Sibugay landslide blocks road, strands commuters PDF Print E-mail
Sunday, 28 August 2011 17:11

Incessant rains spawned by tropical storm “Mina” triggered a major landslide in the town of Imelda in  Zamboanga Sigubay at dawn yesterday.
The landslide occurred around 2:00 a.m., along  the steep road cut of the national road in Purok Santan, Barangay San Jose, Imelda, according to the DENR’s Mines and Geosciences Bureau.

A geohazard assessment team from the MGB-9 was fortunately in Buug Municipality when the incident  occurred. The team immediately went to the site to assess and document the situation.

According to the team, the landslide scar measured at approximately 10 meters in length, 10 meters thick, and 15 meters high. Volume of the accumulated landslide debris along the national highway is roughly 1,500 cubic meters and covered almost 50 meters stretch of the highway. This  hindered the flow of traffic, and stranded most of the commuters, cargo trucks, and private  and government vehicles passing the area. Unfortunately, there is no alternative route for  motorized vehicles. Some commuters transferred from one bus to another.

There was no  reported casualty. However, two houses at the foot of the slide were potentially at risk if the accumulated debris will not be removed by the end of the day, MGB-9 said.

One house situated on the top and near the landslide escarpment was identified to be for immediate relocation.
The said landslide was triggered by a weeklong sporadic torrential rain experienced by the locality due to the effect of southwest monsoon, which is further
intensified by tropical storm “Mina”. The heavy downpour also flooded majority of Sibuguey River Basin in the municipality.

Geohazard assessment revealed that the portion of the steep road cuts along the national  highway within the  Municipality of Imelda is highly susceptible to landslide or slump. This  is attributed to several factors such as topography and geologic setting, rainwater, gravity  pull, and manmade intervention.

Terrain and lithologic analyses revealed that the landslide incident is situated along the steep road cut of an elongated hill which is made up of thick, highly weathered/altered, loosely compacted, volcaniclastic deposit. Along the footslope, parallel to the hill is the segment of the meandering Sibuguey River. This type of topography and lithologic make-up is very ideal for landslide to occur. In addition, the weeklong sporadic torrential rain oversaturated the slope materials which resulted to its downward displacement. Construction of the national road along its steep slope and parallel to the segment of Sibuguey River likewise reduced the stability of the slope.

The MGB-9 team recommended a resident on top and near the landslide escarpment to temporarily evacuate to a more stable ground. Future plan would be to relocate his house away from the steep slopes. The residence across the road was also informed to be more vigilant for any eventuality. In addition, the Local Disaster Risk Reduction Management Council (LDRRMC) should prohibit further construction of residential houses within the steep road cut zone both on top slope and along the national road.