[JoeFromSidney]

the number of volcanoes erupting as you read this article is greater than the 20th century’s yearly average

The current number may be greater than the 20th Century's average, but what about the variation about that average? What was the maximum number in a year? What percentage of years had a number greater than the current number? We need more than a single number to tell whether exceeding the average is meaningful.

[Jack Hydrazine]

Have no idea if it is within natural variation.