KOTA KINABALU: The Institution of Engineers (IEM) Malaysia is concerned about the recent earthquake and relatively strong ensuing aftershocks in Ranau and Kundasang from June 5 to 18.
Its president, Datuk Lim Chow Hock, said a number of post-earthquake hazards need to be considered by the authorities when undertaking emergency operations.
Thereafter, the authorities need to initiate post-hazard assessments on the integrity of affected buildings, infrastructures and safety of affected lands before permitting their continued usage, he said in a statement yesterday.
Lim said the four more significant potential hazards are landslides, rockfall, debris laden streamflow and ground liquefaction related damages
According to him, the overburden earth covers on the steep mountains slopes are prone to instability, particularly upon exposure to wet weather to manifest as landslides. They are especially vulnerable given their weakened state following the earthquake.
Rockslides and rockfalls from the loosened rock mass and barely stable boulder piles down the steep mountain sides are inevitable. In the natural setting of the steep slopes, the long run-out of rock slides present great risks to people and properties along the travel paths of the hazards, he said.
Considering the very steep sided terrains, he said debris dams tend to be created by earth and rock slide depositions in the valley floors to block off running waterways. These temporarily-stable debris dams can breach and burst abruptly with terrifying consequences when deluging downstream areas after releasing torrents of mud, boulders and uprooted large trees together with the flood waters to smash through anything obstructing them. They also have the power to gouge into the sidewalls of valleys to induce further landslides and release more debris into the stream channel.
Lim also said that coastal and waterlogged riverine areas may suffer ground liquefaction (where the ground behaves like liquid (e.g. quick sand) when shaken by an earthquake) and related damages leading to excessive settlement of roadways and severe lateral spreading of the ground.
“All the above hazards have proven they are capable of destroying buildings, bridges, homes and farmlands and disrupting essential infrastructures such as power lines, gas lines, road links, telecommunications, potable water supply, healthcare and public order,” he added.
Lim said it would be incumbent upon the authorities to promptly evacuate people from the identified hazard zones to avoid casualties. The evacuees need to be relocated to safety in temporary shelters with food and basic needs until such time that the hazards are identified and addressed; and essential services restored to their communities.
“The post-hazard assessments on the structural integrity of the affected buildings, infrastructures and the safety of the affected land for subsequent usage need to be undertaken by qualified professionals in order to ensure public safety,” he said.
“IEM with its large number of available members possessing the necessary professional qualifications and expertise, is ready to assist the authorities in assessing the affected areas for safe emergency operations and subsequent,” he said.