Case Study: Earthquake in a Developing Country — Nepal 2015

On 25 April 2015 at 11:56 local time, a magnitude Mw 7.8 earthquake struck central Nepal, with its epicentre approximately 77 km northwest of Kathmandu, near the town of Barpak in Gorkha District. A major aftershock of Mw 7.3 followed on 12 May 2015. Together, these events constitute one of the most devastating tectonic disasters of the 21st century. This case study addresses Edexcel A-Level Geography Enquiry Question 2 (EQ2): Why do some tectonic hazards develop into disasters?

Tectonic Context

Nepal sits on one of the most seismically active zones on Earth — the collision boundary between the Indian Plate and the Eurasian Plate. The Indian Plate converges northward at approximately 4–5 cm/year, driving the uplift of the Himalayas. This convergence is accommodated along a system of major thrust faults, including the Main Himalayan Thrust (MHT) — the primary structure responsible for the 2015 earthquake.

Tectonic Detail	Information
Plate boundary	Continental-continental collision (Indian + Eurasian)
Convergence rate	~4–5 cm/year
Fault type	Thrust fault (Main Himalayan Thrust)
Earthquake magnitude	Mw 7.8 (25 April); Mw 7.3 aftershock (12 May)
Depth	8.2 km (very shallow)
Rupture area	~150 × 50 km
Displacement	Up to 3 m of slip on the fault plane
Epicentre	28.23°N, 84.73°E (77 km NW of Kathmandu)

The earthquake was caused by the sudden release of strain accumulated on a locked segment of the MHT. The shallow depth (8.2 km) concentrated seismic energy near the surface, intensifying ground shaking across the Kathmandu Valley and surrounding districts.

Historical Seismicity

Nepal has a documented history of devastating earthquakes:

Year	Location	Estimated Magnitude	Deaths
1255	Kathmandu	~Mw 7.8	~30,000 (including the king)
1505	Central Nepal	~Mw 8.2	Unknown (extensive destruction)
1833	Kathmandu	~Mw 7.6	~500
1934	Bihar-Nepal	Mw 8.1	~10,700
1988	Udayapur	Mw 6.9	~1,500
2015	Gorkha	Mw 7.8	~8,900

The 1934 earthquake was particularly relevant — it occurred on a different segment of the MHT, and seismologists had identified the Gorkha region as a seismic gap where strain had been accumulating for centuries.

Exam Tip: When discussing the causes of the Nepal earthquake, demonstrate understanding that the event was both inevitable (given the tectonic setting) and foreseeable (seismologists had identified the seismic gap). This raises important questions about why preparedness was inadequate — linking to the PAR model.

Primary Effects

Effect	Detail
Deaths	~8,900 (official figure: 8,891)
Injuries	~22,300
Buildings destroyed	~605,000 (completely destroyed); ~288,000 (partially damaged)
Heritage sites	Dharahara Tower collapsed; Kathmandu Durbar Square severely damaged; multiple UNESCO World Heritage Sites damaged
Ground shaking	MMI IX in Kathmandu Valley; shaking felt as far as Delhi (~800 km)
Landslides	Triggered across mountainous terrain; blocked roads and rivers
Avalanches	Mt. Everest avalanche killed 22 people at Base Camp and Camps I–II

The timing of the earthquake — 11:56 on a Saturday — was significant. Many people were outdoors (Saturday is Nepal's weekly holiday), which likely reduced the death toll compared to a weekday when schools and offices would have been full. The 1934 earthquake, which struck during the monsoon when buildings were weakened by moisture and people were indoors, was more lethal despite a similar magnitude.

Secondary Effects

Avalanches and Landslides

The earthquake triggered extensive mass movements in Nepal's mountainous terrain:

An avalanche on Mount Everest killed 22 people and stranded hundreds of climbers
The Langtang Valley experienced a massive landslide that buried the entire village of Langtang, killing approximately 350 people (including 175 still missing)
Over 2,500 landslides were triggered across the affected area, blocking roads and isolating remote communities for weeks

Disruption to Services

Water supplies contaminated by landslide debris and ruptured pipes
Electricity disrupted across much of the Kathmandu Valley
Communications intermittent — mobile networks overloaded
Roads blocked by landslides, particularly in rural mountain districts
Hospitals overwhelmed — many medical facilities damaged or destroyed

Economic Impact

Economic Effect	Detail
Total damage	~$7 billion (approximately 35% of Nepal's GDP)
GDP impact	Growth fell from projected 4.6% to 3.0% in 2015
Tourism	Visitor numbers fell 32% in 2015 (tourism = ~8% of GDP)
Agriculture	Planting season disrupted; crop losses in affected districts
Remittances	Increased significantly as Nepali workers abroad sent money home

Social Impact

Displacement: 3.5 million people displaced; hundreds of thousands living in temporary shelters
Education: ~32,000 classrooms destroyed; 1 million children out of school
Mental health: PTSD, anxiety and depression widespread; limited psychological support services
Gender-based violence: Reports increased in displacement camps
Child trafficking: Risk increased significantly — border monitoring had to be intensified

Case Study: Earthquake in a Developing Country