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A Lesson Learnt from the 2025 M7.7 Mandalay, Myanmar, Earthquake and its Application to Seismic Hazard Assessment

Description: 

We accessed shake maps from the 2025 M7.7 Mandalay, Myanmar, earthquake, evaluated seismic model for the Sagaing fault, and revised our probabilistic seismic hazard assessment (PSHA) based on insights gained from this event. We conducted a deterministic seismic hazard assessment (DSHA), incorporating the earthquake’s rupture parameters and site conditions characterized by V S30 (the average shear wave velocity in the uppermost 30 meters of the ground surface), to generate updated shake maps. Our results indicate that regions intersected by the rupture along the Sagaing Fault likely experienced intense ground shaking with Modified Mercalli Intensity (MMI) values exceeding VIII. Severe shaking was also identified in western Mandalay and southern Sagaing—both densely populated areas with critical infrastructure, including downtown Sagaing, the Sagaing Bridge (which collapsed during the earthquake), and downtown Mandalay.

To further evaluate potential seismic hazards along the Sagaing Fault, we constructed a magnitude-frequency distribution of regional seismicity. The results show that seismic activity for M < 6.0 follows the Gutenberg-Richter (G-R) law, while larger events deviate from it, possibly due to catalog incompleteness. This 2025 earthquake ruptured across multiple fault segments, deviating from the traditional PSHA assumption that large earthquakes occur on single, isolated seismogenic structures. To better account for such complex rupture behavior, we used the Seismic Hazard and Earthquake Rate In Fault Systems (SHERIFS) model to estimate seismic rates along the Sagaing Fault’s multiple segments. Using this approach, we assessed seismic hazards across Myanmar, with a focus on key metropolitan areas including Mandalay, Sagaing, Taungoo, Bago, and Yangon. Comparison of the updated shake maps with Myanmar’s 2016 building code indicates that most regions did not experience shaking levels that exceeded the design standards, reinforcing the importance of adopting and implementing modern building codes for seismic resilience.

Session: Late-breaking on Recent and Future Large Earthquakes [Poster]

Type: Poster

Date: 4/15/2025

Presentation Time: 08:00 AM (local time)

Presenting Author: Chung-Han

Student Presenter: No

Invited Presentation: 

Poster Number: 149

Authors