Eruption Research Articles

Excitation of ULF, ELF, and VLF Resonator and Waveguide Oscillations in the Earth–Atmosphere–Ionosphere System by Lightning Current Sources Connected with Hunga Tonga Volcano Eruption

The simulations presented here are based on the observational data of lightning electric currents associated with the eruption of the Hunga Tonga volcano in January 2022. The response of the lithosphere (Earth)–atmosphere–ionosphere–magnetosphere system to unprecedented lightning currents is theoretically investigated at low frequencies, including ultra low frequency (ULF), extremely low frequency (ELF), and very low frequency (VLF) ranges. The electric current source due to lightning near the location of the Hunga Tonga volcano eruption has a wide-band frequency spectrum determined in this paper based on a data-driven approach. The spectrum is monotonous in the VLF range but has many significant details at the lower frequencies (ULF, ELF). The decreasing amplitude tendency is maintained at frequencies exceeding 0.1 Hz. The density of effective lightning current in the ULF range reaches the value of the order of 10−7 A/m2. A combined dynamic/quasi-stationary method has been developed to simulate ULF penetration through the lithosphere (Earth)–atmosphere–ionosphere–magnetosphere system. This method is suitable for the ULF range down to 10−4 Hz. The electromagnetic field is determined from the dynamics in the ionosphere and from a quasi-stationary approach in the atmosphere, considering not only the electric component but also the magnetic one. An analytical/numerical method has been developed to investigate the excitation of the global Schumann resonator and the eigenmodes of the coupled Schumann and ionospheric Alfvén resonators in the ELF range and the eigenmodes of the Earth–ionosphere waveguide in the VLF range. A complex dispersion equation for the corresponding disturbances is derived. It is shown that oscillations at the first resonance frequency in the Schumann resonator can simultaneously cause noticeable excitation of the local ionospheric Alfvén resonator, whose parameters depend on the angle between the geomagnetic field and the vertical direction. VLF propagation is possible over distances of 3000–10,000 km in the waveguide Earth–ionosphere. The results of simulations are compared with the published experimental data.

Geomorphic time series reveals the constructive and destructive history of Havre caldera volcano, Kermadec arc

Monitoring active seafloor processes requires repeated, comparable surveys to enable change detection. The change detection of the deep ocean floor, however, is rare due to a paucity of repeat data at an appropriate resolution. In this study, we use an exceptional suite of bathymetric surveys across a spatiotemporal range at the submarine Havre volcano, Kermadec arc, Southwest Pacific, to investigate geomorphic change over 13 years (2002, 2012, and 2015). The integration of bathymetric observations with remotely operated vehicle (ROV) observations and sampling data refined geomorphic boundaries, and four geomorphic groups at varying scales are interpreted: (i) large-scale tectonic and volcanic features, e.g., faults and calderas; (ii) coherent volcanic products, e.g., lavas; (iii) clastic primary volcanic products, e.g., giant pumice deposits; and (iv) mass-wasting features and products, e.g., landslide scarps. Three 25-m resolution geomorphic maps for broad-scale feature change and high-resolution 1-m autonomous underwater vehicle (AUV) bathymetry are used to develop a fine-scale geomorphic map that reveals additional landforms and processes. We integrate bathymetric data with sampling data and ROV video footage of the seafloor to refine geomorphic boundaries. We also integrate the results of previous geological studies of Havre to inform the geomorphic interpretation. Our map reveals a variety of geomorphic forms from a range of volcanic and mass-wasting processes that aid in the interpretation of the growth and evolution of submarine volcanoes. One new observation reveals a significantly larger scale of cryptodome emplacement than recognized previously recognized, accounting for an additional volume of 0.0055 km3 to the 2012 eruption products. This emplacement took place along two linear southern caldera ring faults and likely continued after the formation of the giant pumice raft on 18 July 2012. A key result is the extension of the timeline for the emplacement of volcanic products associated with the 2012 eruption, revealing an additional volume growth of 0.001 km3 on the primary dome (dome OP) between 2012 and 2015. This additional emplacement is documented in this study for the first time and extends the known volcanic emplacement timeline from 3 months to a maximum of 3 years. Our work reveals seafloor modification continuing long after an observed volcanic eruption event as lingering lava emplacement and mass wasting remobilize newly erupted and older products that comprise the edifice.

Magma composition drives tremors during a volcanic eruption

Magma composition drives tremors during a volcanic eruption

Utilizing Remote Sensing and GIS to Study Natural Disasters "Volcanoes" and Their Impact on Climate Change

Multifarious regions around the world are exposed to natural hazards and disasters, each with unique characteristics. A higher frequency of extreme hydro-meteorological events, most probably related to climate change, and an increase in vulnerable population have been addressed as potential causes of such disasters. To mitigate the consequences of these disasters, Disaster Risk Management, including hazard assessment, elements-at-risk mapping, vulnerability and risk assessment of spatial components as well as Earth Observation (EO) products and Geographic Information Systems (GIS), should be considered. Multihazard assessment entails the evaluation of relationships between various hazards, including interconnected or cascading events, as well as focusing on various levels from global to local community levels, as each level manifests particular objectives and spatial data. This paper presents an overview of the diverse types of spatial data and explores the methods applied in hazard and risk assessments, with volcanic eruptions serving as a specific example. The rapid development of scientific research and the advancement of Earth Observation satellites in recent years have revolutionized the concepts of geologists and researchers. These satellites now play an indispensable role in supporting first responders during major disasters. The coordination of satellite deployment ensures a swift response along with allowing for the timely delivery of critical images. In tandem, remote sensing technologies and geographic information systems (GIS) have emerged as essential tools for geospatial analysis. The application of remote sensing and GIS for the detection of natural disasters was examined through a review of academic papers, offering an analysis of how remote sensing is utilized to assess natural hazards and their link to climate change.

Recent progress in tsunami deposit investigations in Taiwan

Abstract Identifying deposits of modern/historical and prehistorical tsunamis in Taiwan has been successful in the past two decades and has substantially increased the extant tsunami catalogs, which have been limited in the past four centuries due to scarce and ambiguous historical accounts. In this review, the initiation of the investigation is briefly discussed, partly in response to the latest catastrophic tsunamis in the Indo-Pacific and the stimulated public concern in Taiwan. Major developments and results of the investigation include the onset of the first stage before 2010, with findings in Keelung, the eastern coast, and Lanyu Island, and the second/ongoing stage after 2013, with findings in the northern and eastern coasts and Penghu Islands. These findings contributed to validating the debated historical events, expanding the event number and time span of the tsunami catalog, and elaborating on tsunami processes, which collectively enabled the delineation of the recurrence time intervals between events. Limitations, uncertainty, further contributions, and feedback are discussed including insights into the regional western Pacific hazards of tsunamis, earthquakes, and volcanic eruptions; the principles of recognizing tsunami deposits and processes; and the propositions of future studies and hazard mitigations in Taiwan.

Radiative impact of the Hunga stratospheric volcanic plume: role of aerosols and water vapor over Réunion Island (21° S, 55° E)

Abstract. This study attempts to quantify the radiative impact over Réunion Island (21° S, 55° E) in the southern tropical Indian Ocean of the aerosols and water vapor (WV) injected into the stratosphere by the eruption of the Hunga underwater volcano in the South Pacific on 15 January 2022 . Ground-based lidar and satellite passive instruments are used to parameterize a state-of-the-art radiative transfer (RT) model for the first 13 months after the volcano eruption. The descending rate of the aerosol volcanic plume is −8 m d−1. At this rate, aerosols are expected to be present in the stratosphere until the first half of 2025. The overall aerosol and water vapor impact on the Earth's radiation budget for the whole period is negative (cooling, −0.82 ± 0.35 W m−2) and dominated by the aerosol impact (∼ 95 %; the remaining ∼ 5 % is due to the water vapor). At the Earth's surface, aerosols are the main drivers and produce a negative (cooling, −1.04 ± 0.36 W m−2) radiative impact. Water vapor has hardly any radiative effect at the surface. Between the short-term (months 2 to 4 after the eruption, February–April 2022) and mid-term (months 5 to 14 after the eruption, May 2022–February 2023) periods, the aerosol and water vapor radiative effect at the surface and top of atmosphere (TOA) reduces by 22 % and 25 %, respectively. During the mid-term period, heating / cooling (H / C) rate profiles show a clear vertical difference locally in the stratosphere between the aerosol warming impact (18 to 26 km) and the water vapor cooling (22 to 30 km). The resulting aerosol and water vapor heating / cooling rate profile follows an S-shaped curve with peaks slightly larger for the moist layer (−0.09 K d−1) than for the sulfate layer (+0.06 K d−1).

Three‐Dimensional Characterization of Global Ionospheric Disturbances During the 15 January 2022 Tonga Volcanic Eruption

AbstractThe global 3‐dimensional structure of the concentric traveling ionospheric disturbances (CTIDs) triggered by 2022 Tonga volcano was reconstructed by using the 3‐dimensional computerized ionospheric tomography (3DCIT) technique and extensive global navigation satellite system (GNSS) observations. This study provides the first estimation of the CTIDs vertical wavelengths, ∼736 km, which was much larger than the gravity wave (GW) vertical wavelength, 240–400 km, estimated using ICON neutral wind observations. Notable trend with the variation of azimuth was also found in horizontal speeds at 200 and 500 km altitudes and differences between them. These results imply that (a) the global propagation of Lamb waves determined the arrival time of local ionospheric disturbances, and (b) the arriving Lamb waves caused vertical atmospheric perturbations that are not typical of GWs, resulting in local thermospheric horizontal wave propagation which is faster than the Lamb wave propagation at lower altitudes.

Glacier speed-up as a possible precursor to volcanic eruptions at Mount Veniaminof, Alaska

Glacier speed-up as a possible precursor to volcanic eruptions at Mount Veniaminof, Alaska

Evolution of eruption rate between two caldera-forming eruptions in the Jemez Mountains volcanic field, New Mexico, USA

Rhyolites that erupted between the Otowi and Tshirege members of the Bandelier Tuff, known as the Valle Toledo Member, were investigated in the Jemez Mountains volcanic field to infer changes in eruptive rate and flux between two caldera-forming eruptions. Our analysis combines high-precision 40Ar/39Ar single-crystal laser-fusion dating of sanidine, matrix glass compositions and mineralogy of pumice, depositional textures, and volumetric estimates of erupted rhyolites to present a revised Valle Toledo Member eruptive chronology that integrates our observations with those of previous studies. With the improved temporal resolution of our high-precision eruption ages (median 2σ uncertainty of ±2.9 ka), the updated Valle Toledo Member eruption chronology consists of at least 42 temporally or mineralogically distinct eruptions that we group into four periods of time based on eruption rate. Within the first 8.1 ± 5.1 kyr (~1605–1597 ka) that followed the Otowi caldera-forming eruption at 1605.4 ± 2.3 ka, six eruptions are recognized. This suggests an average recurrence interval on the order of 1.4 ± 0.9 kyr. Twenty-seven eruptions occurred during the next 194.4 ± 5.1 kyr (from ~1597–1403 ka) and the average recurrence interval increased to 7.2 ± 0.2 kyr. Following this second period of slower eruption rate, a previously unrecognized eruption hiatus of up to 162.4 ± 3.1 kyr occurred from 1402.9 ± 2.3 ka to 1240.5 ± 2.1 ka. Resumption of volcanic activity is characterized by a series of at least nine volcanic eruptions during the next 8.6 ± 2.5 kyr, culminating in the eruption of the 400 km3 Tshirege Member of the Bandelier Tuff and formation of Valles caldera at 1231.9 ± 1.3 ka. This last phase of pre-caldera activity has the shortest observed average recurrence interval (1.0 ± 0.3 kyr) and greatest eruptive flux (≥ 0.4 ± 0.2 km3/kyr) that occurred between the two caldera-forming eruptions. We interpret the shifts in eruption rate and flux following the 162.4 ± 3.1 kyr eruption hiatus, in addition to mineralogical changes present in post-hiatus rhyolites, as indicators that the Bandelier system was trending towards another major eruption. The magmatic system may have grown gradually throughout the ca. 162 kyr period of volcanic repose; however, the heightened eruption rate in the ca. 10 kyr before caldera collapse is consistent with relatively rapid growth of the magmatic system before the Tshirege event as previously proposed by other studies. Furthermore, the new dataset is consistent with prior geochronology studies of the region that show the four largest explosive eruptions in the Jemez field were all proceeded by very slow eruptive rates or hiatuses. This demonstrates that sequences of heightened volcanic activity can initiate on rapid geological timescales from states of volcanic quiescence in the Bandelier system.

The Relative Contributions of Internal Variability and External Forcing to Pacific Walker Circulation over the Last Millennium

Abstract Pacific Walker circulation (PWC) is an important component of tropical atmospheric circulation. Current studies have mainly focused on PWC changes over recent decades and the near future, while less effort has been devoted to long-term PWC variations. In this study, we investigate PWC changes over the last millennium (LM) based on the Community Earth System Model LM Ensemble (CESM-LME). The simulated PWC variations show no significant trend but do reveal decadal fluctuations during the LM, which underestimate the strengthened Little Ice Age (LIA)–Medieval Climate Anomaly (MCA) PWC differences indicated by proxy-based reconstructions. A quantitative estimation of the contributions made to PWC variability from internal variability and external forcing is conducted by using multiple linear regression (MLR) analysis. The internal variabilities contribute approximately 80% to the changes in PWC during the LM, among which the interdecadal Pacific oscillation (IPO) has the largest contribution. In the positive phase of the IPO, the Indo-Pacific sea level pressure (SLP) gradient decreases, and anomalous westerlies occur in the tropical western Pacific, corresponding to a weakened PWC. The relationships between the IPO and PWC show multidecadal-to-centennial fluctuations, suggesting that other internal modes or external forcings may have modulated the IPO–PWC relationship. Volcanic forcing is also an important contributor to PWC variability during the LM. The simulated PWC significantly weakens and lasts for 1–2 years after large volcanic eruptions. The El Niño–like SST pattern and the corresponding zonal SLP gradient lead to the PWC weakening following large volcanic eruptions. Significance Statement As one of the most active components of tropical atmospheric circulation, Pacific Walker circulation (PWC) can significantly modulate global climate through atmospheric teleconnections. Previous studies have mainly focused on PWC variability over recent warm periods and future changes. However, understanding of PWC changes is currently lacking due to limited instrumental observations. The last millennium (LM) has a rich archive of proxy records that give us a longer perspective on climate variability and change, which is an excellent period for understanding the long-term mechanisms and changes in PWC. In this study, we use simulations from the CESM-LME to quantify the relative importance of internal variability and external forcings to PWC variations during the LM. The simulated PWC variations show no significant trend but decadal fluctuations, which underestimates the reconstructed PWC variations during the LM. The internal variabilities contribute approximately 80% to the changes in PWC, among which the interdecadal Pacific oscillation (IPO) has the largest contribution. External forcing, especially the contribution made by volcanic forcing, is also nonnegligible. Both the positive phase of the IPO and large tropical volcanic eruptions could trigger El Niño–like SST anomalies, accompanied by a decreased Indo-Pacific SLP gradient and a weakened PWC.

Analysis of student preparedness behaviour in facing lava rainfall disasters

Students are vulnerable to natural disasters. This is further exacerbated by the large number of schools located in disaster-prone areas, so student preparedness behaviour needs to be continuously improved. This study aims to determine the level of preparedness, awareness, action, and effect students have in dealing with the volcanic eruption of Mount Merapi. This study used quantitative research; the instrument used was a questionnaire made by taking samples at SMK Muhammadiyah 1 Salam. The sampling method was stratified random sampling from students in grades 10, 11, and 12. The assessment of students’ preparedness behaviour in dealing with rain lava was based on four variables: preparedness, awareness, action, and affect. Then, each variable was analyzed using descriptive statistics and multiple correlation analysis. The study results show that the relationship between preparedness, awareness, action, and affect shows a strong level of closeness with a value of 0.680. The study identifies critical gaps in knowledge and behavioural responses that must be addressed to enhance overall preparedness behaviour. The results underscore the importance of targeted educational interventions and community engagement in fostering a culture of resilience among students in disaster-prone areas.

Management of inclusive data for Merapi volcano eruption risk areas using participatory action research (PAR) with the perspective of women, the elderly, and persons with disabilities

This research, conducted by Plan Indonesia, YAKKUM Emergency Unit (YEU), and the Klaten Association of Disabled People (PPDK), with support from ELRHA, UKAid, the Norwegian Ministry of Foreign Affairs, and Plan International, aimed to foster inclusive research by integrating Views from the Frontline (VFL) guidelines with the Feminist Participatory Action Research (FPAR) method. The study involved women, people with disabilities, including youth and children with disabilities, as well as the elderly. Research participants included people with disabilities, the elderly, health cadres, and elderly cadres, and was conducted from May to December 2023 in the disaster-prone areas of Kemalang and Manisrenggo Districts, Central Java. Data analysis was done through triangulation, utilizing multi-party meetings to verify findings based on various times, places, and participants. The research identified types of threats related to the Merapi volcano eruption and needs based on the Humanitarian Inclusion Standard, focusing on gender, age, and ability. Key recommendations include integrating disaster risk management approaches with community-led action plans, enhancing inclusion, promoting local leadership, and developing a national advocacy strategy to increase community involvement in disaster risk reduction efforts, particularly for women, the elderly, and people with disabilities.

Sporadic <i>E</i> responds to the 2022 Tonga volcano eruptions recorded by the Meridian Project

Sporadic <i>E</i> responds to the 2022 Tonga volcano eruptions recorded by the Meridian Project

Penerapan Collective Risk Model dalam Penentuan Premi Asuransi Bencana Alam

Indonesia is prone to natural disasters such as volcanic eruptions, earthquakes, and tsunamis due to tectonic activity involving the Indo-Australian and Eurasian plates. Therefore, the government introduced natural disaster insurance in 2018 to mitigate financial losses caused by such events. This study employs the Collective Risk Model (CRM) to determine premium rates. The Poisson process and Gamma distribution are utilized to estimate the frequency and severity of natural disasters. Estimation is performed using Maximum Likelihood Estimation (MLE), while premiums are calculated based on the expected value and variance of aggregate risk using the Expected Value Principle and the Standard Deviation Principle. The results show that the expected value and variance of claim frequency are both . Furthermore, claims for losses follow the Gamma distribution, with an expected value and variance of and . The mean and variance of aggregate claims are Rp and Rp . The Standard Deviation Principle produces lower premiums than the Expected Value Principle under the same loading factor.

The 1831 CE mystery eruption identified as Zavaritskii caldera, Simushir Island (Kurils)

Polar ice cores and historical records evidence a large-magnitude volcanic eruption in 1831 CE. This event was estimated to have injected ~13 Tg of sulfur (S) into the stratosphere which produced various atmospheric optical phenomena and led to Northern Hemisphere climate cooling of ~1 °C. The source of this volcanic event remains enigmatic, though one hypothesis has linked it to a modest phreatomagmatic eruption of Ferdinandea in the Strait of Sicily, which may have emitted additional S through magma-crust interactions with evaporite rocks. Here, we undertake a high-resolution multiproxy geochemical analysis of ice-core archives spanning the 1831 CE volcanic event. S isotopes confirm a major Northern Hemisphere stratospheric eruption but, importantly, rule out significant contributions from external evaporite S. In multiple ice cores, we identify cryptotephra layers of low K andesite-dacite glass shards occurring in summer 1831 CE and immediately prior to the stratospheric S fallout. This tephra matches the chemistry of the youngest Plinian eruption of Zavaritskii, a remote nested caldera on Simushir Island (Kurils). Radiocarbon ages confirm a recent (<300 y) eruption of Zavaritskii, and erupted volume estimates are consistent with a magnitude 5 to 6 event. The reconstructed radiative forcing of Zavaritskii (-2 ± 1 W m-2) is comparable to the 1991 CE Pinatubo eruption and can readily account for the climate cooling in 1831-1833 CE. These data provide compelling evidence that Zavaritskii was the source of the 1831 CE mystery eruption and solve a confounding case of multiple closely spaced observed and unobserved volcanic eruptions.

Dynamic treeline and cryosphere response to pronounced mid-Holocene climatic variability in the US Rocky Mountains

Climate-driven changes in high-elevation forest distribution and reductions in snow and ice cover have major implications for ecosystems and global water security. In the Greater Yellowstone Ecosystem of the Rocky Mountains (United States), recent melting of a high-elevation (3,091 m asl) ice patch exposed a mature stand of whitebark pine (Pinus albicaulis) trees, located ~180 m in elevation above modern treeline, that date to the mid-Holocene (c. 5,950 to 5,440 cal y BP). Here, we used this subfossil wood record to develop tree-ring-based temperature estimates for the upper-elevation climate conditions that resulted in ancient forest establishment and growth and the subsequent regional ice-patch growth and downslope shift of treeline. Results suggest that mid-Holocene forest establishment and growth occurred under warm-season (May-Oct) mean temperatures of 6.2 °C (±0.2 °C), until a multicentury cooling anomaly suppressed temperatures below 5.8 °C, resulting in stand mortality by c. 5,440 y BP. Transient climate model simulations indicate that regional cooling was driven by changes in summer insolation and Northern Hemisphere volcanism. The initial cooling event was followed centuries later (c. 5,100 y BP) by sustained Icelandic volcanic eruptions that forced a centennial-scale 1.0 °C summer cooling anomaly and led to rapid ice-patch growth and preservation of the trees. With recent warming (c. 2000-2020 CE), warm-season temperatures now equal and will soon exceed those of the mid-Holocene period of high treeline. It is likely that perennial ice cover will again disappear from the region, and treeline may expand upslope so long as plant-available moisture and disturbance are not limiting.

Predicting the presence of tephra layers in lacustrine deposits using spectral gamma ray data: An example from Lake Chalco, Mexico City.

Spectral gamma ray borehole logging data can yield insights into the physical properties of lake sediments, serving as a valuable proxy for assessing climate and environmental changes. The presence of tephra layers resulting from volcanic ash deposition is not related to climate and environmental conditions. As a result, these layers pose challenges when attempting to analyze paleoclimate and environmental time series. Gamma rays are composed of photons, which are elementary particles of electromagnetic radiation. Tephra layers emit photons at specific energy levels that create a distinct pattern in their gamma-ray energy spectrum. The gamma-ray signature of tephra layers varies depending on the stage of the volcanic eruption. Additionally, there is a significant difference between the gamma-ray signature emitted by tephra layers and that of the background lake sediments. A composite signature can be used to predict tephra layers from background sediments by combining several gamma-ray signatures of tephra layers at different depths. We propose five-step protocol for detecting tephra layers within sediments through the utilization of gamma-ray spectroscopy. This protocol is based on a combination of physical aspects of gamma-ray spectroscopy and geological information specific to the lake system being studied. A subset of the training dataset is used, consisting of known tephra and non-tephra layers. The protocol involves identifying similarities between known tephra layers, analyzing differences in gamma-ray signals between tephra and non-tephra layers, and studying the composition of energy channels at various depths within the training dataset. Multiple linear regression models are used to predict the relationship between the composition of tephra layers as a dependent variable and the constituent energy channels of the gamma-ray signal as independent variables. The proposed protocol has the potential to accurately detect and identify thick tephra layers (> 10 cm in thickness) based on the rate of spectral gamma ray measurement in sedimentary sequences. This approach could enhance stratigraphic resolution by enabling finer subdivision of layers in an interior basin.

Time-series InSAR measurement using ICOPS and estimation of along-track surface deformation using MAI during the 2021 eruption of Fagradalsfjall Volcano, Iceland

The eruption in Fagradalsfjall Volcano, located in Reykjanes Peninsula, Iceland, from several centuries’ dormant states, occurred for the first time on March 19, 2021. Observations of Fagradalsfjall Volcano were conducted in 2021, and the eruption period lasted for six months until 18 September 2021. Six days pair of interferograms were generated from ninety synthetic aperture radar (SAR) data. Thus, the SAR data will be acquired from the Sentinel-1 satellite from January until December 2021. Time-series measurements were conducted using a combination of persistent scatterer (PS) and distributed scatterer (DS) points to produce denser measurement points (MPs) in the study area. The improved combined scatterers interferometry with optimized point scatterers (ICOPS) algorithm is the time-series method that utilizes both PS and DS MPs and optimizes those combined MPs using a deep learning algorithm over different temporal intervals and using a statistical clustering approach to optimize the MPs spatially. Validation was conducted by comparing the ICOPS result with GPS measurement in Reykjavik. The comparison with the GPS measurement was performed to validate the line-of-sight (LOS) deformation from the ICOPS measurement, which resulted in an RMSE value of about 0.58 cm, which is considered a good correlation. Besides the time-series Interferometry SAR (InSAR) measurement, we used the integrated InSAR and multiple aperture interferometry (MAI) methods to estimate both LOS and along-track surface deformation, respectively, during the Fagradalsfjall, Iceland volcanic eruption. A pair of ALOS-2 data was used between 28 February 2021 and 23 May 2021. The result from the MAI method shows a deformation of approximately ± 2 mm in the azimuth direction around Fagradalsfjall Volcano. The deformation around Fagradalsfjall Volcano was suggested to be due to the activity of the magma reservoir beneath the Earth’s surface, which was formed by dike intrusion. The analysis of the seismicity in Fagradalsfjall was discussed by visualization of the distribution of earthquakes during the deformation occurrence. Further analysis can be conducted by applying multitrack analysis to find the 3D deformation pattern due to the eruption.

Simultaneous Observation of Equatorial Plasma Bubbles and Traveling Ionospheric Disturbances Over Indonesia Following the 15 January 2022 Tonga Volcano Eruption

AbstractWe report our analysis of multi‐diagnostic ionospheric observations over Indonesia following the 15 January 2022 Tonga volcano eruption. Observation data from the Indonesian global navigation satellite system (GNSS) CORS network, ionosondes, and GNSS ionospheric scintillation and TEC monitor receivers, in conjunction with the Himawari‐8 satellite imagery, were used in the analysis. The Lamb waves from the eruption, traveling at 310 m/s, reached eastern part of Indonesia (5,000 km from Tonga) approximately 4 hr after the eruption. The Lamb waves traversed the Indonesian region for 4 hr and 40 min, around sunset period. As a result, some unseasonal equatorial plasma bubbles (EPBs) occurred over this longitude sector, with an interesting initial development pattern. There was a directional split in the zonal drift velocity of these EPBs, where some EPBs drifted eastward with a velocity of 138.0 6.9 m/s and others westward with a velocity of 39.6 2.0 m/s. At the same time, traveling ionospheric disturbances (TIDs) from the Tonga eruption also propagated over the Indonesian region with a velocity of 434.6 21.7 m/s. In the total electron content (TEC) data, interactions between EPBs and TIDs were observed over the region. There were enhancements in the rate‐of‐TEC index (ROTI) and scintillation index, indicating the presence of ionospheric density irregularities. A turbulent ionospheric F‐layer, due to these EPBs and TIDs, caused either spread‐F echoes or a loss of F‐region traces in the ionograms. An intensification of sporadic‐E layer, lasting for a few hours, was also observed in the ionograms.

PENGARUH SOSIAL MEDIA TERHADAP MITIGASI BENCANA BANJIR

Indonesia frequently experiences natural disasters, especially floods. The National Disaster Management Agency (BNPB) utilizes social media to reduce the likelihood of disasters and disseminate information about them. Disaster mitigation is an effort to reduce the risks and impacts of disasters on communities in disaster-prone areas. These disasters can include natural events such as earthquakes, tsunamis, floods, or volcanic eruptions, as well as human-induced disasters such as social conflicts and terrorism. The goal of disaster mitigation is to minimize the risk of fatalities and injuries to residents and reduce losses when hazards occur in the future. This includes mitigating economic losses and damage to public sector infrastructure. The objective of this study is to gain an understanding of how social media can be leveraged to disseminate information about natural disasters and to build public awareness regarding potential disaster risks in the future. Keywords: Disaster mitigation, Floods, Social media, Impact, Society