Given the background: Earthquakes may take place every day near a volcano. But before an eruption, the number and size of earthquakes increases. This is the result of magma pushing upward into the magma chamber. This motion causes stresses on neighboring rock to build up. Eventually the ground shakes. A continuous string of earthquakes may indicate that a volcano is about to erupt. Scientists use seismographs to record the length and strength of each earthquake. and the situation: Pam and Jane were two researchers. Pam studied sedimentary rocks while Jane studied volcanoes and related phenomena, such as earthquakes. Answer the following question: Which researcher didn't observe what happens before a volcanic eruption?
A:
Pam