The mechanism of unsaturated flow through a volcanic ash layer under humid climatic conditions

1988 ◽  
Vol 2 (1) ◽  
pp. 43-59 ◽  
Author(s):  
Jun Shimada
Keyword(s):  
Volcanic Ash ◽  
Unsaturated Flow ◽  
Climatic Conditions ◽  
Ash Layer ◽  
Flow Through

scholarly journals Volcanic ash layer depth: Processes and mechanisms

2015 ◽  
Vol 42 (2) ◽  
pp. 637-645 ◽  
Author(s):  
H. F. Dacre ◽  
A. L. M. Grant ◽  
N. J. Harvey ◽  
D. J. Thomson ◽  
H. N. Webster ◽  
...  
Keyword(s):  
Volcanic Ash ◽  
Layer Depth ◽  
Ash Layer

scholarly journals A Study on Appling the Expert System for Correlating Volcanic Ash Layer

1987 ◽  
Vol 1987 (12) ◽  
pp. 105-110
Author(s):  
Kaichiro YAMAMOTO ◽  
Younosuke NAKAGAWA
Keyword(s):  
Expert System ◽  
Volcanic Ash ◽  
Ash Layer

scholarly journals Identification and correlation of distal tephra layers in deep-sea sediment cores, Scotia Sea, Antarctica

1998 ◽  
Vol 27 ◽  
pp. 285-289 ◽  
Author(s):  
S. G. Moreton ◽  
J. L. Smellie
Keyword(s):  
Deep Sea ◽  
Volcanic Ash ◽  
Sediment Cores ◽  
Quaternary Deposits ◽  
Deep Sea Sediment ◽  
Scotia Sea ◽  
Ash Layer ◽  
Tephra Layers ◽  
Major Oxide ◽  
Water Depths

Quaternary deposits in six sediment cores from the Scotia Sea, Antarctica, were examined for the presence of volcanic ash layers. The cores were recovered from water depths of 3369-4025 m. Altogether, 23 ash layers were found, 18 of which have been investigated by electron-probe microanalysis. Deception Island is identified as the source of all the ash layers analyzed. The upper ash layer in each core can be correlated across all six cores, over a distance of -100 km, on the basis of its unusual bimodal composition, major oxide geochemistry and stratigraphie position. Two other ash layers can also be correlated between several of the cores.

scholarly journals Quantifying uncertainties in marine volcanic ash layer records from ocean drilling cores

2014 ◽  
Vol 357 ◽  
pp. 218-224 ◽  
Author(s):  
Sue H. Mahony ◽  
R.S.J. Sparks ◽  
Nick H. Barnard
Keyword(s):  
Volcanic Ash ◽  
Ocean Drilling ◽  
Ash Layer

scholarly journals Experimental Study of Rainfall Infiltration in an Analog Fracture-matrix System

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Zhen Zhong ◽  
Huicai Gao ◽  
Yunjin Hu
Keyword(s):  
Unsaturated Flow ◽  
Rainfall Infiltration ◽  
Combination Method ◽  
Matrix System ◽  
Capillary Barrier ◽  
Hydraulic Behaviour ◽  
Experimental Apparatus ◽  
Matrix Interactions ◽  
The Matrix ◽  
Flow Through

In this study, an experimental apparatus was developed to investigate unsaturated infiltration in an analog fracture-matrix system. Fracture and adjacent matrix is simulated by sands with various particle sizes. Four rainfall infiltration experiments were performed on the analog fracture-matrix system at a constant rainfall rate of 100 mm/h. The process of rainfall infiltration is measured by a combination method of tensiometers and quick moisture apparatus. The measured results reveal that fracture-matrix interactions certainly exert influences on the hydraulic behaviour of unsaturated fractured matrix, and the fluid flow mainly infiltrates along the nonuniform paths within the matrix. Moreover, it is observed that the influences are greater when using a coarser sand to mimic the fracture. Specifically, the wetting phase in the matrix moves faster than that in the fracture; the fracture, therefore, acts as a vertical capillary barrier, but there exists lateral water exchange from the matrix to the fracture. Overall, this study has demonstrated the importance of fracture/matrix interactions, which should be considered when dealing with unsaturated flow through permeable matrices.

scholarly journals Volcanic ash, victims, and tsunami debris from the Late Bronze Age Thera eruption discovered at Çeşme-Bağlararası (Turkey)

2021 ◽  
Vol 119 (1) ◽  
pp. e2114213118
Author(s):  
Vasıf Şahoğlu ◽  
Johannes H. Sterba ◽  
Timor Katz ◽  
Ümit Çayır ◽  
Ümit Gündoğan ◽  
...  
Keyword(s):  
Bronze Age ◽  
Volcanic Ash ◽  
Thick Layer ◽  
Archaeological Site ◽  
Tsunami Deposit ◽  
Late Bronze Age ◽  
Mediterranean Studies ◽  
Ash Layer ◽  
Time Capsule ◽  
Thera Eruption

The Late Bronze Age Thera eruption was one of the largest natural disasters witnessed in human history. Its impact, consequences, and timing have dominated the discourse of ancient Mediterranean studies for nearly a century. Despite the eruption’s high intensity (Volcanic Explosivity Index 7; Dense Rock Equivalent of 78 to 86 km) [T. H. Druitt, F. W. McCoy, G. E. Vougioukalakis, Elements 15, 185–190 (2019)] and tsunami-generating capabilities [K. Minoura et al., Geology 28, 59–62 (2000)], few tsunami deposits are reported. In contrast, descriptions of pumice, ash, and tephra deposits are widely published. This mismatch may be an artifact of interpretive capabilities, given how rapidly tsunami sedimentology has advanced in recent years. A well-preserved volcanic ash layer and chaotic destruction horizon were identified in stratified deposits at Çeşme-Bağlararası, a western Anatolian/Aegean coastal archaeological site. To interpret these deposits, archaeological and sedimentological analysis (X-ray fluorescence spectroscopy instrumental neutron activation analysis, granulometry, micropaleontology, and radiocarbon dating) were performed. According to the results, the archaeological site was hit by a series of strong tsunamis that caused damage and erosion, leaving behind a thick layer of debris, distinguishable by its physical, biological, and chemical signature. An articulated human and dog skeleton discovered within the tsunami debris are in situ victims related to the Late Bronze Age Thera eruption event. Calibrated radiocarbon ages from well-constrained, short-lived organics from within the tsunami deposit constrain the event to no earlier than 1612 BCE. The deposit provides a time capsule that demonstrates the nature, enormity, and expansive geographic extent of this catastrophic event.

Permeability Modeling Considering Microstructure of Preform

2007 ◽  
Vol 334-335 ◽  
pp. 437-440 ◽  
Author(s):  
Do Hoon Lee ◽  
Joon Ho Lee ◽  
Woo I. Lee
Keyword(s):  
Porous Medium ◽  
Unsaturated Flow ◽  
Manufacturing Industries ◽  
Experimental Measurements ◽  
Resin Flow ◽  
Flow Conditions ◽  
Composite Manufacturing ◽  
Liquid Molding ◽  
Flow Through ◽  
Inhomogeneous Microstructure

Liquid molding processes are becoming more popular among the composite manufacturing industries due to their versatility and economy among other merits. In analyzing the flow during the process, permeability is the most important parameter. Permeability has been regarded as a property of the porous medium. However, in many practical cases, the value may vary depending on the flow conditions such as the flow rate. It is speculated that this deviation is caused by inhomogeneous microstructure of the medium. In this study, numerical simulations as well as experimental measurements have been done to investigate the cause of deviation. Microstructure of porous medium was modeled as an array of porous cylinders. Resin flow through the array was simulated numerically. Simulations were performed for two different flow conditions, namely saturated flow and unsaturated flow. Based upon the results, permeabilities were estimated and compared for the two flow conditions. In addition, a model was proposed to predict the permeability for different flow conditions. Results showed that experimental data were in agreement with the prediction by the model.

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