Report on Rincon de la Vieja (Costa Rica) — January 1994
Bulletin of the Global Volcanism Network, vol. 19, no. 1 (January 1994)
Managing Editor: Richard Wunderman.
Rincon de la Vieja (Costa Rica) New seismic data, but still relatively quiet
Please cite this report as:
Global Volcanism Program, 1994. Report on Rincon de la Vieja (Costa Rica). In: Wunderman, R (ed.), Bulletin of the Global Volcanism Network, 19:1. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199401-345020.
Rincon de la Vieja
10.83°N, 85.324°W; summit elev. 1916 m
All times are local (unless otherwise noted)
During 1993 Rincón de la Vieja continued fumarolic venting in Rincón crater. Gas columns rose to 500 m high and contained sufficient gas concentrations to irritate the eyes and sting the skin of observers on the crater margin. The crater lake was clear gray in color, with clouds of suspended sulfur and several areas of discontinuous bubbling. It had a temperature of 35°C.
When seismically active, as in January and September 1993 (figure 8), both high- and low-frequency signals were common. A swarm of 25 high-frequency events took place on 26-29 January. On 26 March, 10 small-amplitude high-frequency events registered, their S - P (S minus P) times were <1.6 seconds. In January 1993 there was a lapse of 16 days in the record, and consequently the number of earthquakes for the month on figure 8 was adjusted [assuming the other recorded days suitably reflect the average seismicity for the whole month]. The January 1994 events were of low-frequency, some with durations over 1 minute. Until July 1993 the volcano deflated radially at a rate of 11 µrad/year; in contrast, the majority of intervals as far back as 1987 showed little or no change. Deflation was unreported in August through January.
|Figure 8. Seismic events at Rincón de la Vieja received at station RIN3, 5 km SW of the active crater, January 1993-January 1994 (October-December 1993 data presumed unrecorded). Courtesy of OVSICORI.|
Geologic Background. Rincón de la Vieja, the largest volcano in NW Costa Rica, is a remote volcanic complex in the Guanacaste Range. The volcano consists of an elongated, arcuate NW-SE-trending ridge that was constructed within the 15-km-wide early Pleistocene Guachipelín caldera, whose rim is exposed on the south side. Sometimes known as the "Colossus of Guanacaste," it has an estimated volume of 130 km3 and contains at least nine major eruptive centers. Activity has migrated to the SE, where the youngest-looking craters are located. The twin cone of 1916-m-high Santa María volcano, the highest peak of the complex, is located at the eastern end of a smaller, 5-km-wide caldera and has a 500-m-wide crater. A plinian eruption producing the 0.25 km3 Río Blanca tephra about 3500 years ago was the last major magmatic eruption. All subsequent eruptions, including numerous historical eruptions possibly dating back to the 16th century, have been from the prominent active crater containing a 500-m-wide acid lake located ENE of Von Seebach crater.
Information Contacts: E. Fernández, J. Barquero, R. Van der Laat, F. de Obaldia, T. Marino, V. Barboza, and R. Sáenz, OVSICORI.