Table 1. Landslide densities, mean recurrence intervals, and probability (percent chance) of one or more landslides occurring during a specified time in the future. Exceedance probabilities of 100 percent have been rounded up from values that were greater than 99.995.

Density (number of landslides per 4 hectare count circle)

Mean Recurrence Interval (years)

Exceedance Probability (percent chance of one or more landslides during a specified time)

1 yr.

5 yrs.

10 yrs.

25 yrs.

50 yrs.

100 yrs.

1

88.40

1.12

5.50

10.70

24.63

43.20

67.74

2

44.20

2.24

10.70

20.25

43.20

67.74

89.59

3

29.47

3.34

15.61

28.78

57.19

81.67

96.64

4

22.10

4.42

20.25

36.40

67.74

89.59

98.92

5

17.68

5.50

24.63

43.20

75.68

94.09

99.65

6

14.73

6.56

28.78

49.27

81.67

96.64

99.89

7

12.63

7.61

32.69

54.70

86.19

98.09

99.96

8

11.05

8.65

36.40

59.54

89.59

98.92

99.99

9

9.82

9.68

39.89

63.87

92.15

99.38

100

10

8.84

10.70

43.20

67.74

94.09

99.65

100

11

8.04

11.70

46.32

71.19

95.54

99.80

100

12

7.37

12.69

49.27

74.27

96.64

99.89

100

13

6.80

13.68

52.06

77.02

97.47

99.94

100

14

6.31

14.65

54.70

79.48

98.09

99.96

100

15

5.89

15.61

57.19

81.67

98.56

99.98

100

16

5.53

16.56

59.54

83.63

98.92

99.99

100

17

5.20

17.49

61.77

85.38

99.18

99.99

100

18

4.91

18.42

63.87

86.95

99.38

100

100

19

4.65

19.34

65.86

88.34

99.54

100

100

20

4.42

20.25

67.74

89.59

99.65

100

100

21

4.21

21.14

69.51

90.70

99.74

100

100

22

4.02

22.03

71.19

91.70

99.80

100

100

23

3.84

22.91

72.77

92.59

99.85

100

100

24

3.68

23.78

74.27

93.38

99.89

100

100

25

3.54

24.63

75.68

94.09

99.91

100

100

26

3.40

25.48

77.02

94.72

99.94

100

100

 

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