The Backwards Earthquakes

Eos.org ^ | 12/15/2016 | Erin Ross

[Mr. K]

you're all wrong...

It's Global Warming!

[JimSEA]

Parts of larger plates move, spread and, in this case, change their orientation in relationship to other portions of their plates. They will collide and split apart according to stress and strain as defined in geology. Structural geology is the study of these movements.

There are 5 main concepts with which students struggle when thinking about stress and strain:
1. rocks deform,
2. stress causes strain and strain results in structures,
3. different physical conditions create different structures,
4. inferring stress from faults, and
5. the relationship between analogs and reality.

In this case the stress inferred from the strain and structure of the faulting indicate a “swirling” structure of rotation within the crust. Plates are not entirely independent of each other so a rotation within one plate impacts others. It may be expressed by different rates of subduction along a single plate edge. Thus, there might be a rotation of a plate or portion of a plate.

[Mrs. Don-o]

Ha!

[onedoug]

Any info on depths? Thanks.

[JimSEA]

Sorry, no.

[onedoug]

Thanks anyway. I might go back and dig through the data.

[JimSEA]

Let me know. From the article one would expect depths ranging from surface into the asthenosphere.

[onedoug]

0.2 to 18km for San Point over the past 3 months, trending NNW/ESE.

Four to seven months ago, a series trending N/S with a 2.7 at 20km.

These have been pretty mild with the greatest at 4.3, 9km. Though they seem to indicate a fairly complex variety.

Some very shallow, some quite deep for a significant distance from west coast subduction.

Your map indicates a rotational setting semi-surrounding this array from E to NNE.

Seems an interesting paper could come out of it.

[JimSEA]

Thanks, I quite agree.

[SunkenCiv]

Mere earthquakes. Thanks JimSEA.

join or quit view topics view or post blog bookmark post new topic subscribe