5th Swiss Geoscience Meeting, Geneva 2007
Elements for Improving Loss Estimates in real-time:
Microzonation of soil conditions in Important Cities
Worldwide
Rosset Philippe*, Wyss Max*, Kaestli Philipp** & Wiemer Stephan**
* World Agency of Planetary Monitoring and Earthquake Risk Reduction, rue de
Jargonnant 2, CH-1207 Genève (rosset_p@wapmerr.org)
** Swiss Seismological Service, ETH-Hoenggerberg, 8093 Zuerich
For the last four years, we have estimated the extent of disasters within less
than one hour for earthquakes worldwide (Wyss, 2004). For these 300 cases,
we used approximate methods because details on many of the parameters
needed are generally poorly known in developing countries, the focus of our
efforts. Now we are engaged in a collaborative project between WAPMERR
and the Swiss Seismological Service to construct a new computer program and
world-database (QUAKELOSS 2) to take our capability to estimate losses to the
next higher level. We will still have to rely on averaging losses over tens of
thousands of buildings, but we are now modeling important cities by districts.
Loss estimates we compute contain the following information. A map showing
the average degree of damage in settlements near the epicenter, a list of the
casualties in these settlements, the total number of fatalities and the total
number of injured. The new database will include information on the following
parameters. (1) Up-to-date population numbers. (2) New fragility curves for
building resistance to strong ground motions. (3) Information on number and
type of buildings from satellite images. (4) Locations of landslide prone slopes.
(5) Locations of airports. (6) Regional attenuation relationships of seismic
waves. (7) Information on soil conditions in important cities, especially
microzonation data.
We are modeling large cities as consisting of a number of districts according to
administrative boundaries within which the population number is known and
according to soil conditions. The latter information may range from a simple
geological map to detailed microzonation with amplification factors for strong
ground motions. Currently, our database contains information for about 50
cities, distributed over the globe (Figure 1). We rank the quality of information
in terms of “usefulness” of the map for the database (poor, moderate, good,
very good). It informs on the pertinence of the data provided (coordinates, local
ground motion parameters, applied methods) and other available data. The
next step consists in designing a procedure to derive amplification factors from
the various information collected.
Pilot cities, as Tehran, or countries, as Peru, will be selected to apply the
procedure. The cities will be divided into districts with a specific coefficient of
site amplification based on the referenced microzonation map. Scenarios will
be computed and compared to damage in past earthquakes.
5th Swiss Geoscience Meeting, Geneva 2007
Figure 1. Location of cities where microzonation maps are already compiled and
analyzed. The indicator of usefulness give insight into the pertinence of
collected data.
WAPMERR estimated the likely losses in future earthquakes in the Himalaya in
the March 2005 issue of the journal Natural Hazards (Wyss, 2005). In this
article a scenario called Kashmir anticipated between 76,000 and 137,000
fatalities in a hypothetical future earthquake in that region. In October, 2005, an
earthquake of magnitude 7.6 hit Pakistani Kashmir, killing about 85,000 people.
The Kashmir scenario was a scientific success but not translate into action for
mitigation. The development of the new databases will help to improve loss
estimates scenario as a tool to prepare for future damaging earthquakes around
the world.
REFERENCES
Wyss , M. 2004. Real-time prediction of earthquake casualties, paper presented
at International Conference on Disasters and Society – From Hazard
Assessment to Risk Reduction, edited by D. Malzahn and T. Plapp, Logos
Publishers, 165-173, Univ. Karlsruhe.
Wyss , M. 2005. Human losses expected in Himalayan earthquakes Natural
Hazards , 34 , 305-314.
AKNOWLEDGMENTS
Elena Nikolaeva and Mikheil Elashvili from the Seismic Monitoring Center of
Georgia in Tbilissi collaborate with us in the compilation of data. This work was
5th Swiss Geoscience Meeting, Geneva 2007
carried out with the support of the Swiss Agency for Development and
Cooperation, but does not necessarily reflect the opinion of this agency.