Study of the groundmass textures of volcanic products from Asama volcano and its implications for prediction of eruption.
| Project/Area Number |
17540435
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Geology
|
|---|
| Research Institution | SHINSHU UNIVERSITY |
|---|
Principal Investigator |
MIYAKE Yasuyuki Shinshu University, Fac.Science, Professor, 理学部, 教授 (70200144)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
HARAYAMA Satoru Shinshu University, Fac.Science, Professor, 理学部, 教授 (60293536)
MAKINO Kuniaki Shinshu University, Fac.Science, Associate Professor, 理学部, 助教授 (30242712)
|
|---|
| Project Period (FY) |
2005 – 2006
|
| Project Status |
Completed (Fiscal Year 2006)
|
| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2006: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 2005: ¥3,400,000 (Direct Cost: ¥3,400,000)
|
|---|
| Keywords | Asama volcano / vulcanian eruption / pumice / scoria / volcanic bomb / water content / crystal size distribution / excess pressure / 津間火山 |
|---|
| Research Abstract |
Asama volcano, central Japan was active during September to December, 2004. Among its several eruptions, vulcanian eruptions of Sept 1st. and Sept 23rd. were relatively intensive. We described the ascent and crystallization process of the magma during these three weeks as follows. Before Sept. 1st, a column of new magma had risen into the pre existing andesite body beneath the crater floor. On Sept.1st, the built up gas pressure surpassed the tensile strength of the andesite body to result in a vulcanian eruption. This eruption provided fragments of the pre-Sept.1st andesite, along with smaller amounts of the essential breadcrust pumices, the glass of which contain 0.4-0.8wt.% of water based on the infrared absorption spectra measurement. Because the cap rock had disappeared, the magma could uplift, upper portion of which effused and made a dome inside the crater. It in turn became a cap rock for the succeeding magma. On Sept. 23rd, next vulcanian eruption took place, the ejecta of this eruption consisting of the lithic fragments and the essential scoria with 0.1wt% water.
The textural and chemical analyses of the essential materials ; pumice of Sept.1st and scoria of Sept 23rd, reveal the crystallization process in a chamber-vent system. Following the crystallization of phenocrysts in a deeper magma chamber, two crystallization stages are preserved in crystal size distribution of microlites both in the pumice and scoria. First stage : Magma left the chamber and rose through complex path-steps with ever increasing nucleation. Second stage : In a shallower part in the vent, numerous microlites precipitated rapidly under a high undercooling condition. The similarity between the both CSD patterns implies that their magma had a common ascent history, although groundmass in the scoria has lower crystallinity than that in the pumice, suggesting that the scoria magma stood lower in the magma column.
|
Report
(3 results)
Research Products
(13 results)
-
-
-
-
-
-
-
-
-
[Journal Article] On the essential ejecta of the September 2004 eruptions of the Asama volcano, central Japan2005
Author(s)
Miyake, Y., Takahashi, K., Tsugane, T., Makino, K., Kakuzen, H, Nishiki, K., Fukui, T., Shinshu University Research Group for Asama 04 Eruptions
-
Journal Title
Bul. Volcanol. Soc. Japan vol.50,no.5
Pages: 333-346
Description
「研究成果報告書概要(欧文)」より
Related Report
-
[Journal Article] On the public attitudes to the volcanic hazards and hazard map after the publication of Yakedake volcanic hazard map2005
Author(s)
Itoh, H., Wakiyama, K., Miyake, Y., Hayashi, S., Furukawa, J., Inoue, S.
-
Journal Title
Bul. Volcanol. Soc. Japan vol.50,no.6
Pages: 427-440
NAID
Description
「研究成果報告書概要(欧文)」より
Related Report
-
-
-
