MILESTONES IN SEISMOLOGY IN THE WORLD
History of seismology
Far back in history, people have tried to explain why earthquakes occur. The Chinese were the first to build an instrument for registering earthquakes. This and following events are described in the following.
Ca 132 BC:
First seismoscope, showing the direction of incoming earthquake waves, is developed in China
The first seismometer is invented by Filippo Cecchi in Italy.
A distant earthquake is recorded instrumentally for the first time. The recording is made in Potsdam, Germany of a Japanese earthquake.
John Milne develops a seismometer, which is installed at ca. 40 observatories around the world. This is the beginning of global earthquake monitoring.
1906: Richard Oldham discovers Earth’s core by studying seismic waves.
Andrija Mohorovicic discovers the moho discontinuity, which is the boundary between Earth’s crust and mantle.
Charles Richter develops the magnitude scale (the so-called “Richter’s magnitude scale”), which is used for determining the size of earthquakes as applied in Southern California.
Inge Lehmann from Denmark discovers the Earth’s inner core.
1946: A nuclear explosion is recorded by a seismograph for the first time.
1960: The largest recorded earthquake occurs in Chile, with a magnitude M=9.5.
1961: The World-Wide Standardized Seismic Network (WWSSN) is established for monitoring both earthquakes and nuclear testing. The Norwegian station KONO at Kongsberg is installed as part of the network in 1962. WWSSN has played a central role in supplying data supporting the theory of continental drift and plate tectonics, which helps understanding the fundamental deformational processes of the Earth. WWSSN is later taken over by IRIS (Incorporated Research Institutions for Seismology) and now continues as the Global Seismic Network (GSN).
1977: Hiroo Kanamori establishes the moment magnitude scale, which is a measure of earthquake magnitude based on seismic moment. The moment magnitude scale is used by most seismologists today.
The Comprehensive Nuclear-Test-Ban Treaty (CTBT) is established. As of 2005, the treaty is signed by 174 countries. At the same time, the International Data Center is established in Vienna, coordinating the monitoring in connection to the treaty. Seismic monitoring is done through the International Monitoring System (IMS). The map shows the global network of stations that are part of GSN and IMS.
Milestones in seismology in Norway
In Norway, seismology has been an active science since the 1830s where B.M. Keilhau started studying earthquakes. The most important events for seismology in Norway throughout the times are outlined below.
1819: On August 31st, a large earthquake is registered close to Lurøy, Northern Norway. This is the largest earthquake in NW-Europe in historical time with a magnitude of M=5.8.
1836: B.M. Keilhau publishes ”Etterretninger om jordskjelv i Norge” describing Norwegian earthquakes until 1834.
Hans Reusch, director of the Norwegian Geological Survey (NGU), starts systematic investigations of Norwegian earthquakes.
1888: T.Ch. Thomassen publishes ”Berichte über die wesentlich seit 1834 in Norwegen eingetroffenen Erdbeben” covering Norwegian earthquakes in the time 1834-1887.
1899: Bergen Museum takes over the systematic investigations of earthquakes.
C.F. Kolderup applies, for the first time, for funding of a seismograph in Bergen –the application is rejected.
1904: On October 23rd a large earthquake occurs in the Oslofjord, M=5.4. Norway joins the international convention of states for the advancement of earthquake research, and funding for the installation of a seismograph in Bergen is granted.
The first seismic station in Norway, a two-component Bosch-Omori seismograph, is installed in the basement at Bergen Museum. The instrument is in use until 1959. During the first 10 years, ca. 70 earthquakes are recorded. The first earthquake (in Western Mongolia) is registered in Bergen on July 9th.
A Wiechert horizontal seismograph (2 components) is installed in Bergen Museum.
1923: A vertical seismometer is installed in Bergen Museum. The Seismological Observatory is established with its first office located at Joachim Frieles gate 1.
1946: April 9th: The Norwegian government decides to establish a university in Bergen. The university takes over the systematic investigations of earthquakes from its opening.
July: The first seismic station outside Bergen is installed with a Willmore vertical seismometer at Isfjorden on Svalbard (Spitsbergen).
1959: US Coast and Geodetic Survey donates a 3-component Benioff seismograpf with a film recorder, which is installed in Tromsø Museum. The first homemade-seismograph is put in operation in Bergen.
1960: The Seismological Observatory (Jordskjelvstasjonen) becomes an independent university institute.
1961: The first seismic station in installed on Jan Mayen. In March, the Seismological Observatory moves to Villaveien 9.
1962: During the Skagerrak project, the Seismological Observatory through a seismic survey detects for the first time rocks on the Norwegian Continental Margin, capable of containing oil and gas. This is the beginning of the Norwegian oil adventure.
1963: US Coast and Geodetic Survey, in cooperation with UiB, installs a seismic array in Lillehammer for research on identification of explosions.
1968-70: NORSAR (Norwegian Seismic Array) is established with a seismic array at Mjøsa and data-/research center at Kjeller. NORSAR was established as a research institution in cooperation between the Seismological Observatory and the Foreign Department. NORSAR is mainly established for monitoring nuclear testing. NORSAR is today an independent institution which, in addition to operating arrays, also conducts consultant work in seismology.
1977: Jordskjelvstasjonen moves to the Science Building (Realfagbygget).
1990: Earthquake monitoring, seismological research and teaching move to the newly established Department of Solid Earth Physics, which is created by joining the Seismological Observatory and part of the Geophysical Institute (Division on earth magnetism and paleomagnetism).
The Norwegian National Seismic Network (NNSN) is established based on the former Western-, Southern- and Northern networks and single stations operated by the University of Bergen. The network is funded by the University of Bergen and the Norwegian Oil Industry Association (OLF). The map shows stations, which were part of the network when it was established. Blue triangles are NNSN stations, red triangles are NORSAR arrays.
2003: Earthquake monitoring and seismological teaching and research moves to the Department of Earth Science, which is established by merging the Institute of Solid Earth Physics and the Geological Institute.
The high competence in seismology in Norway has resulted in:
* Teaching programs for Norwegian and foreign students, today UiB has the largest seismology program in the Nordic countries.
* Oil related research and education had a ‘flying start’ with an important contribution from seismology when the large oil reserves were discovered on the Norwegian continental margin. These activities have been continued and today Norway is one of the World’s leading countries in oil-related research.
* Many international projects in seismology are conducted by UiB and NORSAR
* Development of software at UiB, which is in use in more than 50 countries.
* Projects in developing countries with large seismic hazard.
* Research on Norwegian and global problems related to seismology.