Charge structure in volcanic plumes: a comparison of plume properties predicted by an integral plume model to observations of volcanic lightning during the 2010 eruption of Eyjafjallajökull, Iceland

Observations of volcanic lightning made using a lightning mapping array during the 2010 eruption of Eyjafjallajökull allow the trajectory and growth of the volcanic plume to be determined. The lightning observations are compared with predictions of an integral model of volcanic plumes that includes descriptions of the interaction with wind and the effects of moisture. We show that the trajectory predicted by the integral model closely matches the observational data and the model well describes the growth of the plume downwind of the vent. Analysis of the lightning signals reveals information on the dominant charge structure within the volcanic plume. During the Eyjafjallajökull eruption both monopole and dipole charge structures were observed in the plume. By using the integral plume model, we propose the varying charge structure is connected to the availability of condensed water and low temperatures at high altitudes in the plume, suggesting ice formation may have contributed to the generation of a dipole charge structure via thunderstorm-style ice-based charging mechanisms, though overall this charging mechanism is believed to have had only a weak influence on the production of lightning

Using Lightning Observations as a Volcanic Eruption Monitoring Tool

Lightning commonly occurs in the eruption columns produced by explosive volcanic eruptions. There are several different kinds of lightning detection instruments that could be employed to help monitor volcanoes, each with their own advantages and disadvantages. Very low frequency (VLF) instruments have the ability to detect lightning at long ranges but tend to have low sensitivity due to network geometry and typically can provide only the time and 2-D location of a cloud-to-ground return stroke or similar high-amplitude pulse produced by an intracloud discharge. Low frequency (LF) and medium frequency (MF) instruments typically have more sensitivity than a VLF network but can only be used for detection on a regional scale. Very high frequency (VHF) lightning mapping instruments also provide only regional coverage but detect all lightning within their range. During the 2009 eruption of Redoubt Volcano, Alaska, USA, each of these types of instruments detected lightning from Redoubt’s ash plume. The VHF system consistently detected lightning before the other two during each distinct explosive event and also detected more lightning than the others, by one or two orders of magnitude. Lightning observations could be used to confirm, and in some cases, detect explosive volcanic activity. The rapid response provided by lightning monitoring is a valuable tool for fast identification of potentially hazardous ash clouds

Spectacular Lightning Revealed in 2009 Mount Redoubt Eruption

The explosive eruption of Alaska\u27s Mount Redoubt volcano in March and April 2009 provided a superb opportunity for studying volcanic lightning. The energetic explosions produced powerful volcanic lightning storms, the largest of which rivaled the intensity of the massive supercell thunderstorms that frequent the midwestern Great Plains. Although lightning often has been observed in the plumes of explosive volcanic eruptions, only a handful of detailed studies have delved into the origins of volcanic lightning. Active volcanoes tend to be situated in remote locations, where they are difficult to observe, and often have sudden, unpredicted eruptions. Even when the eruptions are observed close at hand, the volcanic clouds are intensely opaque, obscuring most of the lightning from view

Autosomal recessive cutis laxa type Ib—Successful redo aortic root and arch replacement

Abstract We present an adolescent girl with a highly stenotic ascending aortic conduit of her former during infancy corrected giant aneurysm. Genetic testing determined autosomal recessive cutis laxa type‐Ib as the underlying connective tissue disorder. Re‐do valve sparing root and arch replacement gained excellent restoration of the aorta; 1‐year‐follow‐up was uneventful

Examining the Statistical Relationships between Volcanic Seismic, Infrasound, and Electrical Signals: A Case Study of Sakurajima Volcano, 2015

Sakurajima volcano in Japan is known for frequent eruptions containing prolific volcanic lightning. Previous studies from eruptions at Redoubt have shown preliminary correlations between seismic, infrasound, and radio frequency signals. This study uses field data collected at Sakurajima from 28 May–7 June 2015 and multivariable statistical modeling to quantify these relationships. We build regression equations to examine each of the following parameters of electrical activity: (1) the presence of electrical activity, (2) the presence of the radio frequency signal called continual radio frequency impulses (CRF), (3) the presence of lightning, (4) the overall duration of electrical activity, and (5) the total number of radio frequency sources located by a lightning mapping array. We model these response variables against: (1) seismic energy, (2) infrasound energy, (3) seismic duration, (4) infrasound duration, and (5) the volcano acoustic seismic ratio. Our final regression equations show that each parameter of electrical activity is best defined by a separate set of response parameters, but overall events with greater explosivity correlate with higher amounts of electrical activity. Specifically, (1) the probability of CRF occurring, and the overall number of located radio frequency sources are likely related to deeper fragmentation depths; (2) the probability of electrical activity occurring at all, and specifically the probability of lightning being generated are correlated with high infrasound energies indicating that the gas thrust phase of plume formation plays an important role in charge generation; and (3) the longer an eruption (as determined by the duration of the infrasound signal) the longer we can expect to see radio frequency signals generated

The Relationships Between Plume Dynamics and Volcanic Electrification as Measured by a Lightning Mapping Array: a Case Study of Sakurajima Volcano, 2015

The role of volcanic lightning in plume monitoring and hazard mitigation has increased in recent years. Development of the high-definition lightning mapping array (LMA) and recent advancements in video analysis have allowed us to examine the relationships between detailed lightning statistics and plume measurements. In this work we describe the results of a case study of Sakurajima Volcano in 2015. Over 200 events were recorded using both the Lightning Mapping Array and a FLIR camera. By applying an optical-flow algorithm to the FLIR data we created Rise-diagrams (which give insight on initial velocity and maximum plume height) and Tacho-diagrams (which allow us to calculate the initial velocity of the plume, the peak flux rate, and the cumulative volume of the plume). We take a detailed look at the relationships between the plume dynamics derived from these diagrams and the type and amount of volcanic electrification. We use multi-variable logistic and linear statistical regressions to determine the probability relationships for the occurrence of volcanic electrification and to calculate the scaling relationship between the amount of electrification and the measured plume parameter

Examining the Statistical Relationships between Volcanic Seismic, Infrasound, and Electrical Signals: A Case Study of Sakurajima Volcano, 2015

Sakurajima volcano in Japan is known for frequent eruptions containing prolific volcanic lightning. Previous studies from eruptions at Redoubt have shown preliminary correlations between seismic, infrasound, and radio frequency signals. This study uses field data collected at Sakurajima from 28 May–7 June 2015 and multivariable statistical modeling to quantify these relationships. We build regression equations to examine each of the following parameters of electrical activity: (1) the presence of electrical activity, (2) the presence of the radio frequency signal called continual radio frequency impulses (CRF), (3) the presence of lightning, (4) the overall duration of electrical activity, and (5) the total number of radio frequency sources located by a lightning mapping array. We model these response variables against: (1) seismic energy, (2) infrasound energy, (3) seismic duration, (4) infrasound duration, and (5) the volcano acoustic seismic ratio. Our final regression equations show that each parameter of electrical activity is best defined by a separate set of response parameters, but overall events with greater explosivity correlate with higher amounts of electrical activity. Specifically, (1) the probability of CRF occurring, and the overall number of located radio frequency sources are likely related to deeper fragmentation depths; (2) the probability of electrical activity occurring at all, and specifically the probability of lightning being generated are correlated with high infrasound energies indicating that the gas thrust phase of plume formation plays an important role in charge generation; and (3) the longer an eruption (as determined by the duration of the infrasound signal) the longer we can expect to see radio frequency signals generated

Volcanic Lightning as an Indicator of Ash Parameters: A Case Study of Sakurajima Volcano, Japan, May-June 2015

Volcanic lightning is an emerging field of study for monitoring explosive, ashproducing eruptions. Volcanic ash is hazardous to aviation as well as local communities. Using volcanic lightning to monitor ongoing ash emissions, however, requires a better understanding of how volcanic lightning develops, and whether or not lightning can be used as an indicator for specific ash characteristics. Volcanic lightning is common at Sakurajima Volcano, Japan. During the summer of 2015 we deployed a 9 station Lightning Mapping Array (LMA), developed by New Mexico Institute of Mining and Technology, within 20 km of Sakurajima Volcano to detect the very high-frequency electromagnetic radiation generated by volcanic lightning. Of the eruptions analyzed so far the two main types of electrical signals recorded were near vent-lightning and continuous radio frequencies (CRF). In addition to the LMA data we collected samples of actively falling ash during a tenday observation period from May 29th-June 7th 2015. Eruptive events were also recorded on a Trillium broadband three-component seismometer. Ash samples were characterized in terms of componentry, plagioclase microlite number density, laser diffraction particle size analysis, and particle morphology using a PharmaVision 830. The ash parameters were compared with maximum vertical seismic amplitudes and the electrical discharge statistics of the respective explosive events. We have begun to determine the relationships that exist between quantifiable ash characteristics and volcanic electrification, especially the occurrence of CRF. We have found that CRF occurred during events where ash samples were composed of greater than 60% glass with less than 10% lithics. CRF was also present during eruptions whose samples have have high mean roundness but maintain a distribution tail of acicular grains. Finally, CRF occurred in more explosive events as defined by higher seismic amplitudes (\u3e7um). We infer from these relationships that CRF is generated in highly explosive events by a combination of initial and secondary fragmentation of the ash as it is generated and travels up the conduit

Volcanic Lightning as an Indicator of Ash Parameters: A Case Study of Sakurajima Volcano, Japan, May-June 2015

Volcanic lightning is an emerging field of study for monitoring explosive, ashproducing eruptions. Volcanic ash is hazardous to aviation as well as local communities. Using volcanic lightning to monitor ongoing ash emissions, however, requires a better understanding of how volcanic lightning develops, and whether or not lightning can be used as an indicator for specific ash characteristics. Volcanic lightning is common at Sakurajima Volcano, Japan. During the summer of 2015 we deployed a 9 station Lightning Mapping Array (LMA), developed by New Mexico Institute of Mining and Technology, within 20 km of Sakurajima Volcano to detect the very high-frequency electromagnetic radiation generated by volcanic lightning. Of the eruptions analyzed so far the two main types of electrical signals recorded were near vent-lightning and continuous radio frequencies (CRF). In addition to the LMA data we collected samples of actively falling ash during a tenday observation period from May 29th-June 7th 2015. Eruptive events were also recorded on a Trillium broadband three-component seismometer. Ash samples were characterized in terms of componentry, plagioclase microlite number density, laser diffraction particle size analysis, and particle morphology using a PharmaVision 830. The ash parameters were compared with maximum vertical seismic amplitudes and the electrical discharge statistics of the respective explosive events. We have begun to determine the relationships that exist between quantifiable ash characteristics and volcanic electrification, especially the occurrence of CRF. We have found that CRF occurred during events where ash samples were composed of greater than 60% glass with less than 10% lithics. CRF was also present during eruptions whose samples have have high mean roundness but maintain a distribution tail of acicular grains. Finally, CRF occurred in more explosive events as defined by higher seismic amplitudes (\u3e7um). We infer from these relationships that CRF is generated in highly explosive events by a combination of initial and secondary fragmentation of the ash as it is generated and travels up the conduit

Monitoring the Development of Volcanic Eruptions through Volcanic Lightning: A Statistical Investigation into Volcanic Electrification and Seismic/Infrasound Signals

A goal for the adoption of volcanic lightning to volcanic monitoring systems is to understand what the presence of volcanic lightning/electrification can tell us about the ongoing eruption dynamics at the volcano. We used a lightning mapping array (LMA) with a two-array network of (2) seismic and (6) infrasound sensors deployed at Sakurajima Volcano, Japan from 29 May - 07 June 2015 to examine this relationship. Through multi-variable statistical analysis, using logistic and linear models, we have determined the relationships between commonly recorded seismic and infrasound measurements and quantified metrics of volcanic electrification. Advancements in this work over the past year have expanded our understanding of these complex relationships. By examining over 1500 total events, of which ~600 had measured electrical activity, we are able to show how increases in the explosive nature of the eruption effect the resulting electrification of the volcanic plume. Results show specifically that the amount of energy partitioned into the air as infrasound has a significant relationship with the presence of continual radio frequency signals and the presence of lightning flashes. Additionally, the interaction between seismic and infrasound signals is statistically significant for the overall duration of electrical activity and the total number of electrical sources detected by the LMA. These statistical models will help create a base for understanding how recorded volcanic lightning may be used to monitor volcanic eruptions by helping estimate eruption parameters