The 8.9 magnitude earthquake centered off the northeast coast of Japan’s main island, Honshu, has been predicted to happen for at least a decade.
The map at right (courtesy United States Geological Survey) illustrates the epicenter of the most significant earthquake to affect Japan in a century.
The pink lines indicate the boundaries where crustal plates meet. The red lines are faults, fractures in the earth’s crust.
The islands of Japan are on the eastern edge of the giant Eurasian Plate, directly across from the Filipino Plate, and the Pacific Plate. And, located not too far away to the north is the North American Plate, and to the south is the Australian Plate.
These plates move around, albeit slowly. GPS sensors have been placed on these plates that measure movement. Geologists then know direction and velocity. The one element we do not know is stress; we do not know and have no good way of measuring the pressures that build up along fault lines, and more significantly, the subduction zones that occur at the boundary of these plates.
The Eurasian Plate pushes east, the Pacific Plate pushes west, and the Filipino Plate is caught in the middle.
Needless to say, the geologic pressures at work are pretty enormous, and dangerous when they are released.
Japan has an extensive and sophisticated civil alert network to warn people of dangers and hazards. Unfortunately, these activate after the event. Geologists and others still have no good way of predicting this form of natural hazard, not in the same way has we can predict hurricanes or cyclones.
The world gets nervous when Japan shakes because Tokyo is one of the world’s great Financial Capitals, along with New York, London, Singapore, and Hong Kong. Note that three of the world’s financial centers fall in seismically active regions (Singapore, Hong Kong, and Tokyo).
Disruption in the financial markets, markets that control the movement of money, investments – essentially global trade – makes those in London, New York, and elsewhere nervous. Most financial centers have sophisticated methods for backing up and archiving financial information. Still, the disruption and the subsequent reallocation of resources takes time to implement.