South Africa’s Latest Earthquake: What You Need to Know
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There was a significant earthquake in South Africa on Friday, September 28. It was felt as far north as Johannesburg and Pretoria, as far east as Durban and Port Elizabeth, and as far south as Kokstad, Hermanus, and Cape Town. This leads many people to ask: What is an earthquake? Are there more earthquakes in South Africa than in other places? And why did this particular earthquake occur now? We answer these questions and others below.
What is an earthquake?
Earthquakes result from an abrupt, rapid release of energy in the Earth’s crust. This energy is released due to increased pressure within the crust (or lithosphere) caused by the mounting of geological materials above it. The most common cause of this mounting pressure is the shifting of tectonic plates. A tectonic plate is a large, solid piece of the Earth’s crust that floats on the liquid, semi-solid layer below it called the mantle. These tectonic plates are constantly moving and colliding. When two or more tectonic plates collide, the edges of the plates scrape against each other, causing the crust above the plates to bulge. The lithosphere above the bulging crust thickens. The build-up of pressure beneath this thickened lithosphere, combined with the weight of the lithosphere above it, causes the pressure to build to a point when, suddenly, the pressure is released. The sudden release of pressure beneath the thickened crust causes it to break or crack. The cracks in the crust are called faults. The energy of the release is what causes an earthquake.
How common are earthquakes in South Africa?
South Africa is a seismically active region, meaning earthquakes occur relatively frequently. The Alpine Fault, which runs from the South Island of New Zealand to the southernmost tip of South Africa, is the source of most of these earthquakes. Though South Africa does experience some earthquakes, the majority of them are too small to feel. When an earthquake does occur that is large enough for people to feel it, it is usually felt in the Western Cape. The largest earthquake recorded in South Africa occurred in Fish River (West Cape) in 1939. It had a magnitude of 6.3 and damaged some buildings in George and a railway bridge in Port Elizabeth. During this earthquake, the Cape Town observatory recorded a movement of the Earth’s surface equivalent to that of a 10-kiloton nuclear explosion.
Why do earthquakes occur?
Earthquakes are caused by the movement or shifting of rock or land masses. This movement is called tectonic movement. Two types of tectonic movement cause two types of earthquakes: – Thrust Faulting Earthquakes: These occur when two plates are moving toward each other. The top plate is thrusting under the bottom plate. This is called a subduction zone. – Strike Slip Faulting Earthquakes: These are caused by two plates moving sideways past each other.
What were the latest earthquake’s magnitude and depth?
The magnitude of the latest earthquake is 4.5, which makes it a moderate earthquake. The earthquake’s depth is approximately 10 km below the surface of the Earth. In general, earthquakes with a magnitude of 4 and above are strong enough to be felt. The bigger the earthquake, the larger the area where it can be felt.
What is the damage from an earthquake like?
Earthquakes cause damage in different ways. Firstly, the shockwave of an earthquake can damage buildings, houses, and infrastructure. Secondly, the ground can shake violently enough to cause landslides. This can happen even if the earthquake is too small to be felt. Damage caused by an earthquake also depends on the type of ground the earthquake happened on. For example, if the earthquake occurs on sandy ground, it is more likely to cause liquefaction. Liquefaction is ground that acts like a liquid due to the intense shaking. This can cause significant damage, such as the land becoming too soft to stand on.
Is there a risk of a bigger earthquake following this one?
The latest earthquake is part of a series of more minor earthquakes (aftershocks) along the Cape Fold Belt, an area of intense geological activity along the south-western coast of South Africa. These more minor quakes are expected to continue for a period of time. Large earthquakes are not expected to follow this sequence of smaller ones. If a large earthquake were to occur, it would be unrelated to the smaller sequence. It would instead occur due to the movement of the African plate with respect to the Eurasian plate.
Should you be worried about living in SA because of this quake?
The latest earthquake was not very big and caused no damage. Thus, you should not be worried about it. Because of this quake, there is no reason to be worried about living in South Africa. There is a slight chance that an earthquake of a larger magnitude could occur in the area. If such an earthquake does occur, it would be expected to cause damage.
Conclusion
Earthquakes are common in South Africa. Although significant, the latest earthquake was moderate and caused no damage. You should not be worried about living in South Africa because of this quake. There is a small chance that an earthquake of a larger magnitude could occur in the area. If such an earthquake does occur, it would be expected to cause damage. If you are living in South Africa or planning to visit the country, you do not need to worry about earthquakes affecting your plans. You should, however, be aware that they can happen in any part of the country.
