Earthquake Report: Tajikistan!

We just had an earthquake in Tajikistan with a magnitude of M = 7.2. Here is the USGS website for this earthquake.

We had a M = 7.5 in Afghanistan in October of 2015, less than 2 months ago. That earthquake was a reverse/thrust earthquake, today’s earthquake was a strike-slip earthquake. I will try to post more on today’s earthquake later.

Here is my interpretation map. I plot today’s earthquake, with the moment tensor, and the Modified Mercalli Intensity Contours (MMI). I am not certain, but based upon the tectonic map that I have found, which shows the northward motion of the Pamirs into this region, suggests that there is something akin to escape tectonics going on. Basically, there is crust squishing to the east and west due to the north-south convergence of the Pamirs. There is a left lateral strike-slip system to the west and a right lateral strike-slip fault system to the east. This fault system is labeled the MPT. Given this, I interpret this earthquake (with just 5 minutes to think about it) to be a left lateral earthquake along the MPT, or possibly the Kunlun suture. I will need to look at this more closely. The lower left inset map comes from here. The upper left inset comes from here.

UPDATE 2016.01.02

h/t to Eric Fielding, @EricFielding, Geophysicist at Jet Propulsion Laboratory, Caltech. There is an interoferogram for this earthquake which supports a northeast striking fault (Karaku fault). Here is the tweet that includes this interferogram from Raphael Grandin, @RaphaelGrandin, Associate Professor at Institut de Physique du Globe de Paris (IPGP). I updated the map to include this interferogram and the best interpretation for the sense of motion (left-lateral, northeast striking, strike-slip earthquake).

/UPDATE


After looking at this for another minute, it appears that today’s M 7.2 is south of the Kunlun suture (so not along the MPT), possibly along the Tanymas suture (above the label “Central Pamir”) in the lower left inset map. If so, this would be aligned with the right-lateral solution (not the left-lateral I interpreted just moments ago). Clearly, this needs a little more investigating. Here is a large scale map that shows the large lake to the northeast of today’s earthquake. This lake shows up in the lower left inset map. I include this inset map below.


UPDATE 2016.01.02

h/t to Raphael Grandin, @RaphaelGrandin, Associate Professor at Institut de Physique du Globe de Paris (IPGP). Here is a map from Schurr et al. (2014) which shows the Karaku fault, a northeast striking fault that this earthquake may have ruptured (or at least, a fault related to the KF).


/UPDATE

This map comes from here.


Based on the PAGER report, this could lead to casualties.


Here is another regional tectonics map from here. This also shows the convergence int he Pamirs.


    References:

  • Schurr, B., L. Ratschbacher, C. Sippl, R. Gloaguen, X. Yuan, and J. Mechie, 2014. Seismotectonics of the Pamir, Tectonics, 33, 1501–1518, doi:10.1002/2014TC003576.
Category(s): asia, College Redwoods, collision, geology, HSU, plate tectonics, strike-slip

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