scholarly journals Brief communication: Co-seismic displacement on 26 and 30 October 2016 (<i>M</i><sub>w</sub> = 5.9 and 6.5) – earthquakes in central Italy from the analysis of a local GNSS network

2017 ◽  
Vol 17 (11) ◽  
pp. 1885-1892 ◽  
Author(s):  
Giorgio De Guidi ◽  
Alessia Vecchio ◽  
Fabio Brighenti ◽  
Riccardo Caputo ◽  
Francesco Carnemolla ◽  
...  

Abstract. On 24 August 2016 a strong earthquake (Mw = 6.0) affected central Italy and an intense seismic sequence started. Field observations, DInSAR (Differential INterferometry Synthetic-Aperture Radar) analyses and preliminary focal mechanisms, as well as the distribution of aftershocks, suggested the reactivation of the northern sector of the Laga fault, the southern part of which was already rebooted during the 2009 L'Aquila sequence, and of the southern segment of the Mt Vettore fault system (MVFS). Based on this preliminary information and following the stress-triggering concept (Stein, 1999; Steacy et al., 2005), we tentatively identified a potential fault zone that is very vulnerable to future seismic events just north of the earlier epicentral area. Accordingly, we planned a local geodetic network consisting of five new GNSS (Global Navigation Satellite System) stations located a few kilometres away from both sides of the MVFS. This network was devoted to working out, at least partially but in some detail, the possible northward propagation of the crustal network ruptures. The building of the stations and a first set of measurements were carried out during a first campaign (30 September and 2 October 2016). On 26 October 2016, immediately north of the epicentral area of the 24 August event, another earthquake (Mw = 5.9) occurred, followed 4 days later (30 October) by the main shock (Mw = 6.5) of the whole 2016 summer–autumn seismic sequence. Our local geodetic network was fully affected by the new events and therefore we performed a second campaign soon after (11–13 November 2016). In this brief note, we provide the results of our geodetic measurements that registered the co-seismic and immediately post-seismic deformation of the two major October shocks, documenting in some detail the surface deformation close to the fault trace. We also compare our results with the available surface deformation field of the broader area, obtained on the basis of the DInSAR technique, and show an overall good fit.

Author(s):  
Giorgio De Guidi ◽  
Alessia Vecchio ◽  
Fabio Brighenti ◽  
Riccardo Caputo ◽  
Francesco Carnemolla ◽  
...  

Abstract. On October 26th 2016, immediately north of the epicentral area affected by the Mw 6.0, August 24th earthquake, a strong earthquake (Mw = 5.9), with a focal mechanism showing W-dipping normal faulting, occurred at the boundary between Marche and Umbria regions (central Apennines, Italy). Four days later (on October 30th), the main-shock (Mw = 6.5) of the whole seismic sequence occurred in the same area. The central Apennines are characterized by northeast-verging thrust-propagation folds, involving Mesozoic- Tertiary sedimentary successions. During the 2016 sequence, coseismic deformation has been recorded at the rear of the Sibillini Thrust which separates the main mountain chain from the Marche-Abruzzi foothills (Fig. 1). This contractional structure has been partly dissected and/or inverted by NNW-SSE trending Quaternary normal and oblique-slip faults. The major event (October 30) induced extensive geological effects at the surface and structural damages in the broader epicentral area up to a distance of 30 km. According to the report of the Istituto Nazionale di Geofisica e Vulcanologia (SUMMARY REPORT ON THE 30 OCTOBER, 2016 EARTHQUAKE IN CENTRAL ITALY Mw 6.5, Gruppo di Lavoro INGV sul Terremoto in centro Italia 10 November 2016), the hypocenter of major event was located at 42.8322° N, 13.1107° E at a depth of 9.2 km (Figs. 1 and 2). Following the August seismic events, we installed five new geodetic points located on both sides of the principal fracture zone and carried out two campaigns of GNSS measurements, the first one at the end of September (30-09/02-10, 2016), the second one early November (11/13-11, 2016) that covered the period of the October events. In this brief communication, we provide the results of our geodetic campaigns that registered the co- seismic displacement occurred in the period between doy (day of year) 2016/274 and doy 2016/318, therefore documenting the two latter major shocks. We also compare our results with the available surface deformation field of the broader area obtained on the basis of the DInSAR technique and particularly the elaboration realized by CNR-IREA of Sentinel-1 radar imaging of Copernicus European Program of 26/10–1/11 (http://www.irea.cnr.it/index.php?option=com_k2&amp;view=item&amp;id=761:nuovi-risultati-sul-terremoto- del-30-ottobre-2016-ottenuti-dai-radar-dei-satelliti-sentinel-1). The comparison shows an overall good fit. It’s worth to note that these earthquakes occurred in a sector of the Central Apennines characterized by high geodetic strain-rates (e.g., D’Agostino 2014), where several continuous GNSS stations are operating.


2020 ◽  
Vol 10 (18) ◽  
pp. 6445 ◽  
Author(s):  
Theodoros Gatsios ◽  
Francesca Cigna ◽  
Deodato Tapete ◽  
Vassilis Sakkas ◽  
Kyriaki Pavlou ◽  
...  

The Methana volcano in Greece belongs to the western part of the Hellenic Volcanic Arc, where the African and Eurasian tectonic plates converge at a rate of approximately 3 cm/year. While volcanic hazard in Methana is considered low, the neotectonic basin constituting the Saronic Gulf area is seismically active and there is evidence of local geothermal activity. Monitoring is therefore crucial to characterize any activity at the volcano that could impact the local population. This study aims to detect surface deformation in the whole Methana peninsula based on a long stack of 99 Sentinel-1 C-band Synthetic Aperture Radar (SAR) images in interferometric wide swath mode acquired in March 2015–August 2019. A Multi-Temporal Interferometric SAR (MT-InSAR) processing approach is exploited using the Interferometric Point Target Analysis (IPTA) method, involving the extraction of a network of targets including both Persistent Scatterers (PS) and Distributed Scatterers (DS) to augment the monitoring capability across the varied land cover of the peninsula. Satellite geodetic data from 2006–2019 Global Positioning System (GPS) benchmark surveying are used to calibrate and validate the MT-InSAR results. Deformation monitoring records from permanent Global Navigation Satellite System (GNSS) stations, two of which were installed within the peninsula in 2004 (METH) and 2019 (MTNA), are also exploited for interpretation of the regional deformation scenario. Geological, topographic, and 2006–2019 seismological data enable better understanding of the ground deformation observed. Line-of-sight displacement velocities of the over 4700 PS and 6200 DS within the peninsula are from −18.1 to +7.5 mm/year. The MT-InSAR data suggest a complex displacement pattern across the volcano edifice, including local-scale land surface processes. In Methana town, ground stability is found on volcanoclasts and limestone for the majority of the urban area footprint while some deformation is observed in the suburban zones. At the Mavri Petra andesitic dome, time series of the exceptionally dense PS/DS network across blocks of agglomerate and cinder reveal seasonal fluctuation (5 mm amplitude) overlapping the long-term stable trend. Given the steepness of the slopes along the eastern flank of the volcano, displacement patterns may indicate mass movements. The GNSS, seismological and MT-InSAR analyses lead to a first account of deformation processes and their temporal evolution over the last years for Methana, thus providing initial information to feed into the volcano baseline hazard assessment and monitoring system.


2021 ◽  
Vol 112 (1) ◽  
pp. 47-57
Author(s):  
Violetta Sokoła-Szewioła ◽  
Zbigniew Siejka

Abstract The problem involving the monitoring of surface ground movements in post-mining areas is particularly important during the period of mine closures. During or after flooding of a mine, mechanical properties of the rock mass may be impaired, and this may trigger subsidence, surface landslides, uplift, sinkholes or seismic activity. It is, therefore, important to examine and select updating methods and plans for long-term monitoring of post-mining areas to mitigate seismic hazards or surface deformation during and after mine closure. The research assumed the implementation of continuous monitoring of surface movements using the Global Navigation Satellite System (GNSS) in the area of a closed hard coal mine ‘Kazimierz-Juliusz’, located in Poland. In order to ensure displacement measurement results with the accuracy of several millimetres, the accuracy of multi-GNSS observations carried out in real time as a combination of four global navigation systems, Global Positioning System (GPS), Globalnaja Navigacionnaja Sputnikova Sistema (GLONASS), Galileo and BeiDou, was determined. The article presents the results of empirical research conducted at four reference points. The test observations were made in variants comprising measurements based on: GPS, GPS and GLONASS systems, GPS, GLONASS and Galileo systems, GPS, GLONASS, Galileo and BeiDou systems. For each adopted solution, daily measurement sessions were performed using the RTK technique. The test results were subjected to accuracy analyses. Based on the obtained results, it was found that GNSS measurements should be carried out with the use of three navigation systems (GPS, GLONASS, Galileo), as an optimal solution for the needs of continuous geodetic monitoring in the area of the study.


Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3646 ◽  
Author(s):  
Mariusz Specht ◽  
Cezary Specht ◽  
Andrzej Wilk ◽  
Władysław Koc ◽  
Leszek Smolarek ◽  
...  

Mobile Global Navigation Satellite System (GNSS) measurements carried out on the railway consist of using satellite navigation systems to determine the track geometry of a moving railway vehicle on a given route. Their purposes include diagnostics, stocktaking, and design work in railways. The greatest advantage of this method is the ability to perform measurements in a unified and coherent spatial reference system, which effectively enables the combining of design and construction works, as well as their implementation by engineering teams of diverse specialties. In the article, we attempted to assess the impact of using three types of work mode for a GNSS geodetic network [Global Positioning System (GPS), GPS/Global Navigation Satellite System (GLONASS) and GPS/GLONASS/Galileo] on positioning availability at three accuracy levels: 1 cm, 3 cm and 10 cm. This paper presents a mathematical model that enables the calculation of positioning availability at these levels. This model was also applied to the results of the measurement campaign performed by five GNSS geodetic receivers, made by a leading company in the field. Measurements with simultaneous position recording and accuracy assessment were taken separately on the same route for three types of receiver settings: GPS, GPS/GLONASS and GPS/GLONASS/Galileo in an urban area typical of a medium-sized city. The study has shown that applying a two-system solution (GPS/GLONASS) considerably increases the availability of high-precision coordinates compared to a single-system solution (GPS), whereas the measurements with three systems (GPS/GLONASS/Galileo) negligibly increase the availability compared to a two-system solution (GPS/GLONASS).


2020 ◽  
Vol 221 (1) ◽  
pp. 451-466 ◽  
Author(s):  
Qian Xu ◽  
Qiang Chen ◽  
Jingjing Zhao ◽  
Xianwen Liu ◽  
Yinghui Yang ◽  
...  

SUMMARY A 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.


2020 ◽  
Vol 12 (16) ◽  
pp. 2566
Author(s):  
Joaquín Escayo ◽  
José Fernández ◽  
Juan F. Prieto ◽  
Antonio G. Camacho ◽  
Mimmo Palano ◽  
...  

La Palma is one of the youngest of the Canary Islands, and historically the most active. The recent activity and unrest in the archipelago, the moderate seismicity observed in 2017 and 2018 and the possibility of catastrophic landslides related to the Cumbre Vieja volcano have made it strongly advisable to ensure a realistic knowledge of the background surface deformation on the island. This will then allow any anomalous deformation related to potential volcanic unrest on the island to be detected by monitoring the surface deformation. We describe here the observation results obtained during the 2006–2010 period using geodetic techniques such as Global Navigation Satellite System (GNSS), Advanced Differential Synthetic Aperture Radar Interferometry (A-DInSAR) and microgravimetry. These results show that, although there are no significant associated variations in gravity, there is a clear surface deformation that is spatially and temporally variable. Our results are discussed from the point of view of the unrest and its implications for the definition of an operational geodetic monitoring system for the island.


Author(s):  
Davide Fronzi ◽  
Francesca Banzato ◽  
Stefano Caliro ◽  
Costanza Cambi ◽  
Carlo Cardellini ◽  
...  

The dynamic of groundwater systems feeding several springs of the Sibillini Mountains was deeply affected by nine Mw 5.0÷6.5 seismic events occurred in central Italy starting from August 2016. The strongest shock occurred on October 30th 2016 about 5 km NNE of Norcia Town, 9 km below the surface, as a result of upper crust normal faulting on the nearly 30 km-long Mt Vettore - Mt Bove fault system, a NW-SE trending, SW-dipping fault system outcropping on the western slope of Mt Vettore, the highest peak of Sibillini Mountains. Soon after this event, a general increase of springs and rivers discharge and groundwater levels was observed both in the Visso and Norcia areas, west of the Sibillini Mountains. In the Visso area the hydrogeological changes due to the seismic sequence exhausted in the 2019, while nowadays both discharges and groundwater levels are still higher than before in the Norcia area. Discharge data of the main springs located east, south-east of the Sibillini Mountains were analysed to verify whether the general increase observed on the western side was associated to a decrease on the eastern and southern-east area. The results show that the springs located on the eastern side and southern-east side of Mt Vettore experienced a significant long-term discharge decrease. In this preliminary work, the analysis of the historical discharge series of the Pescara di Arquata spring (SE of Mt Vettore), and its relationship with the Standard Precipitation Index (SPI) shows that the very low discharge values recorded during the post-seismic period are not associated with SPI as low as documented in the past for similar discharges. Moreover, the stable isotopic composition of Pescara di Arquata water during the post-earthquake period is slightly different from that measured before the seismic events; this suggests that a lower amount of water having more enriched isotopic δ18O content reaches the spring after the seismic sequence. These aspects seem to indicate that groundwater circulation in the southern-east area of Sibillini Mountains has been affected by the 2016-2017 seismic sequence.


2019 ◽  
Vol 11 (4) ◽  
pp. 394 ◽  
Author(s):  
Gregorio Farolfi ◽  
Aldo Piombino ◽  
Filippo Catani

We present a detailed map of ground movement in Italy derived from the combination of the Global Navigation Satellite System (GNSS) and Satellite Synthetic Aperture Radar (SAR) interferometry. These techniques are two of the most used space geodetic techniques to study Earth surface deformation. The above techniques provide displacements with respect to different components of the ground point position; GNSSs use the geocentric International Terrestrial Reference System 1989 (ITRS89), whereas the satellite SAR interferometry components are identified by the Lines of Sight (LOSs) between a satellite and ground points. Moreover, SAR interferometry is a differential technique, and for that reason, displacements have no absolute reference datum. We performed datum alignment of InSAR products using precise velocity fields derived from GNSS permanent stations. The result is a coherent ground velocity field with detailed boundaries of velocity patterns that provide new information about the complex geodynamics involved on the Italian peninsula and about local movements.


2014 ◽  
Vol 1 (1) ◽  
pp. 70-93
Author(s):  
M. L. Ojigi ◽  
J. D. Dodo ◽  
Y. D. Opaluwa

The establishment of Earth Observation Satellite (EOS) ground receiving stations in parts of Nigeria and other parts of the globe, similar to the Indian Remote Sensing (IRS) model will enhance global telecommand, precise EOS tracking, data transmission, and distribution of NigeriaSat data, which will enhance global-scale data awareness, usage and higher financial returns for Nigeria. This study, therefore, attempts the application of Global Navigation Satellite System (GNSS) sky visibility planning and dilution of precision analysis technique to select the optimal location for EOS ground station(s) in Nigeria. The Nigerian Geodetic Network (NigNet) GNSS Continuously Operating Reference Stations (CORS) RINEX data of February 2012 and Trimble Total Control (TTC) software were used for the determinations of the baselines and positions of the 11 available CORS. The technique of GNSS sky visibility planning and dilution of precision (DOP) was adopted because signals from satellites behave in a similar pattern in the atmosphere, so poor visibility in GNSS signals in a particular observation window translates relatively to poor orbit definition signal for an EOS. Based on Jon's rating of DOP values [1= ideal; 2-3 = excellent; 4-6 =good; 7-8= moderate; 9-20=fair; 21-50= poor)], the DOP values for the stations across Nigeria can be adjudged to range between excellent and good for ground receiving stations. However, the overall results showed that GEMB on ellipsoidal heights of 1795.7857m has the most suitable DOPs and sky visibility plan for ground receiving sites followed by CGG Toro (916.7853m) and RAMPOLY Maiduguri (702m). The sky visibility analysis showed the availability of an average of 9 GPS and 2 GLONASS constellation satellites to receivers at elevation angles of 10°-15° between 6:00hrs and 24:00hrs daily across Nigeria. The approach of OS ground receiving station suitability analysts demonstrated in this study is recommended for the Nigerian. La mise en place de stations de réception au sol par satellite d'observation de la Terre (EOS) dans certaines parties du Nigeria et d'autres parties du globe, similaires au modèle indien de télédétection (IRS) améliorera la télécommande mondiale, le suivi EOS précis, la transmission de données et la distribution des données NigeriaSat. , ce qui améliorera la connaissance et l'utilisation des données à l'échelle mondiale et des rendements financiers plus élevés pour le Nigéria. Cette étude tente donc d'appliquer la planification de la visibilité du ciel du système mondial de navigation par satellite (GNSS) et la dilution de la technique d'analyse de précision pour sélectionner l'emplacement optimal pour la ou les stations au sol EOS au Nigéria. Les données RINEX des stations de référence en fonctionnement continu (CORS) du réseau géodésique nigérian (NigNet) GNSS de février 2012 et le logiciel Trimble Total Control (TTC) ont été utilisés pour déterminer les lignes de base et les positions des 11 CORS disponibles. La technique de planification de la visibilité du ciel GNSS et de dilution de la précision (DOP) a été adoptée car les signaux des satellites se comportent de manière similaire dans l'atmosphère, de sorte qu'une mauvaise visibilité des signaux GNSS dans une fenêtre d'observation particulière se traduit par un signal de définition d'orbite médiocre pour un EOS. . Basé sur l'évaluation des valeurs DOP de Jon [1 = idéal ; 2-3 = excellent ; 4-6 = bon ; 7-8= modéré ; 9-20=juste ; 21-50 = pauvre)], les valeurs DOP pour les stations à travers le Nigeria peuvent être estimées entre excellentes et bonnes pour les stations de réception au sol. Cependant, les résultats globaux ont montré que GEMB sur des hauteurs ellipsoïdales de 1795,7857m a les DOP et le plan de visibilité du ciel les plus appropriés pour les sites de réception au sol, suivis de CGG Toro (916,7853m) et RAMPOLY Maiduguri (702m). L'analyse de la visibilité du ciel a montré la disponibilité d'une moyenne de 9 satellites GPS et 2 satellites de la constellation GLONASS aux récepteurs à des angles d'élévation de 10° à 15° entre 6h00 et 24h00 tous les jours à travers le Nigeria. L'approche des analystes de l'adéquation des stations de réception au sol OS démontrée dans cette étude est recommandée pour le Nigérian.


2020 ◽  
Vol 12 (10) ◽  
pp. 1570
Author(s):  
Maya Ilieva ◽  
Łukasz Rudziński ◽  
Kamila Pawłuszek-Filipiak ◽  
Grzegorz Lizurek ◽  
Iwona Kudłacik ◽  
...  

On 29 January 2019, the collapse of a mine roof resulted in a significant surface deformation and generated a tremor with a magnitude of 4.6 in Rudna Mine, Poland. This study combines the seismological and geodetic monitoring of the event. Data from local and regional seismological networks were used to estimate the mechanism of the source and the ground motion caused by the earthquake. Global Navigation Satellite System data, collected at 10 Hz, and processed as a long-term time-series of daily coordinates solutions and short-term high frequency oscillations, are in good agreement with the seismological outputs, having detected several more tremors. The range and dynamics of the deformed surface area were monitored using satellite radar techniques for slow and fast motion detection. The radar data revealed that a 2-km2 area was affected in the six days after the collapse and that there was an increase in the post-event rate of subsidence.


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