Characterization of very-long-period seismicity accompanying summit activity at Kīlauea Volcano, Hawai'i: 2007–2013
Journal of Volcanology and Geothermal Research
Eruptive activity returned to the summit region of Kīlauea Volcano, Hawai'i with the formation of the "Overlook crater" within the Halema'uma'u Crater in March 2008. The new crater continued to grow through episodic collapse of the crater walls and as of late 2013 had grown into an approximately elliptical opening with dimensions of~160 × 215 m extending to a depth of~200 m. Occasional weak explosive events and a persistent gas plume continued to occur through 2013. Lava was first observed in
... first observed in the new crater in September 2008, and through 2009 the lava level remained deep in the crater and was only occasionally observed. Since early 2010 a lava lake with fluctuating level within the Overlook crater has been nearly continuously present, and has reached to within 22 m of the Overlook crater rim. Volcanic activity at Kīlauea Volcano is episodic at all time scales and the characterization of very-long-period seismicity in the band 2-100 s for the years 2007-2013 illuminates a portion of this broad spectrum of volcanic behavior. Three types of very-long-period events have been observed over this time and each is associated with distinct processes. Type 1 events are associated with vigorous degassing and occurred primarily between 2007 and 2009. Type 2 events are associated with rockfalls onto the lava lake and occurred primarily after early 2010. Both of these event types are induced by pressure and momentum changes at the top of the magma column that are transmitted downward to a source centroid~1 km below the northeast corner of the Halema'uma'u Crater where the energy couples to the solid Earth at a geometrical discontinuity in the underlying dike system. Type 3 events are not related to surficial phenomena but are associated with transients in mass transfer that occur within the dike system. Very-long-period tremor has also accompanied the return of eruptive activity, with increasing amplitude associated with hours-to months-long changes in gas emission rates and summit deformation. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).