How can volcanic activity occur so far from a plate boundary?

火山活动是如何在离板块边界那么远的地方发生的呢？

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The boundary between the Australia Plate and the Sunda Plate is a thick black line.

澳大利亚版块与巽他板块的板块边界在图上以一条粗而黑的线条表示。

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Mantle material can sink at a plate boundary, and then flow back upward farther away, pushing on the crust - a process called small scale convection.

地幔，这种物质可以在板块边界处下沉，然后向上回流到较远的地方，再与地壳相碰撞——这个过程被称为小规模的对流。

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Instead of occurring at a plate boundary along an area called a subduction zone, where one tectonic plate is diving beneath another, this earthquake occurred in the middle of an oceanic plate, where the faults in the crust essentially moved from side to side instead of up and down.

MSN: Why this Indonesia quake didn't spark a monster tsunami

The Australian plate borders the Pacific plate to the East (the Samoan quake occurred along this boundary), while on the Western side, it borders the Eurasian plate (where the Indonesia quake occurred).

CNN: Two quakes in the same region in a day - coincidence?