A Model of Seismic Velocity Structure Derived from Local Tomographic Inversion Beneath the Jailolo Mountain Complex, North Maluku

Wandono Wandono; Bayu Merdeka Tri Fristiyan Nanda; Nova Heryandoko; Karyono Karyono

doi:10.33394/j-ps.v14i3.21363

Authors

Wandono Wandono State College for Meteorology Climatology and Geophysics
Bayu Merdeka Tri Fristiyan Nanda Ternate Geophysical Station
Nova Heryandoko The Agency for Meteorology Climatology and Geophysics
Karyono Karyono State College for Meteorology Climatology and Geophysics

DOI:

https://doi.org/10.33394/j-ps.v14i3.21363

Keywords:

Local-scale seismic tomography, Earthquake swarms, Volcanic activity, Mount Jailolo

Abstract

In late 2015, the Mount Jailolo complex was shaken by a prolonged earthquake swarm. Mount Jailolo is an ancient volcano that has shown no activity since 1600. The occurrence of an earthquake swarm in the region has sparked speculation about a resurgence of volcanic activity at this ancient volcano. To study the swarm phenomenon in Jailolo, a local scale high-resolution seismic tomography study with a nonlinear approach was conducted beneath the Mount Jailolo complex —a first of its kind. The primary objective of this study is to image the P- and S-wave velocity structures in the upper crust down to a depth of 15 km in 3D for the Mount Jailolo complex (0.8°–1.3° N; 127.2°–127.9° E). Using data from 524 microearthquakes that occurred beneath the Mount Jailolo complex, collected by the GFZ-Potsdam and BMKG collaborative seismic network over a 12-month period, a negative S-wave velocity anomaly was detected beneath Mount Jailolo at depths below 5 km, which is believed to correspond to a magma chamber. The upper crust at depths of less than 5 km is dominated by positive P- and S-wave velocity anomalies, except in the Idamdehe Caldera Complex, west of the Mount Jailolo complex, which is characterized by negative velocity anomalies. The positive velocity anomalies are believed to represent igneous rocks resulting from past volcanic activity at Mount Jailolo.

References

Eberhart-Phillips, D. (1993). Local earthquake tomography: Earthquake source regions. In H. M. Iyer & K. Hirahara (Eds.), Seismic tomography: Theory and practice (pp. 614–643). Chapman and Hall.

Hall, R., & Wilson, M. E. J. (2000). Neogene sutures in eastern Indonesia. Journal of Asian Earth Sciences, 18(6), 781–808. https://doi.org/10.1016/S1367-9120(00)00040-7

Hanka, W., Saul, J., Weber, B., Becker, J., Harjadi, P., Fauzi, & GITEWS Seismology Group. (2010). Real-time earthquake monitoring for tsunami warning in the Indian Ocean and beyond. Natural Hazards and Earth System Sciences, 10, 2611–2622. https://doi.org/10.5194/nhess-10-2611-2010

Humphreys, E., & Clayton, R. W. (1988). Adaptation of back projection tomography to seismic travel time problems. Journal of Geophysical Research: Solid Earth, 93(B2), 1073–1085. https://doi.org/10.1029/JB093iB02p01073

Kennett, B. L. N., & Engdahl, E. R. (1991). Traveltimes for global earthquake location and phase identification. Geophysical Journal International, 105(2), 429–465. https://doi.org/10.1111/j.1365-246X.1991.tb06724.x

Kissling, E., Ellsworth, W. L., Eberhart-Phillips, D., & Kradolfer, U. (1994). Initial reference models in local earthquake tomography. Journal of Geophysical Research: Solid Earth, 99(B10), 19,635–19,646.

Kissling, E., Kradolfer, U., & Maurer, H. (1995). VELEST user’s guide. Institute of Geophysics, ETH Zurich.

Koulakov, I. (2009). LOTOS code for local earthquake tomographic inversion: Benchmarks for testing tomographic algorithms. Bulletin of the Seismological Society of America, 99(1), 194–214. https://doi.org/10.1785/0120080013

Koulakov, I., Gordeev, E. I., Dobretsov, N. L., Vernikovsky, V. A., Senyukov, S., Jakovlev, A., & Jaxybulatov, K. (2013). Rapid changes in magma storage beneath the Klyuchevskoy group of volcanoes inferred from time-dependent seismic tomography. Journal of Volcanology and Geothermal Research, 263, 75–91. https://doi.org/10.1016/j.jvolgeores.2012.10.014

Koulakov, I., Jakovlev, A., & Luehr, B. G. (2009). Anisotropic structure beneath central Java from local earthquake tomography. Geochemistry, Geophysics, Geosystems, 10(2). https://doi.org/10.1029/2008GC002109

Koulakov, I., Yudistira, T., Luehr, B. G., & Wandono. (2009). P, S velocity and Vp/Vs ratio beneath the Toba caldera complex, northern Sumatra, from local earthquake tomography. Geophysical Journal International, 177(3), 1121–1139. https://doi.org/10.1111/j.1365-246X.2009.04114.x

Kukarina, E., West, M., Keyson, L. H., Koulakov, I., Tsibizov, L., & Smirnov, S. (2017). Focused magmatism beneath Uturuncu volcano, Bolivia: Insights from seismic tomography and deformation modeling. Geosphere, 13(6), 1855–1866.

McCaffrey, R., Silver, E. A., & Raitt, R. W. (1980). The tectonic and geologic evolution of Southeast Asian seas and islands (Geophysical Monograph Series, Vol. 23).

Mogi, K. (1963). Some discussions on aftershocks, foreshocks and earthquake swarms: The fracture of a semi-infinite body caused by an inner stress origin and its relation to the earthquake phenomena. Bulletin of the Earthquake Research Institute, 41, 615–658.

Passarelli, L., Heryandoko, N., Cesca, S., Rivalta, E., Rasmid, Rohadi, S., Dahm, T., & Milkereit, C. (2018). Magmatic or not magmatic? The 2015–2016 seismic swarm at the long-dormant Jailolo volcano, West Halmahera, Indonesia. Frontiers in Earth Science, 6, Article 79. https://doi.org/10.3389/feart.2018.00079

Pranata, B., Ramdhan, M., Hanif, M., Sulaiman, M. I., Maulana, M. P., Wandono, Widiyantoro, S., Suhardja, S. K., Hidayat, E., Supendi, P., Kusnandar, R., & Setyonegoro, W. (2023). Seismic imaging beneath Sumatra Island and its surroundings, Indonesia, from local-regional P-wave earthquake tomography. Rudarsko-Geolosko-Naftni Zbornik, 38(3), 119–132. https://doi.org/10.17794/rgn.2023.3.10

Putri, Y. T., Heryandoko, N., Wandono, Marulak, R., Suwardi, Zulfikar, Barkah, Yuniarto, Pary, L., & Kamaruddin, B. (2016). Relokasi dan distribusi b-value gempabumi swarm Jailolo, Halmahera Barat. Jurnal Meteorologi dan Geofisika, 17(3).

Ramdhan, M. (2018). Rekonstruksi tomografi struktur 3-D kecepatan dan atenuasi gelombang seismik di bawah Gunung Merapi dan sekitarnya [Doctoral dissertation, Institut Teknologi Bandung].

Sudiyanto, A. S. (2014). Interpretasi struktur kerak dan mantel atas di bawah Provinsi Bengkulu menggunakan tomografi seismik waktu tunda [Master’s thesis, Universitas Gadjah Mada].

Thurber, C. H. (1993). Local earthquake tomography velocities and Vp/Vs theory. In H. M. Iyer & K. Hirahara (Eds.), Seismic tomography: Theory and practice (pp. 563–583). CRC Press.

Vargas, C. A., Koulakov, I., Jaupart, C., Gladkov, V., Gomez, E., El Khrepy, S., & Al-Arifi, N. (2017). Breathing of the Nevado del Ruiz volcano reservoir, Colombia, inferred from repeated seismic tomography. Scientific Reports, 7, Article 46094. https://doi.org/10.1038/srep46094

Wandono. (2007). Studi tomografi seismik non-linier lokal untuk Kompleks Kaldera Toba dan sekitarnya [Doctoral dissertation, Institut Teknologi Bandung].

Wandono, Widiyantoro, S., Ibrahim, G., & Triyoso, W. (2006). Citra upwelling di bawah Sumatera Utara berdasarkan model tomografi gelombang P dan S. Jurnal Geofisika, 1, 6–10.

Wandono, W., Ramdhan, M., Aulia, A. N., Pangestu, A. B., Hidayat, E., Syuhada, S., Widiyantoro, S., Rawlinson, N., Anggono, T., Pranata, B., Mukti, M. M., & Maulana, M. P. (2025). Seismic velocity structure beneath the western Java region, Indonesia, from local earthquake tomography. Journal of Volcanology and Geothermal Research, 468, Article 108472. https://doi.org/10.1016/j.jvolgeores.2025.108472

Widiyantoro, S., & Van Der Hilst, R. (1997). Mantle structure beneath Indonesia inferred from high-resolution tomographic imaging. Geophysical Journal International, 130(1), 167–182. https://doi.org/10.1111/j.1365-246X.1997.tb00996.x