Earthquake frequency-magnitude distribution and fractal dimension in mainland Southeast Asia

Abstract

The 2004 Sumatra and 2011 Tohoku earthquakes highlighted the need for a more accurate understanding of earthquake characteristics in both regions. In this study, both the a and b values of the frequency-magnitude distribution (FMD) and the fractal dimension (D C ) were investigated simultaneously from 13 seismic source zones recognized in mainland Southeast Asia (MLSEA). By using the completeness earthquake dataset, the calculated values of b and D C were found to imply variations in seismotectonic stress. The relationships of D C -b and D C -(a/b) were investigated to categorize the level of earthquake hazards of individual seismic source zones, where the calibration curves illustrate a negative correlation between the D C and b values (D c = 2.80 − 1.22b) and a positive correlation between the D C and a/b ratios (D c = 0.27(a/b) − 0.01) with similar regression coefficients (R 2 = 0.65 to 0.68) for both regressions. According to the obtained relationships, the Hsenwi-Nanting and Red River fault zones revealed low-stress accumulations. Conversely, the Sumatra-Andaman interplate and intraslab, the Andaman Basin, and the Sumatra fault zone were defined as high-tectonic stress regions that may pose risks of generating large earthquakes in the future.

Anisotropic Rayleigh-wave phase velocities beneath northern Vietnam

“…However, northern Vietnam is a relatively poorly studied region seismologically, lacking in a variety of models for comparison Pailoplee and Choowong 2014). New models providing observations at greater depths (asthenosphere and below) would be of great interest to investigate the effects of the influence of the deeper part of the RRSZ (Knapmeyer- Endrun et al 2013).…”

Seismic hazards in Thailand: a compilation and updated probabilistic analysis

“…The advantage of this PSHA is that it was compiled from the most up-to-date data and was constrained theoretically, in particular for the paleoseismological data that are a significant factor in reliably estimating the characteristic long period and large earthquake effect to improve the accuracy of the PSHA. The a and b values of the Gutenberg-Richter relationships (seismicity parameters) were also used according to the most reliable statistical investigation (Pailoplee and Choowong 2014). By using the suitable strong ground-motion attenuation relationship, both ground shaking and probability maps were developed.…”

“…1b). The a and b values of the Gutenberg-Richter relationships of each SSZ, including the fault data within each SSZ, were provided by the most up-to-date data provided by Pailoplee and Choowong (2014), as given in Table 3. However, the a and b values of the SSZs H and K are not available, and both values proposed by Pailoplee and Choowong (2013) are employed for the SSZs H and K. In final, 75 earthquake sources of the seismogenic faults and SSZs were recognized in this PSHA.…”

“…The SSZs of mainland Southeast Asia have been modified (Fig. 1b) (Pailoplee and Choowong 2013), the seismicity data have been updated to the present (Pailoplee and Choowong 2014), new paleoseismological data have become available (Figs. 1b,2), and suitable attenuation models for Thailand have been constrained differently (Chintanapakdee et al 2008).…”

“…During the past century , seven published isoseismal maps (Pailoplee 2012) have depicted that Thailand and, in particular, the northern and western parts have been subjected to earthquakes of an intensity range of II-VII on the modified Mercalli intensity (MMI) scale according to both local-moderate (M w of 5.0-5.9) and distant-major (M w of 7.0-7.9) earthquakes. Based mainly on the present-day instrumental seismicity data, Pailoplee and Choowong (2014) investigated and revealed that most of the seismic source zones in mainland Southeast Asia area are seismically active. In addition, according to the region-time-length algorithm (Huang et al 2002), Sukrungsri and Pailoplee (2015) proposed four prospective areas along the Sumatra-Andaman subduction zone that might experience a major earthquake in the future, namely (1) Sittwe city in western Myanmar; (2) the area offshore of the northern Nicobar Islands; (3) Aceh city in the northernmost area of Sumatra Island; and (4) the area offshore of western Sumatra Island.…”