  Twitter is a popular public conversation platform with world-wide audience
and diverse forms of connections between users. In this paper we introduce the
concept of aggregated regional Twitter networks in order to characterize
communication between geopolitical regions. We present the study of a follower
and a mention graph created from an extensive data set collected during the
second half of the year of $2012$. With a k-shell decomposition the global
core-periphery structure is revealed and by means of a modified Regional-SIR
model we also consider basic information spreading properties.
