How can you estimate peak ground acceleration for a site?

It is very important to understand the probability of exceedance adopted in the read map and the proper mechanism for compensating it in the FEA, the analysis mechanism, and the standards followed.

This is the most easy way to get the peak ground acceleration to be used on a project. To use seismic hazard maps, you just need to locate your site on the map and get the corresponding PGA for desired return period, damping and other parameters. Other global hazard maps are USGS, KiK-net/K-net. However, not all sites are available.

its prefer to use hazard maps instead of empirical equations. I believe by experience that it is not accurate specifically in S1 as it gives exaggerated results.

To estimate peak ground acceleration for a site, I will prefer a seismic hazard analysis, considering the site's location, geological conditions, and seismic history. Utilizing seismic hazard maps and probabilistic seismic hazard assessments, we can calculate the expected ground motions, taking into account factors like soil type, fault proximity, and local geological features. Additionally, site-specific investigations, such as geotechnical surveys, would provide valuable data for a more accurate estimation. Combining all these factors allows for a comprehensive assessment of peak ground acceleration and ensures the structural design meets the necessary seismic resilience standards.

Using ground motion prediction is critical because we need to check the parameters used in the equation (study) and we need to check if this is applicable in our project. There are a lot of ground motion predictions equations available such as the Joyner-Boore equations but engineers need to be careful using empirical equations.

In my opinion, this is the most used method to get the ground motion of a specific location where seismic hazard maps are not available. To get the PGA from the site response analysis, you need to get the soil parameters from the geotechnical investigation and determine the response spectrum of the site either using (code-based either ubc-97 or ASCE) or PSHA then determine the historical available ground motion with the same soil parameters in the USGS database and scaled it to your site response spectrum then you get the appropriate ground motion and determine the PGA.

Earthquake is a combination of both linear and circular motions in all three axis i.e. X, Y and Z-axis. If we can install a sensor such as "Inertial Measurement Unit (IMU)" to measure these accelerations in all these axis and then apply some filters (low-pass and high pass) to merge both these linear and circular motions to get a value of acceleration in all three dimensions. Then during an earthquake, it will record all the values both on primary and secondary waves and after earthquake we can see its PGA by looking at the complete data of every second and mark its intensity and scale based upon that PGA value. We can also increase the number of devices to increase accuracy of PGA.

Seismic hazard maps for a region are a good start. However best to undertake a historical seismic historical analysis for the region. The greater number of years going back the better. However newspaper reports of damage that occurred could only probably go back for less than 200 years. For activity that occurred 500 years ago archive searches are undertaken. Being aware of the damage that occurred to the buildings together with its building material & the founding material built upon, can help in identifying the intensity of the seismic strike & hence relating it to a scale on the MSK index. There is correlation between the MSK intensity grade & PGA. Next identify the probability of occurrence to obtain the 475-year period of occurrence.