# Preliminary Seismic Hazard Analyses for the Ugandan Region
## 2 Literature Review  
Previous work on the seismicity and seismic hazard of Uganda have been conducted mboxciteB4-applsci-1537376,B6-applsci-1537376. There has so far been only one seismic hazard analyses conducted for Uganda as a whole [4]. The study compiled earthquakes in and around Uganda from 1900 to 1991 and homogenized them to surface wave magnitude, \(M_{\rm S}\), for their earthquake catalog. Based on that catalog, the researcher separated the study area into 13 seismic zones for analyses. However, the study employed only one ground motion prediction equation (GMPE) calibrated for eastern Canada and assumed a range of standard deviations that may or may not have been recommended by the original eastern Canadian GMPE [13]. To compound matters, there appear to be several misprints in the publication. The study noted a PGA between 0.5 and 0.6 m/s\({}^{2}\), or 0.05 to 0.06 g, to be experienced in the whole country, except the areas close to the rifts. For areas in or close to rift areas, the study found that the expected PGA would be between 1.0 and 2.2 m/s\({}^{2}\), 0.1 to 0.2 g, on average once every 50 years. The study then concluded by calculating the frequency of occurrence of a 2.0 m/s\({}^{2}\), or 0.22 g, PGA level of shaking in several parts of Uganda. In the northeast, such a damaging earthquake would occur once in more than 3000 years. For the southern areas, excluding in or close to the rift valley, such a destructive earthquake would occur once every 1000 to 1500 years on average, and for the zones in or close to the rift valley, once every 50 years on average.  
Another study evaluated the possible seismic hazard from earthquakes in the Albertine graben with specific interest in the districts of Hoima and Bulisa in Uganda [6]. They used an earthquake catalogue of moment magnitudes compiled from 1900 to 2012 from the surrounding areas. They divided the Albertine region into two seismic source zones and used one GMPE [14], suggesting the other two GMPEs under consideration were unreliable, one of them being from the seismic hazard study for Uganda [4]. They showed hazard maps for PGA at 2%, 5%, and 10% probability of exceedance in 50 years. They also estimated PGAs of 0.152 to 0.162 g, 0.187 to 0.195 g, and 0.248 to 0.256 g for return periods of 475, 975, and 2475 years, respectively. They noted the southwestern corner of the Hoima district had the highest levels of seismic hazard, with PGAs above 0.162, 0.195, and 0.256 g for 10%, 5%, and 2% probabilities of exceedance in 50 years, respectively.  
In addition to seismic hazard analyses, a few works on GMPEs related or relevant to Uganda have been conducted. One study focused on the attenuation relations for Eastern and Southern African regions; however, characterizations of strong ground motions in those areas were virtually nonexistent due to a lack of data [15]. That study attempted to establish average attenuation relations based on unplanned vibration theory by means of some of the latest earthquakes which were documented by digital stations in those areas. The work noted applicability in stable continental regions and shallow crustal regions. Another study developed a GMPE for strong ground motions in a section of the Kivu area located in the western segment of the East African Rift System and surrounding areas including Uganda [16]. The relationships proposed were based on simulations of strong motions of big earthquakes using recordings from minor earthquakes. The resultant GMP was a series of equations separated by magnitude.