After the first analysis of what happened on Twitter during the first 24 h after the earthquake that on May 20th struck the northern part of Italy, we can now go a little deeper in our description by focusing on two specific time-frames. According to what we’ve pointed out in the previous article there were two major peaks of Twitter activity corresponding to the two major seismic episodes recorded that day: one was approximately at 4 am while the second was approximately at 3 pm. Since we have described in these two episodes a rather different Twitter activity in terms of ratio between original tweets and reTweets we have decided to observe these two windows of 2 hours each with a higher level of details (Figure 1 and Figure 2).
When Tweet are observed on a 1 minute time scale we can see a rather different scenario. In every case when the earthquake arrived (two events in Figure 1 and 1 event in Figure 2) we have a peak in original tweet production mainly made by people witnessing the earth shaking and twitting about it. Soon after that the propagation process mainly made of retweets takes back its prominence. The lapse of time between the information phase (when original Tweets outnumber the ReTweets) and the propagation phase (when ReTweets outnumber the original Tweets) can be explained by many elements but it seems likely to be related to the number of active users and to the level of novelty of the information.
According to this analysis we can say that – observing the phenomenon on a 1 minute time frame – the sequence information/propagation seems to be confirmed on both moments. Nevertheless it is possible to point out some differences between these two moments according to the content of the tweets and, therefore, to their social function. We are going into that aspects in part 3 that will be published in few days.