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Banda Aceh can be categorized as an earthquake-prone city because of the existence of two active segments namely Seulimeum and Aceh. Both segments are considered to provide great potential damage in the future. In this article, we conduct a microtremor survey in the Peukan Bada, sub-part of Banda Aceh city, to learn the vulnerability level and supp...
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... segment stretches from Tangse to Aceh Island (covering Pidie and Banda Aceh regions). Meanwhile, Seulimeum Segment extends from Tangse through Seulawah Area to Sabang (Omang et al., 2017;Muzli et al., 2018;Muksin et al., 2019) as shown in figure 1. Aceh segment can be included as one of the most important faults because it has not produced an earthquake for a long time and potential to generate M > 6 ( Simanjuntak et al., 2017, Ito et al., 2012). ...
Citations
... The intensity was influenced by the subsurface condition from the basin structure in the Aceh Tenggara region [5,6,7,8]. The seismic surface waveform will be trapped in long period and amplified up to 2.0 times greater than the normal recording in the basin area [9,10,11]. On other hand, geomorphological studies show that the highest risk level occurred in the basin with alluvial sediment [12,3]. ...
... Here, we conducted a microtremor study to figure out the subsurface condition and its impact represented by the vulnerability level. Microtremor research has been widely studied through the HVSR method was used to investigate the site characteristics for earthquake mitigation for example, the soil condition after the earthquake [5], the site and soil amplification effect [11], microzonation [9,10] and the shallow sedimentary properties [12]. ...
... Here, two horizontal components are combined with the vertical component with the geometric-mean and the multiple azimuths method. The processing procedure was following the recommendations of [18,9] namely, that if a single HVSR trend is determined, then the lognormal median curve can be calculated using the geometric-mean. Furthermore, a statistical modelling of f0 can be calculated and the multipleazimuth can be used [20,21]. ...
The Aceh Tenggara region is located in an tectonically active region and it can be categorized as the prone-area. Historically, there were many major earthquakes occured the active fault called the Tripa segment that has generated massive damages and losses. The study of the seismic vulnerability around the highly populated city in the Aceh Tenggara region, Kutacane City, as the center of economy and office activities must be conducted to prepare the suitable earthquake mitigation program. The microtremor have been recorded at 25 sites with one km grid interval between all points. The record lengths have 30 minutes duration at each site, and they were measured with the Taurus Seismometer in miniseed format. The data were analyzed by using the HVSRpy in order to obtain the Horizontal to Vertical Spectral Ratio for each site by means of the geometric-mean and the multiple azimuths methods. Both methods provided a similar result at both focuses with dominant frequency of 0.8 Hz at the AT01 site and 4.8 Hz at the AT14 location. The preliminary result shows that the higher dominant frequency were recorded along the southern part of the Kutacane city which is associated with the Alas formation.
... The historical events, such as 1964 Seulimeum M 6.4 (Hurukawa & Biana, 2013), 1996 Kutacane M 6.1 ), 2013Bener Meriah M 6.3 (Gunawan et al., 2018, 2017 Pidie Jaya M 6.5 (Muzli et al., 2018, Simanjuntak et al., 2019Qadariyah et al., 2018, Idris et al., 2019, Pasari et al., 2021. Several studies have been studied to explain the tectonic process in the study area, for example, seismic hazard (Omang et al., 2017, Simanjuntak et al., 2020, detailed structure (Lange et al., 2018), geodetic (Gunawan et al., 2019 and tsunami (Syamsidik et al., 2018). Moreover, an updated study must be continuously conducted to explain the recent seismicity in the spatial and temporal conditions. ...
The condition of stress and recent seismicity in the seismic-prone area can be statistically analyzed with the Gutenberg-Richter relation (Log N = a-bM). We apply this relation to the hypocenter distribution for the period 1970-2020 with M ≥ 4 and depth ≤ 100 km in the northern part of Sumatra. Spatially, The results obtained a-values and b-values that figure a lateral heterogeneity and stress accumulation at the interface zone in the subduction system and the northern segmentation of the Seulimeum fault. In time, both zones illustrate a slow time-to-failure cycle and the seismic gap with high-stress accumulation in the specific clusters with high parameter values. The results of the spatial-temporal analysis illustrate that a low statistical parameter value usually precedes each major earthquake event.
Abstrak: Kondisi stress dan seismisitas terkini di daerah rawan gempa dapat dianalisis secara statistik dengan hubungan Gutenberg-Richter (Log N = a-bM). Kami memakai hubungan ini pada distribusi hiposenter pada periode 1970 - 2020 dengan M ≥ 4 dan kedalaman ≤ 100 km di bagian utara Sumatera. Secara spasial, hasil yang diperoleh yaitu nilai-a dan nilai-b yang menggambarkan heterogenitas lateral dan akumulasi stress pada zona pertemuan di sistem subduksi dan segmentasi utara dari sesar Seulimeum. Secara waktu, kedua wilayah menggambarkan siklus time-to-failure yang lambat dan zona seismic-gap dengan akumulasi stress yang tinggi pada kluster tertentu dengan nilai parameter yang tinggi. Hasil analisis spasial temporal menggambarkan bahwa setiap kejadian gempa besar biasanya didahului dengan nilai parameter statistik yang rendah.
Universitas Syiah Kuala (USK) is planning to develop a new campus (Campus II). The location of the study area is relatively close to the Seulimum fault which historically has generated a devastating earthquake. Therefore, a seismic vulnerability study is important to conduct in use for reference before the development. This study aims to determine the seismic vulnerability index in the Campus II development area of USK in Mesjid Raya District, Aceh Besar Regency using a Horizontal to Vertical Spectral Ratio (HVSR) method. Potential earthquake damage can be studied by analyzing the dominant frequency (f0), amplification (A0), seismic vulnerability (Kg), and Vs 30. The microtremor acquisition was carried out by using a Broadband seismometer with 100 sps at 37 measurement points with a distance of 500 meters for each station. We use the Geopsy software to analyze seismic data by applying Fourier transform and STA/LTA concept to Rayleigh waves and obtain the dominant frequency value. The 1D velocity inversion was derived by Dinver using the Neighborhood Algorithm (NA). The results of the analysis show that the dominant frequency value is higher around the STA17 point, while the amplification value and seismic vulnerability are highest in the north (at STA2 and STA3) and in the south (at STA28, STA29, and STA30). The higher amplification region is associated soft soil identified as alluvium (Qh). On the other hand, the 1D inversion results at a depth of 30 shows Vs values of 661.142 - 1106.31 m/s (at STA3 and STA17) which indicates the presence of bedrock, making it suitable for future development although more detail investigation is required.
Based on the geological condition, the research location on the North Bengkulu - Lebong crossing is on the Sumatra fault zone that extends from south to north, which causes this area to have a morphological shape and topography of hills and hills extreme slopes. This research results in landslide-prone micro zonation based on GSS and PGA values obtained from Horizontal-to-Vertical Spectral Ratio (HVSR) method measurements. The research was conducted by measuring 25 research sites. The results of Peak Ground Acceleration (PGA) values processing at the research site, between 0.14 gal - 0.53 gal. Locations with the potential for landslides, shown in blue (0.14-0.29 gal), are located in several spots of the research site. The distribution of Ground Shear Strain (GSS) at the study site is evenly distributed at a value of 10-4, which indicates that the study site is prone to cracking and ground movement. In the distribution of GSS values, it is suspected that the location in the dark red color (10-3) has the highest potential to experience repeated landslides. Based on the results of the calculation of PGA and GSS values on the North Bengkulu - Lebong crossing, the points of landslide-prone locations can be known so that disaster mitigation can be carried out at these locations to reduce the risk that will occur.
Kebutuhan air di Aceh Besar terus mengalami peningkatan seiring dengan bertambahnya jumlah penduduk. Hal tersebut menjadikan eksplorasi air tanah penting dilakukan dalam rangka konservasi air tanah di wilayah tersebut. Pada penelitian ini dilakukan korelasi litologi dari empat sumur berdasarkan data electrical logging dan cutting untuk mengetahui persebaran lapisan akuifer serta kedalamannya di wilayah Aceh Besar. Data electrical logging memberikan informasi mengenai nilai resistivitas dan data cutting memberikan informasi mengenai sampel litologi dari masing-masing sumur. Data yang diperoleh dari keempat sumur diplotkan dengan software Logplot2003 sebagai validasi nilai resistivitas yang diperoleh dari electrical logging terhadap data cutting. Selanjutnya pengolahan data dilakukan dengan menggunakan software Rockwork16 untuk mengkorelasi litologi pada setiap sumur. Dari hasil pengolahan data diperoleh informasi berupa nilai resistivitas 2 – 172 Ωm dan litologi berupa lempung, lanau, lempung, pasir kasar, pasir lempungan, pasir, serpih, pasir lempung, pasir kasar, pasir sedang, pasir kasar, dan lempung di wilayah Aceh Besar. Melalui informasi tersebut dapat diketahui bahwa lapisan akuifer di wilayah aceh besar terletak pada kedalaman 82 m - 101 m dengan nilai resistivitas 37 – 147 Ωm dan 2 – 57 Ωm dengan masing-masing litologi berupa pasir kasar dan kerikil. Lapisan akuifer ini merupakan lapisan akuifer tertekan dan saling tersebar diantara ke empat sumur.
Geology Krueng Raya, Aceh Besar is formed from thick sediment and hard rock consisting of young alluvium and volcanic rock. The study area is characterized by the Seulimeum fault which is recently very active in generating earthquakes. This study aims to analyze microtremor data to determine the value of the seismic vulnerability index in the Krueng Raya area, Aceh Besar. Data acquisition was carried out at 20 measurement points located across the Mesjid Raya District. The data were analyzed using the Horizontal to Vertical Spectral Ratio (HVSR) method. Based on the dominant frequency value and the amplification value, the seismic vulnerability index value in the Krueng Raya area ranges from 0.20 to 12.92 which is categorized as low to moderate. Areas that have low seismic vulnerability index values are in the villages of Lamreh. Areas with a moderate seismic vulnerability index value are Meunasah Kulam Village, and Paya Kameng Village.
Lembang menjadi salah satu daerah yang memi-liki tingkat bahaya kegempaan yang tinggi karena terletak dekat dengan struktur Sesar Lembang. Sebagai langkah mi-tigasi, dilakukan identifikasi karakteristik tanah lokal dan pemodelan struktur kecepatan gelombang geser di wilayah ini. Hal ini sangat penting untuk identifikasi daerah-daerah dengan potensi kerentanan bahaya gempabumi yang ting-gi berdasarkan efek tanah lokalnya, serta untuk perencana-an dan pengembangan infrastruktur bangunan tahan gem-pa. Investigasi ini dilakukan menggunakan metode HVSR dan pemodelan inversi eliptisitas gelombang Rayleigh. Data yang digunakan pada metode-metode tersebut adalah data mikrotremor. Data mikrotremor dikumpulkan dengan me-nempatkan seismograf portabel di 26 titik lokasi pengukuran selama 30 menit untuk masing-masing titik. Hasil dari ana-lisis HVSR menunjukkan bahwa secara umum bagian utara daerah penelitian memiliki nilai indeks kerentanan seismik yang lebih tinggi daripada bagian selatan. Pola sebaran in-deks kerentanan seismik ini selaras dengan pola sebaran nilai amplifikasi yang tinggi dan frekuensi dominan tanah yang rendah di bagian utara daerah penelitian. Pemodelan inver-si eliptisitas gelombang Rayleigh menggunakan kurva ke-luaran HVSR menghasilkan struktur kecepatan gelombang geser hingga kedalaman 30 meter di masing-masing titik. Secara umum, kecepatan gelombang geser yang berkisar an-tara 118-560 m/s meningkat seiring dengan bertambahnya kedalaman. Kecepatan gelombang geser rata-rata hingga ke-dalaman 30 meter (Vs30) ini dapat dijadikan sebagai acuan untuk menilai klasifikasi jenis tanah di lokasi pengukuran. Berdasarkan data yang diperoleh, jenis tanah di seluruh ti-tik pengukuran termasuk dalam jenis tanah sedang dengan rentang nilai Vs30 antara 194.48 m/s-246.23 m/s.
