Does Singapore have active faults? Emerging geomorphic, sedimentological, and coral microatoll evidence for recent coseismic rupture

Aron J. Meltzner, Liam L. Newman, Fangyi Tan, Tingli Yan, Lin Thu Aung, & Yu Wang

Submitted August 30, 2026, SCEC Contribution #15540, 2026 SCEC Annual Meeting Poster #106

Singapore is commonly believed to be tectonically stable, with seismic hazard thought to arise solely from distant Sumatran earthquakes. This view, however, overlooks two M≥5 earthquakes in 1922, less than ~140 km away in neighboring Johor, and a 1948 event reported only from southern–central Singapore that produced EMS intensities IV–V at multiple closely spaced sites, consistent with a local source and M≈4. Although mapping has identified numerous bedrock faults across Singapore, their activity and seismic potential remain largely unexamined.

The Downtown Core is underlain by the low-lying Kallang Basin and adjacent reclaimed land, where Late Quaternary sediments exceed 40 m in thickness. Immediately to the west, Cretaceous to Pliocene bedrock rises to ~50 m above sea level. We interpret the steep, east-dipping bedrock–sediment contact as a potentially active, oblique-slip fault, which we name the Fort Canning fault; it may form part of a transtensional stepover within a longer, northwest-trending dextral fault system. Legacy borehole data reveal abrupt vertical steps in the thalwegs of at least three east-flowing buried paleochannels, increasing from 6 m in the north to 20 m in the south, where the channels cross the inferred fault. Each paleochannel may also show southward deflection, although resolution is limited by borehole spacing.

Lazarus, a 1-km-long island km south of mainland Singapore, is a plunging syncline apparently bisected by an unmapped, northwest-striking fault. The inferred fault runs along the syncline axis and bisects a field of fossil coral microatolls that grew 7000–7800 cal yr BP. In-situ microatolls show systematic elevation differences across the fault, with those to the northeast ~30 cm higher than coeval counterparts to the southwest, consistent with post-growth vertical displacement. Many microatolls at the site are tilted about their centers, with a strong preferred northeastward tilt direction, suggestive of strong ground motion. Together, the elevation difference and widespread northeastward tilting are consistent with coseismic uplift of northeastern Lazarus Island during a significant earthquake sometime after the youngest corals died ~7000 years ago.

Whether the Lazarus Island and Fort Canning faults are connected is uncertain, but their geomorphic, sedimentological, and coral-based evidence challenges the assumption that Singapore is tectonically quiescent and motivates renewed evaluation of local seismic hazard.

Key Words
Singapore, boreholes, coral, microatolls, transtensional, stepover

Citation
Meltzner, A. J., Newman, L. L., Tan, F., Yan, T., Aung, L., & Wang, Y. (2026, 08). Does Singapore have active faults? Emerging geomorphic, sedimentological, and coral microatoll evidence for recent coseismic rupture. Poster Presentation at 2026 SCEC Annual Meeting.

Related Projects & Working Groups
Earthquake Geology