The Great 2011 Tōhoku Quake was a magnitude-9 earthquake that shook the area of northeastern Japan. It not only caused a lot of wreckage on its own, but also triggered a destructive tsunami.
The effects of this earthquake were also apparent in several other parts of the world, even going to the ice sheet of Antarctica. To this day, the debris of the resulting tsunami is still washing up on beaches in North America. Below are just a few factors we can talk about to understand the extent of this earthquake:
The Extent of the Destruction
Japanese residents who were victims of both natural disasters are still shuddering from the results. In February 2017, there were over 150,000 people who were rendered homeless. Around 50,000 had temporary housing, but their losses are immeasurable.
Japan also lost a lot of infrastructure due to the earthquake and tsunami combined. About 726,0000 buildings were partially destroyed, while 278,000 were half-ruined, and 120,000 were completely destroyed. Financially, this damage was estimated to be around $199 billion, or 16,9 trillion yen. The economic cost might go up to $235 million according to the World Bank. Overall, these statistics make the Great Tōhoku Quake the most expensive natural disaster so far.
The Element of Surprise
One surprising fact is that the Tōhoku Quake wasn’t the deadliest or even the largest earthquake of the century. The Banda Aceh earthquake in Sumatra had a magnitude of 9,1, and occurred a few years before the Tōhoku Quake in 2004. The numbers of deaths caused by this natural disaster was over 230,000. However, it was the two-for-one disaster in Japan that caused so much devastation in 2011.
The aftermath of the earthquake is even more surprising when we consider that Japan is one of the most earthquake-savvy countries in the world. The scientists in Japan did forecast an earthquake of a smaller magnitude, but they estimated it to be in the north of the main island Honshu. They didn’t forecast a tsunami arising among the aftereffects of the earthquake either.
Hints of the Earthquake
While the scientists were unable to provide proper warning, there were certain signs that might have predicted the earthquake beforehand. The areas where the Tōhoku Quake struck were quite similar to the area of Sundai, where a tsunami had struck in 869. Some Japanese geologists did figure out the connection and tried to warn the relevant officials.
However, these warnings were largely unheeded. For now, tsunami experts across the globe are assessing the history of tsunamis in Japan in order to predict the risks of any future earthquakes. The damage is done, though, as the human lives lost in Japan were ten times more than the ones lost in Sumatra.
Where The Earthquake Struck
The Tōhoku Quake struck a subduction zone on the offshore of Japan. In such a zone, one tectonic plate strides beneath the other and goes inside the mantle, which is the hot layer beneath the Earth’s crust. Since the plates are rough, they tend to stick together and build up energy that’s later released in the form of an earthquake.
In the east of Japan, the Pacific plates went under the Eurasian plate. The resulting tremor released stress that had built up over centuries.
After the earthquake drilling in the subduction zone showed that there was a thin layer of slipper clay inside the fault line. According to scientists, this layer might have been the reason why the two plates slid such a huge distance, about 164 feet. This resulted in the earthquake being of such high magnitude as well as the severity of the tsunami that followed.
This earthquake is believed to have started on Friday, March 11, at 2:46 p.m. It spread out from its center, which was around 45 miles east of Tohoku on the seafloor. The depth was about 15 miles under the water’s surface. From beginning to the end, the shaking reportedly lasted six minutes or thereabouts.
Tokyo residents had only about a minute after they were warned of the earthquake. Even this minute was a precious one, as they were able to take several measures before the major shaking began.
The early warning was largely thanks to the country’s earthquake warning system. High-speed trains were stopped, factory assembly lines were halted and people evacuated buildings where they could. Japanese residents also received tsunami warnings and earthquake alerts on their phones, so they were aware of which areas to avoid. Plus, the strict building codes in Japan also prevented the death rate from being any higher. Even so, the confirmed deaths are over 15,894, while there are over 2,500 people reported missing after the disaster occurred.
The Effects of the Earthquake
The tsunami was a major effect on its own terms but the Tohoku quake also has a few other strange results. First, it shifted the Earth on the axis of rotation though mass redistribution. This is like denting a spinning top. The resultant temblor also meant that day was shortened by a microsecond. There were also thousands of aftershocks the year after the disaster, with the largest of these being a 7.9-magnutude.
The earthquake jolts moved the Honshu island to the east by around eight feet. The northern Honshu coastline also dropped by a couple of feet. The pacific Plate also slid to the west by about 79 feet.
On a global level, the seismic waves also meant that the Whillans Ice Stream in Antarctica was speeded up, being jolted by 1.5 feet. The Norwegian fjords that pointed in the direction of Japan were also moved back and forth. The earthquake also gave rise to infrasound, which was a low-frequency ruble that was detected in space through the Goce satellite.
The earthquake may have lasted only a few minutes, but it gave rise to a massive tsunami within an hour after its occurrence. The waves went up to a height of 128 feet in Miyako city. They also traveled inland about six miles in Sendai. The estimated area flooded was about 217 square miles of the whole country.
The tsunami waves were powerful and large enough to destroy and overtop the tsunami sea walls that were placed at several points. The surge was so massive in part that it even toppled over three-story buildings which were being used by people as refuge. Near the Japanese town of Oarai, the tsunami resulted in a large whirlpool. Other issues, such as a cooling system failure at a nuclear power plant, were attributed to the tsunami alone.
The Great 201 Tohoku Quake and tsunami might be in the past, but their effects will still be known and felt for a long time yet. The tragedy is real for many families, but we may hope that this incident results in more research and observations for future oncoming disasters. This wouldn’t stop earthquakes and tsunamis from happening, but it can help to save many human loves as well as prevent major economic losses.