M3.5 – 4km ESE of Nelsonville, Ohio

20Nov2013_Ohio

I received an email notification this afternoon that a Magnitude 3.5 earthquake occurred east southeast of Nelsonville, Ohio just before 1:00 pm local time.  My heligraph has been very noisy so I couldn’t really see any signal even though the epicenter was only 79 miles south of Millersburg where I am located.  When I zoomed in on the trace though I could see an excursion at about the right time.  Just to be sure I checked a nearby helicorder located at Kent State University Branch campus in New Philadelphia, one of the OhioSeis network stations.  It showed the first arrival at about 20 seconds past 18:00 UTC, the same as mine. There were 373 felt reports by mid afternoon mostly in southeastern Ohio..

 

Postscript (April 27, 2014) :

In an email exchange with another amateur seismologist, he had included a link to additional information on using the AmaSeis software.  As I read some of the entries I found an article on analyzing local events so I applied it to this event in Nelsonville, only 79 miles south of my seismograph.  One of the characteristics of local earthquakes is that they have a higher frequency content than more distant teleseismic events. These can be extracted by using a high pass filter on the signal.  Following the lead of the article, I applied a 1.2 second high-pass filter twice to the Nelsonville signal with the results shown below.  Impressive!

nelsonviller_Nov2013revisit1

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s