Home  ›  what caused mt etna to erupt in 2019

what caused mt etna to erupt in 2019

Written By Thursday, 7 April 2022 Add Comment Edit

i. Introduction

In the concluding decade, Unmanned Aerial Vehicles (UAVs) have become useful tools for natural hazard observation, monitoring and studying. In volcanic areas, they allow a wider observation from in a higher place compared to traditional fieldwork, with no risk for the operator; in addition, a UAV survey is cheaper and faster with respect to using a helicopter (another widespread tool in the context of volcanic monitoring). From 2017, the Istituto Nazionale di Geofisica due east Vulcanologia, Osservatorio Etneo (INGV-OE), Italy, began using UAVs every bit an essential tool both for lava menstruation monitoring and mapping and for visible and thermal observations of the meridian craters (De Beni et al., 2019). The Construction from Motion (SfM) technique allows obtaining orthoimages to map lava flows in a brusque time, of key importance to provide the data needed for civil protection purposes in order to face the emergency apace. On the other hand, it is also possible to obtain a georeferenced Digital Acme Model (DEM), useful to obtain lava flow volumes, as DEMs difference between pre- and mail-eruption surfaces, and every bit a consequence, the Mass Output Rate (MOR), one of the almost of import features of an eruption. The post-eruption topography, highlighted by the new DEM, has a significant influence on the propagation of new lava and pyroclastic flows, a fundamental aspect for adventure assessment and chance mitigation.

In this paper, we present the results of several UAV surveys fabricated during and after the 30 May – half-dozen June 2022 eruption of Etna volcano, Italy, projecting the acquired data in a wider temporal context, which starts from 1999. This eruption was characterized past 2 different lava flows emplaced in different sectors of the Valle del Bove area, at a distance ranging from 1 up to 2 km from each other. The Valle del Bove is a horseshoe-shape low W-E oriented, which opened well-nigh 9 ka ago (Branca et al., 2016; Calvari et al., 2013) in the due east flank of Etna volcano. This low is more than than 7 km broad in the eastern area and 2 km in the upper zone, where the difference in altitude is more than thousand thou, with walls that gradient between xx - 45°. The Valle Del Bove, characterized past steep slopes and rugged terrain, is generally non readily attainable, which fabricated mapping specially difficult both from the field besides as from remote because it is frequently covered past clouds. The two eruptive fissures opened among the most unsafe areas to attain by foot, with several open fractures and the possibility of rock falls, landslides and pyroclastic flows (Andronico et al., 2018; 2009). Taking this into business relationship, a detailed, high-resolution and frequent survey of the eruptive scenario could be satisfactorily carried out with the aid of UAVs.

Thank you to the images and videos taken on different days it was possible to monitor the evolution of the eruptive fissures, to map the lava flow field, to characterize the eruption from a geometrical point of view, defining surface area, volume and MOR and to evaluate the aggregating of proximal pyroclastic deposits. Furthermore, our high-resolution surveys allowed detailing the morpho-structural elements of the eruptive vents on the east of the New Due south-East Crater flank (2019). With these surveys, it was also possible to complete and better, in quality and precision, the lava flow map of the 24–27 December 2022 eruption (2019; Cannavò et al., 2019) that was made with satellite and helicopter images during that eruption. In addition to the map of the May 2022 and December 2022 eruptions, we also present a lava flows map including the last 21 years of effusive action on Etna, mapped both through the identical methodology represented hither, and through more traditional detection techniques, based on data caused on the ground with pocket GPS, orthoimages and satellite data (2005). The authors have been contributing to the monitoring action of the Cartography Laboratory of the Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo (MAP-LAB hereafter) since 2009, including the volcanic products mapping and their divulgation through a Geoportal (http://geodb.ct.ingv.it/geoportale/; De Beni & Proietti, 2010; Montalto et al., 2016). Because that the Geological Map of Etna Volcano (2011) shows the volcanics upward to 2007, update the map could prove useful for the scientific community.

With this paper, we wish too to demonstrate that UAVs have get an undeniable tool for lava flow mapping even if the applied methodology during the UAV survey is perhaps not the all-time practice to obtain reliable photogrammetric results (Huang et al., 2017), it is a good compromise, considering the extreme environmental atmospheric condition, as already shown in De Beni et al. (2019). Our approach could besides exist applied to tackle other environmental risks (for example landslides, floods, and avalanches) in mountainous or inaccessible areas producing valuable, authentic, and timely information to support emergency responses.

2. Methods

Mapping active lava flows is a principal source of information to document an ongoing eruption, and is crucial for decision makers when facing an eruptive crisis. Various data derives from a detailed lava flow map, i.east. location and morpho-structural characteristics of the vent, catamenia direction, areal extent and secondary analysis the thickness, volume and the effusion charge per unit. The quality and reliability of this data is the straight event of accurate and detailed mapping. In add-on, during long-lasting eruptions, near-continuous monitoring and mapping let documentation of the lava field growth and evolution and a better understanding of the lava transport and emplacement (Pedersen et al., 2017). The quality and timing of lava flow mapping have improved significantly thank you to UAVs and SfM techniques. Traditionally, it was necessary to use a helicopter and carry out a GPS field survey to depict a satisfactory map, which is both times consuming and requiring numerous staff.

Since 2015, a new team at INGV-OE has managed and operated a fleet of UAVs, comprising composed by 2 DJI Phantom 3 Pro, #1 DJI Phantom 4 Pro, #1 DJI Phantom 4 RTK, #ane DJI Mavic Pro and #ane DJI Mavic Enterprise Dual. These UAV models are comparable to very stable flight cameras, used to capture images and videos of eruptions following a manual or pre-calculated flight mission, the latter in a autonomous way, remotely piloted past an operator in the field.

Mapping of the lava catamenia of the Etna volcano eruption from xxx May to 6 June 2022 was performed with ten flights subdivided into four surveys (Figure 1 and Tabular array i), optimized by choosing different take-off points, in society to have a minimum horizontal and vertical distance, from the area to be surveyed, while maintaining appropriate safe distance. A series of pictures is taken during the flying on the basis of a 'timed shot' interval. Several factors touch the overall quality of the captured images, particularly the cruise speed and the flight height. The Structure-from-Move (SfM) algorithm imposes an overlap between consecutive images to be no less than 65%–lxx%. For volcanological chance monitoring a value of 25 cm/pixel may exist plenty, assuasive to fly very high, even more 200 k from the ground.

Figure 1. Lava menstruation map of 2017, 2022 and 2022 lava flows on a 2022 shaded relief (2019), coordinates refer to the WGS84 ellipsoid, the map projection is UTM (Zone 33N), equidistance profile lines 50 thou (brown lines). White plains indicate the v unlike take-off points, colored rectangle enclose the overflown area from each take-off bespeak. Full color polygon = summit lava flow; hatching polygon = flank lava menstruum; doted polygon = pyroclastic deposits. SdA = Schiena dell'Asino, BlV = Dais; TdF = Torre del Filosofo, RdV = Rocca della Valle, SEC = Due south Due east Crater, NSEC = New South East Crater, BN = Bocca Nuova, VOR = Voragine; NEC = North Eastward Crater.

Table 1. Survey overview table: coordinates refer to the WGS84 ellipsoid, the projection is UTM (Zone 33N), and elevations are orthometric.

Mapping the thirty May – vi June 2022 lava menses required the processing of XYZ aerial pictures, implying a very heavy photogrammetric workload. Agisoft PhotoScan was used to conduct out the SfM technique, obtaining the results presented hither (for more detail well-nigh SfM see appendix one).

The surveys made to map the May 2022 lava flows were carried out with notable operational difficulties since the elevation difference betwixt the emission point and the front was very high (almost 1300 m) and the lava catamenia had emplaced on a particularly steep topography. Nearly of the lava had flowed within the Valle del Bove for this reason the accept-off bespeak could merely be located close to the proximal surface area (Figure 1). In improver, it was not possible to position the ground control points due to the extremely rough terrain and the related danger. This problem could invalidates the results from a georeferencing point of view and every bit a consequence the accuracy of the mapping process and of the book adding. To overcome the difficulty, nosotros applied the bespeak cloud alignment technique, successfully adopted in 2022 (De Beni et al., 2019) using 3D Reshaper software. Nosotros aligned the indicate cloud obtained with the UAV surveys to the point cloud of a pre-eruption surface used every bit reference. The pre-eruption surface chosen among existing ones was the 2022 DEM (2019), the most recent and validated bachelor. It is a high-resolution, loftier vertical accurateness digital elevation model (DEM) derived from Pleiades satellite data covering an surface area of about 400 km2 with a spatial resolution of 2 m. The accuracy of the DEM is calculated using RMSE (Root Mean Foursquare Error) and following Mukherjee et al. (2015). RMSE exhibits on an average how far observed values deviate from the assumed truthful value, it is a single quantity characterizing the error surface. R M S East = [ due north − i ∑ i = one n ⁡ ( D E M r e f − D Eastward 1000 ) ii ] Thanks to the Agisoft Photoscan software the orthoimages of the lava period field accept been realized. Importing the orthoimages into GIS software (ArcGIS) immune for cartoon the lava boundaries. One time the lava has been mapped, information can be extracted such as the covered area and volume. Lava flow volumes can be estimated by two different approaches, namely planimetric and topographic, on the basis of the bachelor data (De Beni et al., 2019 and references within). The former consists of multiplying the mapped area by thickness, usually measured from the field. In this case, the accuracy depends on the uncertainties inherent in both flow mapping and thickness measurements (Albino et al., 2020). Thicknesses in the topographic method, considered more accurate than the planimetric one (Coltelli et al., 2007), are estimated past distinguishing between pre- and post-eruption surfaces derived from DEMs.

In this paper, it was necessary to use both techniques due to the lack of an updated pre-eruption surface of the south side of the Valle del Bove. In this area, one lava flow field was emplaced in March-April 2022 and some other in December 2022 (Figure 1). Unfortunately, the May 2022 lava flows followed exactly the aforementioned path of the previous issue. Confronting this background, all nosotros could do was to apply the planimetric approach and find a fashion to evaluate the lava flows thickness by exploiting bachelor information. The first pace was an accurate control of the exact location of the previous lava flows (2017 and 2018). After accurately mapping the May 2022 lava flow, using the orthoimages and the DEM obtained by the photogrammetric elaboration, we performed 6 profiles to measure the lava menses thickness. The May 2022 lava flow lasted at least 6 days, enabling a uncomplicated lava flow field to form (sensu Walker, 1971, 1973) whose emplacement and thickening is substantially governed past topography hence on changes in the slope. Assuming that the thickness of a simple lava field remains abiding on a surface with a abiding slope (Behncke et al., 2014), we have identified 5 sectors with a homogeneous slope within the area covered by the lava flow itself (Figure 2(A)). Past comparison the thickness variation in each geological cross sections with the lava flow map, it was possible to identify the overlap area of dissimilar lava flows and distinguish the dissimilar contributions to lava thickness (Figure two(B)). In this way, it is possible to evaluate the average thickness in each sector with a constant slope. Moreover, we assume that the morphology of the lava flows, characterized by channels, could be approximated by a tabular morphology if we locate the lava flow roof at a thickness equivalent at the medium value previously evaluated. In brief, the negative ones (with respect to the average) balance the positive morphologies that rise up from the average thickness. To evaluate the average thickness, we have isolated a complex polygon, resulting from the geological cross-section where the roof of the polygon is the 2022 lava period surface, and the basal surface was extrapolated from the outcrops along the section. Each complex polygon has subsequently been modified and reduced to an equivalent rectangle whose width is given past the lava flow width, where information technology is sectioned, and the elevation results dividing the circuitous polygon expanse by its width (Figure 2(C)).

Effigy ii. (A) slope map of the Due east wall of the Valle del Bove, obtained from 2022 DEM (2019) equidistance contour lines 50 m (grey lines). In that location are 5 sectors, inside the 2022 south lava flow, characterized past constant degree slope equally a consequence each sector have constant thickness. (B) Geological cantankerous sections. (C) The sketch explains the areal correspondence between the complex polygon and the equivalent rectangle corresponding at department iv.

The volume of the lava flow emplaced on the north side of the Valle del Bove was obtained by the topographic approach every bit differencing pre-eruption surface, the 2022 DEM (2019), and postal service-eruption surface from UAVs measurements. The May 2022 lava flow was emplaced in an area afflicted past a lava menses emitted during August 2018, and fortunately there is a negligible overlap between the two lava flows of about 3%. The volume was calculated using the ArcGIS Cut and Fill up tool from the following: V = ∑ i ⁡ Δ x two Δ z i where Δ x is the filigree jail cell side and Δ z i is the height difference between the mail service- and pre-eruption surfaces, for each pixel within the lava menstruation (De Beni et al., 2019). Errors on the book estimation have been calculated starting from the standard variance propagation law practical to the volume equation. The maximum error on the volume is linearly dependent on the standard deviation on the height variations ( σ Δ z ) calculated inside regions where no change occurred, performing height differences between the involved DEMs (2015 as pre- and 2022 as post-eruption; for more item on mistake calculation run into De Beni et al., 2019 and references therein).

Sadly, the DTM 2022 (2019) is affected past an error in the surface area covered by the lava front. For this reason, the volume of the lava front, almost 50% of the northern lava flow, has been calculated by interpolating a basal surface with the ArcGIS Natural Neighbor interpolation tool (De Beni et al., 2019). The basal surface was interpolated starting from a point shapefile, drawn five thousand exterior the lava menses boundary, whose XYZ coordinates come from the DEM derived by UAV.

3. Results

Cheers to 10 UAVs surveys, it was possible to compile a detailed map of lava flows and pyroclastic deposits emitted during the May 2022 eruption (Figure ane). Each survey enabled obtaining unlike products such as video or images that allow the ascertainment of the eruptive activity from to a higher place; moreover, the images take been processed with SfM to obtain orthoimages and DEMs at different stages of the eruption (Table 2).

Table two. summary table of the main products obtained from each survey and their characteristics, no data value in the DEM accurateness is due to the lack of a reference surface in the vent area.

The sharpness of the images taken during the eruption is low due to the amount of gas close to the vents making mapping difficult. To overcome this problem, nosotros performed several surveys on dissimilar days, with different levels of resolution and accurateness, which nosotros employ both to give timely information during the showtime emergency phases, and for more precise descriptions of the phenomena, performed with greater accuracy. For example, the orthoimages can identify portions of lava menses that were clearly visible when still hot and hence similar to previous ones when they cooled (Figure 3). Moreover, when the eruption is still ongoing vents are clearly visible. For a more reliable DEM processing and for an accurate volume adding, information technology is necessary to deport out surveys in 'calm conditions' to obtain clear images. The almost 300 images taken during the survey from Rocca della Valle have been elaborated in a single run covering the unabridged extension of the northern lava flow with 1.622 1000two. The orthoimages and DEM cell size are 0.05 and 1.07 k respectively. The eastern lava flow, slightly longer than the northern i, was covered with several surveys, undertaken on different days and with unlike lite and weather condition weather condition. The lava front end has been captured from the Schiena dell'Asino location (Figure 1); 69 images take been handled obtaining an orthoimage and a DEM with a cell size of 0.02 and ane.76 m respectively; the overflown area was 300,000 kii. The chief lava flow portion located on the east wall of the Valle del Bove and the proximal surface area take been overflowing from different places simply the 569 images take been run in a unmarried process roofing an area of 1,689,700 mii. The orthoimages and DEM cell size are 0.05 and 1.54 grand respectively. Orthoimages and shaded relief are visible in the main map with a magnification of the eruptive fissures areas. The northern fissure is composed of 2 sub-parallel NE-SW fractures, ranging from l up to 120 m in length; the southern i is elongated NW-SE and is characterized by 25 eruptive vents, having a diameter ranging from 0.3 upwardly to 20 m. All of the lava period field was mapped, obtaining a total lava field area of 0.nine × 10five m2, 6 and 3 ×105 mtwo in the east and in the north lava flows respectively. The book of the due south lava flow unit has been evaluated at two.9 ×10vi chiliadiii with the planimetric arroyo (Table 2). The volume of the north lava menstruum unit derives from the topographic arroyo at ane.5 ± 0.7 ×10vi m3 (Table 3).

Figure 3. Orthoimages of the vent obtained later the first ii surveys; the steam makes it hard to clearly identify some areas of the lava field but the vents are more visible thanks to the hot lava.

Table 3. Area and volume calculated for the northern lava flow and for its proximal pyroclastic deposit. σΔZ = standard departure on the height variations MAX = Maximum MIN = Minimum, N = total number of cells within the area.

Dividing the total volume past the duration of the 28 h, a mass output charge per unit (MOR) of 14.7 one thousandiii/s resulted for the northern lava period, while the eastern lava flow is characterized by a lower MOR of v.6 10003/s considering it lasted half-dozen days.

4. Discussion and conclusions

Mt Etna is one of the most agile volcanoes in the world – indeed, starting from 1999, we tin count about seventy eruptions with both meridian and flank-producing lava flows (Cappello et al., 2019). Therefore, knowledge of the eruptions means knowing where, how and when a lava flow emplaced. I of the tasks of the Cartography Laboratory (MAP-LAB) of the INGV-OE is to update a geo-database of the effusive activities. This geo-database is bachelor at http://geodb.ct.ingv.information technology/geoportale/ where lava menstruation maps tin be downloaded as WMP (Spider web Map Service).

Different approaches take normally been used to map lava flows in the field and remotely (from the air) on Etna. Ground-based surveys have ii disadvantages, namely potential danger to ground-based personnel and the frequently-limited accessibility to advancing lava flows and expanding flow fields (Calvari et al., 2003; Harris et al., 2007; Spampinato et al., 2011). Radar satellite data, on the other mitt, is safer and can provide a comprehensive assessment of the total lava flow field, essential when attempting to monitor flow fronts during volcanic eruptions. Nonetheless, it can exist hampered past the presence of clouds and is generally less authentic than footing measurements (2019; Ganci et al., 2016; 2015). UAVs offer a good compromise between reliable results and personnel prophylactic and were successfully tested on Etna in 2022 (De Beni et al., 2019), only the outset effort to use UAVs in an on-going lava flow mapping was made on the 2022 lava menstruum front end.

The map represents the 2022 erupted products in the context of the effusive activeness from 1999 to 2019. We take distinguished the summit lava flows emitted by the top craters, and the flank (or lateral) lava flows, generated by eruptive fissures on the flanks of the volcano.

More information regarding the lava flows emplaced from 1999 up to 2022 are available in Table 4. The full covered area past lava flows in this time interval is about 80 × 10half-dozen mii with a total volume of about 530 × tenhalf dozen m3. Lava flows are grouped past eruption years and divided between pinnacle and lateral or flank; it was possible to summate that in the last xxx years, the corporeality of volcanics emitted by the summit craters and lateral eruptions is almost the same, only the peak eruptions covered an expanse near three-times bigger than the lateral ones.

Table iv. Summary tabular array of the lava flows emplaced from 1999 upwardly to 2022 distinguished into tiptop and lateral or flank.

Ultimately, the map represents a useful upgrade to the cartography of volcanic products erupted by 1 of the most agile volcanoes in the earth, which continuously changes in shape and topographic heights, especially most its summit eruptive vents.

This near-continuous effusive action is fortunately not e'er dangerous merely offers an boggling spectacle for tourists, although the 2001 and 2002–2003 lava flows destroyed tourist facilities at high altitudes on the southern and northern flanks of the volcano, causing a blow to the local economic system. The presence of thousands of tourists every year and associated facilities imply that continuous monitoring activity is necessary and a thorough knowledge of the past and recent activity of the volcano is essential for both stakeholders and researchers. A necessary undertaking for both scientific and civil protection purposes, focused on the constant monitoring of a UNESCO Globe Heritage Site.

Software

DjI GSP was employed to plan the UAV surveys.

Images were elaborated with Agisoft Photoscan® one.2.3 to use SfM tecnique.

Leica Geosystem-Exagon 3DReshaper® allowed the alignment of bespeak clouds.

The vector/raster data and chief map were managed using Esri ArcGIS ® 10.3.1, with final editing performed using Corel Describe 2022 ®.

Autodesk Autocad eleven® was used to transform the circuitous polygon into a rectangle to evaluate the average lava flow thickness.

wiltdosed1998.blogspot.com

Source: https://www.tandfonline.com/doi/full/10.1080/17445647.2020.1854131

Related Posts

0 Response to "what caused mt etna to erupt in 2019"

Post a Comment

Subscribe to: Post Comments (Atom)

Iklan Atas Artikel

Iklan Tengah Artikel 1

Iklan Tengah Artikel 2

Iklan Bawah Artikel