Characterization of seismicity at Volcán Barú, Panama: May 2013 through April 2014

• Published in: Journal of volcanology and geothermal research Vol. 328; pp. 187 - 197
• Main Authors: Hopp, Chet J., Waite, Gregory P.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.12.2016
• Subjects: Barú; Double-difference relocation; Focal mechanisms; Panama; Seismicity; Template matching; Velest; Double-difference relocation; Panama; Barú; Focal mechanisms; Velest; Template matching; Seismicity
• ISSN: 0377-0273; 1872-6097
• DOI: 10.1016/j.jvolgeores.2016.11.002

Volcán Barú, in the western province of Chiriquí, is Panama's youngest and most active volcano. Although Barú has experienced no historic eruptions, there have been four eruptive episodes in the last 1600 years, the most recent occurring 400–500 years ago (Sherrod et al., 2007). In addition, there have been four reported earthquake swarms in the last 100 years. The most recent swarm occurred in May of 2006, prompting a USGS hazard assessment (Sherrod et al., 2007). In order to characterize local seismicity and provide a reference for future monitoring efforts, we established a seismic network that operated from May 2013 through April 2014. The network consisted of eight temporary, single-component, short-period sensors loaned by OSOP Panama, and three permanent stations distributed over a 35 by 15 km area. During operation of the network, 91 local events were detected and located. These events were used to calculate a new 1-D velocity model for the region surrounding Barú. Of particular interest was a cluster of events located less than 5 km east of Barú at a depth of roughly 5km. We used a template matching detection technique to identify another 47 smaller magnitude events in the area of this cluster. The largest events in the cluster exhibit a broad range of frequencies extending up to 20 Hz and focal mechanisms calculated for eight of the events suggest strike-slip and reverse faulting are the predominant source processes. The directions of maximum compression shown by these focal mechanisms are approximately radial with respect to the volcano, which may reflect the influence of a magmatic source beneath the edifice. •A new, year-long earthquake catalog for Volcán Barú is presented.•91 local events were detected and located.•Template matching was used to detect 47 new events from a cluster of six.•P-axes for local events are rotated ∼90 degrees relative to regional trend.