MIKROZONASI SEISMIK DI KAWASAN ITSNU PEKALONGAN DENGAN MENGGUNAKAN METODE HVSR - Abdul Hakim Prima Yuniarto (Unib Press, 2023)
ABSTRAK Aktivitas seismik di wilayah Kabupaten Pekalongan dipengaruhi oleh keberadaan segmen sesar Baribis-Kendeng. Baribis-Kendeng merupakan sesar aktif yang memanjang dari barat ke timur di bagian utara pulau Jawa, sesar tersebut menyebabkan beberapa kerusakan yang diakibatkan oleh terjadinya gempa bumi. Penelitian tentang kerawanan terhadap bencana gempa bumi di kawasan ITSNU Pekalongan perlu dilakukan karena kawasan tersebut terdiri atas 3 buah bangunan bertingkat dan merupakan kawasan yang setiap hari digunakan untuk aktivitas banyak orang. Penelitian dilakukan dengan pengukuran pada 10 titik yang tersebar di kawasan ITSNU Pekalongan. Analisis frekuensi natural dan amplifikasi diolah menggunakan metode HVSR (Horizontal to Vertical Spectral Ratio), sehingga dihasilkan nilai indeks kerentanan seismik dan ketebalan lapisan lapuk di daerah penelitian. Berdasarkan hasil penelitian, pada kawasan ITSNU Pekalongan mempunyai nilai frekuensi natural sebesar 1,99 - 2,27 Hz. Nilai tersebut menunjukkan bahwa kawasan ITSNU Pekalongan termasuk dalam klasifikasi tanah tipe I jenis IV, lapisan tanah tersebut tersusun atas batuan alluvial dengan ketebalan 26 - 29,8 m yang terbentuk akibat proses sedimentasi. Jika terjadi gempa bumi, area yang paling rawan ada di antara gedung aula PCNU Kabupaten Pekalongan dan gedung perkuliahan ITSNU Pekalongan karena mempunyai indeks kerentanan seismik dan amplifikasi tertinggi. Kata kunci: HVSR, Mikrozonasi, Pekalongan ABSTRACT Seismic activity in the Pekalongan Regency area is influenced by the presence of the Baribis-Kendeng fault segment. Baribis-Kendeng is an active fault that extends from west to east in the northern part of Java Island, this fault causes some damage caused by an earthquake. Research on the vulnerability to earthquakes in the ITSNU Pekalongan area needs to be carried out because the area consists of three high-rise buildings and is an area that is used every day for the activities of many people. The research was carried out by measuring 10 points spread across the ITSNU Pekalongan area. Natural frequency analysis and amplification were processed using the HVSR (Horizontal to Vertical Spectral Ratio) method, resulting in seismic vulnerability index values and weathered layer thickness in the study area. Based on the research results, the ITSNU Pekalongan area has a natural frequency value of 1.99–2.27 Hz. This value indicates that the ITSNU Pekalongan area is included in the soil classification of type I and sort IV, the soil layer is composed of alluvial rock with a thickness of 26–29.8 m, which was formed due to the sedimentation process. If an earthquake occurs, the most vulnerable area is between the Pekalongan Regency PCNU hall building and the Pekalongan ITSNU lecture building because it has the highest seismic vulnerability index and amplification. Keywords: HVSR, Microzonation, Pekalongan