Poe Field Dormitory Construction Blasts Recorded on the Guyot Hall Seismometer

Tuesday, Feb 25, 2020

Recorded blast graph

 

Taking a break from recording worldwide earthquakes and other natural and cultural noise, on February 18, 2020 (Julian day 49) and February 21, 2020 (day 52), the Guyot Hall seismometer, a Nanometrics Meridian Compact PH 120 s broadband instrument, recorded two of the sequence of planned construction blasting events originating south of Poe Field on campus.

Vertical ground displacement is shown in nanometers (nm), filtered between 0.2 Hz and 10 Hz. Timing is in seconds (s) after 16:00 GMT, consistent with the events happening at around 11:30 and 11:43 local time, respectively.

The second event was noticeably "louder" than the first. Its wave train had a duration of about 3 s, with peak displacements reaching 2,000 nm, i.e. 2 micrometer, or 2/1000ths of a millimeter (some 25-30 times smaller than the typical diameter of a human hair!) The accelerations experienced by our instrument amounted to about 3/1000th of the acceleration due to gravity. Minor shaking was felt throughout Guyot Hall, the blast was audible, and the air pressure wave made the windows briefly shake.

In the event of a real earthquake, remember to "drop, cover, and hold on"!

For more information about the construction blasts:
https://facilities.princeton.edu/outages/loud-noise-possible-vibrations-1140a