SEATTLE (AP) — Officials are tracking the largest swarm of earthquakes in more than 15 years on Washington's Mount Rainier but say there is no indication that the cluster of quakes is cause for concern. The U.S. Geological Survey Cascades Volcano Observatory said the swarm began early Tuesday at the 14,410-foot (4,392-meter) volcano near Seattle. The swarm has consisted of hundreds of small earthquakes — the largest of which so far has been a magnitude 2.3 — and has surpassed a 2009 swarm in terms of magnitude, event rate, total events and energy release, the agency said in a statement Thursday.