Question: seismic waves which travel only through the outer layer of the earth are called
[{'answer': 'Rayleigh waves', 'provenance': [{'wikipedia_id': '89830', 'title': 'Seismic wave', 'start_paragraph_id': 18, 'start_character': 11, 'end_paragraph_id': 18, 'end_character': 25, 'bleu_score': 1.0, 'section': 'Section::::Types.:Surface waves.\n'}]}, {'provenance': [{'wikipedia_id': '89830', 'title': 'Seismic wave', 'start_paragraph_id': 19, 'start_character': 0, 'end_paragraph_id': 19, 'end_character': 711, 'bleu_score': 0.9622032542074631, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 893076029893320105}, 'section': 'Section::::Types.:Surface waves.:Rayleigh waves.\n'}]}]