Scattered around the globe are more than 100 small regions of isolated volcanic activity known to geologists as hot spots.

【翻译】

1. 散落在地球上的是，被地质学家称为热点的100多个互不相连的小型火山活跃区。

（这是直译）

2. 散落在地球上的100多个互不相连的小型火山活跃区，被地质学家称为热点。

（这是意译）

【分析】这是一个特殊倒装句。正常语序是一个被动句：

1. More than 100 small regions of isolated volcanic activity known to geologists as hot spots are scattered around the globe.

句子成分划分：More than 100 small regions of isolated volcanic activity （主语）known to geologists as hot spots （定语）are scattered （谓语）around the globe（地点状语）.

regions of isolated volcanic activity：孤立的（互不相连的）火山活跃区

2. known to geologists as hot spots 作定语，修饰regions。意为“被地质学家称为热点的（火山活跃区）”。

【结构详析】

1. known as...：以......为人所知；以......著称；被称为

2. known to...：为某人所知

3. known to sb. as sth. ：作为某物为某人所知；被某人称为某物

举例说明：

Mr. Johnson was known to us as a walking dictionary. 
约翰逊先生被我们称作一本活字典。
直译：约翰逊先生以活字典的身份为我们所知。