scholarly journals Complex hazard cascade culminating in the Anak Krakatau sector collapse

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Thomas R. Walter ◽  
Mahmud Haghshenas Haghighi ◽  
Felix M. Schneider ◽  
Diego Coppola ◽  
Mahdi Motagh ◽  
...  
Keyword(s):  
Early Detection ◽  
Surface Area ◽  
Seismic Signals ◽  
Sector Collapse ◽  
Small Earthquake ◽  
Thermal Anomalies ◽  
Volcanic Islands ◽  
Krakatau Volcano ◽  
State Of Activity

Abstract Flank instability and sector collapses, which pose major threats, are common on volcanic islands. On 22 Dec 2018, a sector collapse event occurred at Anak Krakatau volcano in the Sunda Strait, triggering a deadly tsunami. Here we use multiparametric ground-based and space-borne data to show that prior to its collapse, the volcano exhibited an elevated state of activity, including precursory thermal anomalies, an increase in the island’s surface area, and a gradual seaward motion of its southwestern flank on a dipping décollement. Two minutes after a small earthquake, seismic signals characterize the collapse of the volcano’s flank at 13:55 UTC. This sector collapse decapitated the cone-shaped edifice and triggered a tsunami that caused 430 fatalities. We discuss the nature of the precursor processes underpinning the collapse that culminated in a complex hazard cascade with important implications for the early detection of potential flank instability at other volcanoes.

Precursors and processes culminating in the Anak Krakatau December 2018 sector collapse and tsunami

2020 ◽  
Author(s):  
Thomas R. Walter ◽  
Keyword(s):  
Volcanic Eruptions ◽  
Early Warning Systems ◽  
Ground Movement ◽  
Island Growth ◽  
Sector Collapse ◽  
Tsunami Waves ◽  
Thermal Anomalies ◽  
Tsunami Disaster ◽  
Intense Activity ◽  
Krakatau Volcano

<p>It is 135 years after the 1883 volcano-triggered tsunami disaster, when Krakatau volcano became once more the source of a deadly tsunami striking without warning. We use data recorded on the ground and by satellite, to show that the volcano was in an elevated stage of activity throughout the year 2018, producing thermal anomalies associated with volcanic deposits, an increase of the island area and ground movement of the southwestern sector of the island towards the sea, increasing in June 2018. Following further intense activity on 22 December 2018, seismic data reveal the timing and duration when this sector collapsed. The landslide removed 102 million m³ of material subaerially, which was followed by ~15 minutes of phreatic explosions. This study allows better understanding of the complex hazard cascades, including precursory thermal anomalies, island growth and deformation, followed by sector collapse, tsunami waves, and finally explosive volcanic eruptions, and has important implications for designing early warning systems.</p>

scholarly journals Effectiveness of distributed temperature measurements for early detection of piping in river embankments

2017 ◽  
Author(s):  
Silvia Bersan ◽  
André R. Koelewijn ◽  
Paolo Simonini
Keyword(s):  
Early Detection ◽  
Large Scale ◽  
Thermal Response ◽  
Temperature Data ◽  
Internal Erosion ◽  
Monitoring Systems ◽  
Distributed Temperature Sensing ◽  
Thermal Anomalies ◽  
The Past ◽  
Backward Erosion Piping

Abstract. Internal erosion is the cause of a significant percentage of failure and incidents involving both dams and river embankments in many countries. In the past 20 years the use of fibre-optic Distributed Temperature Sensing (DTS) in dams has proved to be an effective tool for detection of leakages and internal erosion. This work investigates the effectiveness of DTS for dike monitoring, focusing on early detection of backward erosion piping, a mechanism that affects the foundation layer of structures resting on permeable, sandy soils. The paper presents data from a piping test performed on a large-scale experimental dike equipped with a DTS system together with a large number of accompanying sensors. The effect of seepage and piping on the temperature field is analysed, eventually identifying the processes that cause the onset of thermal anomalies around piping channels and thus enable their early detection. Making use of dimensional analysis, the factors that influence that thermal response of a dike foundation are identified. Eventually some tools are provided that can be helpful for the design of monitoring systems and for interpretation of temperature data.

scholarly journals Sticky traps as an early detection tool for crawlers of Adelges tsugae (Hemiptera: Adelgidae)

2019 ◽  
Author(s):  
Jeffrey G Fidgen ◽  
Mark C Whitmore ◽  
Kala D Studens ◽  
Chris J K Macquarrie ◽  
Jean J Turgeon
Keyword(s):  
Early Detection ◽  
Surface Area ◽  
Detection Rate ◽  
Hemlock Woolly Adelgid ◽  
Adelges Tsugae ◽  
Sticky Trap ◽  
Peak Activity ◽  
First Instar ◽  
Detection Tool ◽  
Set Up

Abstract We developed an approach using sticky trap arrays as an early detection tool for populations of first-instar nymphs of the hemlock woolly adelgid (Adelges tsugae Annand), a pest of hemlocks (Tsuga spp. [Pinaceae]) in North America. We considered the detection rate of at least one nymph from trapping arrays consisting of one to six sticky panels, where we varied both the surface area of each trap that we assessed and the length of the trapping duration. We also estimated the time needed to set up, service, and assess groups of traps and attempted to relate capture of nymphs on traps to incidence and abundance of A. tsugae in the canopy above the traps. Arrays consisting of two traps provided a detection rate of 75% when 87.5% of the surface area of each trap was assessed, a process that required 38 min per array. The probability of detecting nymphs on traps left in the field for 5–6 d was similar to that for traps left for 12 d. The number of nymphs trapped in an array predicted the probability of finding A. tsugae in the canopy but only when all six traps were fully assessed. To reliably detect incipient A. tsugae infestations, we recommend placing arrays of traps at 1 km intervals along the perimeter of a stand during peak activity of first-instar sistentes nymphs and servicing these arrays every 5–7 d.

Quantifying surface-area changes of volcanic islands driven by Pleistocene sea-level cycles: biogeographical implications for the Macaronesian archipelagos

2014 ◽  
Vol 41 (7) ◽  
pp. 1242-1254 ◽  
Author(s):  
Kenneth F. Rijsdijk ◽  
Tom Hengl ◽  
Sietze J. Norder ◽  
Rüdiger Otto ◽  
Brent C. Emerson ◽  
...  
Keyword(s):  
Sea Level ◽  
Surface Area ◽  
Volcanic Islands

scholarly journals Thermal Anomalies Detection Using Comparative Method for Small Earthquake

2018 ◽  
Vol 186 ◽  
pp. 01008
Author(s):  
Pisanu Wongpornchai ◽  
Chanida Suwanprasit
Keyword(s):  
Land Surface ◽  
Plate Tectonics ◽  
Comparative Method ◽  
Thermal Anomaly ◽  
Earthquake Precursor ◽  
Small Earthquake ◽  
Thermal Anomalies ◽  
Before And After ◽  
Thermal Region ◽  
The Relationship

Thermal anomaly is one of the earthquake precursor in the earthquake preparatory phase. Remote sensing in thermal region has been employed based on the concept of stress accumulation in the active plate tectonics region, which may be transformed as temperature variation prior to earthquake. MODIS Land Surface Temperature has been commonly used to locate the thermal anomalies before the earthquake. Recently researches have been focusing on moderate or large magnitude earthquake events. In Thailand, small earthquake can severely damage the unprepared area. This study, the daily day- and nighttime data of MODIS MOD11A1 product for 30 days before and 15 days after the earthquake on April 22, 2007, in Wiang Pa Pao District, Chiang Rai Province, Thailand, were processed and analysed to locate possibility of thermal anomalies. Thermal anomalies before and after the earthquakes were detected using the comparative method. The result found that the thermal anomaly temperature could be high up to 4.1 - 10.9 C which occurred in 21 - 22 days prior to the earthquake. Therefore, it may conclude that small earthquake can also release energy as the detectable thermal anomaly. However, more study about the relationship between thermal precursor and earthquake is needed to continue.

scholarly journals Effectiveness of distributed temperature measurements for early detection of piping in river embankments

2018 ◽  
Vol 22 (2) ◽  
pp. 1491-1508 ◽  
Author(s):  
Silvia Bersan ◽  
André R. Koelewijn ◽  
Paolo Simonini
Keyword(s):  
Early Detection ◽  
Large Scale ◽  
Thermal Response ◽  
Temperature Data ◽  
Internal Erosion ◽  
Monitoring Systems ◽  
Distributed Temperature Sensing ◽  
Thermal Anomalies ◽  
The Past ◽  
Backward Erosion Piping

Abstract. Internal erosion is the cause of a significant percentage of failure and incidents involving both dams and river embankments in many countries. In the past 20 years the use of fibre-optic Distributed Temperature Sensing (DTS) in dams has proved to be an effective tool for the detection of leakages and internal erosion. This work investigates the effectiveness of DTS for dike monitoring, focusing on the early detection of backward erosion piping, a mechanism that affects the foundation layer of structures resting on permeable, sandy soils. The paper presents data from a piping test performed on a large-scale experimental dike equipped with a DTS system together with a large number of accompanying sensors. The effect of seepage and piping on the temperature field is analysed, eventually identifying the processes that cause the onset of thermal anomalies around piping channels and thus enable their early detection. Making use of dimensional analysis, the factors that influence this thermal response of a dike foundation are identified. Finally some tools are provided that can be helpful for the design of monitoring systems and for the interpretation of temperature data.

Pinocytotic-Like Forms of Mitochondria From Rat Anterior Pituitary

1968 ◽  
Vol 26 ◽  
pp. 146-147
Author(s):  
Burton B. Silver
Keyword(s):  
Electron Micrographs ◽  
Conformational Changes ◽  
Anterior Pituitary ◽  
Dynamic State ◽  
Surrounding Cell ◽  
The Matrix ◽  
The Moment ◽  
Cell Medium ◽  
Sectioned Tissue ◽  
State Of Activity

Sectioned tissue rarely indicates evidence of what is probably a highly dynamic state of activity in mitochondria which have been reported to undergo a variety of movements such as streaming, divisions and coalescence. Recently, mitochondria from the rat anterior pituitary have been fixed in a variety of configurations which suggest that conformational changes were occurring at the moment of fixation. Pinocytotic-like vacuoles which may be taking in or expelling materials from the surrounding cell medium, appear to be forming in some of the mitochondria. In some cases, pores extend into the matrix of the mitochondria. In other forms, the remains of what seems to be pinched off vacuoles are evident in the mitochondrial interior. Dense materials, resembling secretory droplets, appear at the junction of the pores and the cytoplasm. The droplets are similar to the secretory materials commonly identified in electron micrographs of the anterior pituitary.

Preparation and characterisation of vanadium pentoxide supported rhodium catalyst

1988 ◽  
Vol 46 ◽  
pp. 946-947
Author(s):  
A. Legrouri
Keyword(s):  
Aqueous Solution ◽  
Thermal Decomposition ◽  
Physicochemical Properties ◽  
Surface Area ◽  
Vanadium Pentoxide ◽  
High Purity ◽  
Gas Adsorption ◽  
Rhodium Catalyst ◽  
Optical Methods ◽  
Reducible Oxides

The industrial importance of metal catalysts supported on reducible oxides has stimulated considerable interest during the last few years. This presentation reports on the study of the physicochemical properties of metallic rhodium supported on vanadium pentoxide (Rh/V2O5). Electron optical methods, in conjunction with other techniques, were used to characterise the catalyst before its use in the hydrogenolysis of butane; a reaction for which Rh metal is known to be among the most active catalysts.V2O5 powder was prepared by thermal decomposition of high purity ammonium metavanadate in air at 400 °C for 2 hours. Previous studies of the microstructure of this compound, by HREM, SEM and gas adsorption, showed it to be non— porous with a very low surface area of 6m2/g3. The metal loading of the catalyst used was lwt%Rh on V2Q5. It was prepared by wet impregnating the support with an aqueous solution of RhCI3.3H2O.

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