Discuss the phenomenon of induced seismicity with reference to underground nuclear testing. Illustrate with a recent case study.

Induced seismicity refers to earthquakes triggered by human alteration of crustal stress — through reservoir impoundment, mining, fluid injection or underground nuclear explosions. Evidence from North Korea's Punggye-ri test site now shows that such tremors can outlive their trigger by years, making induced seismicity a live disaster-management and non-proliferation concern.

How underground nuclear testing induces seismicity

• Direct shock damage: a contained explosion fractures the shallow crust above the cavity; at Punggye-ri most triggered events lay within 1 km of the surface, against ~15 km for natural Korean earthquakes [1].
• Stress redistribution: cumulative damage transfers stress onto neighbouring faults, so dormant faults slip long after the blast [1].
• Delayed decay: unlike natural aftershocks that fade in weeks, activity here intensified, distinguishing induced from tectonic seismicity [1].

Case study: Punggye-ri (Mt. Mantap), 2006–2025

• A 17-year study in Science, using seismic stations in South Korea and north-eastern China, catalogued about 1,400 local earthquakes (2008–May 2025), the bulk after the September 2017 test, North Korea's largest [1].
• Magnitudes rose from ~1.0 to above 3.0 by 2023–24, peaking at M3.4, along two faults seismically silent before testing began [1].
• Events occurred 20–30 km from the site even in 2025, and monitoring succeeded without any on-site access [1].

Indian parallel and policy significance

• Koyna–Warna, Maharashtra is the world's clearest case of reservoir-triggered seismicity: rising pore pressure preceded the 1967 M6.3 earthquake, and the region has stayed active for five decades [2]. India's deep scientific borehole (3 km) under the Ministry of Earth Sciences studies this fault directly [2].
• Testing's persistence strengthens the case for verifiable restraint; India, while refusing the CTBT in 1996 as a treaty banning testing without obliging time-bound disarmament, has observed a voluntary moratorium [3].

Punggye-ri and Koyna together confirm a common lesson: humans can switch a quiet fault on but cannot switch it off. The way forward lies in mandatory triggered-seismicity assessment before large impoundments, sustained regional seismic networks, and pressing for verification-backed, non-discriminatory nuclear disarmament — aligning disaster resilience with India's long-held treaty position.