Analysis of a database of landslides triggered by the 2016 Central Italy seismic sequence  

2021 ◽  
Author(s):  
Giovanni Forte ◽  
Melania De Falco ◽  
Federica Iannicelli ◽  
Antonio Santo
Keyword(s):  
Central Italy ◽  
Google Earth ◽  
Mountain Range ◽  
Seismic Sequence ◽  
Large Area ◽  
Geometrical Characterization ◽  
Seismic Parameters ◽  
Main Shocks ◽  
Ground Effects ◽  
Transportation Routes

<p>The seismic sequence that struck Central Italy in 2016 was characterized by three main shocks respectively occurred on August 24<sup>th</sup> Mw 6.0; October 26<sup>th</sup> Mw5.9 and October 30<sup>th</sup> Mw 6.5. The seismic sequence caused several ground effects over a large area of ​​the central Apennine mountain range, mainly affecting transportation routes.</p><p>In the aftermath of the sequence, several research groups mapped around 820 landslides involving road cuts in rock and fill slopes over an area of about 2000 km<sup>2</sup> (GEER,ISPRA, C.E.R.I. by Roma La Sapienza). These data are summarized in the CEDIT catalog by Martino et al., (2017), where almost 150, 250 and 420 instability phenomena were respectively triggered by each mainshock. Further updates were carried out by the Authors in the framework of the Reluis projects of the Department of Civil Protection. In particular, other 550 phenomena were mapped by interpretation of aero photos provided by google-earth. For some of the largest ones, field surveys were carried out for mechanical, structural, and geometrical characterization.</p><p>The dataset distribution was analyzed with geological, geomorphological, and seismic parameters, such as lithology, fault distance, landslide run-out, estimates of mobilized volumes, distance from the epicenter, PGA, and damages.</p><p>The triggered events are mainly characterized by Category I of Keefer (1984) classification, namely rockfalls and rockslides. The maximum triggering distance resulted as high as 50 km far from the epicenter. The most affected areas are characterized by ridge crests or flanks of valleys in carbonate rocks.</p><p>This study permitted to highlight the most relevant parameters for the assessment of earthquake-triggered susceptibility for the study area and identify some meaningful and critical case studies for the future development of the research.</p><p> </p>

Spatio-temporal variation of Anaelastic and Scattering Seismic Attenuation during the 2016-2017 Central Italy Seismic Sequence

2021 ◽  
Author(s):  
Simona Gabrielli ◽  
Aybige Akinci ◽  
Ferdinando Napolitano ◽  
Luca De Siena ◽  
Edoardo Del Pezzo ◽  
...  
Keyword(s):  
Wave Attenuation ◽  
Central Italy ◽  
Temporal Variations ◽  
Seismic Attenuation ◽  
Coda Wave ◽  
Seismic Sequence ◽  
Rock Fracturing ◽  
Low Frequencies ◽  
Main Shocks ◽  
Stress Changes

<p>Between August and October 2016, the Central Apennines in Italy have been struck by a long-lasting seismic sequence, known as the Amatrice (Mw 6.0) - Visso (Mw 5.9) - Norcia (Mw 6.5) sequence. The cascading ruptures occurred in this sequence have been considered connected to the fluid migration in the fault network, as suggested by previous studies. The behaviour of fluids in the crust is crucial to understand earthquakes occurrence and stress changes since fluids reduce fault stability. It has long been understood that the seismic attenuation is strongly controlled by the structural irregularity and heterogeneities; micro-cracks and cavities, either fluid-filled or dry, temperature and pressure variations cause a decrease in seismic wave amplitude and pulse broadening. Hence seismic attenuation imagining is a powerful tool to be a relevant provenance of information about the influence and abundance of fluids in a seismic sequence.</p><p>The aim of this work is to separate scattering and absorption contributions to the total attenuation of coda waves and to provide their spatial and temporal variations at different frequency bands of these quantities using two datasets: the first one comprising 592 earthquakes occurred before the sequence (March 2013-August 2016) and the second one comprising 763 events (ML > 2.8) from the Amatrice-Visso-Norcia sequence. Scattering and absorption have been measured through peak-delay and coda-wave attenuation parameters (the latter inverted using frequency-dependent sensitivity kernels).</p><p>The preliminary results show a clear difference between the pre-sequence and sequence images, mainly at low frequencies (1.5 Hz), where we can define a spatial increase of scattering with time attributed to rock fracturing and fluid circulation. The coda attenuation tomography also demonstrates a clear variation between the pre-sequence and the sequence over series of time windows being before and after the largest main shocks of the seismic sequence, with an increase of the attenuation in space with decreasing time. The peak delay indicates a high scattering area corresponding to the Gran Sasso massif and L’Aquila zone, where an important seismic sequence (Mw 6.3) occurred in 2009.</p>

Fault Segmentation as Constraint to the Occurrence of the Main Shocks of the 2016 Central Italy Seismic Sequence

Tectonics ◽  
2017 ◽  
Vol 36 (11) ◽  
pp. 2370-2387 ◽  
Author(s):  
A. Pizzi ◽  
A. Di Domenica ◽  
F. Gallovič ◽  
L. Luzi ◽  
R. Puglia
Keyword(s):  
Central Italy ◽  
Seismic Sequence ◽  
Fault Segmentation ◽  
Main Shocks

scholarly journals In search of evidence of deep fluid discharges and pore pressure evolution in the crust to explain the seismicity style of the Umbria-Marche 1997-1998 seismic sequence (Central Italy)

1999 ◽  
Vol 42 (4) ◽  
Author(s):  
F. Quattrocchi
Keyword(s):  
Pore Pressure ◽  
Frictional Heating ◽  
Central Italy ◽  
Frictional Stress ◽  
Seismic Sequence ◽  
Fluid Geochemistry ◽  
Main Shocks ◽  
Dehydration Reactions ◽  
Frictional Instability ◽  
Seismogenic Process

Starting soon after the first main-shocks of the long seismic sequence which has occurred along the Umbria-Marche boundary since September 1997, fluid geochemistry surveying was accomplished (around 200 samples) over the epicentre area as a whole, collecting information on hydrological variations too. The collected experimental data allowed to discuss the spatial and temporal evolution of the circulating fluids, either in the chemistry or in the dynamic paths, during the different stages of the seismic sequence. All the geo-structural, seismological and fluid geochemistry information gathered in this sector of the Central Apennines are discussed together in an attempt to speculate about the possible role and evolution of pore-pressure at depth up to surface within the seismogenic process recalling the "Fault Valve Activity Model", the "Coseismic Strain Model", the "frictional heating-frictional stress coupling model" and the "Dilatancy Model". This overview may also explain the geochemical and hydrological experimentally observed anomalies, in occurrence of the seismic sequence. The seismic style of the long sequence is revised in terms of pore-pressure regime down to seismogenic depth (2-10 km), within the poly-phase Evaporite Triassic Basement (ETB) and the Paleozoic Crystalline Basement (PCB), corresponding to the horizons of transient dehydration reactions: process triggered and enhanced during the seismogenic process, involving further fluid overpressure, and consequently further seismicity (chain effect). All the recalled processes and models may explain fluid remobilization and over-pressuring in the upper crust starting soon after the main-shocks, along relict low angle planes (close Apennine and anti-Apennine fault segments), rendering the Umbria-Marche boundary a "transiently weakened frictional instability zone", for a period spanning more than one year.

scholarly journals Heterogeneous Behavior of the Campotosto Normal Fault (Central Italy) Imaged by InSAR GPS and Strong-Motion Data: Insights from the 18 January 2017 Events

2019 ◽  
Vol 11 (12) ◽  
pp. 1482 ◽  
Author(s):  
Daniele Cheloni ◽  
Nicola D’Agostino ◽  
Laura Scognamiglio ◽  
Elisa Tinti ◽  
Christian Bignami ◽  
...  
Keyword(s):  
Central Italy ◽  
Sampling Rate ◽  
Strong Motion ◽  
Normal Fault ◽  
Slip Distribution ◽  
Fault System ◽  
Time Interval ◽  
Seismic Sequence ◽  
Main Shocks ◽  
Heterogeneous Behavior

On 18 January 2017, the 2016–2017 central Italy seismic sequence reached the Campotosto area with four events with magnitude larger than 5 in three hours (major event MW 5.5). To study the slip behavior on the causative fault/faults we followed two different methodologies: (1) we use Interferometric Synthetic Aperture Radar (InSAR) interferograms (Sentinel-1 satellites) and Global Positioning System (GPS) coseismic displacements to constrain the fault geometry and the cumulative slip distribution; (2) we invert near-source strong-motion, high-sampling-rate GPS waveforms, and high-rate GPS-derived static offsets to retrieve the rupture history of the two largest events. The geodetic inversion shows that the earthquake sequence occurred along the southern segment of the SW-dipping Mts. Laga normal fault system with an average slip of about 40 cm and an estimated cumulative geodetic moment of 9.29 × 1017 Nm (equivalent to a MW~6). This latter estimate is larger than the cumulative seismic moment of all the events, with MW > 4 which occurred in the corresponding time interval, suggesting that a fraction (~35%) of the overall deformation imaged by InSAR and GPS may have been released aseismically. Geodetic and seismological data agree with the geological information pointing out the Campotosto fault segment as the causative structure of the main shocks. The position of the hypocenters supports the evidence of an up-dip and northwestward rupture directivity during the major shocks of the sequence for both static and kinematic inferred slip models. The activated two main slip patches are characterized by rise time and peak slip velocity in the ranges 0.7–1.1 s and 2.3–3.2 km/s, respectively, and by ~35–50 cm of slip mainly concentrated in the shallower northern part of causative fault. Our results show that shallow slip (depth < 5 km) is required by the geodetic and seismological observations and that the inferred slip distribution is complementary with respect to the previous April 2009 seismic sequence affecting the southern half of the Campotosto fault. The recent moderate strain-release episodes (multiple M~5–5.5 earthquakes) and the paleoseismological evidence of surface-rupturing events (M~6.5) suggests therefore a heterogeneous behavior of the Campotosto fault.

Spatio-temporal seismic velocity variations associated to the 2016–2017 central Italy seismic sequence from noise cross-correlation

2019 ◽  
Vol 219 (3) ◽  
pp. 2165-2173
Author(s):  
Gaia Soldati ◽  
Lucia Zaccarelli ◽  
Licia Faenza
Keyword(s):  
Seismic Waves ◽  
Seismic Velocity ◽  
Linear Trend ◽  
Central Italy ◽  
Fault System ◽  
Seismic Sequence ◽  
Sedimentary Deposits ◽  
Main Shocks ◽  
Spatio Temporal ◽  
Velocity Changes

SUMMARY We investigate the temporal changes of crustal velocity associated to the seismic sequence of 2016–2017, which struck central Italy with a series of moderate to large earthquakes. We cross-correlate continuous recordings of 2 yr of ambient seismic noise from a network of 28 stations within a radius of 90 km around Amatrice town. We then map the spatio-temporal evolution of the velocity perturbations under the effect of subsequent earthquakes. Coinciding with each of the three main shocks of the sequence we observe a sudden drop of seismic velocity which tends to quickly recover in the short term. After the end of the strongest activity of the sequence, the coseismic velocity changes display gradual healing towards pre-earthquake conditions following a quasi-linear trend, such that by the end of 2017 about 75 per cent of the perturbation is recovered. The spatial distribution of the velocity drop fluctuates with time, and the area that shows the most intense variations beyond the ruptured fault system elongates in the NE direction. This zone roughly corresponds to a region of foredeep sedimentary deposits consisting of highly hydrated and porous sandstones, which respond to the passage of seismic waves with increased pore pressure and crack number, leading to a reduction of the effective relative velocity.

Ground effects and surface faulting in the September–October 1997 Umbria–Marche (Central Italy) seismic sequence

2000 ◽  
Vol 29 (3-5) ◽  
pp. 535-564 ◽  
Author(s):  
E Vittori ◽  
G Deiana ◽  
E Esposito ◽  
L Ferreli ◽  
L Marchegiani ◽  
...  
Keyword(s):  
Central Italy ◽  
Seismic Sequence ◽  
Ground Effects

Impact of landslides on transportation routes during the 2016–2017 Central Italy seismic sequence

Landslides ◽  
2019 ◽  
Vol 16 (6) ◽  
pp. 1221-1241 ◽  
Author(s):  
S. Martino ◽  
F. Bozzano ◽  
P. Caporossi ◽  
D. D’Angiò ◽  
M. Della Seta ◽  
...  
Keyword(s):  
Central Italy ◽  
Seismic Sequence ◽  
Transportation Routes

scholarly journals Failure Analysis of Apennine Masonry Churches Severely Damaged during the 2016 Central Italy Seismic Sequence

Buildings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 58 ◽  
Author(s):  
Francesco Clementi
Keyword(s):  
Case Studies ◽  
Central Italy ◽  
Numerical Data ◽  
Sensitivity Study ◽  
Nonlinear Material ◽  
Seismic Sequence ◽  
Nonlinear Approach ◽  
Nonlinear Static ◽  
Masonry Churches ◽  
Global And Local

This paper presents a detailed study of the damages and collapses suffered by various masonry churches in the aftermath of the seismic sequence of Central Italy in 2016. The damages will first be analyzed and then compared with the numerical data obtained through 3D simulations with eigenfrequency and then nonlinear static analyses (i.e., pushover). The main purposes of this study are: (i) to create an adequately consistent sensitivity study on several definite case studies to obtain an insight into the role played by geometry—which is always unique when referred to churches—and by irregularities; (ii) validate or address the applicability limits of the more widespread nonlinear approach, widely recommended by the Italian Technical Regulations. Pushover analyses are conducted assuming that the masonry behaves as a nonlinear material with different tensile and compressive strengths. The consistent number of case studies investigated will show how conventional static approaches can identify, albeit in a qualitative way, the most critical macro-elements that usually trigger both global and local collapses, underlining once again how the phenomena are affected by the geometry of stones and bricks, the texture of the wall face, and irregularities in the plan and elevation and in addition to hypotheses made on the continuity between orthogonal walls.

scholarly journals The Key Reason of False Positive Misclassification for Accurate Large-Area Mangrove Classifications

2021 ◽  
Vol 13 (15) ◽  
pp. 2909
Author(s):  
Chuanpeng Zhao ◽  
Cheng-Zhi Qin
Keyword(s):  
False Positive ◽  
Classification Scheme ◽  
Abundant Species ◽  
Google Earth ◽  
Large Area ◽  
Local Characteristics ◽  
Current Classification ◽  
Standard Classification ◽  
Selected Subset ◽  
Time Series Images

Accurate large-area mangrove classification is a challenging task due to the complexity of mangroves, such as abundant species within the mangrove category, and various appearances resulting from a large latitudinal span and varied habitats. Existing studies have improved mangrove classifications by introducing time series images, constructing new indices sensitive to mangroves, and correcting classifications by empirical constraints and visual inspections. However, false positive misclassifications are still prevalent in current classification results before corrections, and the key reason for false positive misclassification in large-area mangrove classifications is unknown. To address this knowledge gap, a hypothesis that an inadequate classification scheme (i.e., the choice of categories) is the key reason for such false positive misclassification is proposed in this paper. To validate this hypothesis, new categories considering non-mangrove vegetation near water (i.e., within one pixel from water bodies) were introduced, which is inclined to be misclassified as mangroves, into a normally-used standard classification scheme, so as to form a new scheme. In controlled conditions, two experiments were conducted. The first experiment using the same total features to derive direct mangrove classification results in China for the year 2018 on the Google Earth Engine with the standard scheme and the new scheme respectively. The second experiment used the optimal features to balance the probability of a selected feature to be effective for the scheme. A comparison shows that the inclusion of the new categories reduced the false positive pixels with a rate of 71.3% in the first experiment, and a rate of 66.3% in the second experiment. Local characteristics of false positive pixels within 1 × 1 km cells, and direct classification results in two selected subset areas were also analyzed for quantitative and qualitative validation. All the validation results from the two experiments support the finding that the hypothesis is true. The validated hypothesis can be easily applied to other studies to alleviate the prevalence of false positive misclassifications.

scholarly journals Pixel- vs. Object-Based Landsat 8 Data Classification in Google Earth Engine Using Random Forest: The Case Study of Maiella National Park

2021 ◽  
Vol 13 (12) ◽  
pp. 2299
Author(s):  
Andrea Tassi ◽  
Daniela Gigante ◽  
Giuseppe Modica ◽  
Luciano Di Martino ◽  
Marco Vizzari
Keyword(s):  
Land Cover ◽  
National Park ◽  
Time Window ◽  
Central Italy ◽  
Google Earth ◽  
Data Cube ◽  
Landsat 8 ◽  
Change Analysis ◽  
Object Based ◽  
Google Earth Engine

With the general objective of producing a 2018–2020 Land Use/Land Cover (LULC) map of the Maiella National Park (central Italy), useful for a future long-term LULC change analysis, this research aimed to develop a Landsat 8 (L8) data composition and classification process using Google Earth Engine (GEE). In this process, we compared two pixel-based (PB) and two object-based (OB) approaches, assessing the advantages of integrating the textural information in the PB approach. Moreover, we tested the possibility of using the L8 panchromatic band to improve the segmentation step and the object’s textural analysis of the OB approach and produce a 15-m resolution LULC map. After selecting the best time window of the year to compose the base data cube, we applied a cloud-filtering and a topography-correction process on the 32 available L8 surface reflectance images. On this basis, we calculated five spectral indices, some of them on an interannual basis, to account for vegetation seasonality. We added an elevation, an aspect, a slope layer, and the 2018 CORINE Land Cover classification layer to improve the available information. We applied the Gray-Level Co-Occurrence Matrix (GLCM) algorithm to calculate the image’s textural information and, in the OB approaches, the Simple Non-Iterative Clustering (SNIC) algorithm for the image segmentation step. We performed an initial RF optimization process finding the optimal number of decision trees through out-of-bag error analysis. We randomly distributed 1200 ground truth points and used 70% to train the RF classifier and 30% for the validation phase. This subdivision was randomly and recursively redefined to evaluate the performance of the tested approaches more robustly. The OB approaches performed better than the PB ones when using the 15 m L8 panchromatic band, while the addition of textural information did not improve the PB approach. Using the panchromatic band within an OB approach, we produced a detailed, 15-m resolution LULC map of the study area.

Sign in / Sign up

Export Citation Format

Share Document