Reconstruction of the main parameters of old large earthquakes in Soviet Central Asia using the paleoseismogeological method

Никонов, А. А.

doi:10.1016/0040-1951(88)90191-6

Cited by 43 publications

(33 citation statements)

References 3 publications

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“…In the Northern Pamirs the second-order faults strike northwest or northeast and join the major thrust belts obliquely. This structural complexity is seen on Landsat imagery [Institute of Geography, 1983] and verified by fieldwork [Nikonov, 1988]. Predominant strike-slip faulting for two moderate events (events 1 and 9) may represent deformation on these second-order faults (Figure 3).…”

Section: 0omentioning

confidence: 75%

Active tectonics of the Pamirs and Karakorum

Fan¹,

Ni²,

Wallace³

1994

J. Geophys. Res.

142

150

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The source parameters of moderate‐ to large‐sized earthquakes and the spatial distribution of earthquake hypocenters are used to investigate the active tectonics and three‐dimensional configuration of the subducted lithosphere in the Pamir‐Karakorum intracontinental convergence zone. The continental collision has resulted in intense deformation in the upper crust. The deformation is distributed over a broad area and is absorbed by thrust and strike‐slip faulting. Along the northern margin of the Pamirs, where the deformation due to continental collision is most intense, the Northern Pamir Thrust and several major fault zones mark the present boundary. Most of the earthquakes that occurred in these fault zones are shallow crustal events with focal mechanism solutions correlated with the tectonic features of the region. Along the Pamir Front, thrust faulting dominates, while on the western and eastern edges of the Pamirs the style of deformation is characterized by oblique thrusting with a component of strike‐slip motion. Thrust‐type events beneath the Tadjik Depression indicate that both the sedimentary rocks and the basement are involved in shortening. Right‐lateral strike‐slip motion is observed on the eastern edge of the Pamirs where they border the Tarim Basin and in the Talas‐Fergana‐Kun Lun fault zone. A southward dipping seismic zone beneath the Pamirs and Karakorum indicates that the Asian lithosphere has been subducted along the Pamir Front to a depth of at least 200 km. This interpretation is consistent with published geological and geophysical data. Focal mechanism solutions of some intermediate‐depth events beneath the Pamirs show strike‐slip faulting with approximately N‐S horizontally oriented P axes, indicating that nearly horizontal compression at the intermediate depth is the predominant mode of deformation. A 90‐km‐deep event beneath the Karakorum is interpreted as occurring in the subducted Asian lithosphere; the fact that the P axis of this event is oriented parallel to the descending plate suggests downdip compression within the Asian lithosphere. The overall tectonics of the region is interpreted as a consequence of the underthrusting Asian lithosphere being impinged upon by the shallow northward underthrusting Indian lithosphere.

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Section: 0omentioning

confidence: 75%

Active tectonics of the Pamirs and Karakorum

Fan¹,

Ni²,

Wallace³

1994

J. Geophys. Res.

142

150

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“…This might either be a sign that the thrust is locked and accumulating elastic strain, as is postulated for the Main Himalaya Thrust [ Ader et al ., ], or that it is creeping. Scarps and a series of apparently synchronal rockslides, however, indicate that the frontal thrust is capable of producing large earthquakes [ Nikonov , ; Strecker et al ., ; Arrowsmith and Strecker , ]. At right angle to the ~13–15 mm/yr approximately north‐south shortening across the Pamir thrust system, there is also a ~5 mm/yr westward motion measured with GPS [ Zubovich et al ., , Figure ] that implies dextral slip along the approximately east trend of the Pamir thrust system.…”

Section: Discussionmentioning

confidence: 99%

“…Seismicity indicates deformation of both the sedimentary rocks and the southeast dipping basement below [ Hamburger et al ., ]. One of the largest historical earthquakes in our study region, the 1949 M 7.4 Khait earthquake (Figure and b), occurred on the Vakhsh thrust system (Figure ) or on faults already in the Tian Shan [ Leith and Simpson , ; Nikonov , ; Evans et al ., ].…”

Section: Tectonic Settingmentioning

confidence: 99%

Seismotectonics of the Pamir

et al. 2014

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Based on a 2 year seismic record from a local network, we characterize the deformation of the seismogenic crust of the Pamir in the northwestern part of the India-Asia collision zone. We located more than 6000 upper crustal earthquakes in a regional 3-D velocity model. For 132 of these events, we determined source mechanisms, mostly through full waveform moment tensor inversion of locally and regionally recorded seismograms. We also produced a new and comprehensive neotectonic map of the Pamir, which we relate to the seismic deformation. Along Pamir's northern margin, where GPS measurements show significant shortening, we find thrust and dextral strike-slip faulting along west to northwest trending planes, indicating slip partitioning between northward thrusting and westward extrusion. An active, north-northeast trending, sinistral transtensional fault system dissects the Pamir's interior, connecting the lakes Karakul and Sarez, and extends by distributed faulting into the Hindu Kush of Afghanistan. East of this lineament, the Pamir moves northward en bloc, showing little seismicity and internal deformation. The western Pamir exhibits a higher amount of seismic deformation; sinistral strike-slip faulting on northeast trending or conjugate planes and normal faulting indicate east-west extension and north-south shortening. We explain this deformation pattern by the gravitational collapse of the western Pamir Plateau margin and the lateral extrusion of Pamir rocks into the Tajik-Afghan depression, where it causes thin-skinned shortening of basin sediments above an evaporitic décollement. Superposition of Pamir's bulk northward movement and collapse and westward extrusion of its western flank causes the gradual change of surface velocity orientations from north-northwest to due west observed by GPS geodesy. The distributed shear deformation of the western Pamir and the activation of the Sarez-Karakul fault system may ultimately be caused by the northeastward propagation of India's western transform margin into Asia, thereby linking deformation in the Pamir all the way to the Chaman fault in the south in Afghanistan.

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“…Many different methods have been applied to date various types of slope failures (Schoeneich, 1991; Jibson, 1996); however, in the case of single rockfall blocks it seems that only lichenometry – using the size of the largest lichens as a measure of the time span since their establishment on a rock surface exposed during failure – has proved successful (Nikonov and Shebalina, 1979; Nikonov, 1988; Bull, 1996; Bull and Brandon, 1998). Lichenometry on siliceous rocks is based on the ‘yellow Rhizocarpon ’ lichens (Bull, 1996; Bull and Brandon, 1998), which are not common on calcareous substrates owing to an intolerance for calcium.…”

Section: Sampling and Block Age Datingmentioning

confidence: 99%

Rockfalls triggered by the ad 1356 Basle Earthquake

Becker

Davenport

2003

Terra Nova

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In the Basle region of Switzerland we demonstrate that rockfall blocks can be dated accurately using the radiocarbon method. Soil beneath rockfall blocks containing organic macro‐remains was sampled at four cliff sites in the Tabular Jura south‐east of Basle. A lightweight drilling rig drills a 101‐mm‐diameter hole through rockfall blocks up to 6 m in height. A downhole sampler is used to recover soil samples from below the blocks. Eighteen radiocarbon dates on charcoal, wood, needles of conifers and organic macro‐remains from 11 blocks gave dates between 970 and 440 bp. Calibrated ages range between ad 1210 and ad 1450. These results, along with field observations and historical research, suggest that a large number of blocks toppled as rockfalls within a short time interval in the epicentral area of the ad 1356 Basle earthquake.

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Reconstruction of the main parameters of old large earthquakes in Soviet Central Asia using the paleoseismogeological method

Cited by 43 publications

References 3 publications

Active tectonics of the Pamirs and Karakorum

Active tectonics of the Pamirs and Karakorum

Seismotectonics of the Pamir

Rockfalls triggered by the ad 1356 Basle Earthquake

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