Northern Sichuan lies in an area with high tectonic activity. In this region, the Tibetan Plateau abuts against the Yangtze Plate with immense pressure forming faults along the edges. Jiuzhaigou County is located in the Min Mountains, a range that was formed at the intersection of these faults. The devastating 1879 Gansu earthquake had its epicenter approximately to the east of where the 2017 Jiuzhaigou earthquake occurred. The mountainous areas to the south of Jiuzhaigou County were the epicenter of the 2008 Sichuan earthquake that resulted in tens of thousands of fatalities. The Jiuzhaigou earthquake did not correlate with any of the known active faults. Field investigation and remote sensing of the surface effects of the earthquake permitted the identification of a previously-unknown active fault segment.
Impacts
According to what the China Earthquake Administration announced, the graph showed that the seismic intensity could be higher than level IX, and the earthquake epicentre in Zhangzha County could reach level VIII. The earthquake triggered at least 1,883 landslides, most of which were shallow rock slides, debris slides and rock falls that occurred close to the road network. After the earthquake, the entire Jiuzhaigou County completely suffered a power failure. The eyewitnesses found that some buildings had fallen off in Jiuzhaigou Valley Scenic and Historic Interest Area. The staff of the Jiuzhaigou Valley Scenic and Historic Interest Area told the correspondent from Xinhua News Agency that in the fourth ditch of the Jiuzhaigou Valley Scenic and Historic Interest Area a house had collapsed and cracked, and the locals were stepping up to evacuate people.
Rescue
The China Earthquake Administration put up a Level I reaction, changing to Level II afterwards, and sent troops to the earthquake area for rescue. At 21:26 CST, started an emergency plan, and the medical rescue team was going to head to the earthquake area within one hour. The Red Cross Society of China, Sichuan Branch was on emergency standby, preparing for rescue. In the small hours the next day, China's State Council Earthquake relief headquarters established national level Ⅱ earthquake emergency response. At 06:20 CST on 9 August, a Shuajingsi Town militia vehicle had a traffic collision to a Sichuan F coach in Hongyuan County, Ngawa Prefecture. 3 people from the coach were injured and were being medically treated. Until 9 August 2017, there were 40 people critically injured, 7 of whom were transferred to other hospitals, 4 to West China Hospital of Sichuan University, and the rest to Jiuzhaigou County Hospital and Zhongzang Hospital.
Casualties
The Emergency Management Office of the Ngawa Prefecture, Sichuan Province announced that until 13:10 CST on 9 August, the 7.0-magnitude earthquake in Zhangzha Town in Jiuzhaigou County killed 19 people and injured 247 people, including 40 people critically injured. The following day, the death toll rose to 20 with over 400 injured. Deaths and injuries mainly occurred in Zhangzha Town in Jiuzhaigou County.
Aftershocks
As of 10 August 2017 10:00 CST, 1,741 aftershocks had occurred, including 30 major ones. Some experts predicted that the aftershocks might reach a magnitude of 6 after several days. The major aftershocks reported by China Earthquake Networks Center are listed below:
