Earthquake footage shows Turkey's buildings collapsing like pancakes. An expert explains why [SEC=OFFICIAL]

[Trevor Allen]

Dear colleagues,

 

The tragic events that are unfolding in Türkiye and Syria over the past two days are a sobering reminder of the impact large plate-boundary earthquakes can have on the built environment and highlight the importance of modern building codes and compliance with them.

 

Below is a link to an article in the Conversation penned by Mark Quigley summarising the earthquake history of the region and advocating for the compliance of strong building codes to mitigate the impact of future tragedies.

 

https://theconversation.com/earthquake-footage-shows-turkeys-buildings-collapsing-like-pancakes-an-expert-explains-why-199389

 

Cheers,

Trevor

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[Kevin McCue]

Turkey has a modern earthquake code but it is not implemented.

Nor is ours. 

If you think your home, local office, hospital have been designed and constructed to resist earthquakes - think again. 

Kevin

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[Chris Burton]

Hi Kevin

AS 1170.4 is required under the NCC if I recall correctly, but agree, it's not required for sole occupancy dwellings

regards

Chris Burton FIEAust (retired)

P:  0417 848 619   E: chris....@adelaide.edu.au

On 8 Feb 2023, at 08:54, Kevin McCue <mccue...@gmail.com> wrote:

 Turkey has a modern earthquake code but it is not implemented.

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[Richard Weller]

Hi,

Of course, our code now requires engineered buildings to be designed for EQ. Domestic housing is generally exempt as it is designed for wind loads that are larger. In high EQ zones, domestic buildings need to be designed for a simplified EQ of 10% lateral force.

What is the problem for Australia, is that we have a lot of older buildings that are not designed for EQ simply because they are too old or of a style of building that is vulnerable - e.g. multi-story masonry (significantly tightened up in the 2007 standard) and soft story buildings (poorly braced ground floor for example).

We have had so few large EQs around our major cities that we are complacent of the risk. We also know very little about the EQ risk in Australia because we are intra-plate conditions and have only been here a couple of centuries.

Regards,

Richard

Richard WELLER
GOSFORD            (BE, MIEAust, CPEng, NER, IntPE(Aus))

0421 059 279

=========.=

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[James Daniell]

Dear all, 

Is definitely an intriguing sequence of events, which is likely not yet over.

Unfortunately looks like it will be upwards of 30k+ deaths (median estimate as of late 06.02.2023) and tens of billions of $ damage.

A number of colleagues are on the ground now, but yes, the spectral accelerations and velocities (PGV>100cm/s) especially down toward Hatay; as well as the mish-mash of different events mean that it is very complex to model the damage but we are working hard with all 3 governments currently to get out estimates. 

Just some food for thought in terms of the ground motions seen even from PGA.... and the fact that the ground motions exceed 0.1g from one of the 5+ events across many of the stations....

In addition a quick diagram of where this earthquake fits over time fatality-wise: https://www.datawrapper.de/_/pydN1/ 

Anyway better get back to it.... hope that you are all well, and stay safe for those who have to head there.

Cheers,

James.

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[Kevin McCue]

Thanks James for that snippet of information about the strong ground shaking shaking up to 0.88g for perhaps many tens of seconds.

In the interests of learning about these earthquakes let me share the following:

Ambraseys (1989) wrote about the East Anatolian Fault Zone: 

The Border Zone that is the contact of the Arabian plate with the three plates of Turkey, Eurasia and Iran to the north has been remarkably aseismic during this century. By extending the period of observation backwards in time by a few centuries it is shown that this seismicity is atypical of the long-term behaviour of the zone and due to a quiescent period in the activity of the area during the 20th Century. In turn, this implies that short-term data alone do not provide a reliable assessment of earthquake hazard.

He goes on to say that:

The East Anatolian Fault is clearly sinistral ….. and the deformations associated with earthquakes in this zone seem to occur along the entire length every few hundred years during relatively short paroxysmal periods of large events…….. the first paroxysm in our period of observations ended in 1544 and the second started after two and a half centuries of relative quiescence in 1789……. between 1789 and 1905, a series of relatively large earthquakes began, alternating between the two ends and gradually converging to the middle of the East Anatolian Fault zone…..

Almost all of the few cases that allude to faulting, i.e. in 1822, 1872, 1874 and1905, are for events in this 100km wide zone that shows remarkably low background seismicity, not only during this century but also in earlier times.

On 8 Feb 2023, at 14:01, James Daniell <j.e.d...@gmail.com> wrote:

Dear all, 

Is definitely an intriguing sequence of events, which is likely not yet over.

Unfortunately looks like it will be upwards of 30k+ deaths (median estimate as of late 06.02.2023) and tens of billions of $ damage.

A number of colleagues are on the ground now, but yes, the spectral accelerations and velocities (PGV>100cm/s) especially down toward Hatay; as well as the mish-mash of different events mean that it is very complex to model the damage but we are working hard with all 3 governments currently to get out estimates. 

Just some food for thought in terms of the ground motions seen even from PGA.... and the fact that the ground motions exceed 0.1g from one of the 5+ events across many of the stations....

<1stQuake.png><2ndQuake.png>

<image.png>

In addition a quick diagram of where this earthquake fits over time fatality-wise: https://www.datawrapper.de/_/pydN1/ 

To view this discussion on the web visit https://groups.google.com/d/msgid/aeesorg/CAOExgo8DekvB2DZ%2Bb22B5U_Vd74cP6YG1ZWW1a%2BPZg6UfvKbdA%40mail.gmail.com.