Analysis of the Xiaonanhai lithic assemblage,excavated in 1978

An analysis of the lithic artifacts excavated by the late Mr. Zhimin An in 1978 from the Xiaonanhai (Hsiao-nan-hai) Cave site in Anyang County, Henan Province, is presented, in addition to the materials reported in 1965 from the first excavation. Analysis suggests the poor quality of the raw material (e.g. chert) was a major constraint on lithic production at Xiaonanhai. Highly developed fissures within the locally available chert resulted in lithic artifacts that are small in size. Hard hammer direct percussion was the primary mode of stone knapping. The bipolar technique was commonly used as well, which might have been employed to cope with the small, poor quality raw materials. Secondary retouch is simple and not sophisticated. Limited tool types could be classified; most are probably debitage or discarded blanks. Use-wear analysis indicates that most of the flakes were used to process soft materials. Based on the associated faunal diversity, the environment is characterized as a tropical/subtropical forest. This could be the reason for the expedient nature of lithic production at Xiaonanhai. The Xiaonanhai industry might not be related to the Zhoukoudian Locality 1 stone tool industry as traditionally thought, but instead may represent a specific adaptation to the local environment. In terms of what is currently known about the nature of Paleolithic stone tool technology in China, the unilinear model is no longer relevant to explain the Paleolithic development in North China. In order to better understand the complexity and diversity of human behavior, study of the adaptation and idiosyncrasy of specific lithic industries in terms of cultural ecology and how they reflect variability in time stress and risks is required.     

Aftershocks of the june 20, 1978, Greece earthquake: A multimode faulting sequence

A 10-station portable seismograph network was deployed in northern Greece to study aftershocks of the magnitude (m_b) 6.4 earthquake of June 20, 1978. The main shock occurred (in a graben) about 25 km northeast of the city of Thessaloniki and caused an east-west zone of surface rupturing 14 km long that splayed to 7 km wide at the west end. The hypocenters for 116 aftershocks in the magnitude range from 2.5 to 4.5 were determined. The epicenters for these events cover an area 30 km (east-west) by 18 km (north-south), and focal depths ranges from 4 to 12 km. Most of the aftershocks in the east half of the aftershock zone are north of the surface rupture and north of the graben. Those in the west half are located within the boundaries of the graben. Composite focalmechanism solutions for selected aftershocks indicate reactivation of geologically mapped normal faults in the area. Also, strike-slip and dip-slip faults that splay off the western end of the zone of surface ruptures may have been activated.The epicenters for four large (M 4.8) foreshocks and the main shock were relocated using the method of joint epicenter determination. Collectively, those five epicenters form an arcuate pattern convex southward, that is north of and 5 km distant from the surface rupturing. The 5-km separation, along with a focal depth of 8 km (average aftershock depth) or 16 km (NEIS main-shock depth), implies that the fault plane dips northward 58° or 73°, respectively. A preferred nodal-plane dip of 36° was determined by B.C. Papazachos and his colleagues in 1979 from a focal-mechanism solution for the main shock. If this dip is valid for the causal fault and that fault projects to the zone of surface rupturing, a decrease of dip with depth is required.     

Source geometry and mechanism of 1978 Tabas, Iran, earthquake from well located aftershocks

Aftershocks of the September 16, 1978 Tabas earthquake located from close-in observations made during a four-week fielding of temporary stations have been analyzed for the purpose of delineating detailed source geometry of the 1978 earthquake. Spatial distribution of aftershocks and their composite focal mechanism suggest that the geometry of faulting is far from planar. Aftershocks define two prominent alignment. The southern alignment strikes E-W to WNW-ESE, whereas the northern alignment strikes in a N-S to NNW-SSE direction with an abrupt change of nearly 55–60 degrees near 33.4°N latitude. Both field observations of surface faulting pattern and systematic variation of principal directions of stress axes computed from aftershock focal mechanisms are consistent with the upthrusting and imbrication of a wedge shaped crustal block with the wedge angle of about 120 degrees. Both geological and seismological evidence suggest that the deformed zone is truncated at the southern edge by preexisting E-W fault structures. New observations may provide a partial answer to the unexplained farfield asymmetry of the long period Rayleigh wave radiation pattern recently observed for the mainshock across IDA network.