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Mount Semeru, one of the world's most active volcanoes, experiences frequent eruptions and at least one significant eruption annually. Traditional monitoring methods, constrained by the existing geodetic infrastructure, have been augmented by Interferometry Synthetic Aperture Radar (InSAR) technology. Previous InSAR applications in Indonesia have primarily relied on Line-of-Sight (LOS) displacement measurements, utilizing a single orbital geometry. This study breaks new applications by leveraging two orbital geometries of the Sentinel-1 satellite, advancing beyond conventional one-dimensional observations to generate comprehensive multidimensional displacement time series. This approach enables the precise capture of vertical, east-west, and north-south components of surface motion at Semeru volcano. Our findings underscore the critical role of multitrack InSAR data in providing a nuanced understanding of volcanic deformation. By encompassing all three displacement components, our methodology delivers a more detailed and accurate depiction of the volcano's dynamics. Although the 2.5D displacement model proves adequate in certain scenarios, the full three-dimensional analysis reveals its superiority in monitoring slow surface deformation. This study not only demonstrates the enhanced capabilities of InSAR in volcanic monitoring but also sets a precedent for its application in other high-risk volcanic and tectonic regions. Furthermore, our research emphasizes the value of integrating InSAR data with other monitoring techniques, like the Global Navigation Satellite System (GNSS), for cross-validation and accuracy enhancement. The synergy of these technologies offers a powerful tool for geoscientists, potentially enhancing our understanding of surface motion and contributing to more effective risk management in geologically active areas. [ABSTRACT FROM AUTHOR]

We propose a vast area in the middle of Lombok, Indonesia, dominated by hummock hills, is a debris avalanche deposit (DAD). We define this > 500 km2 area as Kalibabak DAD that may originate from Samalas volcano. No descriptions of the morphology, stratigraphy, mechanism, and age of this DAD have yet been reported; this contribution bridges this research gap. Here we present morphological and internal architecture analysis, radiocarbon dating, paleotopographic modeling, and numerical simulation of the DAD. We also present geospatial data e.g., topographical and geological maps, digital elevation models (DEMs), satellite imagery – in combination with stratigraphic data constructed from field surveys, archived data, and electrical resistivity data. Results show that the DAD was formed by a sector-collapse of Samalas volcano and covers an area of 535 km2, with a deposit width of 41 km and a runout distance up to 39 km from the source. The average deposit thickness is 28 m, reaching a measured local maximum of 58 m and a calculated volume of ~ 15 km3. Andesitic breccia boulders and a sandy matrix dominate the deposit. Using ShapeVolc, we reconstructed the pre-DAD paleotopography and then used the reconstructed DEM to model the debris avalanche using VolcFlow. The model provides an estimate of the flow characteristics, but the extent of the modelled deposit does not match the present-day deposit, for at least two reasons: (i) the lack of information on the previous edifice topography that collapsed, and (ii) limited understanding of how DADs translate across the landscape. Fourteen radiocarbon dating samples indicate that the DAD was emplaced between 7,000–2,600 BCE. The DAD's enormous volume, vast extent and poorly weathered facies strongly suggest that it was not triggered by a Bandai-type debris avalanche (solely phreatic eruption), but more likely by a Bezymianny-type (magmatic eruption). This event was potentially triggered by a sub-Plinian or Plinian eruption (high eruption column with umbrella-like cloud) dated ~ 3,500 BCE, which produced the Propok pumice fall deposits. [ABSTRACT FROM AUTHOR]

Volcanic eruptions have varied and complex impacts on small-scale livestock farming located in volcanic hazard-prone areas due to diverse stock, rearing, and feeding practices. The study was aimed to clarify the critical factors for designing forage recovery and sustainable livestock production in highrisk-prone areas of active volcanic mountains. A total of seventy-five ruminant livestock farmers located in the eruption-impacted areas of five active volcanoes were surveyed on flock size, rearing, and feeding practices. They were interviewed about their experiences of the eruption's impact on the animals, forage feed, and livestock mitigation regarding survival efforts. Forage plants and soil samples were collected to analyze dry matter and crude nutrient composition and estimate the botanical composition, biomass production, and carrying capacity. Results showed that there were five species of ruminant animals reared in small flock size (< 7 heads/farm): beef cattle, buffalo, horses, goat, and sheep. Beef cattle and goats were the most popular farm animals raised in different breeds, rearing, and feeding systems. The volcanic eruption caused animal loss and health problems due to exposure to volcanic materials, forage damages, and animal mitigation constraints, resulting in flock size decrease and economic loss. The impact of the eruption on farm animals and forage plants varied among the volcanoes due to diverse eruptive characteristics, stock breed, rearing, and feeding practices. Livestock farming recovery post-eruption depended largely on the survival flock and the regrowth of forage plants. In conclusion, sustainable beef cattle farming in volcanic hazard-prone areas might be realized by effective livestock mitigation efforts, selecting appropriate types of animals and rearing/feeding systems based on agroecological conditions, and improving forage capacity and survival rate during and posteruption. [ABSTRACT FROM AUTHOR]

Effective risk management requires accurate assessment of population exposure to volcanic hazards. Assessment of this exposure at the large-scale has often relied on circular footprints of various sizes around a volcano to simplify challenges associated with estimating the directionality and distribution of the intensity of volcanic hazards. However, to date, exposure values obtained from circular footprints have never been compared with modelled hazard footprints. Here, we compare hazard and population exposure estimates calculated from concentric radii of 10, 30 and 100 km with those calculated from the simulation of dome- and column-collapse pyroclastic density currents (PDCs), large clasts, and tephra fall across Volcanic Explosivity Index (VEI) 3, 4 and 5 scenarios for 40 volcanoes in Indonesia and the Philippines. We found that a 10 km radius—considered by previous studies to capture hazard footprints and populations exposed for VEI ≤ 3 eruptions—generally overestimates the extent for most simulated hazards, except for column collapse PDCs. A 30 km radius – considered representative of life-threatening VEI ≤ 4 hazards—overestimates the extent of PDCs and large clasts but underestimates the extent of tephra fall. A 100 km radius encapsulates most simulated life-threatening hazards, although there are exceptions for certain combinations of scenario, source parameters, and volcano. In general, we observed a positive correlation between radii- and model-derived population exposure estimates in southeast Asia for all hazards except dome collapse PDC, which is very dependent upon topography. This study shows, for the first time, how and why concentric radii under- or over-estimate hazard extent and population exposure, providing a benchmark for interpreting radii-derived hazard and exposure estimates. [ABSTRACT FROM AUTHOR]

Geologically speaking, Labuang Rano Village, Mamuju City area is composed of rocks from the Adang Volcano Formation. Based on the results of the site survey, it was found that there is a spring with a slight discharge. The emergence of these springs is not yet known, so further analysis is needed. An approach used to determine subsurface conditions is the geophysical approach, especially the geoelectric method. This study aims to analyse the subsurface geological conditions using geoelectric to find the factors that influence the emergence of springs. Geoelectrical measurements, observations of rock outcrops, and the findings of previous research are used as data sources. The results of the analysis show that the subsurface geological conditions consist of 3 layers. The topmost layer is tuff rock, the 2nd layer is volcanic breccia and the 3rd layer is andesite rock. Based on the resistivity cross-section, it can be seen that there is a fracture that cuts vertically in the tufa rock layer from a depth of 13 m to the surface in a northeast-southwest direction. Thus, it can be concluded that the emergence of springs at the study site was caused by a fracture that cut the tufa rock layers vertically from a depth of 13 to the surface. The fracture which is the medium for groundwater to emerge onto the land surface forms a spring. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Governance & Administrative Reform is the property of Universitas Airlangga and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

On 22 December 2018, the major flank collapse of Anak Krakatau volcano generated a tsunami that struck the surrounding coasts of Java and Sumatra islands in Indonesia without warning. It was later suggested that the corresponding seismic event lacked the body-wave arrivals typical of tectonic earthquakes, causing difficulties for the automated detection system to recognize the event. We explore the possibility of detecting the seismic signature of such events without relying on the arrival times of body waves, by measuring seismic amplitudes in a regional seismic network at the expected arrival times from a fixed, potential source and comparing them to the theoretical attenuation of surface waves. We propose a fast detection method and evaluate the method using seismograms recorded during the flank collapse and tsunami episode as well as several known tectonic earthquakes. Detailed examinations of the detection results confirm the seismic signatures of the flank collapse and teleseismic events as suggested by previous studies. We also find more seismic signatures suggesting the occurrence of two possible smaller collapse events and variations in the eruptive activity related to the major flank collapse, as well as body and surface wave signals from two teleseismic earthquakes that were present during this episode. Finally, we construct a timeline of events during this devastating episode, combining our results with previous studies as well as insights from weather radar observations. With the ability to detect and discriminate various types of seismic events from each other, the detection method can be useful in assisting the existing monitoring and early warning systems in detecting major volcano-related tsunamigenic events. [ABSTRACT FROM AUTHOR]

Indonesia is surrounded by three tectonic plates: the Eurasian, Indo−Australian, and Pacific plates. The plates have caused Indonesia to have many volcanoes, both active and inactive, resting, or no longer active. One of the volcanoes belonging to the formed “Rest” category is the ancient Lawu volcano. The mountain is 10,000 radiocarbon years old or approximately 11,430 ​± ​130 calendar years ago, which is part of the Holocene age. The Lawu volcano erupted on November 28, 1885. This paper discusses the study of magnetic minerals in the case of pyroclastic flows originating from Mount Lawu. The values obtained in magnetic susceptibility are 47.53 ​× ​10−6 ​m³/kg to 79.41 ​× ​10−6 ​m³/kg. The results of this susceptibility measurement indicate the presence of igneous rocks resulting from pyroclastic flow. Furthermore, the vibrating sample magnetometer test showed an S−type (ferromagnetic) hysteresis curve, and the value of Mr/Ms (remanence ratio) define was below 0.5, which realized a multi-domain configuration. This ferromagnetic characteristic is attributed to the iron-based mineral (10.4%–17.1%) from the evaluation of X−Ray Fluorescence. The magnetite mineral confirmed in the X-Ray Diffractometer test is the largest source of magnetism in the sample. [ABSTRACT FROM AUTHOR]

Texture and particularly compositional variations of zoned minerals are important to understand trans-crustal magma plumbing systems of volcanoes. The Sipisupisu volcano in Sunda arc, northern Sumatra, occurs as a stratocone on the northwestern tip of the Toba Caldera and belongs to the large Toba volcanic system, which has produced two super-eruptions in the Quaternary. Compositionally zoned olivine, plagioclase and clinopyroxene grains, together with orthopyroxene reaction rims around olivine from basalts and basaltic andesites of the Sipisupisu volcano indicate open-system processes characterized by multiple episodes of magma recharge and mixing. Based on compositional variations of a variety of zoned olivine and clinopyroxene crystals, melts ascended from the large basaltic magma reservoir at the Moho have resided in at least three staging magma reservoirs within the crust. One magma reservoir is Si-saturated and located < 13 km deep in the upper crust, underlain by two Si-undersaturated ones at a depth from ~ 13 to 25 km. Fe–Mg diffusion modeling shows that olivine residence time from mixing of compositionally more evolved magmas to eruption varies from ~ 7 days to 9 months, whereas that from recharge of more primitive magmas to eruption is ~ 6 months to 5 years. This timescale is, on average, longer than olivine residence time of the majority of mafic arc volcanoes worldwide and may favor prolonged crystal fractionation. The multiple staging magma reservoirs and prolonged crystal residence time of the Sipisupisu volcano could potentially be linked to the large basaltic magma reservoir at depth. Finally, mixing of Si-saturated and Si-undersaturated magmas probably triggered Sipisupisu eruption. [ABSTRACT FROM AUTHOR]

Agung, Bromo, and Sinabung Volcanoes have high volcanic activity over the last decade, and have different eruption characteristics. Hence, it would be fascinating to study the characteristics of their volcanic activity patterns based on SO2 emission rates and thermal anomaly correlated with the seismicity data. The SO2 emission rate measurement was carried out using the Differential Optical Absorption Spectroscopy (DOAS), and calculated based on SO2 column density, distance of measurement, wind speed, and wind direction. In addition, SO2 emission was detected using Ozone Monitoring Instrument (OMI) images with daily global coverage. Thermal anomaly detection was performed using Advance Spaceborne Thermal Emission and Reflection Radiometer (ASTER) of Thermal Infrared (TIR) subsystem with high spatial resolution (90x90 m). ASTER TIR images were corrected for radiometric and thermal atmospheric. The emissivity and brightness temperature separation algorithm was applied to obtain surface temperature of Agung, Bromo, and Sinabung Volcanoes. All the data were correlated with the seismicity of each volcano. The SO2 emission rates correlate with the magma ascent to the shallow depth in an open system volcano (Bromo Volcano). In the closed-system volcanoes (early phase of Agung and Sinabung), SO2 emission was detected after the transition of closed to open system. Magmatic injection from the reservoir to the shallow depth was detected as thermal anomalies, such as in Agung Volcano. Whereas in Bromo Volcano, the thermal anomaly was insignificant since Bromo Volcano has an explosive eruption at a short period, so the ASTER image could not observe the thermal anomaly on the eruption time. Thermal anomaly pattern in Sinabung Volcano was the manifestation of new magmatic injection to the shallow depth. Therefore, their increase serves as indicators for the increasing magmatic activity prior to the eruptions. [ABSTRACT FROM AUTHOR]

We studied Semeru, East Java, Indonesia, to show the population exposure to volcanic threats from its persistent, daily eruptive activity which endangers at least 50,000 of the 950,000 inhabitants living on the East, South and South-East slopes and ring plain. Surveys, mapping and statistical investigation enabled us to assess the extent of exposure of 145 neighbourhoods (termed blocks) and characterize hazards and response to eruptions in 15 rural villages and small towns. Statistical analyses of datasets of 23 variables (11 of exposure, 7 of hazards, and 5 of response) and their attributes involved three operations: 1. Univariate and bivariate analyses enabled us to explore data and characterize the relationships between 11 variables to compute a multi-component exposure index. 2. Polytomous Logistic Regression (PLR) models selected six optimal exposure variables, suggesting that logistic regression can predict the exposure index for blocks outside the survey area and potentially on any active volcano. 3. Multivariate analyses and Hierarchical Agglomerative Clustering (HAC) distinguished four groups of blocks based on attributes of all variables correlated with the exposure index score. To contribute to disaster risk reduction, the distance/time criterion was applied to access ways and response facilities to highlight remote or blocked blocks in danger of imminent eruption including evacuation. Statistical analysis of optimal variables from local scale surveys can help identify neighbourhoods where disaster risk mitigation requires improvement. [ABSTRACT FROM AUTHOR]

Suspension flow into the upstream of volcano watershed is sensitive to land use. In Indonesia, a settlement is a form of land use in several volcanic landscapes. There is currently no detailed study on the suspension flow sediment from the settlement land use. The purpose of this study is to investigate the characteristics of the relationship between water and suspension flow discharge. The study was conducted through the measurements at a gully outlet that produced 747 suspension load data. For each rainfall event, suspension load measurements were made in the field, followed by laboratory analysis. Additionally, field surveys were used to determine the characteristics of settlement land use and the water flow into the gully system. According to the findings, the peak flow discharge corresponds to the peak suspension discharge, the peak flow discharge comes before the peak suspension discharge, and the peak flow discharge happens after the peak suspension discharge. The average time lag between initial rainfall events and suspension flow was 10.36 minutes, and the suspension peak content varied by an average of 2.22 gl-1. The grain size was also dominated by the clay fraction, averaging 67.86% on the ascending branch and 67.82% on the descending branch. [ABSTRACT FROM AUTHOR]

The magma evolution of Ngebel Volcano, both temporally and spatially, is represented by the characteristics of its lava. Ngebel Volcano, located in East Java, is a Quaternary andesitic stratovolcano. This volcano is part of the Wilis Volcanic Complex. The volcanism stage of Ngebel Volcanic Complex can be divided into the Jeding with andesitic basalt (SiO2 49 - 59%), pyroxene andesite Kemlandingan (SiO2 49 - 59%), Manyutan with hornblende andesite (SiO2 49 - 59%), and Ngebel with dacite (SiO2: 49 - 59%). The variation of major elements combined with petrographic features such as plagioclase, pyroxene, hornblende, quartz, and opaque minerals from basaltic andesite to dacite is interesting. The minerals show that the magma differentiation process of Ngebel Volcanic Complex is the results of fractional crystallization of magma. The purpose of this study is to determine the evolution of magma from volcanic rocks of which stratigraphic positions have been determined. The analytical methodology used is petrographic and geochemical analysis. Detailed temporal evolution shows that magma from the Ngebel Volcanic Complex underwent a differentiation process that changed the magma composition from mafic to more felsic. [ABSTRACT FROM AUTHOR]

New Sr isotope and K2O data are presented for Papandayan and Cikuray Volcanoes in West Java. The data are combined with published Sr isotope and K2O data, and compared with arc that has a similar geological setting, namely Northeast Japan Arc (NJA, N 38° ~ 41°) to constrain the relative importance of crustal assimilation and subducted input of crustal material in magma genesis beneath West Java Arc (WJA). New strontium isotope and K2O data from fifty-four Quaternary volcanic rocks from WJA were collected and compared to forty-six Quaternary volcanic rocks from NJA. The increasing K2O and decreasing of 87Sr/86Sr ratios with distance from trench have been found in NJA, but there are rough and no across arc variation of K2O and Sr isotopic ratios in WJA. This study shows that the across arc variation of magma chemistry on the WJA is attributed to the crustal assimilation and the involvement of subducted sediments and slab fluids from altered oceanic crust. [ABSTRACT FROM AUTHOR]

Volcano flank collapses have been documented at ocean islands worldwide and are capable of triggering devastating tsunamis, but little is known about the precursory processes and deformation changes prior to flank failure. This makes the 22 December 2018 flank collapse at Anak Krakatau in Indonesia a key event in geosciences. Here, we provide direct insight into the precursory processes of the final collapse. We analyzed interferometric synthetic aperture radar (InSAR) data from 2014 to 2018 and studied the link between the deformation trend and intrusion occurrence through analogue modeling. We found that the flank was already moving at least 4 yr prior to collapse, consistent with slow décollement slip. Movement rates averaged ~27 cm/yr, but they underwent two accelerations coinciding with distinct intrusion events in January/February 2017 and in June 2018. Analogue models suggest that these accelerations occurred by (re)activation of a décollement fault linked to a short episode of magma intrusion. During intrusion, we observed a change in the internal faults, where the outward-directed décollement accelerated while inward faults became partially blocked. These observations suggest that unstable oceanic flanks do not disintegrate abruptly, but their collapse is preceded by observable deformations that can be accelerated by new intrusions. [ABSTRACT FROM AUTHOR]

A study of volcanic hazard knowledge and preparedness of communities living on the flanks of Gamalama Volcano, on the small island Ternate, was conducted in January–February 2019. A total of 1265 respondents participated in a questionnaire-based survey using 42 questions to inquire about community knowledge of natural disasters and volcanic hazards, community preparedness, and the correlation between community knowledge and preparedness. The results showed that the majority of respondents selected from the small island community had good knowledge of natural disasters and volcanic hazards and were also well-prepared. There are positive correlations between knowledge of natural disasters and volcanic hazards; the latter is also positively linked to preparedness. Long experience in dealing with the eruptions of Gamalama in the past has raised local people's awareness of volcanic hazards, which in turn increases their preparedness. Such understanding and preparedness are inseparable from the abundant dissemination channels of details on eruption threats and risks on Ternate Island, including televisions, the internet, radios, government officials, and non-governmental organizations. [ABSTRACT FROM AUTHOR]

Volcanic eruptions from Gamalama volcano often threaten Ternate Island, a small volcanic island with more than 200,000 inhabitants in North Maluku Province. Ternate Island has an area of 111.4 km2, and the distance between settlements and the crater ranges from 4-7 km. With those conditions, Ternate Island has become one of the areas in Indonesia with a high risk of volcanic hazards. As one of the efforts to reduce volcanic risk, it is essential to understand the characteristics of volcanoes, including the relationship between the repose period and the eruption magnitude. Historical data on the eruption of the Gamalama volcano from 1510-2018 were collected from various reliable sources and analyzed statistically to determine their relationship. The results show no significant relationship between the repose period and the magnitude of the eruption. The results also show that the eruption's average repose time from 1510-2018 is unreliable and cannot be generalized. However, one thing that is quite interesting to be studied further is related to the positive relationship between the length of the repose period and the impact of the resulting eruption. This incident was recorded in several eruptions at Gamalama volcano, such as in 1960, 1980, 2003, and 2011. These findings require people living on Ternate Island to increase their preparedness and practice in dealing with eruption disasters following the contingency plan from the disaster management authority. [ABSTRACT FROM AUTHOR]

Copyright of Rudarsko-Geolosko-Naftni Zbornik is the property of Faculty of Mining, Geology & Petroleum Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Volcano tourism is a part of ecotourism or geotourism in developed and developing countries. The visitors or tourists in this kind of tourism immerse themselves in the bodily enjoyment of feeling and sensing the volcano's high elevation instead of viewing its beauty. The present article aims to explore tourists' subjective experiences of being at a high altitude by taking the case of Mount Semeru tourists. The tourist attraction of Mount Semeru as a volcanic mountain has a selling point and appeal for climbing but with threats and risks. This research explores and reveals the meaning of hiking trips and the manifestation of fear during trips in risky areas. The existential-phenomenological approach examines multifaceted phenomena from an individual's point of view. Informants were determined by using a purposive sampling technique. In this phenomenological study, researchers look for information (individuals) who have the capability so they can articulate their life experiences related to the phenomenon under study. This study's results describe the experience of climbers enjoying the journey through struggles and successes by interpreting the phenomena during the ascent and the anticipatory attitude of climbers toward facing the threats and risks of climbing Mount Semeru. [ABSTRACT FROM AUTHOR]

Spatial approaches, based on the deformation measurement of volcanic domes and crater rims, is key in evaluating the activity of a volcano, such as Merapi Volcano, where associated disaster risk regularly takes lives. Within this framework, this study aims to detect localized topographic change in the summit area that has occurred concomitantly with the dome growth and explosion reported. The methodology was focused on two sets of data, one LiDAR-based dataset from 2012 and one UAV dataset from 2014. The results show that during the period 2012–2014, the crater walls were 100–120 m above the crater floor at its maximum (from the north to the east–southeast sector), while the west and north sectors present a topographic range of 40–80 m. During the period 2012–2014, the evolution of the crater rim around the dome was generally stable (no large collapse). The opening of a new vent on the surface of the dome has displaced an equivalent volume of 2.04 × 104 m3, corresponding to a maximum −9 m (+/−0.9 m) vertically. The exploded material has partly fallen within the crater, increasing the accumulated loose material while leaving "hollows" where the vents are located, although the potential presence of debris inside these vents made it difficult to determine the exact size of these openings. Despite a measure of the error from the two DEMs, adding a previously published dataset shows further discrepancies, suggesting that there is also a technical need to develop point-cloud technologies for active volcanic craters. [ABSTRACT FROM AUTHOR]

On 15 January 2022, a VEI 5 eruption occurred at the submarine Hunga Tonga-Hunga Ha'apai (HTHH) Volcano in the Southwest Pacific, causing an ash plume reaching a height of 50–55 km. The eruption generated strong acoustic-gravity waves in the near-field and stations all over the world recorded Lamb waves (LW) that travelled around the earth multiple times at a speed of ~0.3 km/s. Here we report ionospheric anomalies due to the LW over Indonesian islands, 5000–10,000 km away from the volcano, in terms of changes in total electron contents (TEC) using the nationwide network of GNSS stations. We detected ionospheric anomalies travelling above Indonesia several times both westward and eastward. The first passage of LW over Java caused strong TEC increases of >12 TECU. The wave circled the earth and returned to Java on subsequent days. The second passage was recorded early 1/17, the anomaly decayed to 6 TECU. We also detected the passage of long-path waves propagating from west to east. In addition to such anomalies, we examined the existence of ionospheric disturbances apparently propagating from the geomagnetic conjugate point of the volcano that could possibly emerge in Indonesia. However, their signatures in Indonesia were not clear. [ABSTRACT FROM AUTHOR]

This article calls attention to problematic effects of the so-called "ontological turn" that now gains ground in academic anthropology, especially the entailments of perspectival multi-naturalism. I argue that a consistent embrace of this approach challenges public anthropology at its core. The irrealist grounding of perspectival multi-naturalism encourages withdrawal from both analysis and engagement, rendering the application of anthropological knowledge dubious. In order to counter this development, I suggest a reorientation in terms of realist principles, notably those of Roy Bhaskar's critical realism. The diverging theoretical and ethical implications of these approaches are exemplified through a discussion of threats to health and life in Java, Indonesia. [ABSTRACT FROM AUTHOR]

Indonesia hosts the largest number of active volcanoes, several of which are renowned for climate-changing historical eruptions. This pedigree might suggest a substantial fraction of global volcanic sulfur emissions from Indonesia and are intrinsically driven by sulfur-rich magmas. However, a paucity of observations has hampered evaluation of these points—many volcanoes have hitherto not been subject to emissions measurements. Here we report new gas measurements from Indonesian volcanoes. The combined SO2 output amounts to 1.15 ± 0.48 Tg/yr. We estimate an additional time-averaged SO2 yield of 0.12-0.54 Tg/yr for explosive eruptions, indicating a total SO2 inventory of 1.27-1.69 Tg/yr for Indonesian. This is comparatively modest—individual volcanoes such as Etna have sustained higher fluxes. To understand this paradox, we compare the geodynamic, petrologic, magma dynamical and shallow magmatic-hydrothermal processes that influence the sulfur transfer to the atmosphere. Results reinforce the idea that sulfur-rich eruptions reflect long-term accumulation of volatiles in the reservoirs. Indonesia is the country with the most active volcanoes, several of which are renowned for climate-changing eruptions. Here the authors show a rather moderate sulfur emissions budget and reinforce the idea that sulfur-rich eruptions reflect long-term accumulation of volatiles in the reservoirs. [ABSTRACT FROM AUTHOR]

Gaseous emissions and particulate matter in different aerodynamic diameters can be derived from many sources, such as volcanic activities. According to previous studies, gaseous emissions, such as sulfur dioxide, carbon monoxide, and carbon dioxide, may affect human health. Furthermore, there is a significant correlation between exposure to gaseous emissions and cell deformation, indicating the organ system's abnormalities. Therefore, there is a need to mitigate and identify volcanic gaseous emissions as an identification system. Thus, this study conducted an in situ volcanic gaseous emissions concentration measurement system collected directly from areas near the plume of Welirang volcano, Malang, East Java Province, Indonesia (7o 43'59" S 112o 34'29" E). The measurement system consisted of several gases and particulate matter sensors. The measurements were conducted on ten areas surrounding the Welirang volcano's plume to identify the highest volcanic emission dispersion. The emission concentrations were measured for five minutes every 30 seconds as the interval time. The results show that emission consisted of several gases and particulate matters in different concentrations, such as carbon monoxide, carbon dioxide, methane, and toluene. In addition, the concentrations were influenced by the distance of the measurement sites to the plume. Therefore, the system works well with a response time of fewer than two seconds and the sensitivity of 0.56 Volt/ppm and 0.63 Volt/ppm, respectively, for methane and toluene. The range of the system measurement is 0-100 ppm (carbon monoxide), 400-1,000 ppm (carbon dioxide), 0-100 ppm (methane), and 0-100 ppm (toluene). [ABSTRACT FROM AUTHOR]

Sinabung volcano in Indonesia reactivated, with a series of phreatic eruptions, in August and September 2010. These eruptions were followed by various types of magmatic eruption at the summit, including lava dome growth, pyroclastic density currents, lava flow, and vulcanian eruptions, starting in December 2013. Prior to the magmatic eruptions, Sinabung exhibited two sequences of phreatic eruption and an increase in the seismicity of volcanic earthquakes. This study clarifies the progress of magma intrusion during the pre-magmatic period based on the hypocenter distribution, waveform similarity, seismic moment, rupture length, and stress drop for volcano-tectonic (VT) and hybrid earthquakes. It was found that the hypocenters of VT earthquakes are distributed north and northwest of the summit at a depth range of 1–10 km below sea level. Deep seismicity (4–10 km) alternated with shallow seismicity (2–4 km). The last shallow seismicity, from July to mid-December 2013, was different from previous seismicity in terms of higher intensity, as determined from the seismic moment, a temporary increase in the rupture length, and the migration of hypocenters towards the summit. The seismicity of VT earthquakes was altered by a swarm of hybrid earthquakes in mid-December. The hybrid earthquakes were smaller, in terms of seismic moment (mostly <3 × 1010 Nm), than the VT earthquakes. Their hypocenters were concentrated in the shallowest depth range (−0.5 to 1.5 km below sea level) directly below the summit, their source process was repeatable (they could be grouped into six earthquake families), their dominant peak was in a low-frequency range (2.5–4.5 Hz), and they had a relatively low stress drop (<0.15 MPa). This suggests that the swarm of hybrid earthquakes was induced by a frequent repeated fracture of fluid-filled cracks due to the intrusion of magma up to directly below the summit. The transition of the earthquake family and the change in its source parameters, namely an increase in the stress drop prior to the appearance of a lava dome and then a slight decrease, may reflect a gradual change in internal pressure in the hypocentral zone through the magma intrusion process. • Detailed the magmatic intrusion process before the Sinabung magmatic eruption. • Temporal changes of source parameters of VT and hybrid earthquakes • The transition of the hybrid earthquake family and the change in its source parameters • A temporary increase in the rupture length of VT earthquakes indicates new magma intrusions. [ABSTRACT FROM AUTHOR]

Bromo is among the very active volcanoes in Indonesia and is known for its recurrent and long-lasting eruptive manifestations. Past volcanic gas studies have revealed Bromo as one of the principal sources of volcanic degassing in Indonesia. This high degassing from Bromo volcano is further characterized in this work, based on more than 10 years of intermittent ground-based gas measurements, combined with daily SO2 mass, captured by the OMI sensor. Over the past decade, Bromo has released 0.7 Tg of SO2 into the atmosphere, representing 3% of the volcanic degassing budget of Indonesia and 0.3% of the global volcanic SO2 emission budget outside eruptive periods. Results also reveal that 18.8 Tg of H2O, 2.0 Tg of CO2, 0.1 Tg of H2S, and 0.005 Tg of H2 were released from the Bromo volcano in one decade. About 81% of these gases are released passively between eruptive events. The chemistry of the eruptive products, sampled between 2001 and 2019, indicate that Bromo volcanic activity is sustained by a basaltic-andesite to basalt trachy-andesite magma source with a transition from medium-K to high-K composition. Such an evolution associated to a C-rich gas likely resulted from a low partial melting and sediment contribution to the genesis of the source magma. New magma injections into the reservoir and fractional crystallization have further amplified the changes of magma composition. Finally, we speculate that the shallow reservoir replenishment, in response to the continuous strong degassing is the driving mechanism behind the Bromo frequent eruptive events. [ABSTRACT FROM AUTHOR]

On 22 December 2018, volcano Anak Krakatau, located in Indonesia, erupted and experienced a major lateral collapse. The triggered tsunami killed at least 437 people by the 13-m-high tide. Traditional optical imagery plays a great role in monitoring volcanic activities, but it is susceptible to cloud and fog interference and has low temporal resolution. Synthetic aperture radar (SAR) imagery can monitor volcanic activities at a high temporal resolution, and it is immune to the influence of clouds. In this paper, we propose an automatic method to accurately extract the volcano boundary from SAR images by combining multi-polarized water enhancement and the Nobuyuki Otsu (OTSU) method. We extract the area change of the volcano in 2018–2019 from Sentinel-1 images and ALOS-2 imagesThe area change and evolution are verified and analyzed by combing the results from SAR and optical data. The results show that the southeastern part of the volcano expanded significantly after the eruption, and the western part experienced collapse and recovery. The volcano morphology change experienced a slow-fast-slow process in the two years. [ABSTRACT FROM AUTHOR]

The area surrounding Jaboi volcano, Indonesia, has been planned for geothermal energy development with capacity of ~ 50 Mwe. Geophysical surveys can contribute to the understanding of the hydrogeology of the area because they can provide information without interferences, which could potentially react to the flow of hot water. In many cases, the occurrence of a hot spring is closely related to its local fault system, which permits the flow of thermal fluid to its surface. This research applied the very low-frequency electromagnetic (VLF–EM) method and then compared it with electrical resistivity data to map fractures, faults, and geological aspects in the Jaboi volcano manifestation area. In tropical areas such as Indonesia, the VLF–EM method has been applied widely in studying subsurface structures. However, it is rarely used in volcanic areas with high terrain conditions even though the mobility of VLF methods is simpler than the electrical resistivity method. At the west side of the volcano, the 2D models from both VLF–EM and electrical resistivity showed the conductive zone (log 0.5–1.5 Ωm) found as a response to the manifestation, which has a similar direction with a local fault known as the Ceuneuhot fault. At the east side, the 2D models from both methods showed a similar conductive zone at depths of 15–25 m, which is caused by the existence of bedrock (> log 2.5 Ωm). The bedrock at depths of 0–10 m inhibits the rise of fluid to the surface so that there is no geothermal manifestation in the other local fault known as the Leumomate fault. In addition, the 2D models from the two methods showed the contrast of some fracture zones as entry and exit points of fluid in the Jaboi volcano. In addition, analysis of Landsat 8 optical images also showed high-temperature values and low vegetation indices in several active craters as indicators of volcanic activity. Based on the processed data, it is concluded that VLF–EM can be used as a fast and accurate method to provide information about near-surface structures in a geothermal field, and it can be used safely to suggest a location for drilling programs or to give contributions to protect geothermal springs. [ABSTRACT FROM AUTHOR]

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Research on rock layer contact at Sutami Dam, Karangkates Village, Sumberpucung District, Malang Regency, Indonesia was undertaken. This research was conducted to identify volcanic sediments layers' which contact with Limestone Sediments in the surrounding of Sutami Dam and to mitigate potential disasters in the dam's surrounding area. This research was conducted by a geomagnetic method. Data were collected using the Proton Precession Magnetometer G-856. The geomagnetic data acquisition started from the Kromengan District (112.494oE; 8.129oS) to the Sukorame District (112.358oE; 8.213oS). The radius of geomagnetic data acquisition was 15 km; the space between the points was 300 meters with 1372 measurement points. The value of the geomagnetic intensity are between -210 nT to 514 nT. The northern part of the research location has a lower total geomagnetic intensity than the southern area. The northern part is thought to be volcanic sediment (Tuff Desposits and Butak Volcanic Sediments), which only covers the surface, while the southern part is (Limestone Sediments) Marine sediment, which is some parts thought to have been volcanoes in ancient times. The ancient volcanoes in the southern part are Mounts Golo, Selorejo, Selumban, Tretes, Soko, Pehlembun and Krowedul. The contact layer between volcanic sediments with Limestone Sediments is more difficult to consolidate, so that the buildings built on them are more vulnerable. [ABSTRACT FROM AUTHOR]

Magma volatile budgets and storage depths play a key role in controlling the eruptive styles of volcanoes. Volatile concentrations in the melt can be inferred from analyses of glass inclusions, which however may not be present in the investigated rocks or may have experienced post-entrapment processes that modify their volatile records. Apatite is becoming an alternative robust tool for unraveling the information of magmatic volatiles. Here we report a comprehensive dataset for the concentrations of volatiles and major elements in apatite crystals in the rocks from two eruptions with contrasting eruptive styles: the 2006 (dome-forming) and 2010 (explosive) eruptive events at Merapi volcano (Java, Indonesia). We obtained two-dimensional compositional distributions and in situ concentrations of H2O, CO2, F, Cl and S in 50 apatite crystals occurring at various textural positions. The CO2 concentrations we report are probably the first ones from natural volcanic apatite. Using the volatile concentrations in apatite and existing thermodynamic models and geothermobarometers, we have calculated the volatile abundances of the pre-eruptive melts of the two eruptions. We find that the apatite from the 2006 and 2010 deposits have a similar compositional range of volatiles, with a bimodal distribution of F–H2O–CO2 contents. The apatite included in amphibole has higher H2O (0·9–1·0 wt %) and CO2 (⁠ ≥ 2400 ppm), but lower F (0·9–1·4 wt %), compared to crystals included in plagioclase, clinopyroxene, or in the groundmass (H2O: 0·4–0·7 wt %; CO2: 40–900 ppm; F: 1·7–2·3 wt %). Using these volatile concentrations and apatite-melt exchange coefficients we obtained two distinct ranges of H2O–CO2–S–F–Cl concentrations in the melt. Melts in equilibrium with apatite included in amphibole had 3–8 wt % H2O, ≥8000 ppm CO2, 340–2000 ppm S, whereas melts in equilibrium with apatite included in anhydrous minerals and in the groundmass had lower H2O (1·5–4 wt %), CO2 (60–2500 ppm), and S (10–130 ppm). We calculated the melt H2O–CO2 saturation pressures and found that they correspond to two main magma storage depths. The shallow reservoir with melts stored at ≤10 km below the crater agrees with the depths constrained by melt inclusions, as well as the geodetic, geophysical and seismic tomography studies from the literature. We have also found a significantly deeper melt storage zone at ≥25–30 km recorded by the C- and H2O-rich apatite in amphibole and barometry calculations using amphibole and high-Al clinopyroxene, which matches with the depths reported in seismic tomography studies. The high CO2/H2O and CO2/SO2 concentrations of the deep melt can help to explain the sharp increase in these ratios in fumarolic gas that were sampled just before the eruption in 2010. Supply of deep volatiles to the shallower magma column before the eruption in 2010 could have increased the magma buoyancy, and thus led to higher magma ascent rates and associated eruption explosivity. Evidence for the faster pre-eruptive magma ascent in 2010 than 2006 is also found on the diffusion distance of Cl in apatite microlites. [ABSTRACT FROM AUTHOR]

Volcanoes are surrounded by villages, towns, and polities that are constantly shifting location to benefit from the rich soils generated in the aftermath of eruptions, while, at the same time, avoiding the worst of their destructive potential. We explore the attraction of volcanoes in a Southeast Asian context through a comparative examination of the communities surrounding Mount Mayon in the Bicol peninsula of the Philippines and Gunung Awu on the island of Sangihe Besar in Indonesia. These volcanoes influence the location of settlements, forms of community identity, and the expression of cultural memories. We argue that risk awareness programmes that disregard the extent to which a volcano is embedded within the physical and mental fabric of a society and fail to connect to local historical cultural memory are likely to have little lasting effect on reducing people's vulnerability. [ABSTRACT FROM AUTHOR]

Mt. Seulawah Agam could make a good location for a geothermal power plant with an estimated energy of 150 Mwe. In geothermal exploration, thermal and multispectral imagery is required for surface temperature calculation, subsurface temperature modeling, and mapping of geothermal potential in volcanoes. In general, temperature data and vegetation index are obtained through such satellite images as Landsat, MODIS, and Sentinel. However, satellite images cannot be used for a small area due to the low resolution (> 15 m/px). In this study, the researchers used a small DJI Phantom 4 Quadcopter equipped with the FLIR One and MAPIR Survey 3 sensors to map the heat signatures of a geothermal feature from the Ie Jue geothermal manifestation, Seulawah Agam, Indonesia. An area of 500 m x 430 m has been scanned, and the images were mosaicked and processed using Drone Deploy Cloud and ArcGIS 10.2. Based on the data processing, NDVI data calculated from the MAPIR sensor are capable of showing vegetation contrast with high resolution (5 cm/px) in several manifestations, which also correspond to Landsat-8 imagery. Meanwhile, the FLIR thermal sensor shows a temperature of 85 °C in the manifestation area, which was confirmed by a geo-thermometer and field outcrops. It was proved that, compared to satellite imagery, UAVs could be applied effectively to support the quantitative assessment of geothermal resources in volcanoes. [ABSTRACT FROM AUTHOR]

The 22 December 2018 Anak Karakatau tsunami in Indonesia was a rare event in that few instrumental records existed of tsunamis generated by volcanic sources before this event. The tsunami, which left a death toll of 437, is of global importance as it provides opportunities to develop knowledge on generation, propagation and coastal effects of volcanic tsunamis. Here, we report results of field surveys along the coast of the Sunda Strait, Indonesia to study tsunami wave heights and coastal damage. We surveyed 29 locations and measured ranges of tsunami runup from 0.9 to 5.2 m, tsunami heights from 1.4 to 6.3 m, flow depths from 0.2 m to 3.0 m and inundation distances from 18 to 212 m. The largest tsunami heights and concentration of damage and fatalities occurred on the western shore of Java from Tanjung Lesung to Sumur. The largest cluster of fatalities occurred at Tanjung Lesung, where more than 50 people died while attending an outdoor music being held at the shoreline. The tsunami runup and tsunami height in Tanjung Lesung were 4.0 and 2.9–3.8 m, respectively. We believe this tragedy could have been avoided if the event organizers were more aware of the hazard posed by the Anak Krakatau volcano, as it had been actively erupting for several months prior to the tsunami, and simply moved the concert stage 100 m inland. Many of the locations surveyed demonstrated a similar pattern where the majority of casualties and destruction occurred within 100 m of the coast; in several locations, lives were saved where buildings were located at least this distance inland. The significant damage and numerous deaths which occurred in Sumur, despite the moderate tsunami height of 2.3–2.5 m, can be attributed to the extremely low-lying coastal land there. Flow depth in Sumur was 0.9–2.0 m. During our field surveys, nearly one year after the event, we noted that some of the damaged buildings were being rebuilt in the same locations just 10–30 m from the shoreline. We question this practice since the new buildings could be at the same tsunami risk as those damaged in the 2018 event. [ABSTRACT FROM AUTHOR]

Motivated by the unwarned tsunami disaster caused by the flank collapse of the Anak Krakatau volcano on 22 December 2018, we used a landslide tsunami model to explore potential tsunami observing and warning systems for the region. With the estimated volume of 0.24 km3 and the relatively short duration (~3 to 5 min), the landslide of the volcanic edifice in the southwest sector triggered a tsunami of higher than 40 m in the vicinity. The tsunami, however, attenuated rapidly as it propagated away from the generation area, resulting in lower than 2 m wave heights at tide gauges around the Sunda Strait. Using the tsunami model, we demonstrated the capability of a ship height positioning method to detect the tsunami of amplitude ~20 cm associated with the event. Furthermore, assimilating the tsunami current velocity observed by high‐frequency oceanographic radars can produce accurate forecasts of coastal tsunami heights. Plain Language Summary: The tsunami on 22 December 2018 claimed hundreds of lives across the Sunda Strait regions of Indonesia. Unlike typical tsunamis, this silent tsunami was caused by the activity of Anak Krakatau volcano. This paper proposes new tsunami observation and warning systems for such a tsunami by modeling the generation and propagation processes. Although the source characteristics are constrained using limited data, that is, satellite images, the model can reproduce tsunami waveforms recorded at tide gauges and flow depths measured at specified regions. We then perform numerical experiments to assess the performance of potential tsunami observing systems based on high‐frequency oceanographic radars and ship‐height positioning. The experiment suggests that both systems can be viable future tsunami observations in the region. Key Points: The study models the tsunami generation and propagation processes associated with the Anak Krakatau volcanoWe validate our model against tsunami waveforms at tide gauges and flow depthsBased on the model, tsunami observing systems using oceanographic radars and ship height positioning are suitable for the region [ABSTRACT FROM AUTHOR]

On December 22, 2018, a sector of the Anak Krakatau volcano edifice collapsed into the sea, generating a tsunami that hit the Sunda Strait coasts in Indonesia. The collapse followed a period of 6 months of volcanic activity that was insufficient to warn the tsunami-threatened coastal population. The Anak Krakatau tsunami resulted in hundreds of casualties, thousands of injured and displaced people, and massive coastal damage. This paper uses the tsunami records, the collected field survey data, and satellite imagery-based interpretations to develop a model of the Anak Krakatau flank failure and tsunami. We address the dynamics of the flank failure, the tsunami generation and propagation, and the coastal impact using evidence-calibrated numerical modelling. An in-house-developed multi-layer viscoplastic shallow-water numerical code is employed to simulate the Anak Krakatau collapse mass movement and the whole source-to-coast tsunami process. Our results suggest that a flank collapse scenario involving a volume of material of 0.135 km3 and occurring as a sequence of two failures fairly reproduces the local and regional tsunami records and survey data. [ABSTRACT FROM AUTHOR]

In August 2010, Sinabung volcano began erupting after more than a thousand years of dormancy. Following several weeks of phreatic eruptions, the eruptions ceased and Sinabung entered what became an inter-eruptive period of dominantly seismic unrest. While standard equations for understanding the size of an earthquake (local magnitude (ML), coda magnitude (MC), and seismic energy release (ER)) have long been developed, it is best practice to fine tune these relations for a given region and period of study to more accurately describe seismicity and to directly compare it with other volcanic systems. More accurate descriptions of magnitudes and energy release are vital to accurate volcanic eruption forecasting and evaluation of seismic and volcanic risk. In this study, we use high-frequency volcano-tectonic (VT) earthquakes recorded on a temporary three-component network installed between October 2010 and December 2011 in the region around Sinabung volcano to better constrain the seismic parameters of and better understand this previously unstudied volcano. We determine region-specific formulas for ML, MC, and ER as follows: M L = log 10 A + 1.1252 log 10 r + 0.0280 r − 2.5427 , M C = 0.7764 log 10 t coda + 0.0676 r − 0.7185 , and log 10 E R = 1.5720 M L + 11.5258 , where A, r, and tcoda are maximum amplitude on a Wood-Anderson seismogram, hypocentral distance (km), and the coda duration (s), respectively. Constants in the ML equation have physically interpretable meanings. The constant for the geometrical spreading term (log10r term) equals one for perfect spherical spreading of the waveform. Our value is greater than one and thus suggests that wavefronts spread at a slightly different rate than for simple spherical spreading. The constant for the attenuation term (r term) is consistent with locally mapped attenuative deposits (limestones and tuffs) and previous 3D tomographic results. Our MC equation differs from a previous study, likely because different data in a different time period were used. Earthquake hypocenters are consistent with those located in previous tomographic studies, and we interpret the earthquakes in this study as distal VT earthquakes induced by continued magmatic intrusion at Sinabung over the period of October 2010–December 2011. [ABSTRACT FROM AUTHOR]

Comprehending the characteristics of infiltration is essential for conserving spring recharge areas, particularly on hillslopes of a Quaternary volcanic landscape. Quantitative investigations were carried out to identify soil physical properties and morphological features related to infiltration behavior. We used 15 transects with 70 sampling points in total to collect soil samples, observed morphological characteristics, and measured the infiltration. Data analysis employed statistical methods, including principal component analysis (PCA) and K-means cluster analysis. PCA revealed that infiltration was strongly correlated with slope, slope length, surface curvature, and slope position and that it was a function of soil physical properties, i.e., soil moisture, particle size distribution, and bulk density. The K-means cluster analysis classified the sampling points into four clusters that corresponded to three slope positions, namely upper slope, middle slope, and footslope. The high infiltration rate in the middle slope was caused by the relatively steep slope, sandy soil texture, low soil moisture, and low bulk density. On the contrary, the relatively flat slope, high clay content, high soil moisture, and high bulk density of the footslope created a low infiltration rate. According to these infiltration parameters, the preferred area for spring water catchment conservation was the middle slope. [ABSTRACT FROM AUTHOR]