Breakout flood from an ignimbrite-dammed valley after the 5 ka Numazawako eruption, northeast Japan

Abstract

Research Article| September 01, 2008 Breakout flood from an ignimbrite-dammed valley after the 5 ka Numazawako eruption, northeast Japan Kyoko S. Kataoka; Kyoko S. Kataoka † 1Research Center for Natural Hazards and Disaster Recovery, Niigata University, Ikarashi 2-cho 8050, Nishi-ku, Niigata 950-2181, Japan †E-mail: [e-mail] Search for other works by this author on: GSW Google Scholar Atsushi Urabe; Atsushi Urabe 1Research Center for Natural Hazards and Disaster Recovery, Niigata University, Ikarashi 2-cho 8050, Nishi-ku, Niigata 950-2181, Japan Search for other works by this author on: GSW Google Scholar Vern Manville; Vern Manville 2GNS Science, Wairakei Research Centre, Private Bag 2000, Taupo, New Zealand Search for other works by this author on: GSW Google Scholar Atsushi Kajiyama Atsushi Kajiyama 3CTI Engineering Co., Otemae 1-2-15, Chuoku, Osaka 540-0008, Japan Search for other works by this author on: GSW Google Scholar Author and Article Information Kyoko S. Kataoka † 1Research Center for Natural Hazards and Disaster Recovery, Niigata University, Ikarashi 2-cho 8050, Nishi-ku, Niigata 950-2181, Japan Atsushi Urabe 1Research Center for Natural Hazards and Disaster Recovery, Niigata University, Ikarashi 2-cho 8050, Nishi-ku, Niigata 950-2181, Japan Vern Manville 2GNS Science, Wairakei Research Centre, Private Bag 2000, Taupo, New Zealand Atsushi Kajiyama 3CTI Engineering Co., Otemae 1-2-15, Chuoku, Osaka 540-0008, Japan †E-mail: [e-mail] Publisher: Geological Society of America Received: 27 Nov 2006 Revision Received: 03 Oct 2007 Accepted: 13 Nov 2007 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 © 2008 Geological Society of America GSA Bulletin (2008) 120 (9-10): 1233–1247. https://doi.org/10.1130/B26159.1 Article history Received: 27 Nov 2006 Revision Received: 03 Oct 2007 Accepted: 13 Nov 2007 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Kyoko S. Kataoka, Atsushi Urabe, Vern Manville, Atsushi Kajiyama; Breakout flood from an ignimbrite-dammed valley after the 5 ka Numazawako eruption, northeast Japan. GSA Bulletin 2008;; 120 (9-10): 1233–1247. doi: https://doi.org/10.1130/B26159.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Numazawa volcano in northeast Japan erupted most recently at ca. 5 ka, forming a 2-km-diameter caldera and emplacing at least 4 km3 of valley-confined ignimbrite. The ignimbrite dammed the Tadami River to a depth of >100 m, temporarily impounding >1.6 km3 of water. Overtopping of the barrier triggered breaching and catastrophic release of the dam lake. Pyroclastic material redeposited by the ensuing flood is widely distributed along the Tadami and Agano Rivers in deposits tens of meters thick as far as the coastal Niigata Plain >150 km downstream of the volcano. Evidence for damming and flooding found along the rivers includes (1) fine-grained, thinly laminated lacustrine deposits upstream of the pyroclastic blockage; (2) 30-m-thick, pumiceous debris-flow and hyperconcentrated-flow deposits that show continuous sedimentation with no major hiatus downstream of the volcano; (3) fine-grained slackwater deposits at tributary river mouths; and (4) large flood boulders that form lags on stripped ignimbrite surfaces and younger terrace surfaces, or cropping out within hyperconcentrated-flow deposits. Paleohydraulic estimation techniques indicate a peak discharge of 30,000–50,000 m3/s at the breach point. Burial of Neolithic Jomon settlements by flood and volcaniclastic aggradational deposits at distal locations indicates that such indirect volcanogenic hazards are significant, even where direct primary consequences of volcanic eruptions are minor or absent. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.