Because of numerous technical difficulties, the breach was smaller than originally planned, and only 20% of the flow was diverted out of the main channel.. Even though lava overtopped th
Trang 1lead the flow into a diversion channel The levee was
reduced to only a few metres thick, and 400 kg of
dynamite were set in the hot wall of the levee Because
of numerous technical difficulties, the breach was
smaller than originally planned, and only 20% of the
flow was diverted out of the main channel Next,
people tried to construct a rubble barrier about 10 m
high, 30 m wide, and 400 m long along the western
margin of the flow Even though lava overtopped the
first barrier, more barriers were formed and finally
they succeeded in preventing lateral spreading of the
flow field into developed areas
Heimaey (Iceland)
The 1973 eruption on the island of Heimaey is a
famous example of fighting a lava flow by cooling it
with water A fissure eruption began in January from
a 2 km long fissure across the island in the vicinity of
the centre of the town of Vestmannaeyjar, one of
Iceland’s major fishing ports Lava flow from the
vent began to threaten the town and the port As
the flow advanced to the north and east, the mouth
of the port began to be buried by lava A second large
lava flow moved north-west on the west side of the
main flow and had covered many houses by the end of
March By early May, some 300 buildings had been
engulfed by lava flows or gutted by fire To prevent
the advance of the lava and save the town and port,
people sprayed seawater onto the moving lava during
the eruption More than 30 km of water pipes and
43 pumps were used to deliver seawater at up to
1 m3s 1 A total of 6 000 000 m3of water was poured
onto the lava The front of the lava flow was
solidi-fied by the cooling effect of the water and it stopped
moving The eruption ended in July that year and the
port was saved After the eruption, people made a
great effort to remove the lava and tephra from the
centre of the city
See Also
Engineering Geology: Natural and Anthropogenic Geo-hazards Igneous Processes Large Igneous Prov-inces Mantle Plumes and Hot Spots Plate Tectonics Pyroclastics Tectonics: Mid-Ocean Ridges Volcanoes
Further Reading
Bardintzeff JM and McBirney AR (2000) Volcanology, 2nd edn Sudbury, MA: Jones & Bartlett Publishers
Cas RAF and Wright JV (1987) Volcanic Successions: Modern and Ancient London: Chapman & Hall Decker R and Decker B (1989) Volcanoes: Revised and Updated Edition New York: WH Freeman and Company
Decker RW, Wright TL, and Stauffer PH (eds.) (1987) Volcanism in Hawaii Professional Paper 1350 US Geo logical Survey
Fink JH (ed.) (1990) Lava Flows and Domes: Emplace ment Mechanisms and Hazard Implications IAVCEI Proceedings in Volcanology 2 New York: Springer Verlag
Green J and Short NM (1971) Volcanic Landforms and Surface Features A Photographic Atlas and Glossary New York: Springer Verlag
Hall A (1996) Igneous Petrology, 2nd edn London: Long man Group Limited
Macdonald GA, Abbot AT, and Peterson FL (1990) Volca noes in the Sea: The Geology of Hawaii, 2nd edn Honolulu: University of Hawaii Press
Schminke HU (2003) Volcanism New York: Springer Verlag
Sigurdsson H, Houghton B, McNutt ST, Rymer H, and Stix J (eds.) (2000) Encyclopedia of Volcanology San Diego: Academic Press
Wright T, Takahashi TJ, and Griggs JD (1992) Hawaii Volcano Watch: A Pictorial History, 1779 1991 Hono lulu: University of Hawaii Press and Hawaii National History Association
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