Agung Setianto1 and Ibrahim Djamaluddin2,

1Department of Geological Engineering, Gadjah Mada University, Indonesia

2Department of Environmental Engineering, Hasanuddin University, Indonesia

Modeling 3D Faults for Seismic Hazard

Assessment in GIS

Earthquake hazards...

Slope failures

A landslide triggered by an earthquake in Sichuan province, China;

2008

Seismic-induced fires

Buildings in flames as fire spreads by earthquake in Kobe,

Japan; 1995

Several well-known examples of destructive earthquakes have clearly shown that the local site conditions are an important factor

in determining the seismic hazard specific to a given site.

Structural damages

Nepal earthquake collapses buildings in

Kathmandu; 2015

Subsidence/settlements

Places were submerged under the sea surface, by Great Japan

Earthquake on April, 2011

Liquefaction

Liquefaction on Kilmore St., Newzealand by earthquake of 22 Feb

2011.

Flow of presentation Introduction to a Seismic Hazard Map

- Earthquake and seismic ground motion

- Types of earthquakes

- Types of seismic hazard maps

Seismic Hazard Maps for Specified Seismic Source 3D Faults

- Types of maps and related information

- Assessment methods

- Development of a GIS-based calculation system

Application

- Geological settings

- Historical seismicity

- Seismic hazard assessments

Earthquake and ground motion

An earthquake involves the shaking of the ground by vibrations caused by fault movements. The

characteristics of a seismic ground motion are depends on 3 factors:

1. source,

2. propagation, and

3. site condition.

The types of earthquakes

There are various types of earthquakes:

1. earthquakes on the plate boundary;

2. earthquakes within subducting (or subducted) plates; and

3. earthquakes occurring on active faults on land.

Types of seismic hazard maps

“Seismic Hazard Maps for Specified Seismic Source Faults” pay attention to

specific seismic source faults and indicate, the strong shaking of the

surrounding areas when an earthquake occurs.

1. conventional method, or

2. numerical simulation, such as FDM

"Probabilistic Seismic Hazard Maps” show the probability for a fixed time

period and intensity, and intensity for a fixed time period and probability.

1. probabilistic theory

Types of maps and related information

There are two types of "Seismic Hazard Map

for Specified Seismic Source Faults":

1. on the engineering bedrock, and

2. on the ground surface

Peak velocity on the engineering

bedrock

Peak velocity on the ground

surface

Seismic intensity on the

ground surface

Conventional method procedures

What is GIS?

Geoprocessing is a Python language consisting of operators, or tools, that operate on the data within

GIS, and perform tasks that are necessary for analyzing information across a wide range of disciplines.

What is Geoprocessing?

Development of an innovative assessment

system by GIS technology

applied Geoprocessing system to automatic computation of

the 3D geometric faults;

adopted the conventional method of seismic hazards to the

3D grid data calculation system; and

Customized calculation system interfaces tool.

GIS workflow process Peak velocity

eng. bedrock

Peak velocity

grd. surface

PGA

Seismic

intensity

Geology Lineaments 3D faults

Geomor-

fologic

Shear wave

Vs30

Amplifica-

tion factor

Grid data

system

3D fault process

3D seismic

analysis

Topography RS images

Input Process Output

Entire steps (110 processes)

1 step

Schematic workflows of geoprocessing

for automatic calculation of 3D faults

Example of input data

Dip 35

Dip 65

Fault line 1

Fault line 2

Integrated GIS interfaces

Interface for input data

Surface DEM (Raster

data)

Fault Line (Polyline

shapefile data)

Fault lines attributes

Depth of Fault

Fault Dip

Calculating interfaces

To be able calculation of many fault lines

by the iteration model

Result in 3D view

Result in 3D view

Developed seismic hazard system

Application to Beni suef, Egypt

The study area is located at the northern part of

Egypt as a part of the Nile Valley.

The study area is mostly covered by sedimentary

rocks of different formation as well characterized

by flat topography.

Generally, Egypt buildings are not designed

to resist earthquakes, therefore relatively small

events can be the source of huge disasters.

The earthquake of 12 October 1992 is well known example of a small but effecting

earthquake in Egypt. Local site effect conditions are directly related to significant damage and

loss of lives.

Geological conditions

A geologic map of the study area was

simplified from Egyptian General

Petroleum Corporation (1987), scale of

1:500,000

The area of Beni Suef is covered by

sedimentary rocks of different formations

belonging to the middle Eocene up to the

Quaternary.

Tectonic setting

The trend analysis of faults deduced from

geological and geophysical data around the

source area reflects the existence of two

dominant trends N60E and N45W (Abou

Elenean and Deif, 2003).

Based on analyzing the lineaments extracted

from geological map of EGPC (1987) in the

present study, it was observed that the prevailing

trends are dominantly in the NE-SW and

NW-SE, in correspondence with the previously

obtained trends deduced from geological map

and density map (Ammer, 1982).

Rose diagram

Relief map and lineaments

Shear wave velocity The shear wave velocity of shallow sediments is

very important in seismic wave amplification and

thus Vs30 is a well-known parameter for site

classification.

It has been recognized that soft and young

sediments covering firm bedrock can amplify

seismic waves and cause severe damage during a

large earthquake.

Qualitative estimation of susceptibility The areas where the soils consist of soft sediments

like loose sands and silty clay are more susceptible

to amplification.

It is obvious that lower shear wave velocities up to

400 m/s correspond quite well with the outcrop of

unconsolidated, Quaternary sediments in the study

area.

(Seed and Idriss 1982), mentioned that most soils

amplify peak acceleration where the hard ground

acceleration is less than 0.1g, where soft to

medium stiff clay and sand causing the largest

amplification.

Shear wave up to 400 m/s

Noted: (1.0g is approx. 980 cm/sec2 or 980 gals)

Recorded earthquake (1973~2010) around

study area by USGS

Study area

1992 Dahshour earthquake (5.9)

1999 Beni Suef earthquake (4.9)

3D faults and grid system in GIS

Scenario studies

Case 1: October 11, 1999 Beni Suef earthquake source

- magnitude 4.9,

- depth of epicenter 26km,

- fault depth to upper edge 15km,

- length of fault 5km, width of fault 12km, and

- fault orientation (strike153o and dip72o)

Case 2: October 12, 1992 Dahshour earthquake source

- magnitude 5.9,

- depth of epicenter 22km,

- fault depth to upper edge 12km,

- length of fault 12km, width of fault 10km, and

- fault orientation (strike 270o and dip47o)

Case 3: Case 2 with expected magnitude 6.5

Case 1: results

Case 1: results

Case 2: results

Case 2: results

Case 3: results

Case 3: results

Conclusion and Discussion Modeling 3D faults for seismic hazard assessment has been done in GIS. The

3D polygon as 3D fault layer was constructed automatically in GIS

geoprocessing process model by using a geometrical lines data. By 3D fault’s

shape and attribute data in the 3D polygon, GIS gives significant result for

the calculation of seismic hazard assessment in which the spatial data such as

3D fault layer, 3D topographical model can be applied in the GIS system

development.

Furthermore, seismic hazard assessment model for specified seismic source

faults as study case has been evaluated. The spatial ground motion of the

October 12, 1992 Dahshour earthquake with magnitude 5.9 and the

October 11, 1999 southeast Beni Suef with magnitude: 4.9 and maximum

expected parameters for earthquake source with magnitude 6.5 have been

simulated using the GIS developed system. The peak velocity on the

engineering bedrock, the peak velocity on the ground surface and the

seismic intensity on the ground surface are calculated.

Future research plan Seismic hazard maps

Geospatial maps

Disaster prevention and risk

reduction analysis