During February 2010 the Underberg saw the development of a
On 4 December 1809 residents of Cape Town were witness to a rare powerful earthquake in the Western Cape, according to reports the 1809 Cape Town earthquake which occurred beneath what is now Milnerton, took place in the latter period of the night at around 10pm. Hardest hit was the Jan Biesjes Kraal farm house which was destroyed in the earthquake. Reports from the area also state that water was seen gushing from cracks within the ground created by the quake. It is said that many of the residents congregated in the streets directly after the quake, unsure of what was happening. Historians report that many community members at the time thought that the 1809 earthquake was in fact an explosion, though this thought would be debunked when they saw the damage in the ground. Damage was widespread around the Cape Town area with numerous houses having cracks in their structures, though there was only a single report of any structural collapse, outside of the Jan Biesjes Kraal farm.
The 1809 Cape Town earthquake was not subject to foreshocks, but aftershocks continued for several years after the main earthquake. There were a series of three aftershocks during the same month, December 1809 and then another couple of weaker aftershocks occurring in June 1811. While there were no modern instruments at the time to get an accurate reading on the magnitude of the earthquake, estimates based on the damage caused and the reports from the community members suggests that the earthquake could have been anywhere between an 5.8 and a 6.3 on the Richter scale.
It is believed that the 1809 earthquake was caused by the weight of the extra structures being built on an unstable geographical area, as Cape Town as a city was expanding. This is a theory that is supported by the fact that were loud noises reported during these earthquakes.
While many in South Africa believe that earthquakes are more common up country, the truth is that the Western Cape area remains the most active area for earthquakes that are of natural cause and not related to mining.
Many of the documentations of this earthquake were captured by local historians, Von Buchenroder was one who surveyed the damage less than a week after the event, he wrote the following:
“Near the Kraal I found rents and fissures in the ground, one of which I followed for about the extent of a mile. In some places they were more than an inch wide, and in others much less. In many places I was able to push into them, in a perpendicular direction, a switch to its full length, of three or four feet. By the people residing in the vicinity, I was informed, that they had observed these fissures on the morning of the 5th December, in some instances three and four inches wide, and that one person had been able to push the whole length of an iron rod used to fix curtains upon them, and that others had been able to do the same with whip handles of even ten feet in length.”