Question: what triggered the may 18 1980 eruption of mount st. helens
[{'answer': 'An earthquake', 'provenance': [{'wikipedia_id': '673671', 'title': '1980 eruption of Mount St. Helens', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 13, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '673671', 'title': '1980 eruption of Mount St. Helens', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 381, 'bleu_score': 0.85229284983615, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 16859165851173619760}, 'section': 'Section::::Abstract.'}]}]