scholarly journals The Contribution of Multi-Sensor Infrared Satellite Observations to Monitor Mt. Etna (Italy) Activity during May to August 2016

2018 ◽  
Vol 10 (12) ◽  
pp. 1948 ◽  
Author(s):  
Francesco Marchese ◽  
Marco Neri ◽  
Alfredo Falconieri ◽  
Teodosio Lacava ◽  
Giuseppe Mazzeo ◽  
...  
Keyword(s):  
Summit Crater ◽  
Satellite Observations ◽  
Fumarolic Activity ◽  
Landsat 8 ◽  
Surveillance Systems ◽  
Average Value ◽  
North East ◽  
The North ◽  
Strombolian Eruption ◽  
Mt Etna

In May 2016, three powerful paroxysmal events, mild Strombolian activity, and lava emissions took place at the summit crater area of Mt. Etna (Sicily, Italy). During, and immediately after the eruption, part of the North-East crater (NEC) collapsed, while extensive subsidence affected the Voragine crater (VOR). Since the end of the May eruptions, a diffuse fumarolic activity occurred from a fracture system that cuts the entire summit area. Starting from 7 August, a small vent (of ~20–30 m in diameter) opened up within the VOR crater, emitting high-temperature gases and producing volcanic glow which was visible at night. We investigated those volcanic phenomena from space, exploiting the information provided by the satellite-based system developed at the Institute of Methodologies for Environmental Analysis (IMAA), which monitors Italian volcanoes in near-real time by means of the RSTVOLC (Robust Satellite Techniques–volcanoes) algorithm. Results, achieved integrating Advanced Very High Resolution Radiometer (AVHRR) and Moderate Resolution Imaging Spectroradiometer (MODIS) observations, showed that, despite some issues (e.g., in some cases, clouds masking the underlying hot surfaces), RSTVOLC provided additional information regarding Mt. Etna activity. In particular, results indicated that the Strombolian eruption of 21 May lasted longer than reported by field observations or that a short-lived event occurred in the late afternoon of the same day. Moreover, the outcomes of this study showed that the intensity of fumarolic emissions changed before 7 August, as a possible preparatory phase of the hot degassing activity occurring at VOR. In particular, the radiant flux retrieved from MODIS data decreased from 30 MW on 4 July to an average value of about 7.5 MW in the following weeks, increasing up to 18 MW a few days before the opening of a new degassing vent. These outcomes, in accordance with information provided by Sentinel-2 MSI (Multispectral Instrument) and Landsat 8-OLI (Operational Land Imager) data, confirm that satellite observations may also contribute greatly to the monitoring of active volcanoes in areas where efficient traditional surveillance systems exist.

THE NORMALIZED DIFFERENCE VEGETATION INDEX AS AN INDICATOR OF DYNAMICS

2021 ◽  
Author(s):  
Haddad Amar ◽  
Beldjazia Amina ◽  
Kadi Zahia ◽  
Redjaimia Lilia ◽  
Rached-Kanouni Malika
Keyword(s):  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Climatic Factors ◽  
Mediterranean Ecosystems ◽  
Point Of View ◽  
Aleppo Pine ◽  
Landsat 8 ◽  
North East ◽  
The North ◽  
Pine Trees

Mediterranean ecosystems are considered particularly sensitive to climate change. Any change in climatic factors affects the structure and functioning of these ecosystems and has an influence on plant productivity. The main objective of this work is to characterize one of the Mediterranean ecosystems; the Chettaba forest massif (located in the North-East of Algeria) from a vegetation point of view and their link with monthly variations using Landsat 8 satellite images from five different dates (June 25, 2017, July 27, 2017, August 28, 2017, October 15, 2017). The comparison of NDVI values in Aleppo pine trees was performed using analysis of variance and the use of Friedman's non-parametric test. The Mann-Kendall statistical method was applied to the monthly distribution of NDVI values to detect any trends in the data over the study period. The statistical results of NDVI of Aleppo pine trees indicate that the maximum value is recorded in the month of June, while the lowest values are observed in the month of August where the species studied is exposed to periods of thermal stress.

scholarly journals Updated SO<sub>2</sub> emission estimates over China using OMI/Aura observations

2017 ◽  
Author(s):  
Maria-Elissavet Koukouli ◽  
Nicolas Theys ◽  
Jieying Ding ◽  
Irene Zyrichidou ◽  
Bas Mijling ◽  
...  
Keyword(s):  
Emission Inventory ◽  
Satellite Observations ◽  
So2 Emissions ◽  
Transport Modelling ◽  
So2 Emission ◽  
Bottom Up ◽  
Beijing Area ◽  
Entire Domain ◽  
North East ◽  
The North

Abstract. The main aim of this paper is to update existing sulphur dioxide (SO2), emission inventories over China using novel inversion techniques, state-of-the-art chemistry transport modelling (CTM), and satellite observations of SO2. Within the framework of the EU FP7 Monitoring and Assessment of Regional air quality in China using space Observations, MarcoPolo project, a new SO2 emission inventory over China was calculated using the CHIMERE v2013b CTM simulations, ten years of OMI/Aura total SO2 columns and the pre-existing Multi-resolution Emission Inventory for China (MEIC v1.2). It is shown that including satellite observations in the calculations increases the current bottom-up MEIC inventory emissions for the entire domain studied [102° to 132° E and 15° to 55° N] from 26.30 Tg/annum to 32.60 Tg/annum, with positive updates which are stronger in winter [~ 36 % increase]. New source areas where identified in the South West [25–35° N and 100–110° E] as well as in the North East [40–50° N and 120–130° E] of the domain studied as high SO2 levels were observed by OMI, resulting in increased emissions in the aposteriori inventory that do not appear in the original MEIC v1.2 dataset. Comparisons with the independent Emissions Database for Global Atmospheric Research, EDGAR v4.3.1, show a satisfying agreement since the EDGAR 2010 bottom-up database provides 33.30 Tg/annum of SO2 emissions. When studying the entire OMI/Aura time period [2005 to 2015 inclusive], it was shown that the SO2 emissions remain nearly constant before year 2010 with a drift of −0.51 ± 0.38 Tg/annum and show a statistically significant decline after year 2010 of −1.64 ± 0.37 Tg/Annum for the entire domain. Similar findings were obtained when focusing on the Greater Beijing Area [110° to 120° E and 30° to 40° N] with pre-2010 drifts of −0.17 ± 0.14 and post-2010 drifts of −0.47 ± 0.12 Tg/annum. The new SO2 emission inventory is publicly available and forms part of the official EU MarcoPolo emission inventory over China which also includes updated NOx, VOCs and PM emissions.

scholarly journals Magnetic signatures of subsurface faults on the northern upper flank of Mt Etna (Italy)

2021 ◽  
Vol 64 (1) ◽  
Author(s):  
Rosalba Napoli ◽  
Gilda Currenti ◽  
Antonino Sicali
Keyword(s):  
Source Parameters ◽  
Magma Ascent ◽  
Magnetic Survey ◽  
Tectonic Structures ◽  
Near Surface ◽  
North East ◽  
The North ◽  
3D Euler Deconvolution ◽  
Mt Etna ◽  
Structural Indices

A ground magnetic study was performed on the northern upper flank of Mt. Etna to provide new insights into subsurface volcano-tectonic structures. The high resolution magnetic survey was focused on the main structures of Piano delle Concazze, a large flat area dominated by the North- East crater and bounded by the rim of the Valle del Leone depression and the extremity of the North- East Rift. More than 2,500 measurements were gathered with a sampling step of about 3 m covering an area of about 0.2 km2. The total-intensity anomaly field shows the presence of intense South- North aligned maxima related to shallow geological structures affecting this area. Filtering techniques and 2.5D modeling have been applied for the determination of the magnetic source parameters. In order to distinguish the near surface structure, filters of the vertical derivatives, Butterworth high-pass and the tilt derivative were used. The 3D Euler deconvolution has been applied to estimate the depth and the structural indices of the causative sources. The calculated structural indices, that express the geometrical nature of the source, are in agreement with forward modeling. They show that the area is mainly affected by subvertical normal fault and the estimated depth of magnetic sources ranges between 10 m and 40 m. Our total field magnetic survey shows that characteristic magnetic anomalies are related to fault zones in the Piano delle Concazze that are well consistent with the local tectonics. The subsurface structures that have been detected allowed to delineate the general structural framework of the area. In particular, it was possible to clarify that these structures seem to be not deep rooted and consequently they can hardly act as preferential pathways for magma ascent.

scholarly journals Geothermal potential mapping of Northeast Morocco (Bekrane-Ahfir) using remote sensing data and GIS

2021 ◽  
Vol 234 ◽  
pp. 00093
Author(s):  
Intissar El Morabit ◽  
Soufiane Maimouni ◽  
Ahmed Fekri
Keyword(s):  
Remote Sensing ◽  
Active Sites ◽  
Remote Sensing Data ◽  
Landsat 8 ◽  
North East ◽  
The North ◽  
Hydrothermal Springs ◽  
Geothermal Potential ◽  
Geothermal Activity ◽  
Potential Mapping

Geothermal energy is part of the renewable energy mix. It is used for heating, air conditioning and sometimes even for the production of electricity. Prospecting for such a resource proves to be a difficult and capital-intensive task. To overcome this constraint, we have used remote sensing which is an adequate tool to guide the prospecting through the elaboration of hydrothermal resource potential maps at the level of zones that present a favorable potential for exploitation (hyper-tectonized sites, volcanic sites, faulted sites, sites with hot geological formations, seismic zones...). The objective of this work is to carry out a study on the North-East of Morocco (Berkane Province), in order to identify favorable sites for geothermal exploitation such as geologically and hydrogeologically active sites. The methodology adopted consists in processing the images of the OLI (Operational Land Imager) and TIRS (Thermal Infrared Sensor) sensors of the Landsat-8 satellite in order to extract spectral indices (Clay mineral Index and Ferrous mineral Index,) detecting a geothermal activity and the surface temperature map (LST) using muticriteria analysis method (MCA). ) in the north-eastern part of Morocco. The results obtained show an almost perfect concordance of the distribution of the above-mentioned indices, with the map of lineaments which are considered as heat drains from the depth to the surface. Moreover, a correct correlation was established during the validation of these results with the map of the inventory of hydrothermal springs identified in the study area.

Identifying multi-day to sub-daily supraglacial lake change in Greenland from Sentinel 2 and Landsat 8 imagery using Google Earth Engine

2021 ◽  
Author(s):  
Qiao Li ◽  
James Lea ◽  
Stephen Brough
Keyword(s):  
Google Earth ◽  
Landsat 8 ◽  
Lake Area ◽  
High Latitudes ◽  
Large Area ◽  
Large Lakes ◽  
North East ◽  
The North ◽  
Google Earth Engine ◽  
Sentinel 2

&lt;p&gt;Supraglacial lakes (SGLs) are a major component of Greenland&amp;#8217;s surface hydrology and mass balance. Monitoring their evolution at multi-day to sub-daily timescales has traditionally been performed by relatively low-resolution sensors such as MODIS Terra, though opportunities exist for using higher spatial resolution sensors at high latitudes.&lt;/p&gt;&lt;p&gt;In this study, we take advantage of frequent orbital crossovers of Sentinel 2 and Landsat 8 imagery at high latitudes to monitor lakes at multi-day to sub-day temporal resolution, and spatial resolutions up to/over an order of magnitude higher than MODIS Terra (10 m to 30 m, compared to ~250 m for MODIS Terra). Through leveraging the cloud computing resources of Google Earth Engine (GEE), we have developed a workflow to track the evolution of lakes for all available Sentinel 2 and Landsat 8 images over a melt season.&lt;/p&gt;&lt;p&gt;Our workflow builds on the approach of Moussavi et al. (2020) that was developed for Antarctica, implementing it within GEE to explore its sensitivity and suitability for application to the catchment of the North East Greenland Ice Stream (NEGIS) for the 2019 melt season. To improve the efficiency of analysis, we analyse 282 large lakes (&gt;0.125 km^2) that were previously identified through analysis of MODIS Terra imagery. All lake outlines are appended with image ID and lake area metadata to facilitate subsequent analysis, and allow each lake outline to be traced back to the original image that it was derived from. Our approach is able to monitor lake growth and drainage at unprecedented spatial and temporal resolutions over a large area, allowing the widespread characterization of seasonal lake evolution.&lt;/p&gt;

scholarly journals Mapping and evaluating kinematics and stress/strain field at active faults and fissures: a comparison between field and drone data at NE Rift, Mt Etna (Italy)

2021 ◽  
Author(s):  
Alessandro Tibaldi ◽  
Noemi Corti ◽  
Emanuela De Beni ◽  
Fabio Luca Bonali ◽  
Susanna Falsaperla ◽  
...  
Keyword(s):  
Stress Field ◽  
Best Practice ◽  
Ground Deformation ◽  
Active Faults ◽  
Normal Faults ◽  
Extension Rate ◽  
North East ◽  
The North ◽  
Mt Etna ◽  
Dyke Injection

Abstract. We collected drone data to quantify the kinematics at extensional fractures and normal faults, integrated this information with seismological data to reconstruct the stress field, and critically compared the results with previous fieldwork to assess the best practice. As key site, we analysed a sector of the North-East Rift of Mt Etna, an area affected by continuous ground deformation linked to gravity sliding of the volcano's eastern flank and dyke injection. The studied sector is characterized also by the existence of eruptive craters and fissures and lava flows. This work shows that this rift segment is affected by a series of NE-striking, parallel extensional fractures characterized by an opening mode along an average N105.7° vector. Normal faults strike parallel to the extensional fractures, although they tend to bend slightly when crossing topographic highs corresponding to pyroclastic cones. The extensional strain obtained by cumulating the net offset at extensional fractures with the fault heave gives a stretching ratio of 1.003 in the northeastern part of the study area and 1.005 in the southwestern part. Given a maximum age of 1614 yr AD for the offset lavas, we obtained an extension rate of 1.9 cm/yr for the last 406 yr. The stress field is characterised by a σHmin trending NW-SE. Results indicate that Structure-from-Motion photogrammetry applied to drone surveys allows to collect large amounts of data with a resolution of 2–3 cm, a detail comparable to field surveys. In the same amount of time, drone survey can allow to collect more data than classical fieldwork, especially in logistically difficult rough terrains.

scholarly journals Investigating Volcanic Plumes from Mt. Etna Eruptions of December 2015 by Means of AVHRR and SEVIRI Data

Sensors ◽  
2019 ◽  
Vol 19 (5) ◽  
pp. 1174 ◽  
Author(s):  
Francesco Marchese ◽  
Alfredo Falconieri ◽  
Carolina Filizzola ◽  
Nicola Pergola ◽  
Valerio Tramutoli
Keyword(s):  
Eruption Rate ◽  
Volcanic Plumes ◽  
Average Value ◽  
North East ◽  
Infrared Imager ◽  
Rapid Sequence ◽  
Eruptive Column ◽  
Mt Etna ◽  
First Time ◽  
Very High

In early December 2015, a rapid sequence of strong paroxysmal events took place at the Mt. Etna crater area (Sicily, Italy). Intense paroxysms from the Voragine crater (VOR) generated an eruptive column extending up to an altitude of about 15 km above sea level. In the following days, other minor ash emissions occurred from summit craters. In this study, we present results achieved by monitoring Mt. Etna plumes by means of RSTASH (Robust Satellite Techniques-Ash) algorithm, running operationally at the Institute of Methodologies for Environmental Analysis (IMAA) on Advanced Very High Resolution Radiometer (AVHRR) data. Results showed that RSTASH detected an ash plume dispersing from Mt. Etna towards Ionian Sea starting from 3 December at 08:40 UTC, whereas it did not identify ash pixels on satellite data of same day at 04:20 UTC and 04:40 UTC (acquired soon after the end of first paroxysm from VOR), due to a mixed cloud containing SO2 and ice. During 8–10 December, the continuity of RSTASH detections allowed us to estimate the mass eruption rate (an average value of about 1.5 × 103 kg/s was retrieved here), quantitatively characterizing the eruptive activity from North East Crater (NEC). The work, exploiting information provided also by Spinning Enhanced Visible and Infrared Imager (SEVIRI) data, confirms the important contribution offered by RSTASH in identifying and tracking ash plumes emitted from Mt. Etna, despite some operational limitations (e.g., cloud coverage). Moreover, it shows that an experimental RST product, tailored to SEVIRI data, for the first time used and preliminarily assessed here, may complement RSTASH detections providing information about areas mostly affected by volcanic SO2.

scholarly journals THE CONTRIBUTION OF REMOTE SENSING AND AEROMAGNETISM TO GOLD PROSPECTING: THE CASE OF THE MEIGANGA ZONE, CAMEROON

2021 ◽  
Vol 9 (5) ◽  
pp. 775-793
Author(s):  
Bien A Nwos Prisca-Gaelle ◽  
◽  
Mounchili Ibrahim ◽  
Apouamoun Yiagnigni Roland ◽  
Etoundi Jean ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Magnetic Anomaly ◽  
Structural Information ◽  
Landsat 8 ◽  
Similar Distribution ◽  
Ferrous Ions ◽  
Equatorial Anomaly ◽  
Local Maxima ◽  
North East ◽  
The North

In order to optimize gold prospecting in the Meiganga zone located in the Adamaoua region of Cameroon, aeromagnetic and remote sensing prospecting was carried out in the eastern and southern parts. The remote sensing approach on a Landsat 8 OLI/TIRS image highlighted areas of maximum gold concentration. Thus, ferric ion bearing minerals are located in the North-West, silicate minerals bearing ferrous ions are in the Centre while clay minerals are in the North-East and East. The principal component analysis revealed important structural information. The PCA Spatial Map (PC1, PC2, PC3) showed the plutonic formations composed of anatexis and anatexis granites, vegetation cover (at the date of image acquisition: February 22, 2019), areas of permanent water circulation or accumulation, and metamorphic and sedimentary formations namely gneisses, quartzites, schists and superficial clay formations. A Landsat SRTM (Shuttle Radar Topography Mission) image was also used to enhance the lineaments through the Sobel filter to highlight the geomorphological (cliffs, valleys, ...) and topographic (river network, ridge and drainage segment) structures. The aeromagnetic approach was also important. The study of the modified magnetic field (CM) showed 4 ranges: very high, high, medium and low. The Total Magnetic Anomalies (TMI) of the area are subdivided into 2 ranges large positive anomalies (221.1-103.0 nT) located in the lower part of NE-SW orientation, small positive anomalies (103.0-(-)89.7 nT) located in the upper part of NE-SW orientation. The reduced total magnetic anomaly at the equator shows a fairly similar distribution to the total magnetic anomaly with the large positive anomalies in almost the entire lower part. Superimposed on the geological map, Neoproterozoic pre- to syn-tectonic granitoids (C) are superimposed on the large positive anomalies and Neoproterozoic conglomerates, quartzites, sedimentary shales and volcanosedimentary rocks (A) and Neoproterozoic syn-tectonic granitoids (B) are superimposed on the large and small positive anomalies. The grid of the reduced residual equatorial anomaly (ARRE) confirms that the local geology is strongly magnetic (gneiss and quartzite). The filters of the derivatives allowed to establish a map of magnetic lineaments of major orientation N045° and minor orientation N130°. The horizontal gadient superimposed on the local maxima showed the presence of deep structures oriented NE-SW. The analytical signal superimposed on the local maxima highlights the metamorphic basement consisting of rocks with strong magnetism. The application of Euler deconvolution localizes the depth of the sources of linear anomalies.

Seismic and infrasound signals at Mt. Etna: Modeling the North-East crater conduit and its relation with the 2008–2009 eruption feeding system

2013 ◽  
Vol 254 ◽  
pp. 53-68 ◽  
Author(s):  
Mariangela Sciotto ◽  
Andrea Cannata ◽  
Stefano Gresta ◽  
Eugenio Privitera ◽  
Laura Spina
Keyword(s):  
Feeding System ◽  
North East ◽  
The North ◽  
Mt Etna
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