KOTA KINABALU: The recent rockfall at Bukit Sim-Sim in Sandakan highlights a larger issue—unmonitored steep slopes and fractured geological formations that leave Sabah vulnerable to a series of cascading natural disasters.
Universiti Malaysia Sabah geologist Prof Dr Rodeano Roslee explained that many of Sabah’s hillsides, including Bukit Sim-Sim, have gradients exceeding 70 or even 80 degrees and are riddled with natural rock joints and active fault lines.
"These fractures have existed for years. The problem is they have never been properly monitored—and that’s what worries us," he said.
The Bukit Sim-Sim slope is alarmingly close to homes, a main road, and even a temple. In April, a large boulder crashed down from the cliffside onto Jalan Buli Sim-Sim, narrowly missing traffic and prompting temporary road closures.
"These kinds of sites exist all over Sabah," Rodeano said.
"Many steep slopes are near densely populated areas, key road links, and public facilities—making them a constant threat."
Rock falls typically occur along pre-existing joints, and in the presence of active faults, the risk multiplies.
"They can happen on large or small scales, but what we saw (in Sim-Sim) was a large-scale detachment—a clear case of collapse along a fracture system," he explained.
To address these issues, authorities must identify exposed rock formations and hanging boulders along such slopes—not just in Sandakan, but across the state.
While Universiti Malaysia Sabah has conducted research in some areas, Rodeano noted that the Department of Minerals and Geoscience possesses advanced tools such as terrestrial laser scanning and drone mapping technology, which can scan terrain surfaces, simulate rockfall paths, and detect unstable zones.
"The most immediate mitigation is protection. Safety nets and buffer zones must be put in place now to prevent rocks from falling onto roads or nearby homes," he stressed.
Among other high-risk locations are Kampung Gas and Jalan Cecily in Sandakan, the Kundasang highlands, and the Kimanis-Keningau road—all known for unstable terrain.
Rodeano highlighted Sabah’s geological complexity.
"Sabah was formed from the collision of continental and oceanic plates. That’s why we have so many faults and fractures—and active faults can produce earthquakes," he said.
Sabah is unique in Malaysia for being prone to "chain disasters," where one natural hazard triggers another.
"For example, an earthquake can trigger a landslide. A landslide can cause debris flow, and debris flow can lead to flash floods. That’s exactly what we’re seeing in Sabah," he said, citing recent flooding in Kota Belud, not typically known for such events, as a sign of escalating environmental risk.
To prevent future disasters, Rodeano urged a more integrated and data-driven approach to disaster management. He called on technical agencies such as the Department of Minerals and Geoscience, the Malaysian Meteorological Department, the Public Works Department, and local councils to collaborate with universities on slope risk monitoring and mitigation.
"Each agency has a role. What we need now is stronger policy—stronger monitoring guidelines and enforcement—to reduce the impact on people, infrastructure, and lives," he said, adding that local authorities such as Kota Kinabalu City Hall, the Sandakan Municipal Council, and the Ranau District Council should also be involved in coordinated monitoring and response.
