Japan Impacts from the 2011 Tohoku Earthquake & Tsunami

Extreme Tsunami Runup

The 2011 Tohoku-Oki tsunami created extreme flood levels and significant inundation and destruction. 

Tsunami elevation runup levels varied along the coast due to offshore bathymetry (deep versus shallow), onshore topography (steep versus flat-lying), and the shape of the coastline (open versus V-shaped). The most extreme flood level occurred at Aneyoshi Bay near Miyako where the tsunami run-up elevation was 40-meters high. The V-shaped entrance to the bay and valley topography funneled the tsunami inland and upward simultaneously in aggressive fashion. The community at Aneyoshi Bay had experienced extreme tsunami flooding in 1896 and 1933 so they moved the community inland to high ground and erected a stone monument at a 50-meter elevation which read:

“To protect the lives of your children and elders, do not construct your homes below this elevation.”

[Photo #1] Photo of v-shaped entrance to Aneyoshi Bay, which helped funnel tsunami flooding to a 40-meter elevation. Note the trimline where trees were denuded by the tsunami (photo by Rick Wilson, CGS).

[Photo #2] Photo of Rick Wilson (CGS Senior Engineering Geologist) standing at a stone tsunami monument erected near the community of Aneyoshi Bay warning not to build below this level (photo credit Rick Wilson, CGS).

Tsunami Deposits

Japan has a long history of tsunamis including a “prehistoric” geologic record of tsunamis within the shallow soil layers. 

The most recent large tsunamis to occur in the region prior to the 2011 event were the 1933 Showa event and the 1896 Meiji event. These events were large but not on the same scale as the 2011 tsunami. Many communities in Japan focused their evacuation planning efforts on these historic events. However, geologic records of tsunami deposits indicated larger events like the one in 2011 occurring once every 1000 years or so. 

The geologic record is important for understanding the long-term tsunami history and overall tsunami hazard of a region.

[Photo #1] Japan, CGS, and USGS scientists review tsunami deposits in the field near Settai River Valley (photo by Rick Wilson, CGS).

[Photo #2] The photo shows several soil cores from ~1.2 miles (2 kilometers) inland from the coast within the Sendai Plain. The soil cores show other large tsunami deposits, including the AD 869 Jogan event and at least one to two older events approximately one-thousand years apart. Tsunami scientists date these prehistoric and historic records to evaluate the tsunami hazard. Cores were taken near Atago Shrine, Natori, Miyagi Prefecture (photo by Rick Wilson, CGS).

Ports

The coastal Tohoku region has several large deep-water ports. The Port of Sendai, which is one of the largest ports in northern Japan, was heavily damaged by the tsunami. 

Large vessels, containers, and cars became debris as flood waters transported them inland. Petroleum and chemical plants caught fire and spread contaminants during and after the tsunami. Despite this destruction, it was important to reopen portions of the Port of Sendai within weeks after the tsunami to provide a vital connection to supplies and resources.

[ Video ] showing damage to the Port of Sendai from the 2011 tsunami.

[Photo] showing large vessel stranded on the wharf within the Port of Sendai (photo by Rick Wilson, CGS).

Harbors with Fishing Vessels

Most communities along the Tohoku coast have harbors with dozens to hundreds of fishing vessels. 

During the Tohoku event, many crews tried to move their vessels offshore after the earthquake but prior to the arrival of the tsunami, which took 20-40 minutes to travel to the shoreline. Many vessels were lost because they became caught in the strong surges and harbor currents as the tsunamis arrived. 

The important lesson for crew members during a local tsunami event like this is to not take a vessel offshore, but rather evacuate to safety, unless the vessel is already underway or outside the port. The life of the crew is more important than saving the vessel.

[Photo #1] Photo showing lone fishing vessel to survive the 2011 tsunami in Noda harbor (photo by Rick Wilson, CGS).

[Photo #2] Photo showing tsunami evacuation site near Noda harbor where dozens of fishermen found safe ground (photo by Rick Wilson, CGS).

Vertical Evacuation Structures

Thousands of people were saved by evacuating to tall structures constructed to withstand the force and flooding from tsunamis. 

These vertical evacuation structures are typically constructed in areas where residents cannot safely evacuate to high ground before the arrival of a local tsunami.

[ Video ] Video showing dozens of people within Ishinomaki in a vertical evacuation structure as the 2011 tsunami arrives and quickly grows in size.

Tsunami Countermeasures

Due to Japan's recent history of large tsunamis (e.g., 1933, 1896), countermeasures such as breakwaters, seawalls, and even natural barriers such as forests were created to help protect communities.

These countermeasures were designed to protect against most, but not all, tsunamis. In some cases, countermeasures slowed the tsunami to help the public evacuate. However, they also provided residents with a false sense of security. Many residents went to the seawalls to watch the incoming surge only to learn too late the 2011 tsunami would overtop the man-made barriers.

The public should be educated about the limitations of tsunami countermeasures, and that evacuation to high ground outside of tsunami hazard areas is the most certain way to survive.

[Photo #1] Photo showing markers of the flood levels during the 1896 Meiji and 1933 Showa tsunami events in Taro. Flood levels were higher during the 2011 tsunami (photo by Bruce Jaffe, USGS).

[Photo #2] Photo of Taro’s seven-meter high seawall (top left) and ten-meter high seawall (foreground) which were heavily damaged and overtopped by the 2011 tsunami. Over time, many residents had believed that these structures would protect them from all tsunamis (photo by Rick Wilson, CGS).

Tragedy of Okawa Elementary School

Although many coastal communities in the Tohoku regions located schools inland out of tsunami hazard areas, schools in some communities remained in these hazard areas. 

Seventy-four children and ten teachers perished at the Okawa Elementary School in Ishinomaki during the 2011 tsunami. A hill close to the school could have provided safety but indecision and delays about what action to take led to this catastrophic loss of life. 

This tragic event was an important lesson to learn about sustaining tsunami evacuation planning and preparedness.

[Photo] Photo of the heavily damaged structures at Okawa Elementary School in Ishinomaki two years after the 2011 tsunami (photo by Rick Wilson, CGS).

Fukushima Daiichi nuclear disaster

[Photo] International Atomic Energy Agency fact-finding team leader Mike Weightman examines Reactor Unit 3 at the Fukushima Daiichi Nuclear Power Plant on 27 May 2011 to assess tsunami damage and study nuclear safety lessons that could be learned from the accident.

[Video] The Fukushima Nuclear Disaster is unimaginable in scale. 8 years later in the midst of a $27 billion decontamination effort, we explore inside the disaster zone and meet the locals to uncover the situation in Fukushima; past, present and future.

Debris and Hazardous Material

[Photo 1] An aerial view of damage to Rikuzentakata, Japan after a 9.1 magnitude earthquake and subsequent tsunami devastated the area in northern Japan.

[Photo 2] Debris piled high in Rikuzentakada, Iwate Prefecture.

Land Subsidence

In some areas of Japan's coast, sudden subsidence (lowering of the ground) occurred during the great earthquake.

The amount of subsidence following great earthquakes can vary from inches to six feet but the effect can be quite noticeable in low-lying areas that are now permanently flooded by the ocean.

[Photo] An aerial view of Minato, Japan, a week after a 9.1 magnitude earthquake and subsequent tsunami devastated the area (photo by Lance Cpl. Ethan Johnson, U.S. Marine Corps; NOAA/NCEI).

Building Damage

Buildings within the tsunami inundation areas sustained heavy damage from the strong forces of fast moving water and debris.

As expected, taller steel-framed and reinforced masonry structures performed better than wood-framed structures. Debris was significant and led to years of post-event cleanup.

[Photo #1] Tsunami debris engulfs a steel framed structure in Onagawa, Ishinomaki (photo by Shunichi Koshimura; NOAA/NCEI).

[Photo #2] The building in the foreground has floated off its foundation and has come to rest on its side; note the pipes visible at the base of the structure (photo by Shunichi Koshimura; NOAA/NCEI).

Residential Impacts

According to Japan’s National Police Agency (2011), close to a quarter million residential homes were either destroyed or heavily damaged by the tsunami.

Residents either relocated from the communities impacted by the tsunami or stayed in nearby temporary housing until the rebuilding efforts were completed in their communities. Communities encouraged people to stay to help with the rebuilding process and to maintain the workforce locally.

[Photo #1] Otsuchi, in Iwate prefecture, has been virtually flattened by the tsunami. The community here believes that it will take at least a decade to rebuild the town (photo by Japanese Red Cross; NOAA/NCEI).

[Photo #2] A single-story residential house sits damage and along next to an aid worker along the road through Kamaishi (photo by Patrick Fuller, International Federation of Red Cross).

Infrastructure Impact

The infrastructure in the Tohoku region suffered severe damage and disruptions. These included potable water, sewer, electricity, oil and gas, telecommunications, roads, and rail.

Vital road and telecommunication infrastructures also failed during the earthquake shaking in the region, reducing capabilities for inland cities to communicate with and assist coastal communities heavily impacted by the tsunami.

[Photo] in Iwate prefecture, a bridge was washed off its support and ended up partly under an adjacent bridge (photo by Japanese Red Cross; NOAA/NCEI).

Liquefaction

Soil liquefaction (where water-saturated sediment temporarily loses strength and acts as a fluid) was widespread not only in the Tohoku region but also 500 miles away in Tokyo (see video). 

Liquefaction led to damage in buildings, ports, roads, and other types of infrastructure.

[ Video ] Compilation of the ground moving in Japan caused by ground or soil liquefaction and broken water pipes after a magnitude 9.1 earthquake hit the country on March 11, 2011.

Ground Shaking

Ground shaking from the earthquake was felt throughout Japan and as far away as Taiwan, China, and Russia.

Intense ground shaking was felt throughout much of Honshu Island in Japan and caused large buildings to strongly sway in downtown Tokyo (see video).

[ Video ] Strong ground shaking from the magnitude 9.1 earthquake caused the high-rise buildings in downtown Tokyo to sway.