Page 22 - Fundamentals of Physical Volcanology
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                                                                                       GLOSSARY   xxi


                 volcanic tremor Relatively long-lived and steady  xenolith A fragment of rock accidentally incorpor-
                   seismic activity associated with the flow of  ated into rising magma and brought up from the
                   magma through a volcanic dike or conduit.    interior of the planet.
                 volume-limited Description of a lava flow that  yield strength The stress level that must be
                   ceases to advance because the supply of magma  exceeded before a non-Newtonian fluid will
                   from the vent has ceased.                    begin to deform and flow.
                 welding The development of mechanical strength
                   between hot pyroclasts in close contact causing
                   them to stick together.
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