Haiti’s Fault Rupture Boosts Long-Term Risk of Jamaica Quake

[FarCenter]

http://www.bloomberg.com/apps/news?pid=20601124&sid=aFUj1y6PA1Pk
By Tom Randall and Meg Tirrell

Jan. 15 (Bloomberg) -- The magnitude 7 earthquake that killed as many as 100,000 people in Haiti this week may increase the likelihood of a future quake in Jamaica, according to seismologists who study geologic risk.

When aftershocks subside in the coming weeks, Haiti’s prospects of another earthquake will plummet, while areas west along the same fault line will see increased seismic pressure, said Stuart Sipkin, a seismologist at the U.S. Geological Survey in Golden, Colorado. It could take decades or a century for the pressure to rupture on the western edge of the fault in Jamaica.

A similar quake flattened the Haitian capital of Port-au- Prince 240 years ago, so long ago that most residents were unaware they were at risk, said Roger Musson, who advises engineers on regional dangers for the British Geological Survey. The 1770 upheaval was part of a string of westward-moving temblors that culminated in Jamaica in 1907, he said.

“In Haiti, there’s not been earthquakes in living memory; now it’s likely that the stress will be increased on the next segment along,” Musson, the agency’s head of seismic hazard, said in a telephone interview. However, he added, “You are constantly surprised by earthquakes doing things that they’re not supposed to do.”

Haiti lies near the eastern end of a fault line between the North American and Caribbean tectonic plates -- massive subterranean sections of the earth’s crust that move at about the speed that human fingernails grow, Sipkin said.

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[HipChick]

1. St Martinique had a 7.4 quake 2yrs ago..

but it was 90 miles down...

[FarCenter]

3. St Martinique is west of the subduction zone

The Lesser Antillies are the result of the South American plate burying itself under the Carribean plate. Hence earthquakes and volcanos along the eastern edge of the Carribean. But an earthquake in that area would also be deep.

The fault that caused the Haitian earthquake is on a strike/slip zone where the Carribean Plate is moving west at a slower speed than the adjacent North American plate.

[GreenPartyVoter]

2. Oh no!

[malaise]

4. Yep we know we're vulnerable

Yesterday was the 103rd anniversary of the great Kingston Earthquake.

The worst earthquake in our history was the 1692 Port Royal earthquake. Part of the city of Port Royal is still under the water.

We have annual reminders here, but if we were hit with a 7 like Haiti in Kingston, the loss of life would be similar.

[haele]

5. USGS site has a description of the great Port Royal earthquake of 1692

http://earthquake.usgs.gov/earthquakes/world/events/1692_06_07.php

Killed over 5000 people (out of an entire affected area that probably only had an estimated 6500 - 10000 people), destroyed over 90% of Port Royal.
1.8 miles of city "slipped under the water"; whether from a tidal wave from a sheer off of the hills around the harbor, or from the quake itself. The estimated magnitude is not known as the epicenter was shallow and apparently within a mile or two of the harbor, but I've read previously that it could have been anywhere from 6.8 (epicenter within in the contemporary harbor under the wharfs) or 7.5 (epicenter up to 5 miles out past the mouth of the harbor)

A Texas A&M site that does arechological research out of Port Royal has a map of the original port outline superemposed on a current map.
http://nautarch.tamu.edu/portroyal/archhist.htm

Haele