News and updates

RMC Paper 1 Download - Important Information

Friday, 30 March 2012

Dear SANIRE Member, we are apologizing for any problems being experienced during the download process, but we are experiencing very large download volumes. Be patient and try again. When successful downloading please check the following:

Install Paper 1 Material

o   Download the Installer file from the website
o   Double click of the Installer and allow it to install the information on your computer
o   When done, the Installer will create an Icon on your desktop that reads 'Rock Mechanics Theory', use this icon to open the document. You do not need to open any other files, but work through th...

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MOSHing towards zero harm

Monday, 19 March 2012

Rock related safety is a major issue. The Chamber of Mines' Mine Occupational Safety and Health (MOSH) initiative is helping to address it. Find out more by reading on.

In 2003, representatives of the South African Mining industry - employers, labour unions and government - set historic and significant milestones for health and safety, to be reached by 2013, en route to zero harm for all employees.

The Chamber of Mines realised that the milestones, let alone the targets, would not easily be met without significant effort on the part of mines. Therefore the Chamber of Mines Learning Hub was ...

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From maths and computers to rock engineering

Monday, 19 March 2012

Roger Johnson's enjoyment of his job is based on the people he works with; the diversity in terms of commodity, geographic location and mining method; and the challenges and opportunities to introduce new technology, better practice and improved solutions. Here, he shares some of his ideas and experiences with Rock Talk.

Roger Johnson (56) had more of an interest in sport, the outdoors, music and social activities than in academics in his time as a scholar as La Salle College on the West Rand, but that was no predictor of his future.

Today, he has a slew of degrees and other qualifications t...

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March will bring your first free downloadable paper

Monday, 19 March 2012

Comprehensive rock engineering learning material for the South African mining industry is almost complete – and you can download it for free. Read more about it.

The writing of comprehensive rock engineering material for the South African mining industry started in the first half of 2011. It should be completed by end of March this year. At the time of writing this article, Paper 1 was complete. It should be available for download, free of charge, on the Sanire website by the time you read this article. The other papers will be available for download as and when they are completed.

Why is t...

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Design of Merensky Reef crush pillars

Monday, 19 March 2012

saimmlogo2 The Bushveld platinum group metal deposits are two distinct, shallow-dipping stratiform tabular ore bodies which strike for many hundreds of kilometres. Mining is extensive, with depths ranging from close-to-surface to 2300 m. The mining method is a variation of planar open stoping. Pillars are widely employed to support the open stopes. In the deeper levels, in-stope pillars are required to fail in a stable manner soon after being cut, and the residual pillar strength is used to stabilize the hangingwall. These pillars are commonly known as crush pillars. Little work has been done in the p...

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How Tuks makes positive change a constant

Monday, 19 March 2012

The University of Pretoria's Jannie Maritz asks: Are teaching and learning really making an impact? At Tuks, he thinks they are. Read on to find out why.

The University of Pretoria's department of Mining Engineering celebrated its 50th anniversary in 2011. The first mining engineering student enrolled for the degree in 1961 and subsequently graduated in 1964.

A lot has changed on and around the campus, yet one thing has stayed the same: The quality of mining engineer graduating has improved. Every year, Tuks Mining is delivering around 30 newly developed mining engineers into the industry. ...

Mar 31 2010

Haiti devastation had a shallow start

The recent earthquake in Haiti shocked the world. Friedemann Essrich looked into what caused it, what it was like, and how the methods used to measure it compared with methods used in South African mines. Read some of his findings here.

The M=7.0 earthquake that rocked Haiti on 12 January may have caused as many as 230 000 casualties. It was associated with a transform fault, the most famous of which is probably the San Andreas fault system in California.

haiti The source was associated with the contact between the east-drifting Caribbean Plate and the west-drifting North American Plate.

Tectonic earthquakes usually take place tens to hundreds of kilometres below surface. At only 10 km deep, the initiation point of the Haiti quake was unusually shallow. The epi-centre was located 15 km south-east of Port-au-Prince, the site of major destruction of infrastructure and most of the casualties.

Unusually strong
According to the US Geological Survey (USGS), the M=7 tremor was the largest to hit the region in over 200 years. It was followed by a series of aftershocks with M<6.0 over a period of two weeks.

The earthquake frequency map of the region, calculated by the USGS, shows less than one quake at M>5 per year for most of Haiti.

This particular analysis tool, which is based on historic seismic data of the region, is also used by South African mine seismologists to distinguish between working areas of higher and lower exposure to seismicity.

A different hazard quantification tool contouring the ground acceleration value that will be exceeded with 10% probability over the next 50 years, is not in use on SA mines, although the underlying data to build such models could be generated by mine seismic networks.

Picked up all over
The Haiti quake was recorded by 312 stations, 76 of which contributed to the moment tensor solution shown on the USGS web site. It suggests two possible failure planes, of which Strike=246 and Dip=74 offer the best match with known tectonic features in the area.

Fault plane solutions are known from local mine seismic networks, at least where 3D network coverage is good and network sensitivity allows enough sensors to be triggered.

Although they are much closer to the source on average, data from mine based seismic sensors are not usually exploited to model the detailed slip distribution on the failure plane, as it was done by Caltech for the Haiti quake.

In the case of the Haiti quake, maximum permanent deformation in the failure zone reached 4 m, around ten times larger than what was observed with the largest of SA’s mine tremors.

The effect of extreme ground motion on buildings and other infrastructure in Port-aux-Prince is well illustrated by satellite photos taken before and after the January 12 earthquake (see link to wired.com below).

However, destruction of buildings near mine tremors recorded in South Africa has only been reported in few cases, such as the 1976 event in Welkom and the 2005 Stilfontein event.

Friedemann Essrich
15/02/2010

Sources:
http://news.nationalgeographic.com/news/2010/01/100113-haiti-earthquake-red-cross/
http://www.wired.com/wiredscience/2010/01/satellite-photos-of-haiti-before-and-after-the-earthquake/
http://neic.usgs.gov/neis/eq_depot/2010/eq_100112_rja6/neic_rja6_fmt.html
http://tectonics.caltech.edu/slip_history/2010_haiti/
http://www.iris.edu/hq/retm