At 4.35 am on 4 December 2016, which happened to coincide with a full moon, a magnitude 6.7 earthquake struck about 30 kilometres west of Mercator de Terremotia, at a relatively shallow depth. The quake was caused by movement along a previously unrecognised minor fault line that had not been mapped. The fault line lies deep under alluvial soils laid down by a river coming out of a large mountain chain. The earthquake caused significant building damage to the city, especially to old masonry buildings, but no direct fatalities. In the subsequent months, many smaller aftershocks (generally < magnitude 4) followed. 3 Despite Terremotia’s long history of earthquakes, good science and monitoring systems, the “Mercator earthquake” and its aftershocks caught everyone by surprise because the city had not been considered to be at high risk. The surprise opened the space for speculation, in which astrologers, psychics and other “alternative forecasters” moved in. Using social media platforms, such as YouTube channels and Facebook pages, these forecasters attracted dedicated followers. Some of them claimed that the earthquake was due to the full moon and predicted another and much larger earthquake in or near Mercator, would happen one day when other astrological features would be aligned to cause a “greater pull”.