Timing
The window of time from the announcement of an Earthquake Early
Warning until the arrival of the main tremors is very short, i.e. a
matter of seconds (or between several seconds and a few tens of
seconds).
In areas that are close to the focus of the earthquake, the warning may not be transmitted before strong tremors hit.
False alarms
When using data from only one seismograph, false Earthquake Early
Warnings may occur as a result of noise from accidents, lightning or
device failure.
Magnitude estimation
There are limits to the accuracy of estimating magnitude, especially for large earthquakes.
It is difficult to separate earthquakes and provide accurate warnings
when multiple earthquakes occur almost simultaneously or in close
proximity to each other.
Seismic intensity estimation
There are limits to the accuracy of estimating seismic intensity by
statistical attenuation formula, as well as limits to the prediction of
land surface amplification.
The Japan Meteorological Agency plans to continue improving the
accuracy and timing of the Earthquake Early Warning through joint
research with the National Research Institute for Earth Science and
Disaster Prevention, and also intends to make further efforts toward
publicizing the Earthquake Early Warning.
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