Geologic mapping at the base of Volcán Barú, Panama, characterizes two large andesitic volcanic debris avalanche deposits attributed to sector collapse at Volcán Barú. The older Caisán debris avalanche deposit is at or beyond the radiocarbon dating range, >43,500 yr B.P., whereas the younger Barriles debris avalanche deposit is constrained by two radiocarbon ages that are ca. 9000 yr B.P. The total runout length of the Caisán deposit was ~50 km, covering nearly 1200 km2. The Barriles deposit extended to ~45 km and covered >990 km2, overlapping most of the Caisán. Over 4000 hummocks from these deposits were digitized, and statistical analysis of hummock location and geometry depicts flow patterns of highly fragmented material affected by underlying topography and also helps to define the shorter runout limit of the Barriles deposit. The Barriles and Caisán deposits are primarily unconfined deposits that are among the world's most voluminous subaerial debris avalanche deposits.
Two different geospatial procedures, utilizing deposit thicknesses and edifice reconstruction, yield calculated volumes ~30 km3 and larger for both deposits. Subaerial deposits of comparable scale include those from Mount Shasta, Socompa, and Shiveluch. Currently, the modern edifice is 200–400 m lower than the estimated precollapse Barriles and Caisán summits, and only 16%–25% of the former edifice has been replaced since the last failure. The ~10 km3 postcollapse lava-dome complex, however, implies a Holocene magma production rate of 1.1 km3/k.y., comparable to elevated eruptive pulses documented at other stratovolcanoes, underscoring the importance of hazards assessment and monitoring of this active volcano.
Available at: http://works.bepress.com/william-rose/10/