Where have aftershocks been occurring in the last week? This map shows seismicity since March 6 (red) with earlier aftershocks (gray). Mapped faults are in blue.

#TurkeySyriaearthquake

1/
The central part of the M7.8 (~Gaziantep) is pretty quiet now, and Hatay has only moderate seismicity.

Aftershocks are concentrated along the northern part of the ruptures, especially on the eastern (~Malatya) and western (~Göksun) ends.

2/
The time series shows that, as expected, the aftershocks are slowly decreasing, with the largest events ~M5. Larger aftershocks are still possible but less likely every day.

3/
Remember that each step on the magnitude scale is a factor of 30x more energy - so compared to a M4, a M5 is 30x more powerful, and a M6 is 900x more powerful. These smaller aftershocks are much, much smaller than the main shocks and are normal after a big earthquake.

4/end

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More from @JudithGeology

Mar 14
If you're not an Earth scientist, you probably don't understand what this paper is about, starting with the title.

That is normal - and it isn't bad! - scientific results have to be communicated with technical language within the scientific community.

1/
Authors choose every word carefully so it says exactly what they mean; technical words have precise meanings, and each one may refer to a whole field knowledge.

Here is a brief summary in non-technical language about what this paper says:

2/
The title states that during the two Feb. 6 big earthquakes in Turkey, the fault rupture traveled at different speeds on different parts of the faults - sometimes "sub-shear" and sometimes "super-shear."

They are comparing the rupture speed to the speed of shear waves.

3/
Read 18 tweets
Mar 13
These are the aftershocks that have occurred near Adana so far (map is tilted, N is to the top right).

Scary, right? But it's important to keep them in perspective - M4 events have happened many times near Adana, without leading to a giant earthquake.

How do I know?

1/
This is the earthquake record near Adana. I had to scale down the aftershocks to show it - they are small compared to to the recorded events!

Of course, a larger earthquake is possible; M6+ events have been recorded, and this fault could produce even larger earthquakes.

2/
The 1998 earthquake, at M6.3, was destructive - you can read more about it here.

3/

en.wikipedia.org/wiki/1998_Adan…
Read 6 tweets
Mar 12
At the western edge of the Mw7.8 Turkey-Syria earthquake there is a subduction zone: the Cyprus-Hatay Arc. This area was stressed by the earthquake, and has produced some aftershocks.

Should we worry about that?

1/
The Cyprus Arc is a subduction zone: the African plate is sinking beneath the Eurasian plate. Here, the rainbow lines show the depth to the main fault (the "megathrust") between the two plates.

2/
Seismicity recorded since Feb 6 shows several aftershocks along the eastern part of the arc.

So it seems that the stress from the earthquake sequence is indeed producing a response on this fault system.

3/
Read 19 tweets
Mar 11
A couple hours ago, there was a M4.2 earthquake near Adana.

This is not a large event, but it was widely felt. Although there have been many aftershocks of this magnitude, this is the largest to occur so close to Adana.

1/ Image
At this point there is no way to know what will happen. The most likely scenario is that there will be a few more smaller events. There could be more similar-magnitude events (M4-5). It is possible, though not likely, that there could be a larger event.

2/
In the map above I've included a new fault map. These are based on the new AFEAD database. In my map all the faults are all drawn in the same color, but they do not all pose the same hazard.

You can go to their website to learn more.

3/

neotec.ginras.ru/index/mapbox/d… Image
Read 4 tweets
Mar 11
How do we model the movement and deformation of tectonic plates?

When plates have clear edges, block models work pretty well. But in areas with distributed deformation they start to fall apart.

This paper looks like a promising new approach:

1/

agupubs.onlinelibrary.wiley.com/doi/full/10.10…
Block models treat each tectonic plate as rigid, and use GPS observations to calculate how that plate is moving.

At plate edges, this falls apart, because the regions around faults accumulate elastic strain - they bend and stretch.

2/

geology.wisc.edu/~chuck/MORVEL/…
But the reality is that "plate edges" are not so clearly defined. Zoom in on California, Iran, Turkey, Japan - and you will find many hundreds of faults that interact in complicated ways.

3/

en.wikipedia.org/wiki/Southern_…
Read 7 tweets
Mar 10
The fault near Kayseri is continuing to produce earthquakes that are almost M5.

These earthquakes are not very large, but this activity level is unusual for this part of the fault.

1/ Image
Although most moderate earthquakes are not a signal of future large events, some large earthquakes do have foreshocks. So it is good to pay attention to these events - they are telling us something about the faults in the area.

2/
The most likely scenario is that the area will experience aftershocks, getting smaller and less frequent over time.

However, with three events of similar magnitude already, more M4-5 events are possible.

There is also a small chance of a larger triggered event.

3/
Read 5 tweets

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