Darkened skies, even darker tragedies on the grounds in Sabah

In the early weeks of September 2025, the Malaysian state of Sabah witnessed one of its most devastating natural disasters in recent history. A combination of unrelenting monsoon rains, unstable slopes and inadequate infrastructure culminated in a series of catastrophic landslides and flash floods that swept through multiple districts, claiming at least 12 lives, displacing nearly 3,000 people, and severely disrupting essential infrastructure such as electricity and road access.

Authorities warned that as the Southwest Monsoon nears its end, weakening winds are triggering more convective activity, increasing the risk of prolonged thunderstorms and heavy rain, especially in eastern Sabah.

While this disaster has rightly triggered a nationwide outpouring of grief and emergency response, it also serves as a crucial inflection point for examining the growing interplay between environmental mismanagement, urban sprawl, and climate variability in the country.

Tragedy in Penampang and beyond

The most lethal landslide occurred in Kampung Cenderakasih, Inanam, near Kota Kinabalu, where a wooden house was entirely buried under a sudden cascade of earth and debris. 7 individuals, including 4 children, were killed instantly. In the neighbouring district of Papar, another family was lost when a landslide engulfed their home, while Kampung Maragang Tuntul in Ranau reported similar tragedies.

By 16 September, a total of 12 deaths had been confirmed, with additional individuals still missing. Rescue teams have been working tirelessly under treacherous conditions, attempting to locate survivors and recover bodies. Many roads remain impassable, with uprooted trees, collapsed slopes and submerged areas blocking access to remote villages.

Displacement and emergency relief

According to the Sabah Disaster Management Committee, approximately 3,000 people across six districts have been displaced. The worst-hit areas include Penampang, Putatan, Beaufort, Membakut, Papar and Tawau. The government has activated 23 temporary evacuation centres to house those forced from their homes, though overcrowding and limited resources have posed logistical challenges. Prime Minister Datuk Seri Anwar Ibrahim also swiftly approved RM21 million in emergency aid, covering food supplies, medical assistance and one-off payments to families of the deceased.

In a gesture of solidarity and respect for the victims, the state government made the heartfelt decision to cancel Malaysia Day celebrations in Sabah, choosing instead to focus all resources and attention on relief efforts and rebuilding the lives of those affected.

SESB tower collapse: A geotechnical failure

Beyond the human toll, the disaster exposed significant vulnerabilities in Sabah’s infrastructure resilience, particularly in geotechnically sensitive areas. A major incident occurred when Tower 5 on the Kolopis–Segaliud transmission line, operated by Sabah Electricity Sdn. Bhd. (SESB) collapsed following a landslide in Penampang. This structural failure disrupted power to nearly 230,000 consumers, some of whom were left without electricity for over 24 hours.

While temporary measures, such as conductor bridging and the deployment of Emergency Restoration System (ERS) towers, were implemented to partially restore supply, full restoration and reconstruction of the collapsed tower would take up months and cost up to RM3 million.

The tower was located on a hillside where prolonged and intense rainfall likely caused excess pore water pressure buildup within the soil mass. This led to reduced inter-particulate contact and effective stress, consequently compromising the shear strength of the slope material. This condition, coupled with possible inadequate or interrupted drainage (e.g. blockages), may have triggered progressive failure along a critical slip surface in the soil mass. The soil movement would have been imperceptible in the torrential rain, ultimately resulting in a rotational landslide that undermined the structural foundation of the transmission tower.

This failure highlights the critical importance of comprehensive geotechnical investigations during infrastructure planning, including subsurface profiling, slope stability analysis, and hydrogeological assessments. In particular, infrastructure sited in hilly or weathered tropical terrain must incorporate robust slope stabilisation measures, such as retaining systems, subsurface drainage, and reinforced earth structures, to mitigate risks associated with progressive failure, piping, and deep-seated rotational slides.

In addition, infrastructure design in geohazard-prone regions should incorporate real-time geotechnical monitoring systems, including inclinometers (displacement sensors), piezometers (groundwater level detection), and automated total stations (land mass movement surveillance), to enable continuous assessment of slope movement and subsurface conditions.

These systems should be calibrated against site-specific trigger thresholds, derived from detailed geotechnical and hydrogeological investigations, including soil strength parameters, groundwater conditions, and slope geometry. In this case, the intense and prolonged rainfall resulted in excess surface runoff, which exceeded the capacity of the existing drainage infrastructure, leading to elevated pore water pressures and reduced slope stability.

Furthermore, designing with a higher Factor of Safety (FoS), particularly under conditions of increasing rainfall intensity and climate-induced variability, provides critical buffer time. This enhanced FoS not only accounts for potential degradation in material strength and pore pressure buildup, but also facilitates early warning dissemination, enabling timely mass evacuation and structured emergency response planning informed by predictive failure models and real-time data interpretation.

Amplification by human factors

On a separate note, acknowledging that landslides and floods are not new to Sabah, both their frequency and severity have noticeably increased in recent years. A 2024 report by the Malaysian Meteorological Department indicates that East Malaysia has experienced a 20-30% rise in average annual rainfall over the past 2 decades. This trend aligns with global climate models predicting more intense and erratic monsoonal rainfall patterns as a consequence of climate change. However, attributing the recent disaster solely to meteorological factors oversimplifies the issue.

From a civil engineering perspective, a range of anthropogenic pressures have amplified the region’s susceptibility to slope failure and flooding. These include (1) deforestation, which reduces root reinforcement and accelerates surface runoff; (2) extensive hill-slope development on marginal or unstable terrain; and (3) unregulated urban sprawl that overwhelms natural drainage systems.

In areas like Penampang, numerous residential and commercial developments have been constructed on steep slopes, often without due consideration of geotechnical site investigations, slope reinforcement techniques, or subsurface and surface drainage systems. The absence or failure of such engineered slope protection measures, including retaining walls, soil nails, gabion structures and drainage channels, can lead to a reduction in slope factor of safety, especially under conditions of prolonged rainfall, where pore water pressure increases and leads to a loss in shear strength.

Apparently, inadequate planning, coupled with poor regulatory enforcement, has transformed natural slopes into high-risk zones for landslides and flash floods, turning what should be manageable environmental risks into tragic and largely avoidable disasters. This not only reflects a failure in technical oversight but also highlights a deeper disconnect from the principles of sustainable development, which demand that environmental, social, and economic considerations be balanced in land-use decisions.

A watershed moment for all

The Sabah disaster starkly illustrates how the convergence of intensified climate patterns and human activities can transform natural hazards into catastrophic events. While relentless rainfall served as the spark, it was arguably years of unchecked development, poor land-use planning and systemic neglect of environmental safeguards that turned the natural hazard into a human catastrophe.

Without integrating long-term resilience, ecological preservation and risk-informed urban planning, development in vulnerable regions will continue to jeopardize lives, strain public resources, and undermine the very sustainability goals meant to guide national progress.

Moving forward, Sabah’s resilience hinges on integrating rigorous geotechnical assessments, enforcing sustainable land-use policies, and investing in climate-adaptive infrastructure. Only through a holistic approach that addresses both natural and anthropogenic risks can the state and nation hope to mitigate future tragedies and protect its communities.