According to the Loudoun County Sheriff’s Office and online sources, a small earthquake hit northeast of Belmont, Virginia late last night. Belmont is a census-designated area along Belmont Ridge Road in north Ashburn.
The 1.7 magnitude quake was felt by many — primarily in the Lansdowne area — when it struck at 11:23 p.m. The Loudoun County Sheriff’s Office quickly put out a statement. (The release says “after midnight” but online sources indicate it was earlier.)
On social media, area residents in Ashburn and Lansdowne reported hearing and feeling the quake.
“Anyone hear a faint boom and have their house rattle…?” one poster asked. Some speculated it was a transformer blowing or construction work being done. But it was quickly confirmed as an earthquake.
(Image at top: Google Maps)
That’s it I am moving to San Francisco where it is safer!
The epicenter was quite near the quarries, about where the W&OD trail crosses Belmont Ridge Road. By no means certain, one factor that may have contributed to this, was the massive volume of rock quarried in the area over the decades, which can cause minor isostatic adjustments (uplift or lateral movement) in the bedrock. This can cause minor earthquakes, on the order of what happened last night. In Belmont, we feel quarry blasting regularly as a minor thump–not a big deal. Minor earthquakes like this are nothing to be alarmed about, and most people would not even have noticed a 1.7 magnitude event.
The 5.9 magnitude event near Culpeper in the summer of 2011 was a totally different situation, where it was impossible not to feel the significant effects in Belmont. Remember, the scale is logarithmic, so a 2M event is 10x larger than a 1M event, a 3M is 100x larger than a 1M, a 4M is 1000x larger than a 1M, etc.
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