Lahars: Volcano-Hydrologic Events and Deposition in the Debris Flow—hyperconcentrated Flow Continuum

Smith, Gary A.; Lowe, Donald R.

doi:10.2110/pec.91.45.0059

Cited by 223 publications

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“…Stream flows are muddy water streams with a sediment concentration below 20% in volume. Lahars however, can be further separated according to their sediment concentration: into hyperconcentrated flows between 20 and 50-60% in volume, and into debris flows if the volumetric sediment concentration is higher than 50-60% (Pierson and Scott, 1985;Pierson, 1986;Smith and Lowe, 1991;Coussot and Meunier, 1996;Vallance, 2000;Lavigne and Thouret, 2002). The lahars simulated in this study represent debris flow types with sediment concentrations similar to the observed ice-melt-triggered lahars on Popocatépetl in City, the study area and Puebla is derived from SRTM3 elevation model.…”

Section: Introductionmentioning

confidence: 80%

Assessing lahars from ice-capped volcanoes using ASTER satellite data, the SRTM DTM and two different flow models: case study on Iztaccíhuatl (Central Mexico)

Schneider

Granados

Huggel

et al. 2008

Nat. Hazards Earth Syst. Sci.

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Abstract. Lahars frequently affect the slopes of ice-capped volcanoes. They can be triggered by volcano-ice interactions during eruptions but also by processes such as intense precipitation or by outbursts of glacial water bodies not directly related to eruptive activity. We use remote sensing, GIS and lahar models in combination with ground observations for an initial lahar hazard assessment on Iztaccíhuatl volcano (5230 m a.s.l.), considering also possible future developments of the glaciers on the volcano. Observations of the glacial extent are important for estimations of future hazard scenarios, especially in a rapidly changing tropical glacial environment. In this study, analysis of the glaciers on Iztaccíhuatl shows a dramatic retreat during the last 150 years: the glaciated area in 2007 corresponds to only 4% of the one in 1850 AD and the glaciers are expected to survive no later than the year 2020. Most of the glacial retreat is considered to be related to climate change but in-situ observations suggest also that geo-and hydrothermal heat flow at the summit-crater area can not be ruled out, as emphasized by fumarolic activity documented in a former study. However, development of crater lakes and englacial water reservoirs are supposed to be a more realistic scenario for lahar generation than sudden ice melting by rigorous volcano-ice interaction. Model calculations show that possible outburst floods have to be larger than ∼5×10 5 m 3 or to achieve an H/L ratio (Height/runout Length) of 0.2 and lower in order to reach the populated lower flanks. This threshold volume equals 2.4% melted ice of Iztaccíhuatl's total ice volume in 2007, assuming 40% water and 60% volumetric debris content of a potential lahar. The model sensitivity analysis reveals important effects of the generic type of the Digital Terrain ModelCorrespondence to: D. Schneider (demian.schneider@geo.uzh.ch) (DTM) used on the results. As a consequence, the predicted affected areas can vary significantly. For such hazard zonation, we therefore suggest the use of different types of DTMs and flow models, followed by a careful comparison and interpretation of the results.

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Section: Introductionmentioning

confidence: 80%

Assessing lahars from ice-capped volcanoes using ASTER satellite data, the SRTM DTM and two different flow models: case study on Iztaccíhuatl (Central Mexico)

Schneider

Granados

Huggel

et al. 2008

Nat. Hazards Earth Syst. Sci.

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“…In general, lahars can be divided into those that are a direct result of eruptive activity and those that are not temporally related to eruptions (Smith & Lowe 1991). The former may be generated by eruption-induced sector collapses, eruptions through crater lakes, melting of debris-laden snow and ice by hot pyroclastic materials, mixing of pyroclastic flows or other large volumes of volcanic debris with water, and evolution by gravity segregation within pyroclastic surges (Janda et al 1981;Boudon et al 1987;Siebert et al 1987;Major & Newhall 1989;Vallance & Scott 1997;Mothes et al 1998;Waythomas 1999).…”

Section: Triggering Mechanisms and Sediment Sources For Laharsmentioning

confidence: 99%

Late Quaternary constructional history of the southeastern Ruapehu ring plain, New Zealand

Donoghue

Neall

2001

New Zealand Journal of Geology and Geophysics

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“…7). Type A deposits are characteristic of hyperconcentrated flow that is transitional to dilute debris flow, based on particle-size distributions and sedimentary structures (Pierson and Scott 1985Smith 1986, Scott 1988Smith and Lowe 1991;Pierson 2005). The type A deposit at the base of the Bluff Section has a hard consistence and may have been emplaced by fully formed debris flow.…”

Section: Interpretation Of Deposits and The Lahar-flood Eventmentioning

confidence: 99%

“…The type A deposit at the base of the Bluff Section has a hard consistence and may have been emplaced by fully formed debris flow. Type B deposits are characteristic of both dilute hyperconcentrated flow (Smith 1986;Smith and Lowe 1991;Pierson 2005) and muddy streamflow under upper-flow-regime (generally supercritical turbulent flow) conditions (Harms et al 1963;Simons et al 1965;McKee et al 1967). The high fines contents and poor sorting of the deposits indicate that emplacement occurred by a flow close to the transition between hyperconcentrated flow and muddy streamflow.…”

Section: Interpretation Of Deposits and The Lahar-flood Eventmentioning

confidence: 99%

Acute sedimentation response to rainfall following the explosive phase of the 2008–2009 eruption of Chaitén volcano, Chile

Pierson

Major

Amigo³

et al. 2013

Bull Volcanol

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The 10-day explosive phase at the start of the 2008-2009 eruption of Chaitén volcano in southern Chile (42.83°S, 72.65°W) blanketed the steep, rain-forestcloaked, 77-km 2 Chaitén River drainage basin with 3 to >100 cm of tephra; predominantly fine to extremely fine rhyolitic ash fell during the latter half of the explosive phase. Rain falling on this ash blanket within days of cessation of major explosive activity generated a hyperconcentratedflow lahar, followed closely by a complex, multi-day, muddy flood (streamflow bordering on dilute hyperconcentrated flow). Sediment mobilized in this lahar-flood event filled the Chaitén River channel with up to 7 m of sediment, buried the town of Chaitén (10 km downstream of the volcano) in up to 3 m of sediment, and caused the lower 3 km of the channel to avulse through the town. Although neither the nature nor rate of the sedimentation response is unprecedented, they are unusual in several ways: (1) (3) The volume of sediment eroded from hillslopes and delivered to the Chaitén River channel was at least 3-8×10 6 m 3 -roughly 15-40 % of the minimum tephra volume that mantled the Chaitén River drainage basin. (4) The acute sedimentation response to rainfall appears to have been due to the thickness and fineness of the ash blanket (inhibiting infiltration of rain) and the steepness of the basin's hillslopes. Other possible factors such as the prior formation of an ash crust, development of a hydrophobic surface layer, or large-scale destruction of rain-intercepting vegetation did not play a role.

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Lahars: Volcano-Hydrologic Events and Deposition in the Debris Flow—hyperconcentrated Flow Continuum

Cited by 223 publications

References 0 publications

Assessing lahars from ice-capped volcanoes using ASTER satellite data, the SRTM DTM and two different flow models: case study on Iztaccíhuatl (Central Mexico)

Assessing lahars from ice-capped volcanoes using ASTER satellite data, the SRTM DTM and two different flow models: case study on Iztaccíhuatl (Central Mexico)

Late Quaternary constructional history of the southeastern Ruapehu ring plain, New Zealand

Acute sedimentation response to rainfall following the explosive phase of the 2008–2009 eruption of Chaitén volcano, Chile

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