Table 3 Contingency table of evaluated foreshock probabilities for M6+ mainshocks 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 | 0–5% | 5–10% | 10–15% | 15–20% | 20%– | Total | |
|---|---|---|---|---|---|---|---|
N = 2 | All clusters | 1234 | 17 | 2 | 0 | 0 | 1253 |
Foreshock clusters | 28 | 0 | 1 | 0 | 0 | 29 | |
Portion of foreshocks (90% CI) | 2% (2–3%) | 0% (0–16%) | 50% (3–97%) | N/A | N/A | 2% | |
N = 5 | All clusters | 212 | 24 | 5 | 1 | 0 | 242 |
Foreshock clusters | 12 | 4 | 0 | 0 | 0 | 16 | |
Portion of foreshocks (90% CI) | 6% (3–9%) | 17% (6–34%) | 0% (0–45%) | 0% (0–95%) | N/A | 7% | |
N = 10 | All clusters | 84 | 4 | 2 | 1 | 0 | 91 |
Foreshock clusters | 8 | 1 | 1 | 1 | 0 | 11 | |
Portion of foreshocks (90% CI) | 10% (5–17%) | 25% (1–75%) | 50% (3–97%) | 100% (5–100%) | N/A | 12% | |
N = 20 | All clusters | 36 | 4 | 0 | 1 | 2 | 43 |
Foreshock clusters | 2 | 1 | 0 | 1 | 1 | 5 | |
Portion of foreshocks (90% CI) | 6% (1–16%) | 25% (1–75%) | N/A | 100% (5–100%) | 50% (3–97%) | 12% | |