Hi Petra. Gee! What a grouch. I always enjoy the way you look when you’re irritated with me. The way your hair stands on end and your eyes rotate. One clockwise and the other counterclockwise. I promise you will be the first to know if an when I discover the answer to my question (s).

I think I may have an answer to your question about geysers and earthquakes.

Three components must be present for geysers to exist: an abundant supply of water, an intense source of heat, and specialized plumbing. Remote locations or locations legislatively protected from human activity are becoming increasingly important to maintaining geysers. The set of requirements make geysers a rare geological phenomenon. Water is sometimes not available, as in an arid part of the country. Heat may be close to the surface only along a fault line, where a tectonic plate is being subducted, from volcanic activity, or from a hard to explain hot spot. Even if both water and heat are present, the right plumbing is critical.

For water to be spit tens of feet into the air, geyser plumbing must be both water- and pressure-tight. Rhyolite, a volcanic rock high in silica, generally provides the seal. Rhyolite deposits a water-tight seal along the walls of the geyser plumbing. Most of the geyser fields in the world are found in rhyolite, but rhyolite fields are relatively uncommon. The right mixture of water, volcanic heat, and plumbing occurs best at Yellowstone National Park.

Geysers are known for their often spectacular eruptions that throw water and steam high into the air. From an economic and public safety standpoint, some geysers have shown certain precursor activity prior to earthquakes. During the period 1973 to 1991 the interval between eruptions from a periodic geyser in Northern California exhibited precursory variations 1 to 3 days before the three largest earthquakes within a 250-kilometer radius of the geyser. These include the magnitude 7.1 Loma Prieta earthquake of October 18, 1989 for which a similar pre-seismic signal was recorded by a strain meter located halfway between the geyser and the earthquake.

The underground structure of a geyser consists of a crooked tube-like opening that leads from the interior to the ground surface. Several small caverns or chambers may be connected to the tube. Groundwater partially fills the tube and some of the connecting caverns. The heated water is trapped under pressure in the crooked tube [258]. Continued heating produces a water temperature above the boiling point, and the steam so produced develops enough pressure to eject a small amount of water to the surface. This expulsion of water in the initial upsurge reduces pressure on the superheated water in the tube. The reduction in pressure causes the remaining water to boil explosively to the point where it drives a column of water and steam, called the geyser jet, into the air. The eruption continues until water and steam are driven out of the tube and storage caverns.

The hot water, circulating up from great depth, flows into the plumbing system of a geyser. Because this water is many degrees above the boiling point, some of it turns to steam. Meanwhile, additional, cooler water is flowing into the geyser from the porous rocks nearer the surface. The two waters mix as the plumbing system fills.

The filling and heating process continues until the geyser is full or nearly full of water. A very small geyser may take but a few seconds to fill whereas some of the larger geysers take several days. Once the plumbing system is full, the geyser is about ready for an eruption. Because the water of the entire plumbing system has been heated to boiling, the rising steam bubbles no longer collapse near the surface. Instead, as more very hot water enters the geyser at great depth, even more and larger steam bubbles form and rise toward the surface. Somewhere they encounter some sort of constriction or bend in the plumbing. To get by they must squirt through the narrow spot. This forces some water ahead of them and up and out of the geyser.

We know that before the Loma Prieta quake the Geysers at Calistoga changed their eruption pattern. The only thing that comes to mind that would change the time for the eruption is the way for the water to erupt. As the rock started to fracture it increased in size. This is where we get the tilt from just before a quake. The area of swelling depends upon how large the rock is to start with. The larger the rock the greater the area it will affect when it starts to fracture. When that swelling reaches the Geysers it either causes a situation where less water is able flow into the area to be heat, or it affects the tube, or channel by which the water erupts from. My feeling is that it temporarily narrows the tube by which the water can erupt. It then returns to normal after the quake.

That’s my theory. I have no idea if it’s the right one or not, but as soon as I know I promise you will be the first to know. Take Care…Don in creepy town