## 1 Introduction  
The Kahramanmaras-Gaziantep _M\({}_{\text{tr}}\)_7.8_ Pazarcik earthquake (EQ) [1] took place on 6 February 2023 at 01:17:35 UTC and was followed within 9 h by the _M\({}_{\text{tr}}\)_7.5_ Elbistan EQ [2] at 10:24:48 UTC, giving rise to the 2023 Kahramanmaras, Turkey, EQ doublet [3]; see Figure 1. According to the International Blue Crescent Relief and Development Foundation [4] situation report, the Turkish Ministry of Interior had announced that the fatal casualties in the Kahramanmaras EQs doublet totaled more than 50,399 lives. Moreover, 8476 people lost their lives in Syria, which was also affected by these EQs. It was one of the deadliest disasters in Turkey and Syria during the last millennium [3]. In total, 16 percent of Turkey's population, that is 14 million people, were affected by these catastrophic events [4]. Almost two weeks before the Kahramanmaras EQ doublet, i.e., on 25 January 2023, a paper was submitted [5] in which a novel procedure for estimating the time of occurrence of an impending strong EQ was presented. This new procedure was based on the combination of the results obtained from natural time analysis (NTA), see below, and non-extensivestatistical mechanics (NESM) pioneered by [PERSON] [6]. [PERSON] [6] introduced a new functional form for the entropy, which is now generally called Tsallis entropy [7; 8; 9; 10; 11; 12; 13; 14; 15; 16]  
\[S_{q}=k_{B}\frac{\left(1-\sum_{i}p_{i}^{q}\right)}{(q-1)}, \tag{1}\]  
where \(q\in\mathcal{R}\) is the entropic index, \(\{p_{i}\}\) are the probabilities for each microstate \(i\) and \(k_{B}\) is the Boltzmann constant. In the case \(q\to 1\), Equation (1) recovers the Boltzmann entropy  
\[S_{B}=-k_{B}\sum_{i}p_{i}\ln p_{i}. \tag{2}\]  
Using a fragment-asperity model [17], [PERSON] and [PERSON] [18] have recently estimated the Tsallis entropy \(S_{q}\) for the case of EQs; for further details, see Section 2.4. It is the combination of the latter quantity with the entropy change \(\Delta S\) under time reversal in NTA that allows the estimation of the occurrence time of the impending EQ [5]. NTA, which is based on a new concept of time termed natural time, was introduced in 2001 [20] and has found useful applications that range from EQ preparatory processes to heart dynamics [21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32] and from atmospheric sciences [33; 34; 35; 36] to finance [37]; for a recent review, see [38]. It was originally focused on the discrimination of the low-frequency (\(f\leq 1\) Hz) electric signals that are observed before EQs, which are called Seismic Electric Signals (SES) [23; 39; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 46; 47; 48; 49; 50; 51; 52; 53], from similar-looking signals of man-made origin [54]. The physical properties of SES [23; 42] provide information on the magnitude \(M\) of the impending EQ, on the probable epicentral area, and an estimation of its occurrence time. In the first publications by [PERSON] et al. [20; 54], it was shown that NTA may reveal that SES exhibited critical dynamics, while it has been also used for the identification of criticality in the seismicity inside the probable epicentral area. As will be further elaborated in Section 2.3, NTA there may provide a first estimate of the occurrence time of the impending EQ [20; 44; 55; 56] (see also Chapter 7 of [23] and Chapters 5 and 9 of [38]). Additionally, NTA provides means to identify temporal correlations between EQ magnitudes (see Section 6.3 of [23] and references therein), which is a very hot topic, see, e.g., the recent meta-analysis by [PERSON]  
Figure 1: The epicenters (red stars) of all EQs reported by AFAD with magnitude \(M\geq\) 2.0 during the period 1 January 2020 to 31 December 2022 (see Section 2.1). The yellow stars depict the epicenters of the Kahramanmaras-Gaziantep \(M_{\rm u}\)7.8 Pazarcik EQ [1] and the \(M_{\rm u}\)7.5 Elbistan EQ [2] that occurred on 6 February 2023 at 01:17:34 UTC and 10:24:48 UTC, respectively. The black thick lines depict the tectonic plate boundaries [19].