At Aso volcano, phreatic and phreatomagmatic eruptions have repeatedly caused volcanic disasters with fatalities near the crater. While it is important to conduct research on eruption forecasting for ...reducing the risk to tourists and climbers of this volcano, it is also important to improve disaster prevention literacy regarding the volcanic eruptions. To improve disaster prevention literacy, it is important to elucidate the mechanisms of volcanic disasters based on case studies. In this study, the author chronologically summarizes the incident of the phreatic eruption that occurred in 2021 at Aso volcano. Although the Japan Meteorological Agency issued volcanic activity information sequentially as the volcanic activity increased, this information did not lead to prompt and effective closure of mountain trails. There was also a problem with the collection of volcanic information by climbers. It became clear that information on volcanic activity was not used effectively by either those regulating the mountain trails or those using them. Efforts should be made to resolve these issues in the future.
We estimate the mass and energy budgets for the 2018 phreatic eruption of Mt. Motoshirane on Kusatsu–Shirane volcano, Japan, based on data obtained from a network of eight tiltmeters and weather ...radar echoes. The tilt records can be explained by a subvertical crack model. Small craters that were formed by previous eruptions are aligned WNW–ESE, which is consistent with the strike of the crack modeled in this study. The direction of maximum compressive stress in this region is horizontal and oriented WNW–ESE, allowing fluid to intrude from depth through a crack with this orientation. Based on the crack model, hypocenter distribution, and MT resistivity structure, we infer that fluid from a hydrothermal reservoir at a depth of 2 km below Kusatsu–Shirane volcano has repeatedly ascended through a pre-existing subvertical crack. The inflation and deflation volumes during the 2018 eruption are estimated to have been 5.1 × 10
5
and 3.6 × 10
5
m
3
, respectively, meaning that 1.5 × 10
5
m
3
of expanded volume formed underground. The total heat associated with the expanded volume is estimated to have been ≥ 10
14
J, similar to or exceeding the annual heat released from Yugama Crater Lake of Mt. Shirane and that from the largest eruption during the past 130 year. Although the ejecta mass of the 2018 phreatic eruption was small, the eruption at Mt. Motoshirane was not negligible in terms of the energy budget of Kusatsu–Shirane volcano. A water mass of 0.1–2.0 × 10
7
kg was discharged as a volcanic cloud, based on weather radar echoes, which is smaller than the mass associated with the deflation. We suggest that underground water acted as a buffer against the sudden intrusion of hydrothermal fluids, absorbing some of the fluid that ascended through the crack.
Kusatsu-Shirane volcano hosts numerous thermal springs, fumaroles, and the crater lake of Yugama. Hence, it has been a particular study field for hydrothermal systems and phreatic eruptions. On 23 ...January 2018, a phreatic eruption occurred at the Motoshirane cone of Kusatsu-Shirane, where no considerable volcanic activity had been reported in observational and historical records. To understand the eruption process of this unique event, we analyzed seismic, tilt, and infrasound records. The onset of surface activity accompanied by infrasound signal was preceded by volcanic tremor and inflation of the volcano for ~ 2 min. Tremor signals with a frequency band of 5–20 Hz remarkably coincide with the rapid inflation. We apply an amplitude source location method to seismic signals in the 5–20 Hz band to estimate tremor source locations. Our analysis locates tremor sources at 1 km north of Motoshirane and at a depth of 0.5–1 km from the surface. Inferred source locations correspond to a conductive layer of impermeable cap-rock estimated by magnetotelluric investigations. An upper portion of the seismogenic region suggests hydrothermal activity hosted beneath the cap-rock. Examined seismic signals in the 5–20 Hz band are typically excited by volcano-tectonic events with faulting mechanism. Based on the above characteristics and background, we interpret that excitation of examined volcanic tremor reflects small shear fractures induced by sudden hydrothermal fluid injection to the cap-rock layer. The horizontal distance of 1 km between inferred tremor sources and Motoshirane implies lateral migration of the hydrothermal fluid, although direct evidence is not available. Kusatsu-Shirane has exhibited unrest at the Yugama lake since 2014. However, the inferred tremor source locations do not overlap active seismicity beneath Yugama. Therefore, our result suggests that the 2018 eruption was triggered by hydrothermal fluid injection through a different pathway from that has driven unrest activities at Yugama.
The thermal activity of a magmatic–hydrothermal system commonly changes at various stages of volcanic activity. Few studies have provided an entire picture of the thermal activity of such a system ...over an eruptive cycle, which is essential for understanding the subsurface heat transport process that culminates in an eruption. This study quantitatively evaluated a sequence of thermal activity associated with two phreatic eruptions in 2021 at Aso volcano. We estimated plume-laden heat discharge rates and corresponding H
2
O flux during 2020–2022 by using two simple methods. We then validated the estimated H
2
O flux by comparison with volcanic gas monitoring results. Our results showed that the heat discharge rate varied substantially throughout the eruptive cycle. During the pre-eruptive quiescent period (June 2020–May 2021), anomalously large heat discharge (300–800 MW) were observed that were likely due to enhanced magma convection degassing. During the run-up period (June–October 2021), there was no evident change in heat discharge (300–500 MW), but this was accompanied by simultaneous pressurization and heating of an underlying hydrothermal system. These signals imply progress of partial sealing of the hydrothermal system. In the co-eruptive period, the subsequent heat supply from a magmatic region resulted in additional pressurization, which led to the first eruption (October 14, 2021). The heat discharge rates peaked (2000–4000 MW) the day before the second eruption (October 19, 2021), which was accompanied by sustained pressurization of the magma chamber that eventually resulted in a more explosive eruption. In the post-eruptive period, enhanced heat discharge (~ 1000 MW) continued for four months, and finally returned to the background level of the quiescent period (< 300 MW) in early March 2022. Despite using simple models, we quantitatively tracked transient thermal activity and revealed the underlying heat transport processes throughout the Aso 2021 eruptive activity.
Graphical abstract
We investigated temporal changes in the rock-magnetic properties of volcanic ash ejected from the Aso Nakadake volcano during a sequence of ash eruptions from 2019 to 2020. For 39 volcanic ash ...samples, magnetic hysteresis parameters, including saturation magnetization (
M
s
), saturation remanent magnetization (
M
rs
), coercivity (
B
c
), and coercivity of remanence (
B
cr
), were obtained. Curie temperature (
T
c
) of the samples was also estimated using thermomagnetic analyses. Titanium-rich and -poor titanomagnetites were the dominant magnetic minerals in the volcanic ash, of which the titanium-rich phase was dominant. Systematic magnetic measurements of the volcanic ash ejected during the 1-year eruption event indicate that temporal changes in the hysteresis parameters occurred throughout the event. These temporal changes suggest that the
M
rs
/
M
s
and
B
c
values of the volcanic ash increased considerably during several periods. The clear increases in
M
rs
/
M
s
and
B
c
, associated with the central peak in FORC diagrams, indicate that non-interacting single-domain grains increased. For these high
M
rs
/
M
s
and
B
c
samples, thermal demagnetizations of 3-axis IRM show that the low unblocking-temperature component up to 250–300 °C has apparently higher coercivity, suggesting that the above-mentioned, non-interacting single-domain grains are Ti-rich titanomagnetite. Interestingly, the high
M
rs
/
M
s
and
B
c
values were synchronous with observations of volcanic glow. These results suggest that changes in the magnetic properties of titanomagnetite grains in volcanic ash reflect changes in physical conditions from the vent to the conduit of the volcano.
Graphical Abstract
Neurointestinal diseases cause significant morbidity and effective treatments are lacking. This study aimes to test the feasibility of transplanting autologous enteric neural stem cells (ENSCs) to ...rescue the enteric nervous system (ENS) in a model of colonic aganglionosis. ENSCs are isolated from a segment of small intestine from Wnt1::Cre;R26iDTR mice in which focal colonic aganglionosis is simultaneously created by diphtheria toxin injection. Autologous ENSCs are isolated, expanded, labeled with lentiviral-GFP, and transplanted into the aganglionic segment in vivo. ENSCs differentiate into neurons and glia, cluster to form neo-ganglia, and restore colonic contractile activity as shown by electrical field stimulation and optogenetics. Using a non-lethal model of colonic aganglionosis, our results demonstrate the potential of autologous ENSC therapy to improve functional outcomes in neurointestinal disease, laying the groundwork for clinical application of this regenerative cell-based approach.
We analyzed continuous Global Positioning System (GPS) data from Sinabung to capture and model the migration of magma from the pre-eruptive and syn-eruptive time period between June 2013 and January ...2016. We divided this time into four periods of significant deformation: two extensional stages followed by two contractional stages. Using a grid search method, we determined the location and volume change of a Mogi source for each deformation stage. Cumulative volume changes during the contraction periods were approximated by an exponentially decaying function with time. Period 1 began in June 2013 with slight extension, for which an inflation source was modeled at a depth of 3–8km below sea level (bsl) and a volume change of 0.3–1.8Mm3. Seismicity in period 1 was marked by a notable increase in deep high frequency volcano tectonic earthquakes (VTs) beginning in July 2013 and shallow VTs in September 2013. Period 2 began in late October 2013 with accelerated extension, with at least 1cm extension in the baseline length. During period 2 the modeled inflation source ascended to a shallower depth of 0.9 (0.4–2.1) km below sea level (bsl) beneath Sinabung with a change in volume of +0.39 (+0.18–+0.60) Mm3, and with accelerated rates of volume increase during the time period when the magma migrated to the surface. Seismicity during period 2 was marked first by an increase in the incidence of shallow volcano-tectonic (VT) earthquakes and later by repetitive self-similar hybrid events as the magma migrated to the surface. Period 3 began in January 2014, after the appearance of the lava dome, and was marked by rapid steady contraction of ~3cm through March 2014. The modeled source located at 8.4 (7.4–9.9) km bsl beneath the eastern flank of Sinabung with a volume change of −20.51 (−26.89 to −14.12) Mm3. Period 4 began in April 2014 with decelerating contraction, and the modeled deformation center shifted to the northeast, reaching a depth of 12.2 (10.1–14.8) km bsl between Sinabung and Sibayak volcanoes and a change in volume of −88.26 (−123.87 to −52.66) Mm3. Approximately 2/3 of the total volume change related to contraction occurred between January 2014 and May 2016, and the current activity of Sinabung is expected to decrease gradually and almost terminate in the early 2020s, assuming no new intrusion or deformation rate changes. Both of the eruptions at Sinabung in 2010 and Unzen in 1991–1995 show characteristics of ground inflation and subsequent deflation, indicating magma migration and effusion processes similar to the current Sinabung activity. The inflation before the 2010 Sinabung eruptions likely started before 2007 and is an indication of magma intrusion before the 2010 and 2013 eruptions.
•We analyzed continuous data of GPS at Sinabung volcano, Indonesia.•Extension before the lava dome appearance and subsequent contraction was detected.•The inflation sources migrated from deeper part to shallower beneath the summit.•The deflation sources moved away to easterly direction to deeper.•The exponential decay function allows estimation of the trend of eruptivity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Chronic low-grade inflammation in visceral adipose tissues triggers the development of obesity-related insulin resistance, leading to the metabolic syndrome, a serious health condition with higher ...risk of cardiovascular disease, diabetes, and stroke. In the present study, we investigated whether Sprouty-related EVH1-domain-containing protein 2 (Spred2), a negative regulator of the Ras/Raf/ERK/MAPK pathway, plays a role in the development of high fat diet (HFD)-induced obesity, adipose tissue inflammation, metabolic abnormalities, and insulin resistance. Spred2 knockout (KO) mice, fed with HFD, exhibited an augmented body weight gain, which was associated with enhanced adipocyte hypertrophy in mesenteric white adipose tissue (mWAT) and deteriorated dyslipidemia, compared with wild-type (WT) controls. The number of infiltrating macrophages with a M1 phenotype, and the crown-like structures, composed of macrophages surrounding dead or dying adipocytes, were more abundant in Spred2 KO-mWAT compared to in WT-mWAT. Exacerbated adipose tissue inflammation in Spred2 KO mice led to aggravated insulin resistance and fatty liver disease. To analyze the mechanism(s) that caused adipose tissue inflammation, cytokine response in mWAT was investigated. Stromal vascular fraction that contained macrophages from Spred2 KO-mWAT showed elevated levels of tumor necrosis factor α (TNFα) and monocyte chemoattractant protein-1 (MCP-1/CCL2) compared with those from WT-mWAT. Upon stimulation with palmitate acid (PA), bone marrow-derived macrophages (BMDMs) derived from Spred2 KO mice secreted higher levels of TNFα and MCP-1 than those from WT mice with enhanced ERK activation. U0126, a MEK inhibitor, reduced the PA-induced cytokine response. Taken together, these results suggested that Spred2, in macrophages, negatively regulates high fat diet-induced obesity, adipose tissue inflammation, metabolic abnormalities, and insulin resistance by inhibiting the ERK/MAPK pathway. Thus, Spred2 represents a potential therapeutic tool for the prevention of insulin resistance and resultant metabolic syndrome.
Neurointestinal diseases represent a significant challenge in clinical management with current palliative approaches failing to overcome disease and treatment-related morbidity. The recent progress ...with cell therapy to restore missing or defective components of the gut neuromusculature offers new hope for potential cures. This review discusses the progress that has been made in the sourcing of putative stem cells and the studies into their biology and therapeutic potential. We also explore some of the practical challenges that must be overcome before cell-based therapies can be applied in the clinical setting. Although a number of obstacles remain, the rapid advances made in the enteric neural stem cell field suggest that such therapies are on the near horizon.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
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