Analisis Seismisitas dan Energi Gempabumi diKawasan Jalur Sesar OpakOyo Yogyakarta

Nugroho Budi Wibowo, BMKG Stasiun Geofisika Yogyakarta, Indonesia
Juwita N S, , Indonesia

Abstract


Gempabumi yang terjadi di wilayah D.I Yogyakarta terjadi akibat aktifitas sesar yang terdapat dipermukaan, seperti Sesar Opak – Oyo, Sesar Dengkeng dan Sesar yang terdapat di Perbukitan Menoreh serta aktifitas lempeng tektonik yang terdapat di Selatan Pulau Jawa.Aktifitas sesar Opak Oyo dapat tercermin dari distribusi episenter dan energi gempabumi yang terjadi.Penelitian ini bertujuan menganalisis energi gempabumi yang memiliki episenter disekitar Sesar Opak Oyo secara spasial dan temporal.Berdasarkandata gempabumi tahun 2008 – 2016terdapat 66 event gempabumi dengan 11 event terasa.Distribusi episenter tergambar dalam peta seismisitas dan untuk parameter tektonik digunakan metode least square.Peta seismisitas kawasan Sesar Opak Oyo menunjukkan distribusi episenter lebih banyak di sebelah Timur dan Tenggara Jalur Sesar dengan nilai b hasil perhitungan metode least square yaitu 0.4.Secara temporal, terdapat trend peningkatan kejadian dari tahun 2008 hingga 2015 dan penurunan trend kejadian gempabumi dari tahun 2015 hingga 2017. Energi yang dihasilkan dari gempa pada kawasan Sesar Opak Oyo bervariasi dari 1x105.2 – 1x1012 Joule. Sedangkan, energi yang berasosiasi dengan keberadaan Jalur Sesar Opak memiliki nilaiberkisar antara 1x105.2 – 1x109.6 Joule dengan hiposenter 10 -20 Km.Pola sebaran energi memiliki pola yang hampir sama dengan formasi geologi dikawasan tersebut.

 

THE ANALYSIS OF SEISMICITY AND EARTHQUAKE ENERGY IN OPAK-OYA FAULT AREA YOGYAKARTA

Earthquake occurred in the Region of Yogyakarta were caused by fault activities on the surface, such as Opak-Oyo Fault, Dengkeng Fault and faults in the Menoreh Hills and plate tectonic activities in South of Java. Opak-Oyo Fault activity are reflected from epicenter distribution and earthquake energy. This research aimed to analyze the earthquake energy which has epicenter around the Opak-Oyo Fault in spatial and temporal. Based on earthquake catalogue from 2008 – 2016, there were 66 earthquakes with 11 significant events. Epicenter distribution was reflected in seismicity map and for the tectonic parameter least square method was used. Seismicity map of Opak-Oyo Fault area showed that distribution of epicenter in the Eastern and Southeastern of fault line with the calculation result of b value using least square method is 0.4. In temporal, there is an increasing trend of events in 2008-2015 and declining trend of earthquake in 2015-2017. Earthquake energy that released in Opak-Oyo Fault area has varying value about 1×105.2 – 1×1012 joules. Meanwhile, the energy that associated with the existence of Opak Fault Lines has value between 1×105.2 – 1×109.6 joule with hypocenter of 10-20 km. The energy distribution has similar pattern with geological formations in that area.

 

Keyword : Opak-Oyo Fault, epicenter, seismicity, least square, energy.


Keywords


Sesar Opak Oyo, episenter, seismisitas, least square, energi.

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References


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DOI: https://doi.org/10.21831/jsd.v6i2.15544

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Copyright (c) 2017 Nugroho Budi Wibowo, Juwita N S

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Printed ISSN (p-ISSN): 2085-9872
Online ISSN (e-ISSN): 2443-1273

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