MGB-V investigates the reported “soil drop” in Sorsogon

The Mines and Geosciences Bureau in Bicol (MGB-V), in coordination with the provincial office (PENRO) of the Department of Environment and Natural Resources in Sorsogon, recently investigated the phenomenon that local and national media reported as “soil drop” that alleged to have occurred at Sitio Tigkiw-na-Saday in Barangay Tigkiw in Gubat, Sorsogon.

Quoting an investigation report prepared by Senior Science Research Specialist Diosdado R. Dizon of Geosciences Division, MGB-V Regional Director Reynulfo A. Juan said the “soil drop” is actually a mass movement or a landslide.

 “The landslide occurred at Sitio Uban, Barangay Inlagadian in Barcelona not in Barangay Tigkiw in Gubat as reported in the media” Juan said. 

Juan explained the landslide started as a small headward erosion phenomenon along a small tributary of Danlog River in November 2008 and moved en-masse as a debris slump on January 2009 triggered by heavy rains. 

“The landslide occurred at the gully head of a tributary of Danlog River and since the gully head is at the edge of a volcanic footslope, base cutting processes coupled with saturated soil resulted to a ground failure on nearly flat ground” Juan further explained. 

“The slump is 75 meters wide, 150 meters long and 20 meters deep. About 225,000 cubic meters of materials moved downslope towards Danlog River” Juan pointed out.

Juan said some ground cracks were still observed on the crown approximately 1 to 5 meters from the scrap edge and further mass movement could still occur but would be of lesser extent and magnitude.

He said residents near the area should stay away from the site when continuous rains occur.  (LVA Press Release)