Volcanic Eruptions in Japan

Chapter 1 Introduction

l. The Japanese People and Nature

The beauty of nature has been the object of people's admiration. However, nature sometimes brings disasters to people's life. The Japanese people aretraditionally good observers of nature. We make up short poems and haiku from ourimpressions of nature. Our close observation on natural phenomena, animals and plants also led us to create proverbs. The Japanese people have worshiped nature withappreciation and awe, since they believed that sacred spirits live in all the naturalcreatures. This belief developed Japanese sophisticated views and united feeling tonature. It is also conditioned by natural surroundings and geological features of Japan. Japan belongs to the temperate and high rainfall zone, which brings distinctive seasonal changes to the land. These seasonal changes enable us to see various features of nature; fresh green foliage and pretty blossoms in spring, paddy rice fields in summer, colored leaves in fall, and snow covered scenes in winter. In its course of activities, nature brings us disasters with typhoons, floods, and heavy snowfalls including volcanic eruptions and earthquakes. Japan has a long history of volcanic eruptions and earthquakes, and these natural phenomena resulted in forming the present Japanese terrain and strata. It may be safely said that volcanic eruptions and earthquakes built up the whole land of Japan. Nature brings us both benefits and damages. Its destructive power has also affected the people's view towards nature.

Here, I would like to give my study on the relationship between nature and the Japanese people, focusing on volcanic eruptions in Japan.

2. The Relationship between Japan and its Volcanoes

There are nearly 800 active volcanoes in the world at the present time, and Japan harbors 10 percent of them. Volcanic areas in Japan make up 10 percent of our land. Japan is often called a volcanic country. Why does Japan have so many volcanoes? According to the plate tectonic theory, there are ten or more tectonics plates making up the earth's surface, and each plate is shifting some centimeters a year. The theory explains that collisions of these shifting plates on boundaries or subduction zones trigger volcanic activities and earthquakes. Japanese archipelago sits in where four plates such as Eurasian Plate, Philippine Sea Plate, Pacific Plate, and North American Plate meet each other. This means that we have more volcanic eruptions and earthquakes. Volcanoes in Japan are distributed into the west Japan volcanic belt and the east Japan volcanic belt. The west one runs from Kyushu to Chugoku district, and the east one runs from Tohoku to Hokkaido district. (Figure 1)

Figure 1 The distribution of volcanoes in Japan

Records tell that our symbolic Mt. Fuji had several volcanic eruptions scattering ash over large areas as well as Mt. Asama and Mt. Usu. Japan has experienced quite a few volcanic eruptions. It can be said that our land is based on the accumulated volcanic ash. This fact shows how closely volcanoes are related to people's life in Japan in the past and in the future.
Unzen Fugen which I pick up as an example today belongs to Kyushu district which also houses well known volcanoes such as Aso, Kujyu, Sakurajima, and Kirishima. Mt. Aso has one of the largest caldera in the world. Sakurajima has been active for 40 years since its eruption in 1955. Both volcanoes are worldly known and attract a number of tourists.Volcanic eruption is a destructive aspect of nature for people who live close by volcanoesIn the next chapter I will focus my discussion on the Unzen Fugen's last eruption as an example of people living with volcanoes.
Two hundred years ago, the eruption of Fugen claimed the greatest damage in our volcanic disaster history. In 1991 its activity again brought large damage to the same area where people are now striving for restoration of their hometowns.

Chapter 2 The Eruption of Unzen Fugen

In southern part of Shimabara City, the worst damaged area is Fukae Town. The main industries of Shimabara City are tourism, agriculture, and dairy farming. The city occupies 58.75 square kilometers ( 22.68 square miles ) of the eastern part of the Shimabara Peninsula, with population of nearly 41,000. Fukae Town occupies the southside part of the ShimabaraCity, with population of 8,000 and 23.58 and Fugen square kilometers ( 9.1 square miles )in area.
It has developed as a Shimabara City's bedtown, depending heavily on agriculture for its living.
Shimabara Peninsula faces Kumamoto Prefecture across Ariake Sea. Ferry boats run regularly to carry tourists and workers between Shimabara and Kumamoto.

Figure 2 Japan and the location of Fugen

Figure 3 The location of Nagasaki Prefecture

2. The History of Fugen's Eruptions

Records show that Fugen had the history of about 4 eruptions since 1657. These include the two explosive eruptions which caused heavy damages to the area. One of them is called the Kansei unusual happening of the year 1792. Another is the last one in 1991. The Kansei eruption came after frequent tremors which started in the previous November. The eruption on May 21, 1792 collapsed Mayuyama. Rocks and debris rushed into Ariake Sea causing tsunamis(tidal waves) along the coastal areas of both Shimabara and Kumamoto. The disaster killed 15,000 people and destroyed 3,300 homes. Death rate doubled in Shimabara area. This eruption affected Kumamoto area, about 20 kilometers ( 12.5 miles ) away from Shimabara across Ariake Sea. The event was called gShimabara taihen Higo meiwaku". ( Higo was an old name for Kumamoto ). This mesns that the event happened in Shimabara and it involved Kumamoto. The upheaval has also been remembered to be among the greatest in human loss in the history of Japanese volcanic disasters.
The collapes of Mayuyama changed the area's landscape considerably. Its 876 meter ( 2,874 feet ) peak shifted down by 150 meters ( 490 feet ). Shorelines forwarded 800 meter ( 2,600 feet ) off from the coast. Three small islands disappeared and several new smaller islands appeared. The volume of rocks and debris by the collapes reached nearly 340 million cubic meters ( 440 million cubic yards ). The damage was enlarged by a tsunami caused indirectly by he collapes. Debris flows by Mayuyama's collapes triggered a twenty-meter-high ( 65 feet ) tsunami in Ariake Sea. It occurred in the following sequence. Volcanic massive tremors began, Fugen started to erupt, underground water and thermal water increased with rising temperature, and more earthquakes shook Mayuyama. Then Mayuyama collapsed, causing a tsunsmi.
Volcanic earthquakes and activities continued for quite a while after the disaster. It took some years for the mountain to subside. Since then Unzen volcanoes have been active, causing several earthquakes and damages. The area is now remarkabiy known for frequent earthquakes in Japan.

3. The 1991 Eruption of Fugen and its Damage

Fugen started its eruption again on November 17, 1990, after the 1792 explosive eruption. It reawakened after 198 years of sleep. In 1991 activities intensified and in May a lava dome of 50 meter ( 160 feet ) across was formed in its crater. This lava dome grew and multiplied. Now 13 lava domes are recognized. The domes in whole measure 1,250 meters ( 4,100 feet ) east-west, and 600meters ( 2,000 feet ) north-south. It measures 0.6 square kilometers ( 6.5 million square feet ) in area, 333 meters ( 1,093 feet ) long, and 100 million cubic meters ( 130 million cubic yards ) in volume.
The forming of the domes brought another type of trouble; gpyroclastic flows" and gmud flows". A pyroclastic flow is a mixed flow of thermal rocks and gas expelled by an eruption. The velocity of a flow sometimes reaches more than 100 kmph ( 60 mph ). High temperature of this flow often causes fires in its paths. This is one of the most dangerous behavior of a volcanic eruption. A mud flow is a flow of accumulated volcanic ash washed down by rain in a great volume. It has a destructive power of 50 kilometer (30 mph ) speed, strong enough to sweep down big rocks and trees, causing serious damages.
Since May 1991, Fugen's pyroclastic flows and mud flows were visible. At 4:00pm on June 3, upper Mizunashi River on the east flank, a big pyroclastic flow started to flow down at 100 kmph ( 60 mph ) speed from the crater emitting gray smoke. It traveled five kilometers away. On the way down it engulfed two villages and set homes and forest afire. The flow killed some patrolling staff and newsmen, including French volcanologists Maurice and Katia Krafft and an American volcanologist Harry Glicken who were at their scientific study of the eruption. The catastorophe included 43 casualties, and 179 destroyed homes.(Figure 4)
Since then, the collapsing of lava domes have increased damages. The pyroclastic flow on
September 15 reached 300 million cubic meters ( 390 million cubic yards ) in volume, the largest
as a single collapes. It destroyed 218 structures including a school building.This flow is still active
though it has not reached the scale of causing damage. So far 41 persons were killed, 3 are missing,
and 835 homes were destroyed by the flow.
The heavy rain ( 72mm per hour=2.8 inches per hour ) on June 30 triggered a mud flow of 380,000 cubic meters ( 500,000 cubic yards ) in volume, the largest as a single one. It engulfed 148 homes and poured into Ariake Sea. It was the worst timing. The rainy season was already in with typhoons hitting the area. Since then every seasonal rain would trigger mud flows, causing some damages in the area. Mud flows destroyed area's infrastructures and transportation system, leaving the area isolated for a while. It also destroyed farmland and did severe damage to area's economy.
The damages caused by the Fugen's eruption from 1990 to March 1995 are shown below.

Chapter 3 The Restoration from the Disaster

1. The Characteristics of the Fugen Eruption

The area has suffered from the disasters for more than five years. Five years duration is a really long time for people to endure a natural disaster. Those caused by earthquakes, typhoons or others are generally transitory happenings. This was the first time in our history that warning restriction was put in effect in such a densely populated area. People who lived in the area had no choice but to evacuate. All the activities were forced to halt without any guarantee for legal compensations. In the case of Hanshin Earthquake which struck urban areas of big cities, more private and nongovernmental investment for restoration can be expected.
However, in the Shimbara's case, people have to depend mainly on governmental financial aid in every field because the damaged center is a typical farming area. Since the disaster had turned a large portion of land useless, they are required to start building new towns not only homes for refugees. This means there is a demand for a large financial support for restoration. Besides physical losses, the disaster resulted in a population decrease and stagnant economy in the area.

2. Towards Restoration

It is five years since Unzen Fugen reawakened from its 198 years sleep. Though its volcanic eruption activities subsided, restoration works have just made a start. The basic policy for restoration should be not just a plan for recovering pre-eruption state but also include projects to provide a new comfortable living space for those who lost everything. Therefore, overall measures to promote every field should be planned including disaster protection, building new towns, and activating industries. Still, many problems remain ahead. Main restoration plans are as follows.

(1) Disaster Protection

Building barriers to prevent landslides should be the first thing to start with. Though the volcanic activities diminished, 170 million cubic meter ( 220 million cubic yards ) of disposal from the eruption rests on the flank. There is a warning for possible mud flow damages for a long period of time in the future. To prepare for this, preventive structures ( 62 barriers to prevent landslides, 33 slit dams, 359 erosion control dams ) in three rivers ( Mizunashi, Nakao, Yue ) are under construction, including widening Mizunashi River. By the end of 1994, 10 barriers, 16 slit dams, and 27 erosion control dams were completed. In 1995 the super-erosion control dam along Yukou River was finished. In October 1995, along Mizunashi River the construction of a super-barrier began. In spite of these efforts of preparation, there are difficulties to proceed constructions because the project is situated in the restricted areas. Nevertheless people are working very hard to finish structures as soon as possible.

(2) Reconstructing Transportation System

Route 57 ( national highway ) was partly restored last year. The main local road which runs through the north of Shimabara Peninsula was restored completely 28 months after the disaster. Elevating railway tracks of Shimabara Railway ( a local railway ) has been planned and now under construction as a joint work of national and local governments.

(3) Housing Restoration

Fugen's eruption destroyed a large area of land. Now some areas are reserved for the preventive structures or dams. Therefore, besides building houses, a plan needs to be discussed in order to build totally new towns. By this time 367 lots, which are on sale now, were prepared in three subdivisions. Sale prices are set relatively reasonable to ease the financial burden of buyers. To build subdivisions or developments, public enterprises and The Fund for Unzen Disaster Restoration gave refugees aid to make home loans. There is also a plan to reclaim a part of Ariake Sea to build new towns.
Excavation of the ground level is planned for Annaka region in Shimabara City to prevent possible land slides in the future. The area was heavily damaged by mud flows. The whole 93 hectares will be elevated by 6 meters ( 20 feet ) when mounding is completed.
Shelters and temporary homes, which numbered 1,445 during the peak, are gradually being taken down, as public housing complex for permanent homes are prepared. Now that public aid for housing rent and tax payment due extension expired, people are required to work with their own efforts individually.

(4) Restoration Plan for Agriculture and Fishery

Fukaecho was one of the agricultural centers in Nagasaki Prefecture, producing 6.3 percent ( 10.6 billion yen=106 million US dollars ) of all the gross product of the whole prefecture in 1992. In 1993 after its 307 hectare farmland was destroyed, its gross product rate dropped to ( 7 billion yen=70 million US dollars ) 70 percent of that in 1992. At the time of December 31, 1994, there are 244 out of 667 farmers back in farming in the area. National and local governments are working on recovery of damaged farmland and farming facilities. Special aids are prepared for farmers who want to return to farming in the area.
For fishery, management fishery is suggested and promoted.

(5) Restoration Plan for Commercial Business and Tourism

Naturally business transactions in Shimabara City became very inactive in 1994. The number of shops staying in business dropped by 21.6 percent from that of 1988. Sales were 4.3 percent less than in 1988. Thus stagnant economy reduced the shop numbers and total sales in 1991.(Chart 1,2) In the downtown area, closing out of business are increasing in number, leaving a large vacant space for business. Tourists are still in low numbers compared with the average before the eruption. To increase sales, various financial aids are given to local businessmen, such as interest payment, expenses for attractions, investment for redecorating shopping malls. It may take some time to make business come back.

3. Changes in Property Value in Fukaecho

The impact by the disaster on property value in the damaged areas is shown in the chart 3 on the attached sheet.
In Japan, the average property value is still declining after the so called bubble economy in 1980s collapsed. In Nagasaki Prefecture, property value was never influenced by either bubble economy rise or its aftermath decline. In Shimabara, the disaster apparently lowered property value. It sharply dropped compared with the average value of the years 1992, 1993, and 1994 in Nagasaki Prefecture.

Chart 3 Trend of annual change of rate in Publivcation of Price and Prefectual Land and Price Survey

4. Property Value of Damaged Areas

The properties of damaged areas are apparently not in their highest value use. Therefore, to calculate their value, such factors as recovery expenses, investment capital to regain its highest value use, possible loss by future disaster and others, should be taken into consideration. Value will be based on pre-disaster value considering risk rate and recovery expenses.

The compensation theory proposes that alternative property value of similar use in a neighboring area be post-damaged value. There are some factors to be considered. When a business stays in operation before and after the disaster, there must be a criteria for value already set up. Some areas may recover pre-damaged value as restoration works proceed. In this case an alternative property is likely to be less available at reasonable price. From 1988 to 1991 there were only seven transactions on residential property. After the disaster, there were no transactions made. There is a history that neighboring area was sold for public use and its purchase price was published. This pushed up alternative property price around the area higher than pre-damaged price, leading most of the transactions for alternatives to failure.

Chapter 4 Conclusion

1. The History of Living with Volcanoes in Japan

Unzen Fugen's violent volcanic eruptions caused large damages to the Shimabara area by pyroclastic flows and mud flows. A large number of residents in Fukaecho were forced to leave their homes. They must have realized a high risk of living with volcanoes. The history of Shimabara Peninsula tells that after the big collapse of Mayuyam in 1792 Shimabra people worked very hard to rebuild their towns and farmland. Now another hard work for restoration is under way as the volcanic activities lessened. For a volcano which lives some thousand years, 200 years or several years intervals could be just a brief rest. However, if people are to stay and live in the volcanic area, they should be prepared for future possible disasters. Then, what makes people stay in this dangerous area? I would like to discuss this matter from natural and human factors.

(1) Natural Factors

(a)Japan is an island nation. Japan's mountainous terrains limit living spaces for people. To find a new empty space is not easy for those who lost their homes by disasters. They feel they have no choice except to return and stay in the same place.

(b) Traditionally the Japanese have built cities in a space surrounded by mountains which were regarded as natural walls for defense.Shimabara City, built on a small plain between Ariake sea and Unzen mountains, has developed as a community surrounded by mountains. Because of the advantage for defense, people returned to live there after natural disasters repeatedly assaulted the area .

(c)The Japanese people always cherish the feeling of unification with mother nature.Volcanic eruptions expelled a large disposal (lava and ash) in neighboring areas of volcanoes. Ashfall damages vegetations, but it also helps to create fertile soil for farming. A volcanic eruption often results in forming a good natural port. Erosions smooth mountain slopes. Craters and caldera lakes offer to make up picturesque sceneries. Actually two thirds of our national parks are located in volcanic areas. Most of the resort areas in Japan have some thing to do with volcanoes.

(2) Human Factors

(a)Shimabara area is well known to Japanese for its tragic historical events, Shimabara Revolt which was triggered by the Catholic suppression in 17 century. The revolt lasted one year, resulting in some thousands of deaths, leading Edo Shogunate to close the door to foreigners for the next 200 years. People converted into Catholicism were fishermen and their families who lived along the coastal regions of Nagasaki, Goto, Shimabara, and Amakusa. Those people were generous enough to accept different cultures,and they had strong will and independency. Their positive attitude towards life, which is still alive now, encouraged them to make new starts after deadly disasters.

(b)The Japanese people are said to believe a sort of one-year reincarnation. They think that everything turns to void in the end of a year and makes rebirth all over again on new year's day. They believe reincarnation rather than eternal life.The Western idea of eternity could be symbolized by unmovable stones, while Japanese idea of rebirth could be expressed by wood. The Japanese are used to adopt their life style to their surroundings.

(c) Generally the Japanese have strong persistence in property ownership. They value much of the long-term relationship built up in the place where they were born and brought up. This makes people cling to their own place as long as possible.

Thus Japanese people have a very close relationship with volcanoes in their life.
The Japanese ancestors worshiped volcanoes, and put them into myths and folklores, harmonizing with nature in their daily life. After the Second World War ended, especially while Japanese economy was on its sharp rise, everybody tried to make business of tourism. Local governments were eager to invest in volcanic areas which offered beautiful sceneries and hot springs in order to attract more tourists. Even today these investments are still active to develop resort complexes with golf courses, tennis courts and other facilities. Since investors are so carried away with the projects for pursuing profits, they are apt to pay less attention to the natural environment. They also underestimate nature's power and influence.The last eruption of Fugen can be a good warning to those who pursue economic efficiency and profits without considering nature's power.

2. Closing

Japanese people have overcome the hardships of loss and damage by natural disasters and restore their lives. Every time a disaster occurs, people call for risk management and better preventive measures. In spite of all, no effective measures were taken so far.
There is a well known Japanese proverb, which expresses gA disaster strikes when it is out of people's mind".Another proverb indicates a Japanese view to deal with damages by disasters. gTry to turn your bad luck into good luck". This encourages people to make best efforts for restoration from disasters.
In Japan we do not have many choices to pick up a place to live, because we have very limited space for living. Then, we have to seek harmony with nature even if it causes disasters to our living.
We never imagined that mud flows and pyroclastic flows from the Fugen's eruption could cause such huge losses and damages. We should learn a lesson from this event so that we can be prepared for coming disasters and control damages as little as possible.We should also promote our understanding of nature in order to live in harmony with it.
In my closing, I would like to add that we can stop a human behavior like nuclear explosion experiments which gives serious influence all over our earth, though we cannot stop natural behaviors like volcanic eruptions.