As rescuers raced against time to save thousands believed missing in a massive landslide in the eastern Philippines, experts said yesterday it was an accident waiting to happen.
Government geologists have long identified as "unfit for dwelling" several areas in the province of Southern Leyte, 675km southeast of Manila, including the village of Guinsaugon, which was wiped out by the landslide on Friday.
In a geohazard assessment after a similar tragedy struck in December 2003, leaving some 300 people dead or missing, the Bureau of Mines and Geosciences warned that Southern Leyte's natural and geological features make it susceptible to landslides and floodings.
"We have advised the local government [in Southern Leyte] to immediately evacuate the people in specific areas including the area hit by the latest landslide, because it is unfit for dwelling," an official from the Department of Environment and Natural Resources told the Philippine Star newspaper.
"There should be no community existing there," the official added.
Most towns in Southern Leyte are surrounded by a steep mountain range as high as 800m above sea level in some areas. The steep slopes are often planted with coconut trees, whose shallow root systems do not contribute to soil stability.
Monsoon rains and typhoons also batter the province throughout the year.
"Numerous faults and major fractures cut through the major rock units," according to the geohazard assessment of the Bureau of Mines and Geosciences. "Because of these, the rocks are badly broken or fragmented. The fragmented rocks are prone to weathering and erosion."
"When continuous rainfall occurs, water seeps into the fractures of the broken rocks and promotes the deterioration of the rock mass," it added.
The bureau noted that if the amount of rainfall was limited in volume and duration, the soil and rock materials could easily absorb the water. But if the rain was excessive, the rock and soil materials would become saturated and cause landslides.
And this was exactly what happened in Guinsaugon.
After several days of torrential rains, a huge portion of Mount Can-abag collapsed and unleashed a waterfall of mud, boulders and coconut trees into the farming village of Guinsaugon, flattening houses and other structures.
Nearby villages have now been evacuated amid continuous rains that might trigger similar accidents, officials said.
According to the weather bureau, 500mm of rain fell on Southern Leyte since last week, up from an average rainfall of 127mm, loosening the soil on the mountain.
Witnesses said it was like the mountain exploded before the landslide.
Aside from the torrential rains, environmentalists also blamed rampant illegal logging, mining and other ecological excesses for such disasters.
"Our country is in a state of ecological crisis, aggravated by La Nina [a phenomenon characterized by unusually heavy rains and cold weather]," said Senator Jamby Madrigal. "We are now at the mercy of environmental disasters."
Southern Leyte Congressman Roger Mercado said illegal logging that started in the 1970s in the province had weakened the soil on the slopes of the mountain range.