Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
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Question: The height of the wave is used to determine the magnitude of an earthquake.

Answer: What measurement of the wave is used to determine the magnitude of an earthquake?


Question: Sodium-potassium pumps help nerve cells establish a voltage across their plasma membranes.

Answer: Sodium-potassium pumps help nerve cells establish a voltage across their what?


Question: When magma heats groundwater, it may come to the surface as a hot spring or a geyser.

Answer:
When magma heats groundwater, it may come to the surface as a hot spring or a what?