The major similarity among the geologic hazards (as opposed to climatic hazards) that face people in the Pacific Realm is that they are typically caused by plate tectonics in some way. The major difference is that they can be very different in terms of how widespread their impact is from the place where the hazard is caused.
There are three major kinds of geologic hazards faced by people in this realm. These are volcanic eruptions, earthquakes, and tsunamis. All of these are caused by plate tectonics. Earthquakes are caused by tensions that arise when plates move relative to one another. The volcanoes of the Pacific Realm are generally created by the subduction of one plate under another. Tsunamis are typically caused by the shaking of the earth that happens in earthquakes or volcanic eruptions. Thus, all of the geologic hazards in this realm have a common cause.
There are, however, differences in the extent of these hazards. The effects of volcanic eruptions are typically limited to the area near the volcano. There can be inconveniences like ash falling far from the volcano, but the major damage from a volcano typically happens very near to the volcano. Earthquakes can do damage further away from their epicenters. Earthquakes cause shaking over a relatively large area. Tsunamis can cause major damage far from where they are caused. The waves travel through the ocean and have an impact far from the earthquake or volcano that caused them.