A Practical and Effective Solution to Earthquake (EQ) Catastrophe: Case Studies

1. Introduction

Since 1970 every occasion of catastrophic earthquakes, particularly in Anatolia (Figure 1), has been observed and investigated. The authors reached a concise and comprehensive conclusion that buildings and the other civil structures founded on/in rocky ground have not been affected noticeably from any earthquake in respective regions. Furthermore, casualties have been zero. The main reason behind this is that a saturated rocky ground compared with saturated soil has; (a) zero liquefaction potential, (b) million times higher modulus of elasticity,

Figure 1.

Tectonic outline of the Anatolia (Turkey) depicting North Anatolian Fault and the other major fault systems

(c) appreciably higher strength, (d) extremely low potential to create resonance in case of two-storey (.nd taller buildings, and (e) extremely low risk of bedding fault (Table 1 and Table 2). In Table 2, the EQ energy – distance relationship is based on equations given in Kayal (2006), Idriss (1991), Ulusay et al. (2004), and references therein. Peak ground acceleration (PGA) for (a) rock, (b) soil, and (c) soft soil is calculated by the equation;

Where Mw is magnitude and R_e denotes distance to epicenter and for (a) rock S_A=S_B=0, (b) soil S_A=1 and S_B=0, and (c) soft soil S_A=0 and S_B=1 (Ulusay et al., 2004). A practical example for soft soil of Bornova is presented herein.

A very recent earthquake hit on 30.10.2020, about 10 km north of Greek island of Samos. It is Samos Island earthquake but people including majority of academicians call it Izmir earthquake. It gave its destructive effect to structures settled only in soil lands. Over one million buildings of Izmir are nearer to epicenter and they are founded in/or rock. It is very clear that none of them has not been affected. Bornova (nose-soil plain) is the farthest settlement of Izmir to the epicenter. Over 99% of casualties is from Bornova and its surrounding soil plains (see Figure 2). M_w(R_e=0) = 6.9, a_max=0.503g. E_(Mw=6.9)= 1.41*10¹⁵ Joule (N.m) by Eq. 2 and E≅74 Hiroshima Atomic Bomb (HAB) by Eq. 3.

For Bornova soft soil (72 km eastwards) a_max=0.105, attenuated from 0.503 to 0.105 in soft soil. The value “0.105” equals to “a_max-value” of M_{w (Re=0 km (Bornova))}= 4.74. E_(Mw=4.74)≅8.3*10¹¹ Joule ≅ 0.04 HAB throughout Eqs. 2-3. Hence, the ratio E_Samos/E_Bornova≅1738 (see Figure 2).

About 50-year one-to-one observations agree with the content of the Table 1. Since 1970s the authors convinced many contractors on scientific base and on the principle stating that “the past is key to the future”. They moved their housing projects from soil grounds to rocky lands particularly and urgently in seismically active regions. Istanbul is the well-known historical city adjacent to North Anatolian Fault (NAF). Over 95% consists of rocky ground. The Maiden and Galata towers are testimonial monuments highlighting that 2-storey (h~6 m) and taller buildings founded in/on rocky grounds resist against earthquake catastrophe explicitly (Figure 3).