southern california is at great risk for a major earthquake.
the most famous earthquake to happen in california is the san francisco earthquake of 1906. this earthquake is now estimated to have about 7.8 on the richter scale, causing extensive damage to the city. however, an even more intense earthquake that occurred about 50 years before has scientists more worried about a recurrence. the earthquake occurred along a fault line that is known to have a 150-year cycle of activity. this means that the timing is right for the return of the 8-point earthquake that devastated settlements all across southern california in the 19th century. there are growingconcerns about whether the state is ready for such a catastrophe.

안녕하세요,,
밑줄 쳐진 부분의 문장구성이 궁금합니다.
해석은 [그러나 과학자이 더 우려하느 점은 그보다 50년 앞서 발생했던 훨씬 더 강력한 지진이 재발생 하는 것이다] 라고 나와있어요.