The emergency response period runs from Aug. 15 to Aug. 28, said the decree issued by Melki Laka Lena, governor of East Nusa Tenggara province.
The earthquake was centered about 30 km northeast of Mbay in Nagekeo Regency at a depth of 15 km, according to the decree, Xinhua reported.
Indonesia's National Disaster Management Agency said the earthquake and 341 aftershocks had left 51 people dead and 113 others injured.
A total of 3,356 people were taking refuge in Sikka, 2,078 in Manggarai and 500 in Nagekeo, while others were displaced in Bima and Selayar.
The quake damaged 914 houses heavily, 126 moderately and 317 lightly. It also damaged 93 educational facilities, 36 health facilities and 38 government offices.
The provincial government said the emergency response status was aimed at facilitating disaster response, evacuation, relief distribution and recovery efforts in affected areas.