Website design of a spatial data dissemination system and soil classification based on geotechnical engineering (case study: Surabaya City)

. The Indonesian Meteorology, Climatology, and Geophysics Agency (BMKG) provides information on meteorology, climatology, and geophysics related to soil classification and characteristics. This data is crucial for spatial mapping and needs to be easily understood by the public. Soil classification mapping is vital for urban planning and earthquake mitigation in densely populated areas. To address this, a website was created for easy access to soil classification mapping data in Surabaya. The website utilizes QGIS for raster map processing. Users select parameters to display interactive raster maps with measured values for assessing soil conditions. A survey evaluated the website and app, resulting in 77,2% to 85,7% user satisfaction. The study confirms their usability and effectiveness. This journal presents the system's design and implementation for disseminating spatial data and soil classification information. It highlights the potential for supporting efficient urban planning and earthquake risk mitigation, benefiting the public and authorities.


Introduction
BMKG (the Indonesian Meteorology, Climatology, and Geophysics Agency) is responsible for providing valuable information on Meteorology, Climatology, and Geophysics (MKG), including geophysical data relevant to soil classification and characteristics.The dissemination of soil classification information is crucial for spatial data mapping and is designed to be easily comprehensible for the general public.
Surabaya City, the second-largest city in Indonesia, has a population of approximately 2.87 million people.It covers an area of 326.81 square kilometers and has a population density of 8,795 people per square kilometer according to the 2020 Population Census.Due to its tectonic conditions, Surabaya City is situated along the active and moving Kendang Fault, which demands special attention.Recent studies have shown that the Kendang Fault is actively moving, making it a seismic source in the East Java region.
Mapping spatial data for soil classification is essential in densely populated areas to support efficient urban spatial planning and disaster mitigation, especially for sudden earthquakes.
Based on these considerations, the development of a spatial data dissemination system is needed to facilitate access to soil classification and characteristic information for both the public and relevant authorities.In line with this, the authors aim to design a user-friendly website to provide easy access to soil classification mapping data in Surabaya City.This research is expected to contribute significantly to seismic hazard mapping and earthquake disaster mitigation, as well as support urban spatial planning in Surabaya City for efficient and well-measured development activities.

Seismic method
Seismic method is one of the geophysical methods used in the study of rock geophysics based on the characteristics of seismic waves.Seismic waves are generated by a seismic source, which produces waves that propagate through the ground or rock in all directions and are reflected when they encounter rocks with different contrast velocities.These reflected waves are then captured by receivers at specific distances from the source on the surface as a function of time.The data received by the receiver provides information about subsurface layer structures [1].

Multichannel Analysis of Surface Waves (MASW)
The Multichannel Analysis of Surface Waves (MASW) method is a seismic technique that utilizes the dispersive nature of surface waves to interpret the surface wave velocity directly related to the subsurface hardness to a depth of up to 30 meters.This method is useful in geotechnical engineering to interpret the shear wave velocity beneath the surface of a particular area, explaining the subsurface stiffness by forming the shear wave velocity relative to depth [2].

Horizontal to Vertical Spectral Ratio (HVSR)
The Horizontal to Vertical Spectral Ratio (HVSR) method involves calculating the microtremor data by determining the ratio of horizontal (H) to vertical (V) components that appear in the floor vibration spectrum based on the collected data.Microtremor data from one station describes the ground vibration velocity in three directions: north-south (N-S), west-east (E-W), and vertical (U-D), represented in the time domain [3].

Probabilistic Seismic Hazard Analysis (PSHA)
Probabilistic Seismic Hazard Analysis (PSHA) is a method of analyzing seismic hazard that incorporates uncertainties related to earthquake magnitudes, locations, and frequencies to obtain Peak Ground Acceleration (PGA) values.In seismic hazard analysis conducted using the probabilistic method, the maximum ground acceleration values are determined for return periods of 200 years, 500 years, 2500 years, 5000 years, and 10,000 years [4].

Velocity of Shear Waves in the Upper 30 Meters (Vs30)
Vs30 refers to the shear wave velocity occurring from the surface to a depth of 30 meters.Information about Vs30 is used to classify rock types based on the intensity of seismic vibrations caused by local factors.This data is also utilized in the process of designing earthquakeresistant buildings.The shear wave velocity in the upper layers of the soil, such as the ground surface or layers close to the surface, can influence the behavior of vibrations during an earthquake.Vs30 is used as an estimate to determine the level of ground motion amplification in the respective area [5].

Seismic Vulnerability Index (Kg)
The Seismic Vulnerability Index (Kg) is an index used to evaluate the vulnerability of surface soil layers to deformation during an earthquake.Factors that influence seismic vulnerability include low strength of sediments, whereas stronger and more stable rock formations generally do not cause amplification.The value of the seismic vulnerability index provides information about the potential magnitude of ground shaking caused by an earthquake in that area [6].

Amplification (A0)
Amplification occurs when seismic waves are magnified due to significant differences between the layers they pass through.This is controlled by the difference in impedance between soft layers and bedrock.Waves will be amplified when propagating from a harder to a softer medium.Amplification can also be influenced by rock deformations, such as weathering, folding, or faulting [6].

Dominant frequency (f0)
Dominant frequency refers to the frequency value that often appears and is recognized as a representation of the frequency of rock layers in a particular area.Therefore, the dominant frequency can provide indications about the type and characteristics of rocks present in that region.In this context, the dominant frequency value can be used as a clue to identify rock types and understand their characteristics [7].

Dominant period (Tdom)
Dominant period is the time taken by microtremor waves to travel through surface sedimentary layers or experience one reflection on a surface reflection plane.It indicates the characteristics of rock layers in an area, providing information about the type and properties of the rocks present [7].

Peak Ground Acceleration (PGA)
Peak Ground Acceleration (PGA) is the measure of the maximum acceleration that occurs on the ground during an earthquake.The calculation of PGA can be based on earthquake magnitude and depth using empirical methods.This ground acceleration is caused by the earthquake and indicates the inertia forces that will affect building structures [8].

Geographic Information System (GIS)
Geographic Information System (GIS) is computerized information stored in a database and used to process geospatial georeferenced data (details, facts, conditions, etc.) related to issues and situations in the real world system.The advantages of Geographic Information Systems are that they generally provide almost realistic information, predict outcomes, and enable strategic planning based on the integration of five components: data, software, hardware, users, and applications [9].

Quantum GIS (QGIS)
Quantum GIS is one of the open-source software under the official project of the Open-Source Geospatial Foundation (OSGeo), which can be run on Windows, Mac OSX, Linux, and Unix operating systems.This application enables the processing of spatial data in various formats, as well as vector, raster, and database functions.Quantum GIS software can be used as an alternative to commercial GIS software such as ArcView, MapInfo, and ArcGIS [10].

HTML
HTML stands for Hypertext Markup Language, and it is the markup language of the World Wide Web.This language determines the format of WWW documents and enables the addition of hypertext links to the documents.In development, there is an addition to HTML known as Dynamic HTML (DHTML).Thanks to this advanced language, HTML can not only display static information but also dynamic content [11].

CSS (Cascading Style Sheets
) is a style sheet language used to control the appearance of a website, including layout, fonts, colors, and all visual elements.In general, CSS is used to format web pages that are written in HTML or XHTML.With CSS, users can control and modify the visual appearance of web pages separately from their content structure, enabling a clear separation between visual presentation and content on the website [11].

Javascript
JavaScript is a scripting language used to make web documents more interactive.In other words, it is a programming language that provides additional functionality to HTML (HyperText Markup Language) by allowing commands to be executed on the client side of web documents, not on the server side [12].

Leafletjs
Leaflet JS is an open-source JavaScript library used to build interactive web-based map applications.It supports both mobile and desktop platforms and utilizes HTML5 and CSS3.Leaflet is also compatible with OpenLayers and Google Maps API, which are popular JavaScript libraries for building map applications [13].

Related work
Figures Similar research aiming to develop an informative GIS-based website has been previously conducted by Harjono (2017) on the Geographic Information System for Lightning Distribution and Vulnerability at the Geophysical Station Class I in Tangerang.The study utilized Google Maps to display the geographical coordinates of lightning strikes, accessible through the website [14].
In his research, Harjono (2017) obtained several coordinate points of lightning distribution with a userfriendly interface using Google Maps [14].Kusuma (2015) conducted a study resulting in a Tourism Information System for Sidoarjo Regency using WebGIS technology, displaying tourism information in the form of satellite and terrain maps.The system was equipped with features for completing information, adding locations, searching for tourist objects, and providing website interface assessments [15].
Based on usability testing through a questionnaire consisting of five components, namely learnability, efficiency, memorability, errors, and satisfaction, Kusuma (2015) found that 70.69% of respondents provided a positive evaluation for the website.Therefore, it can be concluded that the website is considered suitable and meets usability criteria [15].

System design 4.1 Block diagram
A block diagram is a representation of the relationships between the functions of components in a system.The block diagram consists of inputs, processes, and outputs.The following is a block diagram of the system to be created.

Website system flowchart
Flowchart is a method of analytical technique used to describe number of aspects on the information system in a clear, concise and logical manner.The website system flowchart in this study can be seen in Figure 2.

Display of Base Map
On the Base Map page, there is an administrative map of Surabaya city divided into each sub-district (Kelurahan).The display of Basemap can be seen in Figure 5.

Display of map sub-menu
On the map sub-menu page, there are several submenus, including Vs 30 (MASW), Vs 30 (HVSR), Kg, A 0 , f 0 , Tdom, and PGA.After selecting one of the menus, users can view an interactive map of the chosen seismic method.The display of map sub-menu page can be seen in Figure 6.

Display of Information
On the Information menu, there is information about the definitions or explanations of seismic methods along with their supporting parameters.The display of Information page can be seen in Figure 7.

Survey result
After conducting website testing using the survey method, the results showed a percentage ranging from 77,2% to 85,7% as shown in Table 3.Based on these results, it can be concluded that the built website is categorized as suitable or meet the usability criteria.