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Urban Habitat Constructions under Catastrophic EventsFINAL CONFERENCE. Naples, 16th- 18th September 2010Chair of the Action: Federico Mazzolani, IT, [email protected] Science Officer: Thierry Goger, [email protected]
COST Action C26
FIRST CONSIDERATIONS ON THE FEBRUARY 27, 2010 CHILEAN EARTHQUAKE
Maurizio Indirli (1), Federico Mazzolani (2), Antonio Tralli (3)
(1) ENEA Bologna, Italy; (2) University of Naples “Federico II”, Italy; (2) University of Ferrara, Italy
About a month after the February 27, 2010 Chilean seismic event, an Italian investigation mission visited the area damaged by the earthquake and tsunami.
The team surveyed various building typologies (reinforced concrete, steel, masonry, adobe, etc.) from North to South towards the epicenter, i.e. the cities of Santiago, Viña del Mar, Valparaiso, Rancagua, Curico, Talca, Chillan, Concepcion, Talcahuano, Yumbel, Lota Alto, Schwager, etc.
All the coastal line from Talcahuano to Constitucion has been also ran through, in order to check the very impressive tsunami effects.
The behaviour of some Chilean historic buildings has been briefly evaluated, in comparison with similar ones hit by the April 2009, L’Aquila earthquake.
Figure 1. Subduction between Nazca-South American plates.
Figure 2a. Subduction activated fronts in the
Chile historic seismicity.
Figure 2b. Main shock (star), aftershocks (yellow
circles) and historic seismicity (red circles).
Figure 4. Tsunami wave heights along the Chilean coast.
Figure 3. Map of the investigated cities.
Chile is one of the most earthquake-prone country in the
world, struck by the most powerful seismic events ever
recorded (1960 Valdivia, MW 9.5).
Figure 5. Collapse and global overturning of the Alto Rio building in Concepcion.
Figure 6. O’Higgins building partial collapse in Concepcion.
Figure 7. Soft storey mechanisms in the Don Luis and Don Tristan buildings, Maipu (Santiago).
Figure 9. Sol Oriente building local damage (Santiago).
Figure 10. Park Plaza building local damage (Santiago).
Figure 8. Damage in the Festival (up), Rio Imperial (center) and other buildings
(down) in Viña del Mar.
In general, modern structures (r.c. and steel)
performed well, proving the effectiveness of the Chilean
seismic code, design and construction details.
Only a few of them, widespread in the affected
areas, showed damage or collapse, due to specific
reasons still under investigation.
Figure 11. Santiago, The Divina Providencia Church.
Figure 12. Santiago, The El Salvador Church.
Figure 13. Valparaiso, The Doce Apostoles Church.
Figure 14. Rancagua, The Catedral Church.
Figure 15. Rancagua, The San Francisco Church.
Figure 16. Talca, The Maria Ausiliadora Church.
Figure 17. Talca, The Corazon de Maria Church.
Figure 18. Yumbel, The San Sebastian Church.
Figure 19. Schwager, The Jesus Obrero Church.
Figure 20. Constitucion, The Catedral Church. Fig
ure
21
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Historic buildings (masonry, timber, adobe, and sometimes with other additional materials) suffered evident damages, getting heavier towards the epicenter,
also remarkable in cities far from it, as Santiago and Valparaiso.
Figure 25. Different types of adobe structure.
Valparaiso and Viña del Mar
Rancagua
Curico
Talca
Cobquecura
The historic centers showed an overall damage in the adobe
constructions.
This category includes a huge variety of structural elements
(timber, brick and stone masonry, pure earth, other materials, often
mixed together) with different resistance to horizontal loads,
and rare presence of strengthening devices.
The tsunami has been impressive, (wave heights until 12m and parallel to the coastal line).
It destroyed almost completely several fishermen and touristic
villages, but also parts of towns as Talcahuano and Constitucion.
The water run-up, coming in until 10 km inside the land,
was responsible of almost one half of the casualties.
A comparison between L’Aquila and Chile seismic events
can be done.
Even if the gap in dimension (450x200 vs 26x11 km, almost
20 times more), magnitude (8.8 vs 6.3) and duration (150s vs 15s, ten
times more) is enormous, the Max Intensity reached in Abruzzo was higher
(X vs IX).
Figure 23. Courtesy of Rodolfo Saragoni
Talca
L’Aquila
out-of-plane collapse mechanisms
L’AquilaCurico
in-of-plane collapse mechanisms
L’Aquila
Talca
roof-pushing mechanisms
Valparaiso: in-plane
Constitucion: out-of-plane
A debated question in Chile is how to avoid the complete demolition of this still remaining construction, unable to withstand strong earthquakes, but testimony
of history and culture. Figure 24. Damages in L’Aquila and Chile
Figure 22. Tsunami damage
