James W. Vallance

Research Article| August 01, 1998 Objective delineation of lahar-inundation hazard zones Richard M. Iverson; Richard M. Iverson 1U.S. Geological Survey, Cascades Volcano Observatory, 5400 MacArthur Boulevard, Vancouver, Washington 98661 Search for other works by this author on: GSW Google Scholar Steven P. Schilling; Steven P. Schilling 1U.S. Geological Survey, Cascades Volcano Observatory, 5400 MacArthur Boulevard, Vancouver, Washington 98661 Search for other works by this author on: GSW Google Scholar James W. Vallance James W. Vallance 2Department of Civil Engineering and Applied Mechanics, McGill University, Montreal, Quebec H3A 2K6, Canada Search for other works by this author on: GSW Google Scholar Author and Article Information Richard M. Iverson 1U.S. Geological Survey, Cascades Volcano Observatory, 5400 MacArthur Boulevard, Vancouver, Washington 98661 Steven P. Schilling 1U.S. Geological Survey, Cascades Volcano Observatory, 5400 MacArthur Boulevard, Vancouver, Washington 98661 James W. Vallance 2Department of Civil Engineering and Applied Mechanics, McGill University, Montreal, Quebec H3A 2K6, Canada Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1998) 110 (8): 972–984. https://doi.org/10.1130/0016-7606(1998)110<0972:ODOLIH>2.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Richard M. Iverson, Steven P. Schilling, James W. Vallance; Objective delineation of lahar-inundation hazard zones. GSA Bulletin 1998;; 110 (8): 972–984. doi: https://doi.org/10.1130/0016-7606(1998)110<0972:ODOLIH>2.3.CO;2 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 A new method of delineating lahar hazard zones in valleys that head on volcano flanks provides a rapid, objective, reproducible alternative to traditional methods. The rationale for the method derives from scaling analyses of generic lahar paths and statistical analyses of 27 lahar paths documented at nine volcanoes. Together these analyses yield semiempirical equations that predict inundated valley cross-sectional areas (A) and planimetric areas (B) as functions of lahar volume (V). The predictive equations (A = 0.05V2/3 and B = 200 V2/3) provide all information necessary to calculate and plot inundation limits on topographic maps. By using a range of prospective lahar volumes to evaluate A and B, a range of inundation limits can be plotted for lahars of increasing volume and decreasing probability. Resulting hazard maps show graphically that lahar-inundation potentials are highest near volcanoes and along valley thalwegs, and diminish gradually as distances from volcanoes and elevations above valley floors increase. We automate hazard-zone delineation by embedding the predictive equations in a geographic information system (GIS) computer program that uses digital elevation models of topography. Lahar hazard zones computed for Mount Rainier, Washington, mimic those constructed on the basis of intensive field investigations. The computed hazard zones illustrate the potentially widespread impact of large lahars, which on average inundate planimetric areas 20 times larger than those inundated by rock avalanches of comparable volume. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Landslides reflect landscape instability that evolves over meteorological and geological timescales, and they also pose threats to people, property, and the environment. The severity of these threats depends largely on landslide speed and travel distance, which are collectively described as landslide “mobility”. To investigate causes and effects of mobility, we focus on a disastrous landslide that occurred on 22 March 2014 near Oso, Washington, USA, following a long period of abnormally wet weather. The landslide's impacts were severe because its mobility exceeded that of prior historical landslides at the site, and also exceeded that of comparable landslides elsewhere. The ∼8×106m3 landslide originated on a gently sloping (<20°) riverside bluff only 180 m high, yet it traveled across the entire ∼1 km breadth of the adjacent floodplain and spread laterally a similar distance. Seismological evidence indicates that high-speed, flowing motion of the landslide began after about 50 s of preliminary slope movement, and observational evidence supports the hypothesis that the high mobility of the landslide resulted from liquefaction of water-saturated sediment at its base. Numerical simulation of the event using a newly developed model indicates that liquefaction and high mobility can be attributed to compression- and/or shear-induced sediment contraction that was strongly dependent on initial conditions. An alternative numerical simulation indicates that the landslide would have been far less mobile if its initial porosity and water content had been only slightly lower. Sensitive dependence of landslide mobility on initial conditions has broad implications for assessment of landslide hazards.

Research Article| February 01, 1997 The Osceola Mudflow from Mount Rainier: Sedimentology and hazard implications of a huge clay-rich debris flow James W. Vallance; James W. Vallance 1U.S. Geological Survey, 5400 MacArthur Boulevard, Vancouver, Washington 98661 Search for other works by this author on: GSW Google Scholar Kevin M. Scott Kevin M. Scott 1U.S. Geological Survey, 5400 MacArthur Boulevard, Vancouver, Washington 98661 Search for other works by this author on: GSW Google Scholar Author and Article Information James W. Vallance 1U.S. Geological Survey, 5400 MacArthur Boulevard, Vancouver, Washington 98661 Kevin M. Scott 1U.S. Geological Survey, 5400 MacArthur Boulevard, Vancouver, Washington 98661 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1997) 109 (2): 143–163. https://doi.org/10.1130/0016-7606(1997)109<0143:TOMFMR>2.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation James W. Vallance, Kevin M. Scott; The Osceola Mudflow from Mount Rainier: Sedimentology and hazard implications of a huge clay-rich debris flow. GSA Bulletin 1997;; 109 (2): 143–163. doi: https://doi.org/10.1130/0016-7606(1997)109<0143:TOMFMR>2.3.CO;2 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 The 3.8 km3 Osceola Mudflow began as a water-saturated avalanche during phreatomagmatic eruptions at the summit of Mount Rainier about 5600 years ago. It filled valleys of the White River system north and northeast of Mount Rainier to depths of more than 100 m, flowed northward and westward more than 120 km, covered more than 200 km2 of the Puget Sound lowland, and extended into Puget Sound. The lahar had a velocity of ≈19 m/s and peak discharge of ≈2.5×106 m3/s, 40 to 50 km downstream, and was hydraulically dammed behind a constriction. It was coeval with the Paradise lahar, which flowed down the south side of Mount Rainier, and was probably related to it genetically.Osceola Mudflow deposits comprise three facies. The axial facies forms normally graded deposits 1.5 to 25 m thick in lowlands and valley bottoms and thinner ungraded deposits in lowlands; the valley-side facies forms ungraded deposits 0.3 to 2 m thick that drape valley slopes; and the hummocky facies, interpreted before as a separate (Greenwater) lahar, forms 2–10-m-thick deposits dotted with numerous hummocks up to 20 m high and 60 m in plan.Deposits show progressive downstream improvement in sorting, increase in sand and gravel, and decrease in clay. These downstream progressions are caused by incorporation (bulking) of better sorted gravel and sand. Normally graded axial deposits show similar trends from top to bottom because of bulking. The coarse-grained basal deposits in valley bottoms are similar to deposits near inundation limits. Normal grading in deposits is best explained by incremental aggradation of a flow wave, coarser grained at its front than at its tail.The Osceola Mudflow transformed completely from debris avalanche to clay-rich (cohesive) lahar within 2 km of its source because of the presence within the preavalanche mass of large volumes of pore water and abundant weak hydrothermally altered rock. A survey of cohesive lahars suggests that the amount of hydrothermally altered rock in the preavalanche mass determines whether a debris avalanche will transform into a cohesive debris flow or remain a largely unsaturated debris avalanche. The distinction among cohesive lahar, noncohesive lahar, and debris avalanche is important in hazard assessment because cohesive lahars spread much more widely than noncohesive lahars that travel similar distances, and travel farther and spread more widely than debris avalanches of similar volume. The Osceola Mudflow is documented here as an example of a cohesive debris flow of huge size that can be used as a model for hazard analysis of similar flows. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Research Article| February 01, 2001 New views of granular mass flows Richard M. Iverson; Richard M. Iverson 1U.S. Geological Survey, 5400 MacArthur Boulevard, Vancouver, Washington 98661, USA Search for other works by this author on: GSW Google Scholar James W. Vallance James W. Vallance 2Department of Civil Engineering and Applied Mechanics, McGill University, Montreal, Quebec H3A 2FK6, Canada Search for other works by this author on: GSW Google Scholar Author and Article Information Richard M. Iverson 1U.S. Geological Survey, 5400 MacArthur Boulevard, Vancouver, Washington 98661, USA James W. Vallance 2Department of Civil Engineering and Applied Mechanics, McGill University, Montreal, Quebec H3A 2FK6, Canada Publisher: Geological Society of America Received: 02 Jun 2000 Revision Received: 16 Oct 2000 Accepted: 25 Oct 2000 First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2001) 29 (2): 115–118. https://doi.org/10.1130/0091-7613(2001)029<0115:NVOGMF>2.0.CO;2 Article history Received: 02 Jun 2000 Revision Received: 16 Oct 2000 Accepted: 25 Oct 2000 First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Richard M. Iverson, James W. Vallance; New views of granular mass flows. Geology 2001;; 29 (2): 115–118. doi: https://doi.org/10.1130/0091-7613(2001)029<0115:NVOGMF>2.0.CO;2 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 SocietyGeology Search Advanced Search Abstract Concentrated grain-fluid mixtures in rock avalanches, debris flows, and pyroclastic flows do not behave as simple materials with fixed rheologies. Instead, rheology evolves as mixture agitation, grain concentration, and fluid-pressure change during flow initiation, transit, and deposition. Throughout a flow, however, normal forces on planes parallel to the free upper surface approximately balance the weight of the superincumbent mixture, and the Coulomb friction rule describes bulk intergranular shear stresses on such planes. Pore-fluid pressure can temporarily or locally enhance mixture mobility by reducing Coulomb friction and transferring shear stress to the fluid phase. Initial conditions, boundary conditions, and grain comminution and sorting can influence pore-fluid pressures and cause variations in flow dynamics and deposits. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.