Hi Sue. What your seeing right now is a typical pattern for Yellowstone. This has been going since its birth millions of years ago.

Scientists have traced Yellowstone's origin to a hot spot in the mantle, one of a few dozen such hot spots on Earth. Buoyant material from a hot spot rises through the upper mantle, bringing heat from the Earth's interior closer to the surface. The Yellowstone hot spot impinges on the base of the North American plate, one of several rigid plates that make up the Earth's crust. These plates move a few inches per year with respect to the stationary hot spots and each other, sometimes causing great earthquakes as the plates collide, grind past one another, or split apart.

Although the latest eruptions were approximately 70,000 years ago, the immense hydrothermal system and a variety of geophysical characteristics indicate that magma still underlies the Yellowstone caldera at a shallow depth. A large negative gravity anomaly, low magnetic intensity, high electrical conductivity, shallow swarm seismicity, and large delays and high attenuation of seismic waves are all consistent with this inference.

Yellowstone lies at the intersection of the Basin and Range tectonic province, dominated by E-W extension, and the eastern Snake River Plain, a linear downwarp or graben that has been a locus for basaltic volcanism since middle Miocene time. According to one popular model, the rhyolitic Yellowstone Plateau marks the current location of a "hotspot" or melting anomaly in the upper mantle, and the basaltic Snake River Plain records the hotspot's northeastward track across the mobile North American Plate. Take Care…Don in creepy town.