Volcanic Conduit Processes and Strombolian Eruption Cycles

火山管道过程和斯特龙博利火山喷发周期

• 批准号: 0207734
• 负责人: Andrew J. Harris
• 金额: $ 19.6万
• 依托单位: University of Hawaii
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-08-01 至 2006-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0207734&HistoricalAwards=false
• 关键词: Volcanic; Conduit; Processes; Strombolian; Eruption

Volcanic Conduit Processes and Strombolian Eruption CyclesEAR-0207734PIs: Harris & HoughtonOur aim in this project is to understand the driving forces behind volcanoes that display persistent, strombolian activity. Such activity is characterized by repeated, mildly explosive events. For such repetitive explosive activity to be maintained over hundreds-to-thousands of years, as it has been at Stromboli Volcano (Italy), a volcano must be fed by a stable supply of magma and gas. It has not yet been determined, however, whether this supply occurs by the repeated rise of discrete magma batches or by a continuous stream.Initial measurements by us at Stromboli during May 1999 indicated that the magma supply to the shallow system may indeed be variable over minutes-to-hour long periods (i.e. it may be batch-like). These supply variations may in turn drive observed variations in the style and frequency of explosive activity. This has led us to develop a working hypothesis that fresh, gas-rich magma batches do rise from depth as discrete pulses, causing fluctuating levels of degassing and hence explosive activity upon their arrival. Our current project builds on those initial measurements by adding new geophysical instrumentation together with more detailed examination of volcanic products. In particular, we will use thermal and infrasound measurements, plus studies of the textures of the erupted lava bombs to examine explosive activity at Stromboli and infer variations in magma level within the conduit. Thermal data acquired during the persistent degassing that occurs between strombolian explosions will be used to characterize periods of enhanced gas escape. Finally, we will use vesicle (gas bubble) and crystal size distributions in the bombs to constrain the extent of mixing between newly arrived magma batches and long-resident magma within the shallow system.

火山管道过程和斯特龙博利火山喷发周期-0207734 PI：哈里斯霍顿我们在这个项目中的目的是了解火山背后的驱动力，显示持续的，斯特龙博利火山活动。 这种活动的特点是反复发生的、轻度爆炸性的事件。 这种重复的爆炸活动要维持数百至数千年，就像在斯特龙博利火山（意大利），火山必须有稳定的岩浆和气体供应。 然而，目前还不能确定这种供应是由不连续的岩浆批次的反复上升还是由连续的流产生的。我们在1999年5月在斯特龙博利进行的初步测量表明，对浅层系统的岩浆供应可能确实在数分钟到数小时的长时间内是可变的（即它可能是批次状的）。 这些供应变化可能反过来驱动观察到的爆炸性活动的风格和频率的变化。 这使我们发展出一个工作假设，即新鲜的、富含气体的岩浆批次确实以离散脉冲的形式从深度上升，导致脱气水平的波动，因此在它们到达时发生爆炸活动。 我们目前的项目是在这些初步测量的基础上增加新的地球物理仪器，并对火山产物进行更详细的检查。特别是，我们将使用热和次声测量，再加上对喷发的熔岩炸弹的纹理的研究，以检查斯特龙博利的爆炸活动，并推断管道内岩浆水平的变化。 在斯特龙博利爆炸之间发生的持续脱气过程中获得的热数据将用于表征增强气体逃逸的时期。 最后，我们将使用囊泡（气泡）和晶体大小分布的炸弹，以限制新到达的岩浆批次和长期居住的岩浆在浅系统之间的混合程度。