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MODEL KECEPATAN GELOMBANG SEISMIK 1 DIMENSI WILAYAH PAPUA Priadi, Ramadhan; Ulfiana, Emi; Ariyanto, Puji
Jurnal Meteorologi Klimatologi dan Geofisika Vol 5 No 1 (2018): Jurnal Meteorologi Klimatologi dan Geofisika
Publisher : Unit Penelitian dan Pengabdian Masyarakat Sekolah Tinggi Meteorologi Klimatologi dan Geofisika

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (642.416 KB) | DOI: 10.36754/jmkg.v5i1.67

Abstract

Hiposenter adalah salah satu parameter penting dari gempa bumi. Persebaran hiposenter salah satunya sering digunakan untuk mitigasi bencana, pun untuk mengetahui karakteristik seismisitas suatu daerah. Tingkat akurasi penentuan hiposenter sangat dipengaruhi oleh model kecepatan gelombang seismik. Setiap wilayah memiliki model kecepatan yang berbeda terkait struktur bawah permukannya juga berbeda. Artinya, sangat diperlukan suatu model kecepatan lokal untuk menunjang tingkat akurasi hiposenter yang lebih baik. Penelitian ini bertujuan untuk menentukan model kecepatan lokal 1 dimensi wilayah Papua, sebagai salah satu wilayah dengan tingkat seismisitas yang sangat aktif. Model kecepatan diperoleh menggunakan metode inversi Coupled Hypocenter-Velocity yang dijalankan menggunakan program Velest 3.3. Data yang digunakan berasal dari katalog gempa BMKG, sebanyak 392 kejadian gempa bumi di Papua pada tahun 2017. Digunakan sebanyak 24 stasiun jaringan BMKG. Model kecepatan inisial yang digunakan adalah model kecepatan 1 dimensi IASP91. Hasil penelitian menunjukkan kecepatan gelombang seismik lebih cepat dari model kecepatan IASP91 pada kedalaman hingga 7 km, lebih lambat hingga kedalaman 20 km, dan lebih cepat hingga kedalaman 171 km. Nilai RMS residual hingga iterasi ke-6 adalah 0.682643 dengan GAP rata-rata sebesar 190.
RISK LEVEL ANALYSIS OF LIGHTNING STRIKE WITH SIMPLE ADDITIVE WEIGHTING METHOD IN GOWA REGION Priadi, Ramadhan; Hududillah, Teuku Hafid
Jurnal Penelitian Fisika dan Aplikasinya (JPFA) Vol 8, No 1 (2018)
Publisher : Universitas Negeri Surabaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26740/jpfa.v8n1.p17-24

Abstract

Gowa regency is one of the areas in the province of South Sulawesi that has a high potential of lightning events. This is influenced by its geographical location which is close to the mountainous area. This research purpose to analyze the risk level of lightning strike hazard in Gowa regency using Simple Additive Weighting (SAW) method. This research uses lightning strike data from lightning detector boltek sensor recorded by LD2000 software. The data used is event data in 2015 with sensor coordinates of 5.218° S and 119.470° E and using a density grid of 0.01o. The results for Gowa district have a total density of 26797 strikes/kilometers with clustered areas are Tinggi Moncong subdistricts and Bungaya subdistricts which each have a density value of 10443 strikes/kilometers and 5197 strikes/kilometers. The results of this study are expected to represent the level of lightning vulnerability as a reference for making adequate grounding system in areas with high lightning activity in Gowa regency.
IDENTIFICATION OF THE LOMBOK EARTHQUAKE SOURCE MECHANISM M_W 6.9 AND M_W 7.0 ON AUGUST 5 AND 9 2018 Priadi, Ramadhan
Jurnal Penelitian Fisika dan Aplikasinya (JPFA) Vol 10, No 1 (2020): Articles in Press
Publisher : Universitas Negeri Surabaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26740/jpfa.v10n1.p%p

Abstract

Significant earthquakes with magnitudes ranging from M 5.8 to 7.0 occurred in Lombok in the period July to August 2018. 2 earthquake events occurred in a row namely  6.9 on August 5, 2018 (11:46:38 UTC) and  7.0 on August 9, 2018 (14:56:28 UTC). This phenomenon is very rare because earthquakes require a relatively long time to accumulate energy before being released. Based on the uniqueness, slip modeling is carried out in the fracture plane to determine the distribution of energy accumulation zones represented by asperity. Modeling is done by teleseismic body wave inversion at low frequencies. Modeling results show that the earthquake asperity zone of  6.9 is 0 km in strike direction and -18 km width in dip direction with a maximum slip of 1.3 m. While the results of earthquake modeling  7.0 the asperity zone is at -36 km in the strike direction and -7 km in the dip direction. The  7.0 earthquake shows the distribution of the dominant slip almost perpendicularly upward. The highest aspiration zone is in the up-dip portion of the earthquake hypocenter. These results indicate the earthquake slip vectors  6.9 pointing to the earthquake fault plane  7.0. Modeling results also indicate that a significant earthquake in Lombok does not have a single asperity, but is distributed in the fault plane. This is thought to be due to the condition of brittle rocks and enlargement that is limited by time and space.
Identification of Source Mechanisms for the August 5 2018 Mw 6.9 and the August 9 2018 Mw7.0 Lombok Earthquakes Priadi, Ramadhan; Perdana, Yusuf Hadi; Wijaya, Angga; Suardi, Iman
Jurnal Penelitian Fisika dan Aplikasinya (JPFA) Vol 10, No 1 (2020)
Publisher : Universitas Negeri Surabaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26740/jpfa.v10n1.p44-55

Abstract

A series of earthquakes with magnitudes ranging from 5.8 to 7.0 occurred in Lombok in the period of July to August 2018. Two events occurred consecutively, the 6.9 on August 5, 2018 (11:46:38 UTC), and the 7.0 on August 9, 2018 (14:56:28 UTC). Those phenomena are rare because earthquakes usually require a relatively long time to accumulate their energies before being released. Because of those events, so an explanation is needed to explain what happened at the source. In this context, this study aims to determine the relations between the events based on the asperity zone and the slip distributions. Modeling was performed using teleseismic data and seismic inversion of body waves at low frequencies. The result shows that the asperity zone of 6.9 is at 0 km in a strike-direction and -18 km wide in a dip-direction with a maximum slip of 1.3 m, whereas, for the 7.0 event, the asperity zone is at -36 km in the direction of the strike and -7 km in the direction of the dip. Both events have the asperity in the up-dip section with an upward slip distribution towards the up-dip. The slip distribution of the first event and the second one has a relationship because the 6.9 earthquake slip leads to the 7.0 earthquake fault plane. The relation is suspected to be due to the weakening of rock conditions and an enlargement that is limited by space and time during the earthquake. As a result, those two earthquakes are closely related to stress distribution, forming a new asperity zone.