• September 20th, 2019

Geological hazard conditions facing Khomas


David Adetona

WINDHOEK - The Geological Survey Department in the Ministry of Mines and Energy has a leading position to ensure and encourage an environment that attracts and retains prevention, reduction or complete avoidance of geological hazards that has the potential to inflict greater loss of life and property in the country.

The department fulfils its purpose through a systematic process of gathering, collating, assessment and dissemination of all information related to disruptions of the earth surface that trigger landslides, sinkholes or earthquakes.  

The aim of the assessment and information dissemination is to prevent, prepare, respond or recover from any geological hazard or disaster.

The National Disaster Plan stated, “Without an effective means of communication it will be impossible to implement a well-coordinated emergency operation in Namibia.”  

Overview 
Khomas Region falls under one of the seismic zones which are prone to earthquake due to its geological setting such as the existence of faults within the regional tectonic structures. 

The faults are thin cracks in rocks resulting in movement that causes earthquakes. For instance, the Pahl fault around Windhoek is a well-known geological structure that runs in the north-south extending to

Rehoboth south, as well as to the north towards Okahandja. 
It is vital to state that smaller faults or rock cracks associated with the Pahl fault are also found in most parts of Windhoek. 

The faults are relatively common and are found in all parts of Namibia. 
Although the bulk of the faults are currently inactive, some are still active that cause small earthquakes. It is therefore essential to highlight that geological hazards are environmental conditions with short or long-term processes that start with relatively small features causing huge damage or disaster such as landslides that can affect the local or regional socio-economy to a large extent. 

Latest development
Geological Survey Department conducted a geotechnical study around Windhoek. The result of the study is for future application in land use planning, civil engineering structures and further city development. The pilot project which is “Engineering Geological Survey of Windhoek for the Division of Engineering and Environmental Geology” concentrated on mapping and presentation of the most important geological hazards in the territory of the City of Windhoek. The project focuses on fault zones and slope processes with related instabilities, as well as the mud flows after heavy rainfalls, inundation, near surface groundwater, erosion gullies and related issues. 

The project aims to compile a geological hazard, vulnerability and risk map as a basis for advice on urban land-use planning, as well as the development of a standard mapping-based risk assessment approach in Windhoek. There will be another pilot project planned for this year to complement previous studies for the deployment of a seismic network in the Khomas Region. The project aims to monitor seismicity or earthquakes and identify faults or cracks and seismically active zones in Windhoek. The project will consist of 10 seismic stations that has network and codes which will be used to monitor earthquakes in the region.

On Importance 
Geological hazards mapping and assessment are an important component of disaster risk management and mitigation to reduce the loss of lives or damage to properties caused by natural disasters. The aim of creating awareness on geological hazards is to reduce the damage caused by earthquakes, floods, droughts and cyclones through an ethic of prevention. Geological hazard mapping explains and identifies various areas that are susceptible or prone to various hazards. The awareness and information dissemination is essential to the public because this may reduce or prevent a lot of economic losses and avoid loss of lives, properties, services or infrastructure in the Khomas Region and Namibia.

Geological hazard studies reduce danger by knowing the steps or action to take during a hazard or disaster, whether flood, fire, drought, earthquakes or any other crisis that can greatly affect or have impact on the communities.  

The level of uncertainty will be reduced on the part of the region or communities when there is the purpose to educate or communication to prevent, prepare, respond or recover from any emergency situation. The Khomas Region is one of the known seismic zones in the country and creating geological hazard awareness and information to the inhabitants is crucial in order to prevent or prepare for any future disaster. 

Combining awareness, education and preparedness will reduce the disruptive impacts of a natural disaster on the communities in Khomas Region and the country. 

The mitigation measures such as adoption of zoning land-use practices and building codes are needed to prevent or reduce actual damage from hazards. It will be better to work toward avoiding infrastructural and structural development in mapped risk geological hazard zones. To be effective, mitigation requires a multidisciplinary team approach; each discipline has a role and contributions to make towards prevention, preparedness, response and mitigation of hazards in the country. 

There will be an increase in effective and efficiently implemented programs when there is communication and coordination among citizens, researchers, practitioners and policymakers to prevent, prepare, respond to or mitigate any hazard.

Challenges 
Earthquake seismology is a recent less studied career in Namibia. The lack of skilled personnel in this discipline is quite a challenge. With unsatisfactory or inadequate seismologists in the country, it will be a challenge to work at high rate to know or identify where earthquakes are likely to happen, and however it is also very difficult to predict when such disaster will happen with a lack of historical data especially on earthquake records in the country, as well as the procedure that all geological hazard decisions need to be supported by data. The challenge is that without records of data it is difficult to give any substantial advice or recommendations on geological hazards in Khomas Region or Namibia. 

The use of a probabilistic approach to seismic hazard characterisation to forecast future earthquakes has its limitations as it is dependent on historical earthquake studies, geological settings and fault characteristics which are sometimes incomplete due to lack of enough historical records.

Recommendations 
Some of the geological hazards can be minimised or prevented by appropriate engineering designs and proactive monitoring. However, the others are beyond human control and unpredictable. Many cities, towns or countries prone to earthquake now use built-in-protection, building and earthquake codes or anti-seismic technology designed to protect property and life in buildings in case of earthquakes. This kind of technology or system can be adopted in Khomas Region and the country. Any new building or renovation or adjustment of buildings must be constructed according to strict guidelines that would protect or save people from future earthquakes, landslides, sinkholes or collapse of buildings.


Staff Reporter
2019-06-27 09:18:39 2 months ago

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