Focal depths of earthquakes in the Baikal region: A review

Радзиминович, Н. А.

doi:10.1134/s1069351310030043

Cited by 33 publications

(20 citation statements)

References 25 publications

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“…Déverchère et al 1991) earthquakes have been reported in the upper mantle. As Emmerson et al (2006) and Radziminovich (2010) point out, studies locating earthquakes deeper than 30 km (the maximum depth of teleseismically confirmed earthquakes) all use sparse regional networks (typically >100 km station spacing), which limits the accuracy of focal depth determination (Vertlib 1981; Deverchere et al 1991; Gileva et al 2000; Déverchère et al 2001; Melnikova et al 2007). Déverchère et al (1993), using a denser local network (minimum station spacing ∼20 km) in the north Muya region (M in Fig.…”

Section: Extensionmentioning

confidence: 99%

Earthquake depth distributions in central Asia, and their relations with lithosphere thickness, shortening and extension

Sloan¹,

Jackson²,

McKenzie³

et al. 2011

Geophysical Journal International

124

138

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S U M M A R YThis paper examines the relationship between seismogenic thickness, lithosphere structure and rheology in central and northeastern Asia. We accurately determine earthquake depth distributions which reveal important rheological variations in the lower crust. These variations exert a fundamental control on the active tectonics and the morphological evolution of the continents. We consider 323 earthquakes across the Tibetan Plateau, the Tien Shan and their forelands as well as the Baikal Rift, NE Siberia and the Laptev Sea and present the source parameters of 94 of these here for the first time. These parameters have been determined through body wave inversion, the identification of depth phases or the modelling of regional waveforms. Lower crustal earthquakes are found to be restricted to the forelands in areas undergoing shortening, and to locations where rifting coincides with abrupt changes in lithosphere thickness, such as the NE Baikal Rift and W Laptev Sea. The lower crust in these areas is seismogenic at temperatures that may be as high as 600 • C, suggesting that it is anhydrous, and is likely to have great long-term strength. Lower crustal earthquakes are therefore a useful proxy indicating strong lithosphere in places that are too small in areal extent for this to be confirmed independently by estimating effective elastic thickness from gravity-topography relations. The variation in crustal rheology indicated by the distribution of lower-crustal earthquakes has many implications ranging from the support of mountain belts and the formation of steep mountain fronts, to the localization and orientation of rifting. In combination, these processes can also be responsible for the separation of the front of the thin-skinned mountain belts from their hinterlands when continents separate.

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Section: Extensionmentioning

confidence: 99%

Earthquake depth distributions in central Asia, and their relations with lithosphere thickness, shortening and extension

Sloan¹,

Jackson²,

McKenzie³

et al. 2011

Geophysical Journal International

124

138

View full text Add to dashboard Cite

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“…The BRZ is characterized by medium depths of earthquake foci, h = 10-15 km (Golenetskii, 1997). According to other estimations (Radziminovich, 2010), the depths are 12 to 37 km, averaging 21.6 km for M ≥ 4 earthquakes.…”

Section: Data Used and Ways Of Their Processingmentioning

confidence: 99%

The basic parameters of acceleration spectra for M ≥ 5 earthquakes in the Baikal Rift Zone

Drennov

Джурик

Серебренников

et al. 2015

Russian Geology and Geophysics

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We consider the acceleration spectra of S waves from M = 5-6.5 earthquakes that occurred in three regions of the Baikal Rift Zone. The main characteristics of the shape and level of the spectra are given, and the difference between the spectra in the relative positions of the focus and seismic station is shown. Average acceleration spectra have been obtained for all three regions with regard to shape and the magnitude of the earthquakes. The spectra have been transformed so that they correspond to the accelerations of M = 6.5 and M = 7.5 earthquakes. The conclusion is made that the spectra not necessarily retain their shape even with the same movements in the focus.

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“…2). Вместе с тем необходи-мо отметить, что очаги землетрясений в Провин-ции Бассейнов и Хребтов приурочены к верхней коре (глубины ~3 км [Owens, Randall, 1989]), в то время как для Байкальской рифтовой системы ос-новная масса очагов землетрясений приурочена к средней части коры (~15 км, согласно [Radziminovich, 2010]), а землетрясения Гелайской последо-вательности в целом произошли на глубинах 5-10 км [Albaric et al, 2010]. Из этого следует, что прямое сопоставление параметров затухания для трех рифтов может быть не вполне корректным, по-скольку верхняя часть коры максимально неодно-родна [Spudish, Iida, 1993;Gusev, 1995] и положение гипоцентра источника может оказывать суще-ственное влияние на результаты.…”

Section: Fig 12unclassified

Factors influencing seismic wave attenuation in the lithosphere in continental rift zones

Добрынина¹,

Sankov²,

Девершер

et al. 2017

Geodin. tektonofiz.

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Attenuation of seismic waves in the crust and the upper mantle has been studied in three global rift systems: the Baikal rift system (Eurasia), the North Tanzanian divergence zone (Africa) and the Basin and Range Province (North America). Using the records of direct and coda waves of regional earthquakes, the single scattering theory [Aki, Chouet, 1975], the hybrid model from [Zeng, 1991] and the approach described in [Wennerberg, 1993], we estimated the seismic quality factor (QC), frequency parameter (n), attenuation coefficient (δ), and total attenuation (QT). In addition, we evaluated the contributions of two components into total attenuation: intrinsic attenuation (Qi), and scattering attenuation (Qsc). Values of QC are strongly dependent on the frequency within the range of 0.2-16 Hz, as well as on the length of the coda processing window. The observed increase of QC with larger lengths of the coda processing window can be interpreted as a decrease in attenuation with increasing depth. Having compared the depth variations in the attenuation coefficient (δ) and the frequency (n) with the velocity structures of the studied regions, we conclude that seismic wave attenuation changes at the velocity boundaries in the medium. Moreover, the comparison results show that the estimated variations in the attenuation parameters with increasing depth are considerably dependent on utilized velocity models of the medium. Lateral variations in attenuation of seismic waves correlate with the geological and geophysical characteristics of the regions, and attenuation is primarily dependent on the regional seismic activity and regional heat flow. The geological inhomogeneities of the medium and the age of crust consolidation are secondary factors. Our estimations of intrinsic attenuation (Qi) and scattering attenuation (Qsc) show that in all the three studied regions, intrinsic attenuation is the major contributor to total attenuation. Our study shows that the characteristics of seismic wave attenuation in the three different rift systems are consistent with each other, and this may suggest that the lithosphere in the zones of these different rift systems has been modified to similar levels.Key words: Baikal rift system; East African rift system; North American Basin and Range Province ; attenuation of seismic waves; seismic quality factor; seismicity; coda waves; intrinsic attenuation; scattering attenuation; heat flow GEODYNAMICS & TECTONOPHYSICS P U B L I S H E D B Y T H E I N S T I T U T E O F T H E E A R T H ' S C R U S T S I B E R I A N B R A N C H O F R U S S I A N A C A D E M Y O F S C I E N C E

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Focal depths of earthquakes in the Baikal region: A review

Cited by 33 publications

References 25 publications

Earthquake depth distributions in central Asia, and their relations with lithosphere thickness, shortening and extension

Earthquake depth distributions in central Asia, and their relations with lithosphere thickness, shortening and extension

The basic parameters of acceleration spectra for M ≥ 5 earthquakes in the Baikal Rift Zone

Factors influencing seismic wave attenuation in the lithosphere in continental rift zones

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