DEVELOPING A WEB-BASED GIS APPLICATION 
FOR EARTHQUAKE INFORMATION 
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 
ABSTRACT: 
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. INTRODUCTION 
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). 
SERVER 
COMPUTER 
CLIENT 
COMPUTER Request 
INTERNET 
Response 
HTTP SERVER SOFTWARE 
WWW BROVW SER 
Figurel: Client-server model