Academic Journal
A Combined Field and Numerical Approach to Understanding Dilute Pyroclastic Density Current Dynamics and Hazard Potential: Auckland Volcanic Field, New Zealand
| العنوان: | A Combined Field and Numerical Approach to Understanding Dilute Pyroclastic Density Current Dynamics and Hazard Potential: Auckland Volcanic Field, New Zealand |
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| المؤلفون: | Brand, Brittany D., Gravley, Darren, Clarke, Amanda, Lindsay, Jan, Boomberg, Simon H., Agustin-Flores, Javier, Németh, Károly |
| المصدر: | Geosciences Faculty Publications and Presentations |
| بيانات النشر: | ScholarWorks |
| سنة النشر: | 2014 |
| المجموعة: | Boise State University: Scholar Works |
| مصطلحات موضوعية: | Auckland Volcanic Field, phreatomagmatic, Maar, base surge, volcanic hazard assessment, CGISS, Earth Sciences, Geophysics and Seismology |
| الوصف: | The most dangerous and deadly hazards associated with phreatomagmatic eruption in the Auckland Volcanic Field (AVF; Auckland, New Zealand) are those related to volcanic base surges - dilute, ground-hugging, particle laden currents with dynamic pressures capable of severe to complete structural damage. We use the well-exposed base surge deposits of the Maungataketake tuff ring, (Manukau coast, Auckland) to reconstruct flow dynamics and destructive potential of base surges produced during the eruption. The initial base surge(s) snapped trees up to 0.5 m in diameter near their base as far as 0.7-0.9 km from the vent. Beyond this distance the trees were encapsulated and buried by the surge in growth position. Using the tree diameter and yield strength of the wood we calculate that dynamic pressures (Pdyn) in excess of 12–35 kPa are necessary to cause the observed damage. Next we develop a quantitative model for flow of and sedimentation from a radiallyspreading, dilute pyroclastic density currents (PDCs) to determine the damage potential of the base surges produced during the early phases of the eruption and explore the implications of this potential on future eruptions in the region. We find that initial conditions with velocities on the order of 65 m s- 1, bulk density of 38 kg m-3 and initial, near-vent current thicknesses of 60 m reproduce the fieldbased Pdyn estimates and runout distances. A sensitivity analysis revealed that lower initial bulk densities result in shorter run-out distances, more rapid deceleration of the current and lower dynamic pressures. Initial velocity does not have a strong influence on run-out distance, although higher initial velocity and slope slightly decrease runout distance due to higher rates of atmospheric entrainment. Using this model we determine that for base surges with runout distances of up to 4 km, complete destruction can be expected within 0.5 km from the vent, moderate destruction can be expected up to 2 km, but much less damage is expected up to the final runout ... |
| نوع الوثيقة: | text |
| وصف الملف: | application/pdf |
| اللغة: | unknown |
| Relation: | https://scholarworks.boisestate.edu/geo_facpubs/186; https://scholarworks.boisestate.edu/context/geo_facpubs/article/1186/viewcontent/Brand___A_combined_field_and_numerical_approach___typeset.pdf |
| الاتاحة: | https://scholarworks.boisestate.edu/geo_facpubs/186 https://scholarworks.boisestate.edu/context/geo_facpubs/article/1186/viewcontent/Brand___A_combined_field_and_numerical_approach___typeset.pdf |
| Rights: | NOTICE: this is the author’s version of a work that was accepted for publication in Journal of Volcanology and Geothermal Research . Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Volcanology and Geothermal Research , (2014). DOI: 10.1016/j.jvolgeores.2014.01.008 |
| رقم الانضمام: | edsbas.27F638D1 |
| قاعدة البيانات: | BASE |
| الوصف غير متاح. |