1,721,002 research outputs found
Assessment of attenuation regressions for earthquake-triggered landslides in the Italian Apennines: insights from recent and historical events
No full textWe address the modeling of spatial distribution of coseismic landslides, based on an empirical approach applied to both recent and historical well-documented events. We analyze a dataset of 11 historical and recent normal faulting earthquakes in the Italian Central Apennines. Firstly, making use of a kernel density estimator approach, we calculated the regression between the extent of the maximum area affected by landslides (A; km2) and Mw, on the combined dataset of recent and historic earthquakes: Log A = (1.0397 Mw)–3.9288. Then, for recent earthquakes only, we analyzed the attenuation regression of landslide density (Dens; no. of landslides/km2) with distance from surface fault trace (Dfault; meters): Dens = 0.3661 × exp (− 5.053 Dfault). Historical events, still presenting systematically lower values of landslide densities, can be regressed on the same functional form resulting in a similar factor of attenuation with distance but with a different scaling factor. We thus argue that empirical regressions on historical earthquake-triggered landslides can be successfully exported elsewhere if a well-documented catalog is present and a calibration with several recent events can be done
Analisi e modellazione dei fattori geologico-ambientali nella localizzazione dei siti industriali: il caso del bacino padano.
Full text linkIl progetto di ricerca sviluppato nel corso del Dottorato ha l’obiettivo di illustrare come una rigorosa analisi geologica consenta di identificare, valutare e mitigare gli effetti di eventi naturali estremi, che possono costituire un serio fattore di rischio per gli impianti industriali e le aree metropolitane; a tale scopo, sono state selezionate due aree campione localizzate all’interno del bacino Padano, dove si sono condotte analisi geositologiche ed ambientali per caratterizzare le interazioni tra contesto naturale e impianto industriale: una discarica di rifiuti non pericolosi nel Comune di Cairo Montenotte (Sv) e l’area urbana di Como.
Nel caso di Cairo Montenotte, sono state condotte indagini geognostiche e geofisiche, prove in sito e di laboratorio e monitoraggio strumentale; altre indagini sperimentali sono state mirate alla caratterizzazione delle proprietà fisiche e meccaniche dei rifiuti, con particolare riferimento alla stabilità e all’evoluzione dei cedimenti del cumulo dei rifiuti.
La città di Como sorge su sedimenti di origine palustre molto recenti e soggetti a subsidenza; l’analisi di oltre 300 stratigrafie di sondaggio e delle prove geotecniche disponibili ha consentito di ricostruire l’assetto stratigrafico del sottosuolo mediante profili geologico-tecnici; il continuo monitoraggio della rete piezometrica comunale e dei parametri idrologici del bacino lacustre ha permesso di caratterizzare la circolazione idrica sotterranea. Sono stati poi approfonditi alcuni aspetti relativi alla presenza di lineamenti strutturali di importanza regionale, in particolare il Retroscorrimento di Monte Olimpino e infine sono state condotte alcune elaborazioni per ricostruire l’evoluzione paleo-ambientale dell’area a partire dalla deglaciazione.
The main goal of the project is to illustrate how the rigorous geological analysis allows to identify, assess, and mitigate extreme geological hazards, which might be a serious factor of environmental risk for the local industrial plants and large metropolitan areas. We selected 2 study areas in the Po Plain, a non-hazardous waste landfill located in Cairo Montenotte (Savona province), and the Como urban area. At these sites we perform several analysis in order to characterize the interactions between natural environment and industrial plants or critical facilities.
In the Cairo Montenotte case, core drillings, geophysical analysis and laboratory tests were conducted; moreover, the physical and mechanical properties of the waste were analyzed, specifically concerning waste stability and landfill subsidence. The mutual impacts between the industrial waste treatment plant and the natural environment have been analyzed and assessed.
The Como urban area lies on very recent palustrine sediments, an environment showing remarkable Holocene subsidence, and high potential for liquefaction and coastal flooding; the stratigraphic setting was reconstructed analyzing more than 300 borehole logs and geotechnical tests, and building new geological sections; wells monitoring allowed to characterize groundwater circulation. Some aspects related to the structural setting (e.g., Monte Olimpino Backthrust) and the Late Quaternary environmental evolution were also closely examined. The results of this comprehensive geological analysis have been used in order to assess the environmental impact of the new integrated defense system against floods, presently under construction along the Como lakeshore. This critical facility consists of rows of mobile gates which are intended to hydrologically isolate the town during events of very high level of the Lake Como.
In both cases it is possible to show how a proper approach for the geological siting is a critical tool for A) ensuring the environmental safety of the local industrial plant or critical facility, and B) reducing the operational costs by preventing from repeated readjustment of the project due to poorly defined design parameters
Prediction of coseismic rupture locations from fault maps
No full textCoseismic fault displacement is a localized source of hazard following surface-rupturing earthquakes. Here, we exploit the usefulness of geological maps and fault traces contained therein, to predict the location of coseismic ruptures (CORs). We analyze five earthquakes that occurred inItaly and the UnitedStates, measuring (1) the amount of CORs that occurred along previously mapped faults and (2) the amount of already mapped faults that actually moved during a strong earthquake. These quantities are 32% ± 30% and 20% ± 11%. The values are highly variable depending on the investigated earthquake and are influenced by the distance from the principal fault, the structural ranking, and the quality of geological maps. Ruptures structurally connected and close to the principal fault are more easily mapped. Weinvestigate whether geological maps could be exploited in the context of hazard assessment, and we suggest that specific regressions which consider available fault maps could be applied to compute the probability of occurrence of distributed faulting. Moreover, we perform a preliminary binomial logistic classification to identify a distance threshold from the principal fault to infer possible fault reactivation. A reliable geological map is a useful tool for hazard and fault capability assessment, land planning and resource management, and prompting for the need for proper resource allocation. Some critical aspects that need to be addressed in the future include how to properly include geological knowledge and how to treat triggered ruptures in modeling approaches
Exploiting earthquake-induced landslide inventories for macroseismic assessment using the environmental seismic intensity (ESI-07) scale
Full text linkEarthquake-induced landslides are one of the most impacting effects triggered by seismic events and represent a relevant risk factor. Inventories of earthquake-induced landslides are available for many case histories and may contain thousands of elements. The spatial pattern of landslides is typically analyzed in terms of density and areal coverage (LND: Landslide Number Density; LAP: Landslide Area Percentage). In addition to landslides, other earthquake environmental effects, such as surface faulting, liquefaction, or tsunami, may be triggered. A comprehensive evaluation of earthquake environmental damage can be achieved using the Environmental Seismic Intensity (ESI-07) scale; however, landslide inventories have not yet been fully exploited in terms of ESI-07 assessment. Here, we apply a grid-based methodology to compute LND, LAP and ESI-07 values for 40 landslide inventories related to 33 earthquakes worldwide. We derive the first empirical equations relating ESI-07 to LND or LAP, demonstrating that the LAP metric is more robust. We also find that the inventory itself (i.e., how landslide polygons are delineated) introduces much higher uncertainty into the process compared to the selection of a specific area-volume conversion equation. A comparison with independent ESI-07 data shows that the proposed procedure is reliable. We claim that our approach can be applied in other contexts and could represent the basis for enhanced collaboration between the scientific communities working on landslides and seismic intensity assessment
Developing the First Intensity Prediction Equation Based on the Environmental Scale Intensity: A Case Study from Strong Normal-Faulting Earthquakes in the Italian Apennines
Full text linkEarthquakes produce effects on the built and natural environment, the severity of which decays with distance from the epicenter. Empirical relations describing the intensity attenuation with distance are fundamental for seismic hazard assessment and for deriving parameters for preinstrumental events. Seismic intensity is usually assigned based on damage to buildings and infrastructures; this can be challenging for intensity degrees higher than X or when macroseismic fields of multiple events close in time are overlapping. A complementary approach is the study of earthquake environmental effects (EEEs), which are used to assign intensity on the environmental scale intensity (ESI) scale. However, a quantitative comparison between the ESI and traditional scales, and an equation describing the ESI attenuation with distance are still lacking. Here, we analyze 14 historical and instrumental events (time window 1688–2016) in the central and southern Apennines (Italy), comparing ESI and Mercalli–Cancani–Sieberg (MCS) intensities. Our results show that ESI consistently provides higher intensity near the epicenter and the attenuation is steeper than MCS. We derive the first intensity prediction equation for the ESI scale, which computes local intensity as a function of distance and epicentral intensity value. We document that, in the near field, the MCS attenuation for shallow crustal events occurred in the twenty‐first century is steeper than previous events, whereas the ESI attenuation shows a consistent behavior through time. This result questions the reliability of current empirical relations for the investigation of future events. We recommend including EEEs in intensity assignments because they can guarantee consistency through time and help in evaluating the spatial and temporal evolution of damage progression during seismic sequences, thus ultimately improving seismic risk assessment
Archaeoseismology and paleoseismology in the area of Tiberias city, Sea of Galilee - preliminary results.
No full textThe city of Tiberias (Israel) is sited on the shores of the Sea of Galilee, a pull-apart basin located along the Dead Sea Transform. This paper aims to present the first results of a cross-disciplinary investigation focused on the evaluation of earthquake hazard for the city: aerial photo interpretation and field survey were combined with shallow seismic surveys and paleoseismic analyses. An archaeoseismic survey has been performed on two different archaeological structures, a Roman theatre and the remains of a church. Further work has to be done for a complete seismic hazard characterization, but our study highlights several deformation features that might be earthquake related; specifically, a previously unknown fault trace has been constrained both on natural sediments and archaeological structures
Quaternary geology, paleoseismology and earthquake hazards in regions with moderate active tectonics and high vulnerability: the seismic landscape of the Po Plain.
No full textPrimary surface faulting across the Roman Theatre at Berniki, Sea of Galilee: new archaeoseismic and structural data
No full textThe Dead Sea Transform (DST) is a continental transform representing the boundary between Arabia and Sinai plates
and accommodating a long-term slip rate of about 4-5 mm/a (e.g. Garfunkel et al., 2014). The DST shows the alternation
of millennial periods of quiescence and seismic clusters, i.e., sequence of surface-rupturing earthquakes triggering each
other in a short time laps. Seismic gaps suggest that presently several fault segments, including the Jordan Valley fault,
are locked and strain is accumulating (Hamiel et al., 2016).
We focus our efforts at the N tip of the Jordan Valley, at the Sea of Galilee (SOG) area, which is a subsiding basin
bounded to the E by a left-lateral fault and to the W by the Tiberias normal fault, splaying at surface into several fault
strands. In particular, we investigate the seismicity and paleoseismicity of the 8th century AD, when strong shocks
clustered in time and space along this sector of the DST. Our investigation includes (Ferrario et al., 2015): i) re-interpretation of historical chronicles and available data; ii)
analysis of a 0.5-m-resolution airborne Lidar of the entire SOG shores; iii) high-resolution seismic reflection profiles; iv)
archaeoseismic and mesostructural surveys at two Roman sites in Tiberias, Berniki Theatre and the Southern City Gate
(v) paleoseismological analysis.
Preliminary results clearly map the strand of an active fault crossing the theatre, where a 60-cm vertical offset has
been measured and dated by means of archaeological stratigraphy. A terrestrial Lidar survey, which is now in progress,
will allow to measure with cm-accuracy the vertical and lateral components of coseismic displacement. We interpret the
damage as primary surface faulting of one of the 8th century mainshocks. This interpretation is shading light on the “749
AD event” and contributing to the identification of the main faults which were activated during this event
Trasformazioni ambientali e interazione uomo-ambiente nella zona di interfaccia fra lago e area emersa a Como: sintesi delle conoscenze e nuove prospettive per la ultimi 5000 anni
Full text linkThe Como urban area represents a particularly suitable site for the analysis of the recent
environmental evolution and for the understanding of the interactions between natural processes and
human impact on the landscape. Archaeological and geological data collected in the last 15 years
highlight the evolution of the local river network and of the coastal area since ca. 5000 yr B.P
Fifteen years of Environmental Seismic Intensity (ESI-07) scale: Dataset compilation and insights from empirical regressions
No full textThe Environmental Seismic Intensity scale (ESI-07), published 15 years ago under the umbrella of INQUA (International Union for Quaternary Research), is solely based on earthquake effects on the natural environment. ESI-07 provides complementary information with respect to other macroseismic scales, in particular those stemming from the original Mercalli scale, which are mainly based on effects on manmade structures. We collect information on 157 earthquakes, occurred between 300 AD and 2020, that have been studied using the ESI-07 scale. The ESI-07 epicentral intensity can be assigned based on linear or areal features (e.g., length of surface rupture, area affected by environmental effects); this value is generally in good agreement, or slightly larger, than estimates provided using other macroseismic scales. Higher discrepancies are found for earthquakes with
ESI-07 epicentral intensity above X, where other scales tend to saturate, as expected based on the original definition of the Mercalli-family intensity scales. We develop scaling relations among ESI-07 epicentral intensity and moment magnitude, surface rupture length and affected area. After critically evaluating the scientific literature, we argue that the ESI-07 reached its original goals and proved to be particularly useful for the documentation of earthquake damage i) in remote regions, ii) in the case of strong events, where other scales saturate, and iii) in the region closer to the epicenter. Finally, we identify gaps where to focus future efforts, such as the integration of remote sensed datasets in ESI-07 assignment and the refinement of empirical regressions
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