Formation and propagation of dust cloud induced by Ultar rock avalanche on April 9, 2018, in Karimabad, Hunza, Pakistan

On April 9, 2018, a massive rock avalanche hit the area of Karimabad, Hunza. Approximately 2Mm(3) of rock mass detached from the source area and traveled a total of 4.88 km. The rock mass deposited along 2000 m length and destroyed the Ultar meadows. The avalanche killed three tourists and resulted in a vast dust cloud that engulfed the entire town of Karimabad in a few seconds. In this paper, we have analyzed the dynamic characteristics of the Ultar rock avalanche and subsequent airblast using a coupled three-dimensional discrete element modeling and computational fluid dynamics approach. Two-way coupling was carried out using an application programming interface that transferred the data between models to simulate the avalanche movement and induced airblast. We have also analyzed the formation and propagation of induced dust clouds based on field investigation, captured video, and climatic conditions. The study concludes that the Ultar rock avalanche's movement lasted 148 s. The average velocity of sliding material was found to be 26.35 m/s. The dynamics of induced airblast were studied along the entire runout path. The maximum velocity of generated airblast along different sections of the runout path was found to be 40 m/s and 35 m/s, respectively, whereas the relative pressure of the blast wave was found to be 0.6 kPa. Furthermore, the results revealed that a low-pressure dust cloud traveled a long distance due to the continuous fragmentation of the sliding material along a steep runout path. The induced dust cloud engulfed the entire town of Karimabad, Hunza, for several hours. This study is expected to help scientists further explore the dynamics of the airblast. It will also help understand the formation and propagation of dust clouds induced by rock avalanches involving excessive fragmentation.

Automated summary

On April 9, 2018, a massive rock avalanche hit the Karimabad area, resulting in the deaths of three tourists and the engulfment of the entire town in a dust cloud. The study analyzed the dynamics of the avalanche and subsequent airblast, as well as the formation and propagation of induced dust clouds. The findings showed that the avalanche lasted 148 seconds, with an average sliding material velocity of 26.35 m/s, a maximum airblast velocity of 40 m/s, a relative pressure of 0.6 kPa, and a long-distance propagation of low-pressure dust cloud due to continuous fragmentation of the sliding material.