THE 9 JULY 551 AD BEIRUT EARTHQUAKE,EASTERN MEDITERRANEAN REGION

Analysis of the Byzantine primary and secondary sources for identifying the historical earthquakes in Syria and Lebanon reveals that a large earthquake (M _s =7.2) occurred in July 9, 551 AD along the Lebanese littoral and was felt over a very large area in the eastern Mediterranean region. It was a shallow-focus earthquake, associated with a regional tsunami along the Lebanese coast, a local landslide near Al-Batron town, and a large fire in Beirut. It caused heavy destruction with great loss of lives to several Lebanese cities, mainly Beirut, with a maximum intensity between IX-X (EMS-92). The proposed epicentre of the event is offshore of Beirut at about 34.00°N, 35.50° E, indicating that the earthquake appears to be the result of movement along the strike-slip left-lateral Roum fault in southern Lebanon.     

A Note on the Extremities of Local Moran's Iis and Their Impact on Global Moran's I

By defining local Moran's I_i as a ratio of quadratic forms and making use of its overall additivity to match global Moran's I, we can identify spatial objects with a strong impact on global Moran's I. First, we concentrate on the spatial properties of local Moran's I_i expressed by the local linkage degree. Depending on whether we use the W- or C-coding of the spatial connectivity matrix, the variance of local Moran's I_i for a small local linkage degree will be either large or small. Note that spatial objects associated with a local Moran's I_i with a large variance affect the global statistic much more than spatial objects associated with a local Moran's I_i with a small variance. Counterintuitively, global Moran's I defined in the W-coding is most influenced by spatial objects with a small number of spatial neighbors. In contrast, spatial objects with a large number of spatial neighbors exert more impact on global Moran's I setup in the C-coding. Second, we investigate the impact of the empirical data on local Moran's I_i and show that local Moran's I_i will only be significant for extreme absolute residuals at and around the reference location. Clusters of average regression residuals cannot be detected by local Moran's I_i. Consequently, spatial cliques of extreme residuals contribute more to significance tests on global autocorrelation.     

IS THERE A NEAR-FIELD FOR SMALL-TO-MODERATE MAGNITUDE EARTHQUAKES?

The major hazard posed by earthquakes is often thought to be due to moderate to large magnitude events. However, there have been many cases where earthquakes of moderate and even small magnitude have caused very significant destruction when they have coincided with population centres. Even though the area of intense ground shaking caused by such events is generally small, the epicentral motions can be severe enough to cause damage even in well-engineered structures. Two issues are addressed here, the first being the identification of the minimum earthquake magnitude likely to cause damage to engineered structures and the limits of the near-field for small-to-moderate magnitude earthquakes. The second issue addressed is whether features of near-field ground motions such as directivity, which can significantly enhance the destructive potential, occur in small-to-moderate magnitude events. The accelerograms from the 1986 San Salvador (El Salvador) earthquake indicate that it may be unconservative to assume that near-field directivity effects only need to be considered for earthquakes of moment magnitude M 6.5 and greater.     

OBTAINING PROBABILISTIC ESTIMATES OF DISPLACEMENT ON A LANDSLIDE DURING FUTURE EARTHQUAKES

The assessment of earthquake triggered landslide hazard may be undertaken using both deterministic and probabilistic techniques. Probabilistic methods have been developed because much of the data can be considered as random variables where parameters such as the angle of internal friction and moisture content do not have a single fixed value but may assume any number of values across a range. This random variability can be modelled by a probability density function (PDF) which describes the relative likeli-hood that a random variable will assume a particular value. Instead of using just the average or expected value of an input parameter, the complete range of possible values can be used to estimate a range of possible outcomes. Thus the probability of a slope being unstable can be obtained rather than a single indicator of stability. Such proba-bilistic analyses allow for the incorporation of the likely variability of each parameter and therefore allow a more intimate assessment of slope stability to be derived. Utilising empirical relationships for calculating earthquake ground motions and associated slope displacement, an investigation was undertaken to identify the contribution that modern simulation techniques could make to the assessment of earthquake-triggered landslides. To achieve this, geotechnical and earthquake data obtained from a deep-seated landslide triggered during the M _w 7.0 Loma Prieta earthquake was used. By incorporating the variability of the geotechnical parameters and the uncertainty in earthquake location the model derived the probabilities associated with increasing amounts of slope displacement during future probable earthquakes. Analysis was undertaken for four of the principal fault segments in the San Francisco Bay area. These estimates were then combined with the occurrence probabilities of the earthquakes to provide temporal estimates of dis-placement for a 30 year period. Results indicated that a M _w 7.0 earthquake located on the Peninsula Segment of the San Andreas fault was most hazardous with a 11% chance of minor slope displacement (≥0.10 m) and a 6% chance of moderate slope displacement (≥0.30 m) within the next 30 years.     

Earthquake‐related temperature changes in two neighboring hot springs at Xiangcheng,China

Pre‐earthquake and postearthquake temperature changes were documented in two hot springs at Xiangcheng. Pre‐earthquake changes were documented in spring I, 13 days before and 106 km away from the M_s 5.8 Zhongdian earthquake. The 11‐year cutoff spring spouted again, and the spouted water was 24°C hotter than the former escaping gas. Postearthquake changes were documented in spring II following the 2008 M_w 7.9 Wenchuan earthquake, approximately 425 km away from the epicenter. Temperature in spring II showed a step‐like increase with a magnitude of 4°C induced by the earthquake. Spring I which is 0.3 m apart from spring II did not show a sudden change following the earthquake. However, temperatures in the two springs were identical after the Wenchuan earthquake. It indicates that the earthquake generated new hydraulic connectivity between springs I and II, and the heat transport between the two springs accounts for the postearthquake temperature changes.     

Seismic Site Response Modeling for Three Missouri River Highway Bridges

Three highway bridges spanning the Missouri River flood plain were selected for evaluation of seismic site response for moderate size earthquakes emanating from the New Madrid Seismic Zone (NMSZ) in the Midwestern United States. The NMSZ is known to be capable spawning earthquakes larger than magnitude (M) 7.0, four of which occurred in a three-month period between 1811 and 1812, and the M_w 6.0 earthquake of October 1895 centered near Charleston, Missouri. This study evaluated the likely impacts of long period motion of these historic earthquakes on three long-span highway bridges using geotechnical data obtained from recent investigations. Our results suggest site amplification between 6× and 9×, depending on the magnitude and epicentral distance. We believe that threshold magnitude for serious foundation failure and damage to these bridges is between M_w 6.5 and 6.6. Above these magnitudes widespread liquefaction is predicted, which would effect the peak horizontal acceleration and spectral accelerations, causing the ground motions to be different than predicted. Increase in amplification of the response spectra also should be expected where the periods are higher than 1.0 sec. Therefore, M_w 6.5+ earthquakes at ranges 210–260 km could be expected to engender resonant frequency problems for multiple span bridges and tall buildings (10 to 25 stories) in channel corridors containing 20 to 46 m of unconsolidated sediment.     

THE PRIORITY OF LARGE CITIES IN ZIPF RANK-SIZE RULE SYSTEMS

The author seeks to establish possible reasons for differences in the rates of growth of towns within urban systems with rank-size regularities. It is shown that a system follows Zipf s law if the growth of population N _i of the towns of the system follows the regularity M(ΔN _i )/N _i ～ (In N _i - c) where M is the mathematical expectation, ΔN _i is an increment of Ni over a short period of time, ～ stands for “directly proportional,” and c is a constant.     

SEISMIC HAZARD ASSESSMENT OF METROPOLITAN TEHRAN,IRAN

This paper presents a probabilistic seismic hazard assessment of Tehran, the capital of Iran. Two maps have been prepared to indicate the earthquake hazard of Tehran and its vicinity in the form of iso-acceleration contour lines. They display the probabilistic estimate of Peak Ground Acceleration (PGA) over bedrock for the return periods of 475 and 950 years. Tehran is a densely populated metropolitan in which more than 10 million people live. Many destructive earthquakes happened in Iran in the last centuries. It comes from historical references that at least 6 times, Tehran has been destroyed by catastrophic earthquakes. The oldest one happened in the 4th century BC. A collected catalogue, containing both historical and instrumental events and covering the period from the 4th century BC to 1999 is then used. Seismic sources are modelled and recurrence relationship is established. For this purpose the method proposed by Kijko [2000] was employed considering uncertainty in magnitude and incomplete earthquake catalogue. The calculations were performed using the logic tree method and three weighted attenuation relationships; Ramazi [1999], 0.4, Ambraseys and Bommer [1991], 0.35, and Sarma and Srbulov [1996], 0.25. Seismic hazard assessment is then carried out for 12×11 grid points using SEISRISK III. Finally, two seismic hazard maps of the studied area based on Peak Ground Acceleration (PGA) over bedrock for 10% probability of exceedance in two life cycles of 50 and 100 years are presented. The results showed that the PGA ranges from 0.27(g) to 0.46(g) for a return period of 475 years and from 0.33(g) to 0.55(g) for a return period of 950 years. Since population is very dense in Tehran and vulnerability of buildings is high, the risk of future earthquakes will be very significant.     

The timescale and mechanisms of fault sealing and water‐rock interaction after an earthquake

Hydrogeochemical monitoring of a basalt‐hosted aquifer, which contains Ice Age meteoric water and is situated at 1220 m below sea level in the Tjörnes Fracture Zone, northern Iceland, has been ongoing since July 2002. Based on hydrogeochemical changes following an earthquake of magnitude (M_w) 5.8 on 16 September 2002, we constrained the timescales of post‐seismic fault sealing and water–rock interaction. We interpret that the earthquake ruptured a hydrological barrier, permitting a rapid influx of chemically and isotopically distinct Ice Age meteoric water from a second aquifer. During the two subsequent years, we monitored a chemical and isotopic recovery towards pre‐earthquake aquifer compositions, which we interpret to have been mainly facilitated by fault‐sealing processes. This recovery was interrupted in November 2004 by a second rupturing event, which was probably induced by two minor earthquakes and which reopened the pathway to the second aquifer. We conclude that the timescale of fault sealing was approximately 2 years and that the approach to isotopic equilibrium (from global meteoric water line) was approximately 18% after >10⁴ years.     

Quantification of Linked Column Frame Seismic Performance Factors for Use in Seismic Design

Previous research has proposed the Linked Column Frame (LCF) as a lateral load-resisting system capable of providing rapid return to occupancy for buildings impacted by moderate earthquake events and collapse prevention in very large events. The LCF consists of flexible moment frames (MF) and linked columns (LC), which are closely spaced dual columns interconnected with bolted links. The linked columns (LC) are designed to limit seismic forces and provide energy dissipation through yielding of the links, while preventing damage to the moment frame under certain earthquake hazard levels. The proposed design procedure ensures the links of the linked column yield at a significantly lower story drift than the beams of the moment frame, enabling design of this system for two distinct performance states: rapid repair, where only link damage occurs and quick link replacement is possible; and collapse prevention, where both the linked column and moment frame may be damaged.

Here, the seismic performance factors for the LCF system, including the response modification factor, R, the system over-strength factor, Ω₀, and the deflection amplification factor, C_d, are established following the procedures described in FEMA P695 [2009]. These parameters are necessary for inclusion of the system in the building code. This work describes the development of archetype structures, numerical models of the LCF systems, incremental dynamic analyses, and interpretation of the results. From the results, it is recommended that R, Ω₀, and C_d values of 8, 3, and 5.5 be used for seismic design of the LCF system. A height limit of 35 m (115ft) is recommended at this time as taller LCFs are not considered in this study.     

Stress‐induced temperature variations in groundwater of the Monferrato area (north‐western Italy)

Although characterized by low seismicity, the Monferrato area of north‐western Italy was affected by earthquakes, of magnitude M5.1 and M4.8, in 2000 and 2001. At the same time, marked changes were recorded in water temperature and chemistry in several wells within the epicentral area. In May 2004, an automatic network for the continuous monitoring of groundwater was installed in selected wells to study the phenomenon. Here, we report on data collected during a 3‐year period of groundwater monitoring. During the first year, episodes of water heating (by up to 20°C) were observed in one monitored well. The temporal analysis of the seismic activity recorded in the area revealed as almost all seismic events occurred during the period of elevated water temperatures. The similar timing of earthquakes and groundwater‐temperature anomalies suggests that both may be triggered by the same processes acting in the crust.     

FINITE FAULT MODELLING OF NEAR-FIELD ROCK MOTIONS IN THE NEW MADRID SEISMIC ZONE

Due to lack of strong motion records, point-source and finite-fault models have been used to simulate far-field motions at Memphis and St. Louis Cities from earthquake events in the New Madrid Seismic Zone. However, near-field rock motions and their associated uncertainties have never been studied within this zone. The objectives of this study are to develop a simple procedure to account for the uncertainty effect of earthquake source parameters, to analyze the sensitivity of near-field rock motions to input source parameters, and finally, to generate rock motions at two sites located within 11 km from the southwestern segment (strike-fault) and a third site bove the Reelfoot Rift (reverse fault) using a well-validated finite-fault simulation program; FINSIM. An equal-weight logic tree was developed to ensure that the assumed uncertainties are within physical, geological, and seismological constraints. For each site, 100 acceleration time histories with various combinations of parameter uncertainties were respectively simulated for an earthquake of M _w 7.0, 7.5, and 8.0 from each of the two faults. Their average spectral accelerations were in good agreement with those derived from the attenuation relation-ships representative to the Central and Eastern United States. Numerical simulations indicated that spectral accelerations are sensitive to the slip velocity, depth to top of fault, fault strike, slip distribution, and hypocentre location along the strike.     

MODELLING OF THE GROUND MOTION AT RUSSE SITE (NE BULGARIA) DUE TO THE VRANCEA EARTHQUAKES

An approach, capable of synthesising strong ground motion from a basic understanding of fault mechanism and of seismic wave propagation in the Earth, is applied to model the seismic input at a set of 25 sites along a chosen profile at Russe, NE Bulgaria, due to two intermediate-depth Vrancea events (August 30, 1986, M _ω=7.2, and May 30, 1990, M _ω=6.9). Accordingly to our results, once a strong ground motion parameter has been selected to characterise the ground motion, it is necessary to investigate the relationships between its values and the features of the earthquake source, the path to the site and the nature of the site. Therefore, a proper seismic hazard assessment requires an appro-priate parametric study to define the different ground shaking scenarios corresponding to the relevant seismogenic zones affecting the given site. Site response assessment is provided simultaneously in frequency and space domains, and thus the applied procedure differs from the traditional engineering approach that discusses the site as a single point. The applied procedure can be efficiently used to estimate the ground motion for different purposes like microzonation, urban planning, retrofitting or insurance of the built environment.     

ATTENUATION RELATIONSHIP FOR LOW MAGNITUDE EARTHQUAKES USING STANDARD SEISMOMETRIC RECORDS

Northwestern Italian weak-motion data were used to study attenuation characteristics of horizontal peak ground acceleration (PGA) and horizontal peak ground velocity (PGV) from earthquakes of local magnitudes (M _l ) up to 5.1. Data have been provided by the RSNI (Regional seismic network of Northwestern Italy) and RSLG (Regional seismic network of Lunigiana-Garfagnana) waveform database. The database consists of more than 14000 horizontal components recorded in the period 1999-2002 by both broadband and enlarged band seismometers. The accuracy of the procedure used to extract PGA values from the velocity recordings was verified comparing observed and derived PGA values at station STV2, which was equipped with both a temporary K2 Kinemctrtcs accelerometer and Guralp CMG40 broadband sensor. The attenuation of both peak ground acceleration and peak ground velocity was found to be logarithmically distributed with a strong attenuation for low distances (less than 50 km) and low M _l values (<3.0). The resulting equations are:

Log(PGA)=?3.19+0.87M?0.042M ²?1.92 Log(R)+0.249S,

Log(PGA)=?4.23+0.76M?0.018M²?1.56 Log(R)+0.230S,

where PGA is expressed in g, PGV is expressed in m/s, M is local magnitude, R is the hypocentral distance in kilometers and S is a dummy variable assuming values of 0 and 1 for rock and soil respectively. For increasing distance and magnitude, both PGA and PGV values show a linear distribution. The validity range of the obtained attenuation relationships is 0–200 km for distances and M _l up to 4.5. Sensitivity studies performed by analysis of residuals, showed that predicted PGA and PGV values are stable with respect to reasonable variations of the model and distances providing the data. Comparisons with attenuation relationships proposed for Italian region, derived from strong motion records, are also presented.     

Simulation for Ludian (August 3, 2014, MW 6.2) and Nepal (April 25, 2015, MW 7.8) Earthquakes with Improved Stochastic Point Source Method

The Ludian earthquake (M_W 6.2) and Nepal earthquake (M_W 7.8) are parameterized and then simulated using a new improved version of the stochastic point source method based on a proposed equivalent distance (R_EQL) measure. The improved method considers uniform slip distribution along the fault and is validated by comparing the simulated Fourier response spectrum. Simulated ShakeMaps of Ludian and Nepal earthquakes in terms of PGA also indicate that the results of the improved method are in good agreement with finite-fault method with high efficiency.     

Repairs to an injured early Middle Cambrian Trilobite,Elkedra area,Northern Territory

Wang, Y., Shih, C., Szwedo, J. &; Ren, D. iFirst article. New fossil palaeontinids (Hemiptera, Cicadomorpha, Palaeontinidae) from the Middle Jurassic of Daohugou, China. Alcheringa, 1–12. ISSN 0311-5518.

A new genus and species assigned to the extinct family Palaeontinidae, Synapocossus sciacchitanoae Wang, Shih &; Ren, is described from the Middle Jurassic of Daohugou in Inner Mongolia, China. This new genus is established based on well-preserved fossil specimens with body and complete forewings and hind wings. It differs from other described genera by the following characters: small body size, RP and M₁ coalescing for an interval on the forewings and M_3 + 4 without bifurcation on the hind wings. The RP coalescence with M₁ in Synapocossus Wang, Shih &; Ren previously reported only in Turgaiella Becker-Migdisova &; Wootton, seems to be associated with strengthening of the anterior wing margin. The intra-specific and individual variations of Synapocossus and numerous other insect fossils of northeastern China probably indicate long-lasting ecological stresses and a competitive environment in the Middle Jurassic to Early Cretaceous ecosystems.     

THE SEISMICITY OF THE MARMARA SEA AREA 1800–1899

The paper presents an extended summary of the most important earthquakes of the 19th century in the Marmara Sea region in north-west Turkey. We can find no evidence for a significant earthquake occuring during the first half of the 19th century, a period during which the west terminal of the North Anatolian fault system was much more active further west.This variation of activity with time of segments of fault zones, such as the Anatolian, is typical; the smaller the segment considered the longer the sampling period needed for moment rates and hazard estimates to be reliable. We find that the larger and some of the smaller events of the 19th century are clearly associated with known active faults which have generated earlier and later damaging earthquakes.     

THE ASSESSMENT OF TOTAL SEISMIC MOMENT

In this paper we address two problems: (a) the estimation of the total moment release for the calculation of average strain rates and (b) the assessment of the contribution to the total moment of earthquakes smaller than those available in regional or global catalogues. We also examine the bias associated with the different methods currently in use to estimate earthquake recurrence and total rate of seismic moment release, which are important considerations in engineering seismology and tectonics.     

Reconnaissance Report on Geotechnical Engineering Aspect of the 2015 Gorkha,Nepal, Earthquake

An earthquake of moment magnitude M_w 7.8 struck Nepal at 06:11 UTC on April 25, 2015. Field reconnaissance focused on the geotechnical engineering aspect of the earthquake was carried out in the Kathmandu Valley and regions near the epicenter. This paper presents briefly the geology of Nepal, the accelerogram, and results of standard penetration tests at selected sites in the valley. The study shows the failure case histories including landslides, road embankment settlement, bridge foundations and abutment damage, and liquefaction. The paper also highlights the impact of local soil properties and basin and ridge effect on the severity of damage.