the ground can open up during an
earthquake everything disappears in the
earth earthquakes don't operate like
that you should always
try to get outside when an earthquake
occurs in the midst of running you can
get
seriously injured california will fall
into the ocean
well the answer is of course not hello
i'm veronica cedillos i am
a structural engineer in by training i
am currently president at geo houses
international
my name is gerardo suarez i am a senior
scientist at the institute of geophysics
at the national university of mexico
today we are debunking myths about
earthquakes and earthquake safety
these are myths from social media
doorways are a safe place to take cover
during an earthquake and veronica i
think
you're better prepared than i am this is
uh definitely a myth
something we've heard from i think past
very old construction
and that was when the frame around doors
was actually part of the skeleton of the
building that really kept up the
buildings was a really strong part of
the structure
modern construction does not have that
in fact the doors are
not in any way stronger so they're
really not
helpful or very protective during
earthquake shaking and in fact i would
say that holding on to a door frame if
you have a swinging door during strong
earthquakes you can actually get quite
injured
there's no universal recipe
to be safe it depends on how your house
your apartment building
is built and where you live even in what
part of the city you live in
the work has to happen before the
earthquake in terms of
finding a safe place create a safe place
so
trying to figure out okay if there was
shaking looking up in your own home
and seeing what could fall over or
topple that can be heavy
this question is about the triangle of
life will it save you
you can see some of these voids after
the shaking has happened
but what you don't see is what happened
in between and so it may have been that
this very dense object with strong
shaking
might have moved quite a distance or
those
objects can actually topple and in many
cases can actually be
way more dangerous to be there if you
could get under a sturdy table
or that would probably be best
protecting your head and neck are really
important
but yes there may be some cases where
people were saved because they
accidentally were trapped
between a very strong object and perhaps
a beam or
something that fell down but i think it
is more circumstantial evidence than
anything else
earthquake proof buildings are
indestructible i want to make a
distinction between
earthquake proof and earthquake
resistance so in practice we don't
usually
design or build earthquake proof
buildings so a similarity might be
waterproof versus water resistant and i
think for a very long time
we went from really trying to ensure
that our designs
were life safe so they really were
protecting the occupants inside the
building
um now what we've learned as we've seen
earthquakes in other parts of the world
that doesn't mean that you're not going
to have damage to a building and so
it may be that after an earthquake your
building no longer functions so you can
no longer stay in it and if that happens
on a grand scale
all of a sudden you have an entire city
that can't be housed or
buildings that can be used for
businesses and so it really affects the
economy and the communities
as a whole and now there's a big
movement to try to
move towards designing not just for life
safety but actually what's called
functional recovery with the idea
that you can recover in a shorter time
span small earthquakes prevent bigger
ones from happening
well i i bear bad news for people who
believe in this because
uh you know people do say oh it's been
very active
you know lots of small earthquakes so
they're taking up the energy
that's concentrated on default and
indeed yes they're releasing some energy
and that happens in places that we call
subduction zones
where one tectonic plate goes under
another one
that there are dozens literally hundreds
of small earthquakes
in a certain time frame in a certain
place
but eventually in these active faults
you will have a major earthquake and by
major
i would just say larger than magnitude
7.5
that is required to release the energy
that has been accumulated
i think there's a misconception that
it's only the very big one
that's going to be the most dangerous
but in fact what we see is that even
with moderate earthquakes
there can be a lot of actually injuries
and death even
unreinforced chimneys we know are very
vulnerable to collapse and under very
low levels of shaking
and those falling into a household for
example can be very dangerous
we are overdue for a major earthquake so
when we say overdue
we imply that we know the earthquake
should have occurred before
and it hasn't and this is uh something
that we simply
do not know prediction versus
forecasting i think that's where we get
a little bit
of misunderstanding because we can
forecast
usually improbabilities we said there's
a probability that there'll be
this size of earthquake within this
region and so we really can't
predict specifically where and when
something will
an earthquake will occur everyone who
lives in a seismic area should be aware
everyone should have a kid at home you
need to have some water
you need to have a lamp light and so on
and so forth
okay these are myths from pop culture
you should always
try to get outside when an earthquake
occurs but for the most part
it's really this is probably not a very
safe practice to run outside during our
place shaking especially because many
times things can fall outward in the
midst of
running you can get seriously injured in
the one situation where it is a good
idea and that's an
adobe urban building that is not
strengthened
um or reinforced in some way those
buildings are particularly dangerous
when you have a heavy roof
if you're on the ground floor one of
these buildings you do want to try to
run out assuming you're running out into
a space that's open but if you're
already outside you know stay outside
kind of
you want to try to get away from from
building facades because
there can be bricks falling you want to
be very careful about that the ground
can open up during an earthquake
it is a myth that has to be debunked
this myth comes very much from
earthquake movies where you see that
during the earthquake there's a big
crack that opens and it swallows
buildings and people are cars
and then it just boom it shuts tight and
everything disappears in the earth
and this this doesn't happen earthquakes
don't operate like that in
certain type of soils cracks are formed
because of the very strong shaking
but these are very relatively shallow
cracks i mean they wouldn't swallow
not even a small cat and probably that
image was extrapolated into this
fantastic idea of of these huge
mouths swallowing everything in its
surroundings
so no the the answer is is definitely
not
in the u.s a big enough earthquake on
the west coast
could be felt on the east coast it will
be so big
that even though it's happening here in
california
you will feel it on the east coast no
that is not what we expect
it's just a big enough distance that we
don't expect for anyone to feel any
significant shaking on the east coast
from a
large earth on the on the west coast the
plates and the type of
rock that we have on the east coast
versus the west coast
they are different and so what happens
is that the type of
uh rock that we have on the east coast
the earthquake wave
seismic waves can actually travel much
further
so what happens is that in the east
coast you'll be able to perceive or
feel significant shaking actually much
further distances from
the um the epicenter of the origin of
work where the earthquake shaking
started
as opposed to the west coast where those
sex make waves actually that energy is
absorbed much quicker
and so it doesn't travel as much of a
far distance
we are able to predict earthquakes this
is a very simple answer
it is no no we cannot yet predict
earthquakes
and i added the word yet i wouldn't say
that now
it continues to be the goal of
seismology to be able to predict
earthquakes i believe the goal
of everyone who works in seismology or
in engineering seismology
is not to predict earthquakes but to be
prepared
for major earthquakes to understand the
phenomenon there
there are use of what we call earthquake
scenarios
um and what those are they're not
predictions
but they're incredibly useful in the
sense that
many times we don't see changes in codes
or anything until after there's an
earthquake and we learned
everything that went wrong we use the
tool of an
earthquake scenario so we choose a
believable earthquake that could happen
in a certain area to try to understand
what may be some of the key
vulnerabilities
around that particular city or area
whether it's the water system or the
housing
or the hospitals um to try to get ahead
and trying to
instill safer practices or actions that
will help us
address those vulnerabilities before an
earthquake or first myths
expert here the most so in tall
buildings it is always safer to be on a
lower floor
if you're in a tall building especially
in a place where the codes are usually
followed
it's likely that they're actually under
even a higher requirements in terms of
design and so
on the building is safe it doesn't it
doesn't matter too much where you are
that being said if there is more
movements that's when there
is really really important to make sure
that the contents within your
house or whatever the office building
are secured
and that they can't you know fall over
and topple over and hurt you
california will fall into the ocean well
the answer is of course
not you know california would not fall
into the ocean
part of california the westernmost
sliver
of california it sits on the pacific
plate
whereas the rest of california sits on
the north american
plate and these two plates move
one relative to one another at a rate of
about five to six centimeters per year
so yes when people say los angeles is
going to end up
near anchorage well yes eventually but
in many millions of years okay there is
such thing
as earthquake weather but no there is no
season for earthquakes
there is no weather for earthquakes and
there is no specific time
for earthquakes you might be thinking of
a very very convenient time that an
earthquake would happen it might be very
inconvenient
when you think about earthquake shaking
you have to think about different times
of the year and different times of the
day
you might be sleeping or it might be
winter it might be
raining and so the danger is that you're
not thinking of kind of
all these scenarios bigger earthquakes
happen under full moons
people connect that to the pool of tides
and it's true
we are very used to the ocean being
deformed
and the water level changing due to the
tides depending on the cycles of the
moon
and this also happens in the earth the
earth itself the continents themselves
are deformed because of this rotation of
the moon
the deformation is not large enough to
produce earthquakes and people have
looked at statistics to see
and there has been absolutely no
correlation at all
a lot of the actions that you need to
take to really protect the community and
to protect people
need to be taken years before
the earthquake actually arrives