Table 3. F-test results for linear regression models applied to gravity changes before eruptions and impulsive tilt events in February and March 2011. T#3 and T#17 are not tested due to the limited number of data with suitably small errors.
Event ID in Fig. 2 | Date and time (UT) | Number of data N | Gravity change rate (μgal/hour) | F(1, N − 2) | Critical F for 1% confidence (5%) |
|---|---|---|---|---|---|
T#1 | 11:00–13:00, Feb. 11 | 5 | −1.04 | 86.8 | 34.1 |
VE#1 | 02:36, Feb. 11 | 5 | −0.83 | 95.0 | 34.1 |
T#2 | 05:00, Feb. 13 | 5 | −1.80 | 42.4 | 34.1 |
VE#2 | 20:07, Feb. 13 | 11 | −0.96 | 50.4 | 10.6 |
T#3 | 05:00, Feb. 15 | – | – | – | – |
T#4 | 19:00, Feb. 15 | 7 | −1.40 | 24.8 | 16.3 |
T#5 | 09:00, Feb. 16 | 10 | −1.05 | 35.4 | 11.3 |
VE#3 | 09:16, Feb. 18 | 9 | −1.66 | 16.7 | 12.2 |
T#6 | 18:30, Feb. 19 | 6 | −1.35 | 10.5 | 21.2 (7.7) |
T#7 | 08:25, Feb. 20 | 10 | −1.24 | 15.0 | 11.3 |
T#8 | 07:45, Feb. 22 | 10 | −2.14 | 39.2 | 11.3 |
T#9(E) | 15:00–16:00, Feb. 22 | 9 | −1.40 | 24.5 | 12.2 |
T#10 | 10:50, Feb. 23 | 13 | −0.68 | 15.5 | 9.6 |
T#11 | 14:00–18:37, Feb. 23 | 10 | −0.52 | 5.4 | 11.3 (5.3) |
E#4 | 08:00, Feb. 28 | 9 | −1.47 | 22.1 | 12.2 |
T#16 | 12:00, Feb. 28 | 7 | −2.25 | 39.2 | 16.3 |
T#17 | 20:30, Mar. 25 | – | – | – | – |
T#18 | 09:30, Mar. 26 | 11 | −1.21 | 21.1 | 10.6 |
T#19 | 04:30, Mar. 28 | 14 | −0.85 | 20.1 | 9.3 |
E#5 | 18:33, Mar. 28 | 10 | −0.71 | 10.9 | 11.3 (5.3) |