Post-eruption sediment budget of a small catchment on the Miyakejima volcano, Japan
Post-eruption sediment budget of a small catchment on the Miyakejima volcano, Japan
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日本三宅岛火山小流域喷发后沉积物预算
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
H. Nagura
中科院分区：
文献类型：
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作者：
Satoshi Tagata;T. Yamakoshi;Y. Doi;K. Sasahara;Haruo Nishimoto;H. Nagura
2000年，三宅岛火山爆发，释放出大量的细火山灰。麻风的沉积促进了侵蚀过程。在靠近山顶的上斜坡上，沟壑迅速发育，包括本研究感兴趣的斜坡。为了了解火山喷发后的侵蚀过程，进行了航空摄影测量和航空激光扫描测量。对调查数据的补充分析显示：(a)侵蚀沉积物的总量超过了2000年火山喷发沉积的火山泥。据估计，自火山喷发以来的四年中，被侵蚀的面积约为47万立方米，而火山灰的沉积面积约为37万立方米。(b)沟蚀是研究边坡的主要侵蚀过程。它至少占总侵蚀量的87%，细沟侵蚀和板状侵蚀分别占5%和8%。(c)火山喷发几个月后，沟壑侵蚀几乎停止。(d)沟壑通过新地幔被侵蚀到相当深的地方。几乎80%的沟蚀沉积物是原始土壤。(e)在三宅岛火山上斜坡观测到的爆发后侵蚀率几乎是以往研究报告中最大的。这不仅是因为三宅岛火山的山是由可侵蚀的沉积物组成的，而且还因为很少有研究记录了火山最上面的斜坡在侵蚀的早期阶段的侵蚀速率。
The Miyakejima volcano erupted in 2000, emitting a massive quantity of fine tephra. The deposition of the tephra encouraged erosion processes. Gullies rapidly developed in the upper slope close to the peak, including the slope of interest in this study. To understand post-eruption erosion processes, an aerial photograph survey and airborne laser scanning survey were conducted. The complementary analysis of the survey data revealed the following: (a) The total volume of the eroded sediment exceeds that of the tephra deposited by the 2000 eruption. The amount eroded in the four years since the eruption was estimated at 470 000 m 3 while the deposition of tephra is estimated at about 370 000 m 3 . (b) Gully erosion was the dominant process on the study slope. It accounted for at least 87% of the total erosion, while rill and sheet erosion represented 5 and 8%, respectively. (c) Gully erosion almost stopped several months after the eruption. (d) The gullies eroded to considerable depths through the new tephra mantle. Almost 80% of the gully-eroded sediment was original soil. (e) The post-eruption erosion rate observed on the upper slope of the Miyakejima volcano was almost the largest of the rates reported in previous studies. This occurs not only because the mountain of the Miyakejima volcano consists of erodible sediment, but also because few studies have documented the erosion rate of the uppermost slope of a volcano in the very early stages of erosion.