A back-projection technique allows seismologists to analyse rupture properties once seismic signals from a dense array of seismic networks are available. The observed waveforms are then traced back in space and time to the source region of an earthquake under investigation. In this study, the method utilised the back-projection image of the recorded high-frequency P-seismic waveforms filtered at 0.25-1.0 Hz by Multiple Signal Classification (MUSIC) processing to estimate the extent and the spread of earthquake rupture propagation of the M w 7.5 Palu event on 28 September 2018, generating a severe tsunami. This study aims to estimate rupture duration, its extent (the distance over which rupture propagates) and the corresponding speed, and rupture directivity (where most of the seismic energy propagates). The results revealed that the front of rupture propagates slightly offset southward at about 2.9 km/s over a distance of ~140 km away from the epicentre for about 49 s before slowing down at much smaller amplitudes after reaching the south end of Palu Bay. This finding is consistent with an NNW-SSE orientation of the active Palu-Koro Fault lying along the bay, suggesting that the strong ground motion is associated with the fault activities. This study has therefore substantial implications for enhanced earthquake and tsunami early warnings, helping the government and local authority build community resilience by warning people at risk from future possible earthquake and tsunami hazards.

Data declustering separates mainshocks from both foreshocks and aftershocks while a reliable estimate of completeness magnitude is a key point in seismic parameter determination. These play a role in seismicity-related work. In this preliminary study, we reported seismicity in two Indonesian provinces, namely NTB and NTT, as part of eastern Sunda Arc using the USGS catalogue during 1970-2021 based on performance of three declustering methods (Gardner and Knopoff, Reasenberg, Uhrhammer). These methods were tested along with three techniques of M c determination (MAXC, EMR, BC) provided by ZMAP to estimate minimum magnitude cut-offs, leading to an accurate completeness magnitude. After careful examination, the Reasenberg and BC techniques were proved to be suitable for characterising seismicity in the regions of interest, where M c was calculated under a linear assumption of the cumulative frequency-magnitude distribution (FMD), widely known as the Gutenberg-Richter law. The results revealed that b and a parameters are influenced by the choice of a specific declustering algorithm and calculation of M c. NTT was found to have a higher level of seismicity than NTB and seismicity rates in the southern part of both provinces were higher than those in the northern part. However, the number of strong ground motion with M w ≥ 6.5 in the northern area was larger than that in the southern, indicating the potency of Flores Back-arc Thrust for generating large earthquakes hence possible tsunamis.

Bangil adalah salah satu kecamatan yang ada di Pasuruan sekaligus sebagai ibukota Kabupaten. Secara Geografis, letak Kecamatan Bangil merupakan daerah paling utara di Kabupaten Pasuruan. Pemanfaatan lahan pertanian di bangil tidak hanya digunakan untuk menanam padi, tetapi jenis tanaman dan jenis ikan air tawar bisa menjadi alternatif sebagai pemanfaatan lahan yang ada di wilayah Bangil. Menurut Badan Statistik pada tahun 2021 hasil produksi padi mengalami penurunan sebesar 0,43%. Penurunan produksi pertanian terutama di daerah bangil kelurahan Manarwi terjadi akibat kurangnya pemerataan ketersediaan air dan mengandalkan ketersediaan air di musim hujan saja. Untuk itu agar pemerataan air tercukupi dengan baik, perlu adanya alat alternatif sebagai penyalur ketersediaan kebutuhan air. Pompa air berbasis energi terbarukan bisa menjadi salah satu alternatif untuk mengatasi hal tersebut. Dengan konsep pompa air yang ramah lingkungan, mudah dibuat dan di aplikasikan, tidak membutuhkan bahan bakar atau peralatan elektronik menjadi alternatif baru dan memberikan keuntungan dalam menekan pengeluaran dan tergolong sebagai alat yang murah serta bisa digunakan dalam jangka waktu yang lama. Hal ini mendorong tim PKM untuk memberikan pengarahan dan pembuatan pompa air berbasis free energy kepada masyarakat di wilayah Manarwi. Komponene masyarakat diajak untuk terlibat dalam pembuatan dan pemanfaatan pompa air berbasis free energi ini, meliputi pemerintahan tingakat desa, dan masayarakat di wilayah manarwi. Tahapan pelatihan dan pembuatan Pompa free energy ini meliputi pengetahuan tentang free energy water pump, menjelaskan prinsip kerja free energy water pump, pembuatan free energy water pump, dan menjelaskan serta pengaplikasian free energy water pump dalam bidang pertanian. Keberhasilan pelatihan ini dievaluasi baik pelaksanaannya maupun hasilnya. Evaluasi tersebut dilakukan dengan menggunakan angket respon peserta pelatihan terhadap pelaksanaan kegiatan pelatihan. Hasil angket respon adalah sebagai berikut : terhadap perlunya kegiatan PKM ini sebesar 85%, wawasan system kerja water pump 85%, wawasan tentang prinsip gaya gravitasi pada sistem water pump 82,5%, kegiatan diskusi 80%, pembuatan alat 90%, dan perlunya perkembangan alat 92,5%. The Implementation of Making a Free Energy Water Pump to Improve the Availability of Water Needs on Agricultural Land for the Community of Manarwi Bangil Pasuruan Village Bangil is one of the sub-districts in Pasuruan, which is also the district capital. Geographically, the location of Bangil District is the northernmost area in Pasuruan Regency. The utilization of agricultural land in Bangil is not only used for planting rice, but types of plants and freshwater fish can be an alternative for land use in the Bangil area. According to the Statistics Agency, in 2021, rice production will decrease by 0.43%. The decline in agricultural production, especially in the Bangil area of ??the Manarwi sub-district, occurred due to the lack of equal distribution of water availability and reliance only on water availability in the rainy season.For this reason, so that water distribution is fulfilled correctly, it is necessary to have an alternative tool as a distributor of the availability of water needs. Renewable energy-based water pumps can be an alternative to overcome this. With the concept of a water pump that is environmentally friendly, easy to make and apply, and does not require fuel or electronic equipment, it is a new alternative. It provides the advantage of reducing expenses, is classified as a cheap tool, and can be used for a long time. This prompted the PKM team to give directions and manufacture water pumps based on free energy for the people in the Manarwi area. Community components are invited to be involved in the manufacture and use of this free energy-based water pump, including village-level government and the community in the Manarwi area. The stages of training and making this free energy pump include knowledge, explaining the working principles, making free energy water pumps, and explaining and applying free energy water pumps in agriculture. The success of this training is evaluated both in its implementation and results. The evaluation was carried out using a questionnaire from the training participants' responses to the performance of the training activities. The results of the response questionnaire are as follows: regarding the need for this PKM activity by, 85%, insight into the working system of the water pump 85%, insight into the principle of gravitational force in the water pump system 82.5%, discussion activities 80%, tool making 90%, and the need for tool development 92.5%.

<em><span>Widiyantoro et al., as Institut Teknologi Bandung (ITB) scientists, predict the worst possibility that in the south of Java Island, a megathrust earthquake with a maximum magnitude of up to 9.1 on the Richter scale and a tsunami of up to 20 meters. So understanding and literacy about mitigation of the megathrust earthquake and tsunami need to be improved so that the South Coast of Java Island (Pansela) community has prepared for these disasters. This study aims to analyze the understanding and literacy of the Pansela community of the earthquake and tsunami disaster against the predictions made by ITB scientists. This study uses a qualitative descriptive method with a total of 57 community respondents living in Pansela. The study results show that most communities believe in this prediction and have fewer mitigation efforts against this disaster. However, the respondents still did not know the specifics of the megathrust earthquake. They considered an earthquake in the south of Java Island related to the megathrust earthquake. Therefore, it is necessary to increase community understanding and literacy regarding mitigation efforts against megathrust earthquakes and tsunami.</span></em>