A passive seismic experiment with 42 short-period stations was setup for 10months from May 2011 within a 20–30km radius covering the Tarutung basin and the northern part of the Sarulla graben along the seismically active Sumatran fault (North Sumatra, Indonesia). The objective of the project is to investigate the geothermal setting based on the Vp and Vp/Vs structures and the distribution of seismicity. We recorded 2856 local earthquakes by at least 8 stations which were reduced to 809 events having gap angle less than 180°. The initial earthquake locations were determined using simultaneous inversion for hypocenters and 1D velocity structure followed by 3D tomographic inversion. The resulting seismicity distribution, Vp and Vp/Vs structure reveal systematic differences between the Tarutung basin and the Sarulla graben. The Tarutung pull-apart basin is characterized by a complex structure reflected by a broader distribution of seismicity compared with the very narrow, rather vertical hypocenter distribution in the Sarulla graben, which was formed by fault-perpendicular extension and not by pull-apart tectonics. High Vp/Vs values near to the surface are imaged within the Sarulla graben and northeast of the Tarutung basin. These features are interpreted as fluid bearing sediments with fracturing indicating potentially favorable conditions for geothermal exploitation. The localized fluid flow northeast of Tarutung could be explained by the releasing step-over structure of the pull-apart basin and resulting dilatational stress regime in this part of the basin. Heat sources are assumed to be located at greater depth in association with magmatic activities accompanying the subduction process, and the heat is transported along the Sumatran fault to shallow depth

Biopolymer-based aerogels are open three-dimensional porous materials that are characterized by outstanding properties, such as a low density, high porosity and high surface area, in addition to their biocompatibility and non-cytotoxicity. Here we fabricated pure and binary blended aerogels from cellulose nanofibers (CNFs) and chitosan (CS), using a chemical-free approach that consists of high-pressure homogenization and freeze-drying. The prepared aerogels showed a different porosity and density, depending on the material and mixing ratio. The porosity and density of the aerogels ranged from 99.1 to 90.8% and from 0.0081 to 0.141 g/cm³, respectively. Pure CNFs aerogel had the highest porosity and lightest density, but it showed poor mechanical properties and a high water absorption capacity. Mixing CS with CNFs significantly enhance the mechanical properties and reduce its water uptake. The two investigated ratios of aerogel blends had superior mechanical and thermal properties over the single-material aerogels, in addition to reduced water uptake and 2-log antibacterial activity. This green fabrication and chemical-free approach could have great potential in the preparation of biopolymeric scaffolds for different biomedical applications, such as tissue-engineering scaffolds.

The demand for bioplastic material for industrial applications is increasing. However, moisture absorption and low mechanical strength have limited the use of bioplastic in commercial-scale applications. Macroalgae is no exception to these challenges of bioplastics. In this study, Kappaphycus alvarezii macroalgae were reinforced with lignin nanoparticles. Lignin nanoparticles (LNPs) were used as a filler to reduce the brittleness and hydrophilic nature of macroalgae (matrix). Lignin nanofiller was produced using a green approach from black liquor of soda pulping waste and purified. The physical, mechanical, morphological, structural, thermal, and water barrier properties of LNPs with and without the purification process in macroalgae films were studied. The bioplastic films’ functional properties, such as physical, mechanical, thermal, and water barrier properties, were significantly improved by incorporating purified and unpurified LNPs. However, the purified LNPs have a greater reinforcement effect on the macroalgae than unpurified LNPs. In this study, bioplastic film with 5% purified LNPs presented the optimum enhancement on almost all the functional properties. The enhancement is attributed to high compatibility due to strong interfacial interaction between the nanofiller and matrix. The developed LNPs/macroalgae bioplastic films can provide additional benefits and solutions to various industrial applications, especially packaging material.

On 6 December 2016, an $Mw$ 6.5 earthquake occurred in Pidie Jaya, Aceh, about 30 km to the north of the Sumatran fault (SF) that killed more than 100 people and destroyed $∼3000$ buildings. Mainshock focal mechanism inversions using regional Agency for Meteorology, Climatology, and Geophysics of Indonesia (BMKG) broadband data and teleseismic waveform data all indicate a strike‐slip event with a centroid depth of 11–15 km. The observed macrointensity data show that most of the damaged buildings are distributed along the coast, approximately perpendicular to the ruptured fault strike instead of parallel with it. The strong shaking and damage sites are primarily located on the coastal sedimentary soils, highlighting the importance of site conditions in determining risk. We used one‐month data recorded by nine temporal broadband stations to locate aftershocks with grid‐search and double‐difference algorithms, thereby resolving a linear trend of seismicity aligned in a northeast–southwest direction. The refined aftershock locations indicate a left‐lateral rupture that is in agreement with the preliminary finite‐fault slip inversion as well as geomorphic signatures of local geological structure. Using a well‐located $ML$ 4.2 aftershock for path calibration, we relocated the mainshock epicenter with regional P‐wave arrivals. The refined epicenter falls within the cloud of the well‐located aftershocks, whereas locations from the global and regional catalogs are located 10–20 km away. Aftershock focal mechanisms determined by the first motion reveal similar solutions as the mainshock. This earthquake sequence ruptured a previously unidentified fault that is either located at the west of the fault that produced the 1967 $Mw$ 6.1 earthquake sequence or is actually at the same fault. The Pidie Jaya earthquake and other off‐SF events suggest strong distributed crustal deformation in Aceh, highlighting the need for better understanding of active faulting and seismic hazard in this region.