Sentence: Scientists have predicted that a large earthquake will hit western Japan before the end of the decade.
The word "decade" has the meaning of "a period of ten years", so does the sentence mean that in less than 10 years there might be an earthquake? My teacher interpreted this way, but I don't think so. When we use the word decade in these kind of cases, doesn't it mean like the year 2000, 2010, 2020, 2030, and so on? Say we are in 2017, and what the sentence is saying that before 2020, there might be an earthquake. Which interpretation is correct?