DOI: 10.5281/zenodo.17234830
title: Tsunami Models from Negros–Sulu Megathrust (Philippines) Rupture Scenarios

description: This is a supporting dataset for the manuscript "Seismic and Tsunami Hazard Potential of the Negros–Sulu Megathrust, Philippines."

The tsunami models are based on 18 shallow blind megathrust rupture scenarios from six segments (NT1-1, NT1-2, NT2, ST, ST1, ST2) and three dip angles (10d, 20d, 30d). The tsunami simulation is run through the JAGURS code (Baba et al., 2015, 2017), analytically solved through Green’s function, assuming a homogeneous isotropic elastic half-space (Okada, 1985) and utilizing the average slip from the scaling equation of Allen and Hayes (2017). The tsunami wave propagation is modeled using two-dimensional nonlinear shallow water equations through the finite difference method (FDM) in a staggered grid, accounting for the initial vertical and horizontal seafloor displacement and Boussinesq dispersion effects. The 4-h simulation assumes a uniform surface roughness (Manning’s coefficient = 0.025 s m-1/3).

The raster datasets are the maximum wave velocity (m/s) and maximum wave height (m) from 18 rupture scenarios. with the inclusion of the average and maximum values from all scenarios. 

The vector files contain the maximum flow velocity (m/s), maximum wave height (m), and minimum arrival time (min) in 6,879 coastal points surrounding the Sulu Sea, based on 18 megathrust rupture scenarios.

The TGS files contain the 34 synthetic tide gauge stations with the x-axis (fx) and y-axis (fy) velocity (m/s) and vertical (hz) displacements (m) within the 4-h simulation at 0.5 s (t) intervals from 18 source parameters.

 

 

This study forms part of LN’s Master’s thesis, “From Trench to Coast: Investigating the Late Quaternary Tectonic History and Seismic Hazard Potential of the Negros–Sulu Trench System, Philippines”, conducted at the University of the Philippines Diliman.

Nawanao, L, Ramos, N., Baba, T., Chikasada, N., and Satake, K. Seismic and Tsunami Hazard Potential of the Negros–Sulu Megathrust, Philippines

Abstract:

The Negros–Sulu megathrust poses an imminent threat to coastal communities surrounding the Sulu Sea, but with limited information on past tsunamis, megathrust geometry, and locked segments, robust seismic and tsunami hazard assessments are hindered. To identify highly exposed coastal areas amid this knowledge gap, we estimated the Negros–Sulu megathrust source parameters using a structural-based segmentation and scaling-relation approach for tsunami modeling. A total of 18 sets of source parameters from six segments and three dip angle scenarios were considered with moment magnitude and average slip of Mw 8.0–8.9 and 1.68–6.23 m, respectively. Tsunami simulations were modeled in JAGURS, accounting for nonlinear shallow water equations, horizontal and vertical seafloor displacements, and Boussinesq dispersion effects. Coastal regions directly facing the segments have the highest exposures with <2 min arrival times, highlighting the major control of wave directivity and the need for rapid evacuation strategies. The Negros Trench generates up to 6 m wave height and 7 m/s flow velocity, while the Sulu Trench up to 8 m and 6 m/s. Coastal areas with ≥2 m wave heights typically exhibit a concave morphology with a nearshore width interquartile range of 2–4.5 km. At wider nearshore width (>20 km), wave dissipation results in lower wave heights (<2 m) that underscore accurate nearshore bathymetry in tsunami modeling. This study provides exposure maps of the maximum wave height, flow velocity, and minimum arrival times from rupture scenarios for searching paleotsunami deposits and most importantly for policymakers, local government, and coastal communities to mitigate tsunami hazard risk.