A Geologically Unstable Region The Hpakant region in Kachin State is the world's principal source of high-quality jadeite, a pyroxene mineral highly valued as the gemstone jade.%%CITE_1%%%%CITE_2%% The geology of the area is defined by a belt of serpentinized peridotite, a type of ultramafic rock from the Earth's mantle pushed to the surface by tectonic forces.%%CITE_3%%%%CITE_4%% The jadeite is found within these serpentinite bodies.%%CITE_5%% Mining operations involve excavating enormous open pits and removing vast quantities of waste rock, or tailings. This waste material is piled into steep, unconsolidated mounds that can tower hundreds of feet high, dramatically reshaping the area.%%CITE_6%%
These mining practices create a hazardous environment. The host rock, serpentinite, is mechanically weak and highly susceptible to weathering and fracturing. This creates inherently unstable slopes. When combined with the practice of dumping massive, water-retentive piles of excavated waste, the conditions for catastrophic landslides are established. The area experiences frequent slope failures, particularly during the monsoon season when heavy rains saturate the ground.
The Hidden Triggers of Collapse
A significant geotechnical factor in the region's deadly landslides is the presence of pre-existing or "ancient" shear zones within the rock mass. These are zones of weakness, often containing materials like clay or talc, that represent old fault lines or planes where the rock has previously failed. These zones have significantly lower shear strength than the surrounding rock, making them natural slip surfaces. They are often invisible during surface-level site inspection.
The excavation process can expose or "daylight" these weak shear zones on a steep slope. The immense weight of the waste piles increases the shear stress acting along these potential failure planes. The final trigger is often water. Heavy rainfall saturates the soil and waste piles, dramatically increasing the pore water pressure. This pressure counteracts the frictional forces holding the material in place, effectively lubricating the ancient shear zones. Once the shear stress exceeds the reduced shear strength, a landslide is initiated.
A well-documented example occurred on July 2, 2020, when a landslide at the Wai Khar mine killed at least 172 miners. A wave of mud and water, estimated to be 6 meters (20 feet) high, was generated when a massive pile of mining waste collapsed into a lake below. Investigations showed that the failure occurred along critically weak planes in the ground, with seepage and high water pressure being primary causes and not extreme weather alone.