Schmitz etal 2013 AGU Cancun Microzoning Caracas

Schmitz etal 2013 AGU Cancun Microzoning Caracas

NH51F-06. AGU 2013,
Meeting of the Americas.
Implementation of seismic microzonation in municipality
ordinances in Caracas, Venezuela
Michael Schmitz, FUNVISIS, [email protected], Florian Olbrich, FUNVISIS,
Gustavo Coronel, IMME-UCV, Cecilio Morales, FUNVISIS, Ketty Mendes, FUNVISIS,
Roberto Uzcátegui, FUNVISIS, Maxlimer Vallée, FUNVISIS,
Arisbel Arreaza, Libertador Municipality, Caracas
1. Abstract
Strong site effects, which caused the collapse of 4 buildings with 10 and more
storeys during the Caracas 1967 earthquake, and the damage of a big number of
them in the same deep sediment area, motivated the development of the Caracas
Seismic microzoning project in the years 2005-2009. The main results of this project
were the development of design response spectra for the different microzones
within the sedimentary basin, as well as estimates of landslide hazard.
Implementation of the results in municipality ordinances is actually discussed with
local authorities. They are aimed to address mitigation for new constructions by the
application of the specific design spectra, for existing buildings via evaluation and
retrofitting strategies, and for slope areas (informal, as well as formal
developments) due to the identification of areas that may not be developed or
require detailed studies of slope stabilities.
5. Seismic microzones and adjustment to cadastral limits
8. Use of microzoning results in municipality ordinances
As a result from geological, geophysical and seismic engineering studies, a
seismic microzoning map was derived, which allows to define zones of similar
seismic behaviour within the city (Schmitz et al., 2011)
Since 2011, after finishing the Caracas seismic microzoning study, considerations
for the implementation of the results have been discussed with Libertador
municipality, and since 2012 also with the other municipalities Chacao, Sucre,
Baruta and El Hatillo. Results maybe used for new buildings in complement of the
building code, as well as for existing buildings and hillsides, within existing laws
and technical regulations.
Marco Legal
• Ley
Orgánica de Ordenación
Urbanística (Gaceta Oficial Nº
33.868 del 16 de diciembre de
1987) y su respectivo Reglamento
extraordinario (Gaceta Oficial Nº
4.175 del 30 de Marzo de 1990) .
• La Ley de Gestión Integral de
Riesgos
Socionaturales
y
Tecnológicos (Gaceta Oficial Nº
39.095 del 9 de enero de 2009).
2. Seismic hazard
Marco Técnico
•
Norma Técnica Nacional para
Edificaciones
Sismorresistentes
COVENIN 1756-2001 (COVENIN,
2001)
•
Resultados del Proyecto de
Microzonificación
Sísmica
de
Caracas (FUNVISIS, 2009, Schmitz
et al., 2011)
In 1967, 4 modern high-rise buildings collapsed and more than 200 were damaged
in a distinct area of the city, characterized by deep sediments.
9. Libertador municipality
Priorities for detailed building evaluation and possible retrofitting are defined
based on the parametric studies of building behaviour (Hernandez, 2009), as well
as for the school buildings, based on a detailed study, including retrofitting plans
for typical buildings (Lopez et al., 2007).
Seismic microzones were adjusted to the cadastral limits in each of the
municipalities in order to avoid ambiguities for the application of the elastic
response spectra (Hernandez et al., 2011)
The main seismic hazard is attributed to the San Sebastian fault system, which
marks the plate boundary between the Caribbean and South America plates, is
located just 5 km north of the city. Simulations of seismic hazard show decrease
from north to south, with amplifications in the sedimentary basin, as for example
for a severe scenario like the 1812 earthquake (Yamazaki et al., 2005).
6. Landslide hazard
A fast growing part of the city with more than half of its population comprises
informal housing at steep hillsides surrounding the valley with earthquake or
rainfall triggered landslide as the principal hazard in these areas. Therefore, a
methodology for the evaluation of the susceptibility to mass movements, including
local calibrations, was applied (Hernández et al., 2008).
3. Caracas today
10. El Hatillo municipality
Caracas is a city of more than 3.5 million inhabitants. High-rise buildings prevail
within the sedimentary valley, and informal buildings with up to 6 storeys cover
most of the surrounding slopes. 5 municipalities compose the Caracas
Metropolitan Region.
El Hatillo municipality is located in the hilly south eastern part of Caracas
Metropolitan Region, with few contribution of sedimentary areas, but predominant
bedrock and weathered bedrock with moderate landslide hazard.
Recommendations are given how to treat areas of high landslide hazard, and how
to calculate the affected slope areas, as well as indications for response spectra
that take into account topographic effects at hillsides.
11. Chacao municipality
Chacao is the business district of Caracas with high-rise buildings in the area
affected by the 1967 earthquake. The Local Urban Development Plan PDUL is
actually in discussion and restrictions to building heights were introduces in areas
of high sediment thickness in order to mitigate seismic risk to high-rise buildings.
4. Subsurface investigations
A series of geophysical measurements, including seismic refraction, noise
measurements and gravimetric modelling, together with geological (drillings, quaternary
geology) and geotechnical investigations led to a detailed subsurface model. Information
of sedimentary thickness (Amaris et al., 2011) was used for modelling of the seismic
response within the valley in 2-D and 3-D configurations.
7. Active faults
Corridors are defined around the outcrops of the active Tacagua – El Avila fault
on the northern limit of the Caracas valley. Detailed neotectonic investigations are
required for construction permits within this corridor.
12. References
Amarís, E., Schmitz, M., Murphy, V., 2011. Sediment thickness as primary input for the Caracas Seismic Microzoning Project.
5th International Conference on Earthquake Geotechnical Engineering, Santiago de Chile, Paper Nr. MOSAM, 12 pp.
Hernández, J.J., 2009. Confiabilidad sísmica-estructural de edificaciones existentes de Caracas. Proyecto Pensar en
Venezuela, C.I.V., Jornadas 18 y 19 de septiembre de 2009. Memorias, 115 pp.
Hernández, J.J., Schmitz, M., Delavaud, É., Cadet, H., Domínguez, J., 2011. Espectros de respuesta sísmica en microzonas de
Caracas considerando efectos de sitio 1D, 2D Y 3D. Revista de la Facultad de Ingeniería UCV, 26 (2), 49–66.
López, O.A., Hernández, J.J., Del Re, G., Puig, J., Espinosa, L., 2007. Reducing Seismic Risk of School Buildings in
Venezuela. Earthquake Spectra, 23 (4), 771–790.
Schmitz, M., Hernández, J.J., Morales, C., Domínguez, J., Rocabado, V., Valleé, M., Tagliaferro, M., Delavaud, É., Singer, A.,
Amarís, E., Molina, D., González, M., Leal, V. y el grupo de trabajo del proyecto de Microzonificación Sísmica de Caracas,
2011. Principales resultados y recomendaciones del proyecto de microzonificación sísmica en Caracas. Revista de la Facultad
de Ingeniería UCV, 26 (2), 113–127.
Yamazaki, Y., Audemard, F., Altez, R., Hernández, J., Orihuela, N., Safina, S., Schmitz, M., Tanaka, I., Kagawa H., and JICA
Study Team -Earthquake Disaster Group, 2005. Estimation of the seismic intensity in Caracas during the 1812 earthquake
using seismic microzonation methodology. Revista Geográfica Venezolana, Número Especial 2005, 199-216.