RAPID: Documenting the development of a lava delta at the 2018 Lower East Rift Zone eruption of Kilauea Volcano

2018年4月，正在喷发的基拉韦厄火山发生了戏剧性的变化。山顶的熔岩湖和活跃了35年的普乌火山口都灾难性地干涸了，岩浆被送到了下东部裂谷区，在那里开始喷发。在那之后的大部分时间里，从裂谷带裂缝中喷出的熔岩穿过沿海平原，到达海洋，在那里它分裂并沉积在沿海水域。本研究的目的是在正在进入海洋的地点进行多波束测深测量，以绘制熔岩沉积的范围和体积，并描述形成海底熔岩三角洲和影响新形成海岸线稳定性的沉积和崩塌机制。基拉韦厄火山的入海口是夏威夷火山最危险的地区之一，因为熔岩三角洲的反复崩塌可能导致严重的爆炸和当地的海啸。这些崩溃在很大程度上是没有预警的。该项目将收集必要的数据，以评估缓解这种危险所需的熔岩三角洲崩塌机制。美国地质调查局的夏威夷火山观测站是这个项目的合作伙伴。虽然熔岩可以完整地穿过陆-海界面，形成浅层海底熔岩流，但更常见的是熔岩在进入海洋时由于熔岩-海水相互作用而破碎。因此，熔岩三角洲主要是由火山碎屑物质以及三角洲向陆部分崩塌时产生的熔岩块构成的。一些研究已经从陆上观测考察了熔岩三角洲的形成，但很少有研究能够直接观察三角洲形成过程中的海底部分。因此，正在进行的基拉韦厄火山喷发提供了一个极好的机会来描述熔岩三角洲是如何形成的，崩塌的规模和机制，以及这些过程与熔岩通量（例如，穿过陆地-海洋界面）和其他环境参数（例如，地震活动性，波浪气候）的关系。绘制海底环境中熔岩沉积的早期阶段的地图将作为重复测深调查的基线，可以将岩浆系统的地球物理和地球化学监测（例如地震活动、变形、气体地球化学）与熔岩喷发的体积和速率之间的关系联系起来。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

In April 2018, a dramatic shift took place in the ongoing eruption of Kilauea volcano. Both the summit lava lake and the vent at Puu Oo, active for 35 years, catastrophically drained, sending magma to the Lower East Rift Zone where it began to erupt. During much of the time since then, lava erupting from rift zone fissures has traversed the coastal plains and reached the ocean, where it breaks apart and is deposited in coastal waters. The objective of this study is to conduct a multibeam bathymetric survey at the sites of the ongoing ocean entry to map the extent and volume of lava deposition and characterize the mechanisms of deposition and collapse that shape the submarine lava delta and influence the stability of the newly formed coastline. Ocean entry sites on Kilauea Volcano are among the most volcanically hazardous areas in Hawaii, as recurring collapses of lava deltas can cause significant explosions and local tsunamis. These collapses occur largely without warning. This project will collect the data necessary to evaluate the mechanisms of lava delta collapse that are required to mitigate this hazard. The United States Geological Survey's Hawaii Volcanoes Observatory is a partner on this project.Although lava can cross the land-ocean interface intact and build shallow submarine lava flows, more commonly lava is fragmented due to lava-seawater interaction as it enters the ocean. As a result, lava deltas are largely constructed with volcaniclastic material along with lava blocks generated during the collapse of the landward portion of the deltas. Several studies have examined the formation of lava deltas from subaerial observations, but few studies have been able to directly observe the submarine portions of deltas during formation. As such, the ongoing eruption of Kilauea offers an excellent opportunity to characterize how lava deltas are formed, the magnitude and mechanisms of collapse, and the relationship of these processes to lava flux (e.g., across the land-ocean interface) and other environmental parameters (e.g., seismicity, wave climate). Mapping the early stages of lava deposition in the submarine environment will serve as a baseline for repeat bathymetric surveys that could close the loop on the relationship between geophysical and geochemical monitoring of the magmatic system (e.g., seismicity, deformation, gas geochemistry) and the volumes and rates of lava erupted.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.