翻译：
被地理学家称作“热点”的孤立的火山活动区域,有100多个零零星星地分布在地球.
分析：这是倒装句,正常顺序应为：
More than 100 small regions of isolated volcanic activity,known to geologists as hot spots,are scattered around the globe.
这里Known是know的过去分词,具被动语义,意思是：对地理学家们,被理解为“热点”.原句可以修改成：
More than 100 small regions of isolated volcanic activity,which is known to geologists as hot spots,are scattered around the globe.