WORLD

Major Earthquake Strikes Iran
Iran has been struck by its most powerful earthquake for more than 50 years, with tremors felt across Pakistan, India, and the Middle East. The 7.8-magnitude quake struck the city of Khash.

Discussion Ideas:

• Walk through our “Forces of Nature” interactive, which explains what earthquakes are, where they occur, and how they develop. Choose the earthquake layer—the far right icon in “Choose a Force.” Have students read through the first “Case Study” in the interactive, which profiles the 2003 earthquake that struck Bam, Iran. Can students identify some similarities and differences between the Bam earthquake and the Khash earthquake?
  • Similarities:
    • Both quakes struck southeastern Iran.
  • Differences:
    • The Bam quake struck a more populated area, and had a higher casualty (death and injury) count than the Khash quake (at least at this reporting).
    • The Bam quake had a much shallower focal depth. This means it struck close to the surface, which often leads to greater damage. The “Forces of Nature” case study says the Bam quake struck just below the surface, while the BBC article says the Khash quake had a focal depth of 95 kilometers (59 miles). (The al-Jazeera video, quoting USGS sources, puts the focal depth slightly shallower, at 82 kilometers (51 miles) below the surface of the Earth.)
• Like all earthquakes, the Khash quake was caused by plate tectonics: the movement of the large, rocky plates that make up the Earth’s lithosphere (the upper portion of the Earth’s mantle and crust). Look at the “Plate Tectonics” layer of our MapMaker Interactive. Can students identify the tectonic plates that meet in southeastern Iran?
  • The Arabian and Eurasian plates meet in southern Iran, while the Indian plate meets both just to Iran’s east, in Pakistan and the Arabian Sea.
• Refer back to our “Forces of Nature” interactive. Consider the four different types of faults explained there. (Types of Faults are in the “Lab” tab, in the fourth slide.) What type of fault do students think exists between the Arabian and Eurasian plates in southeastern Iran?
  • It’s a reverse fault. This terrific article explains Iran’s complex tectonic activity, mostly driven by the Arabian plate shifting northward. In Iran’s southeast, the Arabian plate is being subducted, or crushed beneath the massive Eurasian plate, as it moves north. The region is called the Makran subduction zone. (A different type of reverse fault extends along Iran’s western border, where the northward-moving Arabian plate crashes into the Eurasian plate to form the Zagros Mountain range.)
• Look at the “Earthquakes” layer of our MapMaker Interactive, focused on Iran. Have many earthquakes been reported in the southeastern part of the country? Can students think of reasons why or why not?
  • Not a lot of earthquakes have been recorded in southeastern Iran, considering the tectonic activity of the region. (Although another occurred just last week!) This is probably a result of inadequate reporting, not a lack of earthquakes. Sistan Baluchistan, the province where the Khash quake took place, is one of the least-developed and least-populated regions in Iran. It lacks sophisticated geological reporting equipment, facilities, and infrastructure. Tremors in the region may go unreported for years. As Imtiaz Tyab, the al-Jazeera reporter, acknowledges in the video, “Because it’s such a remote area, it’s quite difficult to get information from there.”