[1] The S receiver function technique was applied to the recordings from 36 broad-band stations in the Tien Shan. The results reveal a pronounced difference in the properties of the lithosphereasthenosphere of the Tien Shan and those of the neighboring platforms. Beneath the Tien Shan, an upper-mantle lid with an S velocity of about 4.5 km/s is underlain at a depth of about 90 km by a low-velocity zone, where the S velocity drops to 4.1 -4.2 km/ s. Trends of P and S travel time residuals are consistent with the presence of melt or other liquids in this zone. There is no evidence of any similar layer beneath the platforms. The crust is 55 -65 km thick beneath most of the Tien Shan and 45 km below the platforms, although it thins to about 45 km near the Naryn basin in the central Tien Shan.

[1] As shown by previous observations of shear wave splitting of the SKS phase, the fast direction of azimuthal anisotropy beneath the Tien Shan tends to be aligned with the strike of the belt. This direction implies that the anisotropy is related to the current orogenesis. Now we describe an attempt to constrain the distribution of the anisotropy with depth by combining observations of SKS and P receiver functions. The data are inverted for the parameters of anisotropy with the aid of a genetic algorithm. The results of the joint inversion suggest that the actual distribution of anisotropy with depth can be more complicated than usually thought. The deformed mantle layer can be a few hundred kilometres thick. In the most reliable models fast direction of anisotropy in the shallow mantle is significantly different from that inferred from the observations of SKS. At some stations the data require anisotropy in the crust.

No abstract

We present two objections to Redžić conclusion that in the ‘tough variant’ of Bell's thread-between-spaceships problem (the ships' acceleration is constant) the stretch of the thread remains finite. First, we show that because of the existence of the horizon for the accelerated observer Redžić drops out an essential part of the thread's history. Second, we show that there is no simple relation between the distance between the spaceship and the physical (leading to strain) stretch of the thread. We also present the correct estimate for the stretch, which shows that the stretch increases infinitely.

No abstract