Struktur Kecepatan Seismik di Bawah Gunung Merapi dan Sekitarnya Berdasarkan  Studi Tomografi Seismik Waktu Tempuh

Mohamad Ramdhan; Said Kristyawan; Andry Syaly Sembiring; D Daryono; P Priyobudi

doi:10.14203/risetgeotam2019.v29.1047

Struktur Kecepatan Seismik di Bawah Gunung Merapi dan Sekitarnya Berdasarkan Studi Tomografi Seismik Waktu Tempuh

Mohamad Ramdhan, Said Kristyawan, Andry Syaly Sembiring, D Daryono, P Priyobudi

Abstract

Periode erupsi Gunung Merapi yang relatif pendek menjadi penyebab banyaknya ahli ilmu kebumian meneliti proses yang terjadi, baik di bawah permukaan maupun di bagian puncak gunung api tersebut. Jaringan seismik DOMERAPI yang terdiri dari 53 stasiun seismik digunakan untuk memahami karakteristik reservoir magma utama di bawah Gunung Merapi dengan periode perekaman data dari bulan Oktober 2013 sampai pertengahan bulan April 2015. Sejumlah 464 gempa berhasil dideteksi oleh jaringan seismik DOMERAPI dengan mayoritas gempanya berada di luar jaringan seismik tersebut karena Gunung Merapi pada saat itu berada dalam keadaan tidak aktif. Gempa-gempa yang berada di luar jaringan seimik tersebut digunakan untuk mendeliniasi reservoir magma utama di bawah Gunung Merapi. Reservoir magma utama di bawah Gunung Merapi teridentifikasi pada kedalaman sekitar 15 km di bawah permukaan laut (MSL) yang dicirikan dengan Vp dan rasio Vp/Vs yang tinggi serta Vs yang rendah. Keberadaan reservoir magma dangkal yang berkaitan dengan fluid percolation juga teridentifikasi dengan jelas pada studi ini yang berada pada kedalaman kurang dari 5 km di bawah MSL yang dicirikan dengan Vp yang rendah, rasio Vp/Vs yang tinggi dan Vs yang rendah. Adapun keberadaan reservoir magma dalam Gunung Merapi tidak berhasil diidentifikasi pada studi ini karena keterbatasan resolusi data seismik.

The relatively short eruption period of Merapi volcano is the reason for many earth scientists to investigate the processes that occur both beneath the surface and at the top of the volcano. The DOMERAPI seismic network consisting of 53 seismic stations was installed to understand the characteristics of the main magma reservoir under the volcano with a period of data recording from October 2013 to mid-April 2015. A total of 464 earthquakes were detected by DOMERAPI seismic network with the majority of the earthquake occured outside the seismic network because the volcano was inactive at that time. The earthquakes are used to delineate the main magma reservoir beneath the volcano. The main magma reservoir was identified at a depth of 15 km below mean sea level (MSL,) which is characterized by high Vp, a high Vp/Vs ratio and low Vs. The existence of shallow magma reservoirs related to fluid percolation was also clearly identified in this study which was at a depth of less than 5 km below MSL which was characterized by low Vp, a high Vp/Vs ratio and low Vs. The existence of deep magma reservoir was not identified in this study because of the limited resolution of seismic data.

Keywords

Merapi, DOMERAPI, magma, reservoir, Vp, rasio Vp/Vs, Vs

Full Text:

PDF (Bahasa Indonesia)

References

Budi-Santoso, A., Lesage, P., Dwiyono, S., Sumarti, S., Subandriyo, Surono, Jousset, P., Metaxian, J.-P., 2013. Analysis of the seismic activity associated with the 2010 eruption of Merapi Volcano, Java. Journal of Volcanology and Geothermal Research, Merapi eruption 261, 153–170. https://doi.org/10.1016/j.jvolgeores.2013.03.024

Cahyaningrum, A.P., Nugraha, A.D., Nanang, T.P., 2015. Earthquake hypocenter relocation using double difference method in East Java and surrounding areas, in: AIP Conference Proceedings. p. 030021.

Costa, F., Andreastuti, S., Bouvet de Maisonneuve, C., Pallister, J.S., 2013. Petrological insights into the storage conditions, and magmatic processes that yielded the centennial 2010 Merapi explosive eruption. Journal of Volcanology and Geothermal Research, Merapi eruption 261, 209–235. https://doi.org/10.1016/j.jvolgeores.2012.12.025

Deegan, F., Troll, V., Freda, C., Misiti, V., Chadwick, J.P., McLeod, C., Davidson, J.P., 2010. Magma–carbonate interaction processes and associated CO2 release at Merapi Volcano, Indonesia: insights from experimental petrology. Journal of Petrology 51, 1027–1051.

DeShon, H.R., Thurber, C.H., Rowe, C., 2007. High-precision earthquake location and three-dimensional P wave velocity determination at Redoubt Volcano, Alaska. Journal of Geophysical Research 112. https://doi.org/10.1029/2006JB004751

Drignon, M.J., Bechon, T., Arbaret, L., Burgisser, A., Komorowski, J.-C., Martel, C., Miller, H., Yaputra, R., 2016. Preexplosive conduit conditions during the 2010 eruption of Merapi volcano (Java, Indonesia). Geophysical Research Letters 43, 11,595-11,602. https://doi.org/10.1002/2016GL071153

Eberhart-Phillips, D., 1993. Local earthquake tomography: earthquake source regions. Seismic Tomography: Theory and Practice 613–643.

Evans, J.R., Eberhart-Phillips, D., Thurber, C., 1994. User’s manual for SIMULPS12 for imaging Vp and Vp/Vs; a derivative of the" Thurber" tomographic inversion SIMUL3 for local earthquakes and explosions. US Geological Survey.

Geiger, L., 1912. Probability method for the determination of earthquake epicenters from the arrival time only. Bull. St. Louis Univ 8, 56–71.

Hidayati S, Ishihara K, Iguchi M, Ratdomopurbo, A., 2008. Focal mechanism of volcano-tectonic earthquakes at Merapi volcano, Indonesia. Indonesian Journal of Physics 19, 75–82.

Komorowski, J.-C., Jenkins, S., Baxter, P.J., Picquout, A., Lavigne, F., Charbonnier, S., Gertisser, R., Preece, K., Cholik, N., Budi-Santoso, A., Surono, 2013. Paroxysmal dome explosion during the Merapi 2010 eruption: Processes and facies relationships of associated high-energy pyroclastic density currents. Journal of Volcanology and Geothermal Research, Merapi eruption 261, 260–294. https://doi.org/10.1016/j.jvolgeores.2013.01.007

Koulakov, I., Bohm, M., Asch, G., Lühr, B.-G., Manzanares, A., Brotopuspito, K.S., Fauzi, P., Purbawinata, M.A., Puspito, N.T., Ratdomopurbo, A., Kopp, H., Rabbel, W., Shevkunova, E., 2007. P and S velocity structure of the crust and the upper mantle beneath central Java from local tomography inversion. J. Geophys. Res. 112, B08310. https://doi.org/10.1029/2006JB004712

Lahr, J., 1999. Revised 2012, HYPOELLIPSE: A computer program for determining local earthquake hypocentral parameters, magnitude, and first-motion pattern. US Geol. Surv. Open-File Rept. 99 23.

Lees, J.M., 1992. The magma system of Mount St. Helens: non-linear high-resolution P-wave tomography. Journal of Volcanology and Geothermal Research 53, 103–116. https://doi.org/10.1016/0377-0273(92)90077-Q

Luehr, B.-G., Koulakov, I., Rabbel, W., Zschau, J., Ratdomopurbo, A., Brotopuspito, K.S., Fauzi, P., Sahara, D.P., 2013. Fluid ascent and magma storage beneath Gunung Merapi revealed by multi-scale seismic imaging. Journal of Volcanology and Geothermal Research 261, 7–19.

Mavko, G.M., 1980. Velocity and attenuation in partially molten rocks. Journal of Geophysical Research 85, 5173. https://doi.org/10.1029/JB085iB10p05173

Muksin, U., Bauer, K., Haberland, C., 2013. Seismic Vp and Vp/Vs structure of the geothermal area around Tarutung (North Sumatra, Indonesia) derived from local earthquake tomography. Journal of Volcanology and Geothermal Research 260, 27–42.

Nakajima, J., Matsuzawa, T., Hasegawa, A., Zhao, D., 2001. Three-dimensional structure of Vp, Vs, and Vp/Vs beneath northeastern Japan: Implications for arc magmatism and fluids. Journal of Geophysical Research: Solid Earth 106, 21843–21857.

Nugraha, A.D., Indrastuti, N., Kusnandar, R., Gunawan, H., McCausland, W., Aulia, A.N., Harlianti, U., 2017. Joint 3-D tomographic imaging of Vp, Vs and Vp/Vs and hypocenter relocation at Sinabung volcano, Indonesia from November to December 2013. Journal of Volcanology and Geothermal Research. https://doi.org/10.1016/j.jvolgeores.2017.09.018

Nugraha, A.D., Mori, J., 2006. Three-dimensional velocity structure in the Bungo Channel and Shikoku area, Japan, and its relationship to low-frequency earthquakes. Geophys. Res. Lett. 33, L24307. https://doi.org/10.1029/2006GL028479

Ramdhan, M., Nugraha, A.D., 2013. Study of seismicity around Toba area based on relocation hypocenter result from BMKG catalogue, in: Padjadjaran International Physics Symposium 2013 (PIPS-2013): Contribution of Physics on Environmental and Energy Conservations. AIP Publishing, pp. 242–244.

Ramdhan, M., Widiyantoro, S., Nugraha, A.D., Métaxian, J.-P., Saepuloh, A., Kristyawan, S., Sembiring, A.S., Santoso, A.B., Laurin, A., Fahmi, A.A., 2017a. Relocation of hypocenters from DOMERAPI and BMKG networks: a preliminary result from DOMERAPI project. Earthquake Science. https://doi.org/10.1007/s11589-017-0178-3

Ramdhan, M., Widiyantoro, S., Nugraha, A.D., Saepuloh, A., Métaxian, J.-P., Kristyawan, S., Sembiring, A.S., Santoso, A.B., 2017b. Seismic Travel-time Tomography beneath Merapi Volcano and its Surroundings: A Preliminary Result from DOMERAPI Project, in: IOP Conference Series: Earth and Environmental Science. IOP Publishing, p. 012039.

Ratdomopurbo, A., Poupinet, G., 2000. An overview of the seismicity of Merapi volcano (Java, Indonesia), 1983–1994. Journal of Volcanology and Geothermal Research 100, 193–214. https://doi.org/10.1016/S0377-0273(00)00137-2

Rohadi, S., Widiyantoro, S., Nugraha, A.D., Masturyono, 2013. Tomographic imaging of P- and S-wave velocity structure beneath central Java, Indonesia: Joint inversion of the MERAMEX and MCGA earthquake data. International Journal of Tomography and Statistics 24, 1–16.

Sabtaji, A., Nugraha, A.D., 2015. 1-D seismic velocity model and hypocenter relocation using double difference method around West Papua region, in: AIP Conference Proceedings.

Smyth, H.R., Hall, R., Nichols, G.J., 2008. Cenozoic volcanic arc history of East Java, Indonesia: The stratigraphic record of eruptions on an active continental margin, in: Special Paper 436: Formation and Applications of the Sedimentary Record in Arc Collision Zones. Geological Society of America, pp. 199–222.

Supendi, P., Nugraha, A.D., Puspito, N.T., Widiyantoro, S., Daryono, D., 2018. Identification of active faults in West Java, Indonesia, based on earthquake hypocenter determination, relocation, and focal mechanism analysis. Geosci. Lett. 5, 31. https://doi.org/10.1186/s40562-018-0130-y

Surono, Jousset, P., Pallister, J., Boichu, M., Buongiorno, M.F., Budisantoso, A., Costa, F., Andreastuti, S., Prata, F., Schneider, D., Clarisse, L., Humaida, H., Sumarti, S., Bignami, C., Griswold, J., Carn, S., Oppenheimer, C., Lavigne, F., 2012. The 2010 explosive eruption of Java’s Merapi volcano—A ‘100-year’ event. Journal of Volcanology and Geothermal Research 241–242, 121–135. https://doi.org/10.1016/j.jvolgeores.2012.06.018

Syracuse, E.M., Thurber, C.H., Power, J.A., 2011. The Augustine magmatic system as revealed by seismic tomography and relocated earthquake hypocenters from 1994 through 2009. Journal of Geophysical Research 116. https://doi.org/10.1029/2010JB008129

Thurber, C., 1993. Local earthquake tomography: velocities and Vp/Vs—theory in Seismic Tomography: Theory and Practice pp. 563–583 eds Iyer HM, Hirahara K. Chapman & Hall London.

Thurber, C., Eberhart-Phillips, D., 1999. Local earthquake tomography with flexible gridding. Computers & Geosciences 25, 809–818.

Tiede, C., Camacho, A.G., Gerstenecker, C., Fernández, J., Suyanto, I., 2005. Modeling the density at Merapi volcano area, Indonesia, via the inverse gravimetric problem. Geochemistry, Geophysics, Geosystems 6.

van Hinloopen Labberton, D., 1921. Oud-Javaansche gegevens omtrent de vulkanologie van Java.

Wadati, K., 1933. On the travel time of earthquake waves II. Geophys. Mag 7, 101–111.

Wagner, D., Koulakov, I., Rabbel, W., Luehr, B.-G., Wittwer, A., Kopp, H., Bohm, M., Asch, G., Scientists, M., 2007. Joint inversion of active and passive seismic data in Central Java. Geophysical Journal International 170, 923–932.

Waldhauser, F., 2001. hypoDD-A Program to Compute Double-Difference Hypocenter Locations (USGS Numbered Series No. 2001–113), Open-File Report.

Waldhauser, F., Ellsworth, W. L., 2000. A Double-Difference Earthquake Location Algorithm: Method and Application to the Northern Hayward Fault, California. Bulletin of the Seismological Society of America 90, 1353–1368. https://doi.org/10.1785/0120000006

Widiyantoro, S., Ramdhan, M., Métaxian, J.-P., Cummins, P.R., Martel, C., Erdmann, S., Nugraha, A.D., Budi-Santoso, A., Laurin, A., Fahmi, A.A., 2018. Seismic imaging and petrology explain highly explosive eruptions of Merapi Volcano, Indonesia. Scientific Reports 8, 13656. https://doi.org/10.1038/s41598-018-31293-w

DOI: http://dx.doi.org/10.14203/risetgeotam2019.v29.1047