Soil liquefaction potential induced by the andalusian earthquake of 25 December 1884

On 25 December 1884, an earthquake of epicentral intensityI ₀ = IX in the MSK scale caused great damage in a large area in the provinces of Granada and Málaga, in the south of Spain. The reports of the Spanish, Italian and French Commissions that studied the earthquake described ground phenomena in seven different sites which can be identified as soil liquefaction.By means of dynamic penetration tests carried out in the above sites, the corresponding soil profiles (based on SPT data and water table depth) were established, and the occurrence of liquefaction was proved in five out of seven of these sites. Also, the intensities at such locations and the magnitude of the earthquake were estimated.From the geotechnical data and the cyclic stress ratio induced by the earthquake, liquefaction conditions were confirmed in all the five sites which presumably liquefied. Then, possible values of the minimum ground surface accelerations necessary for the onset of liquefaction at each location were calculated. The results obtained were completed with data reported in six liquefaction case studies from Japan and the United States, from which design charts relating soil acceleration with normalized SPT values for different intensity levels were drawn.Finally, by using standard attenuation curves, the above data were translated into epicentral distances, and good agreement with the known epicentral area was found. As a result, a consistent approach for liquefaction hazard and source location problems has been developed. The proposed method combines in its formulation historical evidence and earthquake engineering techniques.     

Repeated palaeoseismic activity of the Ventas de Zafarraya fault (S Spain) and its relation with the 1884 Andalusian earthquake

One of the most destructive historical earthquakes (M 6.7) in Spain occurred in 1884 along the normal Ventas de Zafarraya Fault located in the Central Betic Cordilleras. Palaeoseismic and radiocarbon data presented in this study are the first to constrain the timing of the pre-1884 fault history in the last 10 ka. These data yield a recurrence interval of between 2 and 3 ka for major earthquakes, under the assumption of uniform return periods along the normal fault. The Holocene slip rate is estimated to be in the order of 0.35±0.05 mm/year, which is significantly higher than the mean slip rate of 0.17±0.03 mm/year since the Tortonian. Several of the most important deformations and secondary features, such as landslides and liquefaction, are related to strong ground motion and document the Holocene activity of the Ventas de Zafarraya Fault.     

The Rukwa earthquake of 13 December 1910 in East Africa

We reappraised the Rukwa earthquake of 1910 in the East African Rift System. With a magnitude of 7.4, no earthquake in East Africa is known to be larger and it is rivalled only by the recent earthquake in southern Sudan on 20 May 1990. More than 80 per cent of the moment release in the Rift during the last 110 years is due to the Rukwa earthquake and its aftershocks that occurred between the Tanganyka and Nyasa systems. In spite of its large magnitude, the Rukwa earthquake caused very little damage to local types of dwellings and no loss of life. With increasing development of urban areas with modern types of houses, there is now increasing risk in East Africa from major earthquakes.     

The earthquake swarm of December 2007 in the Mila region of northeastern Algeria

In December 2007, the Mila region of northeastern Algeria experienced thousands of microearthquakes (0.8????Md????3.9) recorded by eight temporary stations, in addition to permanent stations. Most of the events were too small to be located precisely, but a set of 122 precisely located events shows an alignment of epicenters, extending mainly in a horizontal band at about 1?C2?km depth in a NNW?CSSE direction and concentrated in a small area, 3?km southeast of Jebel Akhal, a small rocky hill between the Beni Haroun dam/reservoir and the Oued Athmania reservoir. The reservoirs are connected by pipelines, and a pumping station ensures water can be transferred between them at transient pressures of up to 80?bars. During the pumping in 2007, only 45?% of the transferred water (~600,000?m³ per day) was recovered at the Oued Athmania reservoir, and a large amount of the slightly pressurized water leaked through defective joints in a tunnel that passes through the Jebel. This water penetrated deeply into the soil with the assistance of preexisting fractures, faults, and karsts. Nine days after the first pumping started, a local increase in pore fluid pressures at shallow depths triggered seismicity southeast of Jebel Akhal, where the faults were probably close to failure. The focal mechanisms show a near vertical N?CS strike-slip fault plane under regional NW?CSE tectonic compression. One of the fault plane solutions is consistent with the NNW?CSSE direction along which the seismic events are aligned. Furthermore, a long-term comparison of the seismic activity in the region versus water levels behind the dam and the pumping of water shows that the earthquake swarm was a one-off event related to the pumping operation.     

The Tasman Sea earthquake of 25 November 1983 and stress in the Australian plate

The Tasman Sea earthquake of 25 November 1983 was large enough (M₀ ≈ 1.1× 10¹⁸ Nm) to be recorded world-wide and provide information on the state of intraplate stress in the lithosphere beneath the Tasman Sea. The earthquake occurred beneath the abyssal plain at a depth of about 25 km and was associated with almost pure dip-slip faulting. The direction of the pressure axis of the focal mechanism is similar (139 degrees E of N) to those observed from the nearby Australian mainland. Hence both the oceanic Tasman Sea and continental Australia appear to be part of the same stress regime. However, the direction of stress in this part of the Australian plate does not coincide with the north-south direction of motion of the plate and therefore forces other than the ridge push must be invoked to generate the stresses observed.     

The Aegean Sea (Greece) earthquake sequence of 25 March 1986: An application of the ν-value method for earthquake prediction

A technique based on the ν-value, which is defined by % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaSGbaeaaca% GGOaGafqiXdqNbaebacaGGPaWaaWbaaSqabeaacaaIYaaaaaGcbaWa% a0aaaeaacqaHepaDdaahaaWcbeqaaiaaikdaaaaaaaaaaaa!3CEB!\[{{(\bar \tau )^2 } \mathord{\left/ {\vphantom {{(\bar \tau )^2 } {\overline {\tau ^2 } }}} \right. \kern-\nulldelimiterspace} {\overline {\tau ^2 } }}\], where τ is the time interval between two adjacent earthquakes and indicates the pattern of time sequences of earthquakes, has been applied to the 25 March 1986 Aegean Sea (Greece) earthquake (M _L = 5.2) in an attempt to discover temporal changes in seismicity. The analysis of several earthquake sequences revealed that low ν-values preceded the occurrence of relatively large earthquakes. The ν-value technique may be used for monitoring the seismicity changes.     

Study of the 26 December 2011 Aswan earthquake,Aswan area,South of Egypt

The source process and parameters for a moderate earthquake of magnitude Ml 4.1 that occurred on the Kalabsha fault at the Aswan area are analyzed. The derived focal mechanisms of this event and other two aftershocks using polarities of P, SV, and SH waves show strike-slip fault with minor vertical movement of normal type. The solutions give two nodal planes trending ENE–WSW and NNW–SSE in close agreement with the surface traces of the faults crossing the area. The movement is right lateral along the first plane while left lateral along the second one. The rupture process characterization of this event has been investigated by using the empirical Green’s function deconvolution method. By inversion only for the P wave part of the records of these three events (main and other two aftershocks), the source time function for the master events and the azimuthally variations in the (RSTF) pulse amplitude are retrieved for estimating the rupture directivities. The estimated rupture direction is combined with the P-wave focal mechanisms for the three events to identify the fault plane solution for these earthquakes. Based on the width, amplitudes, and numbers of the isolated source time functions, a complex bi-lateral rupture of the studied earthquake is delineated. The source parameters of the master event is calculated and the derived corner frequencies f _o for P-wave spectra show a value of 6.6 Hz; the seismic moment (M _o ) is 4.2?×?10²² Nm; the average displacement (U) is 0.5 m; fault radius (r) 40 m; the average value of the stress drops (Δσ) is 0.6 Mpa, and the moment magnitude (M _w ) is 4.4.     

Fault-plane solution and tectonic implications of the Pattan, Pakistan earthquake of December 28, 1974

A large destructive earthquake occurred on December 28, 1974 on the western bank of the Indus River near the village of Pattan. The earthquake reportedly killed 5,300 persons, injured 17,000 and left 60,000 people homeless. A seismicity map of the region is presented for the period January, 1963, to March, 1974 on a Mercator projection. Two main linear trends are recognized on the epicenter map. The northwest trend, beginning at 32.3°N, 76.6°E terminates at the southwest alignment of epicenters beginning at 36.0°N, 73.5°E and ending at 33.0°N, 71.0°E. The Pattan earthquake occurred near the junction of the two linear trends. A fault-plane solution for this earthquake has been determined from an analysis of teleseismic P-wave first-motion and S-wave polarization data. The strike and dip of the two nodal planes are N65°E, 68°SE and N50°E, 23°NW, respectively. The solution is compatible with and indicates underthrusting of the Indian plate in this region in the NNW direction along a thrust zone striking northeast.     

Abnormal animal behaviour as a precursor of the 7 December 1988 Spitak,Armenia, earthquake

This paper relates some facts about abnormal animal behaviour prior to several Armenian earthquakes. The catastrophic Spitak, northern Armenia, earthquake of 7 December 1988, M = 7, I ₀ = X, was preceded by extensive occurrences of abnormal animal behaviour. Proof was established by questioning residents in the area and by distributing specially prepared questionnaires shortly after the event. Approximately 200 reports from 50 sites were examined. The raw data recorded included lists of different types and locations of species that have shown abnormal responses to an impending earthquake, distribution of anomalous occurrences over the area, and precursor times. It is concluded that specially conducted observations of animal behaviour as a possible premonitory phenomenon is both useful and necessary.     

Seismoacoustic effects of the Hovsgol earthquake (M w = 4.9) of December 5, 2014

Doklady Earth Sciences - The results of study of the Hovsgol earthquake with M w = 4.9, which occurred on December 5, 2014, in the northern part of Hovsgol Lake in Mongolia, are presented. An...     

Seismicity pattern in north Sumatra-Great Nicobar region: In search of precursor for the 26 December 2004 earthquake

We analyse the seismicity pattern including b-value in the north Sumatra-Great Nicobar region from 1976 to 2004. The analysis suggests that there were a number of significant, intermediate and short-term precursors before the magnitude 7.6 earthquake of 2 November 2002. However, they were not found to be so prominent prior to the magnitude 9.0 earthquake of 26 December 2004 though downward migration of activity and a 50-day short-term quiescence was observed before the event. The various precursors identified include post-seismic and intermediate-term quiescence of 13 and 10 years respectively, between the 1976 (magnitude 6.3) and 2002 earthquakes with two years (1990–1991) of increase in background seismicity; renewed seismicity, downward migration of seismic activity and foreshocks in 2002, just before the mainshock. Spatial variation in b-value with time indicates precursory changes in the form of high b-value zone near the epicenter preceding the mainshocks of 2004 and 2002 and temporal rise in b-value in the epicentral area before the 2002 earthquake.     

Strong motion scenario of 25th November 2000 earthquake for Absheron peninsula (Azerbaijan)

Urban earthquake scenario requires compilation and interpretation of topographical, geological, geotechnical, macroseismic, and instrumental data, along with identification of proper ground motion prediction and site response analysis. Within the intensive city planning and infrastructure improvement of Baku city (the capital of Azerbaijan), and due to land and water instabilities, intensified landslides, and increasing seismic activity, Absheron peninsula has turned into one of the strategic earthquake case studies, representing exposure to earthquake hazard in the region. The last strongest 25th November 2000 earthquake revealed that the peninsula was severely vulnerable to seismic events, since there was a lack of public awareness of seismic disaster and its consequences, and there were not any preventive measures which might have been derived from the scenario-based simulations and prediction of strong motion distribution over the area. In the present work, integrated analysis of seismicity, engineering geology, geomorphology, topography, and site response is used to model strong motion dynamics in terms of peak ground acceleration distribution and intensity level for Absheron peninsula along with Baku city. The strong motion scenario of the 25th November 2000 earthquake shows that the larger area of the peninsula coincides with the VIII–IX intensity level, including Baku city. The scenario distribution can be valuable in all phases of the disaster management process.     

Modeling of source parameters of the 15 December 2015 Deogarh earthquake of M<Subscript>w</Subscript> 4.0

We herein present source parameters and focal mechanism of a rare cratonic upper crustal earthquake of M_w4.0, which occurred at 8 km depth (centroid depth) below a region near Deogarh, Jharkhand. For our study, we used broadband waveform data from a seismic network of 15 three-component seismographs in the eastern Indian craton. The average seismic moment, moment magnitude and source radius are estimated to be 1.1 × 10¹⁵ N-m, 4.0 and 180.6 m, respectively. The high average stress drop of 14.27 MPa could be attributed to its lower-crustal origin. The mean corner frequency is calculated to be 4.1 Hz. To study the source mechanism, we perform a deviatoric constrained full waveform moment tensor inversion of multiple point sources on the band-passed (0.06 – 0.14 Hz) broadband displacement data of the Deogarh event, using ISOLA software. The best fit is obtained for the source at 8 km centroid depth, with a moment magnitude 3.7, and a right-lateral strike-slip mechanism with strike 162°, dip 72° and rake 169°. The P-axis orients N24°E, which is parallel to the direction of the absolute plate motion direction of Indian plate, while T-axis orients E-W, which is parallel to the strike of the pre-existing Damodar Graben (DG) of Gondwana age. The occurrence of this earthquake is attributed to the neotectonic reactivation of a fault associated with the E-W trending DG shear zone.     

The Asian Tsunami disaster,December 2004

The tragic scenes of human suffering in the wake of the Asian tsunami in late December 2004 have thrown into sharp relief the Earth's destructive power (Fig. 1 ). Caused by a tectonic event off the coast of Sumatra, it could be described as a very large earthquake, an unusual tsunami and a massive disaster. Or, with a longer view, it could be considered a normal feature of a convergent plate boundary. Both views are correct.

Figure 1 Open in figure viewer PowerPoint Mass destruction after the tsunami hit the village on the sand bar at Phi Phi Island, Thailand, with unscathed limestone hills behind (Rex Features).