| Fig. 1 |
View of Debris avalanche of Mt. St. Helens
at 8:32 AM on 18 May 1980. |
| Fig. 2 |
Structure of debris-avalanche deposit of Mt. St.
Helens. |
| Fig. 3 |
Overview of the experimental apparatus. |
| Fig. 4 |
Track A near the catapult. |
| Fig. 5 |
Track B in midway of the whole of
track. |
| Fig. 6 |
Track C at the end of the track. |
| Fig. 7 |
Example of the disk velocity on the flour layer
versus time elapsed from shooting. |
| Fig. 8 |
Example of the disk velocity without the flour
layer versus time elapsed from shooting. |
| Fig. 9 |
Range in which friction coefficient was obtained. |
| Fig. 10 |
Friction coefficient versus basal pressure of disk. |
| Fig. 11 |
Speed at which the state of sliding change from
Phase B to C. |
| Fig. 12 |
Speed at which the state of sliding change from
Phase B to C versus basal pressure of disk. |
| Fig. 13 |
Preparation of the cross section. Line a, b and
c show the position of the cross section of Fig. 14. |
| Fig. 14 |
Cross sections of the powder layer. |
| Fig. 15 |
Distance between the top of the disk and a
surface of the track board. |
| Fig. 16 |
Friction coefficient versus basal pressure of
disk. |
| Fig. 17 |
Friction coefficient versus basal pressure of
disk. |
| Fig. 18 |
Velocity of the disk versus time elapsed since disk was
shot. |
| Fig. 19 |
Friction coefficient versus basal
pressure of disk. |
| Fig. 20 |
Friction coefficient versus basal
pressure of disk. |
| Fig. 21 |
Friction coefficient versus basal
pressure of disk. |
| Fig. 22 |
Schema of a floating critical
speed. |
| Fig. 23 |
Schema of Newtonian lifting
force model. |
| Fig. 24 |
Schema of dynamic pressure
model. |
| Fig. 25 |
Theoretical and experimental values
of the floating critical speed. |
| Appendix Fig. 1 |
A magnified image of flour used in
experiments. |
| Appendix Fig. 2 |
A magnified image of violet dogtooth
starch used in experiments. |
| Appendix Fig. 3 |
A magnified image of silica sand used
in experiments. |
| Appendix Fig. 4 |
The base part of the disk. Four base
parts were made. |
| Appendix Fig. 5 |
The catapult. |
| Appendix Fig. 6 |
The sieve machine. |
| Appendix Fig. 7 |
The track board. |
| Appendix
Fig. 8 |
The laser displacement sensor. |
|
|
| Tables |
| Table
1 |
List of experiment condition. |
| Table
2 |
List of experiment condition and
friction coefficient. |
| Appendix
Table 1 |
Relation between the basal state of the
disk and clinging of powder. |
| Appendix
Table 2 |
List of disks 140 mm in diameter. |
| Appendix
Table 3 |
List of disks 100 mm in diameter. |
|
|
| Movies |
