- The Geological Survey of Tanzania (GST) says what was happening at Kunduchi was a condition known as liquefaction, trashing assumptions that there could be a probability of a volcanic eruption.
Dar es Salaam. Some residents of Kunduchi suburb in the commercial capital live in a state of panic while awaiting the government to allocate them new plots due to the liquefaction of the land upon which their houses are built.
Oozing mud-slides have been spreading in the area so much so that at least nine houses have collapsed while tens of other houses have cracks, some of which are so serious that makes it dangerous for people to continue residing in them (the houses).
“At first, we thought it was due to poor housing because the mud-slides started off as water leaks. This was to be followed by cracks and ultimately, houses collapse,” Ms Mariam Mshindo, one of the victims of the oozing mud-slides told The Citizen.
A close look at the area reveals that the mud-slides seem to evolve from ‘Jeshini stream’ but were spreading fast to other areas within Kunduchi Ward, Kinondoni District in Dar es Salaam. Ms Mshindo - who has been living at Kunduchi, Mtongani for over fifteen years - took time to described how the first house tumbled in the area three months ago.
“There were water leaks which we thought were linked to heavy rainfall, but one day my neighbour came home to find a collapsed toilet and that was how we realized that there could be more than met our eyes,” she detailed.
That unfortunate incident of the collapsing of the toilet forced Ms Mshindo’s neighbor to relocate to another location within Dar es Salaam. At that point, little did they know that by relocating, they were actually saving their lives from a total house tumbling of the house.
“Within one night, the whole house tumbled and to our surprise, it kept sinking even after tumbling,” she explained, pointing to a place that used to be a football pitch but which later started forming a hill at the center which now looks like the epicentre of the mud-slides in the area.
Mr Abdulrazak Mkalamari, who is also a residing at Kunduchi, said they (residents) started taking the situation seriously when a child and a cow almost drowned in one of the places affected.
“We were lucky to save both the girl and the cow, but with the spread of the mud, the whole community is nervous about the incidents that may go unnoticed,” he said.
Mr Juma Singano, who has been at the Kunduchi since 1975, finds the going tough as he ponders on his next course of action.
“We can only ask that the government should tell us where to go….I have 20 children and I do not know where to go with them,” he said.
The Geological Survey of Tanzania (GST) says what was happening at Kunduchi was a condition known as liquefaction, trashing assumptions that there could be a probability of a volcanic eruption.
“Such an incident cannot be linked to a volcanic eruption. After all, Dar es Salaam’s geological setting puts the city at a position that is far from any threat of a volcanic eruption,” said a senior geologist of GST, Mr Gabriel Mbogoni.
According to him, volcanic eruptions usually occur along rift valleys or in some tectonic zones.
“What happened at Kunduchi Mtongani was a normal liquefaction which occurs when seismic forces (either natural or man-made) affect saturated, loose, granular layers, forcing the loose soil structure to contract and in the process, generating excess pore water pressure, accompanied by a reduction in soil strength,” he said.
Available literature say that soil liquefaction occurs when a saturated or partially saturated soil substantially loses strength and stiffness in response to an applied stress such as shaking during an earthquake or other sudden change in stress condition, in which material that is ordinarily a solid behaves like a liquid. Liquefaction is most likely to happen in reclaimed land. Areas with shallow water tables and close to the sea or rivers are also susceptible to liquefaction.
When liquefaction occurs, the strength of the soil decreases and, the ability of a soil deposit to support foundations for buildings and bridges is reduced.
Liquefied soil also exerts higher pressure on retaining walls,which can cause them to tilt or slide. This movement can cause settlement of the retained soil and destruction of structures on the ground surface.
Increased water pressure can also trigger landslides and cause the collapse of dams.
According to Mr Mbogoni, such incidences were also common in some parts of Shinyanga, Singida and Dodoma regions.
The Dar es Salaam Regional Commissioner, Mr Aboubakar Kunenge has directed the residents around the areas affected by liquefaction to immediately leave for safety reasons.
“I order the residents to shelter in other safe areas while the government continues to conduct research to determine the size of the affected area,” he said.
RC Kunenge has also instructed the Director of Kinondoni Municipality to place hazard signs in the affected areas during the research period.
He said the government is looking for a way to provide land (plots) to some affected people.
By Alfred [email protected]@tz.nationmedia.com