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Large landslides with seismicity
Published in Xia-Ting Feng, Rock Mechanics and Engineering, 2017
Most earthquakes in a plate tectonic regime occur at plate boundaries and crustal fault systems. They are driven by the diverse movements of the individual plates and the buildup of tectonic stress and strain along the active faults. According to the elastic rebound theory, stress and strain are released by an earthquake, i.e. by a sudden failure along the focal area. Stick-slip behavior of the material at the fault is a precondition for an earthquake otherwise stress and strain would be released by silent and more or less continuous creep with a creep rate determined by the large scale plate tectonic movements. We may also say that one or several earthquakes restore stability in the area where they occur, however the plate tectonic movement is not influenced by the stress and strain released around the focal area.
Large landslides with seismicity
Published in Xia-Ting Feng, Rock Mechanics and Engineering, 2017
Most earthquakes in a plate tectonic regime occur at plate boundaries and crustal fault systems. They are driven by the diverse movements of the individual plates and the buildup of tectonic stress and strain along the active faults. According to the elastic rebound theory, stress and strain are released by an earthquake, i.e. by a sudden failure along the focal area. Stick-slip behavior of the material at the fault is a precondition for an earthquake otherwise stress and strain would be released by silent and more or less continuous creep with a creep rate determined by the large scale plate tectonic movements. We may also say that one or several earthquakes restore stability in the area where they occur, however the plate tectonic movement is not influenced by the stress and strain released around the focal area.
Seismicity pattern of African regions from 1964–2022: b-value and energy mapping approach
Published in Geomatics, Natural Hazards and Risk, 2023
Alemayehu Letamo, Kavitha B, Tezeswi TP
According to elastic rebound theory (Reid 1911), earthquakes are caused by the release of accumulated energy within fault raptures of rocks during sudden movements of tectonic plates. The distribution and mechanism of active faults, which are the source of significant seismicity, are crucial in seismicity studies. The map of active faults was recently compiled by Styron and Pagani (2020) under the project ‘The GEM Global Active Faults Database’. Figure 1 shows the mechanism of faulting for North Africa. It demonstrates that convergent northern Africa is subject to reverse faulting, and the formation of sizable thrust systems and orogenic belts (the Atlas and Betic/Rif chains) is primarily to responsible for the continent’s seismic activity. Diverging borders, however, show typical faulting (dextral and sinistral). It can be observed from Figure 2, that the East African rift system is now experiencing typical faulting in that it is a developing divergent tectonic plate boundary. Large earthquakes of various sizes have been recorded in historical and current times in the region around the triple intersection (Afar triangle). The area is dominated by normal faulting, according to the region’s surface geology and the focal mechanisms of earthquakes (e.g. Kebede and Kulhánek 1991; Ayele 2002), which is in line with current worldwide analyses of active faults by Styron and Pagani (2020).
Assessment of the Seismicity of Peshawar Region in Line with the Historical Data and Modern Building Codes (ASCE-07 & IBC-2006)
Published in Journal of Earthquake Engineering, 2021
Bilal Ahmad Shah, Muhammad Maqbool Sadiq, Shazim Ali Memon, Sardar Kashif Ur Rehman
The earth crust basically is divided into 15 major tectonic plates. Most of the seismic activities occur at the plate boundaries and the seismic activity is very much scarce within the tectonic plates, this assumption is called the elastic rebound theory which is quite helpful in explaining the formation of mountain ranges, large geological features and also the formation of faults from the relative movement of tectonic plates. The history of seismic activity in the region of Pakistan is mainly because of the collision of Indian plate with Eurasian plate since the last 30 to 40 million years [Aitchison, 2007]. The advancement of the Indian plate is reduced to half over this period of time which was previously 9 meters a century. The Indian plate is going through subduction during this period and the Eurasian plate thrusts upward resulting in the uplift of Himalayas (1 cm per year) is a growth rate of 10 km in one million years. The boundary of these plates is a convergent boundary and at the junction of these plates, the lithosphere is thickening and sinking into the mantle. Due to this collision, the lithosphere has shortened by about 2000 km resulting in mountain ranges i.e. Himalayas and Karakorum ranges, Pamir ranges, Hindukush Mountains, Kirthar ranges, Suleman Ranges, Naga hills of Assam towards the east, the Arakan Yoma mountains of Burma, and the Tien-Shan mountains of Central Asia and of this region [Norsar, 2007]. The northern region of Pakistan is mostly mountainous, it is going through uplift due to the subduction of Indian-Australian plate and it causes most of the seismic activity in this region including Peshawar.