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Author Topic: No alarm on sinkholes  (Read 535 times)

hubag bohol

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No alarm on sinkholes
« on: November 05, 2013, 08:42:14 PM »
http://boholchronicle.com.ph/





A famous historian, author, and engineer has downplayed people's fears over the presence of some 100 sinkholes in the province and in the city, saying there is nothing to worry about the sinkhole mania that puts residence at the edge of their seats.

Engineer Jes Tirol, when asked by the Chronicle whether people should go gaga over sinkholes and how they should deal with their jittery emotions, replied: “Nothing to worry. The MGB (Mines and Geosciences Bureau) report is lacking. It did not consider that limestone also becomes marble.”
...than to speak out and remove all doubt." - Abraham Lincoln


hubag bohol

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Re: No alarm on sinkholes
« Reply #1 on: November 05, 2013, 08:43:21 PM »
Pressed to comment whether he supports the planned evacuation of some 200 families living in five puroks in Poblacion Uno who may be in danger of being swallowed by sinkholes, also called by other experts as underground caves, Tirol answered: “Only for the houses over the crack.”

Asked further if he has any advisory to those who are worried of their safety, their homes, and property, Tirol replied: “Ang advise maggikan ra sa mga alagad sa gobyerno. Ang ako opinion o panahom lang.”

In 1998, Engineer Jes Tirol became a voice in the wilderness incessantly urging church and government officials to undertake a retrofitting project on Bohol's centuries-old churches so that these structures of national heritage could withstand earthquakes.

But his calls fell on deaf ears. Tirol, writing in his weekly column in the Bohol Chronicle, lamented that church officials instead of undertaking massive retrofitting of church buildings they became engrossed with “beautification.”
...than to speak out and remove all doubt." - Abraham Lincoln

hubag bohol

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Re: No alarm on sinkholes
« Reply #2 on: November 05, 2013, 08:44:05 PM »
Long before the Oct. 15 earthquake that struck Bohol and killed 209 persons while leaving more than 650 injured, Tirol had once predicted that a strong earthquake, such as has not been experienced before, could happen in Bohol after 2006 or 100 years after a strong quake hit here a century ago.

“I do not blame anyone for not listening to my warnings.  My warnings were too far ahead.  I begun my warnings in 1998 and keep on repeating until I became like a broken phonograph record.  When I made a warning of the return of the 1906 Tagbilaran earthquake for the 100 years cycle (for 2006), the Late (City) Vice-Mayor Rizalino Israel challenged me to stand at the shorelines of Taloto to see the “tsunami”.  I could not explain why the earthquake actually returned seven years late,” Tirol wrote in his weekly column.

Meanwhile, MGB officials have recommended that five puroks in Poblacion Uno are marked unsafe due to geological disturbances following the Oct. 15 earthquake.

A forced evacuation plan is eyed for some 20 families, out of the affected 200 families, whose houses are situated in the “very high risk” area of Poblacion Uno .

But certain residents opposed the evacuation plan, saying they would rather perish in the very place they can call their own rather than living in an inconvenient evacuation site.
...than to speak out and remove all doubt." - Abraham Lincoln

hubag bohol

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Re: No alarm on sinkholes
« Reply #3 on: November 05, 2013, 08:44:34 PM »
Other residents have also questioned the ground-penetrating-scanning (GPS) conducted by MGB on Poblacion Uno.

Doris D. Tan, a Boholana who is convinced of the looming danger in said place, wrote: “If there is a gaping sinkhole in the midst or very near my home and a report has been released by the authorities that this opening is an entrance of not just a single cave but a honeycombed caves, would I still wait for my government to tell me what to do?”

“It is the same way that during an earthquake and even at its aftermath, people refuse to go back to their houses and opt to live in tents for fear that the next aftershock will bring their houses down on them. And nobody ordered them to do that. It is the instinct of self preservation. So, if there is a great probability that the ground under my feet will at anytime give in, what do you think will I do?”

Sinkholes, according to Britannica Encyclopedia, is defined as a “topographic depression formed as underlying limestone bedrock is dissolved by groundwater. It is considered the most fundamental structure of karst topography.”

“Sinkholes vary greatly in area and depth and may be very large. There are two main varieties, one caused by the collapse of the roof of a cavern, the other by the gradual dissolving of rock under a soil mantle. Collapsed sinkholes generally have steep rock sides and may receive streams that then flow underground. The soil-mantled sinkhole is generally shallower than the collapsed sinkhole and receives local drainage; it may become clogged with clay and hold a small lake. Some sinkholes, formed at low sea-level stages during the Pleistocene epoch, are now half-drowned and are known as cenotes,” the resource book said. (MIKE ORTEGA LIGALIG)
...than to speak out and remove all doubt." - Abraham Lincoln

islander

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Re: No alarm on sinkholes
« Reply #4 on: November 05, 2013, 09:17:35 PM »
http://boholchronicle.com.ph/



Engineer Jes Tirol, when asked by the Chronicle whether people should go gaga over sinkholes and how they should deal with their jittery emotions, replied: “Nothing to worry. The MGB (Mines and Geosciences Bureau) report is lacking. It did not consider that limestone also becomes marble.”

interesting. 
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islander

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Re: No alarm on sinkholes
« Reply #5 on: November 05, 2013, 09:46:20 PM »
Why does limestone change into marble?

High heat and pressure cause the calcite in the limestone to recrystallize into larger crystal structures.

But...

Coastal limestones are often eroded by organisms which bore into the rock by various means. This process is known as bioerosion. It is most common in the tropics, and it is known throughout the fossil record (see Taylor and Wilson, 2003). -http://www.ask.com/
Republic Act 8485 (Animal Welfare Act of 1998, Philippines), as amended and strengthened by House  Bill 6893 of 2013--- violation means a maximum of P250,000 fine with a corresponding three-year jail term and a minimum of P30,000 fine and six months imprisonment

islander

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Re: No alarm on sinkholes
« Reply #6 on: November 05, 2013, 09:46:55 PM »
How do you recognize limestone and marble?

The main difference between limestone and marble is that limestone is a sedimentary rock, typically composed of calcium carbonate fossils, and marble is a metamorphic rock. Limestone forms when shells, sand, and mud are deposited at the bottom of oceans and lakes and over time solidify into rock. Marble forms when sedimentary limestone is heated and squeezed by natural rock-forming processes so that the grains recrystallize. If you look closely at a limestone, you can usually see fossil fragments (for example, bits of shell) held together by a calcite matrix. Limestone is more porous than marble, because there are small openings between the fossil fragments. Marble is usually light colored and is composed of crystals of calcite locked together like pieces of a jigsaw puzzle. Marble may contain colored streaks that are inclusions of non-calcite minerals.


Limestone    
Limestone is made of fossil fragments, held together with calcite; the shell near the center is about 1 cm across. Botanic Gardens building Washington, D.C.    


Marble
Marble is made of calcite crystals (white) and some colored grains of mica inclusions; the grains in a marble are locked together like jigsaw puzzle pieces.


http://pubs.usgs.gov/
Republic Act 8485 (Animal Welfare Act of 1998, Philippines), as amended and strengthened by House  Bill 6893 of 2013--- violation means a maximum of P250,000 fine with a corresponding three-year jail term and a minimum of P30,000 fine and six months imprisonment

hubag bohol

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Re: No alarm on sinkholes
« Reply #7 on: November 06, 2013, 05:13:41 AM »
He he, basin borit characterized by high heat and pressure, pwede na...

:P
...than to speak out and remove all doubt." - Abraham Lincoln

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