The 1964 Great Alaska Earthquake is often cited as the second most powerful earthquake ever recorded on Earth.

• A. True
• B. False
• C. Not Enough Data
• D. Depends On The Source

Answer: (A)

Understanding how earthquakes are ranked helps explain this statement. Seismologists use the moment magnitude scale to measure how much energy an quake releases, and the scale is logarithmic, so a small change in magnitude means a large difference in energy.

The 1964 Great Alaska Earthquake, which struck near Prince William Sound, had about magnitude 9.2. That makes it the second-largest earthquake ever recorded with modern instruments, behind the 1960 Valdivia (Chile) earthquake at about magnitude 9.5. While geology provides estimates for some ancient quakes that could have been as large or larger, those are not instrumentally recorded events. So, given recorded data, the Alaska event ranks second globally, with the Chile event ranking first. The earthquake also triggered powerful tsunamis and intense shaking across the Pacific, underscoring why it’s remembered as one of the most significant quakes in history.