Mubarak, MuhammadFajri (2017) Spatio-Temporal Seismisitas Sekitar Kompleks Gunung Arjuno-Welirang, Jawa Timur. Sarjana thesis, Universitas Brawijaya.
Abstract
Potensi panas bumi di Kompleks G. Arjuno-Welirang belum dimanfaatkan secara maksimal. Kegiatan eksplorasi terus dilakukan untuk mengetahui sumber panas bumi. Pada penelitian ini dilakukan survei mikroseismik dengan analisis pergerakan partikel. Tujuannya untuk mengetahui sebaran episenter dan hiposenter gempa bumi mikro yang berubah secara spatio-temporal dan sebaran nilai Peak Ground Acceleration (PGA). Akuisisi data dilakukan di dua lokasi (Tretes dan Cangar) menggunakan seismograf TDL-303S. Dalam penentuan episenter dan hiposenter, dilakukan analisis spektrum frekuensi dari sinyal seismik untuk menentukan rentang nilai frekuensi dominan event. Kemudian, dilakukan band pass filter untuk mendapatkan sinyal asli dari event. Hasil penelitian didapatkan rentang frekuensi gempa bumi mikro berkisar 12-24 Hz. Terdiri atas 34 event tersebar di sekitar Daerah Cangar dengan rentang kedalaman 4-262 meter, serta 6 event di sekitar Kawah Welirang dengan rentang kedalaman 985-2152 meter. Adanya sebaran episenter di sekitar kawah menunjukkan perubahan spatio-temporal dari aktivitas gempa bumi mikro, yang mana pada penelitian sebelumnya hanya memperoleh sebaran event berada di sekitar mata air panas. Sumber event di sekitar kawah diduga sebagai akibat aktivitas vulkanik Kawah Welirang. Nilai PGA dihitung menggunakan metode Kanai. Sebaran nilai PGA di Daerah Cangar berkisar 11,23 gal hingga 21,8 gal. Sedangkan, di Daerah Tretes berkisar 5,93 gal hingga 18,87 gal.. Rentang nilai tersebut menunjukkan tingkat risiko akibat gempa tektonik kurang dari Skala VI MMI.
English Abstract
The potential of geothermal have not been fully utilized in the Arjuno-Welirang volcanic complex. Exploration activities were carried out continuously to determine the source of geothermal. In this study, it had been conducted microseismic survey with particle motion analysis. The goals were to determine the distribution of epicenters and hypocenters of micro earthquake which changed in spatio-temporal and also the distribution of Peak Ground Acceleration (PGA) values. Data acquisition was done in two locations (Tretes and Cangar) by using TDL-303S Seismograph. In determining epicenter and hypocenter, analysis of the frequency spectrum was applied in seismic signals to find out the range of dominant frequency values of event. Then, it was filtered by band-pass filter to get the original signal of event. The research results obtained the frequency range of microearthquake is 12-24 Hz. Consists of 34 events spread around the Cangar area with depth ranges 4-262 meters, and 6 events around the Welirang crater with depth ranges 985-2152 meters. The presence of the distribution of epicenters in the vicinity of the crater shows spatio-temporal changes of micro earthquake activities, where in previous research only obtained the distribution of events around the hot springs. The source of events in vicinity of the crater alleged as a result of volcanic-activity in Welirang crater. PGA value was calculated by using Kanai method. The distribution of PGA values had range from 11.23 gal up to 21.3 gal in Cangar, and 5.93 gal up to18.87 gal in Tretes. It shown that the level of risk due to tectonic earthquake is less than V MMI scale.
| Item Type: | Thesis (Sarjana) |
|---|---|
| Identification Number: | SKR/MIPA/2017/214/051704040 |
| Subjects: | 500 Natural sciences and mathematics > 530 Physics |
| Divisions: | Fakultas Matematika dan Ilmu Pengetahuan Alam > Fisika |
| Depositing User: | Kustati |
| Date Deposited: | 30 May 2017 10:07 |
| Last Modified: | 30 May 2017 10:07 |
| URI: | http://repository.ub.ac.id/id/eprint/155256 |
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