Tjipto Prastowo
Research Center for Earth Science Studies, Physics Department, Universitas Negeri Surabaya

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A simple parameterization for tsunami run-up prediction Latifatul Cholifah; Tjipto Prastowo
Journal of Science and Science Education Vol 1 No 2 (2017): JoSSE Vol. 1 No. 2 (November 2017)
Publisher : Faculty of Science and Mathematics, Universitas Kristen Satya Wacana

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24246/josse.v1i2p7-13

Abstract

The linear shallow-water approximation is commonly used to describe tsunami propagation, where the wave is assumed as a long surface gravity wave. The evolution of wave height during its propagation from offshore to onshore is a classic problem. When arriving at a shoreline, the increased wave height causes severe destruction on infrastructures and fatalities. This problem has then been an important issue within the context of disaster risk reduction as it gives rise to the importance of tsunami run-up prediction. Using maximum run-up data from past events, we tested the applicability of the Green’s law based on shoaling only to calculate run-ups and found that the basic Green’s law was in doubt. Then, we examined energy density conservation involving refraction effect but no dissipation and derived a simple formula for parameterizing run-up height. Detailed descriptions on factors affecting run-ups, such as complex bathymetry and topography are not yet considered in the current study. The aim of this study is therefore to determine whether the modified Green’s law is applicable for tsunami run-up prediction using local water depths as external parameters and ray spacing widths in the normal direction of wave fronts related to refraction. The results are consistent with the measured run-ups, where approximately 70% of total points of observations confirm the modified Green’s law with a reasonable accuracy.
Accurate local magnitude prediction for small to moderate earthquakes using rapid calculations of P-wave dominant period Tjipto Prastowo; Berla Maghda Putri Mahanani; Latifatul Cholifah; La Ode Ngkoimani; La Ode Safiuddin
Journal of Science and Science Education Vol 1 No 2 (2017): JoSSE Vol. 1 No. 2 (November 2017)
Publisher : Faculty of Science and Mathematics, Universitas Kristen Satya Wacana

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24246/josse.v1i2p15-20

Abstract

This study examines mechanisms of rapid and accurate determination of local magnitude Mpd for small to moderate events that occurred in West Sulawesi and Central Sulawesi using direct procedures and calculations of the dominant period Td of P-waveforms. Secondary data were collected from Webdc3, comprising earthquake magnitudes in the regions of interest during 2008-2015 measured in MW. The study focuses on earthquake size estimates for local events as a parameter through simple evaluation of a linear equation relating Td to MW. For all the events considered, empirical formulas derived from the random data for estimating the size are, respectively, Mpd = (Td + 6.6799)/1.5199 for West Sulawesi and Mpd = (Td + 3.3648)/0.8464 for Central Sulawesi. Each was used to recalculate events in the two regions. The results were compared to the reference provided by the Global CMT catalog. The results are consistent with the reference having a standard deviation of up to 0.2, showing evidence of no significant difference in magnitude determination between the method proposed in the current study and that of the Global CMT. This suggests that rapid and accurate magnitude determination is best predicted by the empirical formula developed for each region in this study for future use of disaster risk reduction program.