Horizontal Changes In Distance

As magma accumulates in the summit reservoir, the increase in pressure causes the volcano to inflate. With inflation the distance between two points near the summit will increase. The graph shows data from the summit of Mauna Loa volcano measured using an EDM. The location of the two measuring sites is shown in the inset. Use the graph to answer the following questions.

  1. From 1966 to 1985 did the distance between the two stations increase, decrease, or remain the same? (circle one)

  2. From 1966 to 1974, did the distance between the two stations increase, decrease, or remain the same? (circle one)

  3. What caused the rapid increase in distance in 1975 and 1984?

  4. From late 1975 to early 1984, did the distance between the two stations increase, decrease, or remain the same? (circle one)

  5. After the onset of the eruption in March 1984, did the distance between the two stations increase, decrease, or remain the same? (circle one) What caused this change?