Volcanic eruptions pose a significant and sometimes unpredictable hazard, especially at systems that display little to no precursory signals. For example, the 2008 eruption of Okmok volcano in Alaska notably lacked observable short‐term precursors despite years of low‐level unrest. This unpredictability highlights that direct monitoring alone is not always enough to reliably forecast eruptions. In this study, we use the Ensemble Kalman Filter (EnKF) to produce a successful hindcast of the Okmok magma system in the lead up to its 2008 eruption. By assimilating geodetic observations of ground deformation, finite element models track the evolving stress state of the magma system and evaluate its stability using mechanical failure criteria. The hindcast successfully indicates an increased eruption likelihood due to tensile failure weeks in advance of the 2008 eruption. The effectiveness of this hindcast illustrates that EnKF‐based forecasting methods may provide critical information on eruption probability in systems lacking obvious precursors.
- NSF-PAR ID:
- 10272179
- Date Published:
- Journal Name:
- IEEE IGARSS
- Page Range / eLocation ID:
- 3618 to 3621
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Extensive vertical deformation (>4.5 m) observed at Sierra Negra volcano Galápagos, Ecuador, between 1992 and the 2005 eruption led scientists to hypothesize that repeated faulting events relieved magma chamber overpressure and prevented eruption. To better understand the catalyst of the 2005 eruption, thermomechanical models are used to track the stress state and stability of the magma storage system during the 1992–2005 inflation events. Numerical experiments indicate that the host rock surrounding the Sierra Negra reservoir remained in compression with minimal changes in overpressure (~10 MPa) leading up to the 2005 eruption. The lack of tensile failure and minimal overpressure accumulation likely inhibited dike initiation and accommodated the significant inflation without the need for pressure relief through shallow trapdoor faulting events. The models indicate that static stress transfer due to the Mw5.4 earthquake 3 hr prior to the eruption most likely triggered tensile failure and catalyzed the 2005 eruption.
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Significance Statement Water crises are occurring with increasing severity and frequency around the globe. The ability to accurately forecast wet season rainfall would be invaluable to water managers and other decision-makers. Here, we explore the reasons behind the failure of a suite of operational seasonal forecast models to accurately predict rainfall in the Cape Town region of South Africa.
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/IGARSS39084.2020.9323109
