Hi Todd and Don,

I believe Todd's post referred to both foreshock and aftershock probabilities and I think the attached link will actually answer questions in regard to both sets of circumstances. However, one must realize that there is no definitive answer as to whether an earthquake is a foreshock until the larger main event arrives. If that were not the case we would all be on the move every time there was a 5.5 in California. LOL

And yes indeed a 5.0 quake can be a memorable experience, though usually not a life threatening one. I once rode out an earthquake in a masonry building in San Francisco. I recall the pole lights swaying to and fro, the windows rattling, the floor moving like an ocean. Meanwhile people were stuck in the elevator and screaming in terror. I rather felt like a trapped rat. I believe it was after that quake I wasn't so fearful anymore. The building was red tagged after the Loma Prieta earthquake, leveled and a new structure built in the same location.

As a side note, the woman Todd referenced in his post is Kate Hutton.

Petra

• Aftershock Probability Study