Abstract
During 14–16 September 1988, a large intracaldera avalanche and an eruption of basaltic tephra and lava at Fernandina volcano, Galapagos, produced the most profound changes within the caldera since its collapse in 1968. A swarm of eight earthquakes (m b 4.7–5.5) occurred in a 14 h period on 24 February 1988 at Fernandina, and two more earthquakes of this size followed on 15 April and 20 May, respectively. On 14 September 1988, another earthquake (m b 4.6) preceded a complex series of events. A debris avalanche was generated by the failure of a fault-bounded segment of the east caldera wall, approximately 2 km long and 300 m wide. The avalanche deposit is up to 250 m thick and has an approximate volume of 0.9 km3. The avalanche rapidly displaced a preexisting lake from the southeast end of the caldera floor to the northwest end, where the water washed up against the lower part of the caldera wall, then gradually seeped into the avalanche deposit and was completely gone by mid-January 1989. An eruption began in the caldera within about 1–2 h of the earthquake, producing a vigorous tephra plume for about 12 h, then lava flows during the next two days. The eruption ended late on 16 September. Most of the eruptive activity was from vents on the caldera floor near the base of the new avalanche scar. Unequivocal relative timing of events is difficult to determine, but seismic records suggest that the avalanche may have occurred 1.6 h after the earthquake, and field relations show that lava was clearly erupted after the avalanche was emplaced. The most likely sequence of events seems to be that the 1988 feeder dike intruded upward into the east caldera wall, dislocated the unstable wall block, and triggered the avalanche. The avalanche immediately exposed the newly emplaced dike and initiated the eruption. The exact cause of the earthquakes is unknown.
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References
Acharya HK (1965) Seismicity of the Galapagos Islands and vicinity. Bull Seis Soc Am 55:609–617
Chadwick WW Jr, Howard KA (in press) The pattern of circum-ferential and radial eruptive fissures on the volcanoes of Fernandina and Isabela Islands, Galapagos. Bull Volcanol
Dieterich JH (1988) Growth and persistence of Hawaiian volcanic rift zones. J Geophys Res 93:4258–4270
Duffield WA, Stieltjes L, Varet J (1982) Huge landslide blocks in the growth of Piton de la Fournaise, La Reunion, and Kilauea volcano, Hawaii. J Volcanol Geotherm Res 12:147–160
Dziewonski AM, Ekström G, Woodhouse JH, Zwart G (1989a) Centroid-moment tensor solutions for April–June 1988. Phys Earth Planet Interiors 54:199–209
Dziewonski AM, Ekström G, Woodhouse JH, Zwart G (1989b) Centroid-moment tensor solutions for January–March 1988. Phys Earth Planet Interiors 54:22–32
Endo ET (1985) Seismotectonic framework for the southeast flank of Mauna Loa. PhD, University of Washington, Seattle
Filson J, Simkin T, Leu LK (1973) Seismicity of a caldera collapse: Galapagos Islands 1968. J Geophys Res 78:8591–8622
Fornari DJ, Moore JG, Calk L (1979) A large submarine sand and rubble flow on Kilauea Volcano, Hawaii. Jour Volcanol Geotherm Res 5:239–256
Glicken HX (1991) Rockslide-debris avalanche of May 18 1980, Mount St. Helens volcano, Washington. US Geol Surv Prof Pap 1488 (in press)
Goter SK (1988) Seismicity of Hawaii, 1962–1985. US Geol Surv Open File Rep 88-285
Kanamori H, Given JW (1982) Analysis of long-period seismic waves excited by the May 18, 1980, eruption of Mount St. Helens — a terrestrial monopole? J Geophys Res 87:5422–5432
Klein FW, Koyanagi RY, Nakata JS, Tanigawa WR (1987) The seismicity of Kilauea's magma system. US Geol Surv Prof Pap 1350:1019–1186
Lénat JF, Vincent P, Bachèlery P (1989) The off-shore continuation of an active basaltic volcano: Piton de la Fournaise (Reunion Island, Indian Ocean); structural and geomorphological interpretation from Sea Beam mapping. J Volcanol Geotherm Res 36:1–36
Lipman PW, Lockwood JP, Okamura RT, Swanson DA, Yamashita KM (1985) Ground deformation associated with the 1975 Magnitude-7.2 earthquake and resulting changes in activity of Kilauea Volcano, Hawaii. US Geol Surv Prof Pap 1276, 45 pp
Lipman PW, Normark WR, Moore JG, Wilson JB, Gutmacher CE (1988) The giant submarine Alika debris slide, Mauna Loa, Hawaii. J Geophys Res 93:4279–4299
McBirney AR, Williams H (1969) Geology and petrology of the Galapagos Islands. Geol Soc Am Mem 118, 197 pp
Moore JG, Clague DA, Holcomb RT, Lipman PW, Normark WR, Torresan ME (1989) Prodigious submarine landslides on the Hawaiian Ridge. J Geophys Res 94:17465–17484
Nakamura K (1980) Why do long rift zones develop in Hawaiian volcanoes — a possible role of thick oceanic sediments. Bull Volcanol Soc Japan 25:255–267
Siebert L (1984) Large volcanic debris avalanches: characteristics of source areas, deposits, and associated eruptions. J Volcanol Geotherm Res 22:163–197
Simkin T (1984) Geology of Galapagos Islands. In: R Perry () Galapagos. Pergamon Press, Oxford:15–41
Simkin T, Howard KA (1970) Caldera collapse in the Galapagos Islands, 1968. Science 169:429–437
Simkin T, Siebert L, McClelland L, Bridge D, Newhall C, Latter JH (1981) Volcanoes of the world. Hutchinson Ross, Stroudsburg, PA, 240 pp
Smithsonian Institution/SEAN (1988a) SEAN Bulletin 13:8, 9–10
Smithsonian Institution/SEAN (1988b) SEAN Bulletin 13:10, 14–15
Smithsonian Institution/SEAN (1989) Global Volcanism 1975–1985. Prentice Hall, Englewood Cliffs, NJ, and American Geophysical Union, Washington, DC, 657 pp
Swanson DA, Duffield WA, Fiske RS (1976) Displacement of the south flank of Kilauea Volcano: the result of forceful intrusion of magma into the rift zones. US Geol Surv Prof Pap 963, 39 pp
Tilling RI, Koyanagi RY, Holcomb RT (1975) Rockfall seismicity — correlation with field observations, Makaopuhi crater, Kilauea volcano, Hawaii. J Res US Geol Surv 3:345–361
Tilling RI, Koyanagi RY, Lipman PW, Lockwood JP, Moore JG, Swanson DA (1976) Earthquake and related catastrophic events on the island of Hawaii, November 29, 1975: preliminary report. US Geol Surv Circ 740, 33 pp
USGS (1988) Preliminary Determination of Epicenters, Monthly Listings for February, April, May, and September, National Earthquake Information Center
Voight B, Glicken H, Janda RJ, Douglass PM (1981) Catastrophic rockslide avalanche of May 18. US Geol Surv Prof Pap 1250:347–378
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Chadwick, W.W., De Roy, T. & Carrasco, A. The September 1988 intracaldera avalanche and eruption at Fernandina volcano, Galapagos Islands. Bull Volcanol 53, 276–286 (1991). https://doi.org/10.1007/BF00414524
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DOI: https://doi.org/10.1007/BF00414524