming the Gutenberg - Richter law and independence of $m$ on the magnitude threshold, $M_{L,c},$ we deduce that $\tau_s \propto e^{- \rho_{M} M_{L,c}},$ where $\rho_M \in [1.15, 3.45]$ for seismically active regions. We demonstrate that a microearthquake sequence conforms reasonably well to the Weibull model. The stochastic stick - slip model justifies the Weibull ITD for single faults and homogeneous fault systems, while it suggests mixtures of Weibull distributions for heterogeneous fault systems. Non-universal deviations from Weibull statistics are possible, even for single faults, due to magnitude thresholds and non-uniform parameter values.Comment: 32 pages, 11 figures Version 2; minor correction

Ground deformation and source geometry of the 30 October 2016 Mw 6.5 Norcia earthquake (Central Italy) investigated through seismological data, DInSAR measurements, and numerical modelling

We investigate the Mw 6.5 Norcia (Central Italy) earthquake by exploiting seismological data, DInSAR measurements, and a numerical modelling approach. In particular, we first retrieve the vertical component (uplift and subsidence) of the displacements affecting the hangingwall and the footwall blocks of the seismogenic faults identified, at depth, through the hypocenters distribution analysis. To do this, we combine the DInSAR measurements obtained from coseismic SAR data pairs collected by the ALOS-2 sensor from ascending and descending orbits. The achieved vertical deformation map displays three main deformation patterns: (i) a major subsidence that reaches the maximum value of about 98 cm near the epicentral zones nearby the town of Norcia; (ii) two smaller uplift lobes that affect both the hangingwall (reaching maximum values of about 14 cm) and the footwall blocks (reaching maximum values of about 10 cm). Starting from this evidence, we compute the rock volumes affected by uplift and subsidence phenomena, highlighting that those involved by the retrieved subsidence are characterized by significantly higher deformation values than those affected by uplift (about 14 times). In order to provide a possible interpretation of this volumetric asymmetry, we extend our analysis by applying a 2D numerical modelling approach based on the finite element method, implemented in a structural-mechanic framework, and exploiting the available geological and seismological data, and the ground deformation measurements retrieved from the multi-orbit ALOS-2 DInSAR analysis. In this case, we consider two different scenarios: the first one based on a single SW-dipping fault, the latter on a main SW-dipping fault and an antithetic zone. In this context, the model characterized by the occurrence of an antithetic zone presents the retrieved best fit coseismic surface deformation pattern. This result allows us to interpret the subsidence and uplift phenomena caused by the Mw 6.5 Norcia earthquake as the result of the gravitational sliding of the hangingwall along the main fault plane and the frictional force acting in the opposite direction, consistently with the double couple fault plane mechanism

Heritage and Resilience: Issues and Opportunities for Reducing Disaster Risks

This paper examines the unique role of cultural heritage in disaster risk reduction. Itintroduces various approaches to protect heritage from irreplaceable loss and considers ways to draw upon heritage as an asset in building the resilience of communities and nations to disasters. The paper proposes ways forward and builds on the current momentum provided by the Hyogo Framework for Action 2005-2015: Building the Resilience of Nations and Communities to Disasters” (HFA) and the advancement of a post-2015 framework for disaster risk reduction (HFA2) and the post-2015 development agenda. Cultural heritage is often associated with grandiose monuments and iconic archaeological sites that can hold us in awe of their beauty, history and sheer scale. However, the understanding of cultural heritage has undergone a marked shift during the last few decades in terms of what it is, why it is important, why it is at risk and what can be done to protect it. Cultural heritage today encompasses a broader array of places such as historic cities, living cultural landscapes, gardens or sacred forests and mountains, technological or industrial achievements in the recent past and even sites associated with painful memories and war. Collections of movable and immoveable items within sites, museums, historic properties and archives have also increased significantly in scope, testifying not only to the lifestyles of royalty and the achievements of great artists, but also to the everyday lives of ordinary people. At the same time intangibles such as knowledge, beliefs and value systems are fundamental aspects of heritage that have a powerful influence on people’s daily choices and behaviors. Heritage is at risk due to disasters, conflict, climate change and a host of other factors.At the same time, cultural heritage is increasingly recognized as a driver of resilience that can support efforts to reduce disaster risks more broadly. Recent years have seen greater emphasis and commitment to protecting heritage and leveraging it for resilience;but initiatives, such as the few examples that are presented here, need to be encouraged and brought more fully into the mainstream of both disaster risk reduction and heritage management. These are issues that can be productively addressed in a post-2015 framework for disaster risk reduction and, likewise, in the post-2015 development agenda

empathi: An ontology for Emergency Managing and Planning about Hazard Crisis

In the domain of emergency management during hazard crises, having sufficient situational awareness information is critical. It requires capturing and integrating information from sources such as satellite images, local sensors and social media content generated by local people. A bold obstacle to capturing, representing and integrating such heterogeneous and diverse information is lack of a proper ontology which properly conceptualizes this domain, aggregates and unifies datasets. Thus, in this paper, we introduce empathi ontology which conceptualizes the core concepts concerning with the domain of emergency managing and planning of hazard crises. Although empathi has a coarse-grained view, it considers the necessary concepts and relations being essential in this domain. This ontology is available at https://w3id.org/empathi/

GIS procedure to evaluate the relationship between the period of construction and the outcomes of compliance with building safety standards. The case of the earthquake in L’Aquila (2009)

The earthquake (Ml=5.8; Mw=6.3) that shook L’Aquila (Abruzzo region, Italy) on 6 April 2009 and caused huge widespread damage in the other 56 municipalities of the seismic crater has also provided important input to reflect proactively on the need to avoid the repetition of similar tragedies, learning from the calamities that have occurred. In fact, L’Aquila and the other municipalities hit by the earthquake represent an open-air analysis laboratory to reveal and directly see the weak points of the different buildings on the field which did not adequately resist the shocks. In order to provide important data for social utility, in this paper we illustrate the steps which constitute a GIS procedure that we have thought in order to evaluate the relationship between the period of construction and the outcomes of compliance with building safety standards. Through sequential activities which have enabled us to also produce three-dimensional scenarios – of immediate communicative impact and able to show details for interdisciplinary analysis and strategical planning – we have portrayed the urban evolution of L’Aquila per period of construction and mapped the level of damage to the buildings. The relational analysis and quantitative data have permitted us to show that in the case of L’Aquila the major percentages of “unusable buildings”, and also these together with “condemned buildings due to external risks” concern the structures erected until 1955 and then in the 1956- 1975 period, followed by the ones constructed in the periods of 1976-1988 and 1989-1994. Similar results, in conjunction with other specific information, can offer the possibility to define and apply the consolidation measures necessary to tackle future earthquakes in an appropriate way, without a passive sense of resignation and with a deeper awareness of seismic risk