دانلود رایگان مقاله انگلیسی انتشار داده های لحظه ای زمین لرزه: کاربرد آمار Hurst در ترسیم خوشه های موقت - اشپرینگر 2018

ABSTRACT

Sequential cumulative moment release data of macroearthquakes (Mw≥4.3) of seventeen seismic zones (A to Q) belonging to NE-Himalaya, Burmese-Andaman arc and WestSunda arc are analysed by Hurst analysis, a non-parametric statistical procedure to identify clustering of low and high values in a time series. The moment release in a zone occurs in alternate positive, negative and positive sloping segments forming a wave like pattern with intervening small horizontal segment. The negative sloping segments indicate decelerated moment release pattern or temporal slackening of elastic strain release with high b–value (>0.95). The horizontal segment indicates temporal clustering of moderate magnitude events/seismic moments with moderate b-values (0.8–0.95). The positive segment is characterised by accelerated moment release within a short span of time indicating temporal clustering of larger magnitude earthquakes/ seismic moments and exhibit lowest b–value (<0.7). All zones attest moderate to high Hurst K values, range 0.7-0.86. The pattern in Hurst plots, specially a reversal of trend after prolong negative slope is used for earthquake prognostication in the seismic zones. Our analysis shows that most of the zones register a notable reversal of Hurst clustering trend after a prolonged negative slope which is accompanied by a major earthquake near its end. However, South Burma region (Zone-I) and Tripura fold belt and Bangladesh Plain (Zone-K) do not show any moderate or large shock around the end of the negative sloping trend in Hurst plot. Hence, these two zones can be considered more prone to produce moderate to larger earthquakes in future.

CONCLUSIONS

Analysing the Hurst plots for each of the seventeen zones and its relationship with the corresponding b-value of each segments within the Hurst pattern, the following conclusions can be drawn. a) Lack of occurrence of major earthquakes in negative sloping segments indicate decelerated moment release pattern or temporal slackening of elastic strain release compared to the average (mean) moment release rate. This also indicates a temporal clustering of small magnitude earthquakes / seismic moments that exhibit high b–value (> 0.95). b) The horizontal segment in a Hurst plot indicates temporal clustering of moderate magnitude events / seismic moments with moderate b-values (0.8 – 0.95). c) The positive segment in a Hurst plot is characterised by accelerated moment release within a short span of time with temporal clustering of larger magnitude earthquakes / seismic moments and exhibit lowest b–value (<0.7). d) The lower plate as well as the southern portion of the upper plate of Burmese Andaman arc system has gone through a prolonged period of elastic strain release generation earthquakes significantly lower than the average from the year 2005 to 2013. e) The entire West Sunda arc and the northern portion of the upper plate of the Burmese Andaman arc give evidence of a prominent period of elastic strain release that starts approximately from year 1995 and continued up to 2015. f) The period of elastic strain release for NE Himalaya including Tibet (NEHT) is even longer and starts approximately from 1992 and continues up to the recent times. g) The negative sloping segments always end with a high magnitude event to reverse the trend of moment release. So a prolonged negative segment without a moderate to large earthquake may be regarded as an earthquake precursor. Following this, the south Burma zone and Tripura fold belt and Bangladesh plain (zone I and K), have not yet register any moderate to large earthquake even after an extended period of smaller elastic strain release. So this two zones may be treated as seismically vulnerable.