[Music]
from above the planet appears eerily
still but every mountain range and every
chasm on its face is a scar with many
telling a story of when the earth
rumbled to life earthquakes occur around
the world they’ve been recorded on all
seven continents but most quakes take
place in just three regions the
mid-atlantic ridge an underwater line
that runs down the Atlantic Ocean the
alpide belt which stretches from the
Mediterranean to Southeast Asia and the
circum-pacific belt which traces along
the edges of the Pacific Ocean and is
where about 80% of all earthquakes occur
these areas experience the most
earthquakes due to what lies beneath the
surface
earthquakes are the result of pressure
specifically pressure caused by extreme
stress in the Earth’s crust that stress
can be caused by volcanic activity or
even man-made activities in certain
areas
however most earthquake inducing stress
is caused by the movement of tectonic
plates tectonic plates are constantly
moving either against away along or
underneath each other but sometimes
their edges may catch and stick the
plates however continue to move or at
least attempt to energy from this
attempted movement fields around the
edges sticking point creating immense
pressure until the edges are forced to
let go and the plates slip this causes a
sudden and powerful release of energy so
powerful that it breaks the Earth’s
crust this fracturing emits shockwaves
through the ground and causes intense
vibrations or quakes in fact the world’s
most earthquake-prone regions are where
the most geologically active plates meet
[Music]
earthquakes or any seismic activity are
recorded by seismographs when the ground
shakes seismographs oscillate drawing a
jagged line to reflect this movement the
more extreme the earthquake the greater
the height of the jagged line these
recorded motions are then used to
measure the earthquake strength or
magnitude while several scales of
magnitude exist the one seismologist
prefer is the moment magnitude scale it
has no upper limit and it measures
earthquakes logarithmic ly this means
that each magnitude on its scale is ten
times greater than the one before it
unlike the now rarely used Richter scale
the moment magnitude scale can be
applied globally and can measure quakes
of the highest magnitudes the largest
recorded earthquake occurred near
Bolivia Chile in 1960 nestled within the
circum-pacific belt the Valdivia
earthquake was the most powerful in a
series of quakes that struck the region
measuring at a magnitude of about 9.5 in
addition to causing devastating tremors
on land the earthquake also generated a
deadly tsunami reaching up to 80 feet
high the tsunami raced across the
Pacific Ocean
hitting faraway countries like the
Philippines and Japan in fact data from
seismographs showed that the shock waves
emitted by the Valdivia earthquake
continued to shake the entire planet for
days some earthquake prone areas have
adapted various ways to protect their
communities buildings and bridges are
designed to sway rather than break when
an earthquake occurs the public is
educated on how to protect themselves
during a seismic event and government
officials enact drills to ensure the
protection of their people earthquakes
can leave behind incredible devastation
but these same forces have also created
magnificent features with each adding
character to a planet so unique
[Music]
