Reconstruction of paleoearthquakes impact and its return period perspective study to support infrastructure resilience program (case study: paleoearthquakes in mainland island of Sumatra)

Abstract Sumatra island is one of earthquake prone area in Indonesia. Some of paleoearthquakes occurred in Sumatra Island and its vicinity as like earthquakes in Siberut island on 1797 with magnitude (M) 8.6-8.8, Bengkulu on 1833 (M 8.8-9.1) and Nias island on 1861 (M ∼8.5). All of earthquakes triggered of tsunami. Beside that some of paleoearthquakes occurred also in mainland island of Sumatra like as the earthquake on 1822, 1892 (M ∼ 7.7), 1909 (M∼7.6), 1921 (M∼7), 1933 (M∼7.5) and 1936 (M∼7.1) respectively. The purposes of this study to reconstruct of paleoearthquakes shaking impact, and estimation of earthquake return period (Tr) to support a long-term infrastructure resilience program. The result consist of the maximum intensity (on MMI scale), Peak Ground Acceleration (PGA)(% g) and Peak Ground Velocity (PGV)(cm/s) of earthquakes 1822, 1892, 1909, 1921, 1933 and 1936. There are maximum intensity about VI-VIII MMI, PGA about 25-56 % g and PGV about 15 - 48 cm/s respectively. Whereas calculate of earthquake return period estimation (Tr) is used scaling law relations of earthquake and the slip rate values ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mi>v</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> ). After calculating we found the Tr of earthquake 1892 (MCE 7.7 and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mi>v</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> 6.5 mm/y), earthquake 1909 (MCE 7.2 and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mi>v</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> 14 mm/y) and for earthquake 1921 (MCE 7.0 and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mi>v</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> 8 mm/y) is about of Tr ≤ 563 y, Tr ≤ 228 y and Tr ≤ 174 y respectively.