THE Institution of Engineers, Malaysia (IEM) is concerned about the recent earthquake and relatively strong ensuing aftershocks at the Ranau/Kundasang area from June 5 to June 18.
A number of post-earthquake hazards need to be considered by the authorities when undertaking emergency operations.
After that the authorities need to initiate post-hazard assessments on the integrity of affected buildings, infrastructure and safety of the affected lands before permitting their continued use.
The four more significant potential hazards are:
1) Landslides: The overburdened earth covers on the steep mountain slopes are prone to instability, particularly upon exposure to wet weather and can manifest as landslides. They are especially vulnerable given their weakened state after the earthquake.
2) Rockfall: 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 rockslides presents great risks to people and properties along the travel paths of the hazards.
3) Debris-laden streamflow: Considering the very steep terrain, debris dams tend to be created by earth and rockslide depositions in the valley floors, blocking off running waterways.
These debris dams can breach and burst abruptly, with terrifying consequences, 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.
4) Damages related to ground liquefaction: Coastal and waterlogged riverine areas may suffer ground liquefaction, where the ground behaves like liquid (quicksand, for example) when shaken by an earthquake, and related damage leading to excessive settlement of roadways and severe lateral spreading of the ground.
All the above hazards have proven to be 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.
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 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, infrastructure and the safety of the affected land for subsequent usage need to be undertaken by qualified professionals in order to ensure public safety.
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 reconstruction works.
DATUK IR LIM CHOW HOCK
The Institution of Engineers, Malaysia
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