NSFGEO-NERC: Physical and Chemical Constraints on Large-volume Pyroclastic Blasts: The Campanian Ignimbrite Eruption, Italy

GSTDTAP

项目编号	1761713
	NSFGEO-NERC: Physical and Chemical Constraints on Large-volume Pyroclastic Blasts: The Campanian Ignimbrite Eruption, Italy
	Michael Ort
主持机构	Northern Arizona University
项目开始年	2018
	2018-04-01
项目结束日期	2021-03-31
资助机构	US-NSF
项目类别	Standard Grant
项目经费	290655(USD)
国家	美国
语种	英语
英文摘要	Pyroclastic density currents, mixtures of volcanic ash and pumice (also known as pyroclasts) and gas that move at high rates of speed, are some of the most destructive forces in nature. The Campanian Ignimbrite, which erupted from the Campi Flegrei near Naples, Italy, 40,000 years ago, is the deposit from one of the youngest truly large pyroclastic density currents on Earth. The currents reached over 80 km from the vent and devastated an area currently occupied by more than 4 million people. Traditional models for these currents assume they are tens to perhaps 100 meters thick, but our past work shows the Campanian current moved as a kilometer-thick flow across the landscape, overtopping ridges 1.5 times that height. This great mobility makes this sort of "expanded" pyroclastic density current much more hazardous and the damage less predictable. This dilute current required an enormous amount of gas, more than can be explained by the amount dissolved in the magma prior to eruption. Two other possible sources are the entrainment of air and the involvement of water from a hot hydrothermal system within the volcano. This project will determine the amounts of gas from the magma, air, and hydrothermal system involved in the current. This information will be used to make better predictions of which volcanoes might produce highly mobile currents and design hazards maps that take this mobility into account. Two undergraduate students, two graduate students, a post-doctoral researcher, and a professor will work on this project at Northern Arizona University and a graduate student and a professor will work at Oxford University. Three Italian researchers will also collaborate in this project. The results may be used for hazards assessments and response plans, including for the US Naval Support Activity in Naples. A recent thermal magnetization study of the Campanian Ignimbrite (CI) found the temperature of emplacement was above 580 oC even at 80 km from the vent. This limits how much air could have been incorporated, but, to calculate precise quantities, a better knowledge of the magmatic temperature and whether other sources of gas, such as magmatic gas and hydrothermal fluids, were significant, is needed. This project will include 1) field investigations to better characterize the CI stratigraphy and link distal and proximal deposits and define the relative timing of volcanic events; 2) complete volatile analysis (H2O, CO2, S, F and Cl) of melt inclusions and apatite microphenocrysts via Fourier Transform Infrared (FTIR) spectroscopy, ion probe, and electron microprobe. Back-calculating volatile concentrations during open-system degassing is a new technique that should reveal much about the Campanian Ignimbrite magma history; and 3) a study of the glass transition temperature at varying strain rates and residual water contents to better define the emplacement temperature. Current models and interpretations of datasets may need to be modified to include the potential role of hydrothermal fluids in "supercharging" an eruption, as hydrothermal water does not appear in many petrologic measurements of gases. A model for explosive eruptions that includes the potential contribution of erupted hydrothermal systems will help define volcanic hazards more accurately and may elucidate a possible cause for paroxysmal pyroclastic density current-producing eruptions. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/72459
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Michael Ort.NSFGEO-NERC: Physical and Chemical Constraints on Large-volume Pyroclastic Blasts: The Campanian Ignimbrite Eruption, Italy.2018.