Swarm of quakes near Mammoth

mammothairportnightU.S. Geological Survey scientists continue to monitor the Mammoth Lakes area where a swarm of some 500 smaller magnitude quakes have rocked the area around Mammoth Airport. Scientists say the swarm poses no immediate danger. No damage has been reported.  Residents say they have felt the temblors.  Here is what USGS reported:

Earthquake Swarm in Long Valley Caldera not Volcanic in Origin
September 26, 2014
We have been closely tracking an earthquake swarm in California’s Long Valley Caldera, which started yesterday at around 4AM PDT (September 25, 2014). The swarm is located 7 miles east of the town of Mammoth Lakes, about a mile north of the airport. From about 4 AM on the September 25th to 11AM on September 26th there have been more than 500 earthquakes of magnitude M1.0 and above, including 8 earthquakes between M3.0 and M3.8, which were felt locally. This is one of several earthquake swarms that have occurred in the caldera this year. Despite the several felt earthquakes, this is still rather modest activity compared with the much more energetic swarms occurring in the 1980s and 1990s. We do not see any evidence for anomalous ground deformation associated with the swarm at this time. Part of the Long Valley Caldera, known as the “resurgent dome,” has been uplifting at a rate of about an inch per year since late 2011, and this remains unchanged. Caldera uplift has occurred sporadically for the last few decades. The uplift rate observed since 2011 is small compared to rates observed in the 1980s and 1990s. The earthquakes themselves are small, brittle-failure (rock breaking) events. Such events are sometimes called “tectonic.” The earthquakes do not result from the underground movement of magma. We can distinguish between brittle-failure earthquakes and those resulting from magma movement by the characteristics of the seismic waveforms.
The swarm events pose no immediate hazard. The USGS California Volcano Observatory will continue to closely track this activity and provide updates as appropriate.

13 Responses to Swarm of quakes near Mammoth

  1. Desert Tortoise September 27, 2014 at 2:42 pm #

    Thar she blows!

  2. Wayne Deja September 27, 2014 at 11:17 am #

    Debbie Rupp….Isn’t that the truth…..The way the L.A. broadcast came across…..IMO…..was nothing but drama and trying to infer something that’s going on that isn’t going on..and the same ole’ thing….L.A. newsmen and women stating “warnings and advise” on how to survive if something were to happen,kinda like we would all be small-town dummies sitting on a lawn-chair in our front yards waiting on the “authorities” to bring us a hamburger and a bottle of water… and “orders” on what to do next…when,in all actuality,the only thing any of us could do,if that caldera blew it’s stack,was to sit back,watch,take photos, and try to enjoy….then kiss it all good-bye.

    • Mark September 27, 2014 at 12:48 pm #

      Sit back, watch, take photo’s, and try to enjoy. That’s a fact Wayne, I’d sure hate to be taking a nap and miss the whole thing.

      Sam applies to the end of the World

  3. Sierra Lady September 27, 2014 at 9:47 am #


    “This ”swarm” of several hundred quakes (see below) were all located in the Long Valley area and centered about one mile north of the Mammoth Yosemite Airport and six miles east of Mammoth. They were measured at a depth of five kilometers, officals with the USGS said.

    David Shelly, a seismologist and geophysicist with the USGS said the quakes appear to come from the release of some carbon dioxide gas and water deep in the earth into existing cracks or faults in the ground under the Eastern Sierra.

    “This fluid moves episodically into cracks or faults in the crust,” he said. “We think these quakes were triggered by this movement but driven by existing tectonics.”

    B. Richter

  4. Debbie Rupp September 27, 2014 at 8:03 am #

    During the swarm in the 90’s they would show pictures of the lava in Hawaii while talking about the earthquakes in Mammoth. Giving the impression that lava was flowing down the streets of Mammoth. They also offered to pay me to cause damage to our business and let them film it. That is why I have no use for the big out of town reporters. This was a news affiliate out of Southern Calif.

  5. Greenflash September 27, 2014 at 7:58 am #

    Truth to USGS statement but not entirely. Calling it tectonic is really just semantics to abate hysterics, which is fine considering things went quite the day after. But looking closer, the depth of the magma chamber is @ 6-8 km below surface. Depth of the earthquakes was roughly 4.4-7km. So yes, rock was technically breaking, which is tectonic. But it was due to volcanic activity (dike injection, increased pressures in chamber, hydrothermal flow, etc…).

  6. Ken Warner September 26, 2014 at 6:24 pm #

    It’s all hogwash. The biggest temblor was only a 3.5. They were all centered somewhere in the middle of the Long Valley Caldera.


  7. Wayne Deja September 26, 2014 at 4:23 pm #

    …Sadly,it’s ALREADY started….on the 5;00 news,the anchorman was telling of this going on up in Mammoth Lakes with the earthquakes,and stating the “authorities” are holding back on anytype of connection to the Long Valley Caldera,and waiting on that info before “they” issue and/or “order” any mandatory evacuations of the area.

    • sugarmagnolia September 27, 2014 at 8:51 am #

      wow, such ridiculous hyperbole. Or, more appropriately, such unprofessional news reporting. Unfortunately, that seems to be the norm these days (Sierra Wave excepted of course).

      These two days were nothing compared to what went on for at least 5 years in the same area. That swarm culminated in a period of time with literally thousands of quakes per day for months, slowly increasing in power. It was maybe 97 or 98 when there were four quakes of 5.0 size in one day. After that, the earthquakes quieted down….I guess to the point where this tiny swarm gets media attention!

      I wasn’t here in 1980 when there was another, even larger swarm.

  8. Alice Chan September 26, 2014 at 3:23 pm #

    It’s not movement of the magma body? Is is possible that Casa Diablo Geothermal is doing something now to cause this swarm?

  9. Tinner September 26, 2014 at 2:24 pm #

    Wake me up when the earthquakes reduce property value.

    • upthecreek September 27, 2014 at 10:44 pm #

      Who has the sign that was at the shell station in the 80’s.
      “Last one out turn out the lights”

      I blame this swarm on the snow summit merger….

    • upthecreek September 27, 2014 at 10:49 pm #

      What property values do you speak of?


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