Potential Damage

Japan has had a very long history of very violent natural disasters. Earthquakes, volcanoes, and tsunamis are a consistent presence on the Japanese archipelago. Due to the subduction zone, where Japan sits, there are over 1,500 earthquakes reported yearly, with parts of the country having daily tremors. 10% of the world’s active volcanoes are on this relatively small country. Tsunamis, results of the subduction zone and its earthquakes have washed Japan smooth many times in history.
The geological area that Japan sits makes it one of the most volatile and most densely populated countries. With plates fighting for lithosphere dominance, the activity above and below the sea, and the ocean constantly threatening to overcome the island, Japan is a focus point of many scientists interested in the ways of the changing world.

The Formation of Japan

By tracking the ages of the sea floor and through the direction of the spreading, geologists have been able to make depictions of how Japan could have looked during the Paleolithic ages approximately, 35,000 B.C.E.. During the formation of Japan, we can see as at first Hokkaido (the northern most "island") and Kyushu (the southern most "island") is still connected to the Asian continent.
As continental drift continues, the direction continues outward, opening the Sea of Japan into the Pacific Ocean and Kyushu breaking away from Korea. Geologists can see that this took place around 20,000 years ago during the Last Glacial Maximum. What is very interesting is the amount of erosion in the 20,000 years that this is depicting. The black outline inside of the forming body of land is where present day Japan sits. Determining where Japan's movements and placements were during the Paleolithic times and beyond, adds new knowledge to the path Japan is taking now.
Though there are no written records of the Paleolithic age, there is evidence of the earliest Japanese and how their geological surroundings shaped their lives. At the Oyaji Temple in central Honshu (the main island), is a museum of Neolithic life. Stone statues and beautiful decorated pottery date back from as early at 5000 B.C.E.. This is an example of how even after the last glacial maximum, Japan’s environment was able to house a life of luxury compared to other inhabited lands. At this point, “Scotland was only just becoming acceptable to wandering hunter gatherer tribes”

The Tectonics of Japan

Japan sits on the Eurasian plate which, like its name states, spreads across Europe and Asia. This very large plate borders the Pacific Plate and the Philippine Plate. These three plates however, are not just bordering each other, both the Philippine and Pacific plates are subducting under the Eurasian plate. This causes the numerous volcanoes littered throughout Japan and makes Japan “one of the most earthquake-prone regions of the world” (http://www.seinan-gu.ac.jp/~djohnson/natural/quakes.html). Because of this intense subduction zone, there are many faults that run across Japan causing countless other earthquakes.The speeds of both the Pacific Plates and the Philippine Plate are different even though they are heading towards the same direction. The Pacific Plate is moving under the northern half of Japan at a rate of 80 millimeters a year. The Philippine Plate is subducting at a rate of 40 millimeters per year under the south part of Japan. Even though they are both subducting under Japan, the difference in speeds is enough to make the process not as smooth as it could be. The northern Pacific Plate is also subducting under the southern Philippine plate along a chain of volcanoes called the Izu-Bonin Volcanic Arc. This arc is kept active due to the constant subduction of plates.

Earthquakes and Tremors

Japan’s disaster history is long and deadly, with over a thousand earthquakes a year and many very high magnitude, there have been hundreds of thousands of fatalities on this island. The earthquakes of Japan happen often, the tremors sometimes daily. In just one year these small earthquakes can number into the thousands. Lasting days and sometimes weeks, they follow the strikes that lay across Japan as a result of the subduction zone. Not just following these crossing lines, the tremors can spread at rates of ten kilometers a day. In 2000 and 2001 the tremors began directly after earthquakes ranging from 4.0 to 6.7 while some ceased immediately after other earthquakes ended. 18 years, from 1990 to 2008, there have been constant earthquakes with the most recent one in July of 2008, causing fatalities, landslides, hundreds of homes destroyed, and power outages to over 8 thousand homes.
Though the earthquakes and tremors, caused by the scraping of the plates as they override each other, can be terrible now, the most fatal of all earthquakes can be found in Japan’s past. With records going to at least the twelve hundreds, there have been single earthquakes that kill hundreds of thousands of people in one quake. The most devastating modern earthquake happened in 1923 in Tokyo and Yokohama. On September 1st, an 8.3 earthquake hit that destroyed hundreds of thousands of homes and buildings. Yet since it struck at noon, the danger was even more catastrophic. With homes made of paper and wood, and with the building built so close together, the chance for disaster is eminent. The time of the earthquake was the time for cooking lunch, with open flames inside the homes, there was no chance to stop what would come next. The heat from the fires was so intense a cyclone began to form. Through the wreckage of the homes and several hundred thousand dead, the cyclone of fire moved and destroyed all that was left of the town. People fled to the bodies of water but could not escape the cyclone since all the oxygen was stripped from the area around the cone of fire.
These stories are not that rare with Japan building skyward for lack of land the dangers increase. One earthquake was so violent that the plates moved several feet in one violent shudder. With the plates slipping under each other and constant new sea floor being created it is not just the earthquakes that are a fear of the Japanese.

The Volcanoes Across Japan

Japan is an arch of mountains and volcanoes. The volcanoes of Japan are much like the volcanoes of Hawaii; many clustered volcanoes make up the little islands on the east side of Japan. This long cluster forms the northeastern part of Japan, while more volcanic arcs create the southeastern parts. History of volcanic movement can be tracked through the ages of the magma, the oldest being in the southwest, the newest south east. With this, like seafloor spreading, we can see the possible movements Japan has made throughout the centuries. Like previously stated, Japan has about one-tenth of the worlds active volcanoes. This does not include the hundreds of inactive volcanoes that litter on the Japanese archipelago; 40 active to the 180 known inactive. The most famous active volcano in Japan is Mt. Fuji.

Scientists have found that around 100,000 years ago the mountain was Komitake Fuji. This volcano erupted and another mountain took its place, "Old Fuji". Approximately 10,000 years ago, "New Fuji" was formed over the top of "Old Fuji" when that volcano erupted. The eruption in the 1700 did not change the volcano like the other eruptions did but the fact that there are at least three volcano in the form of on giant volcano is amazing.
Here in the first few seconds of this movie is an example of an all too frequent happening throughout Japan.



Another example of often occurring volcanoes is the undersea volcanoes off the coast of Japan. These can be seen erupting mostly in the western Pacific. The change in the color of the water is often spotted by fishermen and it isn't too much later that the smoke can be visibly seen, generally over many miles of ocean surface. One notoriously stubborn volcano called Fukutoku Okanoba, continuously rises and falls going from visible to not over long periods of time due to the eruptions and then the erosion that follows. The recorded years of appearance are 1904, 1914, and 1986. Within two years these appearances were completely unapparent. Most impressively, in 1914, Fukutoku Okanoba raised to around 985 feet with a circumference of about 7.5 miles; this with no exception to the general 2 year erosion time.

Volatile Ocean and the Tsunamis that Follow

Great Japanese painter Katsushita Hokusai painted the Tsunami wave of Kanagawa in 1829-1833
It is not just the earthquakes above ground that cause the danger, but the ones off the coast. These deep earthquakes cause tsunamis to occur. However, not all earthquakes cause Tsunamis, the Japanese word for harbor wave. There is a reason that it is a Japanese word. Japan has been attacked by these devastating ocean attacks since recorded history. Tsunamis can be caused by the uplift of the seafloor during its spreading, but it also can be caused by underwater land slides. Japan experiences tsunamis because of earthquakes.
There was one reported tsunami in Japan with a wave that was 80 ft high. This wave killed hundreds of thousands and left Japan almost completly cleaned off. With the possibility of waved of 450 miles per hour, there is not much someone could do except know the signs and run to higher ground as quickly as possible.
With as many earthquakes as Japan has, it would be impossible for Japan to not to experience tsunamis. Japan has experienced around 195 of these and these won’t end anytime soon. With volatile plates subducting at rapid rates and constant earthquakes because of them, Japan will not be able to escape its unfortunate position in the Pacific Ocean.



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