Următorul M7 |
Bine ati venit ca musafir! ( Logare | Inregistrare )
Următorul M7 |
28 Jun 2009, 06:19 PM
Mesaj
#1
|
|
Domnitor Grup: Membri Mesaje: 2.455 Inscris: 6 November 05 Forumist Nr.: 7.211 |
Image of Next Earthquake:
Epicenter: 45.6+-0.1 N, 26.6 +-0.1 E Epicentral Area: 50km in NE-SW Direction and 20 km width Rupture: Uni-Lateral Toward SW Depth Range: 140 –160 km Magnitude: M=7.3+-0.4 Time: 2007+-6 „A long-term earthquake prediction, based on the regularity of earthquake occurrences and a seismic gap theory, is presented. Especially in subduction zones, clear geophysical background (plate tectonics) and short recurrence time allow us to make practical use of the prediction. An M7 intermediate-depth earthquake occurs in the Vrancea region of Romania on average every 20 to 30 years. The last major earthquake occurred in 1986 (M7.2). According to the average rate frequency, we expect a next large earthquake will occur soon. Although a long-term prediction based on regularity of earthquake occurrences has already been carried out by Purcaru (1974) and Enescu et al. (1974), and the predicted M7 earthquake actually occurred in 1977, this prediction was not based on the seismic gap theory and the hypocenter could not have been precisely predicted. Here we show (i) that we can relocate earthquakes since 1934 quite accurately by using the modified joint hypocenter determination method developed by Hurukawa & Imoto (1992), and (ii) that past M7 class earthquakes had occurred at a depth range of 60-140 km with no overlapping of the aftershock areas, and the area at 140-160 km depth remains unbroken. Considering three seismic active time bands in each century characterized by “quasicycles“ of about 100 year identified by Purcaru (1979), and the relocation results, we propose a hypothetical scheme for the occurrence of the M7 Vrancea earthquakes, as follows: a first M7 earthquake occurs in the deeper segment (140-160 km in depth) at the beginning of each century (years 0-10), then a second M7 earthquake occurs in the midst segment (110-140 km in depth) at the midst of each century (years 30- 40), and finally a third M7 earthquake occurs in the shallower segment (80-110 km in depth) at the end of each century (years 70-90). Certainly, the focal depth of old earthquakes is not accurate, since it is estimated from seismic intensity distribution.However, historical M7 earthquakes show a clear dependence of focal depth on the particular active time interval in each century. Purcaru (1974, 1979), Enescu et al. (1974) and Enescu & Enescu (1996, 1999) predicted from the regularity of earthquake occurrence that the next major Vrancea earthquake will occur in this decade. Considering the result of this study and the periodicity of the seismic activity over the past 1000 years, we believe that the possibility of the next M7 earthquake occurring at a depth of 140-160 km by 2010 is very high.” (N. Hurukawa, M. Popa, M. Radulian) Acest topic a fost editat de shapeshifter: 28 Jun 2009, 06:27 PM -------------------- Keep calm and host yourself.
|
|
|
10 Aug 2009, 02:23 PM
Mesaj
#2
|
|
Domnitor Grup: Membri Mesaje: 2.455 Inscris: 6 November 05 Forumist Nr.: 7.211 |
Nu exista informatii suficient de clare privind ceea ce s-a intamplat in zona cu putin timp inainte de producerea cutremurului puternic din 1916. E probabil sa fi existat unele seisme precursoare locale, dar probabil de magnitudine mica, si prin urmare nu exista inregistrari pentru acele evenimente. Sunt disponibile inregistrari pentru cutremurul din 1916, deoarece acesta a fost puternic, fiind inregistrat la statii seismice din Bulgaria, Romania, Ungaria. Cutremurul a fost resimtit pe o suprafata de circa 200.000 de kilometri patrati. Intensitatea seismului a fost de aproape IX grade pe scara Mercalli pe o raza de circa 7-10 km in jurul epicentrului, si de VIII grade pe scara Mercalli pe o raza de circa 20 km in jurul epicentrului. Aria de intensitate VII a inclus, se pare, orasele Sibiu, Ramnicu Valcea, Brasov si s-a intins, de asemenea, pana la nord de Pitesti (dupa cum se relateaza in lucrarea lui Sever din 2005). La Bucuresti intensitatea a fost mai mica, de IV spre IV 1/2 Mercalli.
A impresionat numarul mare de cutremure secundare care au urmat socului principal. Numai in primele 24 de ore de la socul principal din dimineata zilei de 26 ianuarie 1916, in arealul Depresiunea Lovistei-Brezoi-Titesti (Valea Oltului), precum si in zona Arefu-Cumpana-Piscul Negru (catre Cheile Argesului, la coada actualului lac de acumulare Vidraru) au fost resimtite nu mai putin de 30 de cutremure, cu intensitati de la V la VII-VIII grade pe scara Mercalli (in afara socului principal de la ora 9h38 min, cu epicentru la Cumpana-Piscul Negru, adancime focala 21 km si magnitudine 6,4-6,5 pe scara Richter). Seria de cutremure fagarasene moderate si puternice s-a prelungit timp de mai multe luni, pana la inceputul lunii mai 1916 !!!!!! -------------------- Keep calm and host yourself.
|
|
|
Versiune Text-Only | Data este acum: 27 April 2024 - 04:36 PM |