Many Fear Of Another
Major Earthquake
The fear by many is the
possibility of a second
major earthquake or "terremoto
gemelo" is explained by
a geologist for the Red
Sismológica Nacional (RSN).
The Spanish language
daily reported earlier
this week explained the
history of "terremoto
gemelos" (twin
earthquakes) in the
country.
The terremoto gemelos,
according to Guillermo
Alvarado, geologist for
the Red Sismológica
Nacional (RSN) of the
Universidad de Costa
Rica (UCR) and the
Instituto Costarricense
de Electricidad (ICE),
are when two earthquakes
have the same
destructive power within
a close period of time.
Alvarado explained the
destruction of Cartago,
east of San José, in
1842 when two
destructive earthquakes
hit the area six months
apart. And the
earthquake of 1920, also
in Cartago, that
occurred 21 days apart.
In 1911 and 1912 the
earthquakes of the Toro
Amarillo were spaced at
10 months apart. And the
earthquake of December
22, 1990, in Alajuela
was followed up by
another seven months
later in Puriscal, on
the south side of
Alajuela.
Alvarado was quick to
say that that is the
history of terremoto
gemelos in the country
and does not mean such
will be the case this
time, but did not
discard the possibility
either.
The geologist explained
that when one local
fault, as the case of
the January 8 earthquak,
it releases energy and
activates other local
faults. In Costa Rica
there are some 1.000
local faults, but only
150 are of grave concern
and can unleash
tremendous destruction.
Alvarado went further in
his explanation, saying
that that is the case in
the earthquake of
January 8 with the
epicentre in Cinchona,
it activated the fault
in the area of the Poás
volcano and responsible
for the tremors with the
epicentre in the area of
Bajos de Toro Amarillo
and the Horquetas de
Sarapiquí.
According to data by the
RSN in the 19th and 20th
century, Costa Rica has
suffered a total of 48
earthquakes, one every
four years, on average.
27 of the earthquakes
were caused by
subduction or shocks
between tectonic plates,
the last being in the
area of Damas, near
Quepos, in 2004.
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