State news agency Antara reported Monday the 5.1 earthquake shook Sipura Mentawai at 2 a.m. The earthquake's epicenter was 55 kilometers northwest of Sipura Mentawai at a depth of 10 kilometers below sea level.

At 1 a.m, an unrelated 5.3 quake hit Manokwari, a possible aftershock to the 7.3- and 7.6-amplitude quakes that rocked that regency Jan. 4. The epicentre was 151 kilometers southwest of the regency, 10 kilometers below the sea level. Neither quake caused a tsunami. (ewd)