Are you wondering why you didn't feel the Tuesday evening earthquake? The earthquake was felt by some people in towns north of Boston, but not by others, even in the same town.

Danvers Patch's Facebook page is a perfect example - while most people said they felt it, but others not far away said they did not feel it. 

Earthquake shaking tends to be amplified in areas where there are soft soil conditions, according John Ebel, the director of the Weston Observatory, which studies and monitors earthquakes. If you live near a landfill, you will likely feel shaking more strongly than if you live on rock formations, Ebel said.

Also, some buildings have a stronger tendency to shake more than others, Ebel said. For example, some residents near the Virginia earthquake in 2011 felt the tremors, while others did not, he said.

Human sensitivity to tremors is another factor that determines whether they will feel earthquake termors, Ebel said. Humans have a natural sensitivity to feeling vibrations, but some are more sensitive than others, Ebel said. 

Ebel said the earthquake's final magnitude was 4.0, and the quake originated near Hollis, Maine. Ebel called it a "mild to moderate" tremor for New England. Earthquakes greater than a 4.0 magnitude occur every five to eight years, he said. The last earthquake above 4.0 in New England was in Bar Harbor, Maine, in 2006, he said.

When was the last time you felt an earthquake?