Porphy no Nagai Tabi

both stories about siblings brother and sister survived an earth quick  

While any two World Masterpiece Theater series could be fairly compared, Perrine and Porfy happen to be two of the closest to each other in a myriad of ways. Both incorporate a strong theme of travel, which shares many specific elements that would descend into spoiler territory if described further. Both are very slowly paced; much of the early action is episodic to the point where many viewers find both series dull. Finally, despite being made over thirty years apart from each other, their art styles are quite similar, with rather flat characters and extra attention to background detail. 

Both Animes are about a boy, who is searching for one of his family members. While Marco is searching for his mother in argentinia, Porphy is searching for his little sister in west europe.