Do Your Seismic Parameters Accurately Reflect Site Conditions?

In the planning and design of facilities and infrastructure, seismic parameters are essential inputs for determining structural and foundation design requirements. However, regional seismic parameters do not necessarily represent the actual seismic response of the soil at a project site.

Each site has its own geological conditions, soil layer profiles, dynamic characteristics, and response to seismic waves. Therefore, projects with specific importance levels or site conditions requiring more in-depth evaluation may need a Site-Specific Seismic Analysis (SSRA).

Why Should Site Conditions Be Considered?

Seismic waves can undergo changes in their characteristics as they propagate through soil layers toward the ground surface. This response is influenced by:

• Soil layer profiles and thicknesses

• Shear wave velocity

• Soil dynamic characteristics

• Geological conditions

• Earthquake sources and characteristics

Consequently, sites with different soil conditions may exhibit different surface responses, even when located within the same seismic region.

What Is Site-Specific Seismic Analysis (SSRA)?

Site-Specific Seismic Analysis (SSRA) is an approach used to evaluate seismic response by considering the specific characteristics of a particular location.

The process can be illustrated as follows:

Seismic Hazard → Site Characteristics → Ground Response → Design Parameters

This analysis connects seismic hazard assessment with soil conditions to understand how seismic waves propagate through soil layers to the surface and generate parameters relevant to design requirements.

Thus, the analysis considers not only the potential magnitude of an earthquake but also how the soil at the project site responds to seismic activity.

From Seismic Hazard to Design Parameters

One of the key parameters in seismic evaluation is Peak Ground Acceleration (PGA), which represents the maximum ground acceleration under specified earthquake loading conditions.

However, PGA values must be understood within the context of the analysis, including:

• Seismic hazard and earthquake sources

• Geological conditions and soil profiles

• Shear wave velocity

• Soil dynamic characteristics

• Wave response within soil layers

• The period and hazard level being evaluated

Therefore, the engineering question is not simply, “What is the PGA value?” but also, “What site conditions and hazard levels does this PGA represent?”

How Is Site-Specific Seismic Analysis Conducted?

Site-specific analysis integrates seismic data and site conditions through several stages.

1. Seismic Hazard Assessment

Identifying earthquake sources and the hazard levels relevant to the project location.

2. Site Condition Assessment

Understanding soil layer profiles, geological conditions, and relevant dynamic parameters.

3. Ground Response Analysis

Evaluating the response of seismic waves as they propagate through soil layers toward the ground surface.

4. Design Parameter Determination

Generating seismic parameters relevant to the site conditions and design requirements.

5. Engineering Recommendations

Translating the analysis results into technical recommendations to support project engineering requirements.

Through this process, SSRA connects seismic hazard, soil characteristics, site response, and design requirements within a comprehensive evaluation framework.

Case Study: TBBM Maumere Development Project

Promisco has experience providing Site-Specific Seismic Analysis (SSRA) and PGA Assessment Services for the TBBM Maumere Development Project.

In this project, site-specific analysis was used to help determine seismic parameters appropriate to the site conditions as part of the project’s engineering requirements.

Relevant capabilities for this project include Geotechnical Investigation, Soil Investigation, Seismic Hazard Analysis, Site-Specific Seismic Analysis (SSRA), PGA Analysis, soil dynamic characteristic evaluation, Ground Response Analysis, and Engineering Recommendations.

A data-driven approach supported by engineering judgment helps integrate soil conditions and seismic characteristics in accordance with project requirements.

Promisco’s Engineering Capabilities

Beyond seismic analysis, Promisco also provides engineering capabilities to support soil condition assessments and the development of technical solutions tailored to project requirements.

Slope Stability Analysis

Evaluating slope stability conditions to understand potential movement and soil behavior.

Reinforcement & Drainage Design

Developing reinforcement and drainage system designs that consider technical requirements and actual field conditions.

Adaptive Construction Recommendations

Recommending construction methods that account for site access, safety, and actual field conditions.

These capabilities support a geotechnical engineering approach that considers soil characteristics, technical risks, and project execution requirements.

Why Is Site-Specific Analysis Important for Your Project?

Appropriate seismic parameters require an understanding of both earthquake hazards and site characteristics. Through seismic hazard assessment, soil dynamic characterization, and ground response analysis, design parameter requirements can be evaluated more specifically in accordance with site conditions and project requirements.

Need seismic analysis and geotechnical solutions tailored to your site conditions?

Consult with PT Promisco Sinergi Indonesia about your project requirements through Promisco’s Geotechnical Engineering services.