Visualization of italian earthquakes data.
I get the data from
Rovida A., Locati M., Camassi R., Lolli B., Gasperini P. (eds), 2016. CPTI15, the 2015 version of the Parametric Catalogue of Italian Earthquakes. Istituto Nazionale di Geofisica e Vulcanologia. doi:http://doi.org/10.6092/INGV.IT-CPTI15
Then I select the earthquakes where the time is known to the seconds and I plot the Default Moment Magnitude (MwDef) of said earthquakes versus the time of day, this is the plot I get:
The oldest earthquake in this selection happened in 1801 (1801-10-08 07:52:53 with epicentre in the Bolognese area and with MwDef=4.9) and the 1957 events are about the 42% of the entire dataset.
In order to get more events I select the earthquakes where the time is known to the hours and I get a subset of 3818 events that now are about the 83% of the entire dataset. The oldest earthquake happened in 1044-04-19 09:00:00 with epicentre in the city of Benevento and with MwDef=4.63.
This graph shows a vertical stripe pattern due to the fact that now the time of the earthquakes is known only to the hour.
I sorted the events known to seconds in this file with descending MwDef (stronger first) and the 80% of the top ten eartquakes happened at night.
I do the same for the events known to hours in this file and in that case the 50% of the top ten eartquakes happened at night.
The code to discriminate day from night is is.night by Luke A. Winslow in library LakeMetabolizer.
Some info about the forecasts of earthquakes (in Italian): Cosa sta facendo e cosa ha fatto l'INGV nel campo della previsione dei terremoti?.