@article { LI2022117533, title = {Seismic tremor reveals slow fracture propagation prior to the 2018 eruption at Sierra Negra volcano, Galápagos}, address = {}, booktitle = {}, chapter = {}, edition = {}, editor = {}, eprint = {}, howpublished = {}, institution = {}, journal = {Earth and Planetary Science Letters}, key = {}, location = {}, month = {}, note = {}, number = {}, organization = {}, pages = {117533}, publisher = {}, series = {}, school = {}, url = {https://www.sciencedirect.com/science/article/pii/S0012821X22001698}, volume = {586}, year = {2022}, issn = {}, doi = {https://doi.org/10.1016/j.epsl.2022.117533}, language = {}, accession_number = {}, short_title = {}, author_address = {}, keywords = {SPECFEM3D, volcanic tremor, spectral analysis, tremor location, tremor source process, dike propagation, Sierra Negra}, abstract = {Seismic tremor observed near active volcanoes is an important tool for volcano monitoring as it often appears shortly before eruptions. Although tremor can be generated by a variety of physical processes it is usually interpreted as direct evidence for flowing magma in the sub-surface. These interpretations typically feed into risk assessments for potential eruptions. Using the temporal evolution of tremor amplitude and spectral data from a distributed seismic network that captured the 2018 eruption at Sierra Negra in Galápagos, we determine that tremor is not directly related to sub-surface fluid movement. Instead at Sierra Negra tremor likely indicates a slowly propagating fracture, which is later exploited as a pathway for silent magma flow. Distinct differences in the source migration and the spectral character of pre-eruptive and co-eruptive tremor allow both a location estimate of the future eruption site and a precise timing of the eruption onset.}, call_number = {}, label = {}, research_notes = {}, author = {Li , Ka Lok and Bean , Christopher J. and Bell , Andrew F. and Ruiz , Mario and Hernandez , Stephen and Grannell , James} }