부산대학교 도서관

[Volcanic eruptions generate continuous or episodic tremor, which can provide unrivaled information about activity changes during eruption. However, the wealth of information in episodic tremor patterns is often not harvested and transitions between patterns remain obscure. The 2021 Geldingadalir eruption, Iceland, is an exceptional case, where the lava effusion caused continuous tremor, and 8698 tremor episodes spanning two orders of magnitude in duration and repose. Based on seismometer and video camera data, we associate several‐minute‐long, symmetrical episodes with an open vent system, where lava remains in the crater bowl during repose, connected to a shallow magma compartment. Ramp‐shaped episodes, lasting several hours, are associated with a temporary closure of the vent system, where no lava remains in the crater bowl during repose and more time is required to resume effusion. The transition from continuous to episodic effusion is related to the cumulative time spent in effusion and repose, and to external factors like crater wall collapses. The range of observed eruption styles and shifts between them, took place at unchanged magma supply rate. This underpins the importance of processes, geometry and evolution of the shallow conduit with time.] Plain Language Summary: Volcanic eruptions can provide unrivaled information about the subsurface structure and processes driving it. Often effusion happens continuous over a time span. However, sometimes the effusion starts and stops and is hence episodic. During the 2021 Geldingadalir eruption, Iceland the lava flowed continuously from the vent but later stopped 8698 times. Some of these episodes where a few minutes long, while others lasted several hours. We interpret several‐minute‐long episodes as an open system, where lava remains in the crater during repose. This system can restart fast and easy. During several hour‐long episodes, no lava remains in the crater during repose. The system needs more time to reopen the vent. The system also reacts depending on the time it is in repose or effusion. And finally, external factors like crater wall collapses modify the episodic pattern. The most interesting feature is the range of eruption styles and transitions between them, that occurred at constant magma inflow rate and are hence caused by the shallow conduit. Key Points: The 2021 Geldingadalir eruption, Iceland, featured 8698 tremor episodes of minute to week durationAn open vent system with lava residing in the crater during repose featured minute‐long lava effusion with bell‐ or rectangle‐shaped tremorA semi‐closed vent system with no lava residing in the crater featured hour‐long lava effusion with ramp‐shaped tremor [ABSTRACT FROM AUTHOR]