The heights of these blocks determined as a result of field studies varied from 0.8-2/23 m, with lengths from 0.96–3.2 m and widths of 1.16–2.5 m (Fig. 6). According to models obtained by defining these measured dimensions in the RAMMS program, the volumes of the blocks varied from 7.96 m3- 0.46 m3, while masses varied from 214,485 kg-1253 kg. According to the measured values, the block shapes were identified as equant, real long, real equant and real flat. According to these features defined in the RAMMS program, 100 repeats for each of the 17 blocks were modelled for a total of 1700 blocks. As a result of this modelling, the kinetic energy (kJ), velocity (m/s), jump height (m) and rockfall hazard index features were determined for each block.
Rocks display variations in the distance covered after falls linked to the shape and volume of the block, in addition to being shaped by the features of the slope. As understood from the values obtained accordingly, on vertical and high-slope areas where slope values are high but discontinuous, blocks stop before being transported a very advanced distance. This situation is clearly observed for blocks R2, R3, R5 and R6 and the slope values for these rocks are generally above 46°, equivalent to vertical slopes and high cliffs. For rocks in areas where the slope values are continuous, blocks appear to be transported over very long distances. As seen for blocks R1, R4, R6, R7, R8, R9, R10, R11, R12, R14, R15, R16, and R17, variable rounding features are present according to the geometry of the blocks. Apart from this, R12 block has a continuous slope profile; however, the block could not progress a long distance due to the different shape (real long).
There is a parallel between the kinetic energy released and the volume and geometry of the block and the continuity of slope values. Fall properties of blocks R2, R3, R4, R5 and R6 had mean 479 kJ kinetic energy, rising to a maximum of 1183 kJ. Other rocks with more rounded features (R1-R6-R7-R8-R9-R10-R11-R12) had mean 726 kJ kinetic energy reaching a maximum of 3476 kJ (Fig. 7).
While the geometric properties of the rocks play an important role in their progression, the geomorphology of the field in which the rockfall event occurs is also effective. Generally, the trajectories of blocks are shown on red relief images in order to better understand the slope features and general topographic characteristics of the study area in general. Accordingly, the modelling for R2, R3, R4, R5 and R6 appear to show they are channelled into valleys and do not reach the settlement area and model results generally end in the middle of the valley. Apart from these, it appears that modelling of blocks with lower slope rates and without narrow or deep values in geomorphological terms affect settlement areas more and leave them at risk (Fig. 7).
Just as the geometric shapes of rocks and slope features of the area affect the kinetic energy, they directly affect the rock velocity and the bounce height. Generally, high velocities and jump heights are equivalent to areas where kinetic energy reaches maximum levels. As a result of modelling for 17 different rock blocks, maximum velocities were 8.1–23.1 m/s. Maximum bounce heights varied from 1.9 m to 14.5 m (Table 1). The block with lowest value appeared to be block number R4 with real flat geometry (Table 2).
4.1. Rockfall Hazard Assessment
The trajectories and values emerging as a result of block modelling involve great hazards for settlement units. Rockfalls from vertical and close-to-vertical steep slopes generally stop on roads and there is no contact with settlement units. However, apart from blocks number R2, R3 and R5, it appears that damage to residential units is unavoidable in modelling of the rockfall of 14 different blocks. Apart from these, blocks with rounded features cause some completely different outcomes to emerge. These rocks have very high-risk status due to being transported over long distances. It appears they may cause great damage and even loss of life due to high energy, velocity and bounce features. The hazard status emerging as a result of modelling of blocks identified based on field studies in the study area are included in Table 2.
Table 2
Results for blocks with fall hazard (H: House, T: Tree, R: Road)
No
|
Max. kinetic energy (kJ)
|
Max. velocity (m/s)
|
Max. jump height (m)
|
Max. distance travelled
(m)
|
Element at risk
|
R1
|
3476.8
|
16.73
|
5.25
|
127.5
|
H,T,R
|
R2
|
1183.5
|
14.53
|
4.25
|
85
|
T,R
|
R3
|
160.6
|
10.15
|
2.27
|
97
|
H,T,R
|
R4
|
383.1
|
16.46
|
5.75
|
112
|
H,T,R
|
R5
|
90.6
|
8.17
|
1.99
|
75
|
|
R6
|
581
|
17.9
|
9.02
|
87
|
H,T
|
R7
|
131
|
17.19
|
8.71
|
55
|
Abandoned H
|
R8
|
397.5
|
19.93
|
7.83
|
120
|
H,T,R
|
R9
|
185.2
|
16.51
|
6.84
|
85
|
H,T,R
|
R10
|
285.4
|
13.71
|
6.05
|
84
|
H,T,R
|
R11
|
701
|
23.1
|
14.57
|
87
|
H,T,R
|
R12
|
166
|
12.06
|
4.1
|
56
|
H,T
|
R13
|
630
|
8.74
|
4.55
|
34
|
H
|
R14
|
441
|
13
|
6.23
|
45
|
H
|
R15
|
312
|
14.63
|
6.42
|
67
|
H,T,R
|
R16
|
257.4
|
10.61
|
3.04
|
53
|
H,T
|
R17
|
1737.6
|
16.05
|
10.1
|
70
|
H,T,R
|
According to the hazard map, modelling of rocks R6, R12, R13, R14, R15, R16 and R17 show the majority of high and moderate risk areas are settlement areas. Modelling of blocks R1, R4, R7, R8, R9 and R10 show the majority involve low hazard, while a small portion involve moderate degree of hazard (Fig. 8).