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The Great Wall of Bohol: Earthquake changes face of land
By KIM LUCES, GMA News
What once was a gently sloping area in Barangay Anonang, Inabanga, is now a 10-foot-high wall stretching some three kilometers across the remote town.
The jutting land features are likely the result of a newfound fault under Bohol Island which scientists are now struggling to map and understand—even as Boholanos are looking to turn the tragic aftermath into a tourist attraction.
The earthen wall could be as long as 80-100 kilometers, according to initial scientific estimates, and could extend to the sea.
The earthen wall could be as long as 80-100 kilometers, according to initial scientific estimates, and could extend to the sea.
In the wake of the magnitude 7.2 earthquake that shook Bohol, most of the local government's (LGU's) efforts have been focused on relief and shelter. But among the LGU's plans is to make the best of what they have, by turning the damaged asites into places for geological study and maybe even for tourism.
Turning disaster into opportunity
Turning disaster into opportunity
“We plan to capture the tourism component and the geological and geo-science opportunities of the new formations as a result of the earthquake,” said Bohol Governor Edgar M. Chatto in a phone interview with GMA News Online, Tuesday.
These tourist sites might include the three-kilometer rupture in Barangay Anonang, and some of the collapsed Chocolate Hills.
Phivolcs scientists are still learning about the newly discovered fault under Bohol Island. Officially named the North Bohol Fault, it is still in the process of settling: aftershocks continue to be felt and the changes it effected across the provincial landscape are still revealing themselves.
When a reverse fault like the North Bohol Fault moves, both sides of the fault compress, causing one side to move up—a phenomenon called "reverse thrust motion."
This phenomenon last happened in the Philippines in the 1970s, according to Philippine Institute of Volcanology and Seismology Director Renato Solidum, Jr.
Strong earthquakes like the 7.2-magnitude earthquake that hit Bohol sometimes cause ruptures in the surface. These ruptures are clearly evident in Barangay Anonang in Inabanga, leading experts to initially recommend naming the fault after the town.
However, as the extent of the fault came to light, experts agreed to name it the North Bohol Fault.
“Displacement of originally gently sloping to flat ground formed a northeast- to southwest-trending wall as much as 3 meters high and extends more than five kilometers long,” said the official Project NOAH blog post about the Visayas quake.
“Displacement of originally gently sloping to flat ground formed a northeast- to southwest-trending wall as much as 3 meters high and extends more than five kilometers long,” said the official Project NOAH blog post about the Visayas quake.
“The length measurement of the raised wall due to reverse faulting is currently being determined in the field and through lineament mapping using high-resolution imagery,” the blog entry said. The "wall" could be as long as 80-100 kilometers, according to initial scientific estimates, and could extend to the sea.
In 2012, a 6.9-magnitude earthquake in an unmapped thrust fault struck Negros Island but there were no physical side effects except for uplifted ridges, Solidum said.
Aside from the ruptures, the moving of the fault caused the high-tide mark in Maribojoc to move farther from the original coastline, according to the Phivolcs report summary. — TJD/HS, GMA News
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