Central Italy Earthquake Research Articles

Earthquake-Induced Spring Discharge Modifications: The Pescara di Arquata Spring Reaction to the August–October 2016 Central Italy Earthquakes

Co-seismic changes in groundwater regime are often observed after moderate to strong earthquakes. The 24 August 2016 Mw 6.0 extensional Amatrice earthquake, which was the first event of a long-lasting seismic sequence, including the 30 October 2016 Mw 6.5 Norcia event, triggered a significant discharge alteration to the Pescara di Arquata spring, located in the Umbria-Marche Apennines (Northern Apennines, Central Italy) and exploited for drinking purposes. During the first five months after the first mainshock, an extra flow of about 30% was recorded, while both water chemistry and temperature did not show significant changes. Thereafter, the spring discharge decreased significantly, and at the end of 2019 it was still lower than normal. The Standardized Precipitation Index (SPI) indicates that these low mean monthly discharge values are not related to particularly dry conditions. The increase in post-seismic depletion coefficients indicates that the aquifer empties faster than it did during the inter-seismic period. The observed transient increase and subsequent decrease of discharge are consistent with a transient, earthquake-related increase in hydraulic conductivity.

Offset components and fault-block motion during the 2016 central Italy earthquake (Mw 6.6, Monte Vettore fault system)

We performed structural analyses on exhumed fault planes in carbonate rock of the Monte Vettore fault system (Central Italian Apennines). Slip on these faults was responsible in 2016 for a Mw 6.6 earthquake, accompanied by 30-km-long surface rupture. We focused on scratches, a peculiar coseismic abrasion feature that is rarely described and analysed in structural geology, mainly because of its ephemeral nature (most of scratches disappear after just a few months). We surveyed coseismic scratches and slip vectors of coseismic surface ruptures that, coupled with conventional striae analysis, provide interesting clues to the kinematic behavior of the hanging-wall during the 2016 mainshock. First, we investigated whether or not scratches could be considered as kinematic indicators and if they could really add information to results of striae analysis. To this end, we compared the statistical analysis of scratches with those obtained from conventional fault-surface structural elements or inferred from other geological, seismological and geodetical data. Results show that the movement of the hanging-wall of the Monte Vettore fault system during the October 30, 2016, mainshock can be traced back to two components. The first, major component is kinematically linked to deep tectonic deformation. The second, minor component, is related to passive-slip deformation induced by the complexity of reciprocal motion between hanging-wall and footwall.

Model Updating of Historical Belfries Based on Oma Identification Techniques

ABSTRACT Central Italy Earthquakes occurred in 2016 pointed out once more the vulnerability of Cultural Heritage (CH), especially for what concerns bell-towers since they tend to get dramatically damaged due to their considerable slenderness and deterioration, endangering their surroundings and making their preservation fundamental. This work presents the results of the study carried out on four different isolated masonry bell towers, located in Ferrara province (Italy); the parameters of the materials were deduced by calibrating Finite Element Models (FEMs) using the data collected during an investigation campaign conducted with a wired accelerometric sensor system, since it was not possible to apply destructive methodologies. Dynamic data were extracted through the application of two Operational Modal Analysis (OMA) identification techniques: the Enhanced Frequency Domain Decomposition (EFDD) and the Stochastic Subspace Identification (SSI) methodology. Particular attention was devoted to the use of MAC matrix in the validation of the mode shapes results.

Sequential modelling of the 2016 Central Italy earthquake cluster using multisource satellite observations and quantitative assessment of Coulomb stress change

SUMMARYA sequence of earthquake events consisting of three large shocks occurred in Central Italy from August to October in 2016 with the duration of almost 2 months. The preliminary study on the seismic mechanism suggests that the sequence of events is the result from the activity of the SW dipping Mt Bove–Mt Vettore–Mt Gorzano normal fault system. For investigation and understanding of the coseismic faulting of the seismogenic fault alignment, we collect a set of comprehensive satellite observations including the Sentinel-1A, ALOS-2/PALSAR-2 and GPS data to map the coseismic surface deformation and estimate the source models in this study. The derived faulting model for the first Amatrice event is characterized by two distinct slip asperities suggesting that it is a predominantly normal dip-slip motion with slight strike-slip component. The second event, Visso earthquake is almost a purely normal rupture. The third Norcia event is dominated by the normal dip-slip rupture of the seismogenic fault, and has propagated up to the ground with significant slip. The three faulting models are then utilized to quantify the Coulomb failure stress (CFS) change over the seismic zone. First, the CFS change on the subsequent two seismogenic faults of the earthquake sequence is estimated, and the derived positive CFS change induced by the preceding earthquakes suggests that the early events have positive effects on triggering the subsequent seismicity. We then explore the response relation of the aftershocks including 961 events with magnitudes larger than M 3.0 to the CFS change over the seismic zone. It suggests that the rupture pattern of the aftershocks is similar to the major shocks with predominantly normal dip-slip. To assess the risk of the future seismic hazard, we analyse quantitatively the spatial distribution of aftershock occurrence and CFS transfer at the seismogenic depth, indicating that the ruptures of the three major shocks do partly release the accumulated strain on the associated fault alignment as well as the dense aftershock, but the CFS increase zone with few aftershocks in the southwest of the eastern Quaternary fault alignment of Central Italy poses the potential of further rupture. In particular, the distribution of aftershock migration also suggests that the north extension of the Mt Bove fault is the potential zone with rupture risk.

Interactions of Earthquakes in Central Italy over the Past 100 Yr through Coulomb Stress Changes, and Implications for Seismic Hazards

ABSTRACT Italy has a historical earthquake record that is complete for events with a magnitude above 5.8 since A.D. 1349, making it possible to study Coulomb failure stress changes (ΔCFS) over a long period. In this study, we investigated the interactions between moderate-to-large earthquakes through ΔCFS over 100 yr in central Italy. This region is characterized by intense seismicity with predominantly extensional components. Hence, earthquake hazard assessment is of great public concern. Besides, earthquake interactions on normal faults are relatively less studied compared to reverse and strike-slip faults. ΔCFS calculations in this study incorporated both coseismic stress transfer and postseismic viscoelastic relaxation, and found the epicenters of 13 out of 15 events located in positively stressed lobes induced by previous earthquakes, confirming a correlation between the ΔCFS pattern and locations of moderate-to-large earthquakes. Next, we estimated the current distribution of ΔCFS on active faults, and after a comprehensive analysis of ΔCFS accumulation, slip rates, historical seismicity, and locations of populated cities, we identified three regions of potential seismic hazards in this region.

The Pilato Lake (Sibillini Mts., Central Italy): first results of a study on the supposed variations of its hydrogeological conditions induced by the seismic sequence 2016-2017

The Pilato Lake has glacial origin, is located in the Sibillini Mountains, Central Italy, and is characterized by the endemism of the small crustaceous Chirocephalus marchesonii. In the context of a research agreement with the Monti Sibillini National Park, the ISPRA Geological Survey of Italy is carrying on some studies aimed to evaluate the supposed effects of the 2016–2017 Central Italy earthquakes on the hydrogeological conditions controlling the lake’s evolution. The study, started in July 2018, aims primarily at the reconstruction of the geological and hydrogeological subsoil setting, beneath the valley hosting the lake. In order to define the conceptual model of groundwater circulation and, thus, to evaluate the emptying and recharge seasonal cycle of the lake, hydrogeological surveys and geophysical investigations were performed. The research program is still in progress and only preliminary results may be proposed. The hydrogeological surveys demonstrate the absence of geomorphological evidence of seismic-induced surface fractures generated by the seismic sequence 2016-2017. Consequently, the complete drying of the lake, occurred in summer 2017, was probably due to meteoclimatic reasons and/ or to not yet verified variations in the permeability characteristics of the surficial deposits and/or bedrock affecting the infiltration towards the subsoil, caused by the severe seismic shaking. The low electrical conductivity values of the lake’s waters are in accordance with the prevailing origin of the lake’s recharge by snow melting and direct rainfall. As concerns the first geophysical surveys in the Pilato Lake area, seismic surveys by surface wave method assessed that the maximum thickness of debris here estimated is about 12.5-14 m. As a whole, the factors responsible for the progressive lowering of the lake level are: i) the water overflow through the Fonte del Lago spring, ii) the evaporation from the lake surface and iii) the drainage through the scarcely permeable glacial deposits towards the Basal Calcareous Aquifer, hosted within the limestone at lower altitude.

Heritage waste management

PurposeThe considerable volume of rubble generated by the 2016–2017 earthquakes in central Italy reveals a significant issue in the post-disaster reconstruction phase. Drawing from the experience of Macerata province and the city of Camerino, the purpose of this paper is to explore a possible change of attitude in the reuse of heritage waste materials in the reconstruction process of damaged historical villages and towns in Italy.Design/methodology/approachThis research outlines a comparison between national and regional directives on the rubble management on the one hand, and the praxis on the other, carrying out semi-structured interviews with experts who have been involved in the reconstruction process of Macerata province and Camerino, in Marche region.FindingsThe research reveals that the current vision in Italy for the management of disaster waste is still very close to the traditional paradigm that gives heritage waste an intrinsic value, worthy of great efforts for its collection, catalogue and preservation in view of the likely philological restoration of the damaged heritage. The most recent experiences in Camerino show that institutions responsible for the conservation of cultural heritage may accept a possible paradigm shift towards a more innovative and less expert-driven approach to heritage waste materials and their possible upcycling.Originality/valueWithin a critique of the traditional restoration paradigm, this article links disaster waste management to the Sendai Framework for Disaster Risk Reduction, to enhance the long-term sustainability of historical villages and towns in Italy.

Nonlinear modeling of unreinforced masonry structures under seismic actions: validation using a building hit by the 2016 Central Italy earthquake

The authors wish to express their gratitude to the Seismic Observatory of Structures, RELUIS and Ing. Serena Cattari of the University of Genova for the material provided for the development of the present work. The work was carried out thanks to the financial support of the European Commission within the framework of the SAHC master course. The authors are grateful to the SAHC Consortium and the University of Minho in Guimaraes (Portugal) for the support provided.

A Reappraisal of the 1968 Valle Del Belice Seismic Sequence (Western Sicily): A case study of Intensity Assessment with Cumulated Damage Effects

In 1968, six earthquakes with magnitude between 5.1 and 6.4 destroyed or heavily damaged several towns in the Valle del Belice (western Sicily), causing some three hundred fatalities. There have been some critical issues in the intensity assessment however in the macroseismic studies produced over the years , since the MCS scale was used as an estimation of shaking rather than a representation of the damage scenario; in practise, intensity was assigned for each earthquake of the sequence disregarding the effect of the cumulative damage. The case-study of the 2016-17 earthquakes in Central Italy reflected the difficulty in estimating the intensity in localities repeatedly hit by strong shocks, producing macroseismic parameters (epicentre, magnitude) inconsistent with the instrumental ones. As for the 1968 Valle del Belice sequence, the Parametric Catalogue of Italian Earthquakes CPTI15 reports the macroseismic parameters, owing to the inadequacy of the seismic network operating in Italy in that period. Aware of the issues related to epicentre locations and magnitudes calculated by the existing macroseismic datasets, here we propose a reappraisal of the 1968 earthquakes following a methodology tested during the 2016-17 seismic sequence in Central Italy. By a new analysis of the primary sources, we reconstruct the evolution of the damage scenario during the sequence and assess intensity by using the European Macroseismic Scale EMS-98; the new macroseismic parameters are finally compared with the ones of the CPTI15 catalogue. Lastly, we propose a procedure for minimizing the magnitude overestimation in case of seismic sequences, based on the computation of the total seismic moment M 0 .

The role of reinforced concrete roofs in the seismic performance of masonry buildings

The 2016 Central Italy earthquake caused many collapses of existing masonry buildings that had previously been retrofitted with reinforced concrete roofs. The aim of this paper is to explore the role of these roofs in the seismic behaviour of masonry buildings. Simple analytical models are presented to illustrate two typical out-of-plane collapse mechanisms: wall overturning and vertical flexure. The models are based on linear kinematic analysis, which allows fast modelling and calculation of a coefficient that can be used to assess the safety level of a structure. Nonlinear kinematic analyses were also performed. Both methods were applied to two case studies taken from areas struck by the earthquake. Results show that linear analysis represents an effective tool for preliminary verifications that can allow one to understand whether retrofit interventions are needed.

A Study on the Cooperative Relationship between Main Actors on the Recovery Period of 2016 Central Italy Earthquake

A Study on the Cooperative Relationship between Main Actors on the Recovery Period of 2016 Central Italy Earthquake

Mapping the geology of the 2016 Central Italy earthquake fault (Mt. Vettore – Mt. Bove fault, Sibillini Mts.): geological details on the Cupi – Ussita and Mt. Bove – Mt. Porche segments and overall pattern of coseismic surface faulting

We present the results of a field survey performed in the centralnorthern portion of the Mt. Vettore – Mt. Bove normal fault(VBF), reactivated during the 2016 central Italy earthquake sequence (24 August, Mw 6.0; 26 October Mw5.4 and Mw 5.9; 30 October Mw 6.5). The field survey was carried out by means of digital mapping techniques, and traditional methods on 1:10,000-scale topographic maps. The field work had two main aims: 1) to detail the geology of the central-northern VBF, and to constrain the segmentation and displacement distribution of the entire VBF system; and 2) to map in detail the ruptures of the 26 and 30 October events, filling in the gaps left by previous studies, and provide constraints on the coseismic parameters of the 2016 earthquakes.The results are summarized in a composite geological map, organized in 8 frames showing: the structural architecture in map view of the VBF system (frames 1 and 2); 1:25,000-scale geological maps of the Cupi-Ussita (frame 3) and Mt. Bove – Mt. Porche (frame 4) sectors of the VBF; twelve 1:25,000-scale geological sections for computing the geological displacements (frame 5); a summary of the coseismic parameters of the 2016 earthquakes (diagrams of net displacement, throw and opening; Surface Rupture Length, SRL; Maximum Displacement, MD and Average Displacement, AD) (frame 6); a comparison of the 2016 coseismic parameters with normal faulting earthquakes occurred globally (frame 7); and a computation of the morphological displacement (post-Last Glacial Maximum, LGM) across the VBF, a comparison among geological, morphological and coseismic displacements, and a quantification of the tectonic back-tilting in the area of maximum coseismic displacement (frame 8). Some implications are discussed in this accompanying note, such as the role of fault segmentation deduced from structural geology and tectonic geomorphology in controlling the coseismic displacement, the role of back-tilting in amplifying the coseismic displacement and the limits of empirical regressionsin predicting the relations between rupture parameters and Mw in case of segmented normal faults.

Post-earthquake reconstruction as an opportunity for a sustainable reorganisation of transport and urban structure

The reconstruction of a damaged historic/modern urban system following a natural catastrophic event, even if sophisticated, complex and expensive can become an opportunity to apply innovative methods of urban regeneration oriented towards environmental sustainability. A research by the University of L'Aquila exploring the consequences of the 2009 earthquake in central Italy, both in analytical and design terms, is focused on this theme, applying innovative principles to the reconstruction project of the city of L'Aquila, capital of the Abruzzo Region (Italy). The study carries out an analysis of the earthquake effects on urban systems and mobility and proposes an operating strategy based on a multidisciplinary approach that integrates urban design and sustainable mobility strategies. In particular, it outlines the components of Strategic Projects that has been developed for the reconnection of the urban fragments created by the dispersion of the city after the earthquake, which has applied the principles of multi-modal sustainable mobility.The results of the study show that the post-quake reconstruction, if properly interpreted, can be a unique opportunity to conceive and construct the conditions to implement a new and more efficient urban sustainable transport model through advanced technologies based on outlining an innovative urban redesign approach.

Real-time coseismic deformations from adaptively tight integration of high-rate GNSS and strong motion records

SUMMARYIn traditional tight integration of high-rate GNSS and strong motion sensors, an appropriate process variance is crucial for obtaining accurate broad-band coseismic deformations. In this paper, instead of using a subjectively empirical value, we present an approach for determining the process variance adaptively based on the adaptive Kalman filter for real-time use. The performance of the approach was validated by the colocated stations collected during the 2010 Mw 7.2 earthquake in El-Mayor, 2016 Mw 7.8 earthquake in New Zealand and 2016 Mw 6.5 earthquake in central Italy. The results show that this method complements the advantages of GNSS and strong motion accelerometers and can provide more accurate coseismic waveforms especially during the strong shaking period, due to the ability of the method to adjust the process variance in real time according to the actual status of the station. In addition, this method is also free from the influence of the baseline shift. Testing of the new method for the integration of strong motion and multi-GNSS indicates that multi-GNSS has an obvious improvement in the precision while single GPS has a poor observation condition.

Guest editorial: the 2016 central Italy earthquakes

Guest editorial: the 2016 central Italy earthquakes

Visual analytics of aftershock point cloud data in complex fault systems

Abstract. Aftershock point cloud data provide direct evidence for the characteristics of underground faults. However, there has been a dearth of studies using state-of-the-art visual analytics methods to explore the data. In this paper, we present a novel interactive visual analysis approach for visualizing the aftershock point cloud. Our method employs a variety of interactive operations, rapid visual computing functions, flexible display modes, and various filtering approaches to present and explore the desired information for the fault geometry and aftershock dynamics. The case study conducted for the 2016 Central Italy earthquake sequence shows that the proposed approach can facilitate the discovery of the geometry of the four main fault segments and three secondary fault segments. It can also clearly reveal the spatiotemporal evolution of the aftershocks, helping to find the fluid-driven mechanism of this sequence. An open-source prototype system based on the approach is also developed and is freely available.

PHOTOGRAMMETRY AS A PARTICIPATORY RECOVERY TOOL AFTER DISASTERS: A GROUNDED FRAMEWORK FOR FUTURE GUIDELINES

Abstract. This paper identifies the application domain, context of use, processes and goals of low-cost street-level photogrammetry after urban disasters. The proposal seeks a synergy between top-down and bottom-up initiatives carried out by different actors during the humanitarian response phase in data scarce contexts. By focusing on the self-organisation capacities of local people, this paper suggests using collaborative photogrammetry to empower communities hit by disasters and foster their active participation in recovery and reconstruction planning. It shows that this task may prove technically challenging depending on the specifics of the collected imagery and develops a grounded framework to produce user-centred image acquisition guidelines and fit-for-purpose photogrammetric reconstruction workflows, useful in future post-disaster scenarios. To this end, it presents an in-depth analysis of a collaborative photographic mapping initiative undergone by a group of citizen-scientists after the 2016 Central Italy earthquake, followed by the explorative processing of some sample datasets. Specifically, the paper firstly presents a visual ethnographic study of the photographic material uploaded by participants from September 2016 to November 2018 in the two Italian municipalities of Arquata del Tronto and Norcia. Secondly, it illustrates from a technical point of view issues concerning the processing of crowdsourced data (e.g. image filtering, selection, quality, semantic content and 3D model scaling) and discusses the viability of using it to enrich the pool of geo-information available to stakeholders and decision-makers. Final considerations are discussed as part of a grounded framework for future guidelines tailored to multiple goals and data processing scenarios.

2016 Central Italy Earthquakes: comparison between GPS signals and low-cost distributed MEMS arrays

Abstract. Modern seismic ground-motion sensors have reached an excellent performance quality in terms of dynamic range and bandwidth resolution. The weakest point in the recording of seismic events remains spatial sampling and spatial resolution, due to the limited number of installed sensors. A significant improvement in spatial resolution can be achieved by the use of non-conventional motion sensors, such as low-cost distributed sensors arrays or positioning systems, capable of increasing the density of classical seismic recording networks. In this perspective, we adopted micro-electro mechanical system (MEMS) sensors to integrate the use of standard accelerometers for moderate-to-strong seismic events. In addition, we analyse high-rate distributed positioning system data that also record soil motion. In this paper, we present data from the 2016 Central Italy earthquakes as recorded by a spatially dense prototype MEMS array installed in the proximity of the epicentral area, and we compare the results to the signal of local 1s GPS stations. We discuss advantages and limitations of this joint approach, reaching the conclusion that such low-cost sensors and the use of high rate GPS signal could be an effective choice for integrate the spatial density of stations providing strong-motion parameters.

Understanding the interacting factors that influence social vulnerability: a case study of the 2016 central Italy earthquake.

This paper seeks to identify those areas that proved socially vulnerable to the earthquake that struck central Italy on 24 August 2016. The study involved four key steps. First, six relevant social vulnerability indicators were selected, based on previous conclusions in the literature. Second, the indicators were mapped using the inverse distance weighted interpolation method. Third, social vulnerability was assessed according to a spatial combination of the indicators. Fourth, in order to build a heterogeneity map, another approach was employed to represent the spatial variability of social vulnerability and to provide additional information on the synergistic contributions of the indicators. The results indicate that age and accessibility indicators affect the entire region under review, with highly vulnerable zones being close to small historical centres. These findings will be useful to governments, policymakers, and stakeholders with regard to implementing vulnerability mitigation strategies in Italian territories that are highly susceptible to earthquake hazards.

Tracking Modal Parameter Evolution of Different Cultural Heritage Structure Damaged by Central Italy Earthquake of 2016

The preliminary results of an ambient-vibration based investigation conducted on a large sample of historic masonry towers in the Marche region (Central Italy) are presented, with a focus on the belfry of Collegiata of Santa Maria in Visso (Italy). The assessment procedure includes full-scale ambient vibration testing, modal identification from ambient vibration responses, finite element modeling and dynamic-based identification of the uncertain structural parameters of the model. As the most doubtful parameters, the modulus of elasticity of the masonry is adjusted to achieve the experimental results with numerical model by simple operations.