New/Full Moon influence

[Karma: 37 pts]

HookEcho

April 27, 2017 at 3:22 pm #1453

While not a new topic, still relevant and should have a home here at quakewatch: In a study just published in Nature Geoscience, University of Tokyo researchers report that of the 12 largest recorded earthquakes — those with a magnitude of 8.2 or more — over the past two decades, nine occurred on days near new or full moons, when the gravitational tidal pull caused high stress across the fault. Earthquake potential revealed by tidal influence on earthquake size–frequency statistics http://www.nature.com/ngeo/journal/v9/n11/full/ngeo2796.html

Score: 0

[Karma: 37 pts]

HookEcho

April 28, 2017 at 3:43 am #1455

Short term study we did focusing on the relationship between lunations and the rate of earthquakes greater than 6.0.
What this study does is analyze whether earthquakes increase during the five days before a lunation, or if there is no effect. There are 203 periods of 5 days each where for each 5 day period the sum of the number of quakes that occurred during that period were compared with an increase in quakes as proposed during these periods. The New moons did indicate that there was a correlation between the number of earthquakes and the period prior to a new moon.
this correlation was significant at the 95% confidence level.

Conclusion:
Earthquakes generally tend to increase as the new moon approaches, but the full moons have no significant effect.
[Graphs linked below]

Statistics:
For New Moons:
R Score:
N:

Significance Level:
0.01
0.05
0.10
The P-Value is 0.047303. The result is significant at p < 0.05.

X Values
∑ = 390
Mean = 1.921
∑(X – Mx)2 = SSx = 624.739

Y Values
∑ = 140
Mean = 0.69
∑(Y – My)2 = SSy = 463.448

X and Y Combined
N = 203
∑(X – Mx)(Y – My) = 75.034

R Calculation
r = ∑((X – My)(Y – Mx)) / √((SSx)(SSy))

r = 75.034 / √((624.739)(463.448)) = 0.1394

Meta Numerics (cross-check)
r = 0.1394 Key

X: X Values
Y: Y Values
Mx: Mean of X Values
My: Mean of Y Values
X – Mx & Y – My: Deviation scores
(X – Mx)2 & (Y – My)2: Deviation Squared
(X – Mx)(Y – My): Product of Deviation Scores

For Full Moons:
Result Details & Calculation

X Values
∑ = 390
Mean = 1.921
∑(X – Mx)2 = SSx = 624.739

Y Values
∑ = 136
Mean = 0.67
∑(Y – My)2 = SSy = 452.887

X and Y Combined
N = 203
∑(X – Mx)(Y – My) = 14.719

R Calculation
r = ∑((X – My)(Y – Mx)) / √((SSx)(SSy))

r = 14.719 / √((624.739)(452.887)) = 0.0277

Meta Numerics (cross-check)
r = 0.0277 Key

R Score:
N:
Significance Level:
0.01
0.05
0.10
The P-Value is 0.694835. The result is not significant at p < 0.10.

For both New moons and full moons as peaks:
R Score:
N:
Significance Level:
0.01
0.05
0.10
The P-Value is 0.194167. The result is not significant at p < 0.10.

New Moon as Peaks and Full Moons as detractors:

R Score:
N:
Significance Level:
0.01
0.05
0.10
The P-Value is 0.173043. The result is not significant at p < 0.10.

Full moon/earthquakes:
https://drive.google.com/file/d/0B83EkoitOiKQd3dDY2pRNHVjVDA/view?usp=sharing

New moon/earthquakes:
https://drive.google.com/file/d/0B83EkoitOiKQYjJoZ3hObW1vbUU/view?usp=sharing

Score: 0