Olancha Earthquake Sequence Update

Olancha Earthquake Sequence Continues - 435 Events Through October 7th, Activity Beginning Oct. 3rd Reveals New Structure Orthogonal to Previous Olancha Sequence Structures

Report by the California Integrated Seismic Network (Caltech/USGS)
Anthony Guarino, Egill Hauksson, Ken Hudnut, Sue Hough, and Bob Dollar

Update 10/7/09 09:21AM PDT

The Olancha Sequence continues with several more events since Friday evening, ranging in magnitude from M1.0-M4.5.The events beginning October 3rd distinctly show a new trend on a cross fault between the two existing structures. The two existing structures trend NW-SE, whereas the new Oct. 3rd events trend southwest to northeast. This new structure is likely a conjugate fault with respect to the existing structures, as the geology in the area is rather complex.

The migration of activity toward the new structure offers insight to the complex geology of the area, although the trend of mapped faults (shown in light blue) do not share the same strike as either of the previous structures from this week, nor are they orthogonal to the newest structure. The recent M4.0 earthquake which occurred on October 6th was located on the most northeast edge of the sequence. This extends the region of seismicity slightly to the northeast, while the event is still part of the more recent SW-NE trend..

Northwestward motion of the Pacific Plate, relative to a fixed North American Plate, takes place mainly on the San Andreas fault system and other faults to the west of the Sierra Nevada. A portion of the deformation, however, passes inboard of the Sierra Nevada block and goes up the eastern side of the Sierra Nevada. The Sierra Nevada have been moving slowly northwestward as a result, pulling away from the Colorado Plateau. The Basin and Range Province has resulted from this crustal stretching, and some right-lateral shear along the eastern base of the Sierra Nevada occurs as well.

The Olancha activity, occurring on both NW-SE and SW-NE oriented faults, is taking place in a complex area where the Sierra Nevada range front also bends. This bend, combined with the right-lateral shear along the range front, has produced an extensional step in the fault system and the hole created has been filled with a sedimentary basin that is now filled by Owens Lake, which is now, for the most part, a playa or dry lake bed. Interestingly, this bend in the mountain range front also coincides with the highest peak, Mount Whitney, and the recent Olancha activity is near the southern end of the 1872 Owens Valley earthquake, which ruptured a system of faults that run through Lone Pine [ earthquake.usgs.gov... ].

Originally posted by TrueAmerican
reply to post by Trexter Ziam

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Umm, did you actually read that thread, or just look at the stars and flags? No disrespect to my new found friend Hx3_1963, but unfortunately that thread was based upon the faulty BHE and BHN channels of CI.CWC station, and resulting speculation of symmetrical patterns on those channels.

And seeing as maybe you obviously didn't read that thread, then it would probably be a good idea if you did.

I felt it might be prudent to get some official information from the California Integrated Seismic Network (Caltech/USGS) regarding this swarm. The fact that there appears to be a new fault discovered here according to them was news deserving of its own thread I felt, if that's what you mean.

Originally posted by ANNED
The cracks in the pavement mean little, The secondary roads in Inyo county are mostly desert mix and the heat (pavement temps over 150º) crack desert mix within a couple years like that. And its been over 15 years since they repaved 190 in that area.

Aww geez, can't even have a little fun around here. OF COURSE I know the cracks in the pavement weren't due to... oh just nvm.

I wonder if the hot water flow at Dirty Socks mineral spring has changed any.
36º 19' 46.09"N 117º56' 57.74"W
www.panoramio.com...
Many times spring flows will change with earthquakes in the area.

www.abovetopsecret.com...
There are major 180 Deg N/S E/W slip/strike motions going on right now!!!

www.abovetopsecret.com...
The quakes are 180 degrees out of phase n/s e/w with constant z movement...

To me indicates a slip/strike is likely...

www.abovetopsecret.com...
what you are seeing is a north-west to south-east movement, in essence - a slippage on the fault line with little up/down movement.

www.abovetopsecret.com...
The two existing structures trend NW-SE, whereas the new Oct. 3rd events trend southwest to northeast.

The Olancha activity, occurring on both NW-SE and SW-NE oriented faults, is taking place in a complex area where the Sierra Nevada range front also bends.