Earthquakes and Earth’s Interior - The Changing Earth: Exploring Geology and Evolution - page 200

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Figure 8.11 Relationship between Intensity and Geology for the 1906 San Francisco Earthquake A
close correlation exists between the geology of the San Francisco area and intensity during the 1906
earthquake. Areas underlain by bedrock correspond to the lowest-intensity values, followed by areas
underlain by thin alluvium (sediment) and thick alluvium. Bay mud, artifi cial fi ll, or both lie beneath the
areas shaken most violently.

San
Francisco
Bay

San
Francisco
Bay

16th St. 16th St.

Bay mud (in places covered
by artificial fill as of 1906)

Pacific
Ocean

Pacific
Ocean

Army St. Army St.

Alluvium (>30 m thick)

Alluvium (<30 m thick)

Bedrock

0 1 2 3

km

Geology of the San Francisco area.

a

San
Francisco
Bay

16th St.

Very violent

Pacific
Ocean

Violent

Army St.

Very strong

Strong

Weak

0 1 2 3

km

Intensity of ground shaking in the San Francisco area during the 1906 earthquake.

b