this presentation was prepared for academic purpose. this is a summary of the paper,' Seismic Hazard Maps for Haiti' by Arthur Frankel et. al

3. Introduction
• In response to the urgent need for earthquake-hazard information after
the tragic disaster caused by the moment magnitude (M) 7.0 January
12, 2010, earthquake, seismologists felt the importance of constructing
initial probabilistic seismic hazard maps for Haiti to help the country's
rebuilding effort.
• In this article, they have documented their prepared hazard maps and
the procedure they have followed to prepare the maps.
• They have briefly showed the methodology for the seismic hazard
calculation
• Also, they discussed about their limitations and future scope to
improve the maps.

4. Focus of the study
• producing probabilistic seismic hazard maps that include the data
from the region's major faults and subduction zones where tectonic
plates collide and background earthquakes.
• developing a comprehensive catalog of active faults for the region.
• establishing scientifically defensible building codes for use in the
rebuilding process through the maps.

5. On January 12, 2010, a devastating earthquake with a magnitude of 7.3 struck Haiti,
near Port au Prince which was quickly followed by two strong aftershocks of 5.9
and 5.5 magnitude, resulting in an immense humanitarian crisis. The massive
earthquake, the biggest the region had seen in 200 years. This earthquake,
• left more than 1.5 million people homeless, and
• killed more than 220,000 people and over 300,000 were injured.
• badly damaged over 188,383 houses and 105,000 were destroyed by the
earthquake.
• 60% of Government and administrative buildings, 80% of schools in Port-au-
Prince and 60% of schools in the South and West Departments were destroyed or
damaged.

6. • Assessment of seismic hazards require background of historical
earthquakes of that specific region and the designation of active
faults or earthquake sources in the region.
• Three crustal faults were considered explicitly in the hazard maps:
the Enriquillo-Plantain Garden and Septentrional strike-slip faults
and the Matheux-Neiba thrust fault.

7. Haiti's quake history from 1900-2010. The depths and magnitudes are indicated.
Credit: USGS
Background history of earthquakes in Haiti

8. Major crustal faults
Map of crustal faults (red and green) and subduction zones (blue) used in the hazard
calculations.

9. Methodology for hazard calculation
• Followed the basic probabilistic methodology
• Calculated seismic hazard curves
• Modeled seismic sources include gridded historical seismicity,
subduction-interface zones and major crustal faults with known slip
rates
• Combined the hazard from specific faults and subduction zones with
the spatially smoothed seismicity

10. Inputs to hazard calculation
Crustal faults:
• The seismic hazard from the crustal faults is determined from slip
rates derived from GPS measurements, with the rates of historic
large earthquakes as constraints.
• Hazard from the Enriquillo-Plantain Garden, Septentrional, and
Matheux-Neiba fault zones was estimated.

12. Attenuation relationship:
• Different sets of attenuation relations were applied
• attenuation relations were based directly on observations from a
global collection of large earthquakes
• Used to fit the peak ground accelerations (PGA) and spectral
accelerations.

13. Results of the study
• Results are presented as maps of peak ground acceleration and 0.2- and
1.0-second spectral response acceleration for 2% and 10% probabilities
of exceedance in 50 years
• Two sets of hazard maps were constructed
• One for a firm-rock site condition with a VS30 of 760 m/s.
• Another for a grid of shallow shear-wave velocities estimated from
topographic slope.

14. HAZARD MAPS FOR FIRM ROCK SITES
Hazard map of PGA (%g) with 10% probability
of exceedance in 50 years, for a
firm-rock site condition.
Hazard map of PGA (%g) with 2% probability of
exceedance in 50 years, for a firmrock
site condition.

15. HAZARD MAPS WITH SOIL AMPLIFICATION
Hazard maps using grid of VS30 values shown in Figure 7: (top) PGA (%g) with 10%
probability of exceedance, (bottom) PGA (%g) with 2% probability of exceedance in 50 years.

16. • The maps include data from the region's major faults and subduction
zones where tectonic plates collide.
• The scientists measured how fast these seismically active areas are
moving and estimated how often earthquakes will strike and how
much shaking will occur when a quake hits again.
• The highest hazards in Haiti are along the Enriquillo-Plantain Garden
fault and the Septentrional fault.
• The western end of the Muertos Trough is also a high-risk zone,
according to the maps.
• The big faults are the most likely hazardous, but substantial seismic
hazards spread throughout Haiti, and there are other faults that
seismologists still know little about.

18. Uses of the maps
• The initial seismic hazard maps should be considered for urban
planning and building design applications as the reconstruction of
Haiti progresses.
• could be used together with maps of local soil conditions
• can be used as the scientific basis for new building codes in the
country.

19. Limitations
• lack of information on faults.
• many assumptions have taken.
• do not consider all the sources of earthquake hazard
• these maps are incomplete for the Dominican Republic and eastern
Cuba
• Except the three fault zones the other fault zones in Haiti and the
Dominican Republic are not explicitly included in the hazard
assessment.

20. Concluding remarks
• In response to the urgent need for earthquake-hazard information,
seismologists have constructed initial probabilistic seismic hazard
maps for Haiti.
• Probabilistic seismic hazard maps are essential tools that help to
mitigate the loss of life and property from future earthquakes
• also provide important information for emergency response and
preparedness, planning, decision-making, and hazard awareness
• The hazard maps can be used as the scientific basis for new building
codes in the country.

21. • These maps are based on the current information on fault slip rates
and historical and instrumental seismicity.
• There is a need to revise and improve these maps as more data
become available
• there's a lot of uncertainly so the faults deserve more study to better
resolve its slip rate, identify its paleo earthquake chronology, and
improve assessment of its hazard
• Much more geologic and geophysical field work needs to be done
for improving these initial maps.