If ten years ago a scientist had been asked to present a paper on this subject he would have shrugged his shoulders and left this field clear to astrologers and doomsday prophets of weird religious sects. Now, ten years later such an amount of precursory evidence has accumulated that scientists in California, Russia and Japan are confident that, given the facilities for these studies, it will be possible to forecast major earthquakes, which have their epicentres on land, within the next 10 - 20 years. In fact several successful forecasts have already been made in California.