The Geysers Geothermal Power Plant

Eruptions reader (and former hallmate at Oregon State) Ed Kohut sent me a message today pointing out that there is an ongoing earthquake swarm in the area of the Geysers in northern California. Now, I don’t know what the normal seismicity is underneath the Clear Lake area and this area is part of the San Andreas fault system, so these earthquake are likely not volcanically related, but I post them here just as a reminder of how difficult it can be to deconvolve these geologic signals.

The Geysers are part of the Clear Lake volcanic region, which is still considered active, last having erupted in ~10,000 years ago, producing maars and tuff cones. The Geysers geothermal field is believed to be heated by a remnant silicic magma chamber under the Clear Lake area. The Geysers area is the largest producing geothermal field in the world!


  1. #1 Elaine Supkis
    May 6, 2009

    The steam at this site is created by flushing in fresh water all the time and this causes the site to ‘breathe’ in and out. The cluster quakes have been going on since it was launched. Back in the early 1970’s, I and others campaigned against installing this energy plant. I explained, this wasn’t like Iceland with them tapping into a volcano, this is along one of the most dangerous slip/slide fault systems on earth! But we were overruled.

    The number of quakes have increased in volume and intensity in the last 2 years. I write about it at my blog periodically. Below is one such story from January, 2007:

  2. #2 Erik Klemetti
    May 6, 2009

    Thanks for the comment, Elaine. I’m glad someone with a little more familiarity with the seismicity of the area could chime in.

  3. #3 Elaine Supkis
    May 6, 2009

    Quite alright! My blog has lots and lots of stuff about earthquakes. It is rather peculiar but my dad is Dr. Aden Meinel, founder of many observatories and one thing he had to look for was geological stability. This is why he built no observatories in California, etc. The earth’s tectonic movements are utterly fascinating and we really don’t know all that much but scientists are closing in on many aspects of it thanks to satellites, deep drilling, etc. A very exciting field!

  4. #4 Mike
    May 6, 2009

    You might also be interested to know the micro-quakes directly map to drilling in the area. As drilling increases (rework or tapping into the field) the quakes increase. For the past two years two new plants have been under development and if you watch the USGS map of the area, you can see when they’re drilling and when they’re not. Base level non-drilling is about 100 micro-quakes a week. While drilling, it doubles.

    Also, as Elaine notes, about 30% of the volume extracted is being reinjected into the reservoir, that also contributes. Finally, since 70% of the mass isn’t replaced, a fair amount of the activity can be attributed to subsidence.

  5. #5 Curtis
    May 13, 2009

    This morning (200905.13 14:25 UTC – 07:25 AM PDT), as I looked at the CA/NV USGS quake report:

    I noticed a continuation of, what I consider, a “swarm” appearing around The Geysers, Anderson Springs, Cobb Mountain, and of interest was activity near Hidden Valley.

    I live on Cobb Mountain, CA, currently run ARPSN (Amateur Radio Public Seismic Network), and am doing FFT-CSP Seismic Animation (related to teleseismic events, hum, and tilt) for a project I am working on with Dr. Randall Peters (physics) from Macon, GA. There is another PSN participant in Redwood City.

    Here is the location of my seismic heliplots, N6ECT-1/ARPSN-1 Seismic Alert System, Cobb (Cobb Mountain), California, 95426, USA

    I placed the location of the main seismic page in the supplied URL box included with this entry; however, if it does not pass, all the animation and references to seismology in the local area mentioned are located at:

    I hope this helps, because the above information is region specific and (fwiw) I also enjoy Volcanology from an amateur perspective and have greatly appreciated related “Hum” studies.

    Thank You A Great blog.

  6. #6 Joseph Wildhagen
    May 21, 2009

    I took the boys camping by the Long Valley caldera (Mammoth Lakes, CA) twelve years ago. Of over a dozen roughly developed hot spring pools, most were already too hot to use. Hot Creek (runs into Owens River, H2O source for Los Angeles) had already killed a dozen swimmers (intoxicated party animals) venturing away from the designated “safe” swimming area, and is now closed due to geysers blowing up in the middle of the river. We swam there twelve years ago and you could feel the steam shock waves from river bottom, perhaps thirty feet below, below your feet. The caldera is nineteen miles in diameter, last eruption launching seven cubic miles of rock. Mammoth Lakes Chamber of Commerce got an injunction against media fear mongering for earthquake swarms about thirty years ago, and we need to be careful to be facinated by life on the edge of the Pacific Rim of Fire, be careful when close to “events,” but not get unduely excited. We have many active volcanos, and they “talk to us” before eruptions. More active times are fun to observe, but demand respect, not undue fear. Most of California is already prepared for “big ones,” building codes protect us, and we need to take responsibility to anchor hot water heaters, and other stuff that might move or brake. We should read and heed and be prepared for “fun.”

  7. #7 robin purcell
    June 30, 2009

    Does anyone know how the 4.0 today in this area is located vis a vis the deep drilling for geothermal energy? thx robin

    July 13, 2009


  9. #9 Chad Attermann
    September 4, 2009

    It’s interesting to note that recent seismic research suggests that injection of fluids into active faults, especially slip faults like San Andreas, can actually have a “lubricating” affect that allows stress to be relieved in small “micro” quake bursts instead of building into catastrophic events. The small swarms in the Geysers area may very well be a manifestation of this phenomena.
    Regarding the comment about reinjection and subsidence, that may have been the case in the past, but currently milllions of gallons o treated “grey” water is piped to the gethermal fields and injected along with the spent geothermal fluids to recharge and sustain the system.

  10. #10 jeffree
    October 11, 2009

    I also live on Cobb Mountain. I have recently noted the presence of numerous petroglyphs, in my very own backyard, which is the South facing slope of the Volcano Cobb Mountain. These petroglyphs seem to depict a warning regarding the intense energy that was bombarding the hominids of that time, possibly about 1 million years ago, early paleolithic period. There are clear carvings of arrows pointing to the Sun. There are also some stick figures which may be humanoids. I’ve uploaded photos of these petroglyphs to my picasa website for your perusal. I would appreciate any feedback anyone can give regarding these discoveries.
    Peace, love, and light

  11. #11 jeffree
    October 11, 2009

    The link to my website, which didn’t make it into the last post, is:
    Thank you.

  12. #12 rhair
    January 17, 2010

    This message is in response to Joseph Wildhagen post.

    There has not been dozens of deaths of any swimmers in the Hot Creek or Mammoth Lakes Hot Spring area hot springs due to unusual activity or intoxicated wanderings into off limit areas. Please post responsibly and no not make up untrue stories.

  13. #13 Joseph Wildhagen
    February 25, 2010

    Unfortunately, yes there have been fatalities. Read

  14. #14 Rodney
    March 2, 2010

    I have been watching the USGS site, Cal/Nev for about 10 years now. ( lets say late 90S… forward). Way back then,”IF”, my memory serves me well, there were about 450 to 550 quakes per week… in Cal Nev combined. Now… 650 to 750/week with a crazy peak of 900 in the second half of 2009. Today we are back down to the low end of 700.
    If you search around for Mammoth related info (on-line), there are warnings about camping in certain areas due to dangerous levels of gasses. I recall that they had posted signs at some trail heads, warning of dangers to pets, who get their air closer to the ground, and takeing naps in the wrong places with say,”a baby”.
    I recall seeing pictures of dead bodies floating in a hot pool,(too hot…), but that was a strip of film from the movie Volcano or Dante`s Peak…FICTION,in other words.
    Here`s a warning for you, USGS, in conjunction with the State of Nevada insurance regulators put out a warning that property owners should bone up on insurance and personal safety issues as relates to earthquakes in the Cal Nev area.
    The article stated that Geologists ( there are millions of them,…), but some of them, give a an estimation of a 100% certainty of a 6.0 or greater Quake in the next 30 years. When I extrapolate, I see a high potential for worse….
    So the good professor is right, “use common sense”.
    I would just like to add, don`t warm your hands over an active gyser.

  15. #15 smow
    March 4, 2010

    wah wah wah… quit whining about quakes on cobb.

  16. #16 Pamela Britton
    March 4, 2010

    Looks like they’re shake, rattle and rolling again today. Whew!


  17. #17 Mario
    April 10, 2010

    This is amazing in that now the quakes are completely south, san andreas wise, in the mexicali area. Soon they will move upward north, probably passed Geysers then to Southern CA.

  18. #18 Dustin Hartmann
    July 15, 2010

    well im here to say i live the lake county area its very beutiful especially on cobb mt i also work in the geysers provideing energy for the north bay area. NOW theres lots of speculation about how the geysers are bad for the inviroment well ive got news for u speculators the geysers are here to stay with out the power plants and the man power to control the steam flow there u out of towners that are trying to make it hard for me to support my family of nine would really be trouble we control that source of power so that it is not a air born threat. If u go back a hundred years ago it was almost like yellow stone unpredictable and yet possibly deadly so if we wernt there well u know if u really have a clue how deadly some of that hott water or deadly gases can be so let us do our jobs or leave the wonderful ring of fire area u have recently moved to.

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