No abstract

SUMMARY Detailed source process of the 2000 November 15 Lake Van (eastern Turkey) earthquake (Mw= 5.6) was retrieved using the method of Kikuchi & Kanamori for source inversion of complex body waveforms. The event has been reported by USGS as a deep (67 km) subcrustal earthquake resulting from a rupture on a normal fault beneath the Bitlis Suture zone where continental collision is in action between the Arabian and Eurasian plates. However, our source model based on the analysis of complex body‐waveforms suggests that the earthquake is a shallow crustal event comprised of two subevents on a predominantly reverse fault at depths of 12.5 and 15 km with a time interval of about 18 s. The seismic moment of the second subevent (Mo= 1.6 × 1017 Nm; strike = 76°, dip = 55° and rake = 120°) is larger than the first subevent (Mo= 1.0 × 1017 Nm; strike = 87°, dip = 62° and rake = 110°). Visual inspection of the strong ground motion records and waveform inversion analysis of the near‐field records from four broad‐band stations confirm the occurrence of the two subevents at shallow depths. We examined whether or not the observed complex waveforms of the main shock can be modelled in terms of a single point source embedded at an intermediate depth, and the result turned out to be further evidence for the multiple rupture. The plausibility of the focal depths and mechanisms of the two subevents was also examined by retrieving the source parameters of 14 aftershocks from near‐field waveform data. Most of the aftershocks were relocated at depths around 15 km, which agrees with the shallow main shock. In addition, the analysis of near‐field waveform data indicates subcrustal earthquake activity neither in the source region of the Lake Van earthquake nor in the Turkey–Iran border region. In the Turkey–Iran border region, an event on 1999 February 19 was reported to have taken place at a depth of 66 km (USGS) and 77 km (ISC), which also conflicts with our focal depth (18 km) determined through CMT inversion analysis of the broad‐band records at the station GNI.

In this study, the removal of heavy metals (Cu(II), Ni(II), Zn(II), and total Cr) from real industrial wastewater (IWW), being taken from galvanotechnic industry, by means of polyacrylic acid (Aac) hydrogel was investigated. The effects of adsorbent dosage, contact time, and shaking speed on heavy metal removal from wastewater were monitored using real wastewater. In addition, adsorption isotherm and kinetics studies for adsorption of heavy metals were studied in this study. The adsorption capacities of Aac hydrogel for Cu(II), Ni (II), Zn(II), and total Cr were achieved as 2.74, 1.91, 6.83, and 6.61 mg/g, respectively. The removal of heavy metals using Aac hydrogel was fitted with Freundlich isotherm and pseudo-second-order kinetic models. Thermodynamic studies indicated that the process was exothermic and spontaneous. According to these results, Aac hydrogel is suitable adsorbents for removing heavy metals from IWW.

We have investigated the spatial variation of the stress eld along the fault rupture zone of the 1999 Izmit earthquake (M w 7.4) using rst-motion polarity data at seven distinct aftershock clusters. In our approach, the rst-motion polarities of all the aftershocks in a cluster are simultaneously inverted to determine the stress tensor parameters and fault plane solutions of individual events, in accordance with the method of Horiuchi et al. (1995). Where post-seismic slip was signi cant (e.g., Sapanca, Sakarya-Akyaz , and Karadere segments), we obtained stress tensors with the fault parallel or fault normal maximum (σ 1 ) and minimum (σ 3 ) principal compressive stress axes, which may imply either low frictional coef cients or fault weakness. A stress tensor with similar features was derived from the Ç narc k cluster, where the aftershocks lie in a low-velocity zone beneath the geothermal area. The maximum principal stress axis tends to remain parallel to the trend of the pre-mainshock σ 1 around the Yalova segment; this segment experienced little to no co-seismic displacements. The stress tensor around the Gölcük segment, where the largest surface displacement of 5.5 m was observed, was determined to be 20-25• counterclockwise rotated, but the aftershock alignment remained fault parallel. We interpret these results in terms of the strong crust. On the other hand, both the aftershock alignment and the stress tensor were found to be rotated in the Izmit earthquake epicentral region despite the lower co-seismic displacements. We attribute this feature to the weak crust.

A B S T R A C TIn this study, nanospinels of MnFe 2 O 4 were synthesized by a rapid method of microwaveassisted combustion technique for the removal of total chromium from real industrial wastewater. Nanoparticles of MnFe 2 O 4 were characterized by X-ray diffraction and scanning electron microscopy. The removal of total chromium from real industrial wastewater, which was taken from galvanotechnic industry, using of nanospinel MnFe 2 O 4 was investigated. The effects of adsorbent dosage, contact time, and initial concentrations on total chromium removal from wastewater were studied using the real wastewater. Optimal conditions were found for total chromium removal. Chromium removal and adsorption capacity of MnFe 2 O 4 nanoparticles (NPs) were achieved as 59.35% and 89.18 mg/g, respectively. In addition, other optimum conditions of adsorbent dosage and contact time were found as 1.5 g/L and 120 min in this study, respectively. The removal of total chromium using MnFe 2 O 4 NPs was fitted with Freundlich isotherm and pseudo-second-order kinetic models. The results indicated that MnFe 2 O 4 nanospinels are suitable adsorbents for the removal of total chromium from industrial wastewater.