Fusakichi Omori
Encyclopedia
was a pioneer Japan
ese seismologist, second chairman of seismology at the Imperial University of Tokyo and president of the Japanese Imperial Earthquake Investigation Committee.
serving as professors at the Imperial University of Tokyo, especially John Milne
until he left Japan in 1895, as well as Japanese colleagues including Seikei Sekiya
who in 1880 became the first professor of seismology
at any university in the world at Tokyo Imperial University.
, obtained by their measuring devices at the University. In 1886 Sekiya was made chair of seismology and secretary to the Imperial Earthquake Investigation Committee and by the time of his death a decade later, Japan had nearly 1000 seismological recording stations to study seismicity in Japan.
In 1891 Omori was appointed assistant to Sekiya and in 1893 lecturer on seismology at the Imperial University. In 1895, he was sent to Germany
and Italy
for additional study and visited England
briefly on his way home in September, 1896.
Omori became chair of seismology at the University and secretary of the Imperial Earthquake Investigation Committee following Sekya's death on 9 January 1896. He could read English, German, Italian and Japanese and maintained correspondence with many seismologists as well as writing papers in all four languages.
and with minor modifications by the J&A Bosch Company of Strassburg, the "Bosch-Omori Seismometer". Distributed worldwide, Bosch-Omori seismographs formed the backbone of the world seismographic network until after World War II.
provinces were devastated by earthquakes, whose fault line was traced by Bunjiro Koto (1856–1935), another professor at Imperial University. He found the strike-slip fault cut the surface for at least 40 miles and that the north-east side had shifted relative to the other side a distance of one to two meters. Some areas had 18 to 20 foot high scarps, others looked like a linear mole had been at work. This earthquake provided an initial data set which, when correlated with other earthquakes, revealed that aftershock
frequency decreases by approximately the reciprocal of time after the main shock, a mathematical formula now called "Omori's law."
Omori conducted measurements of the three principal phases of earthquake motion originally described by Milne: the preliminary tremors, the main portion and the end portion, and visited areas after major earthquakes to ground verify the data collected by his instruments. Omori arrived in Taiwan shortly after the 17 March 1906 Meishan earthquake
, later describing soil liquefaction
and the complete destruction of Meishan town. He ascribed the high number of casualties due to structure collapse of the dominant local building type: sun-dried brick walls loosely cemented with mud and overlaid by heavy roof beams.
Omori is recognized in earthquake engineering
as the first to research the effects of earthquakes on man-made structures with shaking tables
and compare experimental results with measurements during actual earthquakes.
At the 1908 Messina earthquake
, Omori noted the large loss of life, perhaps 75,000 and said that of those 99 percent had died because their houses were not built to withstand earthquakes.
. Seismologists from around the world arrived in northern California
shortly after the disaster.
Omori left Tokyo 1 May by ship and arrived in San Francisco
18 May at the head of an Imperial committee of architects and engineers including Professors Tatsutaro Nakamura and Toshikata ("Riki") Sano to study the aftermath of the San Francisco earthquake and to give a new seismograph to the University of California
. Another member of the committee was an architect, Magoichi Noguchi.
Omori and his colleagues spent time in the city measuring damaged buildings and taking photographs. They were reportedly assaulted on more than one occasion. At least two authors state that Omori and colleagues were attacked on Mission Street, San Francisco by a gang of men and youths who were later hailed by the local press for their anti-Japanese
racist stoning and slugging of random Japanese men, however contemporary sources indicate that one boy involved in the stoning of Dr. Omori worked for the Post Office as a messenger was fired by Postmaster Fisk of San Francisco when the Japanese Association of America protested. Other incidents alleged in a letter to the newspaper are unreferenced by any other sources, and Omori himself chose to forgive writing, "referring to some trouble I had with hoodlums in San Francisco. I was very glad to see that the people of Hawaii did not like to have me treated in that way, but then it did me no injury and I bear no malice. There are hoodlums in all countries. The people of California treated me extremely well and I am very much pleased with my trip."
During the approximately 80 days spent in California, Omori traveled by steamer as far north as Humboldt County, California
where on 6 July 1906 he was struck by a ruffian who mistook him for a non-union strikebreaking sailor in Eureka, California
.
and the mayor of Eureka promptly apologized to Dr. Omori.
Omori continued his observations south into the Eel River Valley, stopped in Ferndale, California
and noted a giant landslide south of Centerville
at False Cape
which covered the former coast road and created a new promontory
into the Pacific Ocean
as well as damages to local property and buildings. Leaving Ferndale, Omori continued a careful inventory of man-made and natural features as he followed the trace of the San Andreas fault
south to San Francisco by land.
Along the way he noticed the reaction of ground, buildings and trees to the earthquake, noting that "even large redwoods trees were split by the shearing motion of the ground."
In person, and in his writings, Omori followed the visible land trace of the fault 150 miles south to San Jose
from Point Arena
, but pointed out that the line continued 120 miles northward, underwater to the False Cape landslide south of Eureka, California. Many of Omori's photographs from this trip were published.
Omori studied the directions of the movement by studying tombstones south of San Francisco, and cracks in the walls of buildings including the St. James Hotel in San Jose. Correlating damages in Western and Japanese construction, Omori released the first scale of earthquake damages that used instrument readings as well as observed effects to describe damages. Omori described the faulting in California as parallel to the strike of the fault caused by shear stresses on the plane of fracture. Omori seismographs were rapidly installed all over northern California, and a list of aftershocks to the San Francisco earthquake was compiled and published. Omori returned to Japan 4 August 1906 aboard the Doric.
in 1893 to his death, Omori studied Japanese volcanos. He described several types of volcanic earthquakes from data obtained at regular eruptions of Mount Asama
in central Japan, the 1910 Mount Usu
eruption and the 12 January 1914 eruption of Sakurajima
. At the latter two eruptions, his warnings to the population prevented greater loss of life.
After meeting Thomas Jaggar
of the Massachusetts Institute of Technology
who was planning a volcanic observatory on the Big Island of Hawaii, Omori designed the foundations and seismograph emplacement for the Whitney Laboratory of Seismology, building 29 near Volcano House
, now part of the Hawaiian Volcano Observatory
, state historic site 10-52-5506 and National Register of Historic Places
site 74000292, added 24 July 1974. In 1912 Omori shipped to Hawaii two instruments, an Omori-type Horizonal Tromometer and a seismograph, to be placed on the specially built foundations. A year later, two more Bosch-Omori seismographs were donated to the HVO by the Massachusetts Institute of Technology.
, the director of the observatory at Riverview College in Sydney, Australia observed a seismograph record the major great Kantō earthquake
which destroyed Yokohama
and Tokyo on 1 September 1923, killing about 140,000 and leaving 1.9 million people homeless.
Omori returned to Japan from Melbourne, Australia on board the Tenyo Maru on 4 October 1923. Shortly thereafter, he was diagnosed with a brain tumor and entered the university hospital where received the Order of the Sacred Treasure
from the Imperial Court a few days before his death at age 55 on 8 November 1923.
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
ese seismologist, second chairman of seismology at the Imperial University of Tokyo and president of the Japanese Imperial Earthquake Investigation Committee.
Education
Omori studied physics with the initial British foreign advisorsO-yatoi gaikokujin
The Foreign government advisors in Meiji Japan, known in Japanese as oyatoi gaikokujin , were those foreign advisors hired by the Japanese government for their specialized knowledge to assist in the modernization of Japan at the end of the Bakufu and during the Meiji era. The term is sometimes...
serving as professors at the Imperial University of Tokyo, especially John Milne
John Milne
For other uses, see John Milne .John Milne was the British geologist and mining engineer who worked on a horizontal seismograph.-Biography:...
until he left Japan in 1895, as well as Japanese colleagues including Seikei Sekiya
Sekiya Seikei
, alternatively Sekiya Kiyokage, was a Japanese geologist, one of the first seismologists, influential in establishing the study of seismology in Japan and known for his model showing the motion of an earth-particle during an earthquake....
who in 1880 became the first professor of seismology
Seismology
Seismology is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other planet-like bodies. The field also includes studies of earthquake effects, such as tsunamis as well as diverse seismic sources such as volcanic, tectonic, oceanic,...
at any university in the world at Tokyo Imperial University.
Early career
Sekiya and Omori published the first clear record of a destructive earthquakeEarthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...
, obtained by their measuring devices at the University. In 1886 Sekiya was made chair of seismology and secretary to the Imperial Earthquake Investigation Committee and by the time of his death a decade later, Japan had nearly 1000 seismological recording stations to study seismicity in Japan.
In 1891 Omori was appointed assistant to Sekiya and in 1893 lecturer on seismology at the Imperial University. In 1895, he was sent to Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
and Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
for additional study and visited England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
briefly on his way home in September, 1896.
Omori became chair of seismology at the University and secretary of the Imperial Earthquake Investigation Committee following Sekya's death on 9 January 1896. He could read English, German, Italian and Japanese and maintained correspondence with many seismologists as well as writing papers in all four languages.
Recording seismographs
In 1899, Omori described his horizontal recording pendulum, later called an Omori seismometerSeismometer
Seismometers are instruments that measure motions of the ground, including those of seismic waves generated by earthquakes, volcanic eruptions, and other seismic sources...
and with minor modifications by the J&A Bosch Company of Strassburg, the "Bosch-Omori Seismometer". Distributed worldwide, Bosch-Omori seismographs formed the backbone of the world seismographic network until after World War II.
Global earthquake investigations
28 October 1891 Mino and Owari1891 Mino-Owari earthquake
The was a large earthquake that struck the former provinces of Mino and Owari in the Nōbi Plain area during the Meiji period in Japan. It is also referred to as the Nōbi Earthquake or the Great Nōbi Earthquake . It is the largest known inland earthquake in Japan.-History:The earthquake struck on...
provinces were devastated by earthquakes, whose fault line was traced by Bunjiro Koto (1856–1935), another professor at Imperial University. He found the strike-slip fault cut the surface for at least 40 miles and that the north-east side had shifted relative to the other side a distance of one to two meters. Some areas had 18 to 20 foot high scarps, others looked like a linear mole had been at work. This earthquake provided an initial data set which, when correlated with other earthquakes, revealed that aftershock
Aftershock
An aftershock is a smaller earthquake that occurs after a previous large earthquake, in the same area of the main shock. If an aftershock is larger than the main shock, the aftershock is redesignated as the main shock and the original main shock is redesignated as a foreshock...
frequency decreases by approximately the reciprocal of time after the main shock, a mathematical formula now called "Omori's law."
Omori conducted measurements of the three principal phases of earthquake motion originally described by Milne: the preliminary tremors, the main portion and the end portion, and visited areas after major earthquakes to ground verify the data collected by his instruments. Omori arrived in Taiwan shortly after the 17 March 1906 Meishan earthquake
1906 Meishan earthquake
The 1906 Meishan earthquake was a magnitude 7.1 earthquake which occurred on March 17, 1906 and was centred on Meishan, Chiayi, Jiayi County, Taiwan...
, later describing soil liquefaction
Soil liquefaction
Soil liquefaction describes a phenomenon whereby a saturated soil substantially loses strength and stiffness in response to an applied stress, usually earthquake shaking or other sudden change in stress condition, causing it to behave like a liquid....
and the complete destruction of Meishan town. He ascribed the high number of casualties due to structure collapse of the dominant local building type: sun-dried brick walls loosely cemented with mud and overlaid by heavy roof beams.
Omori is recognized in earthquake engineering
Earthquake engineering
Earthquake engineering is the scientific field concerned with protecting society, the natural and the man-made environment from earthquakes by limiting the seismic risk to socio-economically acceptable levels...
as the first to research the effects of earthquakes on man-made structures with shaking tables
Earthquake shaking table
There are several different experimental techniques that can be used to test the response of structures to verify their seismic performance, one of which is the use of an earthquake shaking table...
and compare experimental results with measurements during actual earthquakes.
At the 1908 Messina earthquake
1908 Messina earthquake
The 1908 Messina earthquake and tsunami took some 100,000–200,000 lives on December 28, 1908 in Sicily and Calabria, southern Italy.-Quake:On December 28, 1908 from about 05:20 to 05:21 an earthquake of 7.2 on the moment magnitude scale occurred centered on the of city Messina, in Sicily. Reggio...
, Omori noted the large loss of life, perhaps 75,000 and said that of those 99 percent had died because their houses were not built to withstand earthquakes.
San Francisco Earthquake 1906
Worldwide, the two most common types of seismographs at the time, the Milne-type and Bosch-Omori seismographs recorded the San Francisco earthquake1906 San Francisco earthquake
The San Francisco earthquake of 1906 was a major earthquake that struck San Francisco, California, and the coast of Northern California at 5:12 a.m. on Wednesday, April 18, 1906. The most widely accepted estimate for the magnitude of the earthquake is a moment magnitude of 7.9; however, other...
. Seismologists from around the world arrived in northern California
Northern California
Northern California is the northern portion of the U.S. state of California. The San Francisco Bay Area , and Sacramento as well as its metropolitan area are the main population centers...
shortly after the disaster.
Omori left Tokyo 1 May by ship and arrived in San Francisco
San Francisco, California
San Francisco , officially the City and County of San Francisco, is the financial, cultural, and transportation center of the San Francisco Bay Area, a region of 7.15 million people which includes San Jose and Oakland...
18 May at the head of an Imperial committee of architects and engineers including Professors Tatsutaro Nakamura and Toshikata ("Riki") Sano to study the aftermath of the San Francisco earthquake and to give a new seismograph to the University of California
University of California, Berkeley
The University of California, Berkeley , is a teaching and research university established in 1868 and located in Berkeley, California, USA...
. Another member of the committee was an architect, Magoichi Noguchi.
Omori and his colleagues spent time in the city measuring damaged buildings and taking photographs. They were reportedly assaulted on more than one occasion. At least two authors state that Omori and colleagues were attacked on Mission Street, San Francisco by a gang of men and youths who were later hailed by the local press for their anti-Japanese
Anti-Japanese sentiment
Anti-Japanese sentiment involves hatred, grievance, distrust, dehumanization, intimidation, fear, hostility, and/or general dislike of the Japanese people and Japanese diaspora as ethnic or national group, Japan, Japanese culture, and/or anything Japanese. Sometimes the terms Japanophobia and...
racist stoning and slugging of random Japanese men, however contemporary sources indicate that one boy involved in the stoning of Dr. Omori worked for the Post Office as a messenger was fired by Postmaster Fisk of San Francisco when the Japanese Association of America protested. Other incidents alleged in a letter to the newspaper are unreferenced by any other sources, and Omori himself chose to forgive writing, "referring to some trouble I had with hoodlums in San Francisco. I was very glad to see that the people of Hawaii did not like to have me treated in that way, but then it did me no injury and I bear no malice. There are hoodlums in all countries. The people of California treated me extremely well and I am very much pleased with my trip."
During the approximately 80 days spent in California, Omori traveled by steamer as far north as Humboldt County, California
Humboldt County, California
Humboldt County is a county in the U.S. state of California, located on the far North Coast 200 miles north of San Francisco. According to 2010 Census Data, the county’s population was 134,623...
where on 6 July 1906 he was struck by a ruffian who mistook him for a non-union strikebreaking sailor in Eureka, California
Eureka, California
Eureka is the principal city and the county seat of Humboldt County, California, United States. Its population was 27,191 at the 2010 census, up from 26,128 at the 2000 census....
.
and the mayor of Eureka promptly apologized to Dr. Omori.
Omori continued his observations south into the Eel River Valley, stopped in Ferndale, California
Ferndale, California
Ferndale is a city in Humboldt County, California, United States. Known for its well-preserved Victorian buildings, the city's population was 1,371 at the 2010 census, down from 1,382 at the 2000 census...
and noted a giant landslide south of Centerville
Centerville, Humboldt County, California
Centerville is a former settlement in Humboldt County, California. It was located west of Ferndale, at an elevation of 13 feet ....
at False Cape
Capetown, California
Capetown is a locality in Humboldt County, California. It is located on the Bear River northeast of Cape Mendocino, at an elevation of ....
which covered the former coast road and created a new promontory
Promontory
Promontory may refer to:*Promontory, a prominent mass of land which overlooks lower lying land or a body of water*Promontory, Utah, the location where the United States first Transcontinental Railroad was completed...
into the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
as well as damages to local property and buildings. Leaving Ferndale, Omori continued a careful inventory of man-made and natural features as he followed the trace of the San Andreas fault
San Andreas Fault
The San Andreas Fault is a continental strike-slip fault that runs a length of roughly through California in the United States. The fault's motion is right-lateral strike-slip...
south to San Francisco by land.
Along the way he noticed the reaction of ground, buildings and trees to the earthquake, noting that "even large redwoods trees were split by the shearing motion of the ground."
In person, and in his writings, Omori followed the visible land trace of the fault 150 miles south to San Jose
San Jose, California
San Jose is the third-largest city in California, the tenth-largest in the U.S., and the county seat of Santa Clara County which is located at the southern end of San Francisco Bay...
from Point Arena
Point Arena, California
Point Arena is a small coastal city in Mendocino County, California, United States. Point Arena is located west of Hopland, at an elevation of 118 feet . The population was 449 at the 2010 census, down from 474 at the 2000 census, making it one of the smallest incorporated cities in the state...
, but pointed out that the line continued 120 miles northward, underwater to the False Cape landslide south of Eureka, California. Many of Omori's photographs from this trip were published.
Omori studied the directions of the movement by studying tombstones south of San Francisco, and cracks in the walls of buildings including the St. James Hotel in San Jose. Correlating damages in Western and Japanese construction, Omori released the first scale of earthquake damages that used instrument readings as well as observed effects to describe damages. Omori described the faulting in California as parallel to the strike of the fault caused by shear stresses on the plane of fracture. Omori seismographs were rapidly installed all over northern California, and a list of aftershocks to the San Francisco earthquake was compiled and published. Omori returned to Japan 4 August 1906 aboard the Doric.
Volcanic seismicity
From one of his earliest papers describing the eruption of Mount AzumaMount Azuma
is an active stratovolcano in Fukushima prefecture, Japan.It has a conical-shaped crater and as the name "Kofuji" suggests, the shape of Mount Azuma is like that of Mount Fuji...
in 1893 to his death, Omori studied Japanese volcanos. He described several types of volcanic earthquakes from data obtained at regular eruptions of Mount Asama
Mount Asama
is an active complex volcano in central Honshū, the main island of Japan. The volcano is the most active on Honshū. The Japan Meteorological Agency classifies Mount Asama as rank A. It stands above sea level on the border of Gunma and Nagano prefectures...
in central Japan, the 1910 Mount Usu
Mount Usu
is an active stratovolcano in the Shikotsu-Toya National Park, Hokkaidō, Japan. It has erupted four times since 1900: in 1910, 1944–45 , August 7, 1977, and on March 31, 2000. To the north lies Lake Toya...
eruption and the 12 January 1914 eruption of Sakurajima
Sakurajima
, also romanized as Sakurashima or Sakura-jima, is an active composite volcano and a former island of the same name in Kagoshima Prefecture in Kyūshū, Japan...
. At the latter two eruptions, his warnings to the population prevented greater loss of life.
After meeting Thomas Jaggar
Thomas Jaggar
Thomas Augustus Jaggar, Jr. was an American volcanologist. He founded the Hawaiian Volcano Observatory and directed it from 1912 to 1940.-Biography:...
of the Massachusetts Institute of Technology
Massachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...
who was planning a volcanic observatory on the Big Island of Hawaii, Omori designed the foundations and seismograph emplacement for the Whitney Laboratory of Seismology, building 29 near Volcano House
Volcano House
Volcano House is the name of a series of historic hotels built at the edge of the Kīlauea volcano, within the grounds of Hawai'i Volcanoes National Park on the Island of Hawai'i. The original 1877 building is listed on the National Register of Historic Places and now houses the Volcano Art Center...
, now part of the Hawaiian Volcano Observatory
Hawaiian Volcano Observatory
The Hawaiian Volcano Observatory is a volcano observatory located at Uwekahuna Bluff on the rim of Kīlauea Caldera on the Island of Hawaii. The observatory monitors four active Hawaiian volcanoes: Kīlauea, Mauna Loa, Hualālai, and Haleakalā...
, state historic site 10-52-5506 and National Register of Historic Places
National Register of Historic Places
The National Register of Historic Places is the United States government's official list of districts, sites, buildings, structures, and objects deemed worthy of preservation...
site 74000292, added 24 July 1974. In 1912 Omori shipped to Hawaii two instruments, an Omori-type Horizonal Tromometer and a seismograph, to be placed on the specially built foundations. A year later, two more Bosch-Omori seismographs were donated to the HVO by the Massachusetts Institute of Technology.
Final conference
In fall 1923 Omori attended the Second Pan-Pacific Science Congress in Australia, where he and Edward PigotEdward Pigot
Edward Francis Pigot was an Irish-born Australian Jesuit priest, seismologist and astronomer. He was president of the New South Wales branch of the British Astronomical Association in 1923-24 and a council member of the Royal Society of New South Wales from 1921 to 1929.Pigot was born in Dundrum,...
, the director of the observatory at Riverview College in Sydney, Australia observed a seismograph record the major great Kantō earthquake
1923 Great Kanto earthquake
The struck the Kantō plain on the Japanese main island of Honshū at 11:58:44 am JST on September 1, 1923. Varied accounts hold that the duration of the earthquake was between 4 and 10 minutes...
which destroyed Yokohama
Yokohama
is the capital city of Kanagawa Prefecture and the second largest city in Japan by population after Tokyo and most populous municipality of Japan. It lies on Tokyo Bay, south of Tokyo, in the Kantō region of the main island of Honshu...
and Tokyo on 1 September 1923, killing about 140,000 and leaving 1.9 million people homeless.
Omori returned to Japan from Melbourne, Australia on board the Tenyo Maru on 4 October 1923. Shortly thereafter, he was diagnosed with a brain tumor and entered the university hospital where received the Order of the Sacred Treasure
Order of the Sacred Treasure
The is a Japanese Order, established on January 4, 1888 by Emperor Meiji of Japan as the Order of Meiji. It is awarded in eight classes . It is generally awarded for long and/or meritorious service and considered to be the lowest of the Japanese orders of merit...
from the Imperial Court a few days before his death at age 55 on 8 November 1923.