Bible Answer

Should I be concerned about the increase of earthquakes?

In the Revelation study, Pastor Armstrong talks about the increase of earthquakes being a sign we are in the end times. But are there more earthquakes registered only because we have better technology?

You are correct about technology becoming more advanced, but this is only in regards to being more sensitive for detecting small earthquakes. In the Revelation study, Pastor Armstrong is referring to the trend in measuring large earthquakes (magnitude 6 and above) which have been reliably measured for nearly 100 years. However, it's important not to look at a single sign of evidence (absent of all other signs), but viewing the increasing number of all of these signs (famines, wars, earthquares) as collective evidence for the coming End Times.

In Christ's Olivet Discourse we read:

MATTHEW 24:7 For nation will rise against nation, and kingdom against kingdom, and in various places there will be famines and earthquakes. 
MATTHEW 24:8 But all these things are merely the beginning of birth pangs.

So, we should continue to be ready to welcome our Lord's return and live with eyes for eternity.