Wednesday, March 21, 2018

Exploring Taal Volcano

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LDRRMOs in Taal Volcano

DRRMOs in Taal 2018On February 22, 2018 Local DRRM Officers from the Batangas Province went to Taal Volcano as part of their continuing learning on what to do in case the historic volcano erupts again.  The LDRRMOs were led by PDRRM Officer; Mr. Joselito M. Castro and they were joined by officers and employees from the Philippine Volcanology and Seismology (PhiVolcs) who gave lectures on their activities to monitor Taal Volcano.

The visiting team used the Sea Ambulances earlier issued by Governor Hermilando I. Mandanas through the  Provincial Disaster Risk Reduction and Management Council (PDRRMC) and detailed to municipalaities along the Taal Lake.  Joining the LDRRMOs are officers and staff from the Batangas Provincial Disaster Risk Reduction and Management Office (PDRRMO).

4th Quarter Council Meeting

4th Quarter Council meeting 2017The Joint Meeting of the Provincial Peace and Order Council, Provincial Disaster Risk Reduction and Management Council, Provincial Development Council and Provincial Association of Barangay Captains was held on October 26, 2017 and presided over by Governor Hermilando I. Mandanas.

The joint meeting was attended by members of the Sangguniang Panlalawigan headed by Vice Governor Sofronio Ona, local chief executives, local disaster risk reduction and management officers, members of the PDRRM Council and other functionaries of the provincial government.

PDRRMO Staff Returned Two Cellphones

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Batangas City.  Two (2) units of cellular phones (Lenovo and Oppo) were found by a PDRRMO Operations Staff; Mr. Roger Galfo inside a bus as he departed from the same at the Batangas Grand Terminal on October 13, 2017.

Being a good and honest man, he kept the cellphones on, hoping to recieve a call from its owner.  On October 16, he recieved a call from the owner; Mr. Oliver who was taking up Master's Degree at the University of Santo Tomas, Manila.  On that same day, the owner with his mother, arranged to meet Mr. Galfo and arrived at the PDRRM Office at the Provincial Sports Complex in Brgy. Bolbok, this city.  Mr. Oliver was so delighted and happy to have found his lost cellphones and thanked Mr. Galfo for his honesty and dedication to be of service to the people.

Mr. Galfo, a former fire volunteer at the Valenzuela Fire District has been in the line of rescue volunteer and is currently among the finest rescue / disaster responders of the Batangas Provincial Disaster Risk Reductio and Management Office since last year.

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Role of Media in Disaster Management

Batangas City.  The Provincial Disaster Risk Reduction and Management Office (PDRRMO) conducted a 1-day seminar workshop dubbed as the "Role of Media in Disaster Management" on December 19, 2017 at the  DepEd Conference Hall, Batangas Provincial Sports Complex in Brgy. Bolbok, this city.  

In his welcome and opening remarks, Mr. Joselito M. Castro stressed the importance of media in disaster operations not only in information dissemination, but also for the swift and orderly management of disasters.

Resource speakers for the activity were Ms. Georgina R. Garcia of the Office of Civil Defense IV-A and Mr. Antonio V. de Lacy, Jr. of the Provincial Disaster Risk Reduction and Management Office of Batangas.

The event was participated by representatives from both print and broadcast media based in Batangas as well as personnel from the Provincial Information Office.

Batangas Local DRRMOs in Taal

2018 1st Qtr NSED in Rosario

Emergency Medical Services

Weather Forecast

Daily Weather Forecast (Southern Luzon)

Issued at:  5:00 AM today, 16 MARCH 2018

SYNOPSIS   Easterlies affecting the Country.

FORECAST:  Cloudy skies with scattered rainshowers and isolated thunderstorms will be experienced over Northern Samar. Partly cloudy to cloudy skies with isolated rainshowers will prevail over Bicol Region, Oriental Mindoro, Marinduque and Romblon. Moderate to strong winds blowing from the east to northeast with moderate to rough seas over Bicol Region and Northern Samar. Light to moderate winds blowing from the east to northeast with slight to moderate seas over Oriental Mindoro, Marinduque and Romblon.






Severe Weather Bulletin


Issued at:  4:00 AM today, 16 March 2018
SYNOPSIS:  Easterlies affecting the country.


Earthquake Bulletin

On March 16, 2018, at about 4:11 A.M., a magnitude 2.3 earthquake hit Calatagan, Batangas with the following data:

Latitude (oN):       13.63

Longtitude (oE):   120.59

Depth:                  50 KM

Epicenter:            023 km S 13° W of Calatagan (Batangas)

Another earthquake hit on the same date at about 8:10 AM with magnitude 2.1.  Data are as follows:

Latitude (oN):       13.63

Longtitude (oE):   120.64

Depth:                  19 KM

Epicenter:            023 km S 13° W of Calatagan (Batangas)







Gawad Kalasag 2017

Gawad Kalasag 2017

On August 24, 2017, the Batangas Provincial Disaster Risk Reduction and Management Council received its second Gawad Kalasag championship for the Provincial DRRM Council category.  Receiving the prestigious award were Vice Governor Sofronio Ona, PDRRM Officer Joselito M. Castro and Provincial Engineer Gilbert Gatdula.  The current imrpovements, activities and innovations undertaken by the PDRRMO and the PDRRMC under the leadership of Governor Hermilando I. Mandanas will ensure the capturing of the third Gawad Kalasag award next year that will put the Batangas PDRRMC into the pedestal of Hall of Famers for Gawad Kalasag.


OCD IV-A, Council Member Agencies Visited Taal Volcano

OCD et al in TaalMarch 13, Balete.  Officers and staff from the Office of Civil Defense IV-A and council member agencies, Batangas PDRRMO staff, together with the Batangas Provincial Disaster Risk Reduction and Management Officer; Mr. Joselito M. Castro visited the historic Taal Volcano as part of the on-going preparation for the Taal Volcano Contingency Plan.

The visiting team was welcomed by staffs from the Philippine Institute of Volcanology and Seismology (PhiVolcs) who led the Taal Volcano tour for the team and explained what PhiVolcs is doing to monitor the volcano.  The council member agencies were led by Dir. Olivia M. Luces of the Office of Civil Defense IV-A / Regional Disaster Risk Reduction and Management Council IV-A.

The team hoped to gain more information and knowledge that will be useful for the crafting of the Contingency Plan for Taal Volcano being spearheaded by the RDRRMC.  On the other hand, revisiting Taal Volcano will prove useful for the Batangas PDRRMO who at the moment is at the final stages of completing he Provincial Government's contingency plan for Taal Volcano.

2018 1st Qaurter NSED in Rosario, Batangas

2018 1stQ NSEDRosario, Batangas.  The Provincial PDRRMO conducted the 2018 1st Quarter Nationwide Simulataneous Earthquake Drill (NSED) on Thursday, February 15, 2018 at 2:00 PM in Rosario, Batangas.

The ceremonial venue chosen was at the Rosario East Central School (RECS) where more than 1,500 students, teaching and non-teaching staffs / personnel,  representatives from national government agencies like the Philippine National Police (PNP), Bureau of Fire Protection (BFP), Philippine Air Force (PAF), department heads from the local government of Rosario, Batangas, responders from MDRRMO-Rosario, MDRRMO-San Juan, Batangas PDRRMO and Kabalikat Civicom San Luis Chapter participated.

According to Mr. Joselito M. Castro, Provincial Disaster Risk Reduction and Management Officer, the conduct of earthquake drills nationwide is to educate our citizens on what to do during the occurence of earthquakes to ensure their safety, to inculcate in their minds and make these safety practices a custom for all Filipinos.

Read more: 2018 1st Qaurter NSED in Rosario, Batangas

1st Quarter BALDDRMO Meeting

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Batangas City.  The 1st quarter meeting of the Batangas Association of Local Disaster Risk Reduction and Management Officers (BALDDRMO) was held today, February 9, 2018 at the Conference Hall of the Batangas Provincial Planning and Development Office (PPDO) led by the PDRRM Officer; Mr. Joselito M. Castro.

Ms. Georgina Garcia of the Office of Civil Defense (OCD) IV-A discussed the OCD IV-A activities involving Batangas while Mr. Alex Masiglat oriented the local DRRM Officers about joining the Gawad Kalasag competition.  Mr. Castro discussed the proposed critical infrastructure projects to be undertaken by the PDRRM Council, including the dredging of Pansipit River.  He also discussed the conduct of the 1st Quarter Nationwide Simultaneous Earthquake Drill to be held on February 15.

Read more: 1st Quarter BALDDRMO Meeting

Search and Rescue Training

FEATURE:  11 Facts about Volcanoes


  1. A volcano is a mountain that opens downward to a pool of molten rock below the surface of the earth. When pressure builds up, eruptions occur.
  2. In an eruption, gases and rock shoot up through the opening and spill over or fill the air with lava fragments. Eruptions can cause lava flows, hot ash flows, mudslides, avalanches, falling ash and floods.
  3. The danger area around a volcano covers about a 20-mile radius.
  4. Fresh volcanic ash, made of pulverized rock, can be harsh, acidic, gritty, glassy and smelly. The ash can cause damage to the lungs of older people, babies and people with respiratory problems.
  5. Volcanic lightning occurs mostly within the cloud of ash during an eruption, and is created by the friction of the ash rushing to the surface. Roughly 200 accounts of this lightning have been witnessed live.
  6. An erupting volcano can trigger tsunamis, flash floods, earthquakes, mudflows and rockfalls.
  7. More than 80% of the earth's surface is volcanic in origin. The sea floor and some mountains were formed by countless volcanic eruptions. Gaseous emissions from volcano formed the earth's atmosphere.
  8. There are more than 500 active volcanoes in the world. More than half of these volcanoes are part of the "Ring of Fire," a region that encircles the Pacific Ocean.
  9. Active volcanoes in the U.S. are found mainly in Hawaii, Alaska, California, Oregon and Washington, but the greatest chance of eruptions near areas where many people live is in Hawaii and Alaska.
  10. The sound of an eruption volcano can be quiet and hissing or explosive and booming. The loud cracks travel hundreds of miles and do the most damage, including hearing loss and broken glass.
  11. The most deadly eruptions have occurred in Indonesia, with tens of thousands of lives lost to starvation, tsunami (as a result of the eruption), ash flows, and mudflows.

What Are The Benefits Of Volcanoes?

Article written: 19 March, 2016
Updated: 4 May, 2017

by Matt Williams

Volcanoes are renowned for their destructive power. In fact, there are few forces of nature that rival their sheer, awesome might, or have left as big of impact on the human psyche. Who hasn’t heard of tales of Mt. Vesuvius erupting and burying Pompeii? There’s also the Minoan Eruption, the eruption that took place in the 2nd millennium BCE on the isle of Santorini and devastated the Minoan settlement there.

In Japan, Hawaii, South American and all across the Pacific, there are countless instances of eruptions taking a terrible toll. And who can forget modern-day eruptions like Mount St. Helens? But would it surprise you to know that despite their destructive power, volcanoes actually come with their share of benefits? From enriching the soil to creating new landmasses, volcanoes are actually a productive force as well.

Soil Enrichment:

Volcanic eruptions result in ash being dispersed over wide areas around the eruption site. And depending on the chemistry of the magma from which it erupted, this ash will be contain varying amounts of soil nutrients. While the most abundant elements in magma are silica and oxygen, eruptions also result in the release of water, carbon dioxide (CO²), sulfur dioxide (SO²), hydrogen sulfide (H²S), and hydrogen chloride (HCl), amongst others.

In addition, eruptions release bits of rock such as potolivine, pyroxene, amphibole, and feldspar, which are in turn rich in iron, magnesium, and potassium. As a result, regions that have large deposits of volcanic soil (i.e. mountain slopes and valleys near eruption sites) are quite fertile. For example, most of Italy has poor soils that consist of limestone rock.

But in the regions around Naples (the site of Mt. Vesuvius), there are fertile stretches of land that were created by volcanic eruptions that took place 35,000 and 12,000 years ago. The soil in this region is rich because volcanic eruption deposits the necessary minerals, which are then weathered and broken down by rain. Once absorbed into the soil, they become a steady supply of nutrients for plant life.

Hawaii is another location where volcanism led to rich soil, which in turn allowed for the emergence of thriving agricultural communities. Between the 15th and 18th centuries on the islands of Kauai, O’ahu and Molokai, the cultivation of crops like taros and sweet potatoes allowed for the rise of powerful chiefdoms and the flowering of the culture we associate with Hawaii today.

Volcanic Land Formations:

In addition to scattering ash over large areas of land, volcanoes also push material to the surface that can result in the formation of new islands. For example, the entire Hawaiian chain of islands was created by the constant eruptions of a single volcanic hot spot. Over hundreds of thousands of years, these volcanoes breached the surface of the ocean becoming habitable islands, and rest stops during long sea journeys.

This is the case all across the Pacific, were island chains such as Micronesia, the Ryukyu Islands (between Taiwan and Japan), the Aleutian Islands (off the coast of Alaska), the Mariana Islands, and Bismark Archipelago were all formed along arcs that are parallel and close to a boundary between two converging tectonic plates.

The island of Santorini, Greece. Credit: EOS/NASA/ Public Domain

Much the same is true of the Mediterranean. Along the Hellenic Arc (in the eastern Mediterranean), volcanic eruptions led to the creation of the Ionian Islands, Cyprus and Crete. The nearby South Aegean Arc meanwhile led to the formation of Aegina, Methana, Milos, Santorini and Kolumbo, and Kos, Nisyros and Yali. And in the Caribbean, volcanic activity led to the creation of the Antilles archipelago.

Where these islands formed, unique species of plants and animals evolved into new forms on these islands, creating balanced ecosystems and leading to new levels of biodiversity.

Volcanic Minerals and Stones:

Another benefits to volcanoes are the precious gems, minerals and building materials that eruptions make available. For instance, stones like pumice volcanic ash and perlite (volcanic glass) are all mined for various commercial uses. These include acting as abrasives in soaps and household cleaners. Volcanic ash and pumice are also used as a light-weight aggregate for making cement.

The finest grades of these volcanic rocks are used in metal polishes and for woodworking. Crushed and ground pumice are also used for loose-fill insulation, filter aids, poultry litter, soil conditioner, sweeping compound, insecticide carrier, and blacktop highway dressing.

The roof of the Pantheon, as seen from nearby rooftops in Roe. Credit: Public Domain/Anthony Majanlahti

Perlite is also used as an aggregate in plaster, since it expands rapidly when heated. In precast walls, it too is used as an aggregate in concrete. Crushed basalt and diabase are also used for road metal, railroad ballast, roofing granules, or as protective arrangements for shorelines (riprap). High-density basalt and diabase aggregate are used in the concrete shields of nuclear reactors.

Hardened volcanic ash (called tuff) makes an especially strong, lightweight building material. The ancient Romans combined tuff and lime to make a strong, lightweight concrete for walls, and buildings. The roof of the Pantheon in Rome is made of this very type of concrete because it’s so lightweight.

Precious metals that are often found in volcanoes include sulfur, zinc, silver, copper, gold, and uranium. These metals have a wide range of uses in modern economies, ranging from fine metalwork, machinery and electronics to nuclear power, research and medicine. Precious stones and minerals that are found in volcanoes include opals, obsidian, fire agate, flourite, gypsum, onyx, hematite, and others.

Global Cooling:

Volcanoes also play a vital role in periodically cooling off the planet. When volcanic ash and compounds like sulfur dioxide are released into the atmosphere, it can reflect some of the Sun’s rays back into space, thereby reducing the amount of heat energy absorbed by the atmosphere. This process, known as “global dimming”, therefore has a cooling effect on the planet.

Sarychev volcano, (located in Russia’s Kuril Islands, northeast of Japan) in an early stage of eruption on June 12, 2009. Credit: NASA

The link between volcanic eruptions and global cooling has been the subject of scientific study for decades. In that time, several dips have been observed in global temperatures after large eruptions. And though most ash clouds dissipate quickly, the occasional prolonged period of cooler temperatures have been traced to particularly large eruptions.

Because of this well-established link, some scientists have recommended that sulfur dioxide and other be released into the atmosphere in order to combat global warming, a process which is known as ecological engineering.

Hot Springs and Geothermal Energy:

Another benefit of volcanism comes in the form of geothermal fields, which is an area of the Earth characterized by a relatively high heat flow. These fields, which are the result of present, or fairly recent magmatic activity, come in two forms. Low temperature fields (20-100°C) are due to hot rock below active faults, while high temperature fields (above 100°C) are associated with active volcanism.

Geothermal fields often create hot springs, geysers and boiling mud pools, which are often a popular destination for tourists. But they can also be harnessed for geothermal energy, a form of carbon-neutral power where pipes are placed in the Earth and channel steam upwards to turn turbines and generate electricity.

Steam rising from the Nesjavellir Geothermal Power Station in Iceland. Credit: Gretar Ívarsson/Fir0002

In countries like Kenya, Iceland, New Zealand, the Phillipines, Costa Rica and El Salvador, geothermal power is responsible for providing a significant portion of the country’s power supply – ranging from 14% in Costa Rica to 51% in Kenya. In all cases, this is due to the countries being in and around active volcanic regions that allow for the presence of abundant geothermal fields.

Outgassing and Atmospheric Formation:

But by far, the most beneficial aspect of volcanoes is the role they play in the formation of a planet’s atmosphere. In short, Earth’s atmosphere began to form after its formation 4.6 billion eyars ago, when volcanic outgassing led to the creation of gases stored in the Earth’s interior to collect around the surface of the planet. Initially, this atmosphere consisted of hydrogen sulfide, methane, and 10 to 200 times as much carbon dioxide as today’s atmosphere.

After about half a billion years, Earth’s surface cooled and solidified enough for water to collect on it. At this point, the atmosphere shifted to one composed of water vapor, carbon dioxide and ammonia (NH³). Much of the carbon dioxide dissolved into the oceans, where cyanobacteria developed to consume it and release oxygen as a byproduct. Meanwhile, the ammonia began to be broken down by photolysis, releasing the hydrogen into space and leaving the nitrogen behind.

Another key role played by volcanism occurred 2.5 billion years ago, during the boundary between the Archaean and Proterozoic Eras. It was at this point that oxygen began to appear in our oxygen due to photosynthesis – which is referred to as the “Great Oxidation Event”. However, according to recent geological studies, biomarkers indicate that oxygen-producing cyanobacteria were releasing oxygen at the same levels there are today. In short, the oxygen being produced had to be going somewhere for it not to appear in the atmosphere.

Roughly 2.5 billion years ago, towards the end of the Archaean Era, oxidation of our atmosphere began. Credit:

The lack of terrestrial volcanoes is believed to be responsible. During the Archaean Era, there were only submarine volcanoes, which had the effect of scrubbing oxygen from the atmosphere, binding it into oxygen containing minerals. By the Archaean/Proterozoic boundary, stabilized continental land masses arose, leading to terrestrial volcanoes. From this point onward, markers show that oxygen began appearing in the atmosphere.

Volcanism also plays a vital role in the atmospheres of other planets. Mercury’s thin exosphere of hydrogen, helium, oxygen, sodium, calcium, potassium and water vapor is due in part of volcanism, which periodically replenishes it. Venus’ incredibly dense atmosphere is also believed to be periodically replenished by volcanoes on its surface.

And Io, Jupiter’s volcanically active moon, has an extremely tenuous atmosphere of sulfur dioxide (SO²), sulfur monoxide (SO), sodium chloride (NaCl), sulfur monoxide (SO), atomic sulfur (S) and oxygen (O). All of these gases are provided and replenished by the many hundreds of volcanoes situated across the moon’s surface.

As you can see, volcanoes are actually a pretty creative force when all is said and done. In fact, as terrestrial organisms depend on them for everything from the air we breathe, to the rich soil that produces our food, to the geological activity that gives rise to terrestrial renewal and biological diversity.

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Hazardous Volcanic Events

There are several kinds of events caused from volcanic action that can be harmful to life and property. These include lava flows, lahars, ash falls, debris avalanches, and pyroclastic density currents.

Pyroclastic Density Currents

Pyroclastic density currents are are gravity-driven, rapidly moving, ground-hugging mixtures of rock fragments and hot gases. This mixture forms a dense fluid that moves along the ground with an upper part that is less dense as particles fall toward the ground. The behavior of the fluid depends upon the solids concentration relative to the amount of hot gases (i.e., solids-gas ratio). High concentration density flows are called "pyroclastic flows" and are essentially nonturbulent and confined to valleys. Low concentration density flows are called "pyroclastic surges" which can expand over hill and valley like hurricanes. Temperatures may be as hot as 900 degrees Celsius, or as cold as steam ( see "base surges" in section on Hydroclastic Processes).

Pyroclastic flows and surges are potentially highly destructive owing to their mass, high temperature, high velocity and great mobility. Deadly effects include asphyxiation, burial, incineration and crushing from impacts. Many people and the cities of Pompeii and Herculaneum were destroyed in 79 AD from an erupion of Mount Vesuvius; 29,000 people were destroyed by pyroclastic surges at St. Pierre, Martinique in 1902; >2000 died at Chichónal Volcano in southern Mexico in 1982 from pyroclastic surges. The only effective method of risk mitigation is evacuation prior to such eruptions from areas likely to be affected by pyroclastic density currents.


Lahars are part of the family of debris flows that are fluids composed of mixtures of water and particles of all sizes from clay-size to gigantic boulders. The abundance of solid matter carries the water, unlike watery floods where water carries the fragments. Debris flows have the viscous consistency of wet concrete, and there is a complete transition to watery floods. Lahars are composed of volcanic particles and originate directly or indirectly from volcanic action. Lahars can form by hot pyroclastic surges or flows entering watershed systems or flowing over snow and ice, by eruptions through crater lakes, by heavy rains on loose volcanic debris -- that is, any process by which volcanic particles can become saturated by water and move downslopes. They can move with velocities as low as 1.3 m/s to as great as 40 m/s on steep slopes (1 m/s = 2.55 miles per hour). They are known to have travelled as far as 300 km (1 km = 0.63 miles). Lahars have destroyed many villages and lives living on Indonesian volcanoes because most people live in valleys where lahars flow. The 21,000 lives lost at Armero, Colombia, was from a lahar that formed during the eruption of Nevado del Ruiz in 1985. It was generated by meltwater from the interaction of pyroclastic surges with snow and ice, from a very small eruption. Lahars can transform into regular floods as they become increasingly diluted with water downstream. This phenomenon was first discovered at Mount St. Helens where hot pyroclastic surges transformed to lahars, which further transformed to hyperconcentrated streamflow and then to normal stream-flow turbulence (floods).

Debris-flow Avalanches

The eruption of Mount St. Helens on May 18, 1980 started with a relatively small volcanic earthquake that caused collapse of the north side of the volcano because it was oversteepened and therefore unstable. When the landslide occurred, it decreased the pressure on the pressurized interior of the volcano which expanded explosively to form a lateral blast that devastated the countryside north of the volcano. Most of the debris flow avalanche was diverted down the North Fork Toutle River, but some moved directly northward over a 300 meter ridge and down into the next valley. Since the 1980 Mount St. Helens eruption, dozens of volcanoes that have given rise to avalanches have been discovered. For example, 40 avalanches exceeding 1 Km3 in volume, and 22 with a volume of less than 1 km3, are now known from the Quaternary alone, and 17 historic volcanic avalanches have been identified. The hilly topography north of Mount Shasta in northern California is now known to be the result of a have debris-flow avalanche. Some are known to extend up to 85 km from their sources and to cover tens to more than 1000 km2 in area.

Lava flows

Lava flows rarely threaten human life because lava usually moves slowly -- a few centimeters per hour for silicic flows to several km/hour for basaltic flows. An exceptionally fast flow (extremely rare) at Mt. Nyiragongo, Zaire (30-100 km/hour), overwhelmed about 300 people. Major hazards of lava flows -- burying, crushing, covering, burning everything in their path. Sometimes lava melts ice and snow to cause floods and lahars. Lava flows can dam rivers to form lakes that might overflow and break their dams causing floods. Methods for controlling paths of lava flows: (1) construct barriers and diversion channels, (2) cool advancing front with water, (3) disruption of source or advancing front of lava flow by explosives.

Tephra falls and Ballistic Projectiles formed on Land

Tephra consists of pyroclastic fragments of any size and origin. It is a synonym for "pyroclastic material." Tephra ranges in size from ash (<2 mm) to lapilli (2-64 mm) to blocks and bombs (>64 mm). Densities vary greatly, from that of pumice (<0.5)) to solid pieces of lava with density about 3.0. Blocks from basement material may exceed 3.0. Material may be juvenile (formed of magma involved in the eruption ) or accidental (derived from pre-existing rock).

Tephra fall and ballistic projectiles endanger life and property by (1) the force of impact of falling fragments, but this occurs only close to an eruption, (2) loss of agricultural lands if burial is greater than 10 cm depth, (3) producing suspensions of fine-grained particles in air and water which clogs filters and vents of motors, human lungs, industrial machines, and nuclear power plants, and (4) carrying of noxious gases, acids, salts, and, close to the vent, heat. Burial by tephra can collapse roofs of buildings, break power and communication lines and damage or kill vegetation. Even thin (<2 cm) falls of ash can damage such critical facilities as hospitals, electic-generating plants, pumping stations, storm sewers and surface-drainage systems and sewage treatment plants, and short circuit electric-transmission facilities, telephone lines, radio and television transmitters. When dispersed widely over a drainage basin, tephra can change rainfall/runoff relationships. Low permeability of fine ash deposits leads to increased runoff, accelerated erosion, stream-channel changes and hazardous floods. In contrast, thick, coarse-grained deposits closed to the source can increase infiltration capacity and essentially eliminate surface runoff.

Many of the hazards of tephra falls can be mitigated with proper planning and preparation. This includes clearing tephra from roofs as it accumulates, designing roofs with steep slopes, strengthening roofs and walls, designing filters for machinery, wearing respirators or wet clothes over the mouth and nose because tephra can contain harmful gases adsorbed on the particles as acid aerosols and salt particles.

Volcanic Gas

Magma is molten rock containing dissolved gases that are released to the atmosphere during an eruption and while the magma lies close to the surface from hydrothermal systems. The most abundant volcanic gas is water vapor; other important gases are carbon dioxide, carbon monoxide, sulfur oxides, hydrogen sulfide, chlorine, and fluorine. The gases are transported away from vents as acid aerosols, as compounds adsorbed on tephra and as microscopic salt particles. Sulfur compounds, chlorine and fluorine react with water to form poisonous acids damaging to the eyes, skin and repiratory systems of animals even in very small concentrations. The acids can destroy vegetation, fabrics and metals. Atmospheric veils of dust or acid aerosols caused by large-volume explosive eruptions can effect regional or global climate.

Most volcanic gases are noxious and smell bad, but they can cause mass fatalities. An rare case of mass deaths by volcanic gases in 1986 at Lake Nyos, in Cameroon, West Africa. Tons of carbon dioxide spilled out of Lake Nyos, and flowed silently down a canyon and through 3 village occupied by 1700 people. They and 3000 cattle died instantly from lack of oxygen.

Carbon dioxide emissions are now being monitored at Mammoth Mountain, California.


A tsunami is a long-period sea wave or wave train generated by a sudden displacement of water. Tsunamis travel at very high speeds through deep water as low broad waves and build to great heights as they approach the shallow bottom of shores. Most are caused by fault displacements on the sea floor, but many have been caused by volcanic action. The eruption of Krakatau in 1883 produced tsunamis that killed 36,000 people. The pyroclastic flow generated by this eruption displaced the water that initiated the tsunamis.

Copyright (C) 1997, by Richard V. Fisher. All rights reserved.

What causes a volcano to erupt and how do scientists predict eruptions?

When a part of the earth's upper mantle or lower crust melts, magma forms. A volcano is essentially an opening or a vent through which this magma and the dissolved gases it contains are discharged. Although there are several factors triggering a volcanic eruption, three predominate: the buoyancy of the magma, the pressure from the exsolved gases in the magma and the injection of a new batch of magma into an already filled magma chamber. What follows is a brief description of these processes.

As rock inside the earth melts, its mass remains the same while its volume increases--producing a melt that is less dense than the surrounding rock. This lighter magma then rises toward the surface by virtue of its buoyancy. If the density of the magma between the zone of its generation and the surface is less than that of the surrounding and overlying rocks, the magma reaches the surface and erupts.

Magmas of so-called andesitic and rhyolitic compositions also contain dissolved volatiles such as water, sulfur dioxide and carbon dioxide. Experiments have shown that the amount of a dissolved gas in magma (its solubility) at atmospheric pressure is zero, but rises with increasing pressure.

For example, in an andesitic magma saturated with water and six kilometers below the surface, about 5 percent of its weight is dissolved water. As this magma moves toward the surface, the solubility of the water in the magma decreases, and so the excess water separates from the magma in the form of bubbles. As the magma moves closer to the surface, more and more water exsolves from the magma, thereby increasing the gas/magma ratio in the conduit. When the volume of bubbles reaches about 75 percent, the magma disintegrates to pyroclasts (partially molten and solid fragments) and erupts explosively.

The third process that causes volcanic eruptions is an injection of new magma into a chamber that is already filled with magma of similar or different composition. This injection forces some of the magma in the chamber to move up in the conduit and erupt at the

Although volcanologists are well aware of these three processes, they cannot yet predict a volcanic eruption. But they have made significant advances in forecasting volcanic eruptions. Forecasting involves probable character and time of an eruption in a monitored volcano. The character of an eruption is based on the prehistoric and historic record of the volcano in question and its volcanic products. For example, a violently erupting volcano that has produced ash fall, ash flow and volcanic mudflows (or lahars) is likely to do the same in the future.

Determining the timing of an eruption in a monitored volcano depends on measuring a number of parameters, including, but not limited to, seismic activity at the volcano (especially depth and frequency of volcanic earthquakes), ground deformations (determined using a tiltmeter and/or GPS, and satellite interferometry), and gas emissions (sampling the amount of sulfur dioxide gas emitted by correlation spectrometer, or COSPEC). An excellent example of successful forecasting occurred in 1991. Volcanologists from the U.S. Geological Survey accurately predicted the June 15 eruption of the Pinatubo Volcano in the Philippines, allowing for the timely evacuation of the Clark Air Base and saving thousands of lives.

PDRRMO Office Location

Provincial Sports Complex, Brgy. Bolbok, Batangas City
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