We study source characteristics of the September 28, 2017 Mw 7.5 Palu (Sulawesi, Indonesia) earthquake that occurred in central Sulawesi and triggered devastating tsunami waves along the coastal plains of the island. We apply point-source teleseismic P- and SH-body waveform inversion and kinematic slip inversion techniques to obtain double-couple source mechanism and comprehensive finite-fault slip model of the source. The overall results show a strike-slip faulting mechanism (strike: 353° ± 5°, dip: 65° ± 5° and rake angles: − 4° ± 5°) with a small amount of dip-slip component at a shallow focal depth of 16 ± 2 km associated with the NW–SE trending left-lateral Palu-Koro strike-slip fault in the central Sulawesi region. The P- wave first motion polarity readings recorded at near-field and regional seismic stations are found to be reasonably consistent with the source mechanism solution of the earthquake and estimated error limits. We have extensively studied and considered the rupture velocity to be about 4.1 km/s during the slip inversion as previously proposed by seismological and geodetic studies for this event. The obtained finite-fault slip distribution model displays a rupture starting from the hypocentre located at 16 km, and then it propagated south accompanied by high amount of displacement, and reached the surface. The model has two slip-patches of 2.0–4.0 m at north of the fault plane, and 5.0–6.3 m at south near Palu city, which is very well matched with the observed damage and destruction related to the earthquake. The fault length and width, average slip and stress drop values are estimated to be 150 km, 45 km, 1.5 m and 13 bars, respectively. We have also obtained total source duration to be about 40 s with the most of seismic energy released at 10 s and 25 s. Furthermore, a small dip-slip component is evidently observed from both source models, and we suggest that this oblique shear which reflects the bending of slip vector along the strike direction could be comparatively responsible for tsunami generation along the left-lateral Palu-Koro Fault. The validation of this hypothesis could be done by evaluating the results of the mathematical tsunami simulations based on the comprehensive non-uniform slip models along with a high-resolution bathymetry data, which provides the details of the continental shelf in Palu bay.
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Aki, K. (1972). Earthquake mechanism. Tectonophysics, 13, 423–446.
Arikawa, T., Muhari, A., Okumura, Y., Dohi, Y., Afriyanto, B., Sujatmiko, K. A., et al. (2018). Coastal subsidence induced several tsunamis during the 2018 Sulawesi earthquake. Journal of Disaster Research. https://doi.org/10.20965/jdr.2018.sc20181204.
Bao, H., Ampuero, J.-P., Meng, L., Fielding, E. J., Liang, C., Milliner, C. W. D., et al. (2019). Early and persistent supershear rupture of the 2018 magnitude 7.5 Palu earthquake. Nature Geoscience. https://doi.org/10.1038/s41561-018-0297-z.
Bassin, C., Laske, G., & Masters, G. N. Y. (2000). The current limits of resolution for surface wave tomography in North America. EOS Trans AGU, 81, F897.
Bellier, O., Sèbrier, M., Beaudouin, T., Villeneuve, M., Braucher, R., Bourlès, D., et al. (2001). High slip rate for a low seismicity along the Palu-Koro active fault in central Sulawesi (Indonesia). Terra Nova, 13(6), 463–470.
Carvajal, M., Araya-Cornejo, C., Sepúlveda, I., Melnick, D., & Haase, J. S. (2019). Nearly instantaneous tsunamis following the Mw 7.5 2018 Palu earthquake. Geophysical Research Letters, 46(10), 5117–5126.
DeMets, C., Gordon, R. G., & Argus, D. F. (2010). Geologically current plate motions. Geophysical Journal International, 181, 1–80. https://doi.org/10.1111/j.1365-246X.2009.04491.x.
DeMets, C., Gordon, R. G., Argus, D. F., & Stein, S. (1990). Current plate motions. Geophysical Journal International, 101(2), 425–478.
Dziewonski, A. M., & Anderson, D. L. (1981). Preliminary reference earth model. Physics of the Earth and Planetary Interiors, 25(4), 297–356.
ESA. (2018). Fault line land movement in Indonesia. European Space Agency—Copernicus Sentinel data processed by ESA, CC BY-SA 3.0 IGO. https://www.esa.int/spaceinimages/Images/2018/10/Fault_line_land_movement_in_Indonesia. Accessed Oct 2018.
Fang, J., Xu, C., Wen, Y., Wang, S., Xu, G., Zhao, Y., et al. (2019). The 2018 Mw 7.5 Palu earthquake: A supershear rupture event constrained by insar and broadband regional seismograms. Remote Sensing, 11, 1330. https://doi.org/10.3390/rs11111330.
Fielding, E. J., Lundgren, P. R., Taymaz, T., Yolsal-Çevikbilen, S., & Owen, S. E. (2013). Fault-slip source models for the 2011 M7.1 Van Earthquake in Turkey from SAR interferometry, pixel offset tracking, GPS and seismic waveform analysis. Seismological Research Letters, 84(4), 579–593.
Frederik, M. C., Adhitama, R., Hananto, N. D., Sahabuddin, S., Irfan, M., Moefti, O., et al. (2019). First results of a bathymetric survey of Palu Bay, Central Sulawesi, Indonesia following the Tsunamigenic Earthquake of 28 September 2018. Pure and Applied Geophysics. https://doi.org/10.1007/s00024-019-02280-7.
Goldstein, P., Dodge, D., Firpo, M., & Minner, L. (2003). SAC2000: Signal processing and analysis tools for seismologists and engineers. In W. H. K. Lee, H. Kanamori, P. C. Jennings, & C. Kisslinger (Eds.), Invited contribution to the IASPEI international handbook of earthquake and engineering seismology. London: Academic Press.
Goldstein, P., & Snoke, A. (2005). SAC Availability for the IRIS Community. Incorporated Institutions for Seismology Data Management Center Electronic Newsletter, 7(1).
Hall, R. (2002). Cenozoic geological and plate tectonic evolution of SE Asia and the SW Pacific: Computer-based reconstructions, model and animations. Journal of Asian Earth Sciences, 20, 353–434.
Hamilton, W. (1979). Tectonics of the Indonesian region (p. 1078). Utah: US Geological Survey, Professional Paper.
Heidarzadeh, M., Muhari, A., & Wijanarto, A. B. (2019). Insights on the source of the 28 September 2018 Sulawesi Tsunami, Indonesia based on spectral analyses and numerical simulations. Pure and Applied Geophysics. https://doi.org/10.1007/s00024-018-2065-9.
Hui, G., Li, S., Wang, P., Suo, Y., Wang, Q., & Somerville, I. D. (2018). Linkage between reactivation of the sinistral strike-slip faults and 28 September 2018 Mw7.5 Palu earthquake, Indonesia. Science Bulletin, 63(24), 1635–1640.
Imamura, F. (1995). Review of tsunami with a finite difference method. Long-wave runup models (pp. 25–42). Singapore: World Scientific Pub Co Inc.
Jamelot, A., Gailler, A., Heinrich, Ph, Vallage, A., & Champenois, J. (2019). Tsunami simulations of the Sulawesi Mw 7.5 event: Comparison of seismic sources issued from a tsunami warning context versus post-event finite source. Pure and Applied Geophysics. https://doi.org/10.1007/s00024-019-02274-5.
Ji, C., Wald, D. J., & Helmberger, D. V. (2002). Source description of the 1999 Hector Mine, California earthquake; Part I: Wavelet domain inversion theory and resolution analysis. Bulletin of the Seismological Society of America, 92(4), 1192–1207.
Kanamori, H. (1994). Mechanics of earthquakes. Annual Review of Earth and Planetary Sciences, 22, 207–237.
Katili, J. A. (1978). Past and present geotectonic position of Sulawesi, Indonesia. Tectonophysics, 45(4), 289–322.
Kennett, B. L. N., & Engdahl, E. R. (1991). Traveltimes for global earthquake location and phase identification. Geophysical Journal International, 105(2), 429–465.
Kikuchi, M., & Kanamori, H. (1991). Inversion of complex body waves—III. Bulletin of the Seismological Society of America, 81, 2335–2350.
Mikami, T., Shibayama, T., Esteban, M., Takabatake, T., Nakamura, R., Nishida, Y., et al. (2019). Field survey of the 2018 Sulawesi tsunami: Inundation and run-up heights and damage to coastal communities. Pure and Applied Geophysics. https://doi.org/10.1007/s00024-019-02258-5.
Molnar, P., & Lyon-Cáen, H. (1989). Fault plane solutions of earthquakes and active tectonics of the Tibetan Plateau and its margins. Geophysical Journal International, 99, 123–153.
Muhari, A., Imamura, F., Arikawa, T., & Afriyanto, B. (2018). Finding of the unexpected tsunami due to the strike-slip fault at central Sulawesi, Indonesia on 28 September 2018, from the preliminary field survey at Palu. http://irides.tohoku.ac.jp/media/files/earthquake/eq/2018_sulawesi_eq/IRIDeS_report_Palu_survey_20181015.pdf.
Okuwaki, R., Yagi, Y., & Shimizu, K. (2018). rokuwaki/2018PaluIndonesia: v2.0 (Version v2.0). Zenodo. http://doi.org/10.5281/zenodo.1469007.
Omira, R., Dogan, G. G., Hidayat, R., Husrin, S., Prasetya, G., Anunziato, A., et al. (2019). The September 28th, 2018, tsunami in Palu-Sulawesi, Indonesia: A post-event field survey. Pure and Applied Geophysics. https://doi.org/10.1007/s00024-019-02145-z.
Pakoksung, K., Suppasri, A., Imamura, F., Athanasius, C., Omang, A., & Muhari, A. (2019). Simulation of the submarine landslide tsunami on 28 September 2018 in Palu Bay, Sulawesi Island, Indonesia, using a two-layer model. Pure and Applied Geophysics. https://doi.org/10.1007/s00024-019-02235-y.
Paulik, R., Gusman, A., Williams, J. H., Pratama, G. M., Lin, S., Prawirabhakti, A., et al. (2019). Tsunami hazard and built environment damage observations from Palu City after the September 28 2018 Sulawesi earthquake and tsunami. Pure and Applied Geophysics. https://doi.org/10.1007/s00024-019-02254-9.
Pelinovsky, E., Yuliadi, D., Prasetya, G., & Hidayat, R. (1997). The 1996 Sulawesi tsunami. Natural Hazards, 16, 29–38.
Putra, P. S., Aswan, A., Maryunani, K. A., Yulianto, E., & Kongko, W. (2019). Field survey of the 2018 Sulawesi tsunami deposits. Pure and Applied Geophysics. https://doi.org/10.1007/s00024-019-02181-9.
Saltogianni, V., Taymaz, T., Yolsal-çevikbilen, S., Eken, T., Moschas, F., & Stiros, S. (2017). Fault model for the 2015 Leucas (Aegean Arc) earthquake: Analysis based on seismological and geodetic observations. Bulletin of the Seismological Society of America. https://doi.org/10.1785/0120160080.
Sassa, S., & Tagakawa, T. (2019). Liquefied gravity flow-induced tsunami: First evidence and comparison from the 2018 Indonesia Sulawesi earthquake and tsunami disasters. Landslides, 16(1), 195–200.
Socquet, A., Hollingsworth, J., Pathier, E., & Bouchon, M. (2019). Evidence of supershear during the 2018 magnitude 7.5 Palu earthquake from space geodesy. Nature Geoscience. https://doi.org/10.1038/s41561-018-0296-0.
Socquet, A., Simons, W., Vigny, C., McCaffrey, R., Subarya, C., Sarsito, D., et al. (2006). Microblock rotations and fault coupling in SE Asia triple junction (Sulawesi, Indonesia) from GPS and earthquake slip vector data. Journal of Geophysical Research, 111, B08409.
Soloviev, S. L., Go, Ch N, & Kim, Kh S. (1992). Catalogue of tsunamis in the Pacific 1969–1982. Moscow: Soviet Geophysical Committee.
Spencer, J. E. (2011). Gently dipping normal faults identified with Space Shuttle radar topography data in central Sulawesi, Indonesia, and some implications for fault mechanics. Earth and Planetary Science Letters, 308(3–4), 267–276.
Syamsidik, Benazir, Umar, M., Margaglio, G., & Fitrayansyah, A. (2019). Post-tsunami survey of the 28 September 2018 tsunami near Palu Bay in Central Sulawesi, Indonesia: Impacts and challenges to coastal communities. International Journal of Disaster Risk Reduction, 38, 101229.
Tagaki, H., Pratama, M. B., Shota, K., Miguel, E., Aránguiz, R., & Ke, B. (2019). Analysis of generation and arrival time of landslide tsunami to Palu City due to the 2018 Sulawesi Earthquake. Landslides. https://doi.org/10.1007/s10346-019-01166-y.
Tan, O., & Taymaz, T. (2006). Active tectonics of the Caucasus: Earthquake source mechanisms and rupture histories obtained from inversion of teleseismic body waveforms. In: Post-Collisional Tectonics and Magmatism in the Mediterranean Region and Asia. Geological Society of America, Special Paper, 409, 531–578.
Taymaz, T., Jackson, J. A., & McKenzie, D. (1991). Active tectonics of the North and Central Aegean Sea. Geophysical Journal International, 106, 433–490.
Taymaz, T., Jackson, J. A., & Westaway, R. (1990). Earthquake mechanisms in the Hellenic Trench near Crete. Geophysical Journal International, 102, 695–731.
Taymaz, T., & Price, S. (1992). The 1971 May 12 Burdur earthquake sequence, SW Turkey: A synthesis of seismological and geological observations. Geophysical Journal International, 108, 589–603.
Tsuji, Y., Imamura, F., Matsumoto, H., Synolakis, C. E., Nanang, P. T., Harada, S., et al. (1995). Field survey of the east Java earthquake and tsunami of June 3, 1994. Pure and Applied Geophysics, 144, 839–854.
Ulrich, T., Vater, S., Madden, E.H., Behrens, J., van Dinther, Y., van Zelst, I., Fielding, E.J., Liang, C., & Gabriel, A.-A. (2019). Coupled, Physics-based modelling reveals earthquake displacements are critical to the 2018 Palu, Sulawesi Tsunami. https://doi.org/10.31223/osf.io/3bwqa.
Valkaniotis, S., Ganas, A., Tsironi, V., & Barberopoulou, A. (2018). A preliminary report on the M7.5 Palu earthquake co-seismic ruptures and landslides using image correlation techniques on optical satellite data, EMSC report.
Walpersdorf, A., Vigny, C., Subarya, C., & Manurung, P. (1998). Monitoring of the Palu-Koro Fault (Sulawesi) by GPS. Geophysical Reseacrh Letters, 25, 2313–2316.
Wessel, P., & Smith, W. H. F. (1998). New, improved version of generic mapping tools released. EOS Trans AGU, 79(47), 579.
Yagi, Y., & Kikuchi, M. (2000). Source rupture process of the Kocaeli, Turkey, earthquake of August 17, 1999, obtained by joint inversion of near-field data and teleseismic data. Geophysical Research Letters, 27, 1969–1972.
Yagi, Y., Nishimura, N., & Kasahara, A. (2012). Source process of the 12 May 2008 Wenchuan, China, earthquake determined by waveform inversion of teleseismic body waves with a data covariance matrix. Earth Planets Space, 64, E13–E16.
Yagi, Y., Okuwaki, R., Enescu, B., Hirano, S., Yamagami, Y., Endo, S., et al. (2014). Rupture process of the 2014 Iquique Chile Earthquake in relation with the foreshock activity. Geophysical Research Letters, 41, 4201–4206.
Yolsal-Çevikbilen, S., & Taymaz, T. (2012). Earthquake source parameters along the Hellenic subduction zone and numerical simulations of historical tsunamis in the Eastern Mediterranean. Tectonophysics, 536(537), 61–100.
Yolsal-Çevikbilen, S., Ulutaş, E., & Taymaz, T. (2019). Source models of the 2012 Haida Gwaii (Canada) and 2015 Illapel (Chile) earthquakes and numerical simulations of related tsunamis. Pure and Applied Geophysics (PAAG), 176(7), 2995–3033.
Zhang, Y., Chen, Y.-T., & Feng, W. (2019). Complex multiple-segment ruptures of the 28 September 2018, Sulawesi, Indonesia, earthquake. Science Bulletin, 64, 650–652.
Zwick, P., McCaffrey, R., & Abers, G. (1994). MT5 Program, in Bibliographic References and BSSA Database (August 1994). IASPEI Software Library, vol. 4. http://www.iaspei.org/.
We would like to thank Turkish Academy of Sciences (TÜBA) in the framework for Young Scientist Award Program (TÜBA-GEBIP), İstanbul Technical University Research Fund (İTÜ-BAP), Turkish National Scientific Technological Foundation (TÜBİTAK), and Alexander von Humboldt Foundation (AvH) for their financial support. Teleseismic body waveform data used are from the International Federation of Digital Seismograph Networks (FDSN) and the Global Digital Seismograph Network (GDSN) stations and archived at the IRIS-DMC, http://ds.iris.edu/wilber3. The Generic Mapping Tools (GMT; Wessel and Smith 1998) and SAC2000 software packages (Goldstein et al. 2003; Goldstein and Snoke 2005) were used for the preparation of the figures and for processing conventional earthquake data, respectively. We appreciate Yuji Yagi’s generous permission to use the kinematic slip inversion code to analyze rupture history and slip distribution models. We also thank two anonymous reviewers and Alexander Rabinovich (Editor-in-Chief) for their constructive comments and suggestions which have improved this manuscript.
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Yolsal-Çevikbilen, S., Taymaz, T. Source Characteristics of the 28 September 2018 Mw 7.5 Palu-Sulawesi, Indonesia (SE Asia) Earthquake Based on Inversion of Teleseismic Bodywaves. Pure Appl. Geophys. 176, 4111–4126 (2019). https://doi.org/10.1007/s00024-019-02294-1
- finite-fault slip inversion
- source parameters
- the Palu-Koro fault