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Proceedings, XXth congress

A. Garagon Dogru* *, T. Selcuk 5, H. Ozener“, O. Gurkan* , G. Toz“
* BU, Kandilli Observatory and Earthquake Research Institute, Geodesy Department, Cengelkoy Istanbul, Turkey -
(garagon, ozener, gurkano)@boun.edu.tr
® Turkish Land Forces Command, Ankara, Turkey - tselcuk@kkk.tsk.mil.tr
“ITU, Civil Engineering Faculty, 34469 Maslak Istanbul, Turkey - tozg@itu.edu.tr
YF (Youth Forum Session)
KEY WORDS: Earthquakes, GIS, Internet/ Web, Retrieval, Programming, On-line, Web based
The Internet has been changing the access and transmission of GIS data, applications and visualizations. Online GIS combines the
advantages of both GIS and the Internet. Geographic information can be distributed in a variety of forms on the Internet. Moreover
as the Internet technology takes progress, web-based GIS applications also change. This paper focuses on development and
implementation of a web-based GIS application for earthquake information. In this study, a dynamic map browser type of web-
mapping applications was designed for interacting with the earthquake information. This method provides users easy access to GIS
data and basic functions on the Internet with low technological requirements. The user is not required to learn anything beyond the
basics about how to interact with the system as well. In the study, a GIS application and a web site was developed to serve the
system on the Internet. By integrating various data from different sources, this study aims to provide public users can access
information about: earthquakes doing spatial and attribute query. Furthermore this model enables easy data management including
maintenance and updating.
1.1 Internet GIS
Geographic Information Systems (GIS) are tools for acquiring,
managing, analyzing, and presenting spatially related
information (Coors, 1998). GIS convert diverse data into easy-
to-read and easy-to-access maps and information. In addition,
the advantages of the world wide web are numerous, the two
primary being time independence and spatial independence
(Mohler and Duff, 1999). Distributing data over the Internet is
more efficient than transmitting data through disks. Both
Internet and GIS changed the processes of accessing, sharing,
disseminating and analyzing data. Technology to share GIS
data, such as Web GIS, Open GIS and Distributed GIS on the
Internet is rapidly progressing (Honda, 2003).
1.2 Approaches to Internet GIS
Internet GIS includes any application that uses the Internet
technology to make geographic data available. Geographic
information can be distributed in a variety of forms on the
Internet. There are several basic approaches to transmit
geographic data (Garagon, 2002). The first is raw data
download. If the user has GIS software capability, he/she will
not request finished maps. After the data sets have been put on
the user’s local disk, the GIS work is done off-line. Maps is the
most common way of distributing geographic information.
Maps may be static with a predesigned symbology or may be
dynamic where the map itself or the viewing perspective of it
can changed by the user, such as with a zoom-in/out feature for
seeing a region of particular interest (Selcuk, 2001). Simple
searches are also performed in a database according to a set of

* Corresponding author.
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criteria. These criterias can be either spatial or thematic. The
records that match the criteria are then returned to the user,
either in a map or a text report format. In another type of
distribution, users can perform complex multi-theme queries,
create buffers and customized maps, perform statistical spatial
analysis, and so on. It allows users to create new data sets
without altering the data.
For designing web-based GIS applications, variety of programs
and forms are available. But the web applications are based on
the same model called client/server (Plewe, 1997) (Figure 1).
The client makes a request to a server. The server processes the
request and returns the information to the client. In this model,
the process is shared between the client and the server, with
different ratios. This sharing process is generated in various
forms which have advantages and disadvantages. A thick client
(interacting with a light server) provides powerful analysis. But
it is hard to maintain the service. A thin client (interacting with
heavy server) is limited with simple applications. However, it
can be used by many people (Garagon, 2002).
Figurel: Client-server model