Time-predictable model applicability for earthquake occurrence in northeast India and vicinity

Abstract

Abstract. Northeast India and its vicinity is one of the seismically most active regions in the world, where a few large and several moderate earthquakes have occurred in the past. In this study the region of northeast India has been considered for an earthquake generation model using earthquake data as reported by earthquake catalogues National Geophysical Data Centre, National Earthquake Information Centre, United States Geological Survey and from book prepared by Gupta et al. (1986) for the period 1906-2008. The events having a surface wave magnitude of M s ≥ 5.5 were considered for statistical analysis. In this region, nineteen seismogenic sources were identified by the observation of clustering of earthquakes. It is observed that the time interval between the two consecutive mainshocks depends upon the preceding mainshock magnitude (M p ) and not on the following mainshock (M f ). This result corroborates the validity of time-predictable model in northeast India and its adjoining regions. A linear relation between the logarithm of repeat time (T ) of two consecutive events and the magnitude of the preceding mainshock is established in the form LogT = cM p + a, where "c" is a positive slope of line and "a" is function of minimum magnitude of the earthquake considered. The values of the parameters "c" and "a" are estimated to be 0.21 and 0.35 in northeast India and its adjoining regions. The less value of c than the average implies that the earthquake occurrence in this region is different from those of plate boundaries. The result derived can be used for long term seismic hazard estimation in the delineated seismogenic regions.

Long-Term Seismic Hazard Analysis in Northeast Himalaya and Its Adjoining Regions

“…The groundwork results obtained in their previous work (Panthi et al, 2011) have been used as input data in the present work to extended the work further to determine the seismic hazard in each nineteen seismogenic sources.…”

“…Data set for the area bounded by 20˚-32˚ N and 88˚-98˚ E has been considered to study the long-term earthquake hazard prediction (Panthi et al, 2011). This area covers the Eastern Himalayan belt, adjoining southeastern Tibet and northeast India region including Arakan-yoma fold belt and consists of several mountain peaks, thrust, faults and lineaments.…”

“…This area covers the Eastern Himalayan belt, adjoining southeastern Tibet and northeast India region including Arakan-yoma fold belt and consists of several mountain peaks, thrust, faults and lineaments. Compilation of the seismicity data base and delineation of the region into seismogenic sources have already been discussed in detail in (Fig 1) (Panthi et al, 2011). One of the basic requirements for determination of prediction relations is the values of a, b, M max and log m 0 for each seismogenic source zone Table (1). This table shows respectively, the region and code number of each seismogenic source zone as shown in Fig.…”

“…F is the complementary cumulative value of the normal distribution with the mean equal to zero and σ is the standard deviation of the above equation. Given the date and the magnitude of the last event in a seismogenic source along with the uncertainty of the model expressed by its standard deviation σ = 0.26, the probabilities of the occurrence of the next shallow main shocks with M s ≥ 5.5 during the next 10, 20 and 30 years were computed and furnished in Table 3 along with the magnitude of the expected large shallow earthquakes based on the model defined in Equations (4) and (5). In Table 3, the second column gives the name of the seismogenic source and the third column the magnitude of the expected main shock, M f , as used in Equation (5).…”

“…After long debates and discussions a Regional Time-and Magnitude-Predictable Seismicity Model have been accepted and applied successfully in different seismically active regions to estimate the magnitude and the time of occurrence of forthcoming earthquakes. These models have put forward to Central Himalaya and its vicinity (Paudyal et al, 2009); Eastern Anatolia (Sayil, 2005); Taiwan (Wang, 2005); Hindukush Pamir Himalaya (Shanker and Papadimitriou, 2004); China (Qin et al, 2001); Circum-Pacific belt (Papadimitriou et al, 2001); Greece and Japan (Karakaisis, 2000); Alpine-Himalayan belt (Pa-pazochos et al, 1997); North-east India (Shanker and Singh, 1996); Indonesian region (Papadimitriou and Papazachos, 1994); the Aegean area (Papazachos and Papaioannou, 1993); New Guinea-Bismark sea region (Karakaisis,1993); the Western coast of the South and the Central America (Papadimitriou, 1993); Greece (Papazachos, 1989); North-East India Himalaya (Panthi et al, 2011) and others. Applicability of the Time-and Magnitude Predictable model has been tested in northeast India Himalaya and its adjoining regions bounded by 20°-32° N and 88°-98° E, and finally evaluate the seismic hazards in the identified seismogenic sources.…”