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 Seismic Intensity |
Seismic intensity describes the scale of the ground motion at a particular location.
It varies with the distance from the epicenter and the surface geology at each point.
JMA's seismic intensity scale has 10 degrees
(0 (imperceptible), 1, 2, 3, 4, 5 lower, 5 upper, 6 lower, 6 upper, 7).
The seisimic intensity is measured with a seisimic intensity meter.
"Tables explaining the JMA Seismic Intensity Scale" describes the situations and damage which may be caused by
seismic motion of each seismic intensity.
- Tables explaining the JMA Seismic Intensity Scale New!
- Summary of Tables explaining the JMA Seismic Intensity Scale (PDF 197 KB) New!
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Seismic intensity |
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| Tsunami Warning |
The immediate provision of tsunami warning for coastal regions
is essential in reducing and mitigating the catastrophic losses that such
waves can bring. In the event of an earthquake that has the potential to
generate a tsunami, JMA issues a tsunami warning within three minutes of
the quake. For tsunamis formed by seismic activity far from Japan, the Agency
acts in coordination with the Pacific Tsunami Warning Center (PTWC) in Hawaii
and issues a long-propagating tsunami warning. JMA operates the Northwest
Pacific Tsunami Advisory Center, which provides more tailored tsunami
information for countries in the Northwest Pacific region in cooperation with
PTWC.
- Tsunami Warnings and Advisories |
Time sequence for issuing earthquake and tsunami information
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| Prediction and Information Services for the Tokai Area |
Although earthquake prediction generally
remains in the research stage, the mechanism of occurrence of the expected
Tokai Earthquake is rather well understood. An earthquake is anticipated in
the near future judging from the regionfs periodicity of occurrence, and
is expected to cause extensive damage to the Tokai area and its vicinity.
JMA handles the responsibility of providing information on the Tokai Earthquake,
including its prediction, according to the Large-Scale Earthquake Countermeasures
Act. To fulfill this responsibility, JMA operates a dense observation network
in the Tokai area and its vicinity to enable centralized monitoring in cooperation
with the agencies and institutions concerned. If an anomaly is detected in the
observational data, JMA issues information on a possible Tokai Earthquake. If the
anomaly exceeds a certain threshold, the Agency immediately convenes the Earthquake
Assessment Committee for Areas under Intensified Measures against Earthquake
Disasters, and examines whether or not the anomaly is a precursor of the Tokai
Earthquake. Based on the Committee's conclusion that a large-scale earthquake could
occur, the Director-General of JMA reports the earthquake prediction information to
the Prime Minister. Subsequently, the Prime Minister issues a Precautionary Warning
after consulting the Cabinet Council. Central and local authorities as well as
relevant sectors begin the implementation of emergency plans for the occurrence of
the Tokai Earthquake.
- Prediction of the Tokai Earthquake |
Tokai area monitoring network |
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| Volcanoes |
 Monitoring of Volcanic Activity
There are 108 active volcanoes in Japan that produce an annual average
of 15 volcanic events including eruptions, some of which seriously disrupt
socio-economic life. To continuously monitor the volcanic activity, JMA has
seismographs and relevant observation instruments stationed around 30
active volcanoes, and mobile observation teams are sent to other volcanoes
for regular patrols. When volcanic anomalies are detected through routine
monitoring or observation by the mobile teams, JMA reinforces its monitoring
and observation to enable the publication of volcano information and regular
bulletins.
Coordinating Committee for the Prediction of Volcanic Eruptions
The Coordinating Committee for Prediction of Volcanic Eruptions was
established in 1974 under the Volcanic Eruption Prediction Plan of the Japanese
Government. The Committee is comprised of experts from academic communities and
related organizations, and JMA serves as its secretariat. The Committee
periodically reviews volcanic activity in Japan and provides an outlook on
volcanic eruptions when required.
- Volcano Information
- Brochure: JMA Volcanic Warnings and Volcanic Alert Levels (PDF 907 kB)
- Homepage of Tokyo Volcanic Ash Advisory Center (VAAC)
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Volcanic Observations and Information Center
In order to detect unusual volcanic phenomena and issue volcano information
as appropriate, JMA operates Volcanic Observations and Information Centers at
its Headquarters and at the Sapporo, Sendai and Fukuoka District Meteorological
Observatories (DMOs). These centers integrate a range of observation data and
monitor the activity of volcanoes in their areas of responsibility.
Active volcanoes in Japan |
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| Other brochures |
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