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Seismic News
Chile, S.A.

April, 2007
Chile’s Region XI, an area also known as Aysén, has been rocked by an ongoing wave of seismic activity (more than 4,200 tremors) that began in late January and shows no sign of letting up. Early Thursday morning (4/5), residents in Puerto Chacabuco and Puerto Aysén – the two towns most affected by the recent phenomenon – were startled by three back-to-back-to-back tremors that registered 3, 4 and 3 on the Mercalli scale respectively. Though quite minor, the tremors were nevertheless a reminder that the recent barrage of seismic activity – which began with a Jan. 23 quake that registered 5.2 on the Mercalli scale – is clearly not over yet. A much more significant tremor – the strongest to affect the area so far – struck late Sunday night (4/1), registering a formidable 5.5 on the Richter scale. The tremor was slightly stronger than a 5.2 quake that occurred on Feb. 23. “Obviously the people here feel uneasy. It’s something they’re not at all accustomed to. That’s basically the problem. It’s been so unpredictable, you don’t know when they’ll happen, and the waiting and waiting – obviously that creates some nervousness.” When the quakes first began, locals feared a pending volcanic eruption of nearby Hudson Volcano, which last erupted on August 8, 1991. That eruption, the second largest recorded in Chile, was preceded by a similar cluster of tremors and earthquakes. Authorities, however, have since come up with another theory to explain the tremors. A team of scientists dispatched to the area in late January concluded that the quakes are likely being caused by an underground magma flow, located below the floor of the nearby Aysén fjord. The magma, which is pressuring a subterranean tectonic plate, could eventually push its way to the surface and form a relatively small volcanic cone on the floor of the fjord. Concerned residents and environmentalists have pointed out that the site of a proposed US$600 million, 600 MW dam is dangerously close to the epicenter of the recent quakes.
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