The Flores back-arc thrust is an active earthquake
source in northern Flores Island, and this trench extends from Bali to East
Flores. On December 12, 1992, there was an earthquake that caused a massive
tsunami. The tsunami that hit along the northern coast of Flores caused many
economic and infrastructure damages and loss of life. The field survey
measurements indicate that the highest tsunami was 26 m in northern coast of
the Flores, revealing significantly high tsunami run-ups which might be caused
by landslides because there were some evidences of landslide slumps in several
areas.
This study reproduces the tsunami propagation and inundation for the 1992
Flores tsunami and compares the numerical results with the observed data
obtained by the field survey. We applied the numerical simulation using a
finite difference TUNAMI code that solves the non-linear shallow water
equations. We used BATNAS bathymetric data and DEMNAS topographic data, which
were provided by Indonesia Geospatial Agency for two-layer computations to
simulate tsunamis form the fault models and three-layer computations for fault
and landslide models. We also propose a scenario earthquake for creating a
tsunami hazard map with a reference fault model from the previous study.
Using the data we collected, we have successfully performed the tsunami
modeling for wave propagation to the northern coast of Flores. The simulated
tsunami by using the three-layer computations with the fault and landslide
models generated higher tsunamis than the two-layer computations only with the
fault models. It is emphasized that the landslide will impact the tsunami
generation higher than the fault only. Besides, we also obtained the maximum
tsunami run-up heights and inundation distances. This study will bring many
advantages to enhance the source input for tsunami simulations since we found that
the results are applicable to create the tsunami hazard map in the Flores area.
Keywords: 1992 Flores Earthquake and Tsunami, Earthquake Fault and Landslide Model, Tsunami Hazard Map