Landslides occurred in the upland areas of barangays Calog, Sibalom and Botbot, Hamtic, Antique in the month of July and August this year, reported the Mines and Geosciences Bureau Region 6 (MGB-6) who conducted an investigation of the area on August 17-18, 2009.
The Municipal Disaster Coordinating Council of Hamtic and the Provincial Disater Coordinating Council of Antique requested MGB-6 to conduct the investigation.
MGB-6 recommended for the relocation of affected residents in the said barangays. Dr. Leilanie Suerte, geologist of MGB-6 said the factors that make an area vulnerable to landslides are present in the upland areas of Brgy. Calog, Sibalom and Brgy. Botbot, Hamtic Antique. Other neighboring barangays with the same geological characteristics of these two barangays are also susceptible to landslides.
According to her, the type of soil and rock covering the upland area of Brgy. Calog, Sibalom and the saturation of heavy rainfall caused the landslides.
The upland hills of Brgy. Calog is made of loose materials such as sandstone, siltstone, and mudstone belonging to the Lagdo Formation. Further, these upland areas have indications that active soil creep is occurring in these hills.
Residents of barangay Calog confirmed that they observe numerous cracks in the upland areas and landslides at the head of the Maganhupan Creek after the continuous and heavy rain during the months of July and August.
In her report, Dr. Suerte added that flashflood, sheet floods and debris flow may also occur during continuous and heavy rainfall in Brgy. Calog proper because Maganhupan Creek passes through it.
Brgy. Millamena located downstream of Brgy. Calog could also be affected by these flashfloods and debris flow coming from Brgy. Calog.
Brgy. Botbot in Hamtic was already assessed by MGB-6 as highly prone to landslide back in 2008. According to Dr. Suerte, landslides will most likely to happen in the barangay because of its location, topography, lithology, abundant groundwater in the area and the presence of active soil creep.
Last July 11, 2009, residents of Brgy. Botbot felt two earthquakes. They said that household items were shaking during the earthquake. According to the residents, it was also raining heavily for several days during and after the earthquakes.
All these factors and the geographical characteristics of the barangay caused the landslides to happen.
In 2008, MGB-6 gave landslide threats and advisories to Brgy. Botbot after its geohazard assessment of the area. MGB-6 recommended for landslide identification, monitoring and mitigation.
There are also other reported landslides in Sibalom near Sitio Rizal, Brgy. Valintin Grasparil, Sitio Igtangway, Brgy. Igparas, Sitio Langka Brgy. Bulalacao. In Hamtic, landslides were also observed in barangays Casalngan, Pamandayan, Del Pilar and Cantulan.
The MGB has conducted a rapid geohazard assessment of the whole Antique Province and provide the results to the provincial government. MGB-6 also gives an advisory to the barangays after assessing them.
MGB-6 reiterated to the Provincial Disaster Coordinating Council of Antique prior recommendations to the local government units to lessen the negative effects of landslide and flooding to susceptible barangays.