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All Journal IJOG : Indonesian Journal on Geoscience Journal of Mathematical and Fundamental Sciences Journal of Engineering and Technological Sciences JURNAL METEOROLOGI DAN GEOFISIKA Jurnal Geofisika Indonesian Journal on Geoscience Indonesian Journal on Geoscience PROSIDING SEMINAR NASIONAL FISIKA (E-JOURNAL) Jurnal Meteorologi dan Geofisika
Andri Dian Nugraha
Global Geophysical Group, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung,
Astronomy Chemistry Earth & Planetary Sciences Electrical & Electronics Engineering Energy Engineering Mathematics Physics Other

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Journal : Jurnal Geofisika

 1 
Comparison of 3-D Raytracing and Finite Frequency Tomography Sandy K Suhardja; Yosua Hotmaruli Lumban Gaol; Agus Abdullah; Andri Dian Nugraha; Z. Zulfakriza
Jurnal Geofisika Vol 17 No 1 (2019): Jurnal Geofisika
Publisher : Himpunan Ahli Geofisika Indonesia (HAGI)

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (5587.934 KB) | DOI: 10.36435/jgf.v17i1.393

Abstract

We performed 3-D seismic tomography using teleseismic arrival time at Southwest Mexico. The Mexican subduction zone results from successive fragmentation events that affected the ancient Farallon plate as various segments of the East Pacific rise approached the paleo-trench off western North America. The complexity in this region is related to two subducting oceanic plates, the Rivera and Cocos plates, that have different ages, compositions, convergence velocities and subduction dip angles. In this study, we compared the 3-D raytracing tomography model with finite frequency tomography model. Final models show the differences in amplitude and pattern between the raytracing and finite frequency. 3D raytracing models produced sharper images of fast velocity structures in the mantle. The deeper slabs are more coherent and show less broadening with depth than using 1D finite frequency kernels. However, although the finite frequency and 3-D ray tracing models show some differences in amplitude and pattern, the overall agreement of the models supports the interpretation of Yang et al. (2009) that slab rollback is occurring in South Western Mexico. One possible different interpretation between the raytracing and finite frequency theory results concerns the deep structure of the Rivera slab. The finite frequency models show that the Rivera slab is clearly observable at a depth of about 300km but fades away at greater depths. However, the 3-D ray tracing model shows a clear fast velocity band down to a depth of 400 km and thus our model does not support a slab tear of the Rivera plate above 400 km depth
Analysis of H/V Ratio Curve to Estimate Seismic Hazard Vulnerability in Lombok Island, West Nusa Tenggara, Indonesia Muhammad Randy Caesario Harsuko; Zulfakriza Z.; Andri Dian Nugraha; Muzli Muzli; David Prambudi Sahara; Nanang T Puspito; Yayan M Husni; Billy S Prabowo; Achmad Fajar Narotama Sarjan
Jurnal Geofisika Vol 18 No 1 (2020): Jurnal Geofisika
Publisher : Himpunan Ahli Geofisika Indonesia (HAGI)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.36435/jgf.v18i1.432

Abstract

In 2018, Lombok Island was hit by a series of destructive earthquakes. According to Indonesian Meteo- rological, Climatological, and Geophysical Agency data, about 1,973 felt earthquakes (M > 3) which shaken Lombok were recorded during August 2018 with three earthquakes with the largest magnitude of 6.9 Mw, 6.8 Mw, and 6.2 Mw. National Board for Disaster Management reported about 555 deaths, 1,833 people injured, and 186,010 houses damaged as a result of Lombok earthquake on August 5th, 2018. A number of seismometers were placed on Lombok Island from August 3rd, 2018 to October 19th, 2018 to monitor the aftershock events. There are 17 stations that record seismicity in Lombok consisting of 10 broadband sensors and 7 short period sensors. In this study, we used the Horizontal-to-Vertical Spectral Ratio (HVSR) method to analyze the risk of earthquake in the Lombok region. The basic concept of this method is to do a comparison between the horizontal component spectrum and the vertical component spectrum of a wave, where theoretically the particle movement of the horizontal component is greater than the particle movement of the vertical component on soft ground, whereas on the hard ground both components (horizontal and vertical) will be similar. H/V curve obtained from earthquake record- ings (Earthquake Horizontal-to-Vertical Ratio/EHVR) and H/V curve obtained from microtremor recordings (Microtremor Horizontal-to-Vertical Ratio/MHVR) shows good agreement and high correlation. Empirical correction of EMR (Earthquake-to-Microtremor Ratio) managed to decrease the difference of estimation of predominant frequency and amplification factor between EHVR and MHVR. Predominant frequency, amplification, and seismic vulnerability map agree with the geological condition of Lombok Island, where high value of amplification and seismic vulnerability was found on soft and thick ground. This study conclude that the maximum ground acceleration and the construction of the building should also considered when one wants to investigate the effect of an earthquake to the damage occurred, beside the site effects.
Co-Authors A. Afnimar Achmad Fajar Narotama Sarjan Ade Surya Putra Agus Abdullah Ahmad Basuki Ahmad Syahputra Ahmad Syahputra Ardjuna, Arii Arii Ardjuna Awali Priyono Awan Gunawan Basuki, Ahmad Billy S Prabowo Daryono Daryono David Prambudi Sahara F. Fatkhan Faiz Muttaqy Gede Suantika Hetty Triastuty Hidayati, Sri Jajat Jatnika Mia Uswatun Hasanah Mochamad Agus Moelyadi Mochamad Apri Mohamad Ridwan Muhammad Rahmat Sule Muhammad Randy Caesario Harsuko Muzli Muzli Nanang T Puspito Nanang T. Puspito Pepen Supendi Rexha Verdhora Ry Ry, Rexha Verdhora Sandy Kurniawan Suhardja Septyana, Tepy Sorja Koesuma Sri Hidayati Sri Widiyantoro Syamsurizal Rizal Tepy Septyana Triastuty, Hetty Wandono Wandono Yayan M Husni Yoichi Fukuda Yosua Hotmaruli Lumban Gaol Z. Zulfakriza