Cebu prone to landslides
PROVINCE OF CEBU, PHILIPPINES -- Cebu needs to learn from Southern Leyte's tragedy and examine areas vulnerable to landslides, such as upland villages in Cebu City, an environment official said Wednesday.
Fresh cracks in the Transcentral Highway and a landslide in Barangay Sinsin are warning signs that the disaster that killed over 150 in Southern Leyte could happen here, said Pedencio Carreon.
Carreon is a City Environment and Natural Resources (Cenro) officer whose jurisdiction covers Cordova town to Sibonga, including Cebu City.
Even as Carreon gave his warning, the cities of Cebu and Mandaue and Consolacion town felt a mild tremor Wednesday, the second in the province in only 17 days.
The disturbance was felt at 10:51 a.m. and registered one on the Richter scale. It lasted three minutes. Its epicenter was somewhere near Barangay Talamban, Cebu City.
Last Dec. 14, a tremor that hit 2.1 on the Richter scale shook the same areas. In both cases, no aftershocks were recorded.
Robinson Jorgio, seismological observer of the Philippine Institute of Volcanology and Seismology, said the tectonic movement was felt only in Barangays Talamban, Bacayan, Villa del Rio and Villa Leyson subdivisions and parts of Mandaue City and Consolacion.
There is no cause for alarm, Jorgio assured.
He explained the two earth movements were caused by limestone filling up cavities below the ground's surface.
Hazard mapping
The environment department has blamed a combination of factors for the Leyte landslides.
These are: record amounts of rain, steep slopes, highly fractured rocks, failure to keep human settlements away from hazardous areas, permanent conversion of forest lands and lack of serious land use planning for disaster-prone areas.
Carreon cited the importance of geological hazard studies in areas where housing projects will be made.
Cebu rests on bedrock sturdier than Southern Leyte's foundations, and does not sit directly on the path of typhoons, said Carreon.
However, the absence of trees and vegetation leaves areas with soft soil cover vulnerable, especially after continuous rains, he added.
This is one reason subdivision developers are now required to get a geo-hazard clearance from the Department of Environment and Natural Resources (DENR) before they are allowed to start working.
Cebu City Planning and Development Officer Paul Villarete has also proposed a geological study of the city, so that government can adopt preventive measures against rain-triggered "soil slips."
"It might cost a considerable amount to the City, but it's worth it, rather than lose lives and properties in calamities," Villarete said in an earlier interview.A geological hazard study includes an examination of the soil, terrain, slopes and the presence of "fault zones" in the area.
Fault zones
Fault zones, or the natural cracks in the earth's mantle, mark the areas where two bedrock plates meet. All earth movements are magnified in these fault zones.
Barangay Punta, San Francisco town in Southern Leyte, where the biggest landslide occurred last Dec. 19, lies at the foot of a huge mountain.
DENR has declared the place a "geo-hazard" area because of the absence of trees on the mountain slopes.
Numerous coconut trees were planted on the mountain slope above Punta, but their roots failed to absorb non-stop rainfall or keep tons of soil from crashing down on the community.
Carreon said coconut trees can hold only the soil within a one-meter radius from its trunk.
"Beyond that, it's already soft soil," he said.
He suggested that narra, mahogany and gmelina trees are ideal for securing mountain slopes.
For an area with a 10-degree slope, with the top to the foot of the slope being used, at least 18 percent of the top portion must be planted with trees, Carreon explained.
Below that, upland agriculture such as coconut plantations and farming may be allowed.
But in most areas in Cebu, houses are built from the top of the slope down to its foot and beyond, which is not good, Carreon warned.
By Oscar C. Pineda with Allan I. Varquez
(Sun.Star Cebu --- January 1, 2004 issue)
A little shade of Environmental awareness...