Complex sentence: In Rock Creek, tourists camping there were caught off guard by the quake and landslide, which swept them into the creek by causing a seiche which inundated trailers and tents, uprooted trees, and injured one additional person.
Split into simpler sentences: In Rock Creek, tourists camping there were caught off guard by the quake and landslide, which swept them into the creek. The earthquake caused a seiche which inundated trailers and tents, uprooted trees, and injured one additional person.