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Temporal variations of magma composition, eruption style and rate at Fuji Volcano, Japan.

Authors :
Yamamoto, Takahiro
Nakano, Shun
Ishizuka, Yoshihiro
Source :
Earth, Planets & Space; 8/26/2021, Vol. 73 Issue 1, p1-9, 9p
Publication Year :
2021

Abstract

Mt. Fuji is an active basaltic volcano near the Tokyo metropolitan area; future eruptions could thus have serious nationwide impacts. To better understand recent volcanism at Fuji Volcano, we here clarify temporal variations of eruption rate and magma composition since 5.6 ka based on time-series volumetric and geochemical data of eruptive products in a new stratigraphic sequence. Volcanic activity during the studied period consisted of (i) the emission of many lava flows that formed a new volcanic edifice between 5.6 and 3.45 ka, (ii) a period dominated by explosive events both at the summit and on the flanks of the volcano between 3.45 and 2.25 ka, and (iii) a period dominated by flank fissure eruptions since 2.25 ka. The eruption rate (dense-rock equivalent, DRE) was 3.5 km<superscript>3</superscript> DRE/kyr during the edifice-building period, decreased to 0.8 km<superscript>3</superscript> DRE/kyr during the explosive period, and then increased to 2.0 km<superscript>3</superscript> DRE/kyr since 1.5 ka. Erupted magmas were dominantly basaltic and geochemically similar through time, except for increased Sr contents and decreased Ca/Sr ratios during the explosive period. Similarly, the geochemical properties of the parental magmas did not change greatly, although the Sr contents and Ca/Sr ratios of magmas erupted during the explosive period reflect the delayed fractionation of plagioclase due to the increased water contents of the parental magmas at that time. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
13438832
Volume :
73
Issue :
1
Database :
Complementary Index
Journal :
Earth, Planets & Space
Publication Type :
Academic Journal
Accession number :
152106090
Full Text :
https://doi.org/10.1186/s40623-021-01505-1