With all the information given it is hard to find the magnitude. It looks like the secondary chart says 7.5.
From USGS:
M 7.5 - 37km N of Tecpan de Galeana, Mexico
Time: 2014-04-18 10:27:29 UTC-04:00
Location: 17.585°N 100.741°W
Depth: 48.6km
Has anyone heard anything about tsunami warnings, since this was a coastal area?