Geoinformatics 2021 11-14 May 2021, Kyiv, Ukraine

GEOINFORMATICS 2021

21094

Development of a web portal for presenting earthquake observation data

*K. Brudko (Taras Shevchenko National University of Kyiv)

SUMMARY

This paper presents ways to create a modern, secure application for visualization of monitoring data on earthquake observations on the example of a geo-portal. The main criteria of the created website are UX- interface, cross-platform, fast and free access to geospatial information, selection of educational information about each seismic event.

The creation of the database-based model is the result of interaction of Python for Django technology and PostGIS. The MVT architectural template was used to design the website. Distinction between geospatial and textual information allowed to store new articles and publications directly in the database, with access to them from any platform. For the client part of the application, standardized technologies of HTML, CSS, JavaScript and their libraries are used. The built-in script for processing files GeoJSON API JavaScript for ArcGIS loads the map and displays geospatial data.

This web application does not require external resources, with the ability to add your own seismic maps, magnetometric data, etc.

According to this, it is possible to use a web portal to analyse the zoning of seismic hazards, provide information about catastrophic consequences, and create algorithms for their prevention and prediction.

Keywords: monitoring of hazardous phenomena, geospatial data, web portal, seismology.

Geoinformatics 2021

11-14 May 2021, Kyiv, Ukraine

GEOINFORMATICS 2021

Introduction Nowadays, visibility and availability of Internet technologies are the dominant factors that pay attention on majority of the community to choose of this source of information. The introduction of technology and the dissemination of knowledge through the visualization and structuring of data on hazardous phenomena is the most effective method of informing community. Prevention and prediction of catastrophic consequences is the main task of monitoring. That is why it is necessary to create a web application for visualization of seismic hazard monitoring data with a combination of modern technologies and their requirements, which provides fast, free and secure access to information. Implementing such task is not a trivial task. Solution of this problem is presented by a web portal for visualization of monitoring observations of earthquake data. It is extremely important to create cross-platform software, the format of which is accessible to most. The need of users to access a large amount of data that has geospatial information requires the use of intuitive representation of methods of presentation of geodata, as well as geospatial analysis. Therefore, a special API was used to process geospatial data - JavaScript API for ArcGIS (JavaScript API for ArcGIS Guide, 2021). This API is multi-platform and provides ability not only to visualize but also to process geospatial data in real time. Using the JavaScript API, you can create your own maps, develop web applications using a modern open data architecture using a modified JSON format, namely GeoJSON (H. Butler, M. Daly and others, 2016). Geoportals The vast majority of interactive maps are mapping services that allow users to view and display geographic data on map and perform simple manipulations with various geographic information systems (Bondarenko and Kyryliuk, 2020). Among the already created web portals, the USGS US Geological Survey is a good example. This web application provides information on hazardous natural phenomena in real time: deforestation, seismic activity, floods, villages, landslides and volcanic activity. The US Geological Survey also provides large scientific catalogues, publications and articles, multimedia materials, satellite images, a wide range of topographic, geological and physical online maps (official website of the US Geological Survey. Mapview). The USGS US Geological Survey uses its own GIS APIs to process metadata, search, and visualize geospatial data using its own interactive maps, which provide actual information about each object directly. Due to this, the web portal has a user-friendly and intuitive interface adapted for any user. A good example of web portal is the Hazards Monitoring Public Viewer site based on the Esri’s Disaster Response Program (DRP) platform. This map is intended to provide general awareness of earthquakes around the world. It is not intended to replace authoritative government websites but rather to provide situational awareness. This map contains Live Feeds from the Living Atlas including the Earthquakes layer which includes both recent event locations, PAGER Alerts and the Shakemaps. This map is provided by the Esri’s Disaster Response Program using the Public Information Solution template (Esri’s Disaster Response Program (DRP), 2021). The interface is concise, the data is interactive and structured, and therefore suitable for analysis. All this provides the user with comprehensive information that is necessary for both research and awareness of natural hazards. Technology solutions for the web portal The following technology stack was used to create web applications: Python for Django, HTML, CSS, JavaScript, PostgreSQL, JavaScript API for ArcGIS. PostgreSQL was used as a database. This database has several advantages: free access from any host, unlimited size, reliable transaction and replication mechanisms. It supports inheritance, versatility, and extensibility through libraries that store geospatial data such as PostGIS (PostgreSQL documentation, 2021). An important aspect is the support for Python for Django PostgreSQL management. PostgreSQL also works on all types of UNIX-like systems and MS Windows.

Geoinformatics 2021

11-14 May 2021, Kyiv, Ukraine

GEOINFORMATICS 2021

The Python for Django web framework was chosen for the server part of web portal development and administration. Django is a high-level open framework for developing web systems based on the Python programming language. Django provides modular development for creating mobile and therefore fast web applications based on ready-made solutions. Django's philosophy divides the developer's project by creating particles as different applications that can be reused in other projects. This greatly facilitates the work of the developer. Since Django was originally created as a tool for working with information resources, this has had a strong impact on its architecture: it provides a number of tools that help in the rapid development of informational websites. Therefore, providing publications to the user, as well as searching for articles is quick and easy (Django official documentation, 2021). The relevance of the UX-oriented interface improves the client's relationship with the web application, so the latest versions of the HTML5 and CSS3 standards have been used to create markup and styling. The selected tools are necessary for web application development and are used as a standard, according to the W3C World RFC standard. JavaScript, which is the best-known implementation of the ECMAScript standard, is the core technology of the DHTML method of developing web applications. Currently, one of the popular approaches to building web application user interfaces, based on DHTML is AJAX. This concept has made pages more dynamic and provides new features, namely dynamic loading and insertion of data into the document. The JavaScript API for ArcGIS was used to visualize geospatial data. ArcGIS web APIs allow web browsers to interact with ArcGIS for Server GIS services and draw (display) geographic data, as well as perform analysis. There are three types of web interfaces in ArcGIS: ArcGIS API for JavaScript, ArcGIS API for Flex, ArcGIS API for Microsoft Silverlight / WPF. The three APIs have the same functionality, but are designed to work with different development languages. To start developing web applications based on Flex or Silverlight, you need to download a special library. JavaScript web APIs do not require a library to be loaded, as this library is accessible via a URL (JavaScript API for ArcGIS Guide, 2021). This makes service completely cross-platform. This technology allowed to create widgets for visualization of compact geospatial information and data analysis in a user-friendly format. This meets standards of dynamism and mobility in the development of the latest web applications. Project implementation practice The result of the work is the creation of a web portal for visualization of monitoring data on earthquake observations. The database model (Figure 1) illustrates idea of structured and personalized storage of geospatial information. Data are normalized, updated and correct. The created model is mobile and allows storing an unlimited amount of spatial information together with textual information of news and articles. Built-in extensions of the selected database facilitate and speed up the implementation of interaction between the application and the user, thereby increasing the likelihood that user will continue to work with the portal.

Figure 1 Example of a model in a database. The part of the model responsible for storing geospatial and information data is shown

Geoinformatics 2021

11-14 May 2021, Kyiv, Ukraine

GEOINFORMATICS 2021

Geospatial information was stored in the portal database using the software product PosrgreSQL. The USGS US Geological Survey server resource was selected as the source of earthquake monitoring data. The data is provided in the usual GeoJSON format for exchange between the user and the server, with the possibility of updating it at the user's request. The interaction between the USGS US Geological Survey service and the portal database was implemented in the Python programming language, namely the psycopg2 library (psycopg2 - Python-PostgreSQL Database Adapter, 2020). Python for Django was used to develop the server part of the program. The creation of the database-based model is the result of interaction of Python for Django technology and PostGIS - spatial database extender for PostgreSQL. The distinction between geospatial and textual learning information is the idea of creating several separate models that interact with each other based on the relationship to each other. This allowed new articles and publications to be stored directly in the database. In this way, user can access them from any platform, if necessary even on a local host. The administrative part of Python for Django allows authorized user from portal to publish news and update information about seismic hazards. All articles are divided into categories and carry information about specific earthquakes, which provides an opportunity to simultaneously obtain relevant information and conduct geospatial analysis of monitoring data. Python for Django technology has greatly facilitated the web portal development process due to its adaptability to work with information data and mobile capabilities. To create a UX-accessible portal interface, that the client part of the program (Figure 2), it was necessary to use technologies HTML, CSS, JavaScript and their libraries. JavaScript libraries were used to structure the data. The web portal project templates use virtual links in the CSS style of the open Bootstrap tutorial (Bootstrap documentation 4, 2021).

Figure 2 Example of visualization of earthquake monitoring observations on the web portal. Pop-up window with earthquake characteristics The built-in ArcGIS API scenarios were used to achieve the main goal of the project, namely visualization and research of monitoring geospatial data. The web portal is created without the need to create a web server, providing ability to use virtual ArcGIS servers through links to them. Information is provided to user according to this algorithm. By selecting the appropriate page of the portal, the user notifies about his desire to explore the interactive map. Then data sent to the server, or rather the database query. Server generates GeoJSON data, which are sent after to the client side of the website. The JavaScript API for ArcGIS loads map and displays the resulting GeoJSON file using a built-in script to process files of this type. As a result, data is visualized on web portal (Tarnovetskyi and Demidov, 2020). Now user can turn to the interactive map and get information not only about the spatial location, but also the properties of each object, and therefore use portal to analyse the zoning of seismic hazards. By clicking on the link in the pop-up window, user can get acquainted with educational information, the latest news, publications on the earthquake. This information in the form of an article

Geoinformatics 2021

11-14 May 2021, Kyiv, Ukraine

GEOINFORMATICS 2021

is downloaded directly from the database of the portal. This technology is quite intuitive, carries clearly structured information, and therefore will be easily perceived by both the scientific community and the average citizen. Conclusions Creating a modern web portal for working with geospatial data requires a lot of effort and attention. Selected technologies: Python on Django for the server part; HTML, CSS, JavaScript, Bootstrap 4 for the client side; PostgreSQL for data storage and JavaScript API for ArcGIS for visualization of geospatial information provide relevance and allow to optimize work of the web portal, allowing it to stay up-to-date. External resources are not required for this web application, as it provides ability to analyse and study the already created package of information. At the same time, providing data updates as needed by user. A set of publications and articles makes the portal an important source of information, a free stack of technologies ensures its multiplatform. As additional data of a different nature for analysis on the portal can be added, for example, geological or geophysical data by layers (e.g. geological orientation data (Menshov et al., 2018; 2012). According to this, it is possible to use a web portal to analyse the zoning of seismic hazards, provide information about catastrophic consequences, and create algorithms to prevent them. Developing geospatial web applications in today's environment is not a temporary process. In the future, it is planned to use the web portal to create algorithms for the analysis of seismic zones, to predict the risks associated with them with further visualization directly on the web portal. Website will adapt and develop, introducing new algorithms for disseminating information. All technologies used on the web portal are licensed under open license, which provides free access of all potential stakeholders to such decisions. References Bondarenko, E. and Kyryliuk, M. [2020] Interactive map of the nature reserve fund of Ukraine in the

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