Tuesday, May 09, 2006

Earthquakes cause of Sea surface temperature rise.

A joint US-Indian team of researchers analysed satellite data on ocean coastal areas lying near the epicentres of four recent quakes. A published paper in the in the journal Advances in Space Research links the rise in chlrophyllic plankton prior to the recent earthquakes . In this paper, they have analyzed remote sensing data of the ocean coasts lying near the epicenters of recent four major earthquakes (Gujarat of January 26, 2001, Andaman of September 13, 2002, Algeria of May 21, 2002 and Bam, Iran earthquake of December 26, 2003).

The increase of Chl-a concentration is due to the change in sea surface temperature (SST) associated with the changes in stress regime in the epicentral region which is responsible for modifying the in situ thermal structure of the water and enhancing the upwelling of nutrient-rich water. Using satellite images and measurements of sea temperatures, they found a correlation between peaks in chlorophyll and proximity to an impending earthquake.

The increase of Chl-a concentration also shows one to one relation with the increase of surface latent heat flux (SLHF) which is found to increase significantly prior to the earthquake events.

In the late 1960s and early 1970s reports primarily from Russia and China indicated that concentrations of radon gas in the earth apparently changed prior to the occurrences of nearby earthquakes (Lomnitz, 1994). This stimulated a number of experiments in other parts of the world to monitor underground radon with time and to look for radon changes associated with earthquakes. Since radon is a radioactive gas, it is easy and relatively to monitor instrumentally, and its short half-life (3.8 days) means that short-term changes in the radon concentrations in the earth can be monitored with very good time resolution. While other gases have also been looked at as possible earthquake precursors, the bulk of the experiments reported in the scientific literature have focused on radon.

In our literature survey, we found reports of 159 observations of changes in gas emissions from 107 earthquakes. Of these, there were 125 radon observations from 86 earthquakes, 7 observations of hydrogen gas from 7 earthquakes, 7 observations of helium gas from 7 earthquakes, 10 observations of helium/argon gas ratios from 10 earthquakes, 4 observations of methane/argon ratios from 4 earthquakes, 3 observations of nitrogen/argon ratios from 3 earthquakes, 2 observations of chlorine ions from 2 earthquakes, and 1 observation of mercury gas from 1 earthquake. There are also reports of changes in the emission of other gases, such as carbon monoxide and carbon dioxide, from the earth associated with earthquakes.

some general statements can be made about the observational data for these other gases. First, for the other gases the distribution of reported anomaly amplitudes, time durations, time of initiation before the event, and distance to the epicenter appear in all cases to be similar to the observations for radon gas. The amplitudes of the anomalies seem to vary from gas to gas, with the largest reported increase being 100,000% for an observation of H2 prior to an earthquake. This would seem to suggest that other gases besides radon may give higher amplitude gas emissions prior to earthquakes if they were widely monitored.


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