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All Journal JGE (Jurnal Geofisika Eksplorasi) Journal of Geoscience, Engineering, Environment, and Technology Community Development Journal: Jurnal Pengabdian Masyarakat Jurnal Migasian
Iktri Madrinovella
Geophysical Engineering, Pertamina University
Humanities Chemical Engineering, Chemistry & Bioengineering Chemistry Earth & Planetary Sciences Economics, Econometrics & Finance Education Energy Engineering Environmental Science Health Professions Physics Public Health

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THE DIRECT-INVERSION DECONVOLUTION AND ITS APPLICATION IN SEISMIC DATA Iktri Madrinovella; Waskito Pranowo
Jurnal Geofisika Eksplorasi Vol 8, No 1 (2022)
Publisher : Engineering Faculty Universitas Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23960/jge.v8i1.187

Abstract

Seismic traces are generated by the convolution of reflectivity and seismic wavelet. Due to limited frequency bandwidth, reflectivity can not be resolved easily. Deconvolution is a method to increase the frequency bandwidth and gives seismic data higher resolution, which makes it easier to analyze. Deconvolution is a common method in the seismic data processing. The mathematical definition of deconvolution is an inverse process of convolution, but the computation of deconvolution uses convolution in its process (Wiener deconvolution). We explained a method that is direct from the mathematical definition. We refer to it as direct-inversion deconvolution. The direct-inversion deconvolution process involves the matrix operation between seismic trace and wavelet instead of the deconvolution filter. By applying the direct-inversion deconvolution, the produced (or deconvolved) seismic trace shows a better result with higher resolution, regardless of the wavelet’s phase. Finally, we performed a phase rotation experiment, and the deconvolution result shows no seismic phase alteration. In comparison, we also perform spiking deconvolution in synthetic data experiments. This method is applied to The North Sea Volve Data Village seismic data, and more thin layers are significantly detected. Finally, it turns out that direct-inversion deconvolution gives a higher resolution to seismic data.
Identifikasi Batuan Berdasarkan Data Well Log Menggunakan K-Means Clustering Meredita Susanty; Prinsislamsheeny Brilliantdianty Ebelaristra; Ahmad Fauzan Rahman; Ade Irawan; Ikri Madrinovella; Weny Astuti
Jurnal Migasian Vol 4 No 1 (2020): Jurnal Migasian
Publisher : LPPM Institut Teknologi Petroleum Balongan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.36601/jurnal-migasian.v4i1.96

Abstract

One of the stages in oil and gas exploration is a Petrophysical analysis, which aims to determine the structure of rock layers below the earth's surface. The petrophysical analysis uses physical properties in a well-log to determine the rock type below the surface. Nowadays, the software for conducting petrophysical analysis has utilized a machine-learning approach to predict rock types. Most of the software uses the supervised learning method to classify rock types. This research uses a different approach, unsupervised learning, to group rock types based on various features in a well-log. Using a publicly available well-log in Stafford, United States, and the k-means clustering algorithm, this study groups the data into 3 clusters. The result is compared with manual analysis interpretation and shows an alignment between them. From the result, it shows that the unsupervised learning method effectively predicts limestone, shale, and evaporites in the well. It classifies the dataset into useful clusters, generates useful lithologies, provides useful rock characterization, and less time-consuming.
PELATIHAN TSUNAMI READY DESA CIKAKAK YANG SIAP DAN SIAGA BENCANA Madrinovella, Iktri; Lubis, M. Husni Mubarak; Suhardja, Sandy Kurniawan; Zaky, Dicky Ahmad; Herawati, Ida; Pranowo, Waskito; Widyanti, Sari; Misbahudin, Misbahudin; Vikaliana, Resista; Mulyasari, Farah; Iskandar, Yelita Anggiane
Community Development Journal : Jurnal Pengabdian Masyarakat Vol. 4 No. 6 (2023): Volume 4 Nomor 6 Tahun 2023
Publisher : Universitas Pahlawan Tuanku Tambusai

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31004/cdj.v4i6.23240

Abstract

Desa Cikakak di Sukabumi, Jawa Barat merupakan salah satu wilayah yang rawan gempa bumi dan tsunami. Untuk meminimalisir dampak bencana kepada masyarakat desa, dibutuhkan upaya pelatihan yang disebut IOWave23 agar mereka siap dan siaga jika terjadi kedaruratan. Pelatihan semacam ini perlu dilakukan secara berkala sebagaimana arahan Intergovernmental Oceanographic Commission (IOC), The United Nations Educational, Scientific and Cultural Organization) UNESCO. Terakhir diadakan 3 tahun lalu pada 2020 maka pelatihan harus disegerakan mengingat waktu ideal antar pelatihan adalah 2 tahun. Berkaca dari sejumlah bencana serupa di berbagai wilayah rawan di Indonesia maka kegiatan Pengabdian kepada Masyarakat (PkM) kali ini menjadi sangat penting karena memiliki tujuan utama memberikan pemahaman dan latihan langsung di lapangan terkait hal-hal yang harus dikuasai oleh masyarakat di wilayah rawan jika gempa bumi disertai tsuanmi melanda. Masyarakat terdampak perlu memahami hal-hal yang harus dilakukan saat terjadi bencana begitu juga setelahnya. Kegiatan utama pada PkM ini adalah drilling bencana beserta tindakan kesiapsiagaannya yang melibatkan ahli dan praktisi berpengalaman dari berbagai instansi seperti BMKG dan BPBD daerah. Target yang ingin dicapai dari program pelatihan ini peningkatan pengetahuan masyarakat Desa Cikakak mengenai kebencanaan gempa bumi dan tsunami, dan kesiapsiagaan menghadapinya.
Seismic Vulnerability Analysis Using the Horizontal to Vertical Spectral Ratio (HVSR) Method on the West Palu Bay Coastline Amirudin; Madrinovella, Iktri; Sofian
Journal of Geoscience, Engineering, Environment, and Technology Vol. 8 No. 02-2 (2023): Special Issue from The 1st International Conference on Upstream Energy Techn
Publisher : UIR PRESS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25299/jgeet.2023.8.02-2.13879

Abstract

This research was carried out to make a map of the dominant frequency (f0), amplification factor (A0), seismic susceptibility index (Kg), Vs30, Sediment Layer Thickness (H) and Peak ground acceleration (PGA). Microtremor measurements were carried out with a three-component seismometer of the TDL-303S type as many as 27 measurement points. The data was analyzed by the Horizontal to Vertical Spectral Ratio (HVSR) method. The PGA calculation was carried out using the Kanai equation with a reference to the Palu-Donggala earthquake on September 28, 2018. The results showed that the distribution of the dominant frequency value (f0) ranged from 0.4149 Hz-0.8869 Hz, the soil amplification factor (A0) ranged from 2,199–4,884, the seismic vulnerability index (Kg) ranged from 8.79 s2/cm-41.41 s2/cm, the shear wave velocity to a depth of 30 meters ( Vs30) ranged from Vs30 197.7 m/s-320.2 m/s , the thickness of the sedimentary layer ranges from 260.3 m-291.1 m and the peak ground acceleration (PGA) of Kanai ranges from 137.3 gal – 234.2 gal by using Mw 7.4 earthquakes with an intensity scale (MMI) VI to VII. The coastal area of West Palu bay has an intermediate seismic vulnerability II to a high seismic vulnerability IV so that it will be vulnerable in the event of an earthquake disaster. Areas that have a very high vulnerability index are in the upper western and easternmost regions while those with a lower level tend to have a lower vulnerability index value.
SPATIAL AND TEMPORAL B-VALUE ANALYSIS OF THE YOGYAKARTA REGION USING EARTHQUAKE DATA 1960 – 2024 R, Sari Rahayu; Madrinovella, Iktri
JGE (Jurnal Geofisika Eksplorasi) Vol. 10 No. 3 (2024)
Publisher : Engineering Faculty Universitas Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23960/jge.v10i3.468

Abstract

Yogyakarta is one of the areas in Indonesia with a high risk of earthquakes due to its proximity to the subduction zone of the Indo-Australian Plate and Eurasian Plate and the presence of active fault activity, namely the Opak fault, which generates shallow earthquakes. A total of 13 destructive earthquakes were recorded in Yogyakarta and surrounding areas from 1840 to 2023, with the most destructive earthquake occurring in 2006 in Bantul. A total of 417 earthquakes were felt in the Yogyakarta area between May 2006 and March 2016. The high earthquake activity after the 26 May 2006 earthquake indicates a stress field on the active fault segment that has not been fully released.  This study aims to analyze the seismotectonic parameter b-value spatially and temporally to determine the accumulation of tectonic stress in Yogyakarta. The method used is a frequency-magnitude distribution with Gutenberg-Richter relation and Maximum Likelihood approach. Earthquake data were obtained from ISC and BMKG catalogs, with a total of 205 events. The results show that spatially, the b-value of the Yogyakarta region is generally low with a range of values of 0.35 - 0.75 using a grid of 1.5 x 1.5 km and a radius of 15 km with low values around the Opak fault and Ngalang Fault, meaning that the area still holds a high accumulation of stress energy and has the potential for large earthquakes to occur again in the future. Temporal analysis of the b-value shows a tendency for the b-value to decrease before a large earthquake and increase afterwards, reflecting the accumulation and release of stress in the rock.
Co-Authors Ade Irawan Ahmad Fauzan Rahman Amirudin Dicky Ahmad Zaky Ida Herawati Iskandar, Yelita Anggiane Meredita Susanty Misbahudin Misbahudin Muhammad Lubis Mulyasari, Farah Prinsislamsheeny Brilliantdianty Ebelaristra R, Sari Rahayu Sandy Kurniawan Suhardja Sofian Vikaliana, Resista Waskito Pranowo Weny Astuti Widyanti, Sari