Zonasi Hazard Gempa Bumi Untuk Wilayah Jakarta

Several damaging earthquakes occured in the last decades in Indonesia have alerted the government to mitigate future damages due to earthquake. One of method to minimize the damages is by performing seismic hazard assessment and risk evaluation as the hazard zonation with respect to ground motion characteristics taking into account sources, local geological and soil conditions. This paper performs a microzonation study for Jakarta. Local site effects are assessed by carrying out ground response analysis performed with the NERA routines. The zonation maps are produced with respect to ground shaking intensity in accordance with the manual proposed by World Institute for Disaster Risk Management

IZGLAĐENI MREŽNI SEIZMIČKI UČINAK PRIMIJENJEN ZA UPORABU ZEMLJIŠTA, STUDIJA SLUČAJA NA OTOKU KALIMANTAN, INDONEZIJA

Smoothed gridded seismicity is an analysis model in seismicity that allows for the obtaining of a rate based on the b-value and the same magnitude range. The data study has been collected and analyzed from a background source gathered by PusGen, referred to as the PusGen catalogue, with approximately 70 thousand data points. Two software programs (i.e. USGS PSHA and OpenQuake) were utilized in this study, and both programs have been proven as reliable in the creation of the 2017 Indonesia Earthquake Hazard Map. The final steps are to compare the acceleration map results with the Kalimantan Island land-use map and to analyze suitability development planning against potential hazards and earthquake risks. The results stated that: (1) acceleration due to the shallow background earthquake for the Kalimantan region, range from 0.00-0.25g (using USGS PSHA) and 0.0-0.4g (using OpenQuake); (2) meanwhile, based on the deep background earthquake source, the maximum accelerations that occur are 0.15g and 0.25g when using USGS PSHA and OpenQuake, respectively; (3) the utilized of land-use for the current and future years is in line with the results of the acceleration simulation. The study recommends to take into account the seismic aspects in new planning of the capital city, mining and residential areas in order to reduce the existing risks.Izglađeni (filtriran) mrežni seizmički učinak temelji se na analizi seizmičnosti, tj. izračunu vrijednosti b i odgovarajuće magnitude. U studiji su prikupljeni i analizirani podatci pozadinskoga izvora, prikupljeni u PusGen katalogu koji obuhvaća približno 70 000 podataka. Korištena su dva programska paketa koja su ranije pouzdano upotrijebljena kod izradbe karte potresnih rizika Indonezije 2017. godine, odnosno njihovi dijelovi nazvani USGS PSHA i OpenQuake. Završni dio računa bila je usporedba karte ubrzanja s kartom uporabe zemljišta na otoku Kalimantan te analiza daljnjega održivog razvoja s obzirom na opasnosti i rizik potresa. Dobiveni su sljedeći rezultati: (1) sila ubrzanja s obzirom plitke potrese u prostoru Kalimantana mijenja se 0 – 0,25 g (prema USGS PSHA), odnosno 0 – 0,4 g (OpenQuake); (2) temeljem dubokih seizmičkih izvora najveće ubrzanje izračunano je u intervalu 0,15 – 0,25 g (USGS PSHA, OpenQuake); (3) uporaba zemljišta, kako danas, tako i u budućnosti, treba pratiti rezultate simulacija (ubrzanja), za koje je preporučeno da postanu dio urbanoga planiranja glavnoga grada regije, ali i okolnih prostora u kojima se rudari

Determination of The Site Amplification on Deep Soil Layer Using 1-D Site Response Analysis (Case study: Jakarta City, Indonesia)

The dynamic response of deep soil layers is used in the development of microzonation maps. The empirical correlation between standard penetratation blow count numbers and S-wave velocity was derived for practical purposes in site characterization based on local data in a case study in Jakarta, Indonesia. For estimating the intensity of potential earthquake shaking at the ground surface as a function of depth to the bedrock surface layer, 1-D site response analysis was carried out in 5745 simulations. The site amplification values were then evaluated by dividing the spectral acceleration (SA) at ground surface by the SA at rock outcrop. Plots of the SA amplification values at interested depth intervals of the bedrock surface layer were assigned. The results showed that the site amplification values estimated by considering the local depth of the bedrock surface layer were generally smaller than the SA amplification values from the Indonesian seismic building code SNI-1726-2012. Also, there appears to exist a tendency of lower levels of mean regression of amplification, in particular for the soft soil site class

Development of Nationwide Vs30 Map and Calibrated Conversion Table for Indonesia using Automated Topographical Classification

A nationwide Vs30 map for Indonesia was developed based on automated topographic classification from 90-m grid digital elevation data and their correlation with Vs30. Automated topographic classification has been proposed by Iwahashi and Pike (2007) and a procedure to convert topographic class into Vs30 maps has been developed by Imamura and Furuta (2015) based on Vs data from J-SHIS (Japan Seismic Hazard Information System). In order to be suitable for Indonesia, calibration work according to Imamura and Furuta's procedure should be conducted since the geotechnical conditions in Japan may not be the same as in Indonesia. This paper presents adjustment of the Vs30 correlation by Imamura and Furuta to convert topographic class into Vs30 and construct a Vs30 map of Indonesia. This correlation was calibrated by using Vs data from BMKG (Indonesian Agency for Meteorological, Climatological, and Geophysics) as well as standard penetration test logs that were collected by the authors. Utilization of local field measurement data will certainly enhance the reliability of the Vs30 map. The developed nationwide Vs30 map will be very useful for disaster mitigation programs and for preliminary design of earthquake resistant buildings and infrastructure in Indonesia

Studi Penurunan Kekuatan Geser Tanah Lempung Indramayu Akibat Pupuk Kimia

Abstrak. Revolusi hijau yang dimulai tahun 1960 dan masuk ke Indonesia tahun 1972, telah dapat menanggulangi ancaman kekurangan pangan global, tapi efek samping dari pelaksanaannya juga bisa dirasakan saat ini yaitu keseimbangan ekosistim alam. Pemberian pupuk kimia yang terus-menerus dan tidak terkontrol telah banyak merubah komposisi tanah sehingga perilaku tanah juga ikut berubah. Untuk itulah penelitian ini dibuat, yaitu mengetahui pengaruh kandungan pupuk kimia dalam tanah terhadap kuat geser tanah. Contoh tanah diambil dari salah satu daerah rawan longsor di Jawa Barat yaitu Indramayu. Jenis tanah adalah lempung dengan kadar halloysite 45,92 montmorillonite 25,34%, specific gravity 2,58, batas cair (LL) 74,26% dan Indeks Plastisitas 46,39%. Contoh tanah yang diuji dibuat dengan kadar air optimum dan jenis pupuk kimia yang digunakan adalah Urea, TSP dan NPK dengan kadar 0,01%, 0,1%, 0,5% dan 1%, serta masa pemeraman 0, 1, 3, 7, dan 14 hari. Pengujian kuat geser tanah yang dipakai adalah kuat tekan bebas (UCS) dan sebagai kontrolnya digunakan triaxial UU. Hasil yang diperoleh dari penelitian ini menunjukkan bahwa dengan adanya kandungan pupuk kimia dalam tanah telah mempengarui plastisitas dan kuat geser tanah. Pengaruh kuat geser tanah yang terjadi akibat pupuk kimia ini adalah semakin banyak kandungan pupuk kimia dalam tanah maka semakin menurun nilai kuat geser tanah tersebut dan penurunan ini bertambah seiring dengan bertambahnya waktu pemeraman. Penurunan nilai kuat tekan bebas (qu) terbesar terjadi pada tanah yang mengandung pupuk TSP, disusul oleh tanah yang mengandung pupuk Urea, kemudian tanah yang mengandung pupuk NPK. Abstract. Green revolution which is started on 1960 and came into Indonesia on 1972, have earned to overcome threat lacking of global food, but side effects of its execution also can be felt in this time that is balance of natural ecosystem. Using of chemical fertilizer continuously without controlled have been changed soil composition so that behavior of the soil also follow to change. To that's this research is made, that is knowing effects of chemical fertilizer content in the soil to shear strength of soil. Samples of soil taken from land one of the gristle slide area in West Java that is Indramayu's clay. Type of soil is clay with rate 45,.92% Halloysite, 25,34% montmorillonite, specific gravity 2,58, liquid limit (LL) 74,26% and Plasticity Index 46,39%. Samples of soil made with optimum water content and chemical fertilizer type used are Urea, TSP and NPK with rate 0,01%, 0,1%, 0,5% and 1%, and period of curing 0, 1, 3, 7 and 14 day. Shear strength test for samples used unconfined compression test (UCS) and UU Triaxial test used as control. Resulting from this research indicate that with existence of chemical fertilizer content in the soil have change plasticity and strength of soil. Shear strength effect of soil that happened from this chemical fertilizer is more chemical fertilizer content in soil more reduce value of shear strength progressively and this degradation increase along with increasing time of curing. Degradation of value of qu biggest happened on soil with TSP, caught up by soil with Urea, then soil with NPK

ANALYSIS AND EVALUATION OF PEAK GROUND ACCELERATION AMPLIFICATION FACTOR ON GROUND SURFACE

Perencanaan infrastruktur tahan gempa, umumnya memerlukan data percepatan di permukaan tanah. Saat ini American Society of Civil Engineers (ASCE) 07-2010 memberikan faktor amplifikasi untuk kebutuhan perencanaan bangunan tahan gempa sehingga perencana bisa mendapatkan percepatan dipermukaan dengan mengalikan nilai percepatan Peta Gempa Indonesia 2010 dengan faktor amplifikasi tersebut. Untuk mengetahui kesesuaian faktor amplifikasi tersebut terhadap analisis seismic hazard menggunakan piranti luak PSHA-07-USGS maka dilakukan kajian dengan analisis grid di Sumatera menggunakan variasi kecepatan gelombang geser (VS) yang mewakili Klasifikasi jenis tanah ASCE 07-10 untuk tanah sangat padat dan batuan luak (SC), tanah sedang (SD) dan tanah lunak (SE). Perbandingan faktor amplifikasi antara hasil analisis dan ASCE 07-2010 terhadap 2 (dua) tinjauan periode (PGA dan 0.2 detik) menunjukkan bahwa utuk site SC  dan SD, hasil analisis menunjukkan hasil yang cukup mendekati ASCE 07-2010. Untuk site SE dan periode T = 1 detik, untuk permodelan dengan VS30 < 175m/detik diperoleh deviasi yang cukup besar antara analisis dan ASCE 07-2010. Hal ini kemungkinkan disebabkan oleh keterbatasan permodelan, yaitu hanya dapat menggunakan persamaan atenuasi tertentu yang hanya mewakili sumber gempa sesar. Untuk mendapatkan faktor amplifikasi yang baik disarankanuntuk melakukan analisis respon dinamik spesifik berdasarkan kondisi tanah lokal yang sesuai dengan klasifikasi ASCE 07-2010.   Kata kunci : Analisis seismic hazard, faktor amplifikasi, percepatan puncak di permukaan, respon spektra di permukaan.Earthquake resistant infrastructure planning, generally require the acceleration data at ground level. Currently, the American Society of Civil (ASCE) 07-2010 provides amplification factor for earthquake resistant building design needs so that planners can get the acceleration of the surface by multiplying the value of the accelaration of Infonsesian Earthquake Maps 2010 with the amplification factor. To evaluate the amplification facttor with the seismic hazard analysis using software USGS PSHA-07, evaluation using grid analysis in Sumatra was done using variations of shear wave velocity(VS) which represents the ASCE 07-10 sites classification for very dense soil and soft rock (SC), the soil medium (SD) and soft soil (SE). According to the amplification factor comparison between analysis result and the ASCE 07-2010 at two reviewed period (PGA and 0.2 sec), the SC and SD  site result show a close amplification factor to ASCE 07-2010. While large deviation occur between analysis and ASCE 07-2010 at SE  site and period T = 1sec with VS30 < 175m/sec. The large deviation probably caused by modeling limitation which only can used specified attenuation function that represent fault zone only. To gain the good quality amplification factor, it is advice to do specific dynamic reponse analysis using local soil condition according to ASCE-07-2010 classification.   Keyword : Seismic hazard analysis, amplification factor, peak surface acceleration, surface spectrum response

Zonasi Hazard Gempa Bumi untuk Wilayah Jakarta

AbstrakBeberapa kejadian bencana gempa bumi yang melanda Indonesia dalam satu dekade ini telah dijadikan isu sangat penting yang mengharuskan pemerintah untuk memitigasi dampak bencana alam tersebut ke depan. Salah satu upaya untuk meminimalkan kerusakan dan kerugian dari bencana gempa bumi dilakukan dengan memetakan hasil pengukuran hazard gempa di suatu kawasan dengan mempertimbangkan karakteristik gempa, pengaruh geologi dan kondisi tanah lokal. Makalah ini mepaparkan studi mikrozonasi di wilayah Jakarta. Analisa respons dinamik tanah dikerjakan dengan program NERA. Hasil studi yaitu peta zonasi hazard gempa bumi berdasar pendekatan yang diadopsi oleh DRM-World Institute for Disaster Risk Management.AbstractSeveral damaging earthquakes occured in the last decades in Indonesia have alerted the government to mitigate future damages due to earthquake. One of method to minimize the damages is by performing seismic hazard assessment and risk evaluation as the hazard zonation with respect to ground motion characteristics taking into account sources, local geological and soil conditions. This paper performs a microzonation study for Jakarta. Local site effects are assessed by carrying out ground response analysis performed with the NERA routines. The zonation maps are produced with respect to ground shaking intensity in accordance with the manual proposed by World Institute for Disaster Risk Management

Development of Spectral Hazard Map for Indonesia with a Return Period of 2500 Years using Probabilistic Method

This study is performed to develop spectral hazard map for Indonesia with a Return Period of 2500 years earthquake. It will be proposed for revision of the Indonesian hazard map in SNI-03-1726-2002 as response to the meeting organized by the Department of Public Works on 27- October-2008 in Jakarta. The meeting has decided to revise the Indonesia hazard map by referring to IBC-2006 where spectral acceleration values at Peak Ground Acceleration/PGA, 0.2 and 1.0 second with a return period of 2500 year will be applied for general buildings. The spectral hazard map was analyzed using total probability method and three dimensional (3-D) source models with recent seismotectonic parameters. Four source models were used in this analysis, namely: shallow background, deep background, fault, and subduction source models. Generally, the results of analysis show the values of PGA with a return period of 2500 years relatively higher 1.2-3.0 times than in SNI-03-1726-2002