Smithsonian Institution
Global Volcanism Network Bulletin v. 20, no. 1, January 1995

Fernandina (Galapagos Islands)  Lava escapes on SW flank and flows
       5 km to enter the ocean

Galapagos Islands, Ecuador
0.37 S, 91.55 W; summit elev. 1,495 m
All times are local (= GMT - 6 hours)

Fernandina, the most active Galapagos volcano, erupted from a
fissure on its outer flank (figure 1). The last flank eruption, in
1968, was followed by a 350-m collapse of the central caldera
floor, and the eight eruptions since then have all been within the
caldera or on its rim. The last intracaldera eruption took place in
1991 (Bulletin v. 16, nos. 3-4).

On the evening of 25 January distant observers saw a red glow over
Fernandina. Closer inspection a day and a half later revealed lava
erupting from a radial fissure on the island's SW flank and flowing
~5 km to the ocean (figure 1). At the ocean entry, lava constructed
a delta and, although reports suggested a possible decrease in lava
output after 13 February, the eruption continued as of

According to Jim Stimac, the eruption was first sighted at about
1930 on 25 January, when Lenin Cruz, on a fishing boat 140 km E of
Fernandina, noticed a red-orange glow on the horizon lingering
after sunset. About 50 minutes later, volcanologists Stimac and
Fraser Goff also noticed the glow from their campsite on the NW rim
of Sierra Negra volcano, ~65 km SE. By 2040 they saw glow both from
a rising plume over the SW flank and from the summit caldera, which
had just cleared of clouds. The glow persisted until dawn. At 0630
the next morning they could see a 4-km-high plume rising from the
SW flank of Fernandina. On this and following days the eruption was
also witnessed from fishing boats and official Ecuadorian vessels.

As Stimac and others approached Fernandina on the morning of 27
January, they saw two distinct plumes from gases rising over the
fissure vent, and from steam over the ocean entry. The two plumes
coalesced, rose 3-4 km, and were blown to the W as a white plume.
A red-brown haze layer was visible downwind of the vertical plume,
and a bluish color was seen above the fissure. After sunset on 27
January, the fissure, a sinuous lava flow, and the ocean entry were
more clearly visible. Lava flowing in a narrow active channel near
the vent traveled at 3-5 m/sec. The larger velocity was similar to
values estimated later from videos. Stimac made an
order-of-magnitude lava output estimate, based on the larger
velocity and a 10-m width by a 3-m depth, of about 1.3 x 10^7

On both the evening of 28 January and the morning of 29 January the
fissure vent was several hundred meters in length, with three
distinct fountains. The highest fountaining issued from the upper
two vents, and the highest-thrown bombs took 3-5 seconds to fall,
indicative of 45-125 m fountain heights. The upper fountain
produced the finest tephra (most vesicles, highest proportion of
vesicles to glass) and probably had the highest gas-to-lava ratio.
The middle fountain produced larger bombs. Whereas the upper two
fountains were vertical, the lowest vent sent material laterally
downslope. Tephra were found as far as 1 km from the vent; near the
fissure, they were generally <1 cm in diameter. The tephra
consisted of amber-brown vesicular glass with 5-10% plagioclase

An asymmetric spatter-cone several meters high had grown around the
main fissure vent by sunrise on 28 January. By the next morning it
had reached 20-30 m high. Clear weather on 29 January unveiled at
least two other recently active vents, burnt vegetation, and fresh
lava located higher on the SW flank. These observations, combined
with those of 25 January, suggested to Stimac that the eruption
began inside the caldera, but shifted almost immediately to the
radial flank fissures. The caldera, however, has not been visited
since the eruption began. Stimac left Fernandina on 29 January, but
he saw activity at the main vent episodically, as conditions
permitted, from Alcedo volcano (~45 km E) until he left the islands
on 14 February.

Within about a kilometer of the main vent and lava channel, Palo
Santo trees were felled or broken. Tui De Roy described them as
broken by "violent turbulence" and noted that they had fallen in
seemingly random directions around what she inferred to be the
early vents.

The translucent, bluish gas plume above the fissure was typically
a few hundred meters wide and it rose 100-500 m high before forming
turbulent steam clouds. Observers smelled no sulfur gases, but an
acrid smell was attributed to unseen, but suspected, burned
vegetation. Falling rain irritated eyes and may have also damaged

Godfrey Merlen's report on the eruption follows. "Although some new
lava fields have been created, the eruption has settled into a
pattern with fountaining lava (30-200 m) forming scoria ridges
alongside its fissure. It seems that initially the active fissure
extended for about 1.5 km, but later lava extrusion was restricted
to about 400 m (29 January). However, a film taken on 2 February
seems to show an increase in the length of the erupting fissure. A
river of lava about 100 m wide is seen flowing to the sea, about 5
km away, where new land is slowly being formed. The front entering
the sea is about 800-m wide."

At the ocean entry, the lava had several active channels, and
several that were recently abandoned. Near the ocean entry,
observers identified 15 fish species of dead fish, including some
that live at moderate depths. The normally dark-green seawater
abruptly changed to yellow-green at a distance of ~900 m from the
ocean entry. Ambient sea surface temperature was ~25 deg C at
distance from the eruption, but in the yellow-green area it reached
32 deg C. On 28 January, ponded lava drained rapidly into the sea.
At a location 200 m out from the ocean entry, steam rose and the
sea-surface temperature exceeded the thermometer's range (>60 deg
C). Cold surface water was also detected (19.6 deg C, or ~5 deg C
below ambient); it may have risen from depth when displaced by
encroaching lava.

Tui De Roy noted that the eruption appeared to change after 13
February, when flow-filled channels caused new lava to spread out
into smaller lobes with less of a trough-shaped morphology. She
also noted that the amber-colored, W-directed plume was visible for
tens of kilometers.

Although the eruption has yet to be imaged from space, the eruption
has been documented on film by local and visiting scientists, and
a Japanese public television crew. The TV crew's producer,
Hiromichi Iwasaki, described a 1.5-km radius of discolored water
around the entry, and rain due to condensed steam. Tui De Roy
reported that the eruption took a considerable toll on wildlife, as
many fish died and this attracted seabirds who dove into the heated
waters and were scalded to death.

The eruption followed an increase in seismicity in and near the
western Galapagos. A moderate earthquake (mb 5.1) was recorded at
1811 on 14 December. Another mb 5.1 at 1330 on 11 January followed
five smaller events the previous day on the transform fault ~200 km
NNE of Fernandina. We have also received reports of local
earthquakes felt on Alcedo volcano (~45 km E).

Fernandina also erupted in 1991, 1988, 1984, 1981 (+- 1), and 17-18
other times in a historical record going back as far as 1813. Most
of these eruptions were of short duration and located in or near
the summit caldera.

Information Contacts: Jim Stimac, Los Alamos National Laboratory,
EES 1, Geology-Geochemistry, Los Alamos, NM, 87545 USA; Godfrey
Merlen, skipper of motor vessel "Ratty," Fundacion Charles Darwin
Para Las Islas Galapagos, Estacion Cientifica Charles Darwin; 
Hiromichi Iwasaki, Producer, Science Programmes Division, Nippon
Hoso Kyokai (Japan Broadcasting Corporation), Jinnan, Shibuya-ku,
Tokyo, Japan; Tui De Roy, Patons Rock Beach, Takaka, Golden Bay,
New Zealand; NEIC (see Earthquakes).

Figure 1. Sketch map of Fernandina showing preliminary locations of
the ocean entry and main vent. Some estimates suggest the main vent
was closer to the sea, only 2 km inland. The index map is
incomplete in its portrayal of both volcanoes and islands of the