An eruption occurred in November 1987 but was not observed by geologists. Residents of the area near the E side of the crater reported an incandescent column and loud bangs but said that the eruption was less intense than others in recent years. Newspapers printed photographs of a small eruption column.

Geologists found small fresh basaltic bombs 50 m from the E rim of the crater that may have been from the eruption. A vent 30-50 m wide had opened in the NE corner of the crater. The maximum temperature on a rock surface in the new vent was 246°C. Fumarolic activity was markedly stronger than in 1985-86, when only one large fumarole had been present, on the N side of the crater. In January 1988, there were fumaroles on all sides of the crater and on its floor (figure 1). At least one was emitting gas with a loud roar, and the plume was visible from 5 km away.

Figure 1. Sketch map of Telica on 17 January 1988. Temperatures were taken with an infrared radiometer measuring surface brightness temperature in the 8-14 µm range with emissivity set at 1. Temperature measurements of the numbered points were taken from about 500 m away, with a 60-80 m resolution, unless otherwise noted in parentheses. Crater walls are vertical and fumaroles inaccessible. Fumaroles and hot areas are stippled. Measured temperatures: (1) 131°C (60 m2), 60-80°C (1,000 m2); (2 & 3) 50°C (fissures); (4) 60-70°C (1,000 m2); (5) 96°C (25 m2), 60°C (100 m2), 50°C (1,000 m2); (6) 47°C (fissure 10 m long); (7) 245°C (100 m2, including new crater), 100°+C (250 m2), 60-100°C (1,000 m2 – rock slabs); (8) 50-60°C (fissure 30 m long); (9) 45°C (small fumaroles).

The fumarole field [at San Jacinto Hot Springs] had temperatures no higher than 101°C on 17 January.

Geological Summary. Telica, one of Nicaragua's most active volcanoes, has erupted frequently since the beginning of the Spanish era. This volcano group consists of several interlocking cones and vents with a general NW alignment. Sixteenth-century eruptions were reported at symmetrical Santa Clara volcano at the SW end of the group. However, its eroded and breached crater has been covered by forests throughout historical time, and these eruptions may have originated from Telica, whose upper slopes in contrast are unvegetated. The steep-sided cone of Telica is truncated by a 700-m-wide double crater; the southern crater, the source of recent eruptions, is 120 m deep. El Liston, immediately E, has several nested craters. The fumaroles and boiling mudpots of Hervideros de San Jacinto, SE of Telica, form a prominent geothermal area frequented by tourists, and geothermal exploration has occurred nearby.

Information Contacts: B. van Wyk de Vries, H. Rymer, and G. Brown, Open Univ; P. Hradecky and H. Taleno, INETER.