Which option best describes the direction of the eruption of Mount St. Helens and the cause of this action, according to Figure 15.24 in your textbook?
A) Magma pressure built up and caused a vertical eruption of magma and ash.
B) A rock slide released pressure on the magma, causing a horizontal eruption.
C) An earthquake sheared off part of the mountain, causing a horizontal eruption.
D) An earthquake opened a vent in the top of the mountain, releasing pressure on the magma and causing a vertical eruption.
Answer: B
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