eruption, thanks to early warnings by scientists. I was in the south Pacific and saw
the sky was completely red due to the sun’s effects on the huge volcanic cloud.
In June 1991, the memorable eruption of Mt. Unzen in Japan took the lives of
the internationally famous volcanologists Maurice and Katia Krafft and their
colleague Harry Glicken along with forty Japanese journalists. The volcano’s
summit was fragmented during the explosion, which released a cloud of shattered
rocks and produced ashes and gas. As the coarse and denser fragments followed a
gorge curved along the flank of a previous eruption, the smaller fragments mixed
with toxic gas and ashes rose in a deadly cloud more than 10 m high. The two
volcanologists and accompanying journalists were standing about 10 m above the
gorge and were caught in the toxic cloud that suddenly enveloped the observers
along its path.
Other historical eruptions that were disastrous for the people living nearby are
the Santorini eruption in the Aegean Sea that probably was the cause of the
disappearance of the Minoan civilization in 2000 B.C., the eruption of Vesuvius in
79 B.C., and the Laki volcanic ridge in Iceland, which erupted in 1783 causing
about ten thousand deaths. In Indonesia, the Tambora volcano in 1815 and the
Krakatau volcano in 1883 killed 92,000 and 36,417 persons respectively (Fisher
et al. 1998). The eruption of Tambora released about 50 km
3 of silicic lava
(trachyandesite) reaching 43 km in altitude (Francis 1995).
The explosion of Krakatau in 1883 was heard on Rodriguez Island in the Indian
Ocean at more than 4653 km away from Java and quakes were felt on Singapore at
840 km to the west. The dust cloud released by this volcano circled around the
World. In 1928, the ‘‘child’’ of Krakatau, Anak Krakatau, emerged from the sea
and has since grown to a height of 315 m.
The 1982 eruption of El Chichon volcano in Mexico was tracked by remotesensing satellites and showed a continuous eruption cloud circling the World for
twenty days in April 1982 (Rampino and Self 1984). More recently, on May 23,
2011, the eruption of the Grimsvotn volcano in Iceland sent thousands of tons of
volcanic ash into the sky to an altitude of more than 12 miles. The cloud forced the
closure of Icelandic airspace and spread fears of a repeated eruption while global
airplane traffic was seriously interrupted for several weeks.
Volcanic clouds emitted during eruption have considerable effects on the
composition of the atmosphere. For example, ozone, which is made of 3 oxygen
atoms (O 3 ), forms a layer in the atmosphere and this is important for living
organisms because the ozone layer can absorb ultraviolet radiation from the sun.
However, ozone reacts with natural and man-made chemicals such chlorofluorocarbon (Halmer 2005). The sulfur bearing oxides, sulfates and chlorate emissions
released during volcanic eruptions form complexes with the oxygen of the
atmosphere and are also responsible for the ozone layer’s destruction. Following
the monitoring of the eruption of Pinatubo in the Philippines from 1991 up to
2005, a considerable increase in the chlorine content in the stratosphere has been
noted. (Halmer 2005) This could have been another cause of the ozone’s
destruction during that period. Whether the observed increase of chlorine in the
Historical Eruptions
137
the sky was completely red due to the sun’s effects on the huge volcanic cloud.
In June 1991, the memorable eruption of Mt. Unzen in Japan took the lives of
the internationally famous volcanologists Maurice and Katia Krafft and their
colleague Harry Glicken along with forty Japanese journalists. The volcano’s
summit was fragmented during the explosion, which released a cloud of shattered
rocks and produced ashes and gas. As the coarse and denser fragments followed a
gorge curved along the flank of a previous eruption, the smaller fragments mixed
with toxic gas and ashes rose in a deadly cloud more than 10 m high. The two
volcanologists and accompanying journalists were standing about 10 m above the
gorge and were caught in the toxic cloud that suddenly enveloped the observers
along its path.
Other historical eruptions that were disastrous for the people living nearby are
the Santorini eruption in the Aegean Sea that probably was the cause of the
disappearance of the Minoan civilization in 2000 B.C., the eruption of Vesuvius in
79 B.C., and the Laki volcanic ridge in Iceland, which erupted in 1783 causing
about ten thousand deaths. In Indonesia, the Tambora volcano in 1815 and the
Krakatau volcano in 1883 killed 92,000 and 36,417 persons respectively (Fisher
et al. 1998). The eruption of Tambora released about 50 km
3 of silicic lava
(trachyandesite) reaching 43 km in altitude (Francis 1995).
The explosion of Krakatau in 1883 was heard on Rodriguez Island in the Indian
Ocean at more than 4653 km away from Java and quakes were felt on Singapore at
840 km to the west. The dust cloud released by this volcano circled around the
World. In 1928, the ‘‘child’’ of Krakatau, Anak Krakatau, emerged from the sea
and has since grown to a height of 315 m.
The 1982 eruption of El Chichon volcano in Mexico was tracked by remotesensing satellites and showed a continuous eruption cloud circling the World for
twenty days in April 1982 (Rampino and Self 1984). More recently, on May 23,
2011, the eruption of the Grimsvotn volcano in Iceland sent thousands of tons of
volcanic ash into the sky to an altitude of more than 12 miles. The cloud forced the
closure of Icelandic airspace and spread fears of a repeated eruption while global
airplane traffic was seriously interrupted for several weeks.
Volcanic clouds emitted during eruption have considerable effects on the
composition of the atmosphere. For example, ozone, which is made of 3 oxygen
atoms (O 3 ), forms a layer in the atmosphere and this is important for living
organisms because the ozone layer can absorb ultraviolet radiation from the sun.
However, ozone reacts with natural and man-made chemicals such chlorofluorocarbon (Halmer 2005). The sulfur bearing oxides, sulfates and chlorate emissions
released during volcanic eruptions form complexes with the oxygen of the
atmosphere and are also responsible for the ozone layer’s destruction. Following
the monitoring of the eruption of Pinatubo in the Philippines from 1991 up to
2005, a considerable increase in the chlorine content in the stratosphere has been
noted. (Halmer 2005) This could have been another cause of the ozone’s
destruction during that period. Whether the observed increase of chlorine in the
Historical Eruptions
137