Muh Sarkowi
Program Studi Teknik Geofisika, Fakultas Teknik Universitas Lampung, , Jl. Prof. Soemantri Brodjonegoro No. 1, Bandar Lampung, Telp. (0721)703475-708.

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Interpretasi Struktur Bawah Permukaan Daerah Gunung Merbabu – Merapi Berdasarkan Pemodelan 3D Anomali Bouguer Sarkowi, Muh
BERKALA FISIKA Vol 13, No 2 (2010): Berkala Fisika, Edisi Khusus
Publisher : BERKALA FISIKA

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Mount Merbabu represent the volcano which keep a lot of mystery because its activity not many known by vulcanology expert. At least existing data about activity of Mount Merbabu cause the its activity characteristic not yet can be expressed surely. Study [of] about characteristic of Mount Merbabu needed to to learn the nature of vulcanisme activity so that action prevetive fall the victim and disaster mitigation can be done early possible.  While the Mount of Merapi represent the most active volcano in the world. In Its activity, eruption Merapi Mount  yield the hot cloud (wedus gembel) with the temperature 3000 º C to  glide the mean reach the distance 4-5 km. In this research we have been done modeling and interpretation of Bouguer anomaly around  Mt. Merapi and Merbabu. Result of research indicate that Mt. Merapi and Merbabu have the negative anomaly which because of existence  magma chamber. The magma chamber in Mt. Merapi have a convex form with the deepnes from 500 – 6000 meter from meas sea level, while the magma chamber in Mt. Merbabu have the same from but rather minimize with the deppnes magma chamber about 1000 – 4000 meter from means sea level.  Magma chamber in Mt. Merapi caontain liquid magma while the solid magma in Mt. Merbabu.   Keywords : Mount Merapi, Mount Merbabu, Gravity
GRAV3D Validation using Generalized Cross-Validation (GCV) Algorithm by Lower Bounds Approach for 3D Gravity Data Inversion Adhi, Mochamad Aryono; Wahyudi, Wahyudi; Suryanto, Wiwit; Sarkowi, Muh
Scientific Journal of Informatics Vol 5, No 2 (2018): November 2018
Publisher : Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/sji.v5i2.16736

Abstract

The completion of gravitational data inversion results in a smooth recovered model. GRAV3D is one software that can be used to solve 3D inversion problems of gravity data. Nevertheless there are still fundamental problems related to how to ensure the validity of GRAV3D to be used in 3D inversion. One approach used is to use lower bounds as inversion parameters. In this study lower bounds are set from  to . The results obtained show that the use of lower bounds decreases resulting in a larger data misfit which means that the more data that meets the tolerance calculation, the better recovered model produced.
PEMODELAN 2 DIMENSI DATA MAGNETOTELLURIK DAERAH PROSPEK PANASBUMI LAPANGAN “JGT” Murdani, Murdani; Sarkowi, Muh
Jurnal Geofisika Eksplorasi Vol 3, No 1 (2017)
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ABSTRAK Metode magnetotelurik (MT) adalah metode sounding elektromagnetik untuk mengetahui struktur bawah permukaan berdasakan nilai tahanan jenis dengan cara melakukan pengukuran pasif  komponen medan listrik (E) dan medan  magnet (H) alam yang berubah terhadap waktu. Hasil pemodelan inversi 1 dimensi dan 2 dimensi pada  33  titik data ukur yang tersebar pada 3 lintasan area penelitian. Dari ketiga lintasan pengukuran terdapat lapisan yang memliki nilai resistivitas rendah diduga sebagai batuan penudung nulai resistivitas 4 Ωm dengan kedalaman 500 – 1000 m Resistivitas sedang dengan rentang nilai resistivitas 21 Ωm – 53 Ωm dengan kedalaman lebih dari 1000 m merupakan batuan reservoir. Zona yang ketiga memiliki lapisan paling resistif dengan nilai resistivitas 76 Ωm – 159 Ωm merupakan batuan dasar (sumber panas) yang terletak pada kedalaman lebih dari 2000 m.  ABSTRACT Magnetotelluric method is an electromagnetic sounding methode to know sub-surface structure based on resistivity value by doing a passive acquitition using natural electric and magnetic field component measurement which change due to time. 1D and 2D inversion modelling result on 33 measurement data point which spreaded on 3 research area line. From all three measurement line, there is a layer which has a low resistivity value which suspected as a cap-rock started from 4 Ωm with 500-1000 m depth. Middle resistivity value range started from 21 Ωm – 53 Ωm with more than 1000 m is a reservoir rock. The third zone has the most resistive layer with resistivity value started from 76 Ωm – 159 Ωm is a source rock (hot source) which located at more than 2000 m depth.  Keywords—Magnetotelluric, Geothermal, “JGT” Field
PEMODELAN DAN ANALISA STRUKTUR BAWAH PERMUKAAN DAERAH PROSPEK PANASBUMI KEPAHIANG BERDASARKAN METODE GAYABERAT Sihombing, Roy Bryanson; Sarkowi, Muh; Rustadi, Rustadi
Jurnal Geofisika Eksplorasi Vol 4, No 2 (2018)
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ABSTRAKTelah dilakukan penelitian di daerah Kepahiang menggunakan data gayaberat dengan tujuan mengidentifikasi patahan berdasarkan analisis Second Vertical Derivative (SVD) dan menafsirkan struktur bawah permukaan berdasarkan model inversi 3D dari anomali Bouguer dan anomali residual. Daerah penelitian memiliki anomali Bouguer antara 38 mGal – 74 mGal, dimana nilai anomali Bouguer tinggi memiliki rentang nilai 63,2 mGal – 74 mGal yang berada di arah barat daya daerah penelitian. Sedangkan nilai anomali Bouguer rendah memiliki rentang nilai 38 mGal – 47 mGal yang berada di arah utara daerah penelitian. Untuk mengetahui keberadaan struktur patahan di daerah penelitian, dilakukan filtering Second Vertical Derivative (SVD) pada peta anomali Bouguer, Regional dan Residual. Pola struktur patahan ditunjukkan dengan kontur bernilai nol dan diapit kontur tinggi dan rendah. Dari hasil analisis SVD anomali Bouguer lengkap dan SVD anomali residual terdapat 8 (delapan) patahan, sedangkan dari SVD anomali regional terdapat 4 (empat) patahan. Pemodelan inversi 3D anomali residual dilakukan untuk membuktikan keberadaan patahan yang dianalisis berdasarkan filtering Second Vertical Derivative (SVD). Berdasarkan hasil inversi 3D anomali residual didapatkan satu (1) reservoar di arah utara daerah penelitian dan dua (2) di arah barat daerah penelitian dengan kontras densitas dari -0,0719356 gr/cm3 sampai -0,236053 gr/cm3 dengan kedalaman dari 0 meter sampai 4.705 meter. ABSTRACTResearch has been conducted in Kepahiang area using gravity data with the aim of identify faults based on analysis of the Second Vertical Derivative (SVD) and interpreting structure sub-surface of the based on 3D inverse modelling from Bouguer anomaly and residual anomaly. The research area have an Bouguer anomaly between 38 mGal - 74 mGal, where the high Bouguer anomaly value has a value range of 63,2 mGal - 74 mGal located in the southwest direction of the research area. Whereas the low Bouguer anomaly value has a range of values 38 mGal - 47 mGal located in the north of the research area. To know the existence of fault structure in research area, conducted filtering Second Vertical Derivative (SVD) on the map Bouguer anomaly, regional and residual. The structure faulting is shown with contour of zero and between the contours of high and low. From the analysis of SVD complete anomaly Bouguer and SVD residual anomaly there are 8 (eight) faulting, while from SVD regional anomaly there are 4 (four) fault. 3D inversion modeling of the residual anomaly was done to prove the existence of the fault analyzed based on filtering Second Vertical Derivative (SVD). Based on the results of inversion 3D residual anomaly been gained one (1) reservoir in a northern direction research area and two (2) in the direction of west the research area by a contrast the density of -0,0719356 gr/cc      until-0,236053 gr/cc with a depth of 0 meters up to 4.705 meters. Keywords: 3D inverse modelling, geothermal, gravity, Kepahiang, SVD.
PEMANTAUAN PROSES INJEKSI AIR PADA LAPANGAN “SMR” CEKUNGAN SUMATERA TENGAH BERDASARKAN DATA ANOMALI TIME-LAPSE MICROGRAVITY Pratiwi, Dian; Sarkowi, Muh; Haerudin, Nandi; Wiyono, Agung
Jurnal Geofisika Eksplorasi Vol 4, No 1 (2018)
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ABSTRAK Telah dilakukan penelitian tentang monitoring proses injeksi pada lapangan “SMR” Cekungan Sumatera Tengah dengan menggunakan metode gayaberat mikro. Metode time-lapse microgravity merupakan pengembangan dari metode gayaberat (x,y,z) dengan menambahkan dimensi keempat yakni waktu (t). Monitoring dilakukan pada lapangan-lapangan produksi yang telah melakukan EOR (Enchanced Oil Recovery) yakni proses menginjeksikan air kedalamreservoar untuk mendorong dan menguras sisa-sisa minyak pada pori-poribatuan reservoar ke sumur produksi.Pengolahan data gayaberat mikro dilakukan dengan mencari selisih nilai gayaberat observasi antara pengukuran kedua dan pertama, selanjutnya melakukan analisis spektral untuk memisahkan anomali pada kedalaman reservoar dan noise.Anomali time-lapse microgravity memiliki nilai sebesar-132.28 µGal hingga 0.053 mGal.Anomali positif berhubungan dengan proses injeksi, sedangkan anomali negatif berhubungan dengan proses produksi pada daerah penelitian. Analisis filtering menunjukan terdapat dua zona dinamika fluida, yakni  akibat proses dinamika air permukaan (air tanah diatas reservoar) dan yang terjadi pada reservoar. Zona pengurangan fluida terjadi pada daerah-daerah dengan jumlah sumur produksi lebih banyak dari sumur injeksi.Pengurangan densitas terjadi pada lapisan reservoar yakni pada kedalaman 600 m hingga 1000 m dengan nilai maksimum pengurangan sebesar -3.1x10-3 gr/cm3.Model inversi gayaberat time-lapse menunjukan adanya beberapa sumur injeksi yang kurang efektif sehingga perlu dihentikan injeksinya.  ABSTRACT                     There had been done a regional research about monitoring of injection process in "SMR" field of Central Sumatera Basin using microgravity method. The time-lapse microgravity method is the development of the gravity method (x, y, z) by adding the fourth dimension of time (t). Monitoring is carried out on production fields that have performed EOR (Enchanced Oil Recovery) ie the process of injecting water into the reservoir to push and drain the remnants of oil in the pores of the reservoir rock to the production well. The microgravity data processing is done by finding the difference between observed gravity values between the first and the second measurements, then performing the spectral analysis to separate the anomaly at reservoir depth and noise. The time-lapse microgravity anomaly has a value of -132.28 μGal to 54.89 μGal. Positive anomalies are related to the injection process, whereas the negative anomalies are related to the production process in the study area. Filtering analysis shows that there are two zones of fluid dynamics, which is due to the process of surface water dynamics (groundwater above reservoir) and that occurs in the reservoir. Fluid reduction zones occur in areas with more production wells than injection wells. Density reduction occurs in the reservoir layer at a depth of 600 m to 1000 m with a maximum reduction value of -3.1x10-3 gr / cm3. The gravity time-lapse inversion model shows the existence of several injection wells that are less effective and therefore need to be stopped injecting. Keywords— Microgravity, Enchanced Oil Recovery (EOR), Gravity Observation, Spectral Analysis, Density
PEMODELAN 3D DAN ANALISIS KETERSEDIAAN BATUAN GRANIT BERDASARKAN DATA ANOMALI GAYABERAT DI DAERAH TANJUNG ULIE HALMAHERA TENGAH Elviani, Sari; Sarkowi, Muh; Zaenudin, Ahmad
Jurnal Geofisika Eksplorasi Vol 3, No 2 (2017)
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ABSTRAK Telah dilakukan penelitian dengan metode Gayaberat pada daerah Tanjung Ulie Kabupaten Halmahera Tengah Provinsi Maluku Utara. Penelitian ini dilakukan untuk mengindentifikasi keberadaan batuan granit. Batuan granit tersebut akan digunakan untuk bahan kontruksi pembuatan jalan. Dalam penelitian ini data yang diperoleh berupa nilai elevasi dan nilai gayaberat observasi dari lapangan dengan luasan 250 m x 200 m dan spasi jaran 2.5 m. Dilakukan beberapa koreksi gayabeat di antaranya koreksi lintang, koreksi topografi, Koreksi Bouguer dan koreksi terrain untuk memperoleh nilai Anomali Bouguernya. Dari sebaran nilai Anomali yang dikonturkan menggunakan software Surfer maka diperoleh sebaran nilai anomali Bouguer berkisar antara 153,8 mGall – 155,9 . Nilai Anomali tinggi berada pada daerah utara dan timur laut dengan kisaran nilai 155,1 mGall – 155,9 mGall yang diasumsikan sebagai zona target penelitian. Pemodelan inversi 3 Dimensi dengan menggunakan software Grav3D. Dan hasilnya menunjukan bahwa batuan yang memiliki nilai densitas tinggi berada pada daerah utara dan timur laut pada kedalaman 5 m hingga 75 m. Pada metode Second Vertical Derivative nilai nol pada nilai SVD diperkirakan sebagai patahan batuan yang menjadi batas antara batuan target dan batuan di sekitarnya.   ABSTRACT A research was did in Tanjung Ulie, Central Halmahera, North Maluku Province using Gravity method. The purpose of this research was to identificate the presence of granit rocks. The granit rocks itself will be used as material for road construction. In this research, the data which obtained were elevation and observation gravity values from 250 m x 200 m field area and distance space 2,5 m . Anomaly Bouguer was got from gravity corrections, in between the lattitude correction, topography correction, Bouguer correction and terrain correction to obtain the value of Bouguer Anomaly. From the distribution of Anomaly values which contoured using Surfer software then obtained the value of Bouguer Anomaly from 153,8 mGall to 155,9 mGall. The highest Anomaly value was located in the north and north east area with range of Bouguer Anomaly value from 155,1 mGall to 155,9 mGall which assumed as target zone of the research.The 3 dimension inversion modelling was created using Grav3D software and the result shows that the rocks which have high density values located in the north and north east area at depth 7 m untill 75 m . On Second Vertical Derivative method, the zero value on SVD value was estimated as rock fault which become the boundary between target rocks with rocks around it. Keywords— Gravity Method, Bouguer Anomaly, 3D modelling, Second Vertical Derivative, Granite
IDENTIFIKASI BAWAH PERMUKAAN LAPANGAN MINYAK“HUF” SUMATERA SELATAN UNTUK MENDELINIASI STRUKTUR CEKUNGAN HIDROKARBON BERDASARKAN DATA GAYABERAT Setiawan, Ade; Sarkowi, Muh; Mulyatno, Bagus Sapto
Jurnal Geofisika Eksplorasi Vol 4, No 1 (2018)
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ABSTRAK Telah dilakukan penelitian di Lapangan Minyak “HUF” daerah Banyuasin, Sumatera Selatan menggunakan data gayaberat dengan tujuan mengetahui struktur patahan berdasarkan analisis SVD dan mengetahui struktur cekungan hidrokarbon berdasarkan model inversi 3D dari anomali Bouguer dan anomali residual. Daerah penelitian memiliki anomali Bouguer antara 13 mGal hingga 33 mGal dengan interval 1 mGal, dimana nilai anomali Bouguer tinggi memiliki rentang nilai 26 mGal hingga 33 mGal yang berada di arah barat. Sedangkan nilai anomali Bouguer rendah memiliki rentang nilai 13 mGal hingga 20 mGal yang berada di arah timur. Untuk mengetahui keberadaan struktur patahan, dilakukan filtering Second Vertical Derivative (SVD) pada peta Anomali Bouguer, Regional dan Residual. Pola struktur patahan ditunjukkan dengan kontur bernilai nol dan diapit kontur tinggi dan rendah. Dari hasil analisis SVD anomali Bouguer lengkap dan SVD Anomali Residual terdapat 4 (empat) patahan, sedangkan dari SVD Anomali Regional terdapat 3 (empat) patahan. Pemodelan inversi 3D Anomali Residual dilakukan untuk membuktikan keberadaan patahan yang dianalisis berdasarkan hasil analisis SVD dan untuk mengetahui struktur cekungan hidrokarbon. Berdasarkan hasil inversi 3D anomali residual didapatkan cekungan berada pada kedalaman 1500 m – 3300 m dengan nilai densitas berkisar antara 2.24 gram/cc sampai 2.32 gram/cc yang diidentifikasikan merupakan cekungan batu pasir.   ABSTRACT  Oil field research in regional Banyuasin “HUF” , South Sumatra have been done by the gravity data with objective of knowing fault structure based on analysis of hydrocarbon SVD and knows hollow structure based on the 3D model of the Bouguer Anomaly and Residual Anomaly. Study areas had Bouguer Anomaly between 13 mgal up to 33 mgal to the interval 1 mgal, where the value of Bouguer Anomaly high have a range value 26 mgal up to 33 mgal which is in the direction of west. While the low value of Bouguer Anomaly have a range value 13 mgal to 20 mgal that is in the east. To knew  the existence of structure fault, filtering Second Vertical Derivative (SVD) on a Bouguer Anomaly, Regional and Residua mapl.Pattern of structure fault indicated the contours of a zero value and between the high and low contours. From the results of the analysis SVD Complete Bouguer Anomaly and SVD Residual Anomaly there were 4 (four) fault, while from SVD Regional Anomaly there are 3 (three) fault. 3D modeling the Residual Anomaly were conducted to prove the existence of the fault SVD analyzed based on the results of the analysis and to know the hydrocarbon basin. Based on the results of the inversion of 3D the Residual Anomaly, basin was found in the depth of 1500 m – 3000 m with a value of the density ranges from 2.24 gram/cc until 2.32 gram/cc which identified as sandstone basin. Keywords— basin, gravity , hydrocarbon 3D inverse modelling SVD
2D Groundwater Depth for Analysis of The Zone Unconfined Aquifer Juandi, M; Sarkowi, Muh
INSIST Vol 1, No 1 (2016)
Publisher : Universitas Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23960/ins.v1i1.10

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Abstract—Changes in land use have occurred quite significant in the city of Pekanbaru. The increasing of building spaces, the decreasing of plantations and forests are continues to grow with the increasing of population and industries. This means, it can cause impact on   groundwater resources. This condition shall continue in effect, along with the population and industrial growth. This means, it can cause impact on   groundwater resources of Pekanbaru City, thus the analysis of groundwater zone of Pekanbaru city is needed. The data used in this research is related with the biophysical and social economic. Data analysis method was using numeric simulation programming using finite difference method. The results showed that in 2016, its depth ranges between 16-46 m, this indicates that the unconfined aquifer was in trapped position but not included to the confined aquifer system. In 2017, it was predicted that the depth is about 6-38 m, and in 2018 the depth of unconfined aquifer will go deeper to 31,4-34 m. This is influenced by the changes of population and industrial and the automation of extraction of groundwater by those population and industrial is getting bigger. While in 2019 and 2020, the depth of the unconfined aquifer will be between 41,8-44,4 m and 44-46,8 m. It was predicted that the growth of population and industries will grow rapidly in the future. This rapid growth will cause the damage of the aquifer.   Keywords—Zone, groundwater, numerical method.
IDENTIFIKASI BATAS SUB-CEKUNGAN HIDROKARBON MENGGUNAKAN ANALISIS SHD (SECOND HORIZONTAL DERIVATIVE) DAN SVD (SECOND VERTICAL DERIVATIVE) BERDASARKAN KORELASI DATA GAYABERAT DAN SEISMIK Andari, Wuri; Sarkowi, Muh; Karyanto, Karyanto; Kurniawan, Riski
Jurnal Geofisika Eksplorasi Vol 5, No 1 (2019)
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Abstrak - Metode gayaberat secara umum dapat membaca perbedaan densitas batuan untuk mengidentifikasi struktur bawah permukaan. Penelitian ini dilakukan di daerah Riau dengan tujuan mengetahui struktur sesar, struktur bawah permukaan dengan pemodelan 2D dan menentukan batas sub-cekungan. Pengolahan data dilakukan dengan menggunakan analisis spektral, analisis SHD dan SVD serta pemodelan 2D yang dikorelasikan dengan penampang seismik untuk mengetahui struktur bawah permukaan daerah penelitian. Hasil penelitian menunjukkan nilai anomali bouguer daerah penelitian memiliki rentang nilai antara 5.6 mGal hingga 33.2 mGal dengan densitas rata-rata permukaan sebesar 1.95 gr/cc. Anomali tinggi berada pada daerah bagian timur dan anomali rendah berada pada daerah berarah NW – SE.  Banyaknya anomali rendah yang mengindikasikan pola sub-cekungan berjumlah 6 yang dipisahkan oleh daerahtinggian yang relatiftegasberarah Tenggara Baratlaut. Kedalaman rata-rata anomali residual berkisar 2.3 km, berdasarkan hasil pemodelan 2Dbawahpermukaan terdapat struktur lapisan dari yang termuda yaitu endapan alluvial, Formasi Petanie, Kelompok Sihapas dan batuan granit sebagai batuan dasarnya. Penampang bawah permukaan yang diproyeksikan ke atas permukaan menunjukan adanya 5 sub-cekungan dengan lebar cekungan antara 4 – 12 km yang terletak di daerahindikasi sub-cekungan dan indikasi sesar daerah penelitian.  Abstract - Gravity method generally can read the difference of rock density to identify subsurface structures. This research was conducted in Riau area with the aim of knowing fault and subsurface structure, and determining sub-basin boundary. Data processing was done by using spectral analysis, SHD and SVD analysis, and 2D modeling then later correlated with seismic section to find out the subsurface structure of research area. The results showed that the bouguer anomaly value had a range of values between 5.6 mGal to 33.2 mGal with a surface density of 1.95 g / cc. High anomaly were in the eastern region and low anomaly were in the NW - SE trending region. 6 low anomalies indicated as a sub-basin pattern were separated by a relatively high altitude area of North West Southeast. The average residual anomaly depth was about 2.3 km. Based on the 2D subsurface modeling results, there was layer structure from the youngest to eldest that were alluvial deposits, Petani Formation, Sihapas group and granitic rock as the base rock. The projected subsurface section to surface showed 5 sub-basins with basin width 4-12 km located in the sub-basin and fault indication area. Keywords— Sub-Basin, SVD, SHD, Gravity, Seismic
Identifikasi Gas Biogenik pada Rekaman Seismik Pantul Dangkal Saluran Tunggal di Daerah Perairan Balikpapan Kalimantan Timur OctariaSurajaya, Tiara; Sarkowi, Muh
Jurnal Teori dan Aplikasi Fisika Vol 2, No 1 (2014): Jurnal Teori dan Aplikasi Fisika
Publisher : Universitas Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23960/jtaf.v2i1.1253

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Penelitian mengenai keberadaan gas biogenik di daerah Perairan Balikpapan Kalimantan Timur bertujuan untuk mencari energi alternatif sebagai pengganti migas. Terjadinya gas biogenik yaitu dari unsur organik marin terutama fitoplangton dan unsur organik darat berupa material darat berupa material tanaman dari dataran tinggi kemudian diendapkan di laut sejalan dengan proses naik turunnya muka laut pada masa glasial. Hasil interpretasi seismik pantul dangkal saluran tunggal di daerah penelitian mengindikasikan, bahwa gas biogenik terdapat pada beberapa lintasan terutama Lintasan L-3 berarah Timur-Barat. Pada daerah penelitian Lintasan L-3 berarah Timur-Barat terdapat 3 – 4 lapisan bawah laut dengan kedalaman berkisar 1,3 meter sampai 10 meter. Dan memiliki kedalaman daerah gas biogenik 8,2 meter.