这是倒装句嘛

是
原来的语序是A volcano called Vesuvius was near the city.
之所以用倒装是因为主语A volcano called Vesuvius 太长，谓语was near the city太短，如果不用倒装的话则会使句子显得不协调，头重脚轻。

不是

是
原来的语序是A volcano called Vesuvius was near the city.
具体来说是完全倒装
地点状语提前，句子完全倒装

楼上说的对，完全倒装，即Near the city was a volcano who was called Vesuvius。如只看Near the city was a volcano就很明显的知道是个完全倒装了，原来的语序是A volcano called Vesuvius was near the city。