Distribution of local earthquakes in the crust beneath central Lake Baikal

Abstract

We have located earthquake hypocenters in the area of central Lake Baikal using the Hypoellipse inversion of direct P traveltimes collected by a local seismological network of seven stations in 2001 through 2005. The location accuracy depends on the agreement between the reference velocity model and the real subsurface. Traveltime residuals have no bearing on the accuracy of depth estimates due to origin time errors. Hypocenter location with reference to a DSS-derived layered velocity model predicts that the crust is seismogenic between 10 and 22 km. The hypocenters cluster densely in belts trending in NE and SE directions along and across Lake Baikal. Earthquakes become deeper from 10 to 22 km toward the Selenga basin.

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

“…In some areas of interest to this paper other studies have used dense local seismograph networks to constrain the depth distribution of smaller events (e.g. Deverchere et al 1991; Avetisov 1993; Roecker et al 1993; Kovachev et al 1994; Schulte‐Pelkum et al 2005; Monsalve et al 2006; Xu et al 2006; Suvorov & Tubanov 2008) and these are discussed in each region, as appropriate.…”

“…To the west, in the Lake Baikal Rift, Radziminovitch et al (2005) and Suvorov & Tubanov (2008) found that the maximum hypocentral depths were at 25 km in south and central Lake Baikal. Suvorov & Tubanov (2008) also noted that only very rare unrepresentative events exceeded 22 km in depth. These values are shallower than that found by all local studies in the NE Rift, though still somewhat deeper than the earthquakes in Lake Baikal studied teleseismically (16 km).…”

“…The rift borders the Siberian Shield, and the underlying lithospheric structure of this area, and its relation with rifting has been debated in recent papers (Emmerson et al 2006; Petit & Déverchère 2006; Petit et al 2008). Seismicity can provide important insights to these questions and there are numerous studies of earthquakes observed both locally (Vertlib 1981; Deverchere et al 1991; Déverchère et al 1993; Gileva et al 2000; Déverchère et al 2001; Melnikova et al 2007; Suvorov & Tubanov 2008) and teleseismically (Huang & Chen 1986; Bayasgalan & Jackson 2002; Bayasgalan et al 2005a; Doser 1991a,b; Delouis et al 2002; Brazier & Nyblade 2003; Emmerson et al 2006). In particular, the reported presence of lower crustal seismicity in many of these studies may provide insights into the variation in rheology along the rift zone.…”

“…By contrast, Gileva et al (2000) and Déverchère et al (2001) studied events across the entire rift system and concluded that generally the seismogenic thickness was 35–40 km and was as much as 37 km in central Lake Baikal. Those studies, however, used a sparse regional network, and both Suvorov & Tubanov (2008) and Radziminovich (2010) suggest that the simple one layer velocity model assumed by Gileva et al (2000) and Déverchère et al (2001) in Lake Baikal leads to significantly greater depths than a more realistic layered velocity model constrained by deep seismic sounding (Suvorov et al 2002), which was used by Suvorov & Tubanov (2008).…”

Spatial Variations of Seismic Wave Attenuation in the South Baikal Basin and Adjacent Areas (Baikal Rift)

“…Также при анализе сейсмичности отмечается наличие брешей в эпицентральном поле, чередование участков повышенной и пониженной плотности эпицентров землетрясений, коррелирующих с блоковой дели-мостью земной коры [Golenetsky, 1976;Solonenko et al, 1997;Zherebtsov, 2012;Radziminovich et al, 2018]. Основная масса землетрясений в районе Южнобайкальской впадины локализуется на глубинах 9-21 км, с максимумом на 14-18 км [Arefiev et al, 2008;Radziminovich, 2010;Suvorov, Tubanov, 2008].…”