Problem 19 The 1906 earthquake in San Franc... [FREE SOLUTION] (2024)

Short Answer

Earthquake Intensity

The concept of earthquake intensity is key to understanding how different earthquakes affect regions. The Modified Mercalli Intensity (MMI) scale is commonly used to gauge this intensity. Unlike the Richter scale, which measures an earthquake's magnitude, the MMI scale focuses on the effects and damage caused by the quake. This scale ranges from I (barely felt) to XII (total destruction). For instance, the San Francisco earthquake in 1906 with an intensity of X means significant damage and great panic among people. Compare that to the Alaskan earthquake of 1964 with an intensity of XI, which implies even more severe damage and destruction.

Structural Damage

Structural damage during an earthquake varies significantly based on the intensity of the quake. Buildings, bridges, and other structures suffer more severe damage as the intensity increases. On the MMI scale, each increment represents a notable increase in destructive power. For example, at level X, expect heavy damage to well-built structures and severe damage to poorly built ones. At level XI, the damage extends further, causing nearly all buildings to suffer structural failures, if not outright collapse. Hence, the 1964 Alaskan earthquake being rated XI indicates more extensive and severe destruction compared to the 1906 San Francisco earthquake rated X.

Comparative Analysis

When conducting a comparative analysis between two earthquakes, looking at the intensity ratings provides valuable insights into the relative damage caused. The Modified Mercalli Scale allows us to make informed comparisons by translating the seismic activity into observable effects. For instance, by comparing the 1906 and 1964 earthquakes, we see that the latter had a higher intensity rating (XI vs. X). This directly correlates to more extensive structural damage and a broader impact area for the Alaskan earthquake compared to the San Francisco one. Therefore, while the number of fatalities was higher in San Francisco, the MMI rating indicates the overall destructiveness was greater in Alaska.