Structure of earthquake occurrence in space,time and magnitude

Distributions of time between consecutive earthquakes verify an approximately universal scaling law for stationary seismicity. The shape of these distributions is shown to arise as a mixture of one distribution for short‐distance events and an exponential distribution for far‐off events, the distinction from short and long distances being relative to the size of the region studied. The distributions of consecutive distances show a double power law decay and verify an approximate scaling law which guarantees the simultaneous fulfillment of the scaling laws for time. The interplay between space and time can be seen as well by looking at the distribution of distances for a fixed time separation. These results suggest that seismicity can be understood as a series of intertwined independent continuous‐time random walks, with power law‐distributed waiting times and Lévy‐flight jumps. However, a simple model based on these ideas does not capture the invariance of seismicity under renormalization.     

Lower Miocene (Aquitanien-Burdigalian) palaeobiogeography of the Indian subcontinent

The paper analytically discusses certain palaeoecological criteria in the reconstruction of Lower Miocene (Aquitanian-Burdigalian) palaeobiogeography of the Indian subcontinent. The period is characterised by major marine transgressions and a prolific marine invertebrate and terrestrial vertebrate faunas. Faunal affinities of molluscs from western (Sind-Baluchistan) and eastern (Garo Hills) sectors are distinct and different. Molluscs of Garo Hills show affinity to Burmese species, whereas Sind-Baluchistan species shows similarity to that of the Mediterranean region. Marine molluscs resemble with the present-day taxa of the Arabian Sea and Bay of Bengal, where more than 35% species are common. This similarity is also evidenced by marine elasmobranchs, where approximately 33% species and 86% genera are similar to that of the Recent taxa. Terrestrial mammals show an intermingling of southern U.S.S.R. and African forms along with the presence of probably some groups belonging to the Indian subcontinent.Angiosperms are the dominant group. The Lower Miocene floras of the eastern and the western sectors are entirely different. The palm,Sabal major andPinus are reported from various localities. The climate in the western sector and South India was tropical, whereas in the eastern sector, it was variable.The Lower Miocene period is also marked by the contraction of Sindhu Sea, Bangla Sea and the Burmese Gulf southwards resulting in the final disappearance of the sea by the Pliocene.

---

Zusammenfassung Die Paläobiogeographie des unteren Miocän (Aquitan-Burdigal) läßt sich auf dem indischen Subkontinent aus den palökologischen Daten rekonstruieren. Zu dieser Zeit gab es viele marine Invertebraten und terrestrische Vertebraten-Faunen, die große marine Transgression anzeigen. Die Mollusken des Westens (Find-Baluchistan) und Ostens (Garo-Gebirge) sind unterschiedlich. Die Mollusken des Garo-Gebirges sind mit den Spezies von Burma verwandt. Dagegen sind die Faunen von Sind-Baluchistan für die mediterrane Faunenprovinz typisch. Die marinen Mollusken sind verwandt mit den Faunen des Arabischen Meeres und der Bucht von Bengalen; etwa 35% der Spezies sind gleich. Von den marinen Elasmobranchien sind ungefähr 33 % Spezies und 86% Genera gleich wie man sie in den rezenten Faunen findet. Terrestrische Sänger zeigen eine Mischung von südlicher U.S.S.R. und Afrika mit einigen Teilen des Indischen Subkontinentes.In den Pflanzen-Gruppen herrschen die Angiospermen vor. Die Untermiocän-Flora der östlichen und westlichen Gebiete ist ganz unterschiedlich. Der Palme, dieSabal Major undPinus sind aus verschiedenen Lokalitäten bekannt. Das Klima im Westen und im Süden Indiens war tropisch, im Osten dagegen war es wechselfeucht.Das Untermiocän-Meer im Gebiet Sind, Bangladesh und Burma verschwindet vor dem Pliozän.

---

Résumé Cet article analyse certains critères paléoécologiques dans la reconstitution de la paléogéographie du Miocène inférieur (Aquitanien-Burdigalien) de l'Inde subcontinentale. La période est caractérisée par de grandes transgressions marines et par des faunes abondantes d'invertébrés marins et de vertébrés terrestres. Les affinités fauniques des mollusques sont différentes dans les secteurs occidentaux (Sind-Baluchistan) et orientaux (Garo Hills). Les mollusques des Garo Hills montrent des affinités avec les espèces de Burma, tandis que les espèces de Sind-Béloutchistan montrent des similitudes avec celles de la région méditerranéenne. Les mollusques marins ont des ressemblances avec les taxons actuels de la Mer d'Arabie et du Golfe du Bengal, où plus de 35% des espèces sont les mÊmes. Cette similarité vaut aussi pour les élasmobranches marin, dont 33% des espèces et 86% des genres ressemblent aux taxons récents. Les mammifères terrestres montrent un mélange de formes du sud de l'U.S.S.R. et de formes africaines, allant de pair avec la présence de certains groupes probables appartenant au sous-continent indien.Les angiospermes forment le groupe dominant. Les formes du Miocène inférieur des secteurs orientaux et occidentaux sont entièrement différentes. Le palmier, le grand Sabal et le pin, sont connus dans différentes localités. Le climat dans le secteur occidental et dans l'Inde méridionale était tropical, tandis que dans le secteur oriental, il était variable.La période du Miocène inférieur est également marquée par le rétrécissement de la Mer de Sindhu, de la Mer de Bangla et du Golfe de Burma vers le sud, avec comme résultat la disparition finale de la mer au Pliocène.

---

(Aquitanian Nurdigalian) . . (Sind- Beluchistan) (Garo Hills) . , . : 35% . Elasmobranchs 33 % 86 % . , . . , Sabal major . , , , , , — . Sindhu, .

     

Correlating recurrent radon precursors with local earthquake magnitude and crust strain near the Chihshang fault of eastern Taiwan

The active Chihshang fault in the southern segment of longitudinal valley of eastern Taiwan is part of the suture boundary between the Eurasia plate and the Philippine Sea plate. Radon anomalies in groundwater were recorded prior to three major earthquakes—(1) 2003 M _w = 6.8 Chengkung, (2) 2006 M _w = 6.1 Taitung, and (3) 2008 M _w = 5.4 Antung. The epicenters were located 24, 52, and 13 km, respectively, from the radon-monitoring well (D1) in the Antung hot spring about 3 km southeast of the Chihshang fault. Prior to the three major earthquakes, radon decreased from background levels of 787 ± 42, 762 ± 57, and 700 ± 57 pCi/L to minima of 326 ± 9, 371 ± 9, and 480 ± 43 pCi/L, respectively. Based on the radon volatilization model and the rock dilatancy model, this paper correlates the observed radon minima with local earthquake magnitude and crust strain. The correlation is a useful means of forecasting local disastrous earthquakes in the southern segment of longitudinal valley of eastern Taiwan.     

An application of regional time and magnitude predictable model for long-term earthquake prediction in the vicinity of October 8, 2005 Kashmir Himalaya earthquake

A regional time and magnitude predictable model has been applied to estimate the recurrence intervals for large earthquakes in the vicinity of 8 October 2005 Kashmir Himalaya earthquake (25°–40°N and 65°–85°E), which includes India, Pakistan, Afghanistan, Hindukush, Pamirs, Mangolia and Tien-Shan. This region has been divided into 17 seismogenic sources on the basis of certain seismotectonics and geomorphological criteria. A complete earthquake catalogue (historical and instrumental) of magnitude Ms ≥ 5.5 during the period 1853–2005 has been used in the analysis. According to this model, the magnitude of preceding earthquake governs the time of occurrence and magnitude of future mainshock in the sequence. The interevent time between successive mainshocks with magnitude equal to or greater than a minimum magnitude threshold were considered and used for long-term earthquake prediction in each of seismogenic sources. The interevent times and magnitudes of mainshocks have been used to determine the following predictive relations: logT _t = 0.05 M _min + 0.09 M _p − 0.01 log M ₀ + 01.14; and M _f = 0.21 M _min − 0.01 M _p + 0.03 log M ₀ + 7.21 where, T _t is the interevent time of successive mainshocks, M _min is minimum magnitude threshold considered, M _p is magnitude of preceding mainshock, M _f is magnitude of following mainshock and M ₀ is the seismic moment released per year in each seismogenic source. It was found that the magnitude of following mainshock (M _f) does not depend on the interevent time (T _t), which indicates the ability to predict the time of occurrence of future mainshock. A negative correlation between magnitude of following mainshock (M _f) and preceding mainshock (M _p) indicates that the larger earthquake is followed by smaller one and vice versa. The above equations have been used for the seismic hazard assessment in the considered region. Based on the model applicability in the studied region and taking into account the occurrence time and magnitude of last mainshock in each seismogenic source, the time-dependent conditional probabilities (PC) for the occurrence of next shallow large mainshocks (Ms ≥ 6.5), during next 20 years as well as the expected magnitudes have been estimated.     

印度陆块新生代两次仰冲事件及其构造驱动机制:论印度洋、特提斯和欧亚板块相互作用

印度陆块与欧亚大陆的碰撞是印度洋扩张和特提斯洋闭合综合作用的结果。本文通过综合分析和研究提出这3个板块的相互作用致使印度陆块发生过2次向北的仰冲:早期(古新世末-始新世初,~57Ma)仰冲受其超高速运动(140mm/yr)的驱动,与特提斯之间产生的速度差致使两者间的边界发生破裂,密度小的印度陆块沿印度洋东经90°海岭和马尔代夫岛链向北仰冲到特提斯洋壳之上,两者的叠加导致印度陆块北缘——特提斯喜马拉雅地壳增厚(~70km)并且沉积了一套造山磨拉石——柳曲砾岩;晚期(渐新世-中新世之交,~25Ma)仰冲发生在碰撞后,由于高喜马拉雅结晶岩系沿主中央冲断带和藏南拆离断裂发生的垂向挤出,位于上盘的特提斯喜马拉雅沉积盖层同时发生重力垮塌,沿大喜马拉雅反冲断裂仰冲到冈底斯岩浆岩带之上并且造成后者的隆升和前陆下陷,其北缘充填了一套造山磨拉石沉积——大竹卡砾岩。这两次构造事件均受印度陆块的快速运动驱动。此外,在印度陆块超高速运动的挤压下,特提斯洋可能在早白垩世之后就停止了扩张,而老的洋壳不是俯冲消减了就是被仰冲的印度陆块掩盖了,这解释了为什么雅鲁藏布江缝合带只存早白垩世蛇绿岩。印度洋内东经90°海岭和马尔代夫岛链构成印度陆块的南东和南西边界,前者呈右行走滑,后者呈左行走滑,两者勾画出印度陆块向北漂移的轨迹。     

The 20 May 2016 Petermann Ranges earthquake: centroid location,magnitude and focal mechanism from full waveform modelling

Ground velocity records of the 20 May 2016 Petermann Ranges earthquake are used to calculate its centroid-moment-tensor in the 3?D heterogeneous Earth model AuSREM. The global-centroid-moment-tensor reported a depth of 12?km, which is the shallowest allowed depth in the algorithm. Solutions from other global and local agencies indicate that the event occurred within the top 12?km of the crust, but the locations vary laterally by up to 100?km. We perform a centroid-moment-tensor inversion through a spatiotemporal grid search in 3?D allowing for time shifts around the origin time. Our 3?D grid encompasses the locations of all proposed global solutions. The inversion produces an ensemble of solutions that constrain the depth, lateral location of the centroid, and strike, dip and rake of the fault. The centroid location stands out with a clear peak in the correlation between real and synthetic data for a depth of 1?km at longitude 129.8° and latitude –25.6°. A collection of acceptable solutions at this centroid location, produced by different time shifts, constrain the fault strike to be 304?±?4° or 138?±?1°. The two nodal planes have dip angles of 64?±?5° and 26?±?4° and rake angles of 96?±?2° and 77?±?5°, respectively. The southwest-dipping nodal plane with the dip angle of 64° could be seen as part of a near vertical splay fault system at the end of the Woodroffe Thrust. The other nodal plane could be interpreted as a conjugate fault rupturing perpendicular to the splay structure. We speculate that the latter is more likely, since the hypocentres reported by several agencies, including the Geoscience Australia, as well as the majority of aftershocks are all located to the northeast of our preferred centroid location. Our best estimate for the moment magnitude of this event is 5.9. The optimum centroid is located on the 20?km surface rupture caused by the earthquake. Given the estimated magnitude, the long surface rupture requires only ～4?km of rupture down dip, which is in agreement with the shallow centroid depth we obtained.     

Long-term earthquake prediction in the North Pacific seismic zone based on the time and magnitude predictable model

Earthquake recurrence intervals for large and great shallow mainshocks in 12 seismogenic sources along the North Pacific seismic zone (Alaska-Aleutians-Kamchatka-Kuril Islands) have been estimated and used for the determination of the following relations:

Integration and magnitude homogenization of the Egyptian earthquake catalogue

The aim of the present work is to compile and update a catalogue of the instrumentally recorded earthquakes in Egypt, with uniform and homogeneous source parameters as required for the analysis of seismicity and seismic hazard assessment. This in turn requires a detailed analysis and comparison of the properties of different available sources, including the distribution of events with time, the magnitude completeness, and the scaling relations between different kinds of magnitude reported by different agencies. The observational data cover the time interval 1900–2004 and an area between 22°–33.5° N and 25°–36° E. The linear regressions between various magnitude types have been evaluated for different magnitude ranges. Using the best linear relationship determined for each available pair of magnitudes, as well as those identified between the magnitudes and the seismic moment, we convert the different magnitude types into moment magnitudes M _W, through a multi-step conversion process. Analysis of the catalogue completeness, based on the M _W thus estimated, allows us to identify two different time intervals with homogeneous properties. The first one (1900–1984) appears to be complete for M _W ≥ 4.5, while the second one (1985–2004) can be considered complete for magnitudes M _W ≥ 3.     

Hydrochemical and isotopic investigation of a tropical wetland system in the Indian subcontinent

The study reported here is a part of an attempt to establish a comprehensive hydrochemical and isotopic baseline for a tropical wetland system as background data for a range of applications. Surface water samples of Vembanad Lake were collected from 20 stations in three seasons during the period 2007–2009. The analytical results were subjected to different chemical classification techniques to understand processes affecting the chemical concentration of waters. The Piper diagram classified the water samples as 100% alkali group in pre-monsoon followed by 15% in monsoon and 85% in post-monsoon, and for anions 100% samples were of strong acids followed by 90% in monsoon and 100% in post-monsoon season. The plot to decipher the mechanism controlling water chemistry placed the Vembanad Lake in the region of precipitation and rock dominance in the monsoon season and in the field of saline water dominance in pre-monsoon and post-monsoon season. The positive values for the chloro-alkaline indices in pre and post-monsoon season promoted cation exchange in the system. The stable isotopes of water samples ranged from ?20.21 to +17.0‰ and ?5.6 to +3.34‰ for δ ²H and δ ¹⁸O, respectively. The most depleted δ values observed in the monsoon are due to the amount effect. The high enrichment observed in pre-monsoon is primarily due to evaporation and salinity mixing. The variation of isotopes in the whole system point toward the fact that salinity mixing can be indicated by the δ ¹⁸O variation and δ ²H indicates the evaporation effect. The plot of δ ¹⁸O with chloride concentration showed precipitation dominance in the monsoon season, mixing of saline water and evaporation in pre-monsoon season, whereas the post-monsoon samples plot in both fresh and saline region.     

鲁甸地震(Ms6.5)临震预测、中期预测及中地壳流变结构

2014年8月3日16时30分, 在云南省昭通市鲁甸县(27.1°N, 103.3°E)发生M_s6.5地震, 震源深度10 km, 死亡617人, 失踪112人, 受伤3 143人, 受灾人口108.84万人.根据月亮赤纬角、太阳黑子极值年等周期变化及两者的叠加效应, 总结出2013—2014年是云南强震高危期, 具备M_s7地震的发生条件.次年, 利用基础SW前兆仪的临震预测指纹法信息, 制定了2014年底211号地震预测表, 预测了2014年8月四川(26.18°N, 105.33°E)将发生M_s5.3地震发生.2014年8月3日云南鲁甸M_s6.5地震表明: 这次地震的指纹法预测时间相差1天, 震中相差226 km, 震级误差M_s1.2.通过构造背景、地壳速度结构和震源机制研究, NW向的包谷垴-小河左旋走滑断裂是鲁甸地震的发震断裂.中下地壳低速(高导)体与包谷垴-小河断裂交接部位是流变界面能量释放的位置, 即本次地震的震源位置, 为板内地震三层次构造模式提供了一个新的案例.      

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...     

Estimation of maximum magnitude (M max ): Impending large earthquakes in northeast region,India

In the present study, the cumulative seismic energy released by earthquakes (M _w ≥ 5) for a period of 1897 to 2009 is analyzed for northeast (NE) India. For this purpose, a homogenized earthquake catalogue in moment magnitude (M _w ) has been prepared. Based on the geology, tectonics and seismicity, the study region is divided into three source zones namely, 1: Arakan-Yoma Zone (AYZ), 2: Himalayan Zone (HZ) and 3: Shillong Plateau Zone (SPZ). The maximum magnitude (M _max ) for each source zone is estimated using Tsuboi’s energy blocked model. As per the energy blocked model, the supply of energy for potential earthquakes in an area is remarkably uniform with respect to time and the difference between the supply energy and cumulative energy released for a span of time, is a good indicator of energy blocked and can be utilized for the estimation of maximum magnitude (M _max ) earthquakes. The proposed process provides a more consistent model of gradual accumulation of strain and non-uniform release through large earthquakes can be applied in the assessment of seismic hazard. Energy blocked for source zone 1, zone 2 and zone 3 regions is 1.35×10¹⁷ Joules, 4.25×10¹⁷ Joules and 7.25×10¹⁷ Joules respectively and will act as a supply for potential earthquakes in due course of time. The estimated M _max for each source zone AYZ, HZ, and SPZ are 8.2, 8.6, and 8.7 respectively. M _max obtained from this model is well comparable with the results of previous workers from NE region.     

Seismic evidence of increased tectonothermal activity near the Oberpfalz deep continental drilling location (SE Germany)

The success of ultradeep drilling projects, as e.g. within the German Continental Deep Drilling Programme (Kontinentales Tiefbohrprogramm, KTB) in the Oberpfalz strongly depends on the thermal and geological-tectonic environment of the well. In the present paper we apply the correlation of elevated temperatures and seismic reflectivity of the lower continental crust to the deep seismic network of the Oberpfalz. The results together with the correlation to other geoscientific data indicate increased temperatures in the area of the KTB location. These temperatures are most probably related to influences of the Eger graben and possibly are not yet measured at the surface using heat flow determinations.

---

Zusammenfassung Der Erfolg ultratiefer Bohrungen, wie etwa in der Oberpfalz im Rahmen des deutschen Kontinentalen Tiefbohrprogramms (KTB), hängt sehr stark vom thermischen und geologisch-tektonischen Umfeld der Bohrung ab. In der vorliegenden Arbeit wird die Korrelation von erhöhten Temperaturen und guter Reflektivität der kontinentalen Unterkruste angewandt auf das seismische Netz der DEKORP 4 und KTB Linien in der Oberpfalz. Aufgrund der Ergebnisse und anderer geowissenschaftlicher Resultate sind höhere Temperaturen als vorher berechnet im Bereich der Tiefbohrung zu erwarten. Diese dürften im Zusammenhang mit dem westlichen Ende des Eger Grabens stehen.

---

Résumé Le succès de sondages très profonds, comme celui qui est envisagé dans le Haut Palatinat dans le cadre du programme allemand de sondages profonds continentaux (Kontinental Tiefbohrprogramm: KTB) est étroitement lié à l'environnement thermique et tectono-géologique des forages. Dans cette note, la corrélation entre les hautes températures et la réflectivité sismique est appliquée au réseau sismique fourni par les profils DEKORP 4 et KTB dans le Haut Palatinat. Les résultats obtenus, joints à d'autres données géologiques, laissent prévoir dans la région du KTB des températures plus élevées que celles qui étaient envisagées jusqu'ici. Ces températures élevées sont probablement en relation avec l'extrémité ouest du graben d'Eger et n'ont pas encore été repérées en surface par les mesures du flux de chaleur.

---

170- - / / . , . 18% , : KTst 0=950 (Stefan A), KTst 1=700 (Westfal D), KTst 3=400 (Westfal C), KTst 4a=330 (Westfal ), KTst 4a=322 (Westfal C), KTst 4=320 (Westfal C), KTst 5=300 (Westfal C), KTst 6=270 (Westfal C). . , . , . . , , , - . , 43 - 8,2 ³, — 20,5 ³. , , - ; , .

     

Predictability of landfall location and surge height of tropical cyclones over North Indian Ocean (NIO)

Natural Hazards - Forecasting, with precision, the location of landfall and the height of surge of cyclonic storms prevailing over any ocean basin is very important to cope with the associated...     

The M w 8.6 Indian Ocean earthquake on 11 April 2012: Coseismic displacement, Coulomb stress change and aftershocks pattern

The M _w 8.6 Indian Ocean earthquake occurred on April 11, 2012 near the NW junction of three plates viz. Indian, Australian and Sunda plate, which caused widespread coseismic displacements and Coulomb stress changes. We analyzed the GPS data from three IGS sites PBRI, NTUS & COCO and computed the coseismic horizontal displacements. In order to have in-depth understanding of the physics of earthquake processes and probabilistic hazard, we estimated the coseismic displacements and associated Coulomb stress changes from two rectangular parallel fault geometries, constrained by Global Positioning System (GPS) derived coseismic displacements. The Coulomb stress changes following the earthquake found to be in the range of 5 to ?4 bar with maximum displacement of ～11 m near the epicenter. We find that most of the aftershocks occurred in the areas of increased Coulomb stress and concentrated in three clusters. The temporal variation of the aftershocks, not conformed to modified Omori’s law, speculating poroelastic processes. It is also ascertained that the spatio-temporal transient stress changes may promote the occurrence of the subsequent earthquakes and enhance the seismic risk in the region.