How Earthquake occurs and what causes it | Seismic Waves | P and S Waves

00:04:30
https://www.youtube.com/watch?v=uA_OLKfQpYA

Resumen

TLDRThe video discusses earthquakes, focusing on their causes and the types of seismic waves involved. An earthquake is defined as the shaking of the Earth caused by the release of energy, generating waves that travel in all directions. This energy release frequently occurs along fault lines, where stress overcomes friction, and the rocks slide past each other. The epicenter, located on the Earth's surface above the focus, experiences the strongest wave impact. Seismic waves are divided into two main types: body waves, which include P (primary) and S (secondary) waves, and surface waves. Body waves travel through the Earth's interior, with P waves moving faster and through solids and liquids, while S waves travel slower and only through solids. Surface waves travel across the surface and cause significant destruction due to their displacement of rocks and structures. Seismographs are essential tools for recording these waves. Understanding the differences between wave types, their velocities, and interaction with different materials is crucial to comprehending how earthquakes affect the Earth.

Para llevar

  • 🌍 Earthquake is the result of energy release of Earth's interior, causing ground shaking.
  • 🔍 Faults are breaks in crustal rocks, where stresses are released.
  • 🌌 Focus is the origin of the earthquake energy release; epicenter is surface point directly above.
  • 📈 Seismographs record seismic waves from earthquakes.
  • 💥 P waves are fast and travel through solids and liquids, initiating seismic activity.
  • 🌊 S waves move slower, only through solids, and follow P waves.
  • 🚀 Surface waves move along the Earth's surface and are highly destructive.
  • ⚡ Wave velocity varies with material density, changing direction by reflection and refraction.
  • 🔄 Surface waves cause displacements leading to structural damage.
  • 🪨 Seismic activity provides insights into the Earth's interior structure.

Cronología

  • 00:00:00 - 00:04:30

    Seismic activity provides insights into Earth's interior. An earthquake, defined as Earth's shaking, is caused by energy release that forms waves. A fault is a crustal rock break where movements overcome friction, causing energy release at the focus (hypocenter), with waves reaching the surface at the epicenter. Earthquakes occur in the lithosphere (up to 200km deep). Seismographs record wave patterns, comprising body waves (traveling through Earth) and surface waves (less dense surface slows waves). Body waves include primary (P waves) and secondary (S waves), traveling differently through Earth. Surface waves, recorded last, cause more destruction on the Earth's surface.

Mapa mental

Vídeo de preguntas y respuestas

  • What causes an earthquake?

    An earthquake is caused by the release of energy due to movement along a fault line, generating seismic waves.

  • What is the difference between the focus and epicenter?

    The focus is the point where energy is released underground, while the epicenter is the point on the surface directly above the focus.

  • What are body waves?

    Body waves travel through the interior of the Earth and are composed of P (primary) and S (secondary) waves.

  • How do P and S waves differ?

    P waves are fast-moving and can travel through solids and liquids, while S waves are slower and only move through solids.

  • What are surface waves?

    Surface waves travel across the Earth's surface and are typically more destructive than body waves.

  • How does wave velocity change with material density?

    Wave velocity increases with higher material density and waves change direction when encountering materials of different densities.

  • What instrument records seismic waves?

    A seismograph is used to record seismic waves reaching the Earth's surface.

  • Where do natural earthquakes occur?

    Natural earthquakes occur in the lithosphere, up to 200 kilometers below the Earth's surface.

  • How do seismic waves create faults?

    As seismic waves reach lower density materials near the surface, they can slow down, leaving faults behind.

  • What makes surface waves more destructive?

    Surface waves displace rocks and cause the collapse of structures, making them more destructive.

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  • 00:00:00
    Seesmic activity is also one of the most
  • 00:00:02
    important sources of information about
  • 00:00:04
    the interior of the earth in this video
  • 00:00:07
    we're going to read about the
  • 00:00:08
    earthquakes so what is an earthquake
  • 00:00:10
    it simply means shaking of the earth it
  • 00:00:13
    is caused due to release of energy which
  • 00:00:16
    generates waves that travel in all
  • 00:00:18
    directions now the question is why does
  • 00:00:21
    the earth shake to understand that you
  • 00:00:24
    will have to look at this picture this
  • 00:00:26
    is a fault a fault is a sharp break in
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    the crustal rocks rocks near a fault
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    tend to move in opposite directions that
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    creates friction but at some point of
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    time their movements overcome the
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    friction as a result they slide past one
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    another this causes the release of
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    energy and the energy waves travel in
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    all directions the point where the
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    energy is released is called the focus
  • 00:00:51
    of an earthquake or there is also a term
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    given to it called the hypocenter the
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    energy waves traveling in different
  • 00:00:58
    direction reach the surface the point on
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    the surface nearest to the focus is
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    called epicenter this place is the first
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    one to experience the waves all natural
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    earthquakes take place in the
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    lithosphere the lithosphere refers to
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    the portion of depth up to 200 kilometer
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    from the surface of the earth an
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    instrument called seismograph records
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    the waves reaching the surface the waves
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    look something like this the curve shows
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    three distinct sections each
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    representing different types of wave
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    patterns we'll get back to this pattern
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    in a moment earthquake waves are
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    basically of two types body waves and
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    surface waves I need you to understand
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    the term body waves sounds a little
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    larger within the body right so the body
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    waves are generated due to the release
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    of energy at the focus that is the
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    epicenter and moves in all direction
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    traveling through the body of the Earth
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    you know it travels internally within
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    the Earth's surface and moves the
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    interior of the earth that's why it is
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    referred to as body waves because it is
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    traveling through the body of the earth
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    like a tremor now it is obvious that
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    when these body waves move towards the
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    surface they will come in contact with
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    the surface rocks and
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    like new set of waves these are called
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    surface waves now the velocity of waves
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    changes as they travel through materials
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    with different densities and we know
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    that the materials with higher density
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    reside downwards
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    therefore the denser the material the
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    higher is the velocity the direction
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    also changes as they reflect or refract
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    when coming across materials with
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    different densities that's why when the
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    Seesmic waves reach towards the surface
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    of Earth they're the materials are of
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    lower density and that slows down the
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    intensity of the waves leaving behind a
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    fault now going back to the picture that
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    I showed you so if you look at this
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    picture there are two types of body
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    waves they are called P and S waves so
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    the letter P n S stands for primary and
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    secondary now you can relate when I say
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    primary they are the first one that gets
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    recorded on a seismograph the instrument
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    and then comes the secondary wave you
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    can look at this illustration to
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    understand how these wave looks the P
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    wave that is the primary or pressure
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    wave is a pulse of energy that travels
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    quickly through the Earth's solid
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    materials as well as liquids it forces
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    the ground to move backward and forward
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    as it gets compressed and expanded the S
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    wave that is the secondary or shear wave
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    follows most slowly with a swaying
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    rolling motion that shakes the ground
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    back and forth perpendicular to the
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    direction of the wave if at all the
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    concept of P and S wave isn't clear to
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    you I recommend that you watch this
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    video by dr. Keith Miller where he
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    physically demonstrates bns Seesmic
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    waves the video by him is extremely
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    helpful I'll link the video in the
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    description and you can go and have a
  • 00:03:52
    look at it now going back to this
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    picture after body wave that is P n S
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    waves comes these surface waves these
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    surface waves are the last to report on
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    seismograph they look something like
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    this this wave spreads across the
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    surface of the earth these waves are
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    also more destructive and damaging they
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    cause displacement of rocks and hence
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    the collapse of structures occurs if you
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    want to see more of such education
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    content make sure you subscribed by
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    video comes thanks for watching I'll see
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    [Music]
Etiquetas
  • Earthquakes
  • Seismic Waves
  • Fault Lines
  • P and S Waves
  • Seismograph
  • Lithosphere
  • Body Waves
  • Surface Waves