High-resolution structure-from-motion models covering 160 km-long surface ruptures of the 2021 MW 7.4 Madoi earthquake in northern Qinghai-Tibetan Plateau

Abstract

The 22 May 2021 MW 7.4 Madoi, Qinghai, China earthquake presented a rare opportunity to apply the modern unmanned aerial vehicle (UAV) photography method in extreme altitude and weather conditions to image surface ruptures and near-field effects of earthquake-related surface deformations in the remote Tibet. High-resolution aerial photographs were acquired in the days immediately following the mainshock. The complex surface rupture patterns associated with this event were covered comprehensively at 3–6 cm resolution. This effort represents the first time that an earthquake rupture in the interior of the Qinghai-Tibetan Plateau has been fully and systematically captured by such high-resolution imagery, with an unprecedented level of detail, over its entire length. The dataset has proven valuable in documenting subtle and transient rupture features, such as the significant mole-tracks and opening fissures, which were ubiquitous coseismically but degraded during the subsequent summer storm season. Such high-quality imagery also helps to document with high fidelity the fractures of the surface rupture zone (supplements of this paper), the pattern related to how the faults ruptured to the ground surface, and the distribution of off-fault damage. In combination with other ground-based mapping efforts, the data will be analyzed in the following months to better understand the mechanics of earthquake rupture related to the fault zone rheology, rupture dynamics, and frictional properties along with the fault interface.

Keywords

• UAV photography
• Earthquake surface rupture
• Structure-from-Motion
• 2021 MW 7.4 Madoi earthquake