For Japanese seismologists, the Great East Japan Earthquake proved to be the event that sent them back to the drawing board.
For Japanese seismologists, the Great East Japan Earthquake proved to be the event that sent them back to the drawing board.
As one of the most powerful earthquakes on record, it forced researchers to rethink many of their assumptions about movements of the Earth's crust.
The magnitude-9.0 earthquake spawned massive tsunami that devastated the northern Tohoku region, claiming some 20,000 lives.
Seismology as a modern science got its start just over 130 years ago, courtesy of a British visitor to Japan during the Meiji Era (1868-1912).
Given the scale of the catastrophe last year, it begs the question: Where is seismology headed now?
"My house shook violently. Even when it died down the seismic movements had been so severe that I couldn't walk right."
This account from John Milne, a Briton living in Tokyo at the invitation of the Meiji government as a teacher of mining, was describing the Yokohama Earthquake that struck before dawn on Feb. 22, 1880. The epicenter was in Tokyo Bay.
The quake is estimated to have had an intensity of 4 or 5 on the Japanese scale of 7, yet it caused smokestacks and warehouses to collapse.
Coming from a country where earthquakes are practically unknown, Milne was totally unprepared for the Yokohama temblor.
In light of that experience, Milne helped establish the Seismological Society of Japan, which held its inaugural meeting on March 11, 1880.
Soon afterward, Milne and a colleague, James Ewing, developed a seismograph and placed devices at several locations to create an observation network.
"Japanese seismology began with the purpose of finding ways to predict and lessen the damage from earthquakes," explained Jiro Tomari, a research fellow at the University of Tokyo's Earthquake Research Institute who studies the history of seismology.
The discipline's focus has changed over time.
In 1891, the Nobi Earthquake, the largest known inland earthquake in Japan, caused the government to take measures to institutionalize research, which until then had primarily been an academic pursuit. More than 7,000 people died in the quake.
The following year, the Japanese government established the earthquake investigation committee, comprising researchers from a wide range of disciplines such as geodesy and architecture.
The committee referred to historical documents to compile the Historical Record of Major Japanese Earthquakes and established earthquake resistance standards for buildings.
Fusakichi Omori, a committee member and professor of seismology at Tokyo Imperial University , drew up what came to be called "Omori's formula" to calculate the distance to an earthquake's epicenter. It marked the beginning of efforts to predict earthquakes using statistics on observational data concerning location, type and frequency.
However, these efforts were ridiculed as "overly simplistic" after the Great Kanto Earthquake took more than 100,000 lives in Tokyo and Yokohama in 1923.
Why do earthquakes happen? What is going on in the Earth's interior?
Seismology changed course to solve these puzzles through physics, an effort that was based at Tokyo Imperial University's Earthquake Research Institute. Kyoto Imperial University and the Central Meteorological Observatory discovered the existence of "deep-focus earthquakes" that occur far below the Earth's surface.
After World War II, the study of earthquakes began to focus on prediction.
The background to this was the 1944 Tonankai Earthquake, which was followed by the Nankai Earthquake in 1946.
In Tokyo, the General Headquarters (GHQ) of the Allied occupation forces established the coordinating committee for earthquake prediction and research. Prediction became a national undertaking. The first earthquake prediction plan went into effect the year after the 1964 Niigata Earthquake.
In 1976, Katsuhiko Ishibashi, professor emeritus at Kobe University who was then a research associate at the University of Tokyo, came up with a disturbing theory.
"It wouldn't be strange if (a Tokai earthquake) struck within the next several years," he said. This led to the enactment of the Law on Special Measures Concerning Countermeasures for Large-Scale Earthquakes, which was premised on the ability to predict imminent earthquakes.
Meanwhile, research into disaster readiness, such as investigations into the vibrations created by earthquakes, received a cold reception. It was regarded as "useless for prediction."
Opinions changed after the 1995 Great Hanshin Earthquake that leveled much of Kobe, killing more than 6,400 people.
Research into earthquake prediction had failed to help reduce casualties. After a stint of 20 years, the Headquarters for Earthquake Prediction Promotion was abolished.
"After Hanshin, researchers started to think much more about the connection between their work and disaster readiness and society," said Yasuhiro Umeda, professor emeritus at Kyoto University, reflecting on the disaster. Active fault surveys and earthquake observation networks were enhanced, and maps were created to show projected intensity of shaking. The Earthquake Early Warning system also came into being at this time.
Basic research continues at the Headquarters for Earthquake Research Promotion, the successor to the prediction promotion headquarters.
It is possible to make assumptions on the scale and location of future major earthquakes.
Post-Hanshin research gave scientists more confidence. Then the Great East Japan Earthquake struck. It caught everybody unawares.
For the past year, the government has been reviewing its assumptions about earthquakes and its methods for releasing information.
As part of that effort, it has decided to enhance seafloor observation networks.
However, the enormous budget devoted to research since the Hanshin earthquake has drawn much criticism. Critics say the funds are ostensibly related to disaster readiness, but in fact have no direct bearing on this aspect at all.
"We need to shake up seismology so much that it rewrites the textbooks on the subject," said Takeshi Sagiya, a professor of geodesy at Nagoya University. "We should shift attitudes away from the heavy emphasis on just basic research and instead perform more evaluations of disaster readiness and strengthen our collaboration with other fields of research."
The Seismological Society of Japan will soon draw up a proposal and publish it.