| Abstract: | Edifice deformations are reported here for the period 1988-1995 at Merapi volcano, one of the most active and dangerous volcanoes in Indonesia. The study period includes a major resumption in lava effusion in January 1992 and a major dome collapse in November 1994. The data comprise electronic distance measurements (EDM) on a summit trilateration network, slope distance changes measured to the upper flanks, and other data collected from 1988 to 1995. A major consequence of this study is the documentation of a significant 4-year period of deformation precursory to the 1992 eruption. Cross-crater strain rates accelerated from less than 3 ?? 10-6/day between 1988 and 1990 to more than 11 ?? 10-6/day just prior to the January 1992 activity, representing a general, asymmetric extension of the summit during high-level conduit pressurization. After the vent opened and effusion of lava resumed, strain occurred at a much-reduced rate of less than 2 ?? 10-6/day. EDM measurements between lower flank benchmarks and the upper edifice indicate displacements as great as l m per year over the four years before the 1992 eruption. The Gendol breach, a pronounced depression formed by the juxtaposition of old lava coule??es on the southeast flank, functioned as a major displacement discontinuity. Since 1993, movements have generally not exceeded the 95% confidence limits of the summit network. Exceptions to this include 12 cm outward movement for the northwest crater rim in 1992-1993, probably from loading by newly erupted dome lava, and movements as much as 7 cm on the south flank between November 1994 and September 1995. No short-term precursors were noted before the November 1994 lava dome collapse, but long-term adjustments of crater geometry accompanied lava dome growth in 1994. Short-term 2-cm deflation of the edifice occurred following the November 1994 dome collapse. ?? 2000 Elsevier Science B.V. All rights reserved. |
| Genre: | Article |
| ProdID: | 70022512 |
| Citation Author: | Young, K. D.; Voight, B.; Subandriyo; Sajiman; Miswanto; Casadevall, T. J. |
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| Citation End Page: | 259 |
| Citation Issue: | 1-4 |
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| Citation Language: | English |
| Citation Larger Work Title: | Journal of Volcanology and Geothermal Research |
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| Citation Number Of Pages: | 27 |
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| Citation Search Results Text: | Ground deformation at Merapi Volcano, Java, Indonesia: Distance changes, June 1988-October 1995; 2000; Article; Journal; Journal of Volcanology and Geothermal Research; Young, K. D.; Voight, B.; Subandriyo; Sajiman; Miswanto; Casadevall, T. J. |
| Citation Start Page: | 233 |
| Citation Volume: | 100 |
| Citation Year: | 2000 |
| Type: | citation/reference |
| Text: | Ground deformation at Merapi Volcano, Java, Indonesia: Distance changes, June 1988-October 1995; 2000; Article; Journal; Journal of Volcanology and Geothermal Research; Young, K. D.; Voight, B.; Subandriyo; Sajiman; Miswanto; Casadevall, T. J. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Sat, 1 Jan 2000 00:00 -0600 |
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