The tremor occurred at 5:23 a.m. local time about 30 miles (50 km) beneath rough terrain near the Pacific coast.
The epicenter was placed just north of the town of Crucecita, according to government seismologists.
"Yes, it woke up some people, but others didn't feel it. We monitored the entire state, above all the coast and the Isthmus (of Tehuantepec)" and no damage was reported, Oaxaca's Civil Protection director, Martin Vela Gil, told the EFE news agency.
