Numerical simulation of basaltic lava flows in the Auckland Volcanic Field, New Zealand—implication for volcanic hazard assessment
Numerical simulation of basaltic lava flows in the Auckland Volcanic Field, New Zealand—implication for volcanic hazard assessment
复制标题
新西兰奥克兰火山场玄武质熔岩流数值模拟——对火山灾害评估的启示
作者：
G. Kereszturi;A. Cappello;G. Ganci;J. Procter;K. Németh;C. Negro;S. Cronin
单成因火山场，如新西兰的奥克兰火山场（AVF），在地球表面很常见，通常由长达10公里的玄武岩熔岩流主导。在靠近人口和基础设施的单成因火山区，熔岩流是一个重大威胁。本文利用MAGFLOW热流变模型重建了AVF部分玄武岩喷发的熔岩流侵位条件。利用MAGFLOW模拟了AVF中8个现有的熔岩流，并通过光探测和测距（LiDAR）衍生的数字地形模型（dtm）测量了喷发体积。将模拟结果与实际熔岩流的尺寸相匹配，可以深入了解它们的就位机制和条件，如渗出率和可能的喷发持续时间。通过观察不同环境下的就位情况，计算出所研究的AVF喷发的岩浆上升速率可能在0.1米/秒左右。在AVF中，过去熔岩流的典型估计持续时间从最小2天的小体积流，如小Rangitoto (0.0015 km3)，到83天的大体积流，如三王（0.078 km3）。三个最佳拟合模拟被用来为AVF建立未来火山危险地图的喷发情景。还提供了喷发持续时间的推断，这将有助于为这一人口稠密的火山地区制定切合实际的应急管理计划和恢复情景。
Monogenetic volcanic fields, such as the Auckland Volcanic Field (AVF), New Zealand, are common on the Earth’s surface and are typically dominated by basaltic lava flows up to 10 s of km long. In monogenetic volcanic fields located in close proximity to human population and infrastructure, lava flows are a significant threat. In this study, lava flow emplacement conditions for some basaltic eruptions of the AVF were reconstructed using the thermo-rheological MAGFLOW model. Eight existing lava flows in the AVF were simulated using MAGFLOW and eruptive volumes measured from Light Detection and Ranging (LiDAR)-derived digital terrain models (DTMs). Fitting the simulations to the dimensions of actual lava flows provides insight into their emplacement mechanisms and conditions, such as effusion rate, and probable eruption durations. By looking at emplacement in different settings, the likely magma ascent rate for studied AVF eruptions is calculated to have been on the order of 0.1 m/s. In the AVF, the typical estimated duration of past lava flows was from a minimum of 2 days for small-volume flows, such as Little Rangitoto (0.0015 km3), up to 83 days for large volume flows, such as Three Kings (0.078 km3). The three best-fitting simulations were used to establish eruption scenarios for future volcanic hazard mapping for the AVF. Inferences of eruption duration that will be useful for developing realistic emergency management plans and recovery scenarios for this densely populated volcanic field are also provided.