WORLD

The deadliest earthquake of 2017 struck Iran and Iraq late Sunday evening, rocking the two countries and killing more than 400 people. (National Geographic)

Use our video to better understand earthquakes.

Teachers, scroll down for a quick list of key resources in our Teachers’ Toolkit, including today’s simple MapMaker Interactive map.

Discussion Ideas

• In our video “Earthquakes 101,” we learn that most earthquakes are caused by the movement of tectonic plates far below Earth’s surface. What tectonic plates were interacting in the earthquake that struck Iran? Take a look at today’s simple MapMaker Interactive map for some help.
  • The Arabian and Eurasian plates were interacting.

• How were the plates interacting? Take a look at the classic Nat Geo map of “Earth’s Dynamic Crust” for examples of different types of tectonic activity.
  • According to the USGS, “At the location of this earthquake, the Arabia plate is moving towards the north with respect to Eurasia at a rate of about 26 mm/yr. The two plates converge along a northwest-striking plate boundary in the general vicinity of this earthquake, driving the uplift of the Zagros mountains in Iran.”
    • Our map key calls this “Collision” interaction nothing less than “the greatest mountain-making process on Earth.”
    • Specifically, the Iran quake was the result of “oblique thrust faulting” a complex process that incorporates significant strike-slip faulting (horizontal movement) and normal or reverse faulting (vertical movement, also called dip-slip faulting). Watch this video from the good folks at the Incorporated Research Institutions for Seismology for help.

• The Iran-Iraq quake is described as having a magnitude of about 7.3. What is magnitude? Is 7.3 a high magnitude?
  • Magnitude is a number that describes the intensity or size of an earthquake. Our “Earthquakes 101” video talks about the Richter scale of magnitude, but seismologists are far more likely to use the moment magnitude scale (MMS or simply M).
  • A 7.3 quake has a very high magnitude. Seismologists qualify this as a major earthquake. Only about 20 quakes of 7.0-7.9 occur each year.

• The Iran-Iraq quake is described as having a focal depth of about 25 kilometers (15.5 miles) at its epicenter. What is focal depth? What is an epicenter? Is 25 kilometers a deep or shallow focal depth?
  • The focal depth of an earthquake is how far below the surface of an earthquake’s epicenter the actual rupture, slip, or dip took place.
  • The USGS makes sure to note that the quake did not have a pinpoint epicenter. Instead, they describe the quake as a wide-ranging event. “Oblique-thrust-faulting events of the size of the November 12th, 2017, earthquake are typically about 65×25 kilometers (40×16 miles).”
  • Earthquakes can take place anywhere between one and 700 kilometers below Earth’s surface, so 25 kilometers is a pretty shallow depth.

TEACHERS’ TOOLKIT

Nat Geo: Pictures Reveal Iran and Iraq Earthquake, the Deadliest of 2017 (article)

Nat Geo: Deadly Quake Strikes Iran-Iraq Border (interactive map)

USGS: M 7.3 – 32km S of Halabjah, Iraq (article and maps)

Nat Geo: Earthquakes 101 (video)

Nat Geo: Earth’s Dynamic Crust (hi-res map)