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转变。山顶的熔岩湖和Puu Oo的火山口都活跃了35年，灾难性地排干了岩浆，将岩浆送到了下东裂谷带，在那里开始喷发。 在此后的大部分时间里，从裂谷带裂缝喷发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沃茨。这项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，并说明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塌陷机制。基拉韦厄火山的入海点是夏威夷火山最危险的地区之一，因为熔岩三角洲的反复坍塌可能导致重大爆炸和局部海啸。这些崩溃在很大程度上是在没有警告的情况下发生的。该项目将收集必要的数据，以评估减轻这一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该项目的合作伙伴。虽然熔岩可以完整地穿过陆地-海洋界面并形成浅的海底熔岩流，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，熔岩三角洲大部分是由火山碎屑物质沿着着三角洲向陆地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中研究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流量的关系（例如，跨越陆地-海洋界面）和其它环境参数（例如，地震活动、波浪气候）。绘制海底环境中熔岩沉积早期阶段的地图将作为重复测深调查的基线，这可以闭合岩浆系统的地球物理和地球化学监测之间关系的回路（例如，该奖项反映了NSF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.