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All Journal JGE (Jurnal Geofisika Eksplorasi) Jurnal Pendidikan, Sains, Geologi, dan Geofisika (GeoScienceEd Journal) Geosfera: Jurnal Penelitian Geografi
Styawan, Yudha
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Agriculture, Biological Sciences & Forestry Chemistry Earth & Planetary Sciences Education Environmental Science Physics Social Sciences

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QuakeSee: Aplikasi Cross-Platform Python Berbasis Web untuk Otomasi dan Aksesibilitas dalam Pengunduhan Data Gempa Terbuka Styawan, Yudha
Jurnal Pendidikan, Sains, Geologi, dan Geofisika (GeoScienceEd Journal) Vol. 6 No. 3 (2025): Agustus
Publisher : Mataram University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29303/goescienceed.v6i3.968

Abstract

QuakeSee merupakan aplikasi lintas platform berbasis Python dengan antarmuka web yang dikembangkan untuk meningkatkan efisiensi dan aksesibilitas dalam proses pengunduhan data gempa terbuka. Aplikasi ini memanfaatkan Obspy dan fitur Routing-Client untuk mengoptimalkan pemilihan penyedia data seismik secara otomatis tanpa memerlukan konfigurasi manual. Permintaan HTTP berulang secara otomatis juga dimanfaatkan untuk jumlah kejadian gempa yang tinggi. Melalui antarmuka web yang interaktif, pengguna dapat memperoleh data kejadian gempa, informasi stasiun, serta rekaman seismogram dengan lebih mudah dan cepat. Hasil pengujian menunjukkan bahwa QuakeSee mampu mempercepat proses pengambilan data dibandingkan dengan metode konvensional, khususnya dalam skenario yang melibatkan permintaan data dari beberapa penyedia sekaligus. Selain itu, distribusi dalam format Python Wheel (.whl) serta ketersediaannya di PyPI memungkinkan instalasi yang lebih sederhana dan fleksibel di berbagai sistem operasi. Dengan kombinasi fitur otomasi, antarmuka berbasis web, dan kompatibilitas lintas platform, QuakeSee menjadi solusi yang efektif dan andal bagi pelajar, peneliti serta praktisi seismologi dalam mengakses dan mengelola data gempa secara lebih efisien.
OPTIMALISASI NILAI-B SEISMIK DI WILAYAH JAWA MELALUI PEMODELAN OK1993 BERBASIS VORONOI Styawan, Yudha
JGE (Jurnal Geofisika Eksplorasi) Vol. 11 No. 2 (2025)
Publisher : Engineering Faculty Universitas Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23960/jge.v11i2.489

Abstract

The spatial variation of b-values in seismically active regions provides critical insight into the stress state and rupture potential of fault systems. This study focuses on the Java region and surrounding subduction zones, where detailed mapping of b-values remains uncertain despite high seismic risk. A Voronoi-based ensemble modelling framework is implemented, incorporating the Ogata-Katsura 1993 (OK1993) formulation and spatial sampling via Sobol sequences to ensure uniform partitioning. Earthquake data from 1995 onward were compiled and harmonized into moment magnitude (Mw) using conversion equations from the Indonesian Earthquake Source and Hazard Map 2017. The OK1993 model enables estimation of b-values optimized via trust-constr and initialized with maximum likelihood estimates. The results reveal that high b-values (b > 1.2) dominate offshore southwest Lampung and south of Bali, whereas low b-values (b < 0.8) appear parts of the Sumatra fault near the Sunda Strait, faults across Java, and thrusts north of Bali and Lombok. Moderate b-values (0.8–1.0) extend along the southern Java trench and may represent partially coupled megathrust segments. Interestingly, the low b-value zones may indicate locked asperities and potential seismic gap segments, especially along southern Java, where large ruptures have not occurred in recent decades. This study demonstrates the utility of spatially adaptive, data-driven approaches in capturing complex tectonic segmentation and supports their integration into future seismic hazard assessments in Indonesia, particularly in Java and its surrounding regions.
SITE EFFECTS IDENTIFICATION USING HVSR METHOD IN CISARUA HOT SPRING AREA, NATAR, SOUTH LAMPUNG Farduwin, Alhada; Nugraha, Purwaditya Nugraha; Styawan, Yudha; Lestari, Eka Yunita Purnama; TR, Dina Puspita Julyanti
JGE (Jurnal Geofisika Eksplorasi) Vol. 11 No. 2 (2025)
Publisher : Engineering Faculty Universitas Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23960/jge.v11i2.494

Abstract

Cisarua, which contains a geothermal hot spring, is an intriguing area to investigate due to its location far from any known heat source or volcanic activity. Using the HVSR technique, this study aims to characterize the local site effects based on key parameters: natural frequency (fo), amplification factor (Ao), and average shear-wave velocity down to 30 meters depth (Vs30). Microtremor measurements were conducted at 25 locations across the Cisarua hot spring area, with an average spacing of 300 meters. Each site was recorded for 40–50 minutes, and the data were processed using Geopsy software to extract the HVSR curves, along with the fo and Ao values. The HVSR curves were then inverted using the Particle Swarm Optimization (PSO) algorithm to derive Vs30 values. The results show that fo values range from 0.6 to 1.1 Hz, and Vs30 values are generally below 175 m/s. These two parameters exhibit minimal spatial variation, indicating the presence of thick, soft, and relatively homogeneous sedimentary layers across most of the study area. The Ao values range from 2 to 5, with values below 3 dominating near the geothermal manifestation zone. The spatial distribution of fo and Ao reveals a northwest–southeast trend, which is strongly correlated with the presence of the Lampung–Panjang Fault that likely controls sediment accumulation and layer thickness in the area. Around point T13, Vs30 drops to 125–150 m/s, suggesting localized softening of the soil due to hydrothermal alteration processes. These findings emphasize the interplay between site effects, regional geological structures, and geothermal activity in shaping the dynamic properties of the subsurface in this area.
Pemodelan 3D Perubahan Coulomb Stress Pasca-Gempa Seram Pada 5 Mei 2024 Dengan Magnitudo 6.1Mw Wahyudi, Riski; Auliya, Laila; Nugraha, Purwaditya; Prasetyo, Nugroho; Styawan, Yudha
Geosfera: Jurnal Penelitian Geografi Vol 4, No 2 (2025): Geosfera : Jurnal Penelitian Geografi
Publisher : Universitas Negeri Gorontalo

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37905/geojpg.v4i2.34961

Abstract

This study aims to analyze Coulomb stress changes following the Mw 6.1 earthquake in Seram on May 5, 2024, in order to identify potential subsequent seismic hazards. The methodology employed numerical modeling using Coulomb 3.4 to calculate stress distribution, which was then visualized through spatial interpolation in both 2D maps and 3D cross-sections. The 2D modeling results reveal zones of significant stress increase that spatially correlate with the locations of major earthquakes in 1993 and 1998. The 3D analysis further indicates stress concentration at shallow to intermediate depths (0–12 km), consistent with the distribution of recorded aftershocks, thereby validating the reliability of the model. Additionally, stress transfer was detected toward surrounding faults, particularly the Seram strike-slip segment and the Bobot fault segment. In conclusion, this research demonstrates that Coulomb stress modeling provides a quantitative framework for assessing post-seismic stress evolution and constitutes a crucial basis for disaster mitigation efforts in the tectonically complex Maluku region.
Co-Authors Auliya, Laila Farduwin, Alhada Lestari, Eka Yunita Purnama Nugraha, Purwaditya Nugraha, Purwaditya Nugraha Prasetyo, Nugroho TR, Dina Puspita Julyanti Wahyudi, Riski