Morelia2012 workshop – Wed, 21 November

Good morning y ¡buenos días! from Mexico. The second day with scientific sessions is about to start, and after a fuerte breakfast with beans, tortillas, fruits and Mexican coffee we will move to the Centro Cultural Universitario to listen to the talks. The first morning session will focus on Seismic Hazard: Applications, Engineering and Critical Facilities. The second session is dedicated to Archaeoseismology. In the afternoon, an excursion to the historic city center of Morelia will deal with anti-seismic structures in buildings.

Again, we will try to update today as often as possible.

Morelia, Av. Francisco I. Madero Poniente

One of the countless beautiful churches of Morelia

 

Seismic Hazard: Applications, Engineering and Critical Facilities

The first talk was a key note by Ramón Zuñiga about the incorporation of paleoseismological data in a seismic hazard analysis. This was a great opening, especially since he decided to take Central Mexico as an example. We really need to think about how our data and findings will be used for hazard analyses in future.

The following talk was about active faults in Morelia and ground subsidence (Jorge Avila Olivera). Then, Iván Suñé-Puchol presented first results from the analogue modelling of a volcano sitting on a fault. Iván: We expect some great YouTube videos from you, soon!

Niklas Mörner discussed the attempts to store nuclear waste in Sweden and Finland. The waste needs to be kept safe for 100,000 to 1,000,000 years. After the melting of the last glaciers following the ice age, Fennoscandia experienced tremendous uplift and a number of magnitude 8 events and several of magnitude 7, as well as countless earthquakes of M6. How can we say this won’t happen again within the next 100,000 years?

Archaeoseismology

After the coffee break the archaeoseismology session was opened by our Spanish Colleagues Jorge Giner-Robles and Miguel Rodríguez-Pascua. They presented a review of orientated fall structures in instrumentally recorded earthquakes (Christchurch, Lorca, and Emilia Romana). Later, Raúl Pérez-López discussed the orientation of earthquake damage in relation to the seismic source, using the Emilia Romana example. This is just amazing – we clearly see an orientation in the damage pattern, independent of slope angles. This is true for toppled columns and monuments, toppled walls, cracks in masonry etc. What is the physics behind this phenomenon? Which wave causes the directivity effect? How does this apply on strike-slip, normal and thrust faults? Is there a relation to groundwater, lithology, sediment thickness, building material? What about hanging wall vs. foot wall? So many questions still to be answered.

Laura Alfonsi from Italy presented phantastic archaeoseismological data from Jordan – neolithic earthquakes that ruptured a skeleton, leaving it apparently beheaded. Really. I’ve never seen something like this before.

Victor Hugo Garduño-Monroy talked about archaeoseismology in the Mitla, Oaxaca area and raised the question whether a giant rock avalanche could have buried ancient monuments.

Klaus then discussed damage buildings and their use as seismoscopes. He told the audience to interpret any findings very critically and presented some examples of slow deformation that might easily be confused with earthquake damage.

Archaeoseismological excursion

The scientific part of the day ended with an excursion to the historical center of Morelia. Jorge, Victor, Miguel and Raúl lead us to see interlocked blocks in many of the monumental buildings and discussed whether these features can be interpreted as antiseismic measures. Here are some examples:

Interlocked blocks – antiseismic measures?

 

An interlocked keystone in an arch

 

The excursion group

And if you’ve ever asked yourself if we had good music here in Mexico, here’s the answer:

 

Who was it?

Christoph Grützner
works at the Neotectonics and Natural Hazards Group, RWTH Aachen University, Germany. He likes the Mediterranean and uses geophysics to search for ancient earthquakes.