But other changes, besides those in a vertical direction, occasionally take place; though, owing to their recent discovery, comparatively few examples are as yet known. While the throw of the Japanese fault varied greatly in amount, and once even in direction, there was also a constant shift towards the northwest of the ground on the north-east side of the fault, the displacement at one spot being as much as 13 feet. In the fault-scarp formed in 1894 in Eastern Greece, a similar shift took place, though to what extent is unknown. There is, moreover, evidence of actual compression of the earth's crust at right angles to the fault-line. The Neo valley, traversed by the Japanese fault, was apparently narrower after the earthquake than it was before, and plots of ground were reduced from 48 to 30 feet in length--_i.e._, by nearly 40 per cent. In British Baluchistan, the formation of the fissure referred to above was accompanied both by compression perpendicular, and by shifting parallel, to the fault. The actual displacement in each direction is unknown, but the resultant was not less than 27 inches. There can be no doubt that a fault-scarp is formed in the first place with great rapidity. So abrupt, indeed, were the structural displacements in the epicentral area of the Indian earthquake, that they contributed very materially to the intensity of the shock, giving rise to the excessive velocities observed at Rambrai and elsewhere (p. 273). The growth of the scarp does not, however, always cease with the first great earthquake, though it may take place in a contrary sense, as in the elevation connected with the Conception earthquake of 1835. The principal shock, according to Darwin, was followed during the few succeeding days "by some hundred minor ones (though of no inconsiderable violence), which seemed to come from the same quarter from which the first had proceeded; whilst, on the other hand, the level of the ground was certainly not raised by them; but, on the contrary, after an interval of some weeks, it stood rather lower than it did immediately after the great convulsion."[91] AFTER-SHOCKS. A series of after-shocks, more or less long, is a constant attendant on every great tectonic earthquake, and few are the earthquakes of any degree of strength that can be regarded as completely isolated. Even in those which visit this country, after-shocks are seldom absent. For instance, confining ourselves to the last few years, the Pembroke earthquake of 1892 was followed by 8 shocks, the Inverness earthquake of 1890 by at least 10, and possibly by 19 shocks, and that of the same district in 1901 by 15 well-defined after-shocks in addition to many others recorded by one observer. Of 300 Italian earthquakes strong enough to cause some damage to buildings, Dr. Cancani finds that every one was either preceded or followed, and chiefly followed, by its own train of minor shocks.