Abstract Azerbaijan hosts the highest density of subaerial mud volcanoes on Earth. The morphologies characterizing these structures vary depending on their geological setting, frequency of eruption, and transport processes during the eruptions. Lokbatan is possibly the most active mud volcano on Earth exhibiting impressive bursting events every ∼5 years. These manifest with impressive gas flares that may reach more than 100 meters in height and the bursting of thousands of m3 of mud breccia resulting in spectacular mud flows that extend for more than 1.5 kilometres. Unlike other active mud volcanoes, to our knowledge Lokbatan never featured any visual evidence of enduring diffuse degassing (e.g., active pools and gryphons) at and near the central crater. Only a very small new-born gryphon was intermittently active in 2019 (with negligible flow). Gas flux measurements completed with a closed-chamber technique reveal extremely low values throughout the structure with average CH 4 = 1.36 tonnes yr−1 and CO 2 = 11.85 tonnes yr−1. We suggest that after eruptive events, the mud breccia is able to seal the structure preventing gas release and thereby promoting overpressure build-up in the subsurface. This self-sealing mechanism allows a fast recharge of Lokbatan resulting in more frequent and powerful explosive episodes. Our field observations reveal the presence of large (up to ∼50,000 m3) stratified blocks that were originally part of a large crater cone. These blocks were rafted >1 km from the vent on top of mud breccia flows. We use a model based on lubrication theory to show that it is reasonable to transport blocks this large and this far provided the underlying mud flow was thick enough and the blocks are large enough. The presence of large rafted blocks is not a unique phenomenon observed at Lokbatan mud volcano and is documented at other large-scale structures both onshore and offshore.

中文翻译：

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爆炸性泥火山喷发和泥角砾岩块漂流

摘要 阿塞拜疆拥有地球上密度最高的地下泥火山。表征这些结构的形态因它们的地质环境、喷发频率和喷发期间的运输过程而异。Lokbatan 可能是地球上最活跃的泥火山，每 5 年就会发生一次令人印象深刻的爆发事件。这些表现为令人印象深刻的气体火炬，高度可达 100 多米，数千立方米的泥角砾岩破裂，导致壮观的泥​​流延伸超过 1.5 公里。与其他活泥火山不同，据我们所知，Lokbatan 从未在中央火山口处和附近提供任何持久扩散脱气的视觉证据（例如，活跃的水池和狮鹫）。2019 年只有一只非常小的新生狮鹫间歇性活动（流量可以忽略不计）。使用密闭室技术完成的气体通量测量显示整个结构的数值极低，平均 CH 4 = 1.36 吨 yr-1 和 CO 2 = 11.85 吨 yr-1。我们认为，在喷发事件后，泥角砾岩能够密封结构，防止气体释放，从而促进地下超压积聚。这种自密封机制允许对 Lokbatan 进行快速充电，从而导致更频繁和更强大的爆炸事件。我们的实地观察揭示了大型（高达 50,000 立方米）分层块体的存在，这些块体最初是大型火山口锥的一部分。这些区块被漂流到距泥角砾岩流顶部的通风口 > 1 公里处。我们使用基于润滑理论的模型来表明，如果底层泥浆流足够厚且块体足够大，那么运输这么大和这么远的块体是合理的。大型漂流块的存在并不是在 Lokbatan 泥火山观察到的独特现象，并且在陆上和海上的其他大型结构中都有记录。