Resilience can be interpreted as the comprehensive ability of a system to prepare for, absorb, and recover from external or internal disturbances and shocks. In the context of human mobility, resilience therefore refers to the ability of people's movements within and between cities to cope with and adapt to disruptive events, such as natural disasters. On July 20, 2021, a record-breaking heavy rainfall occurred in the Zhengzhou region, Henan province, China, an inland densely-populated region with a total area of 7600 km2, 12.7 million residents, and a 79.1% urbanization rate. The region is located in a semiarid area and is known for its relatively low average annual precipitation. This unexpected heavy rainfall led to an extreme urban flood, causing massive injuries to the public and losses in critical infrastructure systems, with a death toll of 380; nearly two million people were affected. Very quickly, this apocalyptic event in central China drew extensive attention globally. Using 1.32 billion mobile phone signaling records generated by 4.35 million people during the "720" Zhengzhou flood event, researchers from Peking University, Henan University, and Key National Geomatics Center of China jointly analyzed how people's mobility responded to this extreme urban flood disaster during the 2021 summer.
