Sent to you by Zeeshan via Google Reader:
via Slate Magazine by Brian Palmer on 1/14/10The 7.0-magnitude earthquake that rocked Haiti on Tuesday was the most powerful in the region for more than 100 years. A 7.2-magnitude quake struck the island in 1887, and another, from 1751, registered a 7.3. Wait a second—modern seismography dates back only to the late 19th century, and the Richter scale is just 75 years old. How do seismologists know the strength of a 1751 earthquake?
Earthquake - Richter magnitude scale - Haiti - Seismology - Earth Sciences