Part I: Tracking Earthquakes

Tracking Earthquakes and Volcanoes using Google Earth

Part I: Tracking Earthquakes

Oceanic-oceanic plate boundary

  • Magnitude: 4.6
  • Location: 15.441°S 167.557°E, 27 miles ENE of Luganville, Vanuatu
  • Date: 08-19-2014
  • Time: 08:05:05 UTC
  • Depth: 92.6 mi
  • I believe that this earthquake, located in the eastern margin of the Australian plate, occurred here because the Pacific Plate subducts beneath the Australia plate at the Tonga and Kermadec trenches as it moves to the west. This particular subduction zone is one of the most active seismic areas of the world. According to USGS the, “Australia-Pacific convergence rates increase northward from 60 mm/yr at the southern Kermadec trench to 90 mm/yr at the northern Tonga trench.”

Please click on the link below for greater detail from the U.S. Geological Survey (USGS) of this specific earthquake.

http://comcat.cr.usgs.gov/earthquakes/eventpage/usb000s437#summary

Oceanic-oceanic

Oceanic-continental plate boundary

  • Magnitude: 4.3
  • Location:  21.802°S 70.129°W, 20 miles NNE of Tocopillo, Chile
  • Date: 08-23-2014
  • Time: 03:44:59 UTC
  • Depth: 40.3 miles
  • I believe that this earthquake, along with many other earthquakes that occurred from August 19, 2014 to August 24, 2014, do so because the denser Nazca plate moves under the South American plate as they collide together. At this particular convergent boundary, over time the subduction process has created the Andes Mountains during the uplifting process and continues to uplift the mountain range. According to USGS, “Relative to a fixed South America plate, the Nazca plate moves slightly north of eastwards at a rate varying from approximately 80 mm/yr in the south to approximately 65 mm/yr in the north.”

Please click on the link below for greater detail from the U.S. Geological Survey (USGS) of this specific earthquake.

http://earthquake.usgs.gov/earthquakes/eventpage/usb000s5li

Oceanic-continental boundary

Continental-continental plate boundary

  • Magnitude: 4.9
  • Location: 32.329°N 76.427°E, 8 miles NE of Dharmasala, India
  • Date: 08-21-2014
  • Time: 08:11:18 UTC
  • Depth: 6.2 miles
  • I believe that this earthquake occurred because the India plate is colliding with the Eurasian plate at a rate of 40-50 mm/year, and as the India plate thrusts under the Eurasian plate, it creates many shallow-focus earthquakes which make this region quite seismically hazardous. A shallow-focus earthquake is a type of earthquake that originates within 45 miles of the Earth’s outer surface. This earthquake occurred in the foothills south of the Zaskar Range, which is a group of mountains in the Himalayas. Today, the Himalayas continue to rise by more than 1 cm per year as India continues to move northwards literally into Asia.

Please click on the link below for greater detail from the U.S. Geological Survey (USGS) of this specific earthquake.

http://comcat.cr.usgs.gov/earthquakes/eventpage/usb000s4v3#summary

Continental-continental

Divergent plate boundary

  • Magnitude: 4.7
  • Location: 64.751°N 17.376°W, 68 miles SSE of Akureyrum, Iceland
  • Date: 08-23-2014
  • Time: 18:33:07 UTC
  • Depth: 4.9 miles
  • I believe that this earthquake occurred because it was located just west of the Mid-Atlantic Ridge in Iceland. The Mid-Atlantic ridge is a mid-ocean ridge, a divergent boundary located on the floor of the Atlantic ocean, and it is a part of the longest mountain range on Earth. That said, the island of Iceland (also known as the Reykjanes Ridge) is a portion of the ridge that actually has enough elevation so that it rises above sea level—very special indeed. This particular section of the ridge Where this earthquake occurred, the North American and Eurasian plates are moving in opposing directions. As these two plates move away from each other, they create earthquakes, volcanoes, and seafloor spreading. Although the Mid-Atlantic Ridge is mostly an underwater feature, portions of it have enough elevation to extend above sea level.

Please click on the link below for greater detail from the U.S. Geological Survey (USGS) of this specific earthquake.

http://comcat.cr.usgs.gov/earthquakes/eventpage/usb000s5q5#summary

Divergent boundary

Transform plate boundary

  • Magnitude: 6.0
  • Location: 38.215°N 122.312°W, 4 miles NW of American Canyon, California, United States (or 6 miles SSW of Napa, California, United States)
  • Date: 08-24-2014
  • Time: 10:20:44 UTC
  • Depth: 7 miles
  • I believe that this earthquake occurred because its epicenter was on a transform boundary between the Pacific and North American plates.  A transform fault is a type of fault in which two tectonic plates slide past one another. This earthquake was located between two major strike-slip fault systems, the Hayward-Rodgers Creek Fault system (4 miles west of the epicenter) and the Concord-Green Valley Fault system (7 miles east of the epicenter), which are a part of the larger San Andreas Fault system. According to the USGS, “the 1999 Working Group on California Earthquake Probabilities (WG99, 1999) concluded that the Hayward-Rodgers Creek Fault system has a 32 percent probability of generating a large earthquake (M6.7 to 7.4) by the year 2030, and the Concord-Green Valley Fault system has a 6 percent chance of generating a large earthquake (M≥6.7) in the same time period.”

Please click on the link below for greater detail from the U.S. Geological Survey (USGS) of this specific earthquake.

http://comcat.cr.usgs.gov/earthquakes/eventpage/nc72282711#summary

Oceanic-continental

To continue reading about plate tectonics, take a look at how we Identify Volcanoes.

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