THE mines ministry recorded 1 500 micro earthquakes at Anker in the Kunene region between June and September 2018 while carrying out a seismic survey.
A micro earthquake does not cause any damages and has a magnitude of less than 3,0, while a light earthquake has a magnitude of between 4,0 – 4,9, and causes moderate damages. This was revealed by mines ministry’s deputy director of geophysics Bufelo Lushetile in the final report compiled on a seismicity survey carried out on Anker between 21 June and 30 September 2018.
The survey was carried out as a result of the community experiencing five earthquakes between March and May last year, which damaged buildings and infrastructure.
As a result of the earthquakes, which measured between 4,0 and 4,6 on the Richter scale, the government was forced to relocate the pupils, teachers and staff to the nearby settlement of Fransfontein by May.
At Fransfontein, the pupils went to school in tents, and an extra block was provided for a makeshift hostel.
In the report, Lushetile states that the survey was carried out as a joint event between the Council for Geophysics South Africa and the ministry, leading to the setting up of seismic stations at Anker to monitor the tremors.
He stated that the seismic stations were deployed between 21 June 2018 and late September 2018.
“The analysis revealed that on average, five small seismic events were recorded on a daily basis, with local magnitudes ranging from -0,9 to 3,5.
“Overall, more than 1 500 earthquakes were recorded by the temporal seismic stations in the Anker area during the three months,” Lushetile said.
According to him, most of these events were small and could not be felt by humans, but were recorded by highly sensitive instruments.
“The results show that the area is still very active. It is mostly characterized by very small earthquakes, compared to what was being recorded earlier this year. However, these events may build up to a more significant event, which can only be verified through a long-term study period,” he stated.
According to Lushetile, there is still more significant concern over the usage of dilapidated buildings at the Edward //Garoëb Primary School, and hence it is recommended that the ministry should evaluate and certify the suitability of the building infrastructure.
Although pupils could return to Anker for school, the ministry warned that new infrastructure suitable for this earthquake-prone zone should be constructed.
“The old dilapidated buildings remain a safety hazard, even for small earthquakes recorded during this study. A temporary solution such as canopy gazebo tents may be utilized if necessary because they have fewer or no safety hazards when an earthquake occurred,” Lushetile stated.
The report, also endorsed by mines ministry’s executive director Simeon Negumbo’s deputy, Gloria Simubali, said earthquakes are generally associated with faults, which are thin zones of weakness representing a break in the earth’s crust.
“Faults separate the crust into different crustal blocks, and as such, earthquakes commonly occur on faults due to a slip along the faults.
“On a local scale, the possible cause for the reactivation of these faults could not be deduced from the data collected,” the report stated.
It also warned that the findings might be biased as it was a short-term study, and suggestions were made that seismic equipment be set up for a more extended period.
“It is emphasized that earthquake activities in the Anker area are natural, and there are no interventions that can be employed to stop these events. The affected Anker community is rather encouraged to adapt and consider re-enforcing their infrastructure to suit the environment they live in,” stated Lushetile.
STRANDED
Although parents were promised that their children could return to school at Anker this year, this was not the case as the pupils, teachers and staff were once again transported to Fransfontein for this academic year.
Kunene governor Marius Sheya informed The Namibian last week that the pupils started school last Wednesday already.
Sheya, who confirmed the final report on the seismicity survey at Anker, said they had to move the children due to the recommendations made that earthquake-resistant buildings were needed.
He said although the parents were hesitant, it was mainly based on transport and administrative issues, which were now sorted out.
“We transported the children to Fransfontein, and we will transport them back for a holiday as well,” said Sheya.
The Namibian last week reported on frustrated parents whose kids were still seated at home last Tuesday while the school had already commenced on 8 January 2019.
The parents felt the governor had failed to keep his promise of making sure that their children do not have to return to Fransfontein for school during this academic year.
Parents have complained about how their children’s clothes were stolen, while some became sick from the alleged unhealthy living conditions at Fransfontein.
Source: https://www.namibian.com.na/75037/read/1-500-earthquakes-at-Anker-in-3-months
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