Earthquake in central Italy

[fausto]

http://www.bbc.com/news/world-europe-37171953

 

[Fabri91]

Here a figure depicting the border between the African and the European plaque, explaining why the area is so geologically active:

As can be seen the border essentially runs along the Appennini mountain chain, which itself runs along a large part of the Italian peninsula.

---------- Post added at 20:12 ---------- Previous post was at 20:09 ----------

At least 120 confirmed dead, for now.

---------- Post added 25-08-16 at 07:29 ---------- Previous post was 24-08-16 at 20:12 ----------

Up to 247 confirmed now, with many persons still missing.

There were also many aftershocks reported (around 60 in total), which in general had a significantly lower "energy content" than the main event.

 

[Urwumpe]

If you look at the low number of people who actually lived there before the Earthquake, the 247 deaths mean essentially, that every family lost somebody.

 

[Fabri91]

Absolutely. What is also a complication in estimating the number of casualties is that these very small towns are often important tourist destinations, which means that in any given moment in the holiday season the real population might be significantly higher than that of the official residents.

 

[Notebook]

http://www.esa.int/spaceinimages/Images/2016/08/Italy_earthquake_displacement

Description
Combining two Sentinel-1 radar scans from 20 August (Sentinel-1B) and 26 August 2016 (Sentinel-1A), this interferogram shows changes that occurred during the 24 August earthquake that struck central Italy.

The seven interferometric ‘fringes’ correspond to about 20 cm of surface deformation in the radar sensor line of sight. Each fringe (which is associated to a colour cycle) corresponds to approximately 2.8 cm of displacement.

Although Sentinel-1 has a swath width of 250 km over land surfaces, its pass over Italy on 26 August did not cover the entire area affected. Another acquisition planned for 27 August will cover the entire earthquake zone.

 

[Fabri91]

Number of confirmed dead appears to have settled on 291.

It is notable how the nearby town of Norcia escaped almost all damage after having had a major "earthquake-proofing" in the wake of the Acquila one five years ago, while in Amatrice a school that was supposedly renovated in 2012 failed at least partially. Luckily summer holidays are still underway.

 

[Notebook]

http://www.esa.int/Our_Activities/O..._provides_new_insight_into_Italy_s_earthquake

Scientists from Italy’s Institute for Electromagnetic Sensing of the Environment combined Sentinel-1 radar acquisitions over central Italy from before and after the 24 August 2016 earthquake: 15 August, 21 August and 27 August 2016. The result shows vertical ground subsidence, reaching about 20 cm in correspondence to the Accumoli area, and lateral movement of up to 16 cm. The blue line indicates the location of the fault trace.

 

[Fabri91]

If I heard the news correctly, the dead count for now is 292.

Let's hope that the reconstruction doesn't pan out like it did after the Aquila event where a the new houses turned out to be very shoddily built and subsequently abandoned.
It must be noted that that project was strongly advocated for by the Berlusconi government. This time around I'm slightly more optimistic, but we'll see how this pans out.

 

[Artlav]

It almost sounds like the area gets enough earthquakes to be damaged, but not enough to make people feel serious about preparing for them.

I lived in Chile for a few months, which is on the upper end of the scale.

A 3-4 quake happens almost every week. People don't really pay attention to them.
An 6+ like the Italian one can happen several times a year, and is generally a non-event. Some repairs are needed, and occasionally someone would die from a heart attack or bad luck.
An 8+ happens every decade or so.

The saying is that if a building is still standing, then it can take a magnitude 8.
In other words, people take the threat seriously.

What is it like in Italy?

 

[Fabri91]

It's...odd: these 6.something quakes happen essentially at most 1-2 times a decade. 8+ like in Japan are extremely rare.

This means that in some places things get reinforced/restructured accordingly, but historic city centers with many seriously old buildings remain vulnerable, since it would be technically possible but expensive to reinforce them, as done in Norcia, which almost didn't have any damage.

It must be noted however that new buildings must follow regulations to make them more or less quake-proof, but in part they might not be followed due to corruption/inertia, and provided they are followed obviously no news program will go and tell "here nothing happened", if you get my point.

 

[Urwumpe]

More so, if you look closer at the debris pictures, you can often easily see, that some concrete walls had been made of much more sand than cement. Pretty common fraud in the construction industry, not just in Italy, but fatal in an earthquake zone.

For example for the other places... my balcony proved a similar design when a surveyor tried to take a core sample from it to estimate the structural integrity and failed to take a single one that did not crumple already inside the drill. Looks like good concrete was rare in the German 1950s. (The structural integrity was questioned when removing the screed resulted in large holes and craters in the balconies here)