INTERNATIONAL INSTITUTE OF SEISMOLOGY AND
EARTHQUAKE ENGINEERING (IISEE)REPORT OF STUDY TRIP
(Niigata & Miyagi Prefectures)
14 – 17 November 2011

Prepared by: D.Mungunsuren
S course(Mongolia)

INTRODUCTION
During this study trip we visited Nagaoka city Hall, Nagaoka Earthquake Disaster
Archive center, Ojiya General Hospital, Research Center for Prediction of Earthquakes andVolcanic Eruptions in Tohoku University, Onagawa Town, Tohoku Regional Development
Bureau, Senday city Aoba Ward (Ground Failure Area) and Sendai City Wakabayashi Ward(Costal Area). These places are located on Niigata and Tohoku (northeast) Region of Japan.
We had the opportunity to join this study trip to the Tohoku Region between 14 and 17
November in 2011, eight month after the great earthquake and tsunami. The purpose of thisstudy trip was a closer site survey of an effected region caused by huge earthquakes. We wereescorted by three supervisors Dr. T. Yokoi, Dr. T. Hara, Dr. Ishihara and one of our coordinators
Mr. Ajima.
In this paper, I write about the places and the university we visited during four days in theeast part of Japan.
NIIGATA PREFECTURE
On the first day, it was 14th of November, we visited Nagaoka city Hall and Nagaoka
Earthquake Disaster Archive Center to observe the damages which was caused by theunpredictable earthquake on October 23, 2004.
The town of Nagaoka and surrounding clan holdings became part of Kashiwazaki
Prefecture (now Niigata Prefecture) at the beginning of the Meiji period. The modern
municipality of Nagaoka was established on April 1, 1906. Nagaoka city is located in the central
part of the Niigata Prefecture, Japan. It is the second largest city in the prefecture, behind thecapital city of Niigata and surrounding Chuetsu region.
Japan’s longest river, the Shinano, flows north through the middle of Nagaoka, dividing it
into the East Riverside and West Riverside areas. Centering on this river, the city has a vast
variation in its climate between the seasons, and is based with beautiful and rich natural
surroundings. Nagaoka's summers are hot and humid, while the winters are snowy, influenced bythe monsoon.
On October 23, 2004, an earthquake with a magnitude of 6.8 occurred in Niigata Prefecture,
which is located about 200 km NNW of Tokyo. According to report issued by the Niigata
Prefecture Disaster Prevention Bureau on October 15, 2009, 68 people were killed, 4,795 people

were injured, 3,175 buildings were completely destroyed, approximately 118,000 houses weredamaged and at least 1,300 landslides occurred. After the earthquake, Nagaoka City’s
government built memorial halls and collectively referred to as the Great Chuetsu Earthquake
Memorial Corridor.
The Region affected by the earthquake is famous for very heavy snowfall. If the earthquake
would have occurred in the middle of winter, the damage could have been much larger due to thepotentially high snow loads. The snow in the region is wet and typically accumulates on roofs tomore than 2 meters in depth.
At first, Mr. Higuchi, from the Regional Development Strategy Department of Nagoaka
City’s government officer, gave us a lecture of the 2004 Mid Niigata Prefecture Great Cheutsu
Earthquake and Disaster and Recovery. Then he introduced us to reconstruction of Nagaoka Cityand implementation programs at length. After the lecture, we observed the video and image dataof the Great Chuetsu Earthquake Archive Center. In the Hall, the Chuetsu Region’s satellite map
which almost covered the entire floor attracted our attention. The staff of the center distributed
an ipad to each of us. Under their guidance we could identify the specially affected areas on thesatellite map through the ipad camera (Fig 1). When we touched and selected some areas on theipad, we can see some information such as earthquake's information including location, seismic
intensity of that area and damage of houses on the display.

Figure1. Getting information of the Chuetsu earthquake disaster area on the detailed the Chuetsu
Region’s satellite map by using ipad

After leaving the Nagaoka Earthquake Archive Center, we came to the Ojiya General
Hospital that is located in Ojiya City, the vicinity of the mainshock, which is one of damagedbuildings. Ojiya is small city in the south of Nagaoka City. The Great Chuetsu Earthquake
registering an intensity level of upper 6 on the Japanese Seismic scale was recorded in Ojiya City.

Strong ground motion records were observed from the mainshock and its aftershock at theneighboring base-isolation building, Suisen-no-ie (Welfare Nursing Care Center) (Fig 2(a)).
Suisen-no-ie, however, is located at the foot of a hill, while the Ojiya General Hospital is locatedat the edge of a hilltop. It is likely that input ground motions were different between twobuildings. Structural engineer Mr. Y. Shinozaki introduced information about the base-isolation
system of the building (Fig 2(b)). I understood that it can be against earthquake forces, I mean
this base isolation is most powerful tool of earthquake engineering pertaining to the passivestructural vibration control technologies.

(a)(b)

Figure2. (a) Overview of the Welfare Nursing Care Center (Suisen-no-ie) of the Ojiya General Hospital,(b) Base isolation system of Suisen-no-ie

YAMAKOSHI VILLAGE
On the second day, it was 15th of November, we visited Yamakoshi village in Niigata Prefecture
to observe the damages which were caused by the earthquake centered in the Chuetsu area ofNiigata Prefecture that occurred at 03:59 a.m. on March 12th 2011. Also we observed how theYamakoshi Village survived and recovered from this earthquake.
First, we visited the Yamakaoshi Branch Office and they introduced the situation of thedisaster and recovery work of Yamakoshi village.

Japan is a land where earthquakes happen frequently. A powerful earthquake with a magnitudeof 6.8 occurred 13 km beneath the Chuetsu Region Niigata Prefecture at 5:56 p.m. on Saturday,October 23, 2004. The unprecedented earthquake registering an intensity level of 7 on theJapanese Seismic scale was recorded in Kawaguchi Town and intensity level of upper 6 wasrecorded in Ojiya City, Yamakoshi Village, and Oguni
Town. An intensity level of lower 6 was also recorded
in Nagaoka City, Tokamachi City, and Tochio City.
Strong aftershock measuring a magnitude 6.0 at 6:11
p.m. and 6.5 at 6:34 p.m. occurred on the same day. A
maximum level of upper 6 on the Japanese Seismic
Scale was recorded during both aftershocks.
The region is geologically folded and consists of thrustfaults, which have been formed by compressive stressfrom the west-northwest and east-southeast.
Figure 3. Intensity map of the Chuetsu Region(The image is a photo taken at the Yamakoshi Village office.)

The Mid Niigata Prefecture earthquake caused many landslides and slope failures that
accumulated in the Chuetsu region of Niigata prefecture, particularly in the Imo River basin.
This area is known to be a zone of frequent landslides (Fig 4). Consequently, heavy damage wascaused in the entire basin including disruption of roads and inundation of residential areas nearrivers (Nakaideet al.2004). There were reports of damage to the forest on the mountain ridges,
because of the Mid-Niigata Prefecture earthquake which occurred in that mountainous area
(Sekiguci, 2006).

Figure 4. Landslide caused by the Chuetsu
earthquake in Yamakoshi Village.

In addition to earthquakes, other disasters include floods and snow damage. During heavy rain
falls, it is advisable to stay away from rivers. Snow damage is caused by heavy snowfalls. Somepeople have lost their lives due to avalanches or during snow removal operations. Then wevisited the remains of barrier lakes and landslides, the residential houses built by Governmentand some of history and very unique culture in this area.
MIYAGI PREFECTURE
On the third day, it was 16th of November, we visited Sendai 3rd joint government building,Tohoku University including Research Center for Prediction of Earthquakes and VolcanicEruptions and Onagawa Town.
Sendai is the capital of Miyagi Prefecture, and is the political and economic center ofTohoku (northeast) Region. Although Sendai is a large city, it is known throughout Japan as amodern city which is in harmony with nature. Sendai is located approximately 300 km-s north ofTokyo on the Pacific coast of Honshu (the largest of Japan’s four major islands). Sendai City andthe coast of Miyagi are the hardest hit areas of the 2011 off the Pacific coast of Tohoku
Earthquake and tsunami. The serious damage in this disaster is the theme of our study trip here.
This morning, we visited Sendai 3rd joint governmental building. This building
constructed in 1978 and used as the Tohoku meteorological observatory and the Tohoku defense
bureau are important facilities that communicate information after disaster such as large
earthquakes. These include Tsunami warnings and the aftershock information.
In 2008, the building was retrofitted and thebase isolator system was installed to enhance
its seismic resistant (Fig 6). In the basement
floor,Mr.

Kagayaintroducedtothedisplacement monitoring plate that wasinstalled to record the trace of building
movement anytime when an earthquake
struck.

Figure 6. Overview of Sendai 3rd joint Governmental building.

The instrument consists of the needle and the plate. He explained that on March 11, 2011 theplate recorded the building movement due to the mainshock of the off Pacific coast of Tohoku
Earthquake 2011 with maximum displacement 18 cm from the center point, some needles on theother places were broken during the shaking caused by the power of the shock or the highacceleration of the vertical motion.

(a)

(b)

(c)

Figure 7. The plastic plate (a), Needle (b), and the trace records of the Tohoku earthquake March 11, 2011

Then we visited Tohoku University and we were separated into 2 groups that Seismology andEarthquake Engineering groups. Our Seismology group went to the Research Center forPrediction of Earthquake and Volcanic Eruption in Tohoku University and the other group wentto Motosaka Laboratory and Damaged Building. Prof. N. Umino received our group and heintroduced for us about brief history of the Research Center for Prediction of Earthquake andVolcanic Eruption. He gave us some results about the Tsunami disaster and impact due to the2011 Tohoku earthquake and the tsunami behavior that occurred at affected areas. Then wevisited several places in this center. This center has a long history, one that stretches back to1912, when it was established for monitoring earthquakes. There were many old types ofseismometer, such as the one named the Wiechert Seismometer. Then we visited in the tunnel
under the center at depth of 45m by using elevator and there were so many kinds ofseismometers. For example, water tube tiltmeter, quartz tube strainmeter, quartz pendulum
tiltmeter and so on. Prof. Umino explained the principle of these observations.
Onagawa town
Onagawa is a town located in Oshika Dsitrict, Miyagi. Onagawa town is situated in an area
where it is most vulnerable to tsunami because of its geographical location. The Onagawa bay
and its shallow bathymetry characteristics was a big factor that made the towering height of thetsunami as high as 15 meters. The inundation was as far as 3 km away from the town. The town

had a flat surface with no sufficient embankments. Most residential areas were located few
meters away from the shoreline. For these reasons, the town was swept away by the tremendous
energy of the tsunami.
There were at least four pile-supported buildings toppled and /or carried over somedistances in Onagawa. Buildings were uprooted, floated several meters away from their original
positions. A three storey-hotel fronting the pacific was totally inundated. Cars were like papers
crumpled and thrown into small pieces with the strong impact of the tsunami. Roads weresubsided as well as the port facilities. Besides the massive destruction it brought to the town, 900
people were killed or missing in Onagawa Town. As shown in Figure 8, the hospital was locatedapproximately 14 meters high from the sea level. Based on our observation, the trees were dried
up which reveals that the tsunami reached and inundated the hospital 3 which surpassed theheight of the wall surrounding the area of the infrastructure.
Most of the buildings located near the seashore were completely destroyed and drifted by
the strong tsunami waves. Figure 6 shows one of the examples of building which was drifted by
the tsunami about 70 meters. Most of the roads in Onagawa town especially those near theseashore were no longer visible. The roads were subsided by approximately 80 cm as shown
which can no longer be used for transportation. Some of the roads were still covered withtsunami debris and covered with sea water. However, many roads were already built by thegovernment to pave for continuous repair and reconstruction of the devastated town. Display ofcolumn steel bars was overturned by the backflow of the tsunami wave.

Figure 8. Heavily damaged buildings at Onagawa city

On last day, it was 17 of November, we visited Tohoku Regional Development Bureau, Sendai
City Aoba Ward (Ground Failure Area), Wakabayashi Ward (Costal Area) and Tsunami Disaster.
We visited some coastal areas in Tohoku region, where tsunamis generated from the 2011 off thecoast of Pacific earthquake (M9.0) caused serious damages. In the devastated area by the tsunami,
cleanup work of debris was still undertaken even after 8 months from the disaster.
On the morning, we visited Tohoku Regional Development Bureau in Sendai city and Mr.
Kawashima gave us information of the 2011 Tohoku Earthquake and Tsunami as well as
Disaster and Recovery.
Then we went to Aoba Ward (Ground Failure Area) and Wakabayashi Ward (CoastalArea). A Ward is a subdivision of one of the cities of Japan that is large enough to have been
designated by government ordinance.
Aoba Ward is one of five wards of Sendai, the largest city in the Tohoku Region of Japan. In
these areas, also the damage of houses was caused by ground transformation. There were someroads having split and deformed and some walls tilted and collapsed.

Figure 9. Damage of Retaining Wall, House Movement and Tilting by Slidingand Ground Transformation

Wakabayshi Ward was the last destination of our study trip. This ward is located in Sendai in
Miyagi, Japan. The total area is 50 km2. In the aftermath of 2011 Tohoku Earthquake andTsunami, the area was severely damaged, where almost all 2,700 houses were destroyed andswept away by tsunamis. The earthquake and Tsunami caused extensive and severe structural
damage in Japan, including heavy damage to roads and railways as well as fires in many areas,
and a dam collapse.

CONCLUSION
The power of nature that cannot be underestimated and we cannot easily take it forgranted. There is always a high potential of a risk in facing the natural disaster. Thus,preparations on countermeasures of earthquake and tsunami mitigation are important and needed
to be taken into account.
During this study trip, I really witnessed the destructive damages caused by this Great
Tohoku earthquake. The buildings close to the coastline were seriously damaged by tsunami.
However, in this case of Japan, many people live nearby the coastline. So, how to protect theirlives and asset safety is a very important and urgent topic. Although great progress has made intechnology, we still have great difficulties in disaster mitigation and prevention.
When making disaster mitigation design and decision, we should depend not only on
theory which we have learned, but also on their real experiences.
Japan is one of the well prepared countries in the world to deal with a threat of tsunami.
They have good tsunami countermeasures. I am very impressed by the Japanese government anddisaster mitigation. Most of the affected areas continue to be well maintained and have their own
planning. Hopefully, the Japanese continues to prosper and stay strong in the face of this disaster.
In case of our country, the territory of Mongolia lies in the seismic active zone of Central
Asia. About 75 percent of urban areas are located in the region which might be hit byearthquakes of intensity VII and more by MSK scale. The 12 settlements are located in the highseismic active zones with the intensity 9 and more. Therefore, the 80 percent of our population
live in the seismic active region with the intensity 7 and more. In the last decade, according tothe rapid urbanization and development of Ulaanbaatar, the capital of Mongolia, the number ofresidents of urban areas increased and reached the 60 percent of total number of population. It
increases an earthquake risk level in Mongolia. So, we have to learn more and more about
disaster mitigation policy from Japanese.
References
1.
2.
3.
4.
5.

Handout from IISEE “Study trip to Niigata & Miyagi Prefectures”
Brosure of the Chuetsu Earthquake Memorial Corridor
Lecture note “Reconstruction of Nagaoka”, Regional development Strategy Department, Nagaoka
City, Niigata Prefecture, November 14, 2011
Handout from IISEE “Mid Niigata Pref. Earthquake of October 23, 2004”
Lecture note J. Goto “Seismic isolation retrofit at top column of B1-floor for government

6.
7.
8.
9.
10.

facilities”
Handout from IISEE “Study trip to Onagawa town, Sendai City”
Brosure of Research Center for Prediction of earthquakes and Volcanic EruptionLecture note Prof. N. Umino “The 11 March 2011 Mw9.0 Great Tohoku Earthquake”
http://en.wikipedia.org/wiki/Wakabayashi-ku,_Sendai
Web page japan tour