Results 181 to 190 of about 9,726 (207)

Late Quaternary distal tephra-fall deposits in lacustrine sediments, Kenai Peninsula, Alaska

Quaternary Research, 2007
AbstractTephra-fall deposits from Cook Inlet volcanoes were detected in sediment cores from Tustumena and Paradox Lakes, Kenai Peninsula, Alaska, using magnetic susceptibility and petrography. The ages of tephra layers were estimated using 21 14C ages on macrofossils.
Christian S. de Fontaine, Darrell S. Kaufman, R. Scott Anderson, Al Werner, Christopher F. Waythomas, Thomas A. Brown   +5 more
openaire   +3 more sources

Sedimentation of tephra by volcanic plumes. Part 2: controls on thickness and grain-size variations of tephra fall deposits

Bulletin of Volcanology, 1992
A model for sedimentation from turbulent suspensions predicts that tephra concentration decreases exponentially with time in an ascending volcanic column and in the overlying umbrella cloud. For grain-size distributions typical of plinian eruptions application of the model predicts for thickness variations in good agreement with the exponential ...
Sparks, RSJ, Bursik, MI, Ablay, GJ, Thomas, RME, Carey, SN   +4 more
openaire   +4 more sources

Geochemical and geotechnical characterization of compacted air-fall tephras

2023
Presentation by University of Canterbury PhD student Shaurya ...
openaire   +1 more source

Probabilistic tephra fall simulation for the Auckland Region, New Zealand

Journal of Volcanology and Geothermal Research, 2006
Abstract The Auckland Region, New Zealand is at significant risk from tephra falls originating both from the local Auckland Volcanic Field (AVF) and several distant, large-volume centres. We use geological data and observations of historical eruptions to develop a catalogue of simulated tephra dispersal patterns for the Auckland Region, using the ...
C.R. Magill, A.W. Hurst, L.J. Hunter, R.J. Blong   +3 more
openaire   +1 more source

A model for the numerical simulation of tephra fall deposits

Journal of Volcanology and Geothermal Research, 2005
Abstract A simple semianalytical model to simulate ash dispersion and deposition produced by sustained Plinian and sub-Plinian eruption columns based on the 2D advection–dispersion equation was applied. The eruption column acts as a vertical line source with a given mass distribution and neglects the complex dynamics within the eruption column. Thus,
T. Pfeiffer, A. Costa, G. Macedonio
openaire   +1 more source

Forest fire following Holocene tephra fall

1981
The rhyolitic eruptions of the Taupo Pumice (c. 1800 B.P.) and the Kaharoa Ash (c. 700 B.P.) devastated forest close to the volcanic source. However, pollen diagrams from regions up to 150 km from the volcanic centre show that widespread fires were common over an appreciable period after both eruptions.
openaire   +1 more source

Some Effects of Tephra Falls on Buildings

1981
A survey of the volcanological literature reveals that only limited generalisations concerning the effects of volcanic bomb impacts and tephra loads on buildings can be made. By using data from a variety of other sources, however, it is possible to define the impact energies required to penetrate or damage a variety of building materials.
openaire   +1 more source

Agricultural vulnerability to tephra fall impacts.

2015
Understanding agricultural impact from tephra hazards and their causal mechanisms is vital when developing mitigation and recovery strategies. It is well documented that tephra can impact agricultural systems. However, forecasting likely impacts has been challenging and focused on creating generalised models where impacts typically increase with tephra
openaire   +2 more sources

Combined effects of wind and column mass distribution on tephra fall deposits

Environmental Software, 1990
Abstract A 2D1/2 model of volcanic ashes (tephra) dispersion, based on an analytical solution of the advection-diffusion equation, is presented. By this model the correlation between a double maximum in thickness and a punctual bimodal size distribution in plinian deposit of volcanic eruptions is outlined for the first time.
P. Armienti, G. Macedonio, M.T. Pareschi
openaire   +1 more source

A varve-based calibration of the Bridge River tephra fall

Canadian Journal of Earth Sciences, 1995
A 1 cm thick layer of Bridge River tephra is preserved in a core of varved lake sediments recovered from Hector Lake, Alberta. The varve sequence extends from the core top to well below the tephra layer and has bseen calibrated to calendar years. A varve count yields a calendar age of 2332 BP for the ash layer, with a potential error of about ±50 ...
openaire   +1 more source