Landslide – Portuguese Bend, CA. The Problem 1 placemark flies you to the Portuguese Bend area in California. This region has experienced a massive (and progressive) landslide that has cannibalized the subdivision that once existed on the cliffs overlooking the ocean. How did urbanization likely contribute to cause the mass wasting? You may want to use your textbook. Choose one: a. Vibrations from traffic destabilized the slope. b. Concrete allowed the underlying soil to dry out and lose cohesion. c. Landscape plants (e. g., trees, bushes) disrupted the stability of the soil. d. Water from septic systems, sprinklers, etc., lubricated a layer of bentonite clay that slopes toward the ocean.