Rapid Assessment of Source Characteristics and Impacts of the 21 November 2025 MW 5.44 Narsingdi Earthquake, Bangladesh,

The M w 5.44 Narsingdi Earthquake of 21 November 2025 occurred near Dhaka, the Capital City of Bangladesh, which is characterized by high population density and unplanned, unorganized development, with many old, non-engineered buildings. Although the earthquake was moderate in magnitude, poor construction practices caused significant shaking in the buildings in Narsingdi and Dhaka. The modeled peak ground acceleration (PGA) of this study ranges from 0.165 to 0.175 g in Narsingdi and approximately 0.10 g in Dhaka. This study also prepared an intensity map based on the Modified Mercalli Intensity (MMI) Scale, using shaking intensity felt by the population and infrastructure in Bangladesh. The maximum intensity (MMI Scale) of this earthquake was VI in and around the mainshock area of Narsingdi and V in Dhaka, Gazipur, and Narayanganj, decreasing radially with increasing distance from the epicenter. Structural damage was observed primarily in Narsingdi, where cracks developed in numerous buildings and several structures were reported to have tilted. This rapid assessment is consistent with a possible fault beneath Narsingdi at a depth of approximately 25.5 km. Fault modelling based on the focal mechanism indicates that aftershocks following the 21 November 2025 event are related to the mainshock fault, with maximum shaking concentrated in the same areas, further supporting these findings. The seismic source identified in this study is further corroborated by a M 4.4 earthquake that occurred on 22 June 2026, near the epicenter of the 21 November 2025 Narsingdi earthquake. Given the occurrence of small to moderate earthquakes in this region, immediate identification of fault sources in Bangladesh, particularly beneath Dhaka, is essential due to the high population density and predominantly unplanned infrastructure.