If I want to know something about earthquakes,
the first websites I go to are: the USGS Real Time Earthquakes
Website or the IRIS monitoring website.
This week we are exploring seismicity and what
countries do to prevent/mitigate the hazard.
The new 2014 US map of
seismicity (see image from USGS) shows the (obvious, in pink) ring of fire
portion on the West coast but also a central area in the middle of the plate. This area, called
the New Madrid
Zone was shaken by a M8(!) in 1811.
The reason for the activity is a very old intraplate rift placed below the area
(see image from http://showme.net).
There is a brand
new effort by the USGS: the ShakeAlert system, developed for the West coast using some
of the existing systems. Today, the technology exists to detect earthquakes, so
quickly, that an alert can reach some areas before strong shaking arrives. The
purpose of an EEW (Earthquake Early Warning) system is to identify and
characterize an earthquake a few seconds after it begins, calculate the likely
intensity of ground shaking that will result, and deliver warnings to people
and infrastructure in harm’s way. Studies
of earthquake early warning methods in California have shown that the warning
time would range from a few seconds to a few tens of seconds, depending on the
distance to the epicenter of the earthquake.
A few seconds of warning might make all the
difference (enough to stop transit/elevators and to drop, cover, hold on).
All for now-
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