Investigations of local geomagnetic field changes have been carried out in Middle Asia in the following regions: Tashkent, including Charvak reservoir, Fergana and Kyzyl-Kum. Since 1968, a variety of total field features have been observed there, including: (a) slow changes at separate stations, which may be explainable by compression or tension of individual earth's crustal blocks; (b) a variety of field changes with amplitudes of a few gammas and periods of 0.5-2 years; (c) variations, which may be due to different conductivity of rocks; (d) anomalous changes in the fracture zones; (e) anomalous variations in the Charvak region, connected with reservoir filling. The amplitudes of these variations are 3-5 nT/year at Fergana, 8-9 nT/year at Kyzyl-Kum, 20-25 nT/year at Tashkent regions and up to 15-25 nT/year at Charvak reservoir area. Sometimes these anomalous changes are correlated with seismic activity (for example, Tashkent 1968 earthquakes).

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We study the covariant entropy bound in the context of gravitational collapse. First, we discuss critically the heuristic arguments advanced by Bousso. Then we solve the problem through an exact model: a Tolman-Bondi dust shell collapsing into a Schwarzschild black hole. After the collapse, a new black hole with a larger mass is formed. The horizon, L, of the old black hole then terminates at the singularity. We show that the entropy crossing L does not exceed a quarter of the area of the old horizon. Therefore, the covariant entropy bound is satisfied in this process.