Bayou Corne Sink Hole

The main purpose of this page is to annotate any unusual events if possible and to keep a record of the seismograms in a standardised scale so comparisons are relevant. I will also use it to give some explanations of reading seismos.

Links to seismogram page. Below each seismo on the seismogram is a link to get today’s seismogram in the wide format (new page), or yesterday’s seismogram or the day before that. Then there are links to archives of each month available.

LA10 (3)	LA11	LA12	LA13	LA14	LA15
LA16	LA17

Cultural Noise

How do we determine cultural noise on a seismo? Basically this is patterns which predominantly occur at more or less the same time each day and tail off around the same time each day. Thumbnails, such as are on the pages, are particularly useful for identifying this. Below is an example from LA02.

The third thumbnail down on the right is quieter than most, so why is that? Basically because that is the 22nd November which is of course Thanksgiving in the US. These thumbnails are in reverse order so the next one left from that is Black Friday with a little bit of traffic, then the next across is the Saturday. The one immediately above the 22nd is the Sunday. After a peaceful Thanksgiving weekend it is back to normal on the Monday, next left from the Sunday.

To help you identify the days above here is thanksgiving marked, and the is 3rd down on the right on the full image.

If this is traffic, or much of it is traffic, then we should be able to see vehicles moving past LA01 and LA02 in different directions. In deed we can. Take a look at day 314. This GIF will make you go cross eyed, but look between 0700 and 0800. You can see a red signal moving to the left and a blue signal to the right. Just after before 0900 over on the right you can see a green signal moving to the right – moving from LA02 to LA01.

YOU MUST RIGHT CLICK AND VIEW IN A NEW TAB OR WINDOW FOR THE GIF TO WORK.

Once you know what you are looking for you will be able to identify many more.

GS seismograph travel times.

The tables below give the travel times (approximately) from the sink hole location to each of the seismos. Bear in mind this is approximate because the Latitude and Longitude given for the seismograph stations is only to two decimal points and the measuring is being don manually on Google Earth.

The travel times are given for three speeds of seismic wave and for sound in air.

Identifying an airborne sound

On most of the seismograms it is very difficult to actually find two signals that match, which is another matter, but here I am looking at two which do appear to match. In the first diagram I have circled the two spikes

LA03 is ~0.26km from the sink-hole and LA06 is ~1.22 km.

In close up those two traces look like this.

There is a good probability that those two signals are the same. The mark on the upper one is not part of the signal, it just the cursor position. The difference between those two is ~4 seconds therefore if that was a seismic event the source would have to be at the minimum 12km further away from the source for the later signal, and more likely 32km, BUT if that signal is being produced by an airborne sound and here I am using the memory (not good!) sound travels ~750 ft per second (at msl).

This is approximately 0.2286 km per second and that would make the second seismo 4 x 0.2286 km further away which is 0.914 kilometres. The difference in distance from the sink hole is 0.95 km given that these are not very accurately located. That seems to me to make this signal airborne rather than a seism if those are both the same event. (And yes loud sounds do show on a seismogram – e.g. sonic booms etc)

Update: It looks as if the seismograph stations LA01, LA02, LA03, LA06, LA08 and LA09 have been taken off line.