A preliminary evaluation of surface latent heat flux as an earthquake precursor

Abstract

Abstract.The relationship between variations in surface latent heat flux (SLHF) and marine earthquakes has been a popular subject of recent seismological studies. So far, there are two key problems: how to identify the abnormal SLHF variations from complicated background signals, and how to ensure that the anomaly results from an earthquake. In this paper, we proposed four adjustable parameters for identification, classified the relationship and analyzed SLHF changes several months before six marine earthquakes by employing daily SLHF data. Additionally, we also quantitatively evaluate the long-term relationship between earthquakes and SLHF anomalies for the six study areas over a 20 yr period preceding each earthquake. The results suggest the following: (1) before the South Sandwich Islands, Papua, Samoa and Haiti earthquakes, the SLHF variations above their individual background levels have relatively low amplitudes and are difficult to be considered as precursory anomalies; (2) after removing the clustering effect, most of the anomalies prior to these six earthquakes are not temporally related to any earthquake in each study area in time sequence; (3) for each case, apart from Haiti, more than half of the studied earthquakes, which were moderate and even devastating earthquakes (larger than M w = 5.3), had no precursory variations in SLHF; and (4) the correlation between SLHF and seismic activity depends largely on data accuracy and parameter settings. Before any application of SLHF data on earthquake prediction, we suggest that anomaly-identifying standards should be established based on long-term regional analysis to eliminate subjectivity. Furthermore, other factors that may result in SLHF variations should also be carefully considered.

Brief Communication: The interaction of clouds with surface latent heat flux variation before the 2011 <i>M</i> = 6.1 Russia earthquake

“…Zhang et al (2013) also gives a similar conclusion after analyzing six strong quakes. However, strictly speaking, how the earthquakes interact with SLHF is still unknown, so we can not totally exclude the possibility that the anomalous SLHF might be related to an earthquake.…”

Pre-seismic anomalies from optical satellite observations: a review

“…The relative power spectrum (RPS) method performs wavelet transform on time series data to realize bandpass filtering, remove long-and short-period components, and retain certain intermediate frequency band information that may be connected with seismic-related signal changes and is expressed in the form of power spectrum. RPS method was used to analyze BT anomalies of the 2008 Wenchuan earthquake (Zhang et al, 2010). Figure 10 presents the obvious BT anomalies from 25 April to 19 June 2008 over the Longmenshan fault zone and demonstrates the good results of the RPS method.…”

“…6, occurred approximately 10 days before the inland Pu'er earthquake (23.8092 • N, 101.15 • E) on 2 June 2007. Conversely, the study of Zhang et al (2013) indicates that no significant anomalous variation of SLHF exists prior to ten studied marine or coastal earthquakes, and that data accuracy and parameter settings have an important effect on quantification of the correlation between SLHF anomaly and earthquake's occurrence.…”

“…Changes in pressure between rocks due to seismic activity are believed to result in greenhouse gas emissions and local greenhouse effect (Choudhury et al, 2006;Singh et al, 2010a;Zoback and Gorelick, 2012). The experimental results show that gases, such as CH 4 and CO 2 , can obtain energy from the transient electric field and cause a temperature increase.…”

Multi-parametric analysis of earthquake precursors

“…On the other hand, the crustal regions prepared for an earthquake release radioactive elements such as radon (222Rn), and their decay produces radicals in the air. Be that as it may, the final result is a thermodynamically unstable state, favoring a process of phase change due to nucleation of water and the formation of aerosols, impacting significantly the psychrometry of the a releasing latent heat in the process according to the models of free energy [Dey and Singh, 2003;Saradjian and Akhoondzadeh, 2011;Zhang et al, 2013] and generating convective processes in the troposphere. The thermal flux results in temperature rising, a drop in the humidity and pressure, and finally, changes in the velocity line when jet-stream passes through the region over the future epicenter [Ouzounov et al, 2010;Pulinets and Ouzounov, 2011].…”