Pemrosesan Sinyal Data Sub-bottom Profiler Substrat Dasar Perairan Selat Lembeh

An accurate mapping of ocean seabed is needed to answer the challenges faced by the marine scientist today. Sub-bottom profiler present as one of the acoustics system which used to describe the sediment layer profile of the ocean bottom, as well as the thickness of the layer and the stratigraphy. The purpose of this research is to describe the 2D profile and to determine the value of the reflection coefficient of the sediment layers in Lembeh Strait, North Sulawesi. The reflection coefficient is necessary to be analyzed related to the seabed sediment grain size and type. The data acquisition carried out using Syqwest Stratabox sub-bottom profiler with the frequency of 10 kHz. FFT signal processing and bandpass filter are applied to relieve noise from main signals as well as to get better results. The results of data processing show that seafloor sediments have a value of the surface reflection coefficients which ranged between 0.1168 until 0.7938 with type iron smooth sand

Engineering Of Acoustic Technology For Underwater Positioning Object

Underwater Positioning System (UPS) is a system to track the existence of the position of an object by utilizing the arrival time of the signal measurement. On land, the system uses an electromagnetic signal called GPS. However, because it cannot penetrate water effectively, an acoustic signal is used as an alternative. The purpose of this research is to engineer the control system of data acquisition and underwater acoustic device to measure arrival time (TOA) and apply equation model for underwater sound source positioning system. the effective frequency resonance of the transducer and the hydrophone is at a frequency of 6 kHz. The acquisition control device is able to measure the TOA signal with an error on a digital channel smaller than an analog channel. The difference between the TOA values measured by oscilloscope and acquisition control system is caused by inaccuracy of threshold estimates at the receiver's peak detector circuit. The position of the sound source coordinates obtained from the equation model shows the highest difference in depth point (z) compared to points (x) and (y), caused by the equation model used is limited to four hydrophone units forming a horizontal baseline

Acoustic Detection and Characterization of Marine Sediment with Shallow Seismic Technology in Rambat Waters, Bangka Belitung

High resolution of marine seismic reflection seismic were used to detect the layers of seafloor sediment and to interpret the seismic data geologically. The objectives of this study weres to detect and to characterize the seafloor sediment in the Rambat area, West Bangka, Bangka Belitung. Acquisition data was held on 10-24 August 2012 located between 105.1°00\u2700" - 105.5°00\u2700 " N and 1.7°00\u2700"-1.9° 00\u2700" W. Several methods used to process the data were geometry processing, band pass filter, predictive deconvolution, and Autocoralation Gain Control (AGC) in order to reduce the multiple noise and to ease the data interpretation. Seismic cross section found in Cross Rambat (CRMBT) line 11 exhibited sedimentation process of the sea floor which rocky substrates. The process was assumed to be occurred due to legal and illegal mining activities for long period of time

Evaluasi Terhadap Pelaksanaan Pembelajaran Inovatif Pada Guru SMA Yang Tersertifikasi Dan Solusinya Dikota Surakarta

The aim of this research is to find to what extent senior highschool teachers has applied innovative teaching after passing the certification examination. In addition, this research has the aim to find out the problems that the teachers have in their application of innovative teaching. Based on the problems, this research proposes some recommendations for the solutions for the problems.Specifically, this research wants to find out whether there are any differences in the application of innovative teaching between the teachers who passed the portofolio ceritification exam and those who passed the exam in the Teacher Profession Education and Training (PLPG). This is a qualitative research with observation, depth-interview, questionnaire used as the instruments to get the data of the research. The objects of the research are certifiedb and non-certified senior highschool teachers of natural science, social science, Indonesian and English of both the private and state schools in SurakartaThe research has obtained the following findings. The certification program has created an impact on both certified and non-certified senior highschool teachers in Surakarta. With their limitations, they tend to implement innovative teaching. There is a difference between certified teachers and non-certified teachers. The former teach better than the later. There is a slight difference between the cerified teachers who passed the portofolio exam and the certified teachers who passed the PLPG exam. The portofolio teachers teach more innovatively than the PLPG teachers.The research has also found that the teachers are facing some problems that discourage them to implement innovative teaching. First, they are forced to prepare the students for the National Exam. Secondly, they have the wrong perception that teaching innovatively means using computers or laptops and this means being expensive. To solve the problems, there should be a continuous supervision and monitoring and evaluation for the teachers.

Bathymetry and shallow seismic imaging of the 2018 flank collapse of Anak Krakatau

The flank failure and collapse of Anak Krakatau on December 22nd, 2018 triggered a destructive tsunami. Whether the prior activity of the volcano led to this collapse, or it was triggered by another means, remains a challenge to understand. This study seeks to investigate the recent volcano submarine mass-landslide deposit and emplacement processes, including the seafloor morphology of the flank collapse and the landslide deposit extent. Bathymetry and sparker seismic data were used during this study. Bathymetry data collected in August, 2019 shows the run-out area and the seafloor landslide deposit morphology. Bathymetry data acquired in May, 2017, is used as the base limit of the collapse to estimate the volume of the flank collapse. Comparisons between seismic data acquired in 2017 and 2019 provide an insight into the landslide emplacement processes, the deposit sequence, and structure below the seafloor. From these results we highlight two areas of the submarine-mass landslide deposit, one proximal to Anak Krakatau island (∼1.6 km) and one distal (∼1.4 km). The resulting analysis suggests that the submarine-mass landslide deposit might be produced by a frontally compressional, faulted, landslide, triggered by the critical stability slope, and due to the recent volcanic activity. Blocky seabed features clearly lie to the southwest of Anak Krakatau, and may represent the collapse blocks of the landslide. The seismic analysis of the data acquired in August, 2019 reveals that the blocky facies extends to ∼1.62 km in the width around Anak Krakatau, and the block thicknesses vary up to 70.4 m. The marine data provides a new insight into the landslide run out and extent, together with the landslide deposit morphology and structure that are not available from satellite imagery or subaerial surveys. We conclude that the landslide run out area southwest of the recent collapse, is ∼7.02 ± 0.21 km2

Submarine landslide megablocks show half of Anak Krakatau island failed on December 22nd, 2018

As demonstrated at Anak Krakatau on December 22nd, 2018, tsunamis generated by volcanic flank collapse are incompletely understood and can be devastating. Here, we present the first high-resolution characterisation of both subaerial and submarine components of the collapse. Combined Synthetic Aperture Radar data and aerial photographs reveal an extensive subaerial failure that bounds pre-event deformation and volcanic products. To the southwest of the volcano, bathymetric and seismic reflection data reveal a blocky landslide deposit (0.214 ± 0.036 km3) emplaced over 1.5 km into the adjacent basin. Our findings are consistent with en-masse lateral collapse with a volume ≥0.175 km3, resolving several ambiguities in previous reconstructions. Post-collapse eruptions produced an additional ~0.3 km3 of tephra, burying the scar and landslide deposit. The event provides a model for lateral collapse scenarios at other arc-volcanic islands showing that rapid island growth can lead to large-scale failure and that even faster rebuilding can obscure pre-existing collapse

Subsiding Sundaland

(IF 5.01 [2018]; Q1)International audienceSundaland is the currently partially drowned continental landmass (the Sunda shelf) that encompasses Borneo, Sumatra, Java, and the Malay Peninsula. The central part of the shelf has been episodically reclaimed from the sea during successive Quaternary glaciations. Combining geomorphological observations with numerical simulations of coral reef growth, we show that the Sunda shelf is subsiding, and that this intermittent regime of transgressions only prevailed over the last 400,000 years BP. Prior to that age, Sundaland was permanently emerged. We relate this event to transient dynamic topography in the Indo-Australian subduction zone. We anticipate that this revised paleogeography could make Sundaland a remarkable example of the interplay between the solid Earth and the soft Earth (hydro-, atmo-, and bio-sphere)

Subsiding Sundaland: REPLY

(IF 5.01 [2018]; Q1)International audienc

The great Sumatra-Andaman earthquakes : imaging the boundary between the ruptures of the great 2004 and 2005 earthquakes

Segmentation along convergent margins controls earthquake magnitude and location, but the physical causes of segment boundaries, and their impact on earthquake rupture dynamics, are still poorly understood. One aspect of the 2004 and 2005 great Sumatra-Andaman earthquakes is their abrupt termination along a common boundary. This has led to speculation on the nature of the boundary, its origin and why it was not breached. For the first time the boundary has been imaged and, with newly acquired marine geophysical data, we demonstrate that a ridge on the subducting Indo-Australian oceanic crust may exert a control on margin segmentation. This suggests a lower plate influence on margin structure, particularly its segmentation. The ridge is masked by the sedimentary cover in the trench. Its most likely trend is NNE-SSW. It is interpreted as a fracture zone on the subducting oceanic plate. A ramp or tear along the eastern flank of the subducting fracture zone beneath Simeulue Island may be considered as an intensification factor in terms of rupture propagation barrier