Seismic vulnerability in

Latinamerica

Speaker: Rafael Osiris de León

Sciences Academy of Dominican Republic.

IANAS GENERAL ASSEMBLY

Punta Cana, 16-20 July, 2013

TECTONIC PLATES

AND EARTHQUAKES

Pacific fire belt produces 80% of total eartquakes

Main regional faults in the Hispaniola Island

Main damages zone of the 2010 Haití earthquake

The 2010 Haiti earthquake

On January 12th, 2010, a 7.0 magnitude

earthquake with an epicenter 15 km SW

of the city of Port-au-Prince and a

hypocenter at 10 km depth, produced

316,000 deaths, 350,000 wounded, and

destroyed 300,000 homes that left

1,500,000 homeless. This is the worst

global seismic tragedy of the past 50

years.

Haiti national palace, raised on soft clay,

and destroyed by the 2010 earthquake.

Haiti national palace, raised on soft clay, and

destroyed by the 2010 earthquake.

Vs profile at North side of National Palace of Haití,

showing soft soils at surface that should be remove for

the construction of the new Palace.

Haiti Cathedral, raised on soft clay, and

destroyed by the 2010 earthquake.

Typical clay of the Port au Prince valley

The famous hotel Montana raised on different

materials with different seismic answers.

Small village, raised on soft clay, and

destroyed by the 2010 earthquake.

Salessian School, raised on soft clay

with 3 upper soft stories

destroyed by the 2010 Haití earthquake.

Building raised on soft clay

with first floor in columns, without shear wall.

The soft floor collapsed.

Bank raised on soft clay

with first floor in columns, without shear wall.

The soft floor collapsed.

Typical structure collapsed in 2010 Haiti EQ.

University of Leogane, with three floors collapsed

Leogane school raised on soft clay

and supported by columns failed by shear

strenght.

.

Leogane school raised on soft clay

and supported by columns failed by shear

strenght.

.

Vs profile at harbor East side, in Port au Prince, Haití,

showing soft soils between 2.0 and 4.5 m deep with a

Vs of 75 m/sec. The best choice is to remove this bad

material prior to start with the building foundations.

Vs profile at harbor East side, in Port au Prince, Haití,

showing soft soils between 2.0 and 4.5 m deep with a

Vs of 75 m/sec. Relating this low shear strength, we

would expect a site amplification of the EQ effects.

Structures on rock without damages

In the southern mountainous area of

Petionville, buildings did not suffer any

damage, although many buildings were

erected without any engineering

criteria, and although they were located

in or near the epicenter area, but as

they were raised on hard limestone

bedrock, all the bad structures were ok,

as a rock site protection effect.

Very hard limestone rock of south hills of

Port au Prince. Site protection effect.

Poorly built structures erected without any

engineering critera, without any type of

damage, not even cracks, after the earthquake.

Poorly built structures erected without any

engineering critera, without any type of damage,

not even cracks, after the earthquake.

Poorly built structure, with a second soft floor,

erected without any engineering critera,

without any type of damage after the earthquake

A dense village compound, on the hard

limestone rock of south hills of city.

Note the lack of damage.

The rich villages of PetionVille, without any type

of damage, not even cracks, after the earthquake.

The rich villages of PetionVille, without any

type of damage, not even cracks, after the

earthquake.

The 2010 Chilean earthquake

On February 27, 2010, 45 days after the

Haity earthquake, Chile was shaked by

on of the mayor earthquakes of the

world, with magnitude of 8.8, causing

452 deaths, mainly in the coastal line

where the sea water became as

tsunami.

Alto Río building Collapsed during Chile earthquake of 2010.

2010 Chile earthquake

2010 Chile earthquake

1960 Chile earthquake

In 1960 Chile was shaked by the

biggest earthquake registered, with a

magnitud of 9.5, producing a tsunami

that killed 61 peoples in Hawai and 200

peoples in Japan.

1939 Chile earthquake

On January 24, 1939, the city

of Chillán, Chile, was shaked by

a very strong earthquake, with

30,000 deaths.

1944 Argentina earthquake

On january 22 of 1944, the city

of San Juan, Argentina, was

shaked by one earthquake, with

a balance of 10,000 deaths.

El terremoto de Perú

One of the biggest earthquake

in Latinamerican countries was

on May 31, 1970, in Peru, with

75,000 deaths.

The 1972 Managua earthquake

On december 23, 1972,

Managua city, in Nicaragua,

was shaked by a strong

earthquake, killing 20,000

peoples.

The 1976 Guatemala earthquake

On February 4, 1976,

Guatemala city was shaked by

an earthquake, with 23,000

deaths.

The 1985 México earthquake On September 19, 1985, Mexico

city was shaked by an

earthquake with epicenter in

the Pacific coast, 320 Km away,

killing near 45,000 deaths in the

building raised over the

flexibles soils of the ancient

Texcoco lake.

The 1985 México earthquake

CONCLUSIONS

The 2010 earthquake of Port-au-Prince, located on the

southwestern area of the Hispaniola island, was the

most devastating earthquake in the island’s history, and

this disaster was particularly extensive as the epicenter

was close to a dense and poor urban area raised over

low-shear strength clay and sand soils.

Propagation velocities of shear seismic waves (Vs) on

the east side of the Port au Prince harbor, shows that a

horizon from 1.3 m to 4.5 meters deep has a shear-wave

velocity (Vs) of approximately 75 meters per second.

This material has low shear-strength, and therefore,

would cause amplification of strong ground motion.

CONCLUSIONS

In the southern mountainous area of Pétionville, where limestone bedrock is present at the surface, the buildings did not suffer any type of damage, not even cracks, in the poorly built structures erected without any engineering forethought.

Soil characteristics should relate to building criteria

designed to combat amplification, etc. For example,

isolated columns in use on top of soft soils, must be

increased in diameter to handle greater shear

deformation. This applies to all buildings, but

particularly to the construction of schools, hospitals,

towers, malls, and service and strategic institutions.

CONCLUSIONS

Future engineering seismic design

must be in accordance with shear-

wave velocity measurements made

at building site to avoid or reduce

disasters, as seen in Haiti, Mexico,

and other Latinamerican countries.

Thank you for your attention.