SEATTLE, Wash. — Scientists say the Puget Sound has entered a period of increased earthquake activity which may lead to a greater chance of earthquakes.

The Pacific Northwest Seismic Network posted a tweet Tuesday saying the Puget Sound Episodic Tremor and Slip, or ETS, has started, and posted a link to an interactive map showing hundreds of small tremors.

PNSN Professor Emeritus Steve Malone said that he believes the ETS started on August 11th south of San Juan Island.

Over this week the tremor has gotten stronger and more frequent but is not yet as near continuous as during some previous ETS events.

According to Central Washington University, an ETS can lead to large megathrust earthquakes.

ETS usually occurs every 14 months or so and last a few weeks.