A new strategy for the estimation of plume height from clast dispersal in various atmospheric and eruptive conditions

Rossi, Eduardo; Bonadonna, Costanza; Degruyter, Wim

doi:10.1016/j.epsl.2018.10.007

Cited by 37 publications

(41 citation statements)

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“…Sedimentation of large clasts is computed with the model described in [52] and applied for the first time at Etna [53]. The model has an approach similar to that presented in [54].…”

Section: Impact Of Large Clasts (≥ 5 Cm)mentioning

confidence: 99%

Near-Real-Time Tephra Fallout Assessment at Mt. Etna, Italy

et al. 2019

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During explosive eruptions, emergency responders and government agencies need to make fast decisions that should be based on an accurate forecast of tephra dispersal and assessment of the expected impact. Here, we propose a new operational tephra fallout monitoring and forecasting system based on quantitative volcanological observations and modelling. The new system runs at the Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo (INGV-OE) and is able to provide a reliable hazard assessment to the National Department of Civil Protection (DPC) during explosive eruptions. The new operational system combines data from low-cost calibrated visible cameras and satellite images to estimate the variation of column height with time and model volcanic plume and fallout in near-real-time (NRT). The new system has three main objectives: (i) to determine column height in NRT using multiple sensors (calibrated cameras and satellite images); (ii) to compute isomass and isopleth maps of tephra deposits in NRT; (iii) to help the DPC to best select the eruption scenarios run daily by INGV-OE every three hours. A particular novel feature of the new system is the computation of an isopleth map, which helps to identify the region of sedimentation of large clasts (≥5 cm) that could cause injuries to tourists, hikers, guides, and scientists, as well as damage buildings in the proximity of the summit craters. The proposed system could be easily adapted to other volcano observatories worldwide. medium lapilli has been widely considered as a primary risk agent related to explosive volcanic activity, fallout of coarse lapilli to small blocks falling from plume margins has been underrated. As an example, during the event at Etna on 23 November 2013, clasts from several centimeters to decimeters fell within 5-6 km from the summit and hit hikers who were in the touristic areas [8]. Although the assessment of tephra fallout and dispersal in distal areas has been largely considered [9][10][11][12], the reduction of volcanic impacts in proximal areas and within the first hour from the beginning of the eruption is still a challenge. As a matter of fact, regardless of the importance of this information for emergency responders and government agencies, the operational systems capable of monitoring tephra dispersal and fallout in near-real-time (NRT) and returning the expected impact assessment are still limited and not fully adapted to the growing requirements of precision and reliability.A good example of NRT tephra detection in volcano observatories is represented by the Alaska Volcano Observatory (AVO), which monitors volcanoes within the North Pacific region [13]. The AVO system analyzes data from different satellite sensors. They use a 24/7 automated ash cloud detection algorithm that sends emails and phone text alerts to the AVO members, who are, in turn, responsible for verifying if the automatic alert can be considered as true or false [13]. The Kamchatka Volcanic Eruption Response Team (KVERT) monitors 36 active volcanoes in ...

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“…Sedimentation of large clasts is computed with the model described in [52] and applied for the first time at Etna [53]. The model has an approach similar to that presented in [54].…”

Section: Impact Of Large Clasts (≥ 5 Cm)mentioning

confidence: 99%

Near-Real-Time Tephra Fallout Assessment at Mt. Etna, Italy

et al. 2019

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“…In fact, this event represents a lava fountain with one of the largest mass eruption rates at Mount Etna (Andronico et al, 2015;Bonaccorso et al, 2014). For samples collected following the event (Russo, 2016), both the median and the average of the five largest clasts (measured using the method of Bagheri and Bonadonna, 2016a) were calculated and the drag coefficients, k S and k N , were derived for use in the hazard analysis, as described in Appendix A. We found that the median is more stable than the average of the five largest clasts at the scale of the outcrop (Tables A1 and A2), as also concluded by Bonadonna et al (2013); however, isopleth maps compiled based on the median values (and corresponding downwind and crosswind ranges) are not more stable than the isopleth maps compiled based on the average of the five largest clasts (Fig.…”

Section: Field Observationsmentioning

confidence: 99%

“…The sensitivity of the model output to particle density was tested using simulations with particle densities selected from end member values measured at Mount Etna. In particular, we considered the events of 12 January 2011 (1000 kg m −3 ), 23 November 2013 (865 kg m −3 ) and 3 December 2015 (760 kg m −3 ) (Andronico et al, 2015(Andronico et al, , 2014Russo, 2016). The wind was fixed to 12 December 2015 from 14:00 to 16:00 UTC as for the particle number test.…”

Section: Particle Densitymentioning

confidence: 99%

“…Appendix A: Field survey analysis: median versus the average of the five largest clasts A detailed field survey was carried out by Russo (2016), who measured the three axes of 10 to 15 clasts in three different areas, each of 25 m 2 , at 16 locations at different distances from the vent. The equivalent diameter of each clast, d eq , was calculated using the following equation (Bagheri and Bonadonna, 2016a):…”

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Exposure-based risk assessment and emergency management associated with the fallout of large clasts at Mount Etna

Osman

Rossi

Bonadonna

et al. 2019

Nat. Hazards Earth Syst. Sci.

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Abstract. Fallout of ballistic blocks and bombs ejected from eruptive vents represents a well-known hazard in areas proximal to volcanoes (mostly <5 km from the vent). However, fallout of large clasts sedimenting from plume margins that extend to medial areas and have the potential to produce severe injuries to people and cause damage to infrastructure, is often overlooked. Recent eruptive events at Mount Etna (Italy) provide a clear example where large-clast fallout from plume margins (>5 cm) has posed a real threat both to the many visitors reaching the summit area and to local infrastructure, and, therefore, has been selected as a case study. To quantify this hazard, a new particle sedimentation model was calibrated with field data and then used for probabilistic hazard assessments. For a fully probabilistic scenario the hazard zone covered 72 km2 and included some 125 km of paths and roads, as well as 15 buildings. Evacuation on foot to a safe area was estimated at almost 4 h, but this could be reduced to less than 3 h if two shelters were provided. Our results show the importance of integrating probabilistic hazard analysis of large-clast fallout within effective strategies of risk management and reduction, especially in the case of volcanoes where visitors can reach the summit areas.

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“…Determining the Total Grain Size Distribution (TGSD) is an important challenge for the accurate simulation of volcanic ash dispersal and deposition (e.g. [73][74][75]), as the size (and density) of the particles controls terminal velocity which in turn affects the deposition patterns [76]. Usually the TGSD is determined by sampling a large amount of points along the dispersal axis of the volcanic cloud and, accounting for aggregation, reconstructing the original distribution at the plume.…”

Section: Total Grain Size Distribution Determinationmentioning

confidence: 99%

Experimental High-Resolution Forecasting of Volcanic Ash Hazard at Sakurajima, Japan

Poulidis¹,

Takemi²,

Iguchi³

2019

JDR

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A high-resolution forecast methodology for the ash hazard at Sakurajima volcano, Japan, is presented. The methodology employs a combined modeling approach and utilizes eruption source parameters estimated by geophysical observations from Sakurajima, allowing for a proactive approach in forecasting. The Weather Research and Forecasting (WRF) model is used to downscale Japan Meteorological Agency (JMA) forecast data over the area of interest. The high-resolution meteorological data are then used in FALL3D model to provide a forecast for the ash dispersal and deposition. The methodology is applied for an eruption that occurred on June 16, 2018. Disdrometer observations of ashfall are used along with ash dispersal modeling to inform the choice of the total grain size distribution (TGSD). A series of pseudo-forecast ash dispersal simulations are then carried out using the proposed methodology and estimated TGSD, initialized with meteorological forecast data released up to ∼13 hours before the eruption, with results showing surprising consistency up to ∼10 hours before the eruption. Using forecast data up to 4 hours before the eruption was seen to constrain observation to model ratios within a factor of 2–4 depending on the timing of simulation and location. A number of key future improvements for the methodology are also highlighted.

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A new strategy for the estimation of plume height from clast dispersal in various atmospheric and eruptive conditions

Cited by 37 publications

References 38 publications

Near-Real-Time Tephra Fallout Assessment at Mt. Etna, Italy

Near-Real-Time Tephra Fallout Assessment at Mt. Etna, Italy

Exposure-based risk assessment and emergency management associated with the fallout of large clasts at Mount Etna

Experimental High-Resolution Forecasting of Volcanic Ash Hazard at Sakurajima, Japan

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