Felt a mild tremor on a bridge

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In summary, the speaker experienced a brief shudder on a sturdy walking bridge over the Kennebec River, which they reported to the USGS but did not find any evidence of an earthquake. They question if a small woman passing by could have caused the shudder and suggest checking with local authorities for any structural issues with the bridge.
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About 1:20 this afternoon, I was standing on a very sturdy rigid steel walking bridge spanning the Kennebec River in Skowhegan. I was bracing my forearms against the railing and taking a picture of the river valley downstream, when suddenly the bridge shuddered for a few seconds. I looked up quickly only to see a fairly small woman approaching, and she smiled and said "hi" as she passed, seeming not to have noticed anything out of the ordinary. I made a report to the USGS, but have seen nothing on the Internet to indicate that we had a mild earthquake. I don't see how one small (100-110#) woman could cause such an effect, though, and it passed before she actually reached my position anyway.
 
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Nothing so far this evening.

http://earthquake.usgs.gov/eqcenter/recenteqsus/Maps/US10/42.52.-75.-65.php

The closest 2+ quake was Magnitude 2.7 - SOUTHERN QUEBEC, CANADA
http://earthquake.usgs.gov/eqcenter/recenteqsus/Quakes/ld1020012.php

Tuesday, April 10, 2007 at 10:05:10 (UTC) = Coordinated Universal Time
Tuesday, April 10, 2007 at 6:05:10 AM = local time at epicenter

Perhaps it was very localized and less than 2.0 Mag.
Maybe the bridge structure shifted. If there are piers in the water, could there be scouring of the bridge piers? Is it only a walking bridge?

Perhaps one should notify the local town or county or DOT office.
 
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Thank you for reporting your experience on the bridge this afternoon. It is possible that what you felt was a mild earthquake, as even small tremors can be felt on sturdy structures like bridges. However, without any confirmation from the USGS or other sources, it is difficult to determine the exact cause of the tremor. It is also possible that the woman passing by may have caused a slight vibration on the bridge, but it is unlikely that she would have caused a noticeable shudder. I would suggest keeping an eye on the USGS website for any updates on seismic activity in the area and also checking with local authorities to see if there were any construction or maintenance activities happening on the bridge at the time. Thank you for making a report to the USGS and for bringing this to our attention.
 

1. What causes a mild tremor on a bridge?

A mild tremor on a bridge can be caused by a variety of factors, such as strong winds, heavy traffic, or nearby construction. It can also be a result of natural phenomena like earthquakes or landslides.

2. How can a mild tremor affect a bridge?

A mild tremor can cause a bridge to vibrate or sway, which can potentially lead to structural damage. It can also affect the stability and safety of the bridge for vehicles and pedestrians.

3. Are all bridges designed to withstand tremors?

No, not all bridges are designed to withstand tremors. The level of resistance to tremors depends on the specific design and construction of the bridge. Some bridges may be built to withstand specific levels of tremors, while others may not be designed with tremors in mind.

4. How can scientists measure tremors on a bridge?

Scientists use a variety of tools and techniques to measure tremors on a bridge. These can include seismometers, accelerometers, and strain gauges, which can detect and record vibrations and movements on the bridge.

5. What implications do mild tremors have for bridge safety?

Mild tremors can have significant implications for bridge safety. They can cause damage to the structure and compromise its stability, potentially leading to collapses or accidents. It is important for engineers to consider the potential effects of tremors when designing and constructing bridges to ensure their safety and durability.

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