Below are two images captured from the TUC Seismographs in Tucson Arizona. These are offered so that all those who have been asking about reading seismograms, so they can view two known Large Events, study the Arrival Time delays due to Distance, and the Amplitudes due to Distance and Magnitude. This is strictly for study purposes. Our thanks go out to the TUC site for offering these images, and a Great Internet Resource.

1) On 8/20/97, at 7:15 GMT a 6.0Ms Quake occurred at Latitude4.64N, Longitude 96.33E in Northern Sumatera, Indonesia.

2) On 8/20/97, at 13:51 GMT a 6.4Ms Quake occurred at Latitude41.54S, Longitude 80.19E on the Mid-Indian Ridge in the Southern IndianOcean.

The first image is from the Long Period Instrument, note the 6.0M onthe top, and the 6.4M below.

This second image is from the Non-Filtered instrument, again you cansee the 6.0M arriving a little after 8:00, and the 6.4M arriving sometimeafter 14:00.

Please, if you get a chance, stop by TUC and offer thanks for their fine material and information.