More than ten years of Lusi: A review of facts, coincidences, and past and future studies

The Lusi mud eruption in East Java, Indonesia, has continued unabated for more than ten years with no end in sight. This review summarizes what has been learned about this intriguing system, from its inception to the current (2017) well-established metastable geysering system that continuously erupts mud breccia, gas, steam, and water. We discuss the initiation of Lusi, highlighting discrepancies and evidence through the published data, to build a comprehensive database that emphasizes how the results converge towards a natural scenario of this system. We argue that attempts to understand, constrain, or predict the behaviour of this system that rely on a drilling trigger can not explain subsequent observations. On the other hand, we show that a well-constrained conceptual model recognizing Lusi as a volcanically-linked hydrothermal system, has provided important insights for the documented observations over the last eleven years. The response of Lusi to the Yogykarta earthquake falls directly within the range of earthquake triggering phenomena (globally) of similar hydrothermal/geothermal systems, suggesting a natural trigger as the more likely culprit for the Lusi phenomenon. We also offer some future directions of additional scrutiny for understanding this newborn, tectonic scale, volcanic-hydrothermal complex