2-2-2-2-2-2-2-2-2-2-2-2-2 From: Paul Jarvis <p.jarvis@xxxxxxxxxx> Dear colleagues, *Please note that the time of this seminar will be at 15:00 UTC on Tuesday 26th September, instead of the previously advertised time. Apologies for any inconvenience.* We are thrilled to announce a new venture for the IAVCEI Tephra Hazard Modelling Commission: the *Ashvances in Tephra Seminar Series (ATSS). *Do you have a story to tell about tephra hazard? Then we want to hear it. We anticipate that this virtual seminar series will take place every quarter (c.3 months) depending on interest and will last for about an hour. Each quarter, two speakers will be allocated 15-20-minute talks with 5-10 minutes for questions. The last 10 minutes will be kept for general discussions, e.g., how the Tephra Hazard Modelling Commission can serve you better, and socializing/networking. At least one of the talks will be by an early-career researcher, and we will use this seminar series to showcase the work of researchers with backgrounds underrepresented in volcanology. Time zones will be selected based on the location(s) of speakers and we will aim to rotate these as much as possible to reach audience members from across the globe and give everyone an equal and fair chance to participate in the seminars. We aim that by having two talks per seminar, each session will cover multiple topics, including but not limited to numerical modelling, field studies, laboratory experiments and risk communication/management. Please use this form https://urldefense.com/v3/__https://forms.gle/z7LB3TJDWauD3qCs6__;!!IKRxdwAv5BmarQ!aEt5PqnMQj97nLiLihuJpOdCyXUnMkJHFsSFbhjTx80r4L5suCvCjbI6Ifu5PI6nFxxOPJJEaP7Z-Bgn$ <https://urldefense.com/v3/__https://forms.gle/z7LB3TJDWauD3qCs6__;!!IKRxdwAv5BmarQ!ZYbhk9h-Mu55gmuoIMwvyIC8M7kzQzsnRi4gp6yn6R6g390Oz7FTA4cXbI5RMdelaV_WHtdXISDx-y_Zhg$> to register your interest in being a speaker or suggest a student/colleague. We particularly encourage (self-) nomination of diverse and early career scientists. Our first online ATSS seminar will take place on Tuesday 26th September at *15:00 UTC*. You can join via Microsoft Teams using this link <https://urldefense.com/v3/__https://www.google.com/url?q=https:**Ateams.microsoft.com*l*meetup-join*19*253ameeting_YjgyZmYyNTYtNjgzMy00ZWEzLThkY2MtZGFlZjMxNzgyMzZi*2540thread.v2*0*context*3D*257b*2522Tid*2522*253a*2522912a5d77-fb98-4eee-af32-1334d8f04a53*2522*252c*2522Oid*2522*253a*25226545a20b-9dcc-4b20-a342-7f12159dda79*2522*257d&sa=D&source=calendar&usd=2&usg=AOvVaw0rBGy4rJRmX6E9j7gib6wC__;Ly8vLy8lJS8_JSUlJSUlJSUlJSUlJSU!!IKRxdwAv5BmarQ!ZYbhk9h-Mu55gmuoIMwvyIC8M7kzQzsnRi4gp6yn6R6g390Oz7FTA4cXbI5RMdelaV_WHtdXISCH67d3sQ$>. Our first two speakers are (abstract at the end of email): *Costanza Bonadonna, President of IAVCEI and Professor of Volcanology at University of Geneva *- "Tephra sedimentation and grainsize associated with the 2021 Tajogaite eruption of Cumbre Vieja (La Palma, Canary Islands, Spain)" *Liam Kelly, PhD student at Vanderbilt University *- "Airfall volume of the 15 January 2022 eruption of Hunga volcano estimated from ocean color changes" We look forward to seeing many of you on Tuesday 26th September and to welcoming interest from some great speakers for future seminars. Please donâ??t forget that you can sign-up to our commission and mailing list anytime at this link <https://urldefense.com/v3/__https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=IAVCEITHM&A=1__;!!IKRxdwAv5BmarQ!ZYbhk9h-Mu55gmuoIMwvyIC8M7kzQzsnRi4gp6yn6R6g390Oz7FTA4cXbI5RMdelaV_WHtdXISByX8UyVQ$> . All the best, Alastair, Paul and Thomas Co-chairs of IAVCEIâ??s Tephra Hazard Modelling Commission *Costanza's abstract: *The 2021 hybrid Tajogaite eruption of Cumbre Vieja (La Palma) was mainly effusive, with >70 % of volume erupted as lava and simultaneous explosive activity of variable eruptive styles depositing a widespread tephra blanket. Rapid gas segregation and high magma ascent rate modulated the gas flux at the different vents resulting in short-time fluctuations amongst the different eruptive styles and unsteady tephra ground accumulation. Even though the total grainsize distributions of selected layers, units and of the whole tephra blanket are unimodal, various sedimentation processes were observed including particle aggregation and different types of sedimentation features (e.g., lapilli waves, ash fingers). The analysis of the Tajogaite eruption dynamics highlights the challenges of risk and crisis management associated with long-lasting basaltic pulsatory hybrid eruptions. *Liam's abstract: *On 15 January 2022, Hunga volcano erupted, creating an extensive and high-reaching umbrella cloud over the open ocean, hindering traditional isopach mapping and fallout volume estimation. In MODIS satellite imagery, ocean surface water was discolored around Hunga following the eruption, which we attribute to ash fallout from the umbrella cloud. By relating intensity of ocean discoloration to fall deposit thicknesses in the Kingdom of Tonga, we develop a methodology for estimating airfall volume over the open ocean. Ash thickness measurements from 41 locations are used to fit a linear relationship between ash thickness and ocean reflectance. This produces an airfall volume estimate of ~1.7 km3. The whole eruption produced >10 km3 of pyroclastic units on the sea floor. Our fall estimates suggest that these must be dominated by gravity current deposits. This new ocean-discoloration method provides an airfall volume estimate consistent with other independent measures of the plume and is thus effective for rapidly estimating fallout volumes in future eruptions of volcanoes over oceans. 2-2-2-2-2-2-2-2-2-2-2-2-2 ------------------------------
