Why do seismic waves travel a curving path through the Earth? Refraction For background on this animation series, download Background from the Resources box.Animations are available for preview in embedded YouTube. To download, right click the 'Quicktime Animation' link and choose 'Save Target As' (PC) or 'Download Linked File' (Mac).Send us feedback. Travel times through different media This animation shows what happens to seismic waves as they encounter a boundary between a slower and faster layer in the Earth with introduction to Snell’s Law. Quicktime Animation (4 MB) Seismic Sprint—race to the seismometer The animation on the left describes the relative speeds of the direct, critically refracted and head waves. Quicktime Animation (1 MB) Seismic Sprint—graphing the seismograms Using the same seismic ray paths, the animation below adds a graph to see how data recorded show the distance transition of first arrival wave paths. Quicktime Animation (3 MB) Direct ray races 5 different refracted rays Quicktime Animation (2 MB) Quicktime Animation (3 MB)
QuakeFeed iPhone App Teaching_strategies Natural Hazards• ELI Natural Hazards category Plate tectonicsPlate tectonics - whole concept:-• Partial melting - simple process, huge global impact (ELI+)• Partial melting model and real rock (ELI+)• Plate riding (ELI+)• Plate tectonics through the window (ELI+)• Plate margins and movement by hand Evidence and explanation for the theory:-• Continental jigsaw puzzle (ELI+)• Earth time jigsaw puzzle• Geobattleships (ELI+)• Wegener’s ‘Continental drift’ meets Wilson’s ‘Plate tectonics’ (ELI+)• Did the continents move for you? (ELI+) Mechanism:-• Bouncing, bending, breaking• Mantle plume in a beaker (ELI+)• What drives the plates? Constructive or divergent plate margins:-• Mantle plume in a beaker (ELI+)• Magnetic stripes (ELI+)• Model a spreading ocean offset by transform faults (ELI+)• Continental split - the opening of the Atlantic Ocean Resources• Fracking: Recipe for the perfect fracking fluid• Make your own oil and gas reservoir• Trapped! Volcanoes• Blow up your own volcano!
Earthquakes - Q-files Encyclopedia Many earthquakes take place where one tectonic plate slides down beneath in another in what is called a subduction zone. Shock waves are sent out in all directions when, deep under the ground, the locked plates suddenly "give". A subduction zone How an earthquake happens The outer layer of the Earth is made up of a number of giant slabs, called tectonic plates. P- and S-waves travelling through the Earth's interior Shock waves The sudden jolt of a quake usually lasts no more than a few minutes and may be over in just a few seconds. P-waves (1) squeeze and stretch the rocks. P-waves (1) and S-waves (2) Shock waves radiate from the epicentre like ripples on a pond. There are different types of shock waves. Customers in a cafe experience an earthquake. Effects of a quake The shock waves hurtling through the crust cause the ground to shake. A road cracks open along a fault line, with one side slipping down a few centimetres. A road cracks open along a fault line. Unstable ground After an earthquake
How do P & S waves give evidence for a liquid outer core? Shadow Zones For background on this animation series, download Background from the Resources box.Animations are available for preview in embedded YouTube. To download, right click the 'Quicktime Animation' link and choose 'Save Target As' (PC) or 'Download Linked File' (Mac).Send us feedback. Intro to Shadow Zones The seismic shadows are the effect of seismic waves striking the core-mantle boundary. Quicktime (5.73 MB) Seismic Shadow Zones vs Light Shadows The wave properties of light are used as an analogy to help us understand seismic-wave behavior. Quicktime (9.36 MB) Shadow Zone Rollover Flash interactive rollover shows the different P and S phases and their respective shadow zones. Flash (154 kB) P Phases and the Shadow Zone Animation addresses 5 common variations of P-type seismic body waves. Quicktime (6.31 MB) S Phases and the Shadow Zone Animation addresses 3 common variations of S-type seismic body waves. Quicktime (4.49 MB) Please send feedback to Jenda Johnson.
Plate Tectonics Activities | JOIDES Resolution - Ocean Drilling Research Vessel The first three activitie s below are variations on the theme of ages of the basement rock spreading outward from the mid-Atlantic Ridge as determined by Deep Sea Drilling Project scientists with samples of microfossils taken by RV Glomar Challenger in 1968. 1. The Race Is On… with Seafloor Spreading! As always, you are invited to follow the adventures of the JOIDES Resolution drill ship, where you can join the expeditions, interact with the scientists and search for more about topics like plate tectonics! To search for more resources related to this topic, go to our Educator Resources page.
Earthquakes may reveal new layer of the Earth: the inner inner core Though you may be familiar with the phrase “molten core,” the reality is that Earth’s inner core is actually solid, and it’s the outer core that surrounds this enormous ball of heavy metals which remains liquid. A new study from American and Chinese researchers now posits the existence of an all-new region of the Earth, a distinct core within the inner core — an inner inner core. By studying the propagation of shockwaves from earthquakes around the world, they think they can prove that the iron crystals there are aligned differently than the outer inner core, and that has big implications for our understanding of how the Earth first formed. The solid metal core at the center of the planet formed and cooled to a solid state very (very) slowly. Here’s a simplified look at how researchers interpret seismic wave information. Why would something as small as this matter?
Earthquakes And Tsunamis Almost every year, a large earthquake occurs somewhere in the world and captures the public's attention. Meanwhile, every day thousands of smaller tremors often go unnoticed by most people. Although we usually consider the ground to be solid and stable, the earth is, in fact, constantly shifting under our feet. What causes earthquakes? Earth's crust ranges from 3 to 45 miles deep (5 to 70 kilometers). As they slide past one another, the tectonic plates snag on rough patches of rock. An earthquake occurs when the pressure built up along a fault becomes stronger than the pressure holding the rocks together. Even though the tectonic plates slide at a regular rate over time, the way that faults release stored energy is different with each earthquake, said Shimon Wdowinski, a geophysicist at the University of Miami's Rosentiel School of Marine & Atmospheric Sciences. Tsunamis If the earthquake occurs in the ocean, it can push up powerful waves, known as tsunamis. Measuring earthquakes