Smithsonian Institution
Global Volcanism Network Bulletin v. 20, no. 5, May 1995

Pacaya (Guatemala)  Eruption on 1 June produces ashfall and lava
      flows

Pacaya
S Guatemala
14.38N, 90.60W; summit elev. 2,552 m
All times are local (= GMT - 6 hours)

Pacaya erupted between 0630 and 0700 on 1 June, sending up a
6-km-high plume. Hot ash burned vegetation and damaged
radio-antenna equipment near the summit. A thin layer of ash
extended a few kilometers from the vent, with ashfall reported 2.5
km N in San Francisco de Sales and 3.5 km W in El Patrocinio
(figure 1). A plume visible at 0715 on GOES-8 satellite images was
moving SE at ~19 km/hr, prompting a NOAA Volcano Hazard Alert at
1000. Analysis based on comparison of wind shear data and observed
translation of the plume suggested that the plume rose to ~9 km
altitude. Eddie Sanchez noted that venting ash destroyed the 1984
spatter cone (Bulletin v. 10, no. 3), called "El Hornito," located
roughly midway between the N caldera rim (Cerro Chino) and the
previously active MacKenney cone (figure 2). In place of El Hornito
was a small crater venting lava, a substantial amount of which
flowed S.

Otoniel Matias reported that on 10 June a small newly constructed
spatter cone had collapsed. A news report described two strong
explosions in the early afternoon and a thick column of smoke.
Matias said that on 14 June more lava erupted, but compared to
earlier phases there was less airborne ash and venting gases, and
the plume reached only 150-200 m above the crater floor. In accord
with this observation, SAB failed to image a plume at 0845 on 14
June; they estimate that a plume must have a height of  >3,000 m
for them to detect it. Matias went on to say that the 14 June
eruption continued vigorously for two hours without pause. Lava
continued to escape as of 16 June, and one or more lava flows had
moved S for a distance of ~600 m.

Pacaya sits 30 km S of the center of Guatemala City (figure 1),
with its population of >1.5 million. An eruption in 1989 produced
a 4.5-km-tall eruption column that enlarged the MacKenney crater.
Lava flows followed in 1990-91. Strong eruptive activity in
June-August 1991 destroyed part of the MacKenney cone and damaged
villages to the W. The volcano's olivine basaltic lavas have often
flowed out of the collapsed SSW sector, traveling away from most of
the nearby inhabited areas. The international airport (La Aurora)
lies ~23 km from the crater and airplanes commonly fly over the
volcano (figure 3).

Information Contacts: Eddie Sanchez and Otoniel Matias, Seccion
Vulcanologia, INSIVUMEH, 7A Avenida 14-57, Zona 13, Guatemala City,
Guatemala; Grace Swanson, Synoptic Analysis Branch - Room 401,
NOAA/NESDIS, 5200 Auth Road, Camp Springs, MD 20746 USA.

Figure 1. Sketch map of Pacaya and some nearby towns. Hachured
arcuate line indicates the caldera rim. Letter "x" refers to
MacKenney crater, "y" to the pre-1965 cone, and "z" to the 1984
spatter cone (El Hornito). Contour interval 100 m; contours around
MacKenney cone are approximate.

Figure 2. Location map showing Pacaya volcano, Guatemala City, the
international airport, major roads, and other features. Contour
lines are only shown around Pacaya (see figure 1).

Figure 3. Aerial photograph of Pacaya viewed from the NW, 10
November 1994. Vapor rising from the MacKenney summit crater can be
seen flowing down the S flank. Courtesy of Stephen O'Meara.