Importance of natural environment, Mrs. Sato's garden. -- Geological processes and hazards are an inescapable part of life in Japan. It is not surprising, therefore, that the natural environment has deeply affected the Japanese, and is an important component of religion, literature, and art. Here natural materials are used to create a small garden which celebrates the beauty of Japan's natural environment.
Mt. Iwate, near Morioka. -- Mt. Iwate, a potentially dangerous composite volcano, reminds us that the same geological processes that can cause widespread death and destruction also produce much of the natural beauty of Japan. Convergence of earth plates bends and breaks crustal rocks producing earthquakes in the process, but at the same time uplifts the surface to create spectacular mountains. Erupting volcanoes formed along these convergent boundaries lay waste to the landscape, yet also produce magnificent, graceful peaks like Mt. Fuji and Mt. Iwate. Wave action erodes coastlines, but also creates picturesque sea cliffs and stacks and magnificent indented shorelines. The same dynamic earth processes that created the Japanese Islands make them both dangerous and magnificent. In Japan, it is very difficult not be affected, both physically and emotionally, by the natural environment.
Climatic implications, rain, Ginza, Tokyo. -- Many Japanese rivers are short and have steep gradients flowing out of mountainous terrain. This assures that runoff from storms will be rapid, and where these rivers empty onto plains flash flooding may occur. Further adding to the flood hazard is a climate that periodically causes heavy rain over short periods of time. Rainfall of eight inches or more is not uncommon during the typhoon season, especially in southwestern Japan.
High population density, Ginza, Tokyo. -- With a total area of about 143,000 square miles, Japan is a bit smaller than California. Much of the land is too mountainous for cities and towns so the population is concentrated on those areas flat enough to build upon. About 70 percent of Japanese live in cities, and in places like Tokyo the population density may reach 20,000 or more people per square mile. -- Because of its location at the boundary of converging earth plates, Japan is geologically active with frequent earthquakes and volcanic activity. When these natural processes adversely affect people they are considered geological hazards. With a large population concentrated in a small areas, Japan is susceptible to serious geological disasters.
A recently active (1970's) volcano still steaming, Mt. Komagatake, Backbone Range. -- With careful monitoring, many volcanic eruptions can be predicted and precautions taken to prevent loss of life. Prevention of damage to structures and crops, however, is not possible. Unfortunately, not all predictions are completely correct. Volcano experts and disaster prevention officials were aware of the danger of an eruption at Mt. Unzen in Kyushu in 1991, but believed the main threat would be from mudflows descending the flank of the volcano. Instead, an explosive eruption sent an avalanche of hot gas and rocks hurtling down the mountain killing 41 people in a type of eruption not previously known at Mt. Unzen.
Typical steep mountain slopes susceptible to slides and falls, between Morioka and Miyako. -- The steep mountain slopes that characterize much of Japan, combined with a climate that causes periodic heavy, saturating rainfall, provide ideal sites for landslides. Near volcanoes, thick accumulations of loose, unconsolidated ash may turn to mudflows with the first significant rainfall. In addition, there are frequent earthquakes to shake unstable slopes and act as triggers for landslides. -- Many Japanese towns are located on flat land at the foot of steep slopes and landslide disasters have been numerous. Even if slides do not directly affect settlements, they may disrupt transportation and dam rivers in narrow valleys.
Isolated mountain valleys, Kitakami Highlands, near Mt. Komagatake. -- Many valleys in Japan with enough flat land to support a village or town are separated from each other by mountainous terrain. Here two such valleys can be seen, one in the left foreground, the other in the middle distance on the right. Small settlements are present in each of these valleys. Recent road and railroad construction has improved communication, but for much of their history, many Japanese villages were relatively isolated from the rest of the country.
Accessibility of natural world in traditional Japanese building style. -- Over the centuries the constant threat of earthquakes, volcanoes, landslides, floods and tsunami in Japan have produced a culture that emphasizes co-existence with nature rather than the more typical Western approach of trying to overcome or modify the natural world. It is, therefore, not surprising that traditional Japanese buildings have sliding panels that can be opened to allow the outside world to merge with that inside the building. The boundary between inside and outside becomes less well defined and the inside becomes almost an extension of the natural environment.
Population density, urbanization, seismic risk, high-rise buildings, Shinjuku, Tokyo. -- Increased population and urbanization, combined with the scarcity and consequent high cost of land, leads to the construction of high-rise buildings in many cities. The potential danger in areas of frequent seismic activity is obvious. Modern high-rise buildings in Japan are engineered to strict earthquake codes, but the final test will be the next big quake.
Tsunami wall, Hiraiga. -- Tsunami are large waves caused by vertical displacement of sea water, usually resulting from submarine earthquakes. Destruction results when these waves wash over a shoreline. Their effects are greatest along irregular coastlines with bays that are broaden towards the ocean and narrow inland, such as the Pacific coast of Honshu. Japanese coasts have been affected by at least 72 tsunami in the last hundred years, and inundation heights up to 100 feet are not uncommon. -- Here a concrete wall has been erected in an attempt to protect the small fishing village of Hiraiga from at least small tsunami.
Coping with earthquake hazard, use of wood in structures, Morioka. -- Wooden structures are more flexible than rigid ones built of brick, adobe or concrete, and are better able to "give" and thus survive ground movement and vibration associated with earthquakes. The Japanese probably learned this through experience long ago, and along with the availability of timber in Japan, this has led to widespread use of wood for constructing even large buildings. This is not without hazard, however, because fire is a common result of damaging earthquakes.
Andesite breccia, evidence of violent volcanic eruption, Aketo. -- Rocks like this andesite breccia are abundant in Japan. The large, dark-colored, angular blocks were blasted from a volcano during a violent eruption and fell to earth where, along with ash and other volcanic debris, they became part of this rock. The size and abundance of the chunks attests to the violence of the eruption. The presence of rocks like this of different ages and in different parts of the country indicates that explosive eruptions have been widespread during Japan's geologic history.
Land use, urbanization, high population density, seismic risk, Tokyo. -- Because of its location above convergent crustal plate boundaries, Japan records about 5,000 earthquakes a year. On average, one to three earthquakes can be felt at any locality each month, and the historical frequency of major earthquake disasters in Japan is about one every ten years. Hazards associated with earthquakes include ground shaking, fire, landslides, and tsunami along the coastline. The great 1923 Tokyo earthquake left 143,000 people dead or missing, 103,000 injured, and about 250,000 homes damaged or destroyed. With a high population density, high rise buildings, increased population and commuters, the toll from the next Tokyo earthquake may be even greater.
Avalanche scar, Mt. Iwate. -- This steep slope on Mt. Iwate has several avalanche scars marked by patches of bare rock and the absence of trees. Avalanches are most common where deep snow falls on steep slopes. In Japan, moisture-laden air masses from the surrounding oceans can produce very heavy snowfall in the mountains. This, combined with frequent earthquakes which can act as triggers, mean that avalanches are another natural hazard the Japanese have to contend with.
Volcanic presence, Mt. Fuji. -- Mt. Fuji is the largest, best known, and perhaps most beautiful of Japan's volcanoes, and like many of the others it is potentially dangerous. Primary hazards include explosive eruptions, pyroclastic flows of ash and burning gas capable of traveling at speeds up to seventy miles an hour, and lava flows. In the long run, however, secondary effects of eruptions may be even more devastating. Among these are crop and structural damage from the fall of volcanic ash, mudflows and landslides in thick piles of unstable ash, flooding caused by the damming of rivers by volcanic debris and lava flows, and even climatic change resulting from suspension of ash and dust in the atmosphere.
Urban population density, seismic risk, Pontocho Street, Kyoto. -- Earthquake hazards include not only initial ground shaking, but also fire from broken pipelines, downed electrical wires, damaged heating systems, etc. In crowded Japanese cities with narrow streets and many old wooden buildings, such as this, fire can spread rapidly, and with broken water pipes and debris-filled streets blocking emergency vehicles, timely fire-fighting and rescue operations may be difficult or impossible.
Volcanic risk, Morioka and nearby Mt. Iwate. -- About 60 Japanese volcanoes (approximately ten percent of the world's total) have been active since the seventh century, and Morioka, like many Japanese cities, is susceptible to volcanic hazards. Mt. Iwate, seen here just north of Morioka, is a composite volcano, hence its eruptions are apt to be explosive. Ash fall, ash flows accompanied by burning gases, and lava flows are all possible should Mt. Iwate erupt. Increasing the danger is the fact that newer suburbs of Morioka are expanding on the flat lands toward the base of the volcano.
Horyuji Gate (AD 607), Nara, survivor of many earthquakes. -- This very old structure is persuasive evidence of the durability of wooden buildings during earthquakes. In its nearly 1,400 year history, it has survived countless earthquakes, emerging relatively unscathed because of the flex inherent in wooden structures.
Typical small, steep gradient stream, flood risk, Oirase valley. -- Small rivers, such as this, are particularly apt to flood during periods of heavy rain. The mountainous terrain and steep gradient, indicated by rapids and small waterfalls, assure that runoff will be rapid and the stream will rise quickly. Flooding is most likely in the early summer rainy period when stagnant weather fronts can produce 16 to 23 inches of rain in a 48 hour period, and during the fall typhoon season. Flooding can also occur as a result of rapid spring snow melt. Along with earthquakes and volcanic activity, flooding is a major natural hazard in Japan.
Ryoanji rock garden, Kyoto. -- This famous garden invites one to contemplate the natural physical environment. Only natural materials are used, and we might ask whether this is a reconstruction of the natural world in miniature. Is it meant to increase our awareness of the environment we must live in and the natural processes we cannot control?
