Interactions between lava flows and surface water are not always considered in hazard assessments, despite abundant historical and geological evidence that they can create significant secondary hazards (e.g., floods and steam explosions). We combine contemporary accounts of the 1783–1784 Laki fissure eruption in southern Iceland with morphological analysis of the geological deposits to reconstruct the lava–water interactions and assess their impact on residents. We find that lava disrupted the local river systems, impounded water that flooded farms and impeded travel, and drove steam explosions that created at least 2979 rootless cones on the lava flow.Using aerial photographs and satellite-derived digital terrain models, we mapped and measured 12 of the 15 rootless cone groups on the Laki lava field. We have identified one new rootless cone group and provide data that suggest another cone group previously attributed to the 939–940 CE Eldgjá eruption was created by the Laki eruption. We then use contemporary accounts to estimate formation dates and environments for each cone group, which formed in wetland/lake areas, on riverbeds, and near areas of impounded water. Furthermore, comparison with previous field studies shows that assessments using remote sensing can be used to identify and map meter-scale and larger features on a lava flow, although remote mapping lacks the detail of field observations.Our findings highlight the different ways in which lava can interact with surface water, threatening people, property, water supplies, and infrastructure. For these reasons, anticipation of such interactions is important in lava flow hazard assessment in regions with abundant surface water; we further demonstrate that remote sensing can be an effective tool for identifying lava–water interactions in past lava flows.

中文翻译：

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1783-1784年Laki裂隙喷发期间熔岩与河流相互作用的危害

尽管有大量的历史和地质证据表明，熔岩流与地表水之间的相互作用会造成重大的次生危害（例如洪水和蒸汽爆炸），但并非总是在危害评估中考虑它们的相互作用。我们将冰岛南部1783-1784年Laki裂隙喷发的当代描述与地质沉积物的形态学分析相结合，以重建熔岩与水的相互作用，并评估其对居民的影响。我们发现熔岩破坏了当地的河流系统，积蓄了水，淹没了农场并阻碍了旅行，并推动了蒸汽爆炸，在熔岩流上至少形成了2979个无根圆锥体。我们使用航空照片和卫星衍生的数字地形模型对地图进行了测量和测量Laki熔岩田的15个无根圆锥群中的12个。我们已经确定了一个新的无根圆锥群，并提供了数据，表明由Laki爆发创建了另一个先前归因于939-940 CEEldgjá爆发的圆锥群。然后，我们使用当代帐户来估计每个圆锥体的形成日期和环境，这些圆锥体是在湿地/湖区，河床和积水附近地区形成的。此外，与以前的实地研究比较表明，尽管远程制图缺乏实地观测的细节，但使用遥感技术进行的评估可用于识别和绘制熔岩流上的水表尺度和较大特征。我们的发现突出了熔岩的不同方式会与地表水相互作用，威胁人员，财产，水供应和基础设施。由于这些原因，在地表水丰富的地区，熔岩流危害评估中，对此类相互作用的预测至关重要。我们进一步证明，遥感可以是识别过去熔岩流中熔岩与水相互作用的有效工具。