October 6, 2021 Earthquake: Balochistan Province, Pakistan

At least 21 people killed, 300 injured and 15 miners missing; more than 1,000 homes damaged or destroyed; landslides blocked roads and power outages occurred in the Harnai area.

On October 6, 2021, an M5.9 earthquake occurred in the north of the Balochistan province of Pakistan, approximately 100 km east of the city of Quetta. The earthquake occurred at shallow crustal depths (approximately 9 km) as the result of thrust faulting on either a fault dipping shallowly to the north, or a fault dipping steeply to the south. The earthquake mechanism, depth, and location are consistent with the earthquake having occurred on or near the shallowly northward dipping plate boundary between the India and Eurasia plates. At the location of the earthquake, the India plate moves north at 29 mm/yr relative to the Eurasia plate.

The October 6, 2021 earthquake occurred near the western edge of the Sulaiman Mountains, a U-shaped active fold-and-thrust belt mountain range in central Pakistan formed at the boundary between the converging Eurasia and India plates. The Sulaiman Mountains are characterized by intense faulting and folding of a thick package (approximately 10 km thick) of sedimentary rocks that are decoupled from underlying crystalline rock of the India plate by a nearly horizontal thrust fault, or decollement, that dips northward beneath the Eurasia plate.

Moderate magnitude (M6+) earthquakes are common in the vicinity of the October 6 earthquake; 21 earthquakes of M6 or larger occurred within 250 km of the October 6 earthquake in the past 100 years. Notably, an M7.1 thrust earthquake with similar faulting characteristics to the October 6 earthquake occurred 40 km to the southeast on February 27, 1997. The 1997 earthquake led to ~100 casualties and strong shaking in Quetta. West of the Sulaiman Mountains, an M7.2 earthquake occurred on August 27, 1931 75 km to the southwest of the October 6 earthquake. An M7.5 earthquake on May 30, 1935 located 205 km southwest of the October 6 earthquake caused widespread destruction in Quetta and approximately 20,000 fatalities.

Reference #1053:

Tectonic Summary

On October 6, 2021, an M5.9 earthquake occurred in the north of the Balochistan province of Pakistan, approximately 100 km east of the city of Quetta. The earthquake occurred at shallow crustal depths (approximately 9 km) as the result of thrust faulting on either a fault dipping shallowly to the north, or a fault dipping steeply to the south. The earthquake mechanism, depth, and location are consistent with the earthquake having occurred on or near the shallowly northward dipping plate boundary between the India and Eurasia plates. At the location of the earthquake, the India plate moves north at 29 mm/yr relative to the Eurasia plate.

The October 6, 2021 earthquake occurred near the western edge of the Sulaiman Mountains, a U-shaped active fold-and-thrust belt mountain range in central Pakistan formed at the boundary between the converging Eurasia and India plates. The Sulaiman Mountains are characterized by intense faulting and folding of a thick package (approximately 10 km thick) of sedimentary rocks that are decoupled from underlying crystalline rock of the India plate by a nearly horizontal thrust fault, or decollement, that dips northward beneath the Eurasia plate.

Moderate magnitude (M6+) earthquakes are common in the vicinity of the October 6 earthquake; 21 earthquakes of M6 or larger occurred within 250 km of the October 6 earthquake in the past 100 years. Notably, an M7.1 thrust earthquake with similar faulting characteristics to the October 6 earthquake occurred 40 km to the southeast on February 27, 1997. The 1997 earthquake led to ~100 casualties and strong shaking in Quetta. West of the Sulaiman Mountains, an M7.2 earthquake occurred on August 27, 1931 75 km to the southwest of the October 6 earthquake. An M7.5 earthquake on May 30, 1935 located 205 km southwest of the October 6 earthquake caused widespread destruction in Quetta and approximately 20,000 fatalities.

Reference #13063:

A powerful earthquake collapsed at least one coal mine and dozens of mud houses in southwest Pakistan early Thursday, killing at least 23 people as the death toll continued to creep higher. At least another 200 people were injured, an official said. The death tally was expected to rise even further as crews searched in the remote mountainous area, said Suhail Anwar Shaheen, the local deputy commissioner.

At least four people were killed when the coal mine in which they were working collapsed, said Shaheen, citing coal miners in the area. As many as 100 homes also collapsed, burying sleeping residents inside.

Pakistan’s southwestern Baluchistan lies on a seismically active region, according to the provincial disaster management authority. The worst earthquake, in 1935, destroyed the provincial capital of Baluchistan and killed more than 35,000 people.

Reference #13065:

An earthquake with a magnitude of 5.9 and 15 km depth struck Harnai district, Balochistan on 7th October 2021 at 3:02 am. As a result, 42 people died and 229 were reported injured and 409 houses were completely or partially damaged as per initial reports.

Reference #1250:

Deaths 21; 300 injured