triggered earthquakes

On Monday, airline passengers were the first to observe the eruption of the just-barely-above-the-water volcano that forms the islands of Hunga Tonga and Hunga Ha'apai, in Tonga. Three days later, a magnitude 7.9 earthquake occurred on the Tonga trench. Was the timing of these two events just coincidence? Yes. Why do I think the events were unrelated? Well: Earthquakes happen all the time. Thankfully for Tongan residents, I am using a geological definition of "time" here, but still: A major earthquake on a major plate boundary does not require any special explanation. The earthquake was a…