40Ar/39Ar Geochronology of Volcanic and Intrusive Rocks in the Papandayan Metallic Prospect Area,West Java,Indonesia

This study presents new ⁴⁰Ar/³⁹Ar ages on the volcanic and intrusive rocks from the Papandayan metallic district in West Java, Indonesia. The vein system in the Arinem area, one of the prospective areas in the district, has been considered as an epithermal gold–silver–base metal deposit, however, no published age results are available for the host volcanic rocks in the district. The ages of these rocks are critical in terms of their association with mineralization and are important to understand the evolution of volcanism in the region, which has implications for mineral exploration in the district. ⁴⁰Ar/³⁹Ar plateau ages of two typical basalt and one andesite samples of the Jampang Formation volcanic rocks yielded ages of 11.65 ± 0.52 Ma, 18.15 ± 0.46 Ma and 7.69 ± 0.05 Ma, respectively. ⁴⁰Ar/³⁹Ar ages of three intrusive rock samples from Gunung Halang diorite, Gunung Lingga diorite, and Gunung Buligir fine‐grained quartz diorite yielded ages of 12.98 ± 0.20 Ma, 10.81 ± 0.15 Ma, and 7.37 ± 0.05 Ma, respectively. The age of the youngest fine‐grained diorite (Gunung Wayang dike) is 3.95 ± 0.03 Ma. An ⁴⁰Ar/³⁹Ar age obtained from adularia in the Arinem mineralized vein (18.30 ± 0.20 Ma) is older than the age of altered basalt sample of this study (11.65 ± 0.52 Ma) and the K–Ar illite ages of the Arinem vein (9.4 ± 0.3 Ma and 8.8 ± 0.3 Ma) which resulted from a previous study. The age results suggest that the Papandayan district may have experienced multiple hydrothermal and mineralization events. This study, therefore, provides crucial age data to support future mineral exploration in the district.     

Rates of crustal deformation in the North Aegean trough-North Anatolian fault deduced from seismicity

The rates and configuration of seismic deformation in the North Aegean trough-North Anatolian fault are determined from the moment tensor mechanisms of the earthquakes that occurred within this region. The analysis is based onKostrov's (1974) formulation. The fault plane solutions of the earthquakes of the period 1913–1983 withM _s 6.0 are used. The focal mechanism of some of the past events (before 1960) is assumed, based on the present knowledge of the seismotectonics as well as on the macroseismic records of the area studied. The analysis showed that the deformation of the northern Aegean is dominated by EW contraction (at a rate of about 15 mm/yr) which is relieved by NS extension (at a rate of about 9 mm/yr). It was also shown that the northern part of North Anatolia (north of 39.7°N parallel) undergoes contraction in the EW direction (at a rate of about 9 mm/yr) and NS extension as the dominant mode of deformation (at a rate of about 5 mm/yr). It may be stated therefore, that the pattern of deformation of the northern Aegean and the northern part of North Anatolian fault is controlled by the NS extension the Aegean is undergoing as a whole, and the dextral strike-slip motion of the North Anatolian fault. The southern part of North Anatolia is undergoing crustal thinning at a rate of 2.3 mm/yr, NS extension (at a rate of 5 mm/yr) as well as EW extension (at a rate of 4 mm/yr), which are consistent with the occurrence of major normal faulting and justify the separation of North Anatolia into two separate subareas.     

Errors in expected human losses due to incorrect seismic hazard estimates

Seismic hazard maps are constructed by extrapolating from the frequency of small earthquakes, the annual probability of large, infrequent, earthquakes. Combining the potential contribution from all seismically active volumes, one calculates the peak ground acceleration with a probability to be exceeded by 10?% in 50?years at any given point. The consequential risk, the losses to be expected, derives from the damage the calculated shaking causes to buildings, and the impact on occupants due to collapsing structures. We show that the numbers of fatalities in recent disastrous earthquakes were underestimated by the world seismic hazard maps by approximately two to three orders of magnitude. Thus, seismic hazard maps based on the standard method cannot be used to estimate the risk to which the population is exposed due to large earthquakes.     

Imagining ‘home’: Diasporic landscapes of the Greek-German second generation

This article presents research on second-generation Greek-Germans, both those living in diaspora, and those who have ‘returned’ to Greece. The research is multi-sited, with fieldwork in Berlin, Athens, central and northern Greece. After defining and problematising the notions of ‘second generation’ and ‘return’ - especially complex in this context - we focus on the second generation’s diasporic imaginings of ‘home’, particularly their experiences and narrative framings of landscape, space and place. In their narratives, participants ‘remember’ their parents’ narratives about the homeland, and narrate their own experiences of returning to the diasporic hearth. Contrasts are drawn across diverse diasporic landscape imaginings and experiences: between received diasporic memories and ‘pragmatic’ experiences; holiday visits and long-term return; urban, rural and other spaces; and different sites in the diaspora, such as the place of upbringing and the ancestral home.     

A source study of the 6 July 2003 (Mw 5.7) earthquake sequence in the Gulf of Saros (Northern Aegean Sea): Seismological evidence for the western continuation of the Ganos fault

The July 2003 sequence in the Gulf of Saros (Northeastern Aegean Sea) is investigated, in terms of accurate event locations and source properties of the largest events. The distribution of epicenters shows the activation of a 25-km long zone, which extends in depth between 9 and 20 km. The major slip patch of the 6 July 2003 M_w 5.7 mainshock is confined in a small area (45 km²), which coincides with the deeper (12–20 km) part of the activated zone. The epicenters of the sequence follow the northern margin of the Saros depression. This observation supports recent studies, according to which the continuation of the Ganos fault in the Gulf of Saros does not coincide with the fault along the northern coast of the Gelibolu peninsula, but it is located at the northern boundary of the Saros depression. This is further supported by the fact that the focal mechanisms of the mainshock and of the largest aftershocks of the 2003 sequence imply almost pure dextral strike-slip faulting, whereas the fault bounding the Gulf of Saros to the south appears as a normal fault on seismic sections. Thus, we infer that the principle deformation zone consists of a major strike-slip fault, which lies close to the northern margin of the Saros depression and this fault could be regarded as the continuation of the northern branch of the North Anatolian Fault into the Saros Gulf and North Aegean Trough as suggested by regional tectonic models. The northeastern extent of the 2003 sequence marks the western termination (at 26.3° E) of a long-term seismic quiescence observed in the period following the 1912 Ganos earthquake, which may be associated with the extend of the rupture of the particular earthquake.     

Modelling of infiltration using artificial intelligence techniques in semi-arid Iran

ABSTRACT

Infiltration plays a fundamental role in streamflow, groundwater recharge, subsurface flow, and surface and subsurface water quality and quantity. In this study, adaptive neuro-fuzzy inference system (ANFIS), support vector machine (SVM) and random forest (RF) models were used to determine cumulative infiltration and infiltration rate in arid areas in Iran. The input data were sand, clay, silt, density of soil and soil moisture, while the output data were cumulative infiltration and infiltration rate, the latter measured using a double-ring infiltrometer at 16 locations. The results show that SVM with radial basis kernel function better estimated cumulative infiltration (RMSE = 0.2791 cm) compared to the other models. Also, SVM with M4 radial basis kernel function better estimated the infiltration rate (RMSE = 0.0633 cm/h) than the ANFIS and RF models. Thus, SVM was found to be the most suitable model for modelling infiltration in the study area.     

The instability of the <Emphasis Type="Italic">M</Emphasis><Subscript>W</Subscript> and <Emphasis Type="Italic">M</Emphasis><Subscript>L</Subscript> comparison for earthquakes in Greece for the period 1969 to 2007

We use 576 earthquakes of magnitude, M _w, 3.3 to 6.8 that occurred within the region 33° N–42.5° N, 19° E–30° E in the time period 1969 to 2007 to investigate the stability of the relation between moment magnitude, M _w, and local magnitude, M _L, for earthquakes in Greece and the surrounding regions. We compare M _w to M _L as reported in the monthly bulletins of the National Observatory of Athens (NOA) and to M _L as reported in the bulletins of the Seismological Station of the Aristotle University of Thessaloniki. All earthquakes have been analyzed through regional or teleseismic waveform inversion, to obtain M _w, and have measured maximum trace amplitudes on the Wood–Anderson seismograph in Athens, which has been in operation since 1964. We show that the Athens Wood–Anderson seismograph performance has changed through time, affecting the computed by NOA M _L by at least 0.1 magnitude units. Specifically, since the beginning of 1996, its east–west component has been recording systematically much larger amplitudes compared to the north–south component. From the comparison between M _w and M _L reported by Thessaloniki, we also show that the performance of the sensors has changed several times through time, affecting the calculated M _L’s. We propose scaling relations to convert the M _L values reported from the two centers to M _w. The procedures followed here can be applied to other regions as well to examine the stability of magnitude calculations through time.