Abstract
Accurate volcanic eruption forecasting is especially challenging at open vent volcanoes with persistent low levels of activity and relatively sparse permanent monitoring networks. We present a description of seismicity observed at Fuego volcano in Guatemala during January of 2012, a period representative of low-level, open-vent dynamics typical of the current eruptive period. We use this time to establish a baseline of activity from which to build more accurate forecasts. Seismicity consists of both harmonic and non-harmonic tremor, rockfalls, and a variety of signals associated with frequent small eruptions. In addition, there are many small discrete events not necessarily linked to eruptions that we examine in detail here. Using arrival times recorded on a temporary, nine-station network on the edifice of Fuego, we compute a 1-D velocity model and use it to locate earthquakes. The discrete events include 5 families of repeating events. This type of description can act as a template for establishing monitoring efforts at under-studied volcanoes around the world.
Highlights
Increased seismic activity is often the most discernable indicator of volcanic unrest (Tilling, 2008), and seismic monitoring of volcanic environments is an essential component of any volcano observation endeavor
Our proposed template for a temporary monitoring network starts with selecting sites to ensure adequate radial coverage around a volcano
Visual observations recorded by time lapse cameras help aid later interpretation
Summary
Increased seismic activity is often the most discernable indicator of volcanic unrest (Tilling, 2008), and seismic monitoring of volcanic environments is an essential component of any volcano observation endeavor. Eruptive episodes can persist over time scales from days to years, and in rare cases decades (Siebert et al, 2011) These “open-vent” volcanoes (Rose et al, 2013)— where connections between a magma body and the atmosphere are already established, or “quiescently active” (Stix, 2007) or “persistently restless” (Rodgers et al, 2013) volcanoes—where those connections open and close due to seemingly small changes within a system, provide opportunities for understanding volcanism as a phenomenon, and present unique challenges for hazard mitigation (see Rose et al, 2013 for a review). When a volcano already exhibits frequent explosive eruptions, nearly continuous gas emission, and abundant volcanic seismicity, indicators that precede a shift to more dangerous levels of activity may be subtle (Roman et al, 2016) In these open systems, it is important to understand more detail about the seismicity to recognize changes in complex, low-level signals. Establishing a long, detailed, and well understood baseline of eruptive activity levels is one way to facilitate more accurate medium term forecasts (Tilling, 2008), and can be especially valuable in open vent situations (National Academies of Sciences, Engineering, and Medicine, 2017)
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