Interpreting the Distribution of Earthquakes (Grades 7-8)

The movement of magma can be tracked by mapping the distribution of earthquakes. Earthquakes can precede an eruption by years, months, days, and, in a few cases, hours. Activity 14 shows the migration of epicenters preceding and accompanying dike emplacement and the onset of the current eruption of Kilauea Volcano in January 1983. Students must interpret the distribution of the earthquakes to answer the following questions.

Click here for a copy of Activity 6.

  1. Where did the seismicity begin?
    Seismicity began in the upper east rift zone near Makaopuhi Crater.

  2. In what direction did the seismicity migrate?
    Seismicity migrated down rift to the east.

  3. How do you interpret the seismic patterns for 00 hours on January 1 to 00 hours on January 3?
    The pattern suggests intrusion and migration of a dike of magma to the east.

  4. How do you interpret the seismic patterns for 00 hours on January 3 to 00 hours on January 8?
    The seismic patterns are due to continued intrusion of magma and the start of the eruption.

  5. When does seismicity begin at the summit?
    After the onset of the eruption on January 3.

  6. How do you interpret the seismicity at the summit?
    The seismicity at the summit suggests deflation and the migration of magma down the rift, probably due to a decrease in pressure by the eruption.

  7. Based on the data presented in the graphs, outline the geologic events preceding and accompanying the onset of the current eruption.

Other Activities To VolcanoWorld