A powerful quake hit the Gulf of Alaska in the early hours of Tuesday; a relatively shallow magnitude-6 quake struck off Indonesia’s Java in the afternoon; and the sudden eruption of Mount Kasatsu-Shirane in Japan killed one person and injured at least 11. More than half of the world’s active volcanoes above sea level encircle the Pacific Ocean, and about 90 per cent of the world’s earthquakes occur in this zone, according to the US Geological Survey.
