Saturday, January 31, 2009

Feb. 9 Penumbral Lunar Eclipse prompts Spring Tide alert for Sumatra

They still have not arrived at a definitive count of the dead from the Boxing Day earthquake and tidal wave of December 26, 2004 in Banda Ache, the semi-autonomous province on the northern-most part of Sumatra in the Indonesian archipelago.

Observational evidence does not show any direct link between the tidal forces of the Earth-Moon system on tectonics or earthquake activity, though the barycenter of the Earth-Moon system is not at the center of Earth or in Space between the two bodies but rolls along roughly one third of the way from the outer crust to Earth's core. There's plenty of magma, essentially a liquid with far more density and, therefore, inertia than the saltwater covering the outer 70 percent of our planet.

On the disaster-created islands of greater Indonesia, however, hundreds of millions live with daily reminders of the dynamic nature of the Earth's outer layer.

Tidal lock holds the heavier Near Side of our Moon facing Earth and the Moon pulls back, constantly, most directly seen in the tides.

Tomorrow's Jakarta Post echoes warnings from the West Sumatra Natural Disaster Coordinating Unit to "fishermen and sea travel operators" that "the Lunar Eclipse of February 9 could summon violent waves up to five meters high. Unit head Ade Edward said Saturday that the gravitational effect of the eclipse would be accompanied by strong wind from the Indian Ocean heading towards seashores in Sumatra, creating beach abrasion and flood. “We have issued warnings for violent waves, flood, landslide and abrasion to all regency and cities in West Sumatra, so that they will be prepared for the extreme weather conditions which will peak in February,” Ade said. He also said fishermen were urged to watch over the sky before going to the sea, “if the clouds are dark, they better not go to sea."

The February 9 Lunar Eclipse will be prenumbral, meaning the Moon will only skirt Earth's shadow at the extreme southern edge, just before astronomical Full Moon. Unlike the Annual Solar Eclipse in January or the Total Eclipse of July 22, visible in Indonesia as respectable annular and partial eclipses of the Sun in the same area of the Far East, the February 9 "eclipse" barely rates a mention.

The combination of Moon and Sun overhead should cause a strong Spring Tide, heaping up waters largely during the time immediately after the Moon skirts Earth's shadow.

And, as Ade warns, the same effects should occur the day before and after, without much noticable difference, so his warning is accurate up to that point.

But what about those strong winds, landslides and the dark clouds being signs to stay ashore?

Perhaps there is some effect upon a heaping Indian Ocean on the sea breezes during February's Spring Tides near the equator, but I doubt it.

Landslides? Not unless you think erosion by high tides might be in store, again near the shore.

And "Dark clouds?"

Whether or not there are Dark Clouds in the sky, a Spring Tide in February is going to occur, and if you were a fisherman or a coastal dweller, still a little shell-shocked from the tidal wave and massive earthquake of late 2004, dark clouds are not going to mean that the Spring Tide in February will be any better or worse.

Perhaps this report loses something in the translation from Malay into English, but perhaps authorities would prefer the Sumatrans stay ashore, in and around February 9.

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