Complex sentence: The initial portion of work included nearly a full week of setting up the seismometers and optimizing their operation and, with that complete, two full weeks of continuous operation was then completed with twenty six seismometers distributed over 1500 square kilometers.
Split into simpler sentences: The initial portion of work included nearly a full week of setting up the seismometers and optimizing their operation. With that complete, two full weeks of continuous operation were completed with twenty six seismometers distributed over 1500 square kilometers.