I am pretty sure that these lunar phases are periods of heightened activity for some volcanoes:
18 Apr 12:31
25 Apr 19:57
2 May 11:14
10 May 00:29
18 May 04:35
25 May 04:25 …
The first part of each line is the date of the phase and the second is the time that the astronomical exactitude takes place. The moon is only exactly on the quarter for a few seconds -if that. This is because the earth, moon and sun only make an angle that is divisible by 90 for the merest moment.
There appears to be no reason for the significance of this mathematical idea, except that the timing locates the region on the earth over which the phenomenon takes place. There is no reason for anyone to take and interest in these facts and so few do.
The position of the sun, earth and moon is not really of much use to anyone, navigators or astronomers. Or anyone else as far as I know. It can't be used to project calendars as the difficulty in predicting the position of the moon had, for milennia, made the idea preposterous. It has only fairly recently been possible to predict the positions of the moon with accuracy.
We know the length of the lunar month is roughly 29 ½ days but a calendar based on that approximation would soon go to hell. The speed of the earth around the sun varies with the season and the speed of rotation of the moon about the earth varies with the lunar season.
The nearness of the moon to the earth affects its speed around the earth and this varies every 27.3 days.
So the position of the moon in the sky is already a complex mathematical formula. Not all that complex but not straight forward. Getting its position truly accurately is something that is still not possible at the moment. The tables can be drawn up years in advance because we know roughly where the moon is going to be. But a few months before the tables are printed, there is a final recalibration.
A navigator's alamanack is prepared 12 months in advance with final adjustments included in a separate loose page added to the final printing at the last moment. This is because correction are still being made at the last moment.
Not that many navigators still use lunar tables for navigation.
Astronomers still use their versions of such tables. But they are not a matter of life and death in such exhalted circles.