Here are the findings from the investigation….
A report prepared for Jordan Sands into the April 25th tremors that shook Mankato says that they were most likely due to an earthquake and not from a blast at the company’s quarry.
The conclusion of the independent report from Barr Engineering says “Our analyses strongly indicate that the seismic event…was an earthquake and not a blast at the Jefferson Quarry that occurred about 7 sec earlier.”
The report also says the relationship between the blast and the earthquake is unknown. “If the earthquake was located at depth a few kilometers south of the quarry, we believe it is unlikely that there is a cause-and-effect relationship. In our judgement, the size of the blast would be too small to trigger an earthquake even on a critically-stressed fault.”