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Table 1 Contingency table of evaluated foreshock probabilities and actual portion of foreshocks with 90% binomial proportion confidence interval in seismic clusters of size N = 2, 5, 10, 20

From: Cluster-based foreshock discrimination model with flexible time horizon and mainshock magnitudes

Foreshock probability

0–10%

10–20%

20–30%

30–40%

40–50%

50–60%

60–70%

70–80%

Total

N = 2

All clusters

469

489

220

59

14

2

0

0

1253

Foreshock clusters

27

67

45

17

4

2

0

0

162

Portion of foreshocks (90% CI)

6% (4–8%)

14% (11–17%)

20% (16–25%)

29% (19–40%)

29% (10–54%)

100% (22–100%)

N/A

N/A

13%

N = 5

All clusters

129

57

27

13

9

3

2

2

242

Foreshock clusters

8

12

4

3

3

1

1

2

34

Portion of foreshocks (90% CI)

6% (3–11%)

21% (13–32%)

15% (4–34%)

23% (7–49%)

33% (10–66%)

33% (2–86%)

50% (3–97%)

100% (22–100%)

14%

N = 10

All clusters

68

7

3

5

4

2

2

0

91

Foreshock clusters

5

3

1

2

3

1

0

0

15

Portion of foreshocks (90% CI)

7% (3–15%)

43% (13–77%)

33% (2–86%)

40% (8–81%)

75% (25–99%)

50% (3–97%)

0% (0–78%)

N/A

16%

N = 20

All clusters

34

1

2

1

0

2

0

3

43

Foreshock clusters

1

1

1

1

0

1

0

1

6

Portion of foreshocks (90% CI)

3% (0–13%)

100% (5–100%)

50% (3–97%)

100% (5–100%)

N/A

50% (3–97%)

N/A

33% (2–86%)

14%