A'a is associated with effusive (quiet) eruptions.
The differences are that Pahoehoe produces fast moving lava; Aa produces slower moving lava. The kind of eruption that produces these types of lava is a quiet eruption.
Quiet eruptions
Pahoehoe and AA lava are produced by quiet eruptions. This means that instead of a blast or explosion, the lava just flows out of the volcano. Pahoehoe lava is hot and flows quickly. AA lava is cooler in temperature and doesn't flow as quickly.
It produces a quiet eruption.
Pahoehoe is hot, fast-moving lava that has a low viscosity. AA lava has a cooler temperature and moves more slowly. Quiet eruptions are the type that produce these two types of lava.
There are two choices that produce the least phenotypic variation. AA times aa produces only Aa offspring. AA times Aa produces and AA and Aa offspring.
Aa and pahoehoe are both produced from basalt lava eruptions. The difference in the two being a difference in temperature. Pahoehoe is a hotter flow, moving more smoothly before cooling into rope-like structures. Aa is a bit cooler, forming solid chunks, but continuing to move.
During a nonexplosive eruption, lava flows out from the volcano in a slow and steady manner. The lava is typically less viscous, allowing it to flow smoothly and cover greater distances. This type of eruption is characterized by the slow-moving streams of lava that can create new land formations as they cool and solidify.
Pahoehoe comes from an explosive eruption, whereas AA comes from quiet eruptions.
Lava flows of pahoehoe and aa indicate that the eruption was effusive ("quiet") rather than explosive, or only very mildly explosive.
They indicate that an eruption is effusive rather than explosive.
They indicate that an eruption is effusive rather than explosive.