The 2020 M 5.9 Falam Earthquake the Subduction-Induced Strike-Slip Earthquake, West Myanmar

Abstract

An earthquake with magnitude 5.9 occurred in the east of Falam on 16th April, 2020 at 11:45:23 (UTC). The epicenter is situated at latitude 22.789°N, longitude 94.025°E, 38 km ESE of Falam, at the depth of 10 km. Focal mechanism solution for this event is normal faulting (USGS). The epicentral location is in the Kabaw Valley along which Kabaw fault runs through in N-S direction. The Kabaw fault is situated in forearc region at the eastern base of N-S trending Rakhine Western Ranges under which the India oceanic plate is obliquely subducting beneath the Burma continental plate. The 2020 M 5.9 Falam earthquake occurred along two closely linked tectonic settings: north-eastward oblique subduction zone and north-south trending Kabaw fault zone system in the forearc region.The Falam earthquake ruptured the Tripura segment, one of the segments of India subduction zone, located approximately between latitude 22°-24°N according to the geographical location. This event is a rare intraplate earthquake and a subduction-induced strike-slip earthquake that ever occurred for the recent time in Myanmar. The shock was felt by cities of Gangaw, Kalemyo, Kalewa, Mandalay, Kyauk-se, Monywa. This earthquake was preceded by a loud sound and shaking lasts 1 minute. A few aftershocks of magnitude >3.5 followed the main shock in the vicinity of the epicenter. The vibration spread a wide area along Rakhine Yoma and Myanmar lowland area. The investigation of field survey from social media was found that the event reaches Modified Mercalli Intensity scale VIII based on people’s perception, indoor effects and damaged buildings. Damage is severe in some poorly built structures and upper parts of stupa and pagodas.