No major collapses or extensive damage to buildings has occurred in Zhangzha, the town at the epicenter of the 7.0-magnitude earthquake that hit southwest China's Sichuan Province Tuesday.

The powerful quake struck Jiuzhaigou County at 9:19 p.m. Tuesday. Twenty people have been confirmed dead while 431 reported injuries, including 18 seriously injured, as of noon Thursday.

Zhangzha's buildings appear to have stood up well to the strong tremors, according to satellite and aerial images.

The Institute of Remote Sensing and Digital Earth (RADI) under the Chinese Academy of Sciences reported its findings after comparing remote sensing satellite images of Zhangzha and surrounding areas before and after the earthquake.

The institute said its ground stations began collecting data from China's Gaofen-4 and Gaofen-2 satellites early Wednesday.

The two satellites are part of China's seven-satellite indigenous Earth observation program to be completed by 2020.

Aerial images taken by a military surveillance plane and civilian drones showed similar findings. Clusters of residential buildings, bridges and roads in Zhangzha seemed to have escaped the quake unscathed.

The town is nestled in a valley surrounded by towering tree-covered mountains.

Situated on a plateau 2,000 meters above sea level, Jiuzhaigou County covers 5,290 square kilometers and has about 81,000 residents, according to a survey in 2015.

The county includes a UNESCO natural heritage site and national park known for plateau lakes, stunning waterfalls and scenic mountains.

Tourist sites have suffered severe damage as landslides pushed mud and rocks into the lakes, according to Xinhua photographers who were allowed into the national park Thursday. Some once pristine lakes now have murky water, while others have been drained of water due to cracks in the surrounding mountains.

Researchers from RADI said satellite images showed multiple landslides within in the park and they believe more could occur.

Meanwhile, rescue workers are spreading out to reach every corner of the quake zone. So far, they have evacuated than 50,000 tourists, including 126 foreigners, and over 9,000 local residents.

Power supply has been restored to many areas, most road blocks have cleared, while restaurants and convenience stores reopened in Jiuzhaigou Township, the county seat, Thursday.