Submarine and Subaerial Morphological Changes Associated with the 2014 Eruption at Stromboli Island

Stromboli is an active insular volcano located in the Southern Tyrrhenian Sea and its recent volcanic activity is mostly confined within the Sciara del Fuoco (SdF, hereafter), a 2-km wide subaerial–submarine collapse scar, which morphologically dominates the NW flank of the edifice. In August-November 2014, an effusive eruption occurred along the steep SdF slope, with multiple lava flows reaching the sea. The integration of multisensor remote sensing data, including lidar, photogrammetric, bathymetric surveys coupled with SAR amplitude images collected before and after the 2014 eruption enabled to reconstruct the dynamics of the lava flows through the main morphological changes of the whole SdF slope. Well-defined and steep-sided ridges were created by lava flows during the early stages of the eruption, when effusion rates were high, favoring the penetration into the sea of lava flows as coherent bodies. Differently, fan-shaped features were emplaced during the declining stage of the eruption or in relation to lava overflows and associated gravel flows, suggesting the prevalence of volcaniclastic breccias with respect to coherent lava flows. The estimated volume of eruptive products emplaced on the SdF slope during the 2014 eruption, accounts for about 3.7 × 106 m3, 18% of which is in the submarine setting. This figure is different with respect to the previous 2007 eruption at Stromboli, when a large lava submarine delta formed. This discrepancy can be mainly related to the different elevation of the main vents feeding lava flows during the 2007 eruption (around 400 m) and the 2014 eruption (around 650 m). Besides slope accretion, instability processes were detected both in the subaerial and submarine SdF slope. Submarine slope failure mobilized at least 6 × 105 m3 of volcaniclastic material, representing the largest instability event detected since the 2007 lava delta emplacement.

Remotely assessing tephra fall building damage and vulnerability: Kelud Volcano, Indonesia

Tephra from large explosive eruptions can cause damage to buildings over wide geographical areas, creating a variety of issues for post-eruption recovery. This means that evaluating the extent and nature of likely building damage from future eruptions is an important aspect of volcanic risk assessment. However, our ability to make accurate assessments is currently limited by poor characterisation of how buildings perform under varying tephra loads. This study presents a method to remotely assess building damage to increase the quantity of data available for developing new tephra fall building vulnerability models. Given the large number of damaged buildings and the high potential for loss in future eruptions, we use the Kelud 2014 eruption as a case study. A total of 1154 buildings affected by falls 1–10 cm thick were assessed, with 790 showing signs that they sustained damage in the time between pre- and post-eruption satellite image acquisitions. Only 27 of the buildings surveyed appear to have experienced severe roof or building collapse. Damage was more commonly characterised by collapse of roof overhangs and verandas or damage that required roof cladding replacement. To estimate tephra loads received by each building we used Tephra2 inversion and interpolation of hand-contoured isopachs on the same set of deposit measurements. Combining tephra loads from both methods with our damage assessment, we develop the first sets of tephra fall fragility curves that consider damage severities lower than severe roof collapse. Weighted prediction accuracies are calculated for the curves using K-fold cross validation, with scores between 0.68 and 0.75 comparable to those for fragility curves developed for other natural hazards. Remote assessment of tephra fall building damage is highly complementary to traditional field-based surveying and both approaches should ideally be adopted to improve our understanding of tephra fall impacts following future damaging eruptions.

Psychological Impact Of Mount Kelud Eruption On Children In (Ring 1) Desa Kebonrejo Village, Kepung, Kediri District; Qualitative Research

Children who are a vulnerable group in disasters need special attention to reduce the negative risk of their life. This qualitative research with a phenomenological approach was conducted on children who survived the Mount Kelud eruption. Referring to the research aim and after analyzing the data with Interpretative Phenomenology Analysis (IPA), 6 (six) themes were found, namely: feeling the need to pray a lot, feeling afraid if the kelud volcano erupts again, the more affection for parents, feeling afraid of death, feeling slopes Kelud is the land of birth, and feels uncomfortable in the refuge. From all the themes can be concluded that the children who survived the 2014 eruption of Mount Kelud still felt frightened by the condition of Mount Kelud that might erupt, making them more prayerful and happy to help their parents because they didn't want their parents to be difficult.

Comparing Simulations of Umbrella-Cloud Growth and Ash Transport with Observations from Pinatubo, Kelud, and Calbuco Volcanoes

The largest explosive volcanic eruptions produce umbrella clouds that drive ash radially outward, enlarging the area that impacts aviation and ground-based communities. Models must consider the effects of umbrella spreading when forecasting hazards from these eruptions. In this paper we test a version of the advection–dispersion model Ash3d that considers umbrella spreading by comparing its simulations with observations from three well-documented umbrella-forming eruptions: (1) the 15 June 1991 eruption of Pinatubo (Philippines); (2) the 13 February 2014 eruption of Kelud (Indonesia); and (3) phase 2 of the 22–23 April 2015 eruption of Calbuco (Chile). In volume, these eruptions ranged from several cubic kilometers dense-rock equivalent (DRE) for Pinatubo to about one tenth for Calbuco. In mass eruption rate (MER), they ranged from 108–109 kg s−1 at Pinatubo to 9–16 × 106 kg s−1 at Calbuco. For each case we ran simulations that considered umbrella growth and ones that did not. All umbrella-cloud simulations produced a cloud whose area was within ~25% of the observed cloud by the end of the eruption. By the eruption end, the simulated areas of the Pinatubo, Kelud, and Calbuco clouds were 851, 53.2, and 100 × 103 km2 respectively. These areas were 2.2, 2.2, and 1.5 times the areas calculated in simulations that ignored umbrella growth. For Pinatubo and Kelud, the umbrella simulations provided better agreement with the observed cloud area than the non-umbrella simulations. Each of these simulations extended 24 h from the eruption start. After the eruption ended, the difference in cloud area (umbrella minus non-umbrella) at Pinatubo persisted for many hours; at Kelud it diminished and became negative after 14 h and at Calbuco it became negative after ~23 h. The negative differences were inferred to result from the fact that non-umbrella simulations distributed ash over a wider vertical extent in the plume, and that wind shear spread the cloud out in multiple directions. Thus, for some smaller eruptions, wind shear can produce a larger cloud than might be produced by umbrella spreading alone.

Explosive Volcanic Eruption Powered by Water-Saturated Magma

Little seismic unrest preceded the 2014 eruption of a stratovolcano in Indonesia, which suggests that the eruption was kick-started internally by volatile-triggered overpressure.

Special Issue on Integrated Study on Mitigation of Multimodal Disasters Caused by Ejection of Volcanic Products: Part 2

Our research project titled “Integrated study on mitigation of multimodal disasters caused by ejection of volcanic products” began in 2014 under SATREPS (Science and Technology Research Partnership for Sustainable Development) and is now coming to an end in 2019. Indonesia has 127 active volcanoes distributed along its archipelago making it a high risk location for volcano-related disasters. The target volcanoes in our study are Guntur, Galunggung, Merapi, Kelud, and Semeru in Java, and Sinabung in North Sumatra. Guntur and Galunggung are currently dormant and are potentially high-risk volcanoes. Merapi generated pyroclastic flows along the Gendol River in 2010, which resulted in over 300 casualties and induced frequent lahars. New eruptive activity of Merapi began in 2018. The 2014 eruption of Kelud formed a gigantic ash plume over 17 km high, dispersing ash widely over the island of Java. Semeru continued minor eruptive activity, accompanying a risk of a dome collapse. The aim of our research includes disaster mitigation of the Sinabung volcano, whose eruption began to form a lava dome at its summit at the end of 2013, followed by frequent pyroclastic flows for approximately 4 years, and the deposits became the source of rain-triggered lahars. Our goal is to implement SSDM (Support System for Decision-Making), which would allow us to forecast volcano-related hazards based on scales and types of eruptions inferred from monitoring data. This special issue collects fundamental scientific knowledge and technology for the SSDM as output from our project. The SSDM is an integrated system of monitoring, constructed scenarios, forecasting scale of eruption, simulation of sediment movement and volcanic ash dispersion in the atmosphere. X-band radars newly installed by our project in Indonesia were well utilized for estimation of spatial distribution not only of rain fall in catchments but also of volcanic ash clouds. Finally, we hope the SSDM will continue to be utilized under a consortium in Merapi, which was newly established in collaboration with our projects, and extended to other volcanoes.