  Social media platforms have been extensively used during natural disasters.
However, most prior work has lacked focus on studying their usage during
disasters in the Global South, where Internet access and social media
utilization differs from developing countries. In this paper, we study how
social media was used in the aftermath of the 7.1-magnitude earthquake that hit
Mexico on September 19 of 2017 (known as the #19S earthquake). We conduct an
analysis of how participants utilized social media platforms in the #19S
aftermath. Our research extends investigations of crisis informatics by: 1)
examining how participants used different social media platforms in the
aftermath of a natural disaster in a Global South country; 2) uncovering how
individuals developed their own processes to verify news reports using an
on-the-ground citizen approach; 3) revealing how people developed their own
mechanisms to deal with outdated information. For this, we surveyed 356 people.
Additionally, we analyze one month of activity from: Facebook (12,606 posts),
Twitter (2,909,109 tweets), Slack (28,782 messages), and GitHub (2,602
commits). This work offers a multi-platform view on user behavior to coordinate
relief efforts, reduce the spread of misinformation and deal with obsolete
information which seems to have been essential to help in the coordination and
efficiency of relief efforts. Finally, based on our findings, we make
recommendations for technology design to improve the effectiveness of social
media use during crisis response efforts and mitigate the spread of
misinformation across social media platforms.
