Japan Tsunami 2011 Case Study Gcse English For Free
Rare Video: Japan Tsunami
June 9, 2011—The March 11 earthquake and tsunami left more than 28,000 dead or missing. See incredible footage of the tsunami swamping cities and turning buildings into rubble.
All across northern Japan they felt it.
A violent, magnitude 9-point-zero earthquake on March 11, 2011.
It was centered about 80 miles offshore, and tsunami warnings went up immediately. In coastal cities, people knew what to do next: run to higher ground.
It’s from these vantage points on hills and in tall buildings that incredible footage was captured on video.
In Kesennuma, people retreated to a hi-rise roof top and could only watch in horror as tsunami waves inundated their city, knocking buildings into rubble and mixing into a kind of tsunami ‘soup’ filled with vehicles, building parts and contents.
Sea water cascaded over sea walls, and into cities.
This video shows the water rushing over an 18-foot seawall into Kamaishi City. The seawall here was the world’s deepest and largest, but not enough for the magnitude of the March 11 disaster.
It was the largest quake ever known in Japan, and one of the 5 largest recorded in the world.
More than 28-thousand people are confirmed dead or missing.
When two tectonic plates push together under the sea, the resulting earthquake sends an enormous burst of energy up through the ocean, displacing enormous quantities of water.
With the upward motion, a series of waves expands in all directions. In deep water, these waves travel fast – up to 500 miles an hour – but only reach a height of a few feet. A passing ship might not even notice.
But as the waves enter shallow waters, friction with the ocean floor lowers the waves’ speed but raises their height.
This video is from a Japan Coast Guard ship, confronting a tsunami wave in shallow water on March 11th.
And a rare view from the air: video of a tsunami wave approaching the shoreline.
In Japan, some tsunami waves reached as far as three miles inland.
Japan may be the most seismologically studied country in the world, and with more than 1200 high precision GPS stations, a geophysicist at the University of Alaska used the GPS data to create a visualization of the March 11 quake. The waves of displacement that you see were moving as fast as 5 miles per second
In this photo, the ripples of tsunami waves are seen moving upstream in the Naka River at Hitachinaka City.
New technology left an enormous amount of visual evidence for study in years to come, and can perhaps help us better understand the power of earthquakes and tsunamis and prevent loss of life in the future.
"2011 Miyagi earthquake" redirects here. For the aftershock that occurred on 7 April, see April 2011 Miyagi earthquake.
An aerial view of the Sendai region with black smoke coming from the Nippon Oil refinery
|Date||11 March 2011; 7 years ago (2011-03-11)|
|Origin time||14:46:24 JST (UTC+09:00)|
|Depth||29 km (18 mi)|
|Epicenter||38°19′19″N142°22′08″E / 38.322°N 142.369°E / 38.322; 142.369Coordinates: 38°19′19″N142°22′08″E / 38.322°N 142.369°E / 38.322; 142.369|
|Areas affected||Japan (shaking, tsunami)|
Pacific Rim (tsunami)
|Total damage||$360 billion USD|
|Max. intensity||IX (Violent)|
|Peak acceleration||2.99 g|
|Peak velocity||117.41 cm/s|
|Tsunami||Up to 40.5 m (133 ft)|
in Miyako, Iwate, Tōhoku
|Foreshocks||List of foreshocks and aftershocks of the 2011 Tōhoku earthquake|
|Aftershocks||11,450 (as of 3 March 2015)|
2,546 people missing
The 2011 earthquake off the Pacific coast of Tōhoku(東北地方太平洋沖地震,Tōhoku-chihō Taiheiyō Oki Jishin) was a magnitude 9.0–9.1 (Mw) underseamegathrust earthquake off the coast of Japan that occurred at 14:46 JST (05:46 UTC) on Friday 11 March 2011, with the epicentre approximately 70 kilometres (43 mi) east of the Oshika Peninsula of Tōhoku and the hypocenter at an underwater depth of approximately 29 km (18 mi). The earthquake is often referred to in Japan as the Great East Japan Earthquake(東日本大震災,Higashi nihon daishinsai)[fn 1] and is also known as the 2011 Tōhoku earthquake, and the 3.11 earthquake. It was the most powerful earthquake ever recorded in Japan, and the fourth most powerful earthquake in the world since modern record-keeping began in 1900. The earthquake triggered powerful tsunami waves that reached heights of up to 40.5 metres (133 ft) in Miyako in Tōhoku's Iwate Prefecture, and which, in the Sendai area, traveled up to 10 km (6 mi) inland. The earthquake moved Honshu (the main island of Japan) 2.4 m (8 ft) east, shifted the Earth on its axis by estimates of between 10 cm (4 in) and 25 cm (10 in), increased earth's rotational speed by 1.8 µs per day, and generated infrasound waves detected in perturbations of the low-orbiting GOCE satellite. Initially, the earthquake caused sinking of part of Honshu's Pacific coast by up to roughly a metre, but after about three years, the coast rose back and kept on rising to exceed the original height of the coast.
The latest report from the Japanese National Police Agency report confirms 15,894 deaths, 6,156 injured, and 2,546 people missing across twenty prefectures, and a report from 2015 indicated 228,863 people were still living away from their home in either temporary housing or due to permanent relocation. A 10 February 2014 agency report listed 127,290 buildings totally collapsed, with a further 272,788 buildings "half collapsed", and another 747,989 buildings partially damaged. The earthquake and tsunami also caused extensive and severe structural damage in north-eastern Japan, including heavy damage to roads and railways as well as fires in many areas, and a dam collapse.Japanese Prime MinisterNaoto Kan said, "In the 65 years after the end of World War II, this is the toughest and the most difficult crisis for Japan." Around 4.4 million households in northeastern Japan were left without electricity and 1.5 million without water.
The tsunami caused nuclear accidents, primarily the level 7meltdowns at three reactors in the Fukushima Daiichi Nuclear Power Plant complex, and the associated evacuation zones affecting hundreds of thousands of residents. Many electrical generators were taken down, and at least three nuclear reactors suffered explosions due to hydrogen gas that had built up within their outer containment buildings after cooling system failure resulting from the loss of electrical power. Residents within a 20 km (12 mi) radius of the Fukushima Daiichi Nuclear Power Plant and a 10 km (6.2 mi) radius of the Fukushima Daini Nuclear Power Plant were evacuated.
Early estimates placed insured losses from the earthquake alone at US$14.5 to $34.6 billion. The Bank of Japan offered ¥15 trillion (US$183 billion) to the banking system on 14 March in an effort to normalize market conditions. The World Bank's estimated economic cost was US$235 billion, making it the costliest natural disaster in history.
The 9.1-magnitude (Mw) underseamegathrust earthquake occurred on 11 March 2011 at 14:46 JST (05:46 UTC) in the north-western Pacific Ocean at a relatively shallow depth of 32 km (20 mi), with its epicenter approximately 72 km (45 mi) east of the Oshika Peninsula of Tōhoku, Japan, lasting approximately six minutes. The earthquake was initially reported as 7.9 Mw by the USGS before it was quickly upgraded to 8.8 Mw, then to 8.9 Mw, and then finally to 9.0 Mw. On 11 July 2016, the USGS further upgraded the earthquake to 9.1. Sendai was the nearest major city to the earthquake, 130 km (81 mi) from the epicenter; the earthquake occurred 373 km (232 mi) from Tokyo.
The main earthquake was preceded by a number of large foreshocks, with hundreds of aftershocks reported. One of the first major foreshocks was a 7.2 Mw event on 9 March, approximately 40 km (25 mi) from the epicenter of 11 March earthquake, with another three on the same day in excess of 6.0 Mw. Following the main earthquake on 11 March, a 7.4 Mw aftershock was reported at 15:08 JST (6:06 UTC), succeeded by a 7.9 Mw at 15:15 JST (6:16 UTC) and a 7.7 Mw at 15:26 JST (6:26 UTC). Over eight hundred aftershocks of magnitude 4.5 Mw or greater have occurred since the initial quake, including one on 26 October 2013 (local time) of magnitude 7.1 Mw. Aftershocks follow Omori's law, which states that the rate of aftershocks declines with the reciprocal of the time since the main quake. The aftershocks will thus taper off in time, but could continue for years.
This megathrust earthquake was a recurrence of the mechanism of the earlier 869 Sanriku earthquake, which has been estimated as having a magnitude of at least 8.4 Mw, which also created a large tsunami that inundated the Sendai plain. Three tsunami deposits have been identified within the Holocene sequence of the plain, all formed within the last 3,000 years, suggesting an 800 to 1,100 year recurrence interval for large tsunamigenic earthquakes. In 2001 it was reckoned that there was a high likelihood of a large tsunami hitting the Sendai plain as more than 1,100 years had then elapsed. In 2007, the probability of an earthquake with a magnitude of Mw 8.1–8.3 was estimated as 99% within the following 30 years.
This earthquake occurred where the Pacific Plate is subducting under the plate beneath northern Honshu. The Pacific plate, which moves at a rate of 8 to 9 cm (3.1 to 3.5 in) per year, dips under Honshu's underlying plate building large amounts of elastic energy. This motion pushes the upper plate down until the accumulated stress causes a seismic slip-rupture event. The break caused the sea floor to rise by several metres. A quake of this magnitude usually has a rupture length of at least 500 km (310 mi) and generally requires a long, relatively straight fault surface. Because the plate boundary and subduction zone in the area of the Honshu rupture is not very straight, it is unusual for the magnitude of its earthquake to exceed 8.5 Mw; the magnitude of this earthquake was a surprise to some seismologists. The hypocentral region of this earthquake extended from offshore Iwate Prefecture to offshore Ibaraki Prefecture. The Japanese Meteorological Agency said that the earthquake may have ruptured the fault zone from Iwate to Ibaraki with a length of 500 km (310 mi) and a width of 200 km (120 mi). Analysis showed that this earthquake consisted of a set of three events. Other major earthquakes with tsunamis struck the Sanriku Coast region in 1896 and in 1933.
The source area of this earthquake has a relatively high coupling coefficient surrounded by areas of relatively low coupling coefficients in the west, north, and south. From the averaged coupling coefficient of 0.5–0.8 in the source area and the seismic moment, it was estimated that the slip deficit of this earthquake was accumulated over a period of 260–880 years, which is consistent with the recurrence interval of such great earthquakes estimated from the tsunami deposit data. The seismic moment of this earthquake accounts for about 93% of the estimated cumulative moment from 1926 to March 2011. Hence, earthquakes with magnitudes about 7 since 1926 in this area only had released part of the accumulated energy. In the area near the trench, the coupling coefficient is high, which could act as the source of the large tsunami.
Most of the foreshocks are interplate earthquakes with thrust-type focal mechanisms. Both interplate and intraplate earthquakes appeared in the aftershocks offshore Sanriku coast with considerable proportions.
The strong ground motion registered at the maximum of 7 on the Japan Meteorological Agency seismic intensity scale in Kurihara, Miyagi Prefecture. Three other prefectures—Fukushima, Ibaraki and Tochigi—recorded an upper 6 on the JMA scale. Seismic stations in Iwate, Gunma, Saitama and Chiba Prefecture measured a lower 6, recording an upper 5 in Tokyo.
In Russia, the main shock could be felt in Yuzhno-Sakhalinsk (MSK 4) and Kurilsk (MSK 4). The aftershock at 06:25 UTC could be felt in Yuzhno-Kurilsk (MSK 5) and Kurilsk (MSK 4).
The surface energy of the seismic waves from the earthquake was calculated to be at 1.9×1017joules, which is nearly double that of the 9.1 Mw2004 Indian Ocean earthquake and tsunami that killed 230,000 people. If harnessed, the seismic energy from this earthquake would power a city the size of Los Angeles for an entire year. The seismic moment (M0), which represents a physical size for the event, was calculated by the USGS at 3.9×1022 joules, slightly less than the 2004 Indian Ocean quake.
Japan's National Research Institute for Earth Science and Disaster Prevention (NIED) calculated a peak ground acceleration of 2.99 g (29.33 m/s2).[fn 2] The largest individual recording in Japan was 2.7 g, in Miyagi Prefecture, 75 km from the epicentre; the highest reading in the Tokyo metropolitan area was 0.16 g.
Portions of northeastern Japan shifted by as much as 2.4 metres (7 ft 10 in) closer to North America, making some sections of Japan's landmass wider than before. Those areas of Japan closest to the epicenter experienced the largest shifts. A 400-kilometre (250 mi) stretch of coastline dropped vertically by 0.6 metres (2 ft 0 in), allowing the tsunami to travel farther and faster onto land. One early estimate suggested that the Pacific plate may have moved westward by up to 20 metres (66 ft), and another early estimate put the amount of slippage at as much as 40 m (130 ft). On 6 April the Japanese coast guard said that the quake shifted the seabed near the epicenter 24 metres (79 ft) and elevated the seabed off the coast of Miyagi Prefecture by 3 metres (9.8 ft). A report by the Japan Agency for Marine-Earth Science and Technology, published in Science on 2 December 2011, concluded that the seabed in the area between the epicenter and the Japan Trench moved 50 metres (160 ft) east-southeast and rose about 7 metres (23 ft) as a result of the quake. The report also stated that the quake had caused several major landslides on the seabed in the affected area.
The Earth's axis shifted by estimates of between 10 cm (4 in) and 25 cm (10 in). This deviation led to a number of small planetary changes, including the length of a day, the tilt of the Earth, and the Chandler wobble. The speed of the Earth's rotation increased, shortening the day by 1.8 microseconds due to the redistribution of Earth's mass. The axial shift was caused by the redistribution of mass on the Earth's surface, which changed the planet's moment of inertia. Because of conservation of angular momentum, such changes of inertia result in small changes to the Earth's rate of rotation. These are expected changes for an earthquake of this magnitude. The earthquake also generated infrasound waves detected by perturbations in the orbit of the GOCE satellite, which thus serendipitously became the first seismograph in orbit.
Soil liquefaction was evident in areas of reclaimed land around Tokyo, particularly in Urayasu,Chiba City, Funabashi, Narashino (all in Chiba Prefecture) and in the Koto, Edogawa, Minato, Chūō, and Ōta Wards of Tokyo. Approximately 30 homes or buildings were destroyed and 1,046 other buildings were damaged to varying degrees. Nearby Haneda Airport, built mostly on reclaimed land, was not damaged. Odaiba also experienced liquefaction, but damage was minimal.
Shinmoedake, a volcano in Kyushu, erupted three days after the earthquake. The volcano had previously erupted in January 2011; it is not known if the later eruption was linked to the earthquake. In Antarctica, the seismic waves from the earthquake were reported to have caused the Whillans Ice Stream to slip by about 0.5 metres (1 ft 8 in).
The first sign international researchers had that the earthquake caused such a dramatic change in the Earth's rotation came from the United States Geological Survey which monitors Global Positioning Satellite stations across the world. The Survey team had several GPS monitors located near the scene of the earthquake. The GPS station located nearest the epicenter moved almost 4 m (13 ft). This motivated government researchers to look into other ways the earthquake may have had large scale effects on the planet. Calculations at NASA's Jet Propulsion Laboratory determined that the Earth's rotation was changed by the earthquake to the point where the days are now 1.8 microseconds shorter.
Further information: List of foreshocks and aftershocks of the 2011 Tōhoku earthquake
Japan experienced over 1,000 aftershocks since the earthquake, with 80 registering over magnitude 6.0 Mw and several of which have been over magnitude 7.0 Mw.
A magnitude 7.4 Mw at 15:08 (JST), 7.9 Mw at 15:15 and a 7.7 Mw quake at 15:26 all occurred on 11 March.
A month later, a major aftershock struck offshore on 7 April with a magnitude of 7.1 Mw. Its epicenter was underwater, 66 km (41 mi) off the coast of Sendai. The Japan Meteorological Agency assigned a magnitude of 7.4 MJMA, while the U.S. Geological Survey lowered it to 7.1 Mw. At least four people were killed, and electricity was cut off across much of northern Japan including the loss of external power to Higashidōri Nuclear Power Plant and Rokkasho Reprocessing Plant.
Four days later on 11 April, another magnitude 7.1 Mw aftershock struck Fukushima, causing additional damage and killing a total of three people.
On 7 December 2012 a large aftershock of magnitude 7.3 Mw caused a minor tsunami, and again on 26 October 2013 small tsunami waves were recorded after a 7.1 Mw aftershock.
As of 16 March 2012 aftershocks continued, totaling 1887 events over magnitude 4.0; a regularly updated map showing all shocks of magnitude 4.5 and above near or off the east coast of Honshu in the last seven days showed over 20 events.
As of 11 March 2016[update] there had been 869 aftershocks of 5.0 Mw or greater, 118 of 6.0 Mw or greater, and 9 over 7.0 Mw as reported by the Japanese Meteorological Agency.
The number of aftershocks was associated with decreased health across Japan.
Earthquake Warning System
One minute before the earthquake was felt in Tokyo, the Earthquake Early Warning system, which includes more than 1,000 seismometers in Japan, sent out warnings of impending strong shaking to millions. It is believed that the early warning by the Japan Meteorological Agency (JMA) saved many lives. The warning for the general public was delivered about 8 seconds after the first P wave was detected, or about 31 seconds after the earthquake occurred. However, the estimated intensities were smaller than the actual ones in some places, especially in Kanto, Koshinetsu, and Northern Tōhoku regions where the populace warning did not trigger. According to the JMA Meteorological Research Institute (ja), reasons for the underestimation include a saturated magnitude scale when using maximum amplitude as input, failure to fully take into account the area of the hypocenter, and the initial amplitude of the earthquake being less than that which would be predicted by an empirical relationship.
There were also cases where large differences between estimated intensities by the Earthquake Early Warning system and the actual intensities occurred in the aftershocks and triggered earthquakes. Such discrepancies in the warning were attributed by the JMA to the system's inability to distinguish between two different earthquakes that happened at around same time, as well as to the reduced number of reporting seismometers due to power outages and connection fails. The system's software was subsequently modified to handle this kind of situation.
An upthrust of 6 to 8 metres along a 180-km-wide seabed at 60 km offshore from the east coast of Tōhoku resulted in a major tsunami that brought destruction along the Pacific coastline of Japan's northern islands. Thousands of lives were lost when entire towns were devastated. The tsunami propagated throughout the Pacific Ocean region reaching the entire Pacific coast of North and South America from Alaska to Chile. Warnings were issued and evacuations were carried out in many countries bordering the Pacific. However, although the tsunami affected many of these places, the heights of the waves were minor. Chile's Pacific coast, one of the furthest from Japan at about 17,000 km (11,000 mi) distant, was struck by waves 2 m (6.6 ft) high, compared with an estimated wave height of 38.9 metres (128 ft) at Omoe peninsula, Miyako city, Japan.
The tsunami warning issued by the Japan Meteorological Agency was the most serious on its warning scale; it was rated as a "major tsunami", being at least 3 m (9.8 ft) high. The actual height prediction varied, the greatest being for Miyagi at 6 m (20 ft) high. The tsunami inundated a total area of approximately 561 km2 (217 sq mi) in Japan.
The earthquake took place at 14:46 JST (UTC 05:46) around 67 km (42 mi) from the nearest point on Japan's coastline, and initial estimates indicated the tsunami would have taken 10 to 30 minutes to reach the areas first affected, and then areas farther north and south based on the geography of the coastline. Just over an hour after the earthquake at 15:55 JST, a tsunami was observed flooding Sendai Airport, which is located near the coast of Miyagi Prefecture, with waves sweeping away cars and planes and flooding various buildings as they traveled inland. The impact of the tsunami in and around Sendai Airport was filmed by an NHK News helicopter, showing a number of vehicles on local roads trying to escape the approaching wave and being engulfed by it. A 4-metre-high (13 ft) tsunami hit Iwate Prefecture.Wakabayashi Ward in Sendai was also particularly hard hit. At least 101 designated tsunami evacuation sites were hit by the wave.
Like the 2004 Indian Ocean earthquake and tsunami, the damage by surging water, though much more localized, was far more deadly and destructive than the actual quake. Entire towns were destroyed in tsunami-hit areas in Japan, including 9,500 missing in Minamisanriku; one thousand bodies had been recovered in the town by 14 March 2011.
Among several factors causing the high death toll from the tsunami, one was the unexpectedly large size of the water surge. The tsunami walls in several of the affected cities had been constructed to protect against tsunamis of much lower heights. Also, many people who were caught in the tsunami thought that they were located on high enough ground to be safe. According to the conclusions of a special committee on disaster prevention, which had been designated by the Japanese government, the tsunami protection policy had been intended to deal with only those tsunamis that had been scientifically proved to occur repeatedly; the committee therefore advised that in the future the policy should be changed to protect against the highest possible tsunami. Because tsunami walls had been overtopped by this tsunami, the committee also suggested that, besides constructing tsunami walls to a height that can protect against relatively frequent tsunamis, it is still necessary to teach citizens who are protected by tsunami walls how to evacuate if a largest scale tsunami should strike those places.
Large parts of Kuji and the southern section of Ōfunato including the port area were almost entirely destroyed. Also largely destroyed was Rikuzentakata, where the tsunami was three stories high. Other cities destroyed or heavily damaged by the tsunami include Kamaishi, Miyako, Ōtsuchi, and Yamada (in Iwate Prefecture), Namie, Sōma and Minamisōma (in Fukushima Prefecture) and Shichigahama, Higashimatsushima, Onagawa, Natori, Ishinomaki, and Kesennuma (in Miyagi Prefecture). The most severe effects of the tsunami were felt along a 670-kilometre-long (420 mi) stretch of coastline from Erimo, Hokkaido, in the north to Ōarai, Ibaraki, in the south, with most of the destruction in that area occurring in the hour following the earthquake. Near Ōarai, people captured images of a huge whirlpool that had been generated by the tsunami. The tsunami washed away the sole bridge to Miyatojima, Miyagi, isolating the island's 900 residents. A two-metre-high tsunami hit Chiba Prefecture about 2½ hours after the quake, causing heavy damage to cities such as Asahi.
On 13 March 2011, the Japan Meteorological Agency (JMA) published details of tsunami observations recorded around the coastline of Japan following the earthquake. These observations included tsunami maximum readings of over 3 m (9.8 ft) at the following locations and times on 11 March 2011, following the earthquake at 14:46 JST:
- 15:12 JST – off Kamaishi – 6.8 m (22 ft)
- 15:15 JST – Ōfunato – 3.2 m (10 ft) or higher
- 15:20 JST – Ishinomaki-shi Ayukawa – 3.3 m (11 ft) or higher
- 15:21 JST – Miyako – 4.0 m (13.1 ft) or higher
- 15:21 JST – Kamaishi – 4.1 m (13 ft) or higher
- 15:44 JST – Erimo-cho Shoya – 3.5 m (11 ft)
- 15:50 JST – Sōma – 7.3 m (24 ft) or higher
- 16:52 JST – Ōarai – 4.2 m (14 ft)
Many areas were also affected by waves of 1 to 3 metres (3.3 to 9.8 ft) in height, and the JMA bulletin also included the caveat that "At some parts of the coasts, tsunamis may be higher than those observed at the observation sites." The timing of the earliest recorded tsunami maximum readings ranged from 15:12 to 15:21, between 26 and 35 minutes after the earthquake had struck. The bulletin also included initial tsunami observation details, as well as more detailed maps for the coastlines affected by the tsunami waves.
JMA also reported offshore tsunami height recorded by telemetry from mooredGPS wave-height meter buoys as follows:
- offshore of central Iwate (Miyako) – 6.3 m (20 ft)
- offshore of northern Iwate (Kuji) – 6.0 m (18 ft)
- offshore of northern Miyagi (Kesennuma) – 6.0 m (18 ft)
On 25 March 2011, Port and Airport Research Institute (PARI) reported tsunami height by visiting the port sites as follows:
- Port of Hachinohe – 5–6 m (16–19 ft)
- Port of Hachinohe area – 8–9 m (26–29 ft)
- Port of Kuji – 8–9 m (26–29 ft)
- Port of Kamaishi – 7–9 m (23–30 ft)
- Port of Ōfunato – 9.5 m (31 ft)
- Run up height, port of Ōfunato area – 24 m (79 ft)
- Fishery port of Onagawa – 15 m (50 ft)
- Port of Ishinomaki – 5 m (16 ft)
- Shiogama section of Shiogama-Sendai port – 4 m (13 ft)
- Sendai section of Shiogama-Sendai port – 8 m (26 ft)
- Sendai Airport area – 12 m (39 ft)
The tsunami at Ryōri Bay (綾里湾), Ōfunato reached a height of 40.1 m (run-up elevation). Fishing equipment was scattered on the high cliff above the bay. At Tarō, Iwate, the tsunami reached a height of 37.9 m (124 ft) up the slope of a mountain some 200 m (656 ft) away from the coastline. Also, at the slope of a nearby mountain from 400 m (1,312 ft) away at Aneyoshi fishery port (姉吉漁港) of Omoe peninsula (重茂半島) in Miyako, Iwate, Tokyo University of Marine Science and Technology found estimated tsunami run up height of 38.9 m (127 ft). This height is deemed the record in Japan historically, as of reporting date, that exceeds 38.2 m (125 ft) from the 1896 Meiji-Sanriku earthquake. It was also estimated that the tsunami reached heights of up to 40.5 metres (133 ft) in Miyako in Tōhoku's Iwate Prefecture. The inundated areas closely matched those of the 869 Sanriku tsunami.
A Japanese government study found that 58% of people in coastal areas in Iwate, Miyagi, and Fukushima prefectures heeded tsunami warnings immediately after the quake and headed for higher ground. Of those who attempted to evacuate after hearing the warning, only five percent were caught in the tsunami. Of those who didn't heed the warning, 49% were hit by the water.
Delayed evacuations in response to the warnings had a number of causes. The tsunami height that had been initially predicted by the tsunami warning system was lower than the actual tsunami height; this error contributed to the delayed escape of some residents. The discrepancy arose as follows: In order to produce a quick prediction of a tsunami's height and thus to provide a timely warning, the initial earthquake and tsunami warning that was issued for the event was based on a calculation that requires only about 3 minutes. This calculation is, in turn, based on the maximum amplitude of the seismic wave. The amplitude of the seismic wave is measured using the JMA magnitude scale, which is similar to Richter magnitude scale. However, these scales "saturate" for earthquakes that are above a certain magnitude (magnitude 8 on the JMA scale); that is, in the case of very large earthquakes, the scales' values change little despite large differences in the earthquakes' energy. This resulted in an underestimation of the tsunami's height in initial reports. Problems in issuing updates also contributed to delays in evacuations. The warning system was supposed to be updated about 15 minutes after the earthquake occurred, by which time the calculation for the moment magnitude scale would normally be completed. However, the strong quake had exceeded the measurement limit of all of the teleseismometers within Japan, and thus it was impossible to calculate the moment magnitude based on data from those seismometers. Another cause of delayed evacuations was the release of the second update on the tsunami warning long after the earthquake (28 minutes, according to observations); by that time, power failures and similar circumstances reportedly prevented the update from reaching some residents. Also, observed data from tidal meters that were located off the coast were not fully reflected in the second warning. Furthermore, shortly after the earthquake, some wave meters reported a fluctuation of "20 centimeters" (about 8 inches), and this value was broadcast throughout the mass media and the warning system, which caused some residents to underestimate the danger of their situation and even delayed or suspended their evacuation.
In response to the aforementioned shortcomings in the tsunami warning system, JMA began an investigation in 2011 and updated their system in 2013. In the updated system, for a powerful earthquake that is capable of causing the JMA magnitude scale to saturate, no quantitative prediction will be released in the initial warning; instead, there will be words that describe the situation's emergency. There are plans to install new teleseismometers with the ability to measure larger earthquakes, which would allow the calculation of a quake's moment magnitude scale in a timely manner. JMA also implemented a simpler empirical method to integrate, into a tsunami warning, data from GPS tidal meters as well as from undersea water pressure meters, and there are plans to install more of these meters and to develop further technology to utilize data observed by them. To prevent under-reporting of tsunami heights, early quantitative observation data that are smaller than the expected amplitude will be overridden and the public will instead be told that the situation is under observation. About 90 seconds after an earthquake, an additional report on the possibility of a tsunami will also be included in observation reports, in order to warn people before the JMA magnitude can be calculated.
Elsewhere across the Pacific
Shortly after the earthquake, the Pacific Tsunami Warning Center (PTWC) in Hawaii issued tsunami watches and announcements for locations in the Pacific. At 07:30 UTC, PTWC issued a widespread tsunami warning covering the entire Pacific Ocean.Russia evacuated 11,000 residents from coastal areas of the Kuril Islands. The United States National Tsunami Warning Center issued a tsunami warning for the coastal areas in most of California, all of Oregon, and the western part of Alaska, and a tsunami advisory covering the Pacific coastlines of most of Alaska, and all of Washington and British Columbia, Canada. In California and Oregon, up to 2.4-metre-high (7.9 ft) tsunami surges hit some areas, damaging docks and harbors and causing over US$10 million in damage. In Curry County, Oregon $7 million in damage occurred including the destruction of 1,100 m (3,600 ft) of dockspace at the Brookings harbor; the county has received over $1 million in FEMA emergency grants. Surges of up to 1 m (3.3 ft) hit Vancouver Island in Canada prompting some evacuations, and causing boats to be banned from the waters surrounding the island for 12 hours following the wave strike, leaving many island residents in the area without means of getting to work.
In the Philippines, waves up to 0.5 m (1.6 ft) high hit the eastern seaboard of the country. Some houses along the coast in Jayapura, Indonesia were destroyed. Authorities in Wewak, East Sepik, Papua New Guinea evacuated 100 patients from the city's Boram Hospital before it was hit by the waves, causing an estimated US$4 million in damage. Hawaii estimated damage to public infrastructure alone at US$3 million, with damage to private properties, including resort hotels such as Four Seasons Resort Hualalai, estimated at tens of millions of dollars. It was reported that a 1.5-metre-high (4.9 ft) wave completely submerged Midway Atoll's reef inlets and Spit Island, killing more than 110,000 nesting seabirds at the Midway Atoll National Wildlife Refuge. Some other South Pacific countries, including Tonga and New Zealand, and U.S. territories American Samoa and Guam, experienced larger-than-normal waves, but did not report any major damage. However, in Guam some roads were closed off and people were evacuated from low-lying areas.
Along the Pacific Coast of Mexico and South America, tsunami surges were reported, but in most places caused little or no damage. Peru reported a wave of 1.5 m (5 ft) and more than 300 homes damaged. The surge in Chile was large enough to damage more than 200 houses, with waves of up to 3 m (9.8 ft). In the Galápagos Islands, 260 families received assistance following a 3-metre (9.8 ft) surge which arrived 20 hours after the earthquake, after the tsunami warning had been lifted. There was a great deal of damage to buildings on the islands and one man was injured but there were no reported fatalities.
After 2-meter high surge hitting Chile, it was reported that the reflection from those surges traveled back across the Pacific, causing 30–60 cm surge in Japan, 47–48 hours after the earthquake, according to observation from multiple tide station (ja), including Onahama, Owase, Kushimoto.
The tsunami broke icebergs off the Sulzberger Ice Shelf