People across the island — the smallest in the Canary chain — felt the earthquake just before 6am this morning, reported Te Interesa.
The epicentre of the quake was 16km under the sea east of the town of Frontera.
This was the strongest earthquake recorded on the island since El Hierro started experiencing seismic activity again on March 15th.
Spain's National Geographic Institute said El Hierro had experienced 56 earthquakes since midnight on Sunday, with 17 of these measuring above 3.0 on the Richter Scale.
Last weekend, the island clocked up 329 individual earthquakes.
According to the website Earthquake Report, seismic activity on the island has slowed today after a busy night.
El Hierro experienced intense earthquake experience in 2011 and 2012 as part of volcanic activity just off the island's coast.
Submarine volcanic eruptions from October 2011 to March 2012 saw residents of La Restinga evacuated twice and dead fish were found in ocean waters.