Magnitude 6.3 earthquake in the Bering Sea last evening. A second, Magnitude 6.0 tremor occurred about 5 minutes later in the same location. The travel time curves are placed based on the first, larger one. The unmarked arrival to the right of the SS curve is the SS arrival for the Magnitude 6.0 event as shown below. In this image the travel time curves are placed based on the second Magnitude 6.0 event. Overlapping returns are usually more difficult to extract from a single trace than these signals.
As an aside, I have Amaseis running on an old HP/Compaq notebook computer with Windows XP Pro. Even though Windows provides a mechanism for updating the system clock using some variant of internet time, it doesn’t allow the user to set the frequency of the update. The clock was running about 2 minutes fast when these earthquakes took place so I have to compensate for the actual time difference in the analysis. I need to find a better way to update the system clock. Postscript: I had used a program called NMEATime in conjunction with a GPS receiver to set the time on my previous logging computer. I couldn’t use it with the GPS on the notebook because it only has one serial port. However, the program can also synchronize to network time servers at a user programmable interval so I installed it to synchronize the system clock.