Sci 10 1st quarter

• Taal, Pinatubo and Mayon volcanoes are the familiar volcanoes of the country in terms of their eruptions. They are formed when pieces of earth's crusts called plates smash and buckle up through a process called plate tectonics. Some form mountain ranges or hill ranges arranged in a line and connected by high ground.

  
• Finding the Epicenter


  1. Study the data showing the difference in the arrival time of P-wave and S-wave on three seismic recording stations

  2. Compute the distance of the epicenter from each of the stations using the formula: d = time difference x 100 km

  3. Choose one of the recording stations and measure the computed distance on the scale (the scale of the map is 1 cm: 100 km). Set your compass for that computed distance. Center your compass on the station you have chosen. Draw a circle.

  4. Repeat the previous step for the rest of the stations. You should get three circles that intersect or nearly intersect at a point. This intersection is the epicenter.
• Determining the Arrival Times between P-wave and S-wave


  1. Line up the ruler or a piece of scrap paper vertically on the epicenter distance given.

  2. Mark the locations where the P-wave and S-wave intersect your ruler or scrap paper.

  3. Line up the ruler or scrap paper on the y-axis with one point on the 0 minute mark.

  4. The second mark will indicate the difference in arrival time.
• Seismic waves are the waves of energy caused by the sudden breaking of rock within the earth or an explosion. They are the energy that travels through the earth and is recorded on seismographs.
• Seismologists use triangulation to find the epicenter of an earthquake. When seismic data is collected from at least three different locations, it can be used to determine the epicenter by where it intersects. Every earthquake is recorded on numerous seismographs located in different directions. Each seismograph records the times when the first (P waves) and second (S waves) seismic waves arrive. From these, seismologist can determine how fast the waves are traveling. Knowing this helps them calculate the distance from the epicenter to each seismograph.
• Seismologists use triangulation to find the epicenter of an earthquake
• Determining earthquake epicenter


  1. Collect seismic data from at least three different locations

  2. Use the intersection of the data to determine the epicenter
• P waves


  First seismic waves
• S waves


  Second seismic waves
• Determining distance to epicenter


  1. Record arrival times of P and S waves

  2. Calculate wave travel speed

  3. Use wave speed to calculate distance to epicenter
• Distance-time graph


  • Gradient of the line equals the speed of the object
  • Steeper line means faster object
• If an object moves along a straight line, the distance travelled can be represented by a distance-time graph
• Observable/physical characteristics


  • Earthquake epicenter
  • Active volcano
  • Mountain range

  
• Most active volcanoes, earthquake epicenters, and mountain ranges are found in the Pacific Ring of Fire or in the Pacific Ocean basin

  
• Earthquake


  Shaking of the earth's surface that often causes great damage
• Epicenter


  Part of the earth's surface directly above where the earthquake starts
• Volcano


  Mountain with a hole in the top or side that sends out rocks, ash, lava, etc.

  
• Mountain range


  Succession of many closely spaced mountains covering a particular portion of earth

  
• Convergent boundary


  Boundary where two plates move toward each other, causing one plate to subduct beneath the other
• Divergent boundary


  Boundary where the crustal plates are moving apart
• Transform fault boundary


  Boundary produced when two plates slide past each other
• Faults are cracks in the lithosphere caused by the stresses created as sections of a plate (or two plates) move in different directions
• Types of plate boundaries


  • Convergent (continental-continental, oceanic-oceanic, oceanic-continental)
  • Divergent
  • Transform
• Convergent boundaries can form mountain ranges, volcanoes, and earthquake belts
• Divergent boundaries form mid-ocean ridges and rift valleys
• Transform boundaries are locations where two plates slide past one another
• Most transform faults are found in the ocean basin and connect offsets in the mid-ocean ridges
• Plate movement


  1. Convection currents in the mantle

  2. Ridge push

  3. Slab pull
• Convection currents


  Hot, less dense rising material spreads out, causing upward and sideward forces that lift and split the lithosphere at divergent plate boundaries
• Convection currents


  Rotate slowly, dragging the tectonic plates along the tectonic boundaries, pushing each other, sliding past each other and drifting away from each other
• Ridge push


  As the older seafloor sinks, the weight of the uplifted ridge pushes the oceanic crust toward the trench at the subduction zone
• Slab pull


  The weight of the subducting plate pulls the trailing slab into the subduction zone
• Tectonic activities at the surface like volcanic eruptions and earthquakes are inevitable due to the processes happening inside the Earth
• Plate tectonics enable complex chemistry and recycle substances like carbon dioxide, which acts as a thermostat and keeps Earth balmy
• A massive impact may have happened to our planet that may have made the Earth a friendlier place for life because it corresponds with this planet's establishment of plate tectonics
• In 1912, Alfred Wegener (pronounced as vey-guh-nuhr), a German meteorologist, proposed a theory that about 200 million years ago, the continents were once one large landmass. He called this landmass Pangaea, a Greek word which means "All Earth." This Pangaea started to break into two smaller supercontinent called Laurasia and Gondwanaland during the Jurassic Period. These smaller supercontinents broke into the continents and these continents separated and drifted apart since then.
• Wegener searched for evidences to support his claim. He noticed the fit of the edges of the continents on the opposite sides of the South Atlantic. His evidence to the Continental Drift Theory includes the distribution of fossils in different continents, rock features, and ancient climates.
• SONAR (Sound Navigation and Ranging)


  A device that bounces sound waves off underwater objects and then records the echoes of these sound waves. It allowed scientist to map the mid-ocean ridges.
• Arthur Holmes (1929)


  A British geologist who suggested that thermal convection currents in the mantle were the force moving the continents.
• Ship Atlantis (1931-1966)


  The first ship built specifically for marine biology, geology, and oceanographic. The first Woods Hole Oceanographic Institution (WHOI) research ship.