Muographic monitoring of hydrogeomorphic changes induced by post-eruptive lahars and erosion of Sakurajima volcano

Post-eruptive destabilization of volcanic edifices by gravity driven debris flows or erosion can catastrophically impact the landscapes, economies and human societies surrounding active volcanoes. In this work, we propose cosmic-ray muon imaging (muography) as a tool for the remote monitoring of hydrogeomorphic responses to volcano landscape disturbances. We conducted the muographic monitoring of Sakurajima volcano, Kyushu, Japan and measured continuous post-eruptive activity with over 30 lahars per year. The sensitive surface area of the Multi-Wire-Proportional-Chamber-based Muography Observation System was upgraded to 7.67 m 2 ; this made it possible for the density of tephra within the crater region to be measured in 40 days. We observed the muon flux decrease from 10 to 40% through the different regions of the crater from September 2019 to October 2020 due to the continuous deposition of tephra fallouts. In spite of the long-term mass increase, significant mass decreases were also observed after the onsets of rain-triggered lahars that induced the erosion of sedimented tephra. The first muographic observation of these post-eruptive phenomena demonstrate that this passive imaging technique has the potential to contribute to the assessment of indirect volcanic hazard

Improvement of cosmic-ray muography for Earth sciences and civil engineering

Muography is utilizing the cosmic-ray muons to deduce the amount of material across large-sized objects, similarly to X-raying of human body. We specifically developed Multi-Wire Proportional Chamber (MWPC)-based tracking systems with high (> 98 %) efficiency, fair (< 10 mrad) angular resolution and low (< 6 W) power for Earth sciences and civil engineering. A muography observatory is assembled from trackers on a sensitive surface of 5.5 m 2 at 2.8 km distance in South-West from Sakurajima volcano to provide projective density images of the crater regions for future measurements of mass variations occurred during eruptions. An industrial applicability of portable, MWPC-based instruments have been demonstrated with the muographic imaging of an underground iron pillar. We investigated the limits of muography: the Gaisser model is suggested to be modified with an energy exponent of -2.64 and constant scale factor of 0.66 for imaging in near-horizontal directions after large (> 1,000 m.s.r.e.) thicknesses. The multiple scattering of muons across the targeted object is limiting the imaging resolution from 10 mrad to 5 mrad with the increase of thickness between 50 m.s.r.e. and 2,000 m.s.r.e.. The precise measurement of low-energy muon spectra is required to improve muography of small-sized objects. We developed a 5-meter-length, rotatable, MWPC-based spectrometer to precisely measure the energy spectra of muons between 0.5 GeV and 5 GeV from vertical to horizontal directions. It is a consecutive series of thirteen detectors with a positional resolution of approx. 4 mm and lead plates. The spectrometer and the first results are presented

Muography of the active Sakurajima volcano: recent results and future perspectives of hazard assessment

Sakurajima volcano is one of the world’s most active volcanoes with over 3,000 of explosive eruptions during the last five years. A muography observatory is under construction in international collaboration since 2017 at a distance of approx. 2,800 m in south-west direction from the active craters. Currently, the Sakurajima Muography Observatory is operating with 11 Multi-Wire-Proportional-Chamber-based Muography Observation Systems that are covering a sensitive surface area of 8.25 square meters. This work is focusing on the volcanological implications of muographic monitoring of Sakurajima: (i) tephra deposition, and erosion of the surface region exist due to heavy rains and post-eruptive lahars; (ii) magmatic plug formation was observed beneath the active craters after the deactivation of Showa crater in 2018 and after a dormant period of Central craters in 2020; (iii) machine-learning-based processing of daily muographic images achieved a fair area under the receiver operating characteristic curve score of 0.76

Gaseous Tracking Detectors at the Sakurajima Muography Observatory

Muography is a novel imaging technology to reveal density structure of hill-sized objects. The cosmic muons predictably lose their energy and penetrate hundreds of meters into the ground, thus their differential local flux correlates with the crossed density-length. The Sakurajima Muography Observatory in Kagoshima, Japan, is the largest muography experiment targeting an active volcano. A set of multilayered gaseous detectors are used to reconstruct the muon tracks, thus by measuring the flux, imaging of the inner part of the volcano become possible. The paper focuses on the technical challenges of such a particle tracking system, the designed multi-wire proportional chambers, and the recent results from the measurements

Földtudományi kutatások és geotechnikai alkalmazások kozmikus müonok mérésével

A kozmikus eredetű müon elemi részecskék a felső légkörből eljutnak a Föld felszínére, és akár több kilométeres mélységre is behatolnak a kéregbe. A müonok detektálásával feltérképezhető az általuk áthatolt szilárd, folyékony és lég nemű közeg sűrűségeloszlása hasonlóan a röntgen-radiográfi ához. A kozmikus müonok detektálásán alapuló, passzív és roncsolásmentes képalkotási eljárást müográfi ának nevezzük. Ez az újszerű képalkotási technika hozzájárulhat geológiai szerkezet feltárásához, a geofi zikai folyamatok jobb megértéséhez, a természeti veszélyek előrejelzéséhez és különböző geotechnikai alkalmazásokhoz

Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.

BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362

Igneous processes in the small bodies of the Solar System I. Asteroids and comets

Summary: Igneous processes were quite widespread in the small bodies of the Solar System (SBSS) and were initially fueled by short-lived radioisotopes, the proto-Sun, impact heating, and differentiation heating. Once they finished, long-lived radioisotopes continued to warm the active bodies of the Earth, (possibly) Venus, and the cryovolcanism of Enceladus.The widespread presence of olivine and pyroxenes in planets and also in SBSS suggests that they were not necessarily the product of igneous processes and they might have been recycled from previous nebular processes or entrained in comets from interstellar space. The difference in temperature between the inner and the outer Solar System has clearly favored thermal annealing of the olivine close to the proto-Sun. Transport of olivine within the Solar System probably occurred also due to protostellar jets and winds but the entrainment in SBSS from interstellar space would overcome the requirement of initial turbulent regime in the protoplanetary nebula