The United States Geological Survey Recorded a Magnitude 5.4 Earthquake at a depth of 79.4 km about 15 km to the east of the municipality of La Gomera in Esculinta Department in southern Guatemala, slightly before 5.35 am local time (slightly 11.35 am GMT) on Friday 16 December 2016. This event was felt across much of central and southern Guatemala, as well as parts of El Salvador, though there are no reports of any damage or casualties; which is roughly what would be expected from an Earthquake of this size at this depth; the quake is big enough to be felt over a wide area, but most of its energy has dissipated before the shock-waves reach the surface.
The approximate location of the 16 December 2016 Guatemala Earthquake. USGS.
Guatemala is located on the southern part of the Caribbean Plate, close to its boundary with the Cocos Plate, which underlies part of the east Pacific. The Cocos Plate is being pushed northwards by expansion of the crust along the East Pacific Rise, and is subducted beneath the Caribbean Plate along the Middle American Trench, which runs parallel to the south coast of Guatemala and neighbouring countries, passing under Central America as it sinks into the Earth's interior. This is not a smooth process, the plates tend to stick together, breaking apart again once the pressure from the northward movement of the Cocos Plate builds up to much, triggering Earthquakes.
Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. The international non-profit organisation Earthquake Report is interested in hearing from people who may have felt this event; if you felt this quake then you can report it to Earthquake Report here.