Saturday, March 22, 2014

Observing local earthquakes

With a day off in Dili, I had a chance to look over the data recorded overnight in Maliana and Oecussi.  It is always valuable to look at data while in the field, as it gives a chance to make any adjustments.  Also, with the upcoming presentation I will give to IPG, I will be able to show examples of the record that we will be creating.  I looked up local earthquakes from the USGS real-time webpage and found a few good candidates.
A catalog of earthquakes that occurred between 19-21 March in the region.  The event depicted by the light blue dot was recorded in Maliana, Timor Leste.

Because the two records I looked at were from the nights of 19 and 20 March, I had about 12 hours of data to look at from each station.  Maliana recorded data on the night of 19 March, and we were lucky to have a magnitude 5.2 earthquake occur off to the east in the eastern Banda Sea.  The record from our station clearly recorded this event:

The record for the entire event.  The P wave arrived in Maliana around 7 minutes after the earthquake occurred.

A zoom into the P wave arrival.  The middle trace is the vertical component - it shows the P arrival well.

A zoom into the S wave arrival.  The top and bottom traces are the E-W and N-S components, respectively. 

An encouraging sign indeed, especially in light of my concern that this station lies on the perimeter of a large sedimentary basin.  The record from the Oecussi station also revealed a few verified events, but displayed a lot of noise from motorcycles passing by on a nearby road.  I won't be surprised if we relocate the station in the future, but the record will make it clear if this is necessary.  For now, it is time to finish up the installation - on to Same and Atauro!

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