Earth's Seismic Waves ESS2.2

Use the resource linked here to help you answer the questions below. Drag the characteristics into the appropriate column. P-waves "Primary" Waves Travels as a longitudinal wave. Particles oscillate back and forth as the wave passes. Travel the fastest and are the first to arrive. Displacement of particles is parallel to the direction the waves travel. S-waves "Secondary" Waves Displacement of the particles is perpendicular to the direction the waves travel. Particles oscillate up and down as the wave passes. Travels as a transverse wave. Slower velocity and arrives second. Type of Wave Definition "Slinky Comparison" Medium Traveled Through Movement Through Material P-waves Longitudinal waves that travel through solids and liquids by compressing and expanding particles in a parallel direction. Rings of the slinky are compressed and then released so that the rings create compressions and rarefractions. Travels through solids and liquids. Particles move parallel to movement of the wave as the wave compresses and expands the particles. S-waves Transverse waves that travel through solids by moving particles perpendicular to the direction of the wave. The end of the slinky is lifted and brought back down to push the transverse wave through the slinky. Can only travel through solids. Particles move perpendicular to the movement of the wave as the wave lifts a section and then releases it. Feeling the ground shake with seismology - how does it works Earthquakes happen when faults slip or magma splits the crust. They send out seismic waves through the Earth just as dropping a pebble into water makes rings of ripples.Seismographs record seismic waves. They contain a weight and a pen attached to a spring (below). The seismograph is bolted to the ground so during an earthquake it moves with the ground, whilst the weight and pen remain still. The pen moves across a rotating paper roll recording the seismic waves. This plot is called a seismogram and is used to understand earthquakes.During an earthquake, seismic waves arrive at the closest seismograph first and later at ones further away. We use this information to locate the earthquake. An example from Afar is shown right. The station at which the seismic waves arrive first must be the closest to the earthquake. We estimate its location, then calculate what the arrival times at the other seismographs would be if this was right. We keep refining the location until it fits the arrival times for all the seismographs. What are seismographs designed to record? Parallel ground motion Vertical ground motion Perpendicular ground motion Horizontal ground motion Select 2 parts of the seismograph that are moved by the vibrating ground. Pen Weight Frame Paper Roll Analyze the paper produced by the seismograph to answer the following questions. Which type of wave affected the seismograph first? p wave s wave surface Which type of wave was measured as the most intense? p wave s wave surface How to Locate the Epicenter of an Earthquake Watch the video to help you answer the questions below. Which type of wave is measured by the station first? p wave s wave Fill in the missing terms to summarize the content of the video. As the waves travel from the epicenter of the earthquake, the distance between p-waves and s-waves increases. This increasing distance can be observed as the waves reach stations that are further away from the epicenter. As the wave travels further from the epicenter, the amplitude on the seismographs decreases in size as energy spreads out. Distance from a single station can be determined, but in order to locate the epicenter, multiple stations must measure distances based on the seismographs. Then overlap the circles to triangulate the location of the epicenter. This procedure can also be used to determine the depth at which the earthquake started. The magnitude of the earthquake depends on the height of the signals that we receive at the different stations. Averaging the amplitudes measured at the different stations gives the magnitude of the earthquake. Read the text and use the image as a reference to help you answer the questions. What are the two main ways geologist study the Earth’s interior? Direct evidence from rock samples Indirect evidence from seismic waves By digging super deep holes and visually peering into the Earth They compare the data collected by space probes to determine the most likely commonality. Fill in the missing words. There are two pieces of information from seismic waves that give geologists clues about the structure of our planet. Geologists can measure the speed of seismic waves as they change mediums deep within the earth. When the wave enters a new medium within the Earth it refracts causing the path of the wave to change as it changes speed. Geologists have found that the paths of seismic waves change when the waves reach specific depths inside the Earth. What can you infer about Earth's structure from this observation? That the Earth stays Solid throughout. That the Earth's interior changes mediums at specific depths. That seismic waves have interference throughout the Earth's interior, therefor unreliable. Anatomy of an Earthquake Use the following links to answer the questions below The focusis the place inside Earth’s crust where an earthquake originates. The point on the Earth’s surface directly above the focus is the epicenter. The lithosphererefers to the crust and upper mantle that make up these plates. Platesare massive rocks that make up the outer layer of the Earth’s surface and whose movement along faults triggers earthquakes. By using information from three seismometers, you can calculate the epicenter - which is where all three distances meet, in a process called triangulation.