DRRR M5 DRRR(Sinkhole Hazards) PDF

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Philosopy about Man and Freedom of St. Thomas...

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Written by BEVERLY S. BARRO, LPT

DOMINICAN BLESSING May God the father bless us. May God the son heal us. May God the holy spirit enlighten us, And give us Eyes to see with, Ears to hear with, Hands to do the work of God with, Feet to walk with, A mouth to preach the word of salvation with, And the angel of peace to watch over us and lead us at last, By our lord's gift, to the kingdom. Amen.

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GENERAL INSTRUCTIONS

This module is designed for the new set-up of education in the new normal—distance learning. There are different types of modalities to deliver instruction presented in this module (electronic-online, electronic– offline, and printed). We understand the limitations that this pandemic have brought to us so for this subject, you are free to choose the modality that suits your present situation.

In general, take note of the following: 1. Ask for God’s guidance as you work through this module. The Dominican blessing is at the first page of this module. 2. Read this module. Unlike before, your teachers are not there to discuss the topics presented. Be responsible of your own learning since it is at your own pace. 3. Explore from different sources. As a STEM student and soon-to-be-researcher taking up this subject, you are encouraged to go beyond what is given in this module. 4. Perform the activities presented. You will be required to submit the activities for a given period of time. 5. Ask your teachers for clarifications if there are any. 6. Take care of your health. Please make sure that as you work on this requirem ill not compromise your physical, emotional and mental health.

On Submissions via Phoenix Aralinks

 Module will be uploaded on Aralinks depending upon the allotted time prescribed by the DepEd’s Most Essential Learning Competencies (MELCS).  Activities will be posted on Aralinks together with the answer sheet.  Answer sheets must ALWAYS be converted into pdf file and submitted on your individual e-portfolio following the file name format, Surname_Module no. Title of the activity

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COURSE/SUBJECT: Disaster Readiness and Risk Reduction 11 MODULE TITLE: Sinkholes Preparedness WRITER: BEVERLY S. BARRO, LPT TOPIC: Sinkholes in the Philippine Setting

Module Introduction and Guide Questions Philippines having karst topography and numerous bodies of water is also prone to sinkhole formation. Sinkholes develop gradually oftentimes contributed by excessive extraction of the ground water until such time it is empty without anything holding the ground. As you go on with this module, you will shall be able to answer the ff. guide questions: 1. 2. 3. 4. 5.

What are the major causes of sinkholes in the Philippines? How are sinkholes formed? What are the different types of sinkholes? How can you recognize impending signs of sinkholes? What are the precautionary measures you need to in a sinkhole collapse?

Subtopic

Lesson Objectives

Time

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Introduction to sinkholes

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Define what is a sinkhole Identify causes sinkhole formation

1 hr.

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Types of sinkholes

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Cite different types of sinkholes Recognize impending signs of sinkhole collapse

1.5 hrs.

Cite the precautionary measures before, during and after a sinkhole collapse

1.5 hrs.

• •

Sinkholes Preparedness

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Objectio Sinkhole is a natural depression or hole in the surface topography caused by the karst processes or chemical dissolution of carbonate rocks (limestone and dolomite), salt beds, or rocks (salt, gypsum, and anhydrite) that can naturally be dissolved by groundwater circulating through them. GENERAL CHARACTERISTICS OF SINKHOLES • can vary from a few feet to hundreds of acres and from less than 1 to more than 100 feet deep. • some are shaped like shallow bowls or saucers whereas others have vertical walls; some hold water and form natural ponds. • they form so slowly that little change is noticeable, but they can form suddenly when a collapse occurs. Such a collapse can have a dramatic effect if it occurs in an urban setting.

Types of Sinkholes 1. Dissolution sinkholes - occur where there is little soil or vegetation over the soluble rock. - aggressive dissolution occurs where flow is focused in pre-existing openings in the rock , such as along joints, fractures, and bedding planes, or in the zone of water – table fluctuations where the ground water is in contact with the rock surface.

2. Cover-subsidence sinkholes - tend to develop gradually where the covering sediments are permeable and contain sand.

3. Cover-collapse sinkholes. tend to develop abruptly and cause catastrophic damages. occur where the covering sediments contain significant amounts of clay.

Human Activities that Trigger the Formation of Sinkholes • Over-withdrawal of groundwater • Diverting surface water from a large area and concentrating it in a single point

• Artificially creating ponds of surface water • Drilling new water wells

Various Causes of Sinkholes 1.

Water a. Weathering: If the rocks below the surface are made of materials that dissolve in water like limestone and gypsum, the water dissolves these minerals and opens spaces within the rock.

b. If the rock does not dissolve in water: This occurs when the rock under the surface doesn’t dissolve in water but instead is made of grains that are small enough to be carried away by underground water currents, resulting in sinkholes.

The sinkhole appeared Sunday in downtown Guatemala City, swallowing a three-story building. PHOTOGRAPH BY MOISES CASTILLO, AP

c. Surface-water: This third situation has nothing to do with underground water currents, but rather is all about water movements above-ground. They are triggered by intense rainstorms or floods and burst or long-term leakage from a sewer or storm-water pipes. If these currents are too strong, the water will not go where it is used to but rather, will find new paths. If it travels on a surface without ample support from below ground, it will result in sinkholes. Additionally, the water may settle in one location, causing the surface to become impermeable with water but as it leaks into the ground, it will result in sinkholes.

d. Weather changes: Sinkholes can also result from seasonal changes in the groundwater table, freeze and thaw of the ground and extreme precipitation, showcased when there are heavy rains following droughts.

e. Changes in the hydrologic system: Sudden changes to the hydrologic system, such as putting more water in or taking it out, can cause systems to become temporarily unstable, resulting in sinkholes f. Changing groundwater gradients: If there is a change in the groundwater gradients, mainly due to the removal or introduction of water to these systems, loose materials can flush out quicker than usual, causing voids, which result in the collapse of the surface 2. Human Activities Some human activities are resulting in more sinkholes today. For instance, forming from abandoned mines. Sinkholes can be a result of many underground voids and drainage systems carved from the carbonate rocks throughout the state. If these overlaying layers of ground collapse into these voids, a sinkhole is born. Also, drainage systems may break and drain water into these rocks that are weak against such waters. The result will be a sinkhole.

3. Earthquake-induced sinkholes Earthquakes are a natural occurrence, which might result in sinkholes, assuming they hit areas with a weak rock below the surface. However, there are increased induced earthquakes, which are as a result of both industrial and human activities, which also causes sinkholes. Careless mining and hydraulic fracking can impact an area especially its stability as well as water quality, resulting in earthquakes that result in a sinkhole.

Warning Signs of Sinkholes • Gradual localized ground settlement • Doors and windows fail to close properly • Cracks in a foundation • A circular pattern of ground cracks outlining the sinking area

• Vegetation stress due to a lowered water table • Turbidity in local well water due to sediment washing into the limestone’s pores Effects of Sinkholes

• they can change the general topography of the area and divert streams of underground water. • they can cause a lot of damage to human life and property. • can be dangerous to the foundations of the building. • toxic chemicals beneath the earth can come up and may pollute the groundwater.

Karst Topography Mapping • Choose a setting near your place, at least 3-5 kilometers (either a hill, plain, plateau, valley, cliff etc.) • Observe the topography of your chosen area. • Using legends, map its topography. Indicate if you found none karst topography. • Look at the example at the right side of this page.

Sinkholes in the Philippines

1. Sinkhole in Bantayan Island and Badian, Cebu

Another sinkhole in Sta. Fe town in Bantayan island was found in July a year ago that constrained families in sitio Dapdap, Barangay Langub to move. At first, the opening is a few feet wide yet developed more extensive as per occupants. The sinkhole was around 40 feet wide and 4 feet profound.

Reports said the sinkhole in Badian town keeps on developing more extensive. When it was found toward the end of last year, it was just five meters wide and 10 meters profound. Geologists said could be ascribed to the drawn out and exceptional downpours and tremor.

2. Sinkhole in Kabankalan City, Negros Occidental Six individuals have allegedly fallen into a 12 feet profound sinkhole that all of a sudden showed up amidst a ball court in Purok Jalandoni, Barangay Oringao in Kabankalan City, Negros Occidental in July lasy year. MGB said the gap might have been made by water streaming underground. Theu considered this as a topographical danger.

3. Baguio City sinkholes

Sinkholes are very basic in Baguio City, which additionally has no less than seven known issues and various zones helpless against avalanches. Avalanches could be activated by a tremor or constant precipitation, which can likewise make sinkholes wreak devastation.

4. Sinkhole in Bohol

The profound opening found in Barangay Cambilan, Catigbian, Bohol as indicated by Harlans Multimedia Production who has posted the video in Youtube said it was because of the 7.2 size quake that struck the territory in October 2013.

5. Strange Underwater sinkhole of Dadiangas, GenSan

Debacle authorities are still confounded on a profound opening suspected sinkhole at Purok Tinago, a group of casual pilgrims in Barangay South Dadiangas, General Santos City. Neighborhood TV stations have reported that it abruptly showed up in February this year.

PRECAUTIONARY MEASURES SINKHOLES If you are in a public area: • Evacuate immediately • Do not get too close to the sinkhole • Call emergency services if the hole is large and a risk to others • Raise awareness of other members of the public and ensure that others do not enter the area of and around the sinkhole If you are in a residential area • Evacuate immediately • Under no circumstances enter your house again if structures are at risk of collapse • Do not get too close to the sinkhole • Call emergency services if the hole is large and a risk yourself or/and to others • Raise awareness of neighbors and other residents which could be at risk • Watch out for surface cracks and stay back

MITIGATING SINKHOLES

If you are a resident and you want to take actions for mitigation you can do the following: • • • • •

Check your home and property for: Cracks in the exterior and interior walls of your home Sloping and unevenness of the floors in your home Muddy or clouded water in your toilette, shower and tap Cracks (especially in circular shape) around your property

Lesson Objectives

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•

•

•

Easy, I get it!

I understand, but more examples please!

Help, I don’t understand anything!

Define what is a sinkhole Identify causes sinkhole formation Cite different types of sinkholes Recognize impending signs of sinkhole collapse Cite the precautionary measures before, during and after a sinkhole collapse

References:

Luna E.M. Protecting Lives, Saving Communities; DRRR in Philippine Setting for Senior High School.Quezon City: C&E Publishing House

Amadore, L.A., Valenzuela, R.G.(2017).Disaster Risk Reduction for the Youth; Science-based Disaster Readiness and Risk Reduction.Makati City: Salesiana Books by Don Bosco Press Inc.

Lanada M.I., Melegrito M.L, Mendoza, D.J. (2018). Building Resilent Communities; Disaster Readiness and Risk Reduction. Quezon City: Phoenix Publishing House https://www.livescience.com/44123-what-are-sinkholes.html https://www.dep.pa.gov/Citizens/My-Water/Sinkholes/Pages/What-causes-a-sinkhole.aspx https://www.nationalgeographic.com/environment/sinkhole/

https://www.theguardian.com/environment/2014/feb/20/are-humans-causing-more-sinkholes...