Penentuan Nilai Percepatan Tanah Maksimum Terhadap Mitigasi Gempabumi Kabupaten Pidie Jaya, Provinsi Aceh

Penelitian ini dilakukan di daerah Kabupaten Pidie Jaya, yang secara geografis terletak pada koordinat 4˚54 ’15 .702 ’’ N - 5˚18 ’244 N dan 96˚1 ’13, 656 E - 96˚22 ’1.007 E. Fisiografi regional wilayah penelitian dimasukkan dalam peta geologi Banda Aceh, Lohk Seumawe, Takengon, dengan unit fisiografi Zona Kaki Bukit Barisan. Kondisi geologis daerah penelitian terdiri dari Batuan Pra-Tersier, Tersier, dan Kuarterner. Penelitian ini bertujuan untuk menghitung, menganalisis dan menentukan nilai Puncak Maksimal Percepatan Tanah, sehingga peta percepatan tanah dan peta zona mitigasi bencana gempa bumi dapat diperoleh untuk Kabupaten Pidie Jaya. Berdasarkan hasil pengolahan data gempa bumi di Kabupaten Pidie Jaya pada 7 Desember 2016 penulis menemukan nilai maksimum percepatan tanah puncak dengan menggunakan metode Boore (1997) adalah: 225,7 - 85,8 gal. Sementara itu dengan menggunakan metode Fukusima dan Tanaka (1992), hasilnya adalah: 115,0-115,0 gal. Dengan menggabungkan faktor-faktor litologi data sebagai data pendukung lainnya untuk pembobotan, penulis dapat menghasilkan Peta Zona Mitigasi Bencana Gempa Bumi, dari kategori rendah hingga kategori tinggi untuk kabupaten ini. This research was carried out in the Pidie Jaya Regency area, which geographycally situated at coordinates 4˚54 ‘15.702 ‘’ N - 5˚18 ‘2,244 N and 96˚1 ‘13,656 E - 96˚22 ‘1,007 E. Regional physiography of the study area is included in the geological map of Banda Aceh, Lohk Seumawe, Takengon, with the physiographic unit of the Bukit Barisan Foot Zone. The geological condition of the study area is composed of Pre-Tertiary, Tertiary and Quarternary Rocks. This study aims to calculate, analyze and determine the value of Maximum Peak of Ground Acceleration, so that ground acceleration maps and earthquake disaster mitigation zone maps can be obtained for Pidie Jaya District. Based on the results of the earthquake data processing in Pidie Jaya Regency on December 7, 2016 the author find the maximum value of peak ground acceleration using the Boore method (1997) is: 225,7 - 85,8 gal. Meanwhile by using Fukusima and Tanaka method (1992), the result is: 115,0-115,0 gal. By combining those data lithological factors as other supporting data for weighting, the author could produces an Earthquake Disaster Mitigation Zone Map, from low category untill high category for this district.

Individualization of soil classes by disaggregation of physiographic map polygons

The objective of this work was to disaggregate the polygons of physiographic map units in order to individualize the soil classes in each one, representing them as simple soil map units and generating a more detailed soil map than the original one, making these data more useful for future reference. A physiographic map, on a 1:25,000 scale, of the Tarumãzinho watershed, located in the municipality of Águas Frias, in the state of Santa Catarina, Brazil, was used. For disaggregation, three geomorphometric parameters were applied: slope and landforms, both derived from the digital terrain model; and an elevation map. The boundaries of the physiographic units and the elevation, slope, and landform maps were subjected to cross tabulation to identify the existing combinations between the soil classes of each physiographic unit. Based on these combinations, rules were established to select typical areas of occurrence of each soil type in order to train a decision tree model to predict the occurrence of soil classes. The model was trained using the Weka software and was validated with a set of georeferenced soil profiles. Disaggregation enables the individualization and spatialization of soil classes and is useful in producing detailed soil maps.