This exploratory observational study analyzes the variation of the total amount of vertical electrons (vTEC) in the ionosphere, 17 days before telluric events with grades greater than M7.0 between 2015 and 2016. Thirty telluric events have been analyzed with these characteristics. The data was obtained from 55 satellites and 300 GPS receivers that were downloaded from the Center for Orbit Determination in Europe (CODE). The variations are considered significant only if it is outside the "normal" ranges considered after the statistical analysis performed. The data was downloaded by a program developed in our laboratory. The downloaded data was processed and maps of variations of vTEC generated with a periodicity of 2 hours. The analysis area was considered to be a circular one with a radius of 1000km centered on the epicenter of each earthquake. Variation of vTEC was found during 2015-2016 in 100% of the earthquakes in the range from day 1 to day 17 days before the event, over the circular area of 1000 km radius centered on the epicenter of the earthquake. Of these in 96.55% there are positive variations and a negative one exist in 68.97% of the events. If we observe in the range from day 3 to 17 before the event, a variation was recorded in 100% of the cases, and from day 8 to day 17 before the event in 93.10% of the cases, it is important to emphasize that while the evidence in a period before the event is more likely to find evidence to develop early warning tool for earthquake prevention. This study explores the variation of vTEC as precursor events to each earthquake during 2015-2016; it is a preliminary analysis that shows us the feasibility of analyzing this information as a preamble for an exhaustive association study later. The final objective is to calculate the risk of telluric events which would benefit the population worldwide.