Initial Eruption Research Articles

Unique seismic and eruption precursors to the 1996 and ongoing magmatic eruptions of Popocatépetl: Coupled and fluidized bed events

We describe three unique types of seismicity at Popocatépetl volcano that accompanied the initial vent-clearing eruptive activity in December 1994 through the eruption of the first two domes in 1996. We identify and describe two types of coupled events, 1) spasmodic burst coupled events, a burst of volcano tectonic (VT) events coupled with a large eruptive explosion (21 December 1994 and 5 March 1996), and 2) explosion-couplet coupled events, a pair of events with a deeper first event and whose second event correlates with a small gas emission or explosion. Explosion-couplets occurred with the onset of magmatic ash dominated eruptions and their properties are very useful for forecasting magmatic eruptions at Popocatépetl volcano. Measurable quantities including the time between the first and second phase, daily numbers of events, and the amplitude ratio between the second and first phase systematically changed as the first two domes approached the surface between March and June 1996. Interevent times decreased from many tens of seconds to a few seconds, while amplitude ratios increased from about 2 to 10 or more. Event numbers increased prior to and during initial dome extrusion. These changes were used to forecast the eruption of the first two domes. We also report on another unusual type of low frequency seismicity that accompanied emissions called fluidized bed events. Fluidized bed events occurred following the initial eruption on 21 December 1994, beginning mid-January 1995, when SO2 emissions were initially elevated, and the conduit was open. Fluidized bed events began to wane in late March through the end of May 1995 as did SO2 emissions. Consistent gas, visual and seismic observations by Centro Nacional de Prevención de Desastres (CENAPRED) enabled the direct correlation of the gas, magma, and seismic phenomena.

New bulk rock and age data on the changes in magma evolution during the Miocene, Galatean volcanic area, central Anatolia, Turkey: A review

The Galatean Volcanic Province (GVP) lies within the Sakarya tectonic belt in the northwest of central Anatolia, Turkey, south of the North Anatolian Fault, cropping out over 12,000 km2. It consists of Early Miocene intermediate to acid lavas, pyroclastic rocks, volcaniclastic deposits, and Late Miocene OIB-like basalts. Our study is based on new bulk geochemistry, SrNd isotopes, and 40Ar/39Ar dating of the volcanic rocks from the south-western part of GVP, but integrates all the available previous data to understand how magmas evolved in the post-collisional geodynamic condition in the GVP. The initial eruptions were rhyolitic, as domes or pyroclastic deposits (Group 1) and basaltic lavas (Group 2) during the Early Miocene. Group 2 is also represented by large volumes of basaltic-andesitic, trachyandesite-dacite/trachydacite lava flows, small intrusions, and pyroclastic deposits as generated between 21 and 14 Ma. Relatively low 87Sr/86Sr ratios (0.705–0.706) of the early rhyolites (Group 1), similar to all the rocks from Group (2), suggest the generation of hybrid melts with variable contributions of mantle-derived and crustal material. The volcanic activity ends with OIB-like basalts (11–7 Ma) showing the lowest 87Sr/86Sr (∼0.703) suggesting an asthenospheric origin.The geodynamic model, based on post-Cyprian slab rollback, results in long-term (22–13 Ma) post-collisional delamination/drip processes that support magmatism. This magmatism is generated in the lithospheric mantle, with the formation of basaltic melts and acid hybrid melts showing variable contributions of mantle-derived and crustal materials in a complex trans-crustal magma plumbing system. Complex mixing of various intra-crustal magmas and fractional crystallization processes generated a huge volume of volcanic rocks. The Late Miocene small-volume OIB basalts were asthenospheric melts that during the late stage recorded localized decompression melting processes.

Global Coronal Plasma Diagnostics Based on Multislit Extreme-ultraviolet Spectroscopy

Full-disk spectroscopic observations of the solar corona are highly desired to forecast solar eruptions and their impact on planets and to uncover the origin of solar wind. In this paper, we introduce a new multislit design (five slits) to obtain extreme-ultraviolet (EUV) spectra simultaneously. The selected spectrometer wavelength range (184–197 Å) contains several bright EUV lines that can be used for spectral diagnostics. The multislit approach offers an unprecedented way to efficiently obtain the global spectral data but the ambiguity from different slits should be resolved. Using a numerical simulation of the global corona, we primarily concentrate on the optimization of the disambiguation process, with the objective of extracting decomposed spectral information of six primary lines. This subsequently facilitates a comprehensive series of plasma diagnostics, including density (Fe xii 195.12/186.89 Å), Doppler velocity (Fe xii 193.51 Å), line width (Fe xii 193.51 Å), and temperature diagnostics (Fe viii 185.21 Å, Fe x 184.54 Å, Fe xi 188.22 Å, and Fe xii 193.51 Å). We find a good agreement between the forward modeling parameters and the inverted results at the initial eruption stage of a coronal mass ejection, indicating the robustness of the decomposition method and its immense potential for global monitoring of the solar corona.

Disparate Pb-isotopic ages of silicate and phosphate minerals in the diabasic angrite Northwest Africa 12320

Pb-isotopic dating of the recently discovered diabasic angrite Northwest Africa (NWA) 12320 yielded ages of 4564.17 ± 0.50 Ma and 4562.82 ± 0.37 Ma for acid-insoluble and soluble minerals respectively. These ages are calculated using measured 238U/235U ratios of soluble and insoluble minerals, thereby excluding the possibility that the apparent age difference is caused by internal U-isotopic variations. The age of the insoluble minerals is indistinguishable from published Pb isotopic ages of other medium-grained angrites SAH 99555 and D'Orbigny. The age of acid-soluble minerals is distinctly younger, with a 1.35 ± 0.62 Ma age gap between the PbPb ages of the two mineral fractions. The mineral hosts of U, Th and radiogenic Pb in the meteorite were identified through in-situ SIMS measurements of these elements in all minerals. The principal carriers of U, Th and radiogenic Pb are acid insoluble Al-Ti-rich augite and soluble Si-rich phosphate. Closure temperatures for diffusion of radiogenic Pb in these minerals are calculated to be respectively 820 ± 90 °C and 450 ± 80 °C using the observed range of crystal dimensions and the published experimental data for Pb diffusion in augite and apatite. The age difference between the pyroxene and phosphates has two potential explanations: (1) a late reheating event >450 °C which may have re-set the UPb systematics of the phosphates but not the pyroxenes or (2) slow cooling of the rock from ∼450–820 °C. If slow cooling is the reason for the age difference, we can estimate a model cooling rate of 270 ± 150 °C/Ma over the estimated closure temperature range between pyroxenes and phosphates. This rate is ∼11 orders of magnitude slower than petrologic cooling rates of quenched angrites at temperatures above 1000 °C determined experimentally using the composition of Asuka 881371 groundmass (Keil, 2012), which is similar to NWA 12320 groundmass. If there was no late reheating event, the discrepancy between fast cooling rates at high temperatures near the solidus, followed by much slower cooling at lower temperatures, might have been caused by impact melting. It could also be attributed to the initial eruption of the source magma of NWA 12320 near the surface of the parent body, followed by burial due to subsequent eruptions.

Effects of coronal mass ejection orientation on its propagation in the heliosphere

Context. In the scope of space weather forecasting, it is crucial to be able to more reliably predict the arrival time, speed, and magnetic field configuration of coronal mass ejections (CMEs). From the time a CME is launched, the dominant factor influencing all of the above is the interaction of the interplanetary CME (ICME) with the ambient plasma and interplanetary magnetic field. Aims. Due to a generally anisotropic heliosphere, differently oriented ICMEs may interact differently with the ambient plasma and interplanetary magnetic field, even when the initial eruption conditions are similar. For this, we examined the possible link between the orientation of an ICME and its propagation in the heliosphere (up to 1 AU). Methods. We investigated 31 CME-ICME associations in the period from 1997 to 2018. The CME orientation in the near-Sun environment was determined using an ellipse-fitting technique applied to single-spacecraft data from SOHO/LASCO C2 and C3 coronagraphs. In the near-Earth environment, we obtained the orientation of the corresponding ICME using in situ plasma and magnetic field data. The shock orientation and nonradial flows in the sheath region for differently oriented ICMEs were investigated. In addition, we calculated the ICME transit time to Earth and drag parameter to probe the overall drag force for differently oriented ICMEs. The drag parameter was calculated using the reverse modeling procedure with the drag-based model. Results. We found a significant difference in nonradial flows for differently oriented ICMEs, whereas a significant difference in drag for differently oriented ICMEs was not found.

Crater formation during the onset of mud volcanism

AbstractThree-dimensional (3-D) seismic imaging was used to reveal >2.5-km-wide and >150-m-deep craters at the basal surface of 64 mud volcanoes out of a suite of 86, offshore Egypt. The craters were infilled soon after they formed by successive mud extrusions that combined to build mud volcanoes, as evidenced by onlap fill geometries of the earliest mud flows. We propose that the craters formed as the earliest manifestation of mud volcano formation. We infer that the energy required to excise in situ clays and sands buried and consolidated to depths over 150 m below the seafloor was provided by the highly vigorous venting of a dominantly gas and water mix during the initial eruption, in which gas column height was the critical factor. This primary phase of mud volcanism is rarely observed, and the findings presented here have significant implications for interpretations of the dynamism during this fundamental stage of mud volcano genesis.

Extreme Heights of 15 January 2022 Tonga Volcanic Plume and Its Initial Evolution Inferred from COSMIC-2 RO Measurements

The Hunga Tonga–Hunga Ha’apai underwater volcano (20.57° S, 175.38° W) violently erupted on 15 January 2022. The volcanic cloud’s top height and initial evolution are delineated by using the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC)-2 radio occultation (RO) measurements. The bending angle (BA) anomaly over the Tonga volcanic plume (within 200 km of the eruption center) at 5:17 UTC on 15 January showed a prominent peak at higher stratospheric heights. The top of the BA anomaly revealed that negative to positive change occurred at ~38 km, indicating the first height where the RO line-of-sight encountered the volcanic plume. The BA anomaly further revealed an increase of ~50% at ~36.1 km, and confirmed that the volcanic plume reached above ~36 km. Furthermore, the evolution of BA perturbations within 24 h after the initial explosion is also discussed herein. From collocated RO profiles with the volcanic plume, we can find a clear descent of the peak altitude of the BA perturbation from ~36.1 km to ~29 km within 24 h after the initial eruption. The results from this study will provide some insights into advancing our understanding of volcanic cloud dynamics and their implementation in volcanic plume modeling.

Long-term ion hydration process and lithosphere-atmosphere coupling following the 2021 Fagradalsfjall volcanic eruption using remotely sensed data

After a series of earthquakes, the Reykjanes peninsula in Iceland faced a volcanic eruption for the first time in 800 years. This volcanism of the 2021 Fagradalsfjall started on March 19, 2021, and lasted until September 18, 2021. In this study, the vestiges of the mutual interplay of Earth’s different geophysical shells due to the local lithospheric changes around the Fagradalsfjall were extensively investigated with the help of satellite-based remotely sensed datasets. Firstly, the regional surface deformations caused by the pre-eruption seismic activity are determined using interferometric image pairs, and horizontal and vertical displacement rates are analyzed. Secondly, the satellite observations revealed that the land surface temperature of the entire area increased to a maximum of 40 °C during the maximum phase of lava discharge by the end of May 2021. Moreover, we observed that the surface mass concentrations of SO2 and CO trace gases started to ascend in parallel with the lava discharge after the initial eruption, where their concentrations were doubled in April before reaching their maximum phases (three to four times more than the initial eruption) in May 2021. The cumulative concentrations of the trace gases in the atmosphere emitted from the Fagradalsfjall volcano pushed the regional atmospheric balance into a non-equilibrium state by creating air ionization through various chemical reactions with other atmospheric gases. These ion clusters underwent an ion hydration process that changed the electric conductivity of the atmospheric boundary layer, which covers the first two kilometers of the atmosphere. Finally, our observations showed a sharp decrease in the atmospheric relative humidity that led to an increase in the atmospheric air temperature due to this ion hydration process. The large ion clusters in the atmospheric boundary layer produced a vertical electric field that penetrated over the affected region and brought long-term changes in the ionosphere layer. This unique phenomenon of the simultaneous interaction of different geophysical layers was specifically observed during the maximum phase of the lava discharge and increased ion concentrations in the atmosphere. The used data sets cover the first three months of the volcanism, and this interval seemed to be sufficient to reveal the atmospheric traces. Our comprehensive study provides an important contribution to the theory of the coupling of volcanism and the Earth's atmospheric dynamics.

Mantle source characteristics and magmatic processes during the 2021 La Palma eruption

The 2021 eruption of La Palma (September 19-December 13) was the first subaerial eruption in the Canary Islands in 50 years. Approximately 0.2 km3 of lava erupted from a newly formed, broadly basaltic composite volcanic edifice on the northwestern flank of the Cumbre Vieja volcanic ridge. Comprehensive sampling of the olivine- and clinopyroxene-phyric lavas over the eruption period reveals temporal changes in mineralogy and bulk rock geochemistry from tephrite to basanite. Initial tephrite lavas have low MgO (∼6 wt.%) and elevated TiO2 (∼4 wt.%) and contain amphibole crystals and gabbroic micro-xenoliths. In contrast, lavas with progressively more mafic compositions erupted to approximately day 20 of the eruption and thereafter remained as basanite (∼8 wt.% MgO; 3.7 wt.% TiO2) until eruption termination. Temporal changes in lava chemistry reflect initial eruption of fractionated magmas that crystallized 5-10% olivine and clinopyroxene, as well as minor spinel, sulfide, and magnetite, followed by later eruption of deeper-sourced and more primitive magma. Vanadium-in-olivine oxybarometry indicates parental magmas were oxidized (fO2 = +1.5 to +2 FMQ) with 8.2 ±0.8 wt.% MgO and were generated from between 2.5-3% partial melting of a mantle source potentially containing a pyroxenite component (Xpx = 0.31 ±0.12). Day 1-20 tephrites have more radiogenic 187Os/188Os (0.143-0.148) and lower Pd, Pt, Ir and Os contents than post day 20 basanites (187Os/188Os = 0.141-0.145). Combined with available seismic data, the lavas provide a high-resolution record of eruptive evolution. Initial fractionated tephrite magma was stored in the upper lithosphere up to four years prior to eruption, consistent with pre-cursor seismicity and the presence of partially reacted amphibole and micro-xenoliths. The later lavas of the eruption were fed by more primitive basanitic parental magmas that were likely sourced from the deeper portion of the magma storage system that is underplating the island. Precursor events to the 2021 La Palma eruption involved seismicity and magma emplacement, storage and differentiation, which was followed by mobilisation, eruption, and eventual exhaustion of stored magma and partial melts. This magmatic progression is similar to that documented from the 1949 and 1971 Cumbre Vieja eruptions. Ocean islands with limited basaltic magma supply show similarities to the magmatic evolution observed in large silicic systems, where initial magma emplacement and differentiation is followed by later magma remobilisation that induces volcanic activity.

Hydroacoustic Signals Originating from Marine Volcanic Activity at Kadovar Island, Papua New Guinea, Recorded by the Comprehensive Nuclear-Test-Ban Treaty International Monitoring System

Hydroacoustic signals originating from marine volcanic activity at Kadovar Island (Papua New Guinea), recorded by the Comprehensive Nuclear-Test-Ban Treaty (CTBT) International Monitoring System (IMS) hydroacoustic (HA) station HA11 Wake Island (USA), are examined herein. Episodes of high volcanic activity were identified on two occasions, separated by a period of 1 month. The events studied pertain to an initial eruption series during a period between January and February 2018. Based on local visual observations, the Kadovar volcano began to erupt at the summit and then created a new vent spot near the coast. This series of events also included the collapse of a lava dome. Direction-of-arrival estimates for the hydroacoustic signals detected at HA11 were computed using a cross-correlation technique, which allowed for the discrimination between hydroacoustic signals originating from the Kadovar volcanic activity and numerous other hydroacoustic signals attributed to seismic activity in the Pacific Ocean. The Kadovar-related seismic signals could not be identified by regional IMS seismic stations, suggesting a submarine origin of these events. On the other hand, hydroacoustic signals originating from the Kadovar volcanic activity were identified by the seismometer at Manus Island, which is located between Kadovar and HA11. The study suggests that a series of explosive bursts followed by an unusual rumble and a broadband signal plus rumble may constrain the time of the lava dome collapse event at Kadovar Island to 00:30 UTC, 00:33 UTC, and 00:46 UTC on 09 February 2018. Given the compatibility of this observation with the tsunami generation reported by eyewitnesses on the nearby island of Blup Blup, the authors interpret this particular hydroacoustic signal as being a remote observation of this tsunamigenic event. The objective of this study was to assess the potential added value of IMS hydroacoustic data for remote surveillance of geohazards in otherwise sparsely monitored areas.

Eruption dynamics of Anak Krakatau volcano (Indonesia) estimated using photogrammetric methods

Analyzing video data from an uncrewed aerial vehicle (UAV) of two short-lived dome building events at Anak Krakatau volcano (Indonesia), we determine vertical and horizontal movements of the dome surface prior to explosions, as well as initial eruption velocities and mass eruption rates via automated feature tracking and other photogrammetric methods. Initial eruption velocities and mass eruption rates are estimated as a proxy for eruptive strength. Eruptive strength is found to correlate with deformation magnitude, i.e., larger pre-explosion surface displacements are followed by both higher initial eruption velocities and mass fluxes. In accord with other studies, our observations can be explained by an overpressure underneath the dome’s surface. We assume that the dome seals the underlying vent efficiently, meaning that pre-explosion pressure build-up controls both deformation magnitude and eruptive strength. We support this assumption by a simple numerical model indicating that pre-explosion pressure increases between 8 and 16 MPa. The model further reveals that the two events vary significantly with respect to the importance of lateral visco-elastic flow for pressurization and deformation. The video sequences also show considerable variations in the gas release and associated deformation characteristics. Both constant and accelerating deformation is observed. Our case study demonstrates that photogrammetric methods are suitable to provide quantitative constraints on both effusive and explosive activity. Future work can build on our or similar approaches to develop automated monitoring strategies that would enable the observation and analysis of volcanic activity in near real time during a volcanic crisis.

Mechanism of the Failed Eruption of an Intermediate Solar Filament

Abstract Solar filament eruptions can generate coronal mass ejections (CMEs), which are huge threats to space weather. Thus, we need to understand their underlying mechanisms. Although many authors have studied the mechanisms for several decades, we still do not fully understand in what conditions a filament can erupt to become a CME or not. Previous studies have discussed extensively why a highly twisted and already erupted filament will be interrupted and considered that a strong overlying constraint field seems to be the key factor. However, few of them study filaments in the weak field, namely, quiescent filaments, as it is too hard to reconstruct the magnetic configuration there. Here we show a case study, in which we can fully reconstruct the configuration of an intermediate filament with the MHD-relaxation extrapolation model and discuss its initial eruption and eventual failure. By analyzing the magnetic configuration, we suggest that the reconnection between the erupting magnetic flux rope (MFR) and the overlying field are the key factors that constrained the eruption of the filament. There is observational evidence that MFRs will reconnect with peripheral field lines. Usually, the reconnection between an MFR and peripheral fields will weaken the overlying constraint and promote further eruption, but in some cases in which the magnetic configuration of an MFR is far different from peripheral fields, the reconnection will play a negative role in MFR eruption.

Late Triassic basin inversion of the Qiangtang Basin in northern Tibet: Implications for the closure of the Paleo-Tethys and expansion of the Neo-Tethys

Sedimentologic and tectonic records in the Qiangtang Basin, northern Tibet, indicate a negative basin inversion during the Late Triassic, which reveals Paleo-Tethys closure and Neo-Tethys expansion. In the Triassic sedimentary succession, there is a clear sedimentary facies shift. The Middle Triassic to Carnian (Late Triassic) sequence displays typically shallowing-upward changes related to regional uplift and terrestrial erosion. On the other hand, the Norian (Late Triassic) to Middle Jurassic sequence has typically deepening-upward changes due to the tectonic subsidence and transgression. The negative basin inversion underwent a transition from previous marine environment to terrestrial erosion in the North Qiangtang depression but a terrestrial erosion to marine environment transition in the South Qiangtang depression during the Late Triassic. Elemental data show bimodal volcanic rocks for the Nadi Kangri Formation with intracontinental rift setting. The initial negative inversion started with the Nadi Kangri bimodal volcanic eruption and alluvial/fluvial basal conglomerate that overlapped angular unconformably, disconformably, or conformably on the underlying formations. The U-Pb ages of volcanic samples from the Nadi Kangri Formation range from ∼220 to 201 Ma, and its initial eruption age (∼220 Ma) represents the onset time of negative basin inversion. Our data reveal that the exhumation of northern Qiangtang foreland basin during the early Late Triassic recorded the closure of the Paleo-Tethys Ocean and its branches along the Hoh Xil–Jinshajiang and the Longmu Co–Shuanghu, respectively. The initiation of Qiangtang rifting during the late Late Triassic could be related with the rapid expansion of the Neo-Tethys Ocean along the Bangong–Nujiang.

Evaluating the assimilation of S5P/TROPOMI near real-time SO<sub>2</sub> columns and layer height data into the CAMS integrated forecasting system (CY47R1), based on a case study of the 2019 Raikoke eruption

Abstract. The Copernicus Atmosphere Monitoring Service (CAMS), operated by the European Centre for Medium-Range Weather Forecasts on behalf of the European Commission, provides daily analyses and 5 d forecasts of atmospheric composition, including forecasts of volcanic sulfur dioxide (SO2) in near real time. CAMS currently assimilates total column SO2 products from the GOME-2 instruments on MetOp-B and MetOp-C and the TROPOMI instrument on Sentinel-5P, which give information about the location and strength of volcanic plumes. However, the operational TROPOMI and GOME-2 data do not provide any information about the height of the volcanic plumes, and therefore some prior assumptions need to be made in the CAMS data assimilation system about where to place the resulting SO2 increments in the vertical. In the current operational CAMS configuration, the SO2 increments are placed in the mid-troposphere, around 550 hPa or 5 km. While this gives good results for the majority of volcanic emissions, it will clearly be wrong for eruptions that inject SO2 at very different altitudes, in particular exceptional events where part of the SO2 plume reaches the stratosphere. A new algorithm, developed by the German Aerospace Centre (DLR) for GOME-2 and TROPOMI, optimized in the frame of the ESA-funded Sentinel-5P Innovation–SO2 Layer Height Project, and known as the Full-Physics Inverse Learning Machine (FP_ILM) algorithm, retrieves SO2 layer height from TROPOMI in near real time (NRT) in addition to the SO2 column. CAMS is testing the assimilation of these products, making use of the NRT layer height information to place the SO2 increments at a retrieved altitude. Assimilation tests with the TROPOMI SO2 layer height data for the Raikoke eruption in June 2019 show that the resulting CAMS SO2 plume heights agree better with IASI plume height data than operational CAMS runs without the TROPOMI SO2 layer height information and show that making use of the additional layer height information leads to improved SO2 forecasts. Including the layer height information leads to higher modelled total column SO2 values in better agreement with the satellite observations. However, the plume area and SO2 burden are generally also overestimated in the CAMS analysis when layer height data are used. The main reason for this overestimation is the coarse horizontal resolution used in the minimizations. By assimilating the SO2 layer height data, the CAMS system can predict the overall location of the Raikoke SO2 plume up to 5 d in advance for about 20 d after the initial eruption, which is better than with the operational CAMS configuration (without prior knowledge of the plume height) where the forecast skill is much more reduced for longer forecast lead times.

Burn Lessons Learned From the Whakaari White Island Volcanic Eruption.

New Zealand's most active volcano, Whakaari White Island was a common tourist attraction prior to its eruption on December 9, 2019. At the time of the eruption, there were 47 people on the island from 3 tour groups. Thirty-nine people survived the initial eruption and were extracted. Thirty-one entered into the New Zealand National Burn Service across four hospitals. The median age of the patients treated at the National Burn Centre was 45.5 years (range: 14-67 years) and median TBSA burn was 49.5% (range: 9%-90%). The 3-month survival of this eruptive event was 55%, which subsequently fell to an overall rate of 53% following one late death of an early survivor after repatriation home. Of the patients who survived the initial eruption for long enough to be admitted to the National Burn Service, the overall survival rate was 71% at 3 months. We describe 12 lessons we have learnt from our management of the survivors. The key surgical lessons among these are: 1) The injuring mechanism combined ballistic trauma, thermal and acidic burn components, with the acid component being the most problematic and urgent for management; 2) Volcanic ash burns result in ongoing burn depth progression, deep underlying tissue damage and significant metabolic instability; 3) Early skin grafting was not successful in many cases; 4) Reconstructive strategy needed adjusting to cope with the high operative demand and limited donor sites in all patients; 5) Protect yourself from potential dangers with additional personal protective equipment in an unfamiliar setting.

Day-to-day variability of upper troposphere and lower stratosphere temperature in response to Taal volcanic eruption inferred from COSMIC-2 RO measurements

For the first time after 43 years of its previous eruption in 1977, the Taal volcano in the Philippines (14°N, 120°.59E) erupted in the afternoon of 12 January 2020. Due to the strong anticyclonic circulation in the upper troposphere (~150 hPa), the resultant volcanic ash and sulfur dioxide (SO2) were transported to the downwind tropical central Pacific Ocean within a few days after the initial eruption. In this study, day-to-day variability of upper troposphere lower stratosphere (UTLS) temperature in response to the Taal volcanic eruption event over the source region (±5o latitude and longitude around the volcano) and the downwind Pacific region (10-20oN, 160-180°E) is delineated by using the recently launched Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC)-2 radio occultation (RO) data. The daily mean temperature over the source and downwind regions were compared with the background long-term January mean temperature (obtained from 2007 to 2019 COSMIC-1 RO data) over the respective regions. Significant positive temperature anomalies in the lower stratosphere are evident over the source (between 12 and 14 January) and downwind (between 14 and 19 January) regions after the eruption. These positive anomalies may be due to the association of absorption and local radiative heating by volcanic aerosols. The Ozone Monitoring Instrument (OMI) measurements clearly show the presence of SO2 in the UTLS region. The presence of sulfate aerosols in the UTLS region a few days after eruption is also supported by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) images. Furthermore, we also describe the temperature structure near the volcano and away from the volcano and found a quite different structure in the UTLS region. A significant temperature inversion at ~15 km altitude is evident near the volcano, whereas it is noticed at ~16 km away from the volcano. In conclusion, in line with the previous studies, the present study provides further insights to the UTLS temperature in response to volcanic eruptions.

Using GIS to Create Hazard Maps and Assess Evacuation Routes around “The Gate to Hell”; Masaya Volcano, Nicaragua

Volcán Masaya in Nicaragua is made of a series of calderas and craters that lies 7 km from the city of Masaya with a population of over 100,000. Masaya is part of the Central American Volcanic Arc (CAVA) which contains hundreds of volcanoes. While many of the volcanoes of the arc produce small, quiescent eruptions, some are capable of large explosive events. The recent cycle of volcanism at Masaya began 7000 years ago. Initial eruptions were primarily lava, small ash flows, ashfalls, and degassing events which eventually gave way to climactic Vulcanian eruptions. The hazards presented from this system affect not only larger cities, but many underdeveloped communities surrounding Volcán Masaya. These communities require a simple map and action plan to use during an evacuation. While government-issued routes are in place, there are no known secondary options. The communities surrounding Masaya lack the education they need for having such a fierce geologic feature right in their backyard to base their own opinions on when and if to evacuate the area on their own accord. We visited the study area to gather data for the creation of an evacuation route and hazard map to help prepare the surrounding communities. By consolidating our research and field data, the maps we created give the communities surrounding Masaya more insight as to the behavior of the eruptions. This research gives the local population options for evacuation and more knowledge about their environment.

Post-eruption evolution of maar lakes and potential instability: The Lake Pavin case study, French Massif Central

Few studies have focused on the post-eruption evolution of maar craters and associated lake level changes, although breaching of the crater rim poses mass-flow and flood hazards long after the initial eruption. Lake Pavin is a maar lake in the French Massif central formed by an eruption c. 6700 years ago. The maar is perched on the edge of a glacially-shaped valley and the rim overlooks the surrounding subdued landscape. The rim is breached to the north by an overflow channel, and to the south the maar has cut into the flank of the Montchal scoria cone and lava flows. Incision of the lake outlet led to the growth of an alluvial fan that pushed the Couze Pavin River towards the north side of the Gelat valley.Two lake terraces within the crater are used to determine stages in the evolution of the lake. The highstand Stage 1 terrace +18 m above the current lake level indicates that the post-eruption lake surface and volume was 15% and 38% larger than the present-day lake, respectively, prior to the 5-7th Century CE. The poorly preserved Stage 2 bench, +4.35 m on the west side of the natural dam, indicates that incision paused between Stage 1 and achievement of present lake level (Stage 3) before the 18th Century. Four units of streamflow deposits (c. 0.087 km2 in area and 0.14–0.18 km3 in volume) that formed the fan at the mouth of the outlet in the Gelat valley have been 14C dated to between the 9th and 16th Century. From the fan sedimentology, we infer that the lake level dropped slowly between highstand Stages 1 and 2, when the outlet cut down through the rim saddle. The lake level drop accelerated between Stage 2 and Stage 3 before the 14th Century, inducing small debris flows. The latter may have resulted from heavy rainstorms, but there is no evidence for catastrophic events. Stepwise downcutting of the north rim saddle was also governed by contrasted properties of the deposits forming the dam. The current lake level has been stable since at least the early 18th Century, but the long-term stability of the dam is at risk.

Cetuximab Induced Hidrocystomas: A Case Report

Cetuximab is an epidermal growth factor receptor (EGFR) inhibitor that commonly results in follicular-based acneiform eruptions. EGFR is expressed in the epidermis, hair follicle epithelium, sweat gland apparatus, and plays an important role in the differentiation and development of the hair follicle. In this report we describe a 70-year-old man who developed an acneiform eruption on his nose, cheeks, neck, and back when cetuximab was started for metastatic colorectal carcinoma. This initial eruption improved with cessation of cetuximab but left residual cystic papules on his nose and multiple superficial white cysts on his bilateral cheeks, neck and back. Skin biopsy of a representative lesion on the nose revealed a cyst-like cavity lined with epithelium similar to sweat glands within the dermis consistent with a hidrocystoma. In this case, it is plausible that the use of an EGFR inhibitor resulted in a cutaneous inflammatory reaction, that subsequently healed with blockage of the sweat duct apparatus causing the formation of cutaneous cysts, including both hidrocystomas and milia. Alternatively, the blockage of the duct may have resulted from inhibition of basal cell migration and increased cell adhesion within the eccrine gland causing accumulation of eccrine gland secretion, and eventually hidrocystomas. To our knowledge, this is the first case describing the resolution of a typical cetuximab-induced acneiform eruption with residual hidrocystomas and milia.

Geomorphology and tephrochronology review of the Hasandağ volcano (southern Cappadocia, Turkey)

This research proposes a suite of volcanic events that took part in the edification of the double-peaked Hasandag stratovolcano in southern Cappadocia. Inter-correlations of sections dispatched along geographic transects across the volcano evidence continuities/discontinuities and stratigraphic relationships using key layers identified through this process which is, later, framed by a radiometric dating control of some of these formations. The main goal is to provide some chronological markers of the geomorphological evolution of the volcano. The stratigraphy, lithology and facies, the landform definitions and new dates provide information about eruption types and their role in shaping the morphologies of the volcano through time. Recent ages from literature and seven new K/Ar dates contribute in enriching the story of the volcanic activity that built the Hasandag stratovolcano landforms. The part of the story exposed in this article starts mainly c. 700/650 ka ago with the construction of a Mid-Pleistocene volcano. Later, between 220 and 120 ka ago, main events occurred in the NE part of the volcano. After an initial Plinian eruption, a caldera collapse is recorded by pumice flows. Close to the emission point, a small collapse structure is today filled with a much younger dacite flow. After the Plinian eruption, the partial destruction of a volcano caused one or two avalanches containing several meters-thick distinct blocks that flew north c. 16–18 km over the roof of the Cappadocian Miocene ignimbrites. Remains of the destructed volcano flanks are not visible. Either they are buried below younger lava flows forming the Kucuk Hasandag cone, or a seism in the Tuz Golu Fault Zone during the avalanche may have resulted in an explosion. This event was followed by extrusion of rhyolitic domes positioned on the caldera rim, emitting pumice falls now filling-in the Guvercin valley stream down to Ihlara village. During Late Pleistocene emission of andesite and dacite flows and domes, accompanied by several pyroclastic flows formed today’s terminal cones of the stratovolcano.