On 9 January 2022, two shallow earthquakes occurred in the east arm of Halmahera, Indonesia, with magnitudes of $Mw$ 5.2 and 5.4 felt at III–V modified Mercalli intensity. The existence of the causative fault for the earthquakes was unknown. One possible explanation is that the earthquakes were caused by the activity of an inactive fault striking in the southeast–northwest direction, and possibly linked to the volcanic activities in Halmahera. Thus, further analysis of their characteristics is crucial to identify the previously an inactive fault. In this study, we relocated the associated earthquake hypocenters using the double‐difference method with an updated velocity model, and determined the focal mechanisms by employing full waveform inversion using moment tensor analysis. The focal parameters were used to analyze the static stress changes. The relocated hypocenters show specific hypocenter clusters, aligning in the north–south direction, associated with left‐lateral faulting mechanisms. This north–south alignment differs from the northeast–southwest trend of some other active faults in Halmahera. We propose that the newly found Tobelo fault dips at an angle of around 80° to the west. The seismic stress change from the mainshock and the foreshock of the Tobelo earthquakes corresponds with the distribution of the aftershocks. A detailed analysis of unidentified faults in the high seismicity area is essential to comprehend the tectonic study of Halmahera Island and its seismic hazard assessments.

Earthquake hypocenter relocation is need to be done to get a better earthquake location with high accuracy so tectonic setting, and seismicity analysis can be get and done for further studies. One of some method to relocate earthquake is teleseismic Double-Difference that used 3D velocity model. This research is done by relocating 7042 of 8845 available earthquakes from January 1^st 2009 – June 12^th 2016 in Moluccas Sea. The result are better earthquake depths, showed by no more fixed depth earthquakes and hypocenter distribution shows subduction pattern which is assossiated to Moluccas Sea Plate. Subducting Plate of Moluccas Sea below Sangihe is getting deeper more way it gets north (± 580 km) and sloping to the south (± 280 km) and the subducting Moluccas Sea below Halmahera Arc is 250 km depth on average. Another result is a rollback of Phillipine plate is found that moves along with Moluccas Sea plate which is subducting below Halmahera Arc.

Gempa bumi tektonik 23 Januari 2018 berkekuatan M 6,1 telah mengguncang wilayah Lebak dan sekitarnya. Guncangan gempa bumi ini berdampak berrisiko yang cukup serius. Menjadi perhatian dari peristiwa ini adalah pusat gempa bumnyai berada di laut pada zona sesar Cimandiri sebagai kelanjutan dari zona sesar yang berada di daratan. Penelitian ini berhasil melakukan relokasi episenter dan hiposenter gempa bumi bersumber dari BMKG dari tanggal 23 hingga 28 Januari 2018 sebanyak 62 kejadian gempa bumi, menentukan bidang sesarnya, dan perkiraan transfer tekanan Coulomb gempa bumi utama (mainshock). Relokasi hiposentrum gempa bumi menunjukan adanya lineasi sumber gempa bumi yang mengarah baratdaya-timurlaut dan berasosiasi dengan terusan zona sesar Cimandiri ke arah arah daratan di Teluk Pelabuhan Ratu. Pengolahan HC-plot dapat menentukan bidang sesar sebenarnya pada gempa bumi Lebak yaitu bidang nodal 2 dengan nilai jurus N 41.79° E, kemiringan 81.4°, rake 43.9°. Selain itu analisis perubahan nilai tekanan Coulomb gempa bumi menunjukkan pengaruh gempa bumi utama yang menyebabkan terjadinya gempa bumi susulan di sekitar wilayah sumber.

The geological map shows that the Mount Endut area possesses a geothermal system, which is suggested by the presence of geothermal surface manifestations: the Cikawah and Handeleum hot springs. The existence of a subsurface geological fault structure along the manifestations creates good permeability for the geothermal reservoir. The purpose of this study was to utilize Global Gravity Model plus (GGMplus) gravity satellite data to prove the existence of a geological fault structure around the manifestation area with the first horizontal derivative (FHD) and second vertical derivative (SVD) methods; then, we developed a conceptual model of the geothermal system from the 3D-inversion gravity method. Results show a cap suspected of being clay, with a density of 2.52–2.58 g/cm3 at depth of 0–1250 m. The reservoir layer was suspected to be lava rock with a density of 2.60–2.66 g/cm3 at a depth of 1500–3000 m; also, the heat source layer was suspected to be an igneous intrusion with a density of 2.70–2.72 g/cm3 at depth of 1750–3000 m.

Bali dan Nusa Tenggara memiliki kondisi tektonik yang komplek. Aktivitas seismik umumnya pada wilayah penelitian berasal dari subduksi lempeng Indo-Australia (Busur Sunda), patahan naik busur belakang, dan juga aktivitas vulkanis. Penelitian dilakukan untuk mengetahui seismisitas, pola tektonik dan menghitung sudut penujaman lempeng di wilayah Bali hingga Nusa Tenggara berdasarkan metode relokasi Teleseismic Double-Differencedengan model kecepatan 3D. Data yang digunakan adalah data katalog gempabumi BMKG pada periode pengamatan Januari 2010 – Februari 2017 sebanyak 4201 kejadian gempabumi. Hasil relokasi menunjukkan pola sebaran gempabumi yang didominasi oleh gempa-gempa dangkal di wilayah barat daerah penelitian, dan semakin ke arah timur semakin dalam, yang mengindikasikan bahwa gempa tersebut berasal dari zona subduksi