{"id":164,"date":"2014-02-04T00:00:14","date_gmt":"2014-02-03T15:00:14","guid":{"rendered":"http:\/\/www.eri.u-tokyo.ac.jp\/_html\/en\/?p=164"},"modified":"2016-04-14T14:34:41","modified_gmt":"2016-04-14T05:34:41","slug":"eruptive-activity-of-sinabung-volcano-in-2013-and-2014","status":"publish","type":"post","link":"https:\/\/www.eri.u-tokyo.ac.jp\/en\/eq\/164\/","title":{"rendered":"Eruptive activity of Sinabung volcano in 2013 and 2014"},"content":{"rendered":"

launched:2014\/02\/04<\/p>\n

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Information are also updated on Volcanic Research Center website:
\nEruptive activity of Sinabung volcano in 2013 and 2014<\/a><\/p>\n

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Eruptive activity of Sinabung volcano in 2013 and 2014<\/b><\/p>\n

\u00a0\u00a0\u00a0\u00a0 Sinabung in the Northern Sumatra of Indonesia began its eruptive activity with phreatic events in August and September 2010. It resumed its activity in September 2013 with phreatic events. In November 2013, eruption columns stood about 5 km above the volcano. Volcanic ash issued since the middle November contained juvenile particles, and pumice fragments were ejected on to the NE flank of the volcano by the vulcanian event on 23 November 2013. Small-scale pyroclastic flows descended during the events. Though, then, the appearance of the activity looked declined, the summit of the volcano inflated and partial collapse of the summit crater outer-slope repeated. Lava appearance was confirmed in late December.<\/p>\n

\"Fig.<\/a><\/p>\n

Fig. 1. Easterly view of erupting Sinabung volcano on 25 January 2014 (S. Nakada).<\/p>\n

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\"Fig.<\/a><\/p>\n

Fig. 2. Andesite lava flow extending on the SE slope of Sinabung volcano. Taken on the early morning of 25 January (S. Nakada).<\/p>\n

Lava appeared in the summit crater grew as a dome and started its partial collapse on 30 December, generating pyroclastic flows which descended on the SE slope of the volcano. The lava dome grew to a lava flow moving to SE, repeating its partial collapse. The horizontal length of the lava flow exceeded 1 km in late January 2014.<\/p>\n

\"sinabung_fig3a\"<\/a><\/p>\n

\"Fig.<\/a><\/p>\n

Fig. 3. Relatively small pyroclastic flows on the SE slope of Sinabung volcano. Taken on 25 January 2014 (S. Nakada)<\/p>\n

Several tens collapses occurred everyday in January 2014. Relatively large collapse (pyroclastic flows) generated on 7, 11 and 21 January and 1 February. Pyroclastic flows on 1 February traveled about 4.5 km, according to newspapers, and 16 local people who invaded into the danger zone, 5 km from the summit, were involved in the flows.<\/p>\n

The present eruption at Sinabung is close to the eruption of 9 to 10th Century of this volcano in terms of both eruption site and scale (Fig. 4). It is also similar to lava-dome eruptions at Unzen, Japan, in 1991-95 and at Soufriere Hills, Montserrat, West Indies, in 1995-present, where lava dome\/flow growth associated with pyroclastic-flow events continued for several years.<\/p>\n

\"Fig.<\/a><\/p>\n

Fig. 4. Comparison of distribution of pyroclastic-flow deposits in January 2011 with that of the 9 to 10th Century eruption. Approximate location of lava flow in late January 2014 is also shown.<\/p>\n

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Composition of magma<\/b>
\nBased on the chemical analyses of pumice of the Vulcanian event on 23 November 2013 and pebbles included in pyroclastic flow event on 11 January 2014,\u00a0magma of this eruption (hornblende andesite) is similar to but a little poorer in SiO2 than the magma of the 9 to 10th Century. Even in this eruption, there is a small chemical range in erupted materials.<\/p>\n

Table 1. Chemical composition of juvenile pebbles of the 11 January 2014 pyroclastic-flow event, pumice of the 23 November 2013 vulcanian event, and the 10th\u00a0Century lava.<\/b><\/p>\n

SiO2\u00a0 TiO2\u00a0 Al2O3\u00a0 FeO*\u00a0 MnO\u00a0 MgO\u00a0 CaO\u00a0 Na2O\u00a0 K2O\u00a0 P2O5
\n11 Jan. 2014\u00a0\u00a0\u00a0\u00a0\u00a0 58.1\u00a0\u00a0 0.71\u00a0\u00a0 18.3\u00a0\u00a0 7.09\u00a0\u00a0 0.16\u00a0\u00a0 2.92\u00a0\u00a0 8.05\u00a0\u00a0 2.95\u00a0\u00a0 1.70\u00a0\u00a0 0.12
\n23 Nov. 2013\u00a0\u00a0\u00a0\u00a0 58.9\u00a0\u00a0 0.71\u00a0\u00a0 17.9\u00a0\u00a0 6.78\u00a0\u00a0 0.15\u00a0\u00a0 2.84\u00a0\u00a0 7.73\u00a0\u00a0 2.97\u00a0\u00a0 1.86\u00a0\u00a0 0.13
\nAD 800-1000\u00a0\u00a0\u00a0 \u00a059.7\u00a0\u00a0 0.71\u00a0\u00a0 17.6\u00a0\u00a0 6.58\u00a0\u00a0 0.15\u00a0\u00a0 2.86\u00a0\u00a0 7.37\u00a0\u00a0 2.99\u00a0\u00a0 1.93\u00a0\u00a0 0.13<\/p>\n

* Total iron as FeO.<\/p>\n

\u00a0\u00a0\u00a0\u00a0 Earthquake Research Institute, the University of Tokyo continues the geological inspection of the volcanic activity at Sinabung since 2010, in corporation with Kyoto and Hokkaido Universities and the Indonesian Center for Volcanology and Geological Hazard Mitigation (CVGHM). The research contains forecasting the future eruption based on geological survey and petrological monitoring of juvenile material included in volcanic ash. Kyoto University keeps monitoring of the activity with seismometer and GPS jointly with the Indonesian team.<\/p>\n

February 4, 2014(S. Nakada and M. Yoshimoto)<\/p>\n

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Geological history of Sinabung volcano<\/b><\/p>\n

Sinabung is a stratovolcano which has grown after the super eruption of 74 thousand years ago at the Toba Caldera. The volcano summit is about 2,460 m in altitude and stands about 1,200 m above the ignimbrite plateau formed by the Toba eruption. There is no record of historical eruptions, and the last magmatic eruption before 2010 occurred during 9 to 10th century, whose products are mainly pyroclastic-flow deposits, distributed in the SE slope (Iguchi et al., 2012). The present eruption which began in September 2013 is close to the sequence of the 9 to 10th Century eruption.<\/p>\n

\"sinabung_eng_fig1a\"<\/a>Basement rocks areexposed in the middle NW slope of the volcano. Older edifice is distributed in the western part, while young edifice occupies in the center\u00a0and eastern parts (Iguchi et al., 2012). Those edifices consist mainly of lava flows\/domes and pyroclastic-flow and\u00a0debris-flow deposits. No pumice fall deposits were recognized in<\/p>\n

\"Fig.<\/a><\/p>\n

Fig. 1. Index map of Sinabung volcano, Northern Sumatra, Indonesia.<\/p>\n

the edifices, suggesting that Sinabung had repeated less explosive eruptions through its history. Although several lava flows descended down to the lower slopes, relatively thick lava flows pile up on the upper slopes; where collapsed-type pyroclastic flow (block-and-ash flow) deposits are extensively distributed down to volcano foots below those lava flows. A small-scale debris avalanche deposit is distributed in the NE foot. The 9 to 10th Century pyroclastic flow deposit is widely distributed in the SE slope below the lava flows extended about 1.5 km from the summit. The travel distance of the pyroclastic flows is about 4.5 km from the summit.<\/p>\n

Rocks of Sinabung are basaltic andesite to andesite in composition (Fig. 2), and andesitic lavas contain hornblende phenocrysts. Old-stage lava is more enriched in K2O than the younger-stage lava (Iguchi et al., 2012).<\/p>\n

Event-tree showing possible eruptive events in future for Sinabung volcano is shown in Fig. 4 (Yoshimoto et al., 2013). The present eruption that began in September 2013 follows the scenario of the highest probability.<\/p>\n

This research began as a part of the SATREPS research project (Multi-disciplinary Hazard Reduction from Earthquakes and Volcanoes in Indonesia), and has continued presently in cooperation with Kyoto and Hokkaido Universities and the Indonesian Center for Volcanology and Geological Hazard Mitigation (CVGHM).<\/p>\n

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\"Fig.<\/a><\/p>\n

Fig. 2. Geologic map of Sinabung volcano (Iguchi et al., 2012).<\/p>\n

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\"Fig.<\/a><\/p>\n

Fig. 3. SiO2-K2O variation diagram for Sinabung volcano (Iguchi et al., 2012). Latest pyroclastic flow deposits = 9~10th Century eruption. Summit dome and latest spine are strongly altered hydrothermally, such that they potted away from the main chemical trend.<\/p>\n

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\"Fig.<\/a><\/p>\n

Fig. 4. Event tree of Sinabung volcano prepared in July 2013. The 2013 and 2014 eruption follows the high probability scenario in this diagram. From Yoshimoto et al. (2013).<\/p>\n

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References<\/strong><\/p>\n