After a five-hour downpour in Calabar, the Edim Otop neighbourhood near Atimbo area of the state capital renowned for flood problems was completely submerged leading to the occurrence of a landslide which left in its wake casualties, including the entire family of one Mr Amos.
Landslides are classified as mass movement of rock, debris, and soil down a slope of land. While landslides are a naturally occurring environmental hazard they have recently increased in frequency in certain areas due to human activity.
Although there are many different causes of landslides, they all have two things in common. They are the result of the failure of the soil and rock materials that make up the hill-slope and they are driven by gravity.
A sub-category of landslides, mudslides are rivers of rock, earth and other debris that are saturated with water, according to the U.S. Geological Survey (USGS). Mudslides can be slow- or fast- moving, though they tend to grow in size and momentum as they pick up trees, boulders, vehicles and other materials.
The incident in Edim Otop was not the first in the state or the casualty the only recorded in the state of late.
The incident this time especially affected one Mr Amos who hails from Obio Ediene in Ikono LGA of Akwa Ibom State. He said, “I bought the mud house from the owner who wanted to dispose of it in 2010 and I rebuilt it with cement blocks.” Amos claimed that he never heard that government warned people not to live in the area.
He narrated how the incident happened: “I was at home with the children when this thing happened. My wife and her mother just returned from the church that particular moment. As soon as they entered the house, the rain and the flood became very serious. And that very moment the house caved in and collapsed on them. I was unconscious even though I was aware of hundreds of people milling around. I saw several men in uniform. I was out of this world.”
A geologist with the Nasarawa State University, Mr Bassey Essien commented on the situation, and listed possible reasons that could have led to it. He listed four possible causes as the main factors that led to the calamity. These, he said, include geological, morphological, (that is, its form and structure), human and physical.
He said: “These could have led to such devastation. Morphological causes would include slope angle, uplift, rebound, fluvial erosion, wave erosion, glacial erosion, erosion of lateral margins, subterranean erosion, vegetation changes, among others. For geological, factors would include weathered materials such as heavy rainfall, sheared materials, jointed or fissured materials, adversely orientated discontinuities, permeability contrasts, material contrasts, rainfall and snow fall, earthquakes, and working of machinery.”
Essien said if these were not taken into consideration, then the pronounced possibility became imminent for a land-scale landslide at such terrain.
For a landslide to occur, the geologist said physical causes would have entailed intense rainfall, prolonged precipitation, rapid snow melt, rapid draw down, earthquake, volcanic eruption, thawing, freeze – thaw, ground water changes, soil pore water pressure, surface runoff, seismic runoff, seismic activity and soil erosion.
According to the expert, the human causes would include activities such as excavation, loading, land use changes and water management while adding that mining and quarrying activities also gravely impact against the soil. “If there is vibration, water leakage, deforestation and pollution, there is the certainty that landslide can occur in such an environment”, he said.
An inventory of landslides and associated mass wasting events in Nigeria for risk assessment and land use planning by Theophilus Davies and A. O. Solomon of the University of Jos noted that landslides in Nigeria cause several fatalities per year. “They pose threats to settlements and structures, and often result in catastrophic damage to highways, waterways, pipelines and farmland.”
