In this activity, students will use a geologic map of the La
Crescenta area and slope inclination data, which are derived from the
topographic map and their topographic model, to determine the
possibility of earthquake-induced landslides in the region.
Each group of students will need:
- Geologic map of the Sierra Madre Fault Zone (Student Packet page 8),
- Topographic map (Student Packet page 7) and student-made topographic model,
- Table: Geologic environments likely to produce
earthquake-induced landslides in the Los Angeles region (Student Packet
page 6) (adapted from USGS Professional Paper 1360), and
- Table: Standard size classes of sediment.
students with copies of the materials listed above. Briefly explain to
students what kind of information each of the materials (tables, model,
maps) contains. For example, explain to students that a geologic map
shows what materials are exposed at the surface.
- Have students study the geologic map and the two tables. Ask
students to locate the geologic environments listed in the table on the
- Discuss the sediment-size table with the class. Explain that
the table shows how geologists classify large and small sediments.
Consider bringing in samples of the smallest sediments and creating
mock pebbles, cobbles, and boulders out of wadded newspaper or
paper-filled trash bags.
- Have students use the tables, geologic map, and
topographical model to answer the following questions about slope,
geologic materials, and the risk of earthquake-induced landslide: Where
is the landslide hazard the lowest? Where is the hazard the highest?
What kinds of landslides are likely to occur in this region?
- Have students mark the topographic map "Highest Landslide
Risk," etc., as they answer these questions in Step 4. 6. Present
students with the following scenario: It's February 1998. There's been
an earthquake along the Sierra Madre Fault, magnitude 7.0 on the
Richter scale. Have students find the Sierra Madre Fault on the
geologic map. Then ask them to identify the locations where
earthquake-induced landslides are likely to occur.
- To connect this extended map interpretation activity to the
Focus Question, ask students, "Based on the information in the geologic
environments table, what can you predict about the potential for
earthquake-induced landslides in the La Crescenta area?"
- Students could predict what would happen in the La Crescenta region if an earthquake occurred right after a heavy rain.
- Students could develop a susceptibility map and use it to answer the Focus Question in their final presentations.
map of model area (Activity 2). Create your own landslide hazard map.
Use this topographic map to mark locations where you believe landslide
risk is high or low.|