Macroseismic survey of the ML5.5, 2014 Orkney earthquake

Midzi, V.; Zulu, B.S.; Manzunzu, B.; Mulabisana, T.; Pule, T.; Myendeki, S.; Gubela, W.

doi:10.1007/s10950-015-9491-2

Cited by 21 publications

(7 citation statements)

References 10 publications

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“…Mining-induced stress changes may also result in reactivation of pre-existing faults with fault-slip events occurring, sometimes including the extension of faults as they break through into the surrounding rock mass. The largest recorded mining-induced event of this nature occurred at Moab-Khotsong mine in South Africa, in 2014 [32]. We updated the maximum magnitude of fault-slip events (table 1) from the original M L 5.0 to M L 5.5 to reflect this.…”

Section: Seismic Source Characterization In Mining (A) Types Of Seismmentioning

confidence: 99%

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Complexities of underground mining seismic sources

Linzer

Hildyard

Wesseloo

2021

Phil. Trans. R. Soc. A.

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This paper presents a numerical investigation on the influence of the mining environment on seismic sources, with a focus on pillar failure mechanisms in tabular mining. We investigate the influence of the mining stope (underground excavation or void) on seismic inversions for the scalar moment, corner frequency, source radius, stress drop and moment tensor using synthetic events created within elastodynamic numerical modelling software, WAVE3D. The main objective is to determine whether the source parameters calculated from the recorded waveforms are due to a combination of the stope source and the pillar sources, rather than being related only to crushing of the pillar or shearing in the pillar footwall. The main finding is that the presence of stopes, and types of pillars, have a significant impact on the seismic moment and other source parameters. This is important since the moment is viewed as a robust parameter on which seismic magnitude is often based; however, this study indicates that moments calculated for pillar failure in a tabular stoping environments are less representative of the shearing or crushing source than originally thought. This article is part of the theme issue ‘Fracture dynamics of solid materials: from particles to the globe’.

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Section: Seismic Source Characterization In Mining (A) Types Of Seismmentioning

confidence: 99%

“… a Upper limit of range updated to the magnitude of largest recorded mining-induced shear shear-slip event [32]. …”

Section: Seismic Source Characterization In Miningmentioning

confidence: 99%

Complexities of underground mining seismic sources

Linzer

Hildyard

Wesseloo

2021

Phil. Trans. R. Soc. A.

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“…In other words the evaluation was done by identifying which of the descriptions for the various intensity degrees best fit all data collected for each analyzed location [e.g. Midzi et al 2015]. It means that the correct estimation is the one that best expresses the generality of the macroseismic observations Cecić 2002, Cecić andMusson 2004].…”

Section: Macroseismic Effects Of the Main Shock And Intensity Mapmentioning

confidence: 99%

Macroseismic intensity investigation of the November 2014, M=5.7, Vrancea (Romania) crustal earthquake

Constantin

Moldovan

Craiu

et al. 2016

Annals of Geophysics

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On November 22, 2014 at 21:14:17 local hour (19:14:17 GMT) a ML=5.7 crustal earthquake occurred in the area of Marasesti city of Vrancea county (Romania) - the epicenter was located at north latitude 45.87° and east longitude 27.16°, with a focal depth of 39 km. This earthquake is the main shock of a sequence that started with this and lasted until the end of January. During the sequence, characterized by the absence of foreshocks, a number of 75 earthquakes were recorded in 72 hours, the largest of which occurred in the same day with the main shock, at 22:30 (ML= 3.1). The crustal seismicity of Vrancea seismogenic region is characterized by moderate earthquakes with magnitudes that have not exceeded MW 5.9, this value being assigned to an earthquake that occurred in historical times on March 1, 1894 (Romplus catalogue). Immediately after the 2014 earthquake occurrence, the National Institute for Earth Physics (NIEP) sent macroseismic questionnaires in all affected areas, in order to define the macroseismic field of ground shaking. According to macroseismic questionnaires survey, the intensity of epicentral area reached VI MSK, and the seismic event was felt in all the extra-Carpathian area. This earthquake caused general panic and minor to moderate damage to the buildings in the epicentral area and the northeast part of country. The main purpose of this paper is to present the macroseismic map of the earthquake based on the MSK-64 intensity scale.

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“…Enhancement of the Council for Geoscience (CGS) National Seismograph Network with the deployment of surface strong motion meters in gold mining districts, was included in the study. This national network was enhanced with 15 strong motion meters within a radius of 25 km in the Klerksdorp district, which could record the Orkney M5.5 earthquake on 5 August 2014, and the aftershocks, Midzi et al (2015). Together with the strong motion data, 46 in-mine seismic sensors, mainly geophones, installed at depths of 2 km -3 km at distances of 3 km -8 km from the M5.5 hypocentre, allowed detailed investigation of the event (Moyer et al (2017) , Imanishi et al (2017), Mori et al (2018) and Manzunzu et al (2017), Figure 2).…”

Section: Introductionmentioning

confidence: 99%

2019 status report: Drilling into seismogenic zones of M2.0–M5.5 earthquakes in South African gold mines (DSeis project)

Ogasawara¹,

Liebenberg²,

Rickenbacher³

et al. 2019

Proceedings of the Ninth International Conference on Deep and High Stress Mining

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In 2014, a M5.5 earthquake ruptured the range of depths between 3.5 km and 7 km near Orkney, South Africa. The main and aftershocks were very well monitored in the nearfield by dense, surface, strong motion meters and a dense underground seismic network in the deep gold mines. The mechanism of this M5.5 earthquake was left-lateral strike-slip faulting, differing from typical mining-induced earthquakes with normalfaulting mechanisms on the mining horizons shallower than 3.5 km depth. To understand why such an unusual event took place, the aftershock zone was probed by full-core NQ drilling during 2017-2018, with a total length of about 1.6 km, followed by in-hole geophysical logging, core logging, core testing, and monitoring in the drilled holes. These holes also presented a rare opportunity to investigate deep life. In addition, seismogenic zones of M2-M3 earthquakes were probed on mine horizons that were also very well monitored by acoustic emission networks. This paper reviews the early results of the project.

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Macroseismic survey of the ML5.5, 2014 Orkney earthquake

Cited by 21 publications

References 10 publications

Complexities of underground mining seismic sources

Complexities of underground mining seismic sources

Macroseismic intensity investigation of the November 2014, M=5.7, Vrancea (Romania) crustal earthquake

2019 status report: Drilling into seismogenic zones of M2.0–M5.5 earthquakes in South African gold mines (DSeis project)

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