Tag Archives: land subsidence

Land subsidence causing San Francisco Tower’s Sinking Seen From Space?

This report by Associated Press summarizes how many factors can come into play when an engineering structure is failing or is responding to forces unleashed  on it after it has been completed. The forces could be man-made such as ground water abstraction or withdrawal or it could be due to structural geologic features that were overlooked or underestimated during the planning stages. The problem of the San Francisco tower should be a good interdisciplinary case study for students of building technology, geosciences and other related fields.

This blogger has discussed the recurring problem of collapsed  buildings in Lagos, Nigeria which could be due to uncontrolled withdrawal of ground water, poor geotechnical investigation before construction, poor building material and poor supervision by site engineers (https://weircentreforafrica.com/2012/11/24/collapsed-buildings-in-nigeria-thoughts-on-the-probable-causes/)

DEPO ADENLE, November 2016


By JOCELYN GECKER, Associated November 29, 2016


© The Associated Press The image provided by the European Space Agency ESA on Thursday, Nov. 24, 2016, shows the Millennium Tower in San Francisco on the base of modified Copernicus Sentinel satellite data. The European Space Agency has released satellite…



SAN FRANCISCO — Engineers in San Francisco have tunneled underground to try and understand the sinking of the 58-story Millennium Tower. Now comes an analysis from space.

The European Space Agency has released detailed data from satellite imagery that shows the skyscraper in San Francisco’s financial district is continuing to sink at a steady rate — and perhaps faster than previously known.

The luxury high-rise that opened its doors in 2009 has been dubbed the Leaning Tower of San Francisco. It has sunk about 16 inches into landfill and is tilting several inches to the northwest.

A dispute over the building’s construction in the seismically active city has spurred numerous lawsuits involving the developer, the city and owners of its multimillion dollar apartments.

Engineers have estimated the building is sinking at a rate of about 1-inch per year. The Sentinel-1 twin satellites show almost double that rate based on data collected from April 2015 to September 2016.

The satellite data shows the Millennium Tower sunk 40 to 45 millimeters — or 1.6 to 1.8 inches — over a recent one-year period and almost double that amount — 70 to 75 mm (2.6 to 2.9 inches) — over its 17-month observation period, said Petar Marinkovic, founder and chief scientist of PPO Labs which analyzed the satellite’s radar imagery for the ESA along with Norway-based research institute Norut.

“What can be concluded from our data, is that the Millennium Tower is sinking at a steady rate,” Marinkovic said in a telephone interview Monday from The Hague, Netherlands.

The data detected a small slowdown this summer but one that needs further analysis, he said, and does not change the overall data. “There is quite a steady subsidence.”

The Sentinel-1 study is not focused on the Millennium Tower but is part of a larger mission by the European Space Agency tracking urban ground movement around the world, and particularly subsidence “hotspots” in Europe, said Pierre Potin, Sentinel-1 mission manager for the ESA.

The ESA decided to conduct regular observations of the San Francisco Bay Area, including the Hayward Fault, since it is prone to tectonic movement and earthquakes, said Potin, who is based in Italy.

Data from the satellite, which is orbiting about 400 miles (700 kilometers) from the earth’s surface, was recorded every 24 days.

The building’s developer, Millennium Partners, insists the building is safe for occupancy and could withstand an earthquake.

The developer’s spokesman PJ Johnston said he had no direct comment on the satellite data but issued a statement saying that the Millennium Tower is a state-of-the-art building that was “designed and constructed to the extraordinarily high standards” mandated by San Francisco.

He reiterated the developers’ blame for the tower’s problems on the city’s construction of an adjacent railway station, which they say removed ground water from beneath the Millennium Tower that caused it to sink and tilt.

The city agency, the Transbay Joint Powers Authority, blames the building’s “inadequate foundation” which is not anchored to bedrock. The tower is supported by piles driven 60 to 90 feet into landfill.

Engineers hired by the building and its developers have drilled deep holes around the building to test soil samples to determine if the building has stopped sinking, and if there’s a way to fix it.

One of the building’s tenants, Jerry Dodson, says that developers have given tenants the impression that the sinking was slowing and stopping.

“To have the space agency looking at it debunks what (developers) have put out there. Now we know it’s continuing to sink at an accelerated rate,” said Dodson, an attorney who has helped organize homeowners lawsuits. “I can tell you that satellite data is way more accurate that digging in the dirt.”



Collapsed Buildings in Nigeria: Thoughts on the probable causes.

Thoughts on the probable causes of building collapse in Nigeria.

By Depo Adenle

There seems to be an increase in building collapse in Nigeria especially in Lagos State. The following thoughts come to mind whenever a building collapses on estates built along Nigeria’s coastline. The recent occurrence at Jakande Estate in Isolo as reported below by Sahara Reporters and The Punch calls for concern.

These thoughts can be divided into two major groups – construction and handing over stage, and post-construction development stage.

Construction and Handing Over Stage:

Was the estate built on reclaimed land from old landfills? – Isolo houses about three and half decades old Oke-Afa dump site, which was recently
closed down for commercial dumping due to expiration of
age (30 years). What kind of material sits on top of the recent sediments that lies under the landfill materials when this area was reclaimed – is it highly compressible ? What type of foundation was used and how suitable is this foundation for the kind of engineering soils at the site? What type of loading was envisaged and what was the loading like before collapse? What is the quality of building material used as compared to engineering specification? Who signed off on the structural soundness of the buildings before residents moved in?

Post Construction Development Stage:

What kind of loading existed just before the collapse of the buildings? What was the magnitude of groundwater withdrawal within the estate and in areas that adjoin the estate?

The latter is important because groundwater abstraction is not yet regulated in the country. Industries pump as much as they need without any concern for the impacts these withdrawals have on other users because there is no regulation guiding groundwater abstraction.

It has been reported that the water demand is very high in Lagos Metropolis and this has led to groundwater over-use and land subsidence which has a strong effect on houses and other infrastructures.

Land subsidence is not limited to Lagos as it has been reported that it occur s particularly in the coastal areas of Nigeria (Environmental statistics: Situation in Federal Republic of Nigeria; Being Country Report Presented at the Workshop on Environment Statistics Held in Dakar, Senegal 28th February – 4th March 2005).

Meanwhile, there is a ‘Nigerian Water Law’ which  is yet to be enacted.

As the Punch report has revealed, Nigeria’s emergency agencies are usually not up to the task when disasters strike, and with repeated collapse of structure, this needs to be urgently addressed.

And since the Lagos State coastal area is the place constantly in the news for these calamities, the authorities in the State need to respond to the issues raised above as well as monitor the magnitude and distribution of groundwater abstraction.  In addition, strict adherence to engineering designs must be enforced so that building contractors do not cut corners in use of materials or refuse to keep to specifications.

One hopes that the many lives being lost over and over again should ginger the Lagos State government to act because they are needless loss of lives.

Lagos Building Collapse Update: Occupants of All Neighboring Buildings Ordered to Vacate their Premises within 48 Hours

Sahara Reporters, New York

November 21, 2012

The Lagos State Building Control Agency [LASBCA] has ordered all occupants of structures near the collapsed building at the Jakande Estate, Isolo in Lagos State to vacate their premises in 48 hours.

Most buildings within the vicinity have structural weaknesses and signs of imminent collapse.

Police officers who visited the site promised the residents that they would be temporarily rehabilitated, but where they are to be relocated had not been announced as of the time of filing this report.

kids died in the collapse and their mother was also seriously injured.  She is receiving treatment in a hospital.


Lagos building collapse kills two sisters, injures mother

Kunle Falayi and Temitayo Famutimi

The Punch, November 22, 2012 by

Two sisters killed in Lagos building collapse –Pages 4&5
| credits: File copy

Two sisters – Toyin and Bukky Coker – were killed on Wednesday when a part of the two-storey building they lived in at M20, Jakande Low Cost Housing Estate, Isolo, Lagos, collapsed.

Their mother identified simply as Iya Coker was injured.

Three out of the six flats on one of the two wings of the building completely collapsed at about 12:05am.

It was learnt  that the deceased and their mother lived on the first floor.

PUNCH Metro learnt that Toyin, was a 30-year-old medical doctor, while Bukky recently finished her national youth service. Both sisters were graduates of the University of Lagos.

One of the survivors, Ahmadu Omoniyi, who lived on the ground floor of the building said he informed Mrs. Coker of the impending danger at about 11.40pm  on Tuesday night when he heard the building cracking.

He said, “When I got home on Tuesday evening, I observed that sand and stone were falling off from the walls and the decking. I informed the caretaker immediately. I moved into the apartment in September.

“Around 11pm, I suddenly woke up feeling uneasy.  I roused the other two people staying with me and asked them to start packing vital things while I went to Mrs. Coker’s place to draw her attention to the situation.

“When I got to her floor, she answered me from inside saying, ‘God will see us through till tomorrow’. Nobody stayed on the second floor, so, I joined my other flat mates downstairs.

“To my utmost surprise as soon as we removed our vitals documents from our apartment and moved like three steps away, the building collapsed. It was God that saved us because the whole place went down.”

How woman, corpses were found –Neighbour

A resident of the area, Opeyemi Fagun, said the sound of the collapsed building drew neighbours’ attention to the scene.

He said despite starting the emergency operation started the incident happened, Coker could not be rescued until after about four hours.

He said, “We heard the woman saying, ‘please help, please help’ but we couldn’t locate her on time because of the amount of debris that had fallen all over the place.

“We finally located her at about 4am where a wooden cupboard had fallen over the lower part of her body on the bed she slept. Meanwhile, the cupboard prevented the hard core debris from falling on her.”

It was learnt that calls placed by residents to the number of her two daughters after their mother had been rescued rang out.

Fagun explained that Coker could not also give a comprehensive account of the number of people in her apartment as she seemed to be in shock at the time she was being taken to hospital.

Fagun said, “We kept on searching the debris. We later sighted a leg, which turned out to be that of Bukky under the debris. Toyin’s corpse, which was also buried under the debris was also sighted.

“Both of them were found dead under the debris. We concluded the search and rescue at about 5am after Toyin’s body was recovered. Government emergency officials later started coming around some minutes to six blaring sirens all over the place.”

General Manager of the Lagos State Emergency Management Agency, Dr. Femi Oke-Osanyintolu, said the bodies of the sisters had been taken to the morgue.

When one of our correspondents visited the scene, oficials of the Lagos State Building Control Agency were seen marking the buildings on the M Zone of the estate for demolition.

‘Govt officials ignored our calls’

Survivors of the incident told one of our correspondents that emergency officials, who were alerted to the impending disaster did not come.

A resident, Daramola Victor, told one of our correspondents that about 11.40pm, it was noticed that the walls were about to give way.

He said, “I live in the second wing. But we noticed that the other wing was cracking and we called the National Emergency Management Agency, Lagos State Emergency Management Agency and fire service on the phone. Only the Red Cross came later after the collapse.

“All these agencies are here now acting as if they are doing something useful. They could have saved lives if they came when we called on them.”

He said when he noticed that one of the wings of the building had collapsed, he rushed back into his apartment and evacuated his family.

“I really don’t know where to go now. All our properties are outside. Neither LASEMA nor NEMA is giving us any assistance in this direction,” he said.

State officials lied –Residents

Residents of the buildings at the site that have now been tagged “distressed” and sealed by the  Lagos State Building Control Agency, said no effort was made in the past by government officials to test the state of the buildings in the estate.

Earlier, the Commissioner for Housing, Mr. Bosun Jeje, who was at the site briefly, had said the buildings were “inspected frequently by our engineers.”

He said, “This is a responsible government, whenever anything like this happens government always ensures that those who are affected are taken care of.

“Government will offset the medical bills of victims who are receiving treatment in the hospital. As you can see, the buildings have been marked for demolition because they are weak.”

Managing Director, Lagos State Property Development Corporation, Biodun Oki, also said the residents had been given notice to quit the buildings prior to the collapse.

“The markings of the distressed buildings had been before now and even some of them moved out before now,” Oki said.

But residents said the buildings were marked for demolition immediately after  Wednesday’s incident. They claimed there was no prior warning from government agencies.

One of our correspondents noticed officials of the LASBCA marking the buildings on the M Zone of the estate at about 9am on Wednesday.

An angry resident, who pleaded anonymity said, “If anybody tells you that they had inspected these buildings before, they are only lying. We had called on the government at different times to compel the owners of the buildings to renovate them but they did not take any step.

“I did the renovation of my own apartment when I moved in. I would have packed out of the apartment if not because I am financially handicapped.

“If government had inspected the houses and said they were “distressed” we would have packed out without complaint. They don’t care about us.”

Another resident, Ibrahim Ade, who corroborated this, said he was angry when he saw government officials sealing other buildings on Wednesday.

He said the inefficiency of government cost the two sisters their lives.

“Go to all the buildings, you will see that they are not in good condition, but government refused to do what was necessary until people died,” he said.

President of the residents’ association, Abiodun Taiwo, also berated the officials for their insensitive attitude to the state of the buildings in the estate.