KAJIAN KERENTANAN TANAH BERDASARKAN ANALISIS HVSR DI DAERAH SEMBURAN LUMPUR SIDOARJO DAN SEKITARNYA, JAWA TIMUR, INDONESIA
DOI:
https://doi.org/10.31172/jmg.v17i1.398Keywords:
Lusi, HVSR, frekuensi natural, amplifikasi tanah, index kerentananAbstract
Aluvium merupakan fitur geologi yang memiliki sifat rentan terhadap pengaruh gempabumi. Daerah Porong dan sekitarnya tempat semburan Lumpur Sidoarjo (Lusi) terjadi merupakan daerah dataran yang ditutupi oleh endapan aluvium Delta Brantas, sehingga daerah ini merupakan zona lemah yang rentan terhadap pengaruh gempabumi. Hal ini diperkuat dengan adanya sesar Watukosek di daerah tersebut. Dengan tujuan untuk membuktikan hal tersebut maka dilakukan observasi seismik dengan cara memasang 71 stasiun pengamat gempabumi temporal yang tersebar di daerah Sidoarjo dan sekitarnya. Hasil analisis Horizontal Vertical Spectral Ratio (HVSR) terhadap data seismik diperoleh sebaran frekuensi natural bawah permukaan lebih rendah di daerah Lusi yaitu 0,4Hz. Hasil analisis juga mengungkap bahwa di daerah tersebut mempunyai amplifikasi tanah sebesar 5,2 dan tingkat kerentanan tanah sebesar 56, lebih tinggi dibandingkan dengan daerah lain di sekitarnya. Karena letaknya di zona lemah, maka berimplikasi bahwa Lusi menjadi sensitif terhadap gangguan luar misalnya dampak kejadian gempabumi menjadi lebih besar pada daerah ini. Alluvium is a geological feature characterized by high risk vulnerability influenced by the earthquakes. Porong and surrounding areas where the eruption of Lumpur Sidoarjo’s (Lusi) occurred are areas covered by alluvium sediment of Brantas Delta, as consequences this area is a weak zone characterized by high risk vulnerability as well. This is also supported by the present of Watukosek fault system in this area. To proved, we deployed 71 temporary seismic stations distributed in and around Sidoarjo area. The Horizontal Vertical Spectral Ratio (HVSR) analysis revealed that the natural frequency in Lusi area is about 0.4Hz, this is lower than other part areas. The analysis also revealed that this area has soil amplification about 5.2 and soil vulnerability index about 56, these are higher compared with other part areas. These results support that this area is a weak zone. Because of its location in a weak zone, this implies that Lusi became sensitive to external perturbation for example the earthquake events would have greater impact to this area.Downloads
Published
2023-10-17
How to Cite
Karyono, K., Syafri, I., Abdurrokhim, A., Masturyono, M., Rohadi, S., Arifin, J., Sudrajat, A., Mazzini, A., Hadi, S., & Agustya, A. (2023). KAJIAN KERENTANAN TANAH BERDASARKAN ANALISIS HVSR DI DAERAH SEMBURAN LUMPUR SIDOARJO DAN SEKITARNYA, JAWA TIMUR, INDONESIA. Jurnal Meteorologi Dan Geofisika, 17(1). https://doi.org/10.31172/jmg.v17i1.398
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