Lahars—Mount Pinatubo’s Aftermath

BY AWAKE! CORRESPONDENT IN THE PHILIPPINES

HOUSES inundated. Businesses ruined. Vehicles swept away. Buildings covered. Thousands of people forced to flee. Others trapped, not able to flee. What caused this? Earthquake? Avalanche? No. This is the continuing scenario created by lahars (läʹhärs). What are they? Lahars are flows composed of water and volcanic sediment, including loose ash, pumice, and debris from present as well as former eruptions.

Chances are that a decade ago you had never even heard of the Philippines’ Mount Pinatubo. But after a massive eruption on June 15, 1991, “Pinatubo” became a household word in many parts of the world. After sleeping for almost 500 years, Mount Pinatubo disgorged its volcanic contents in one of the most gigantic mushroom clouds of this century. Ash, sand, and rocks spewed forth from the volcano and rained down on the land in amounts that humans have rarely seen.a

The volcano ejected a huge volume of material more than 12 miles [20 km] into earth’s atmosphere. Although some of this came back down to the earth, large amounts of dust remained in the sky—and not just dust but great quantities of sulfur dioxide, some 20 million tons of it!

You likely recall some of the global effects: outstandingly beautiful sunsets for a period of time; unusually bright total eclipse of the sun in Mexico and nearby areas in 1991; altered weather patterns, including a cooling effect on parts of the Northern Hemisphere; and increased destruction of earth’s ozone layer. Or you may have heard of the increased hunger and disease that affected people who were displaced by the eruption.

The Long-Lasting Aftermath

One of the most serious aftermaths of Pinatubo’s eruption, and perhaps one that has escaped notice in much of the world, is the phenomenon known as lahar. As mentioned in the opening paragraph of this article, lahars have resulted in untold suffering for tens of thousands of people. Because of the lahars, the consequences of Mount Pinatubo’s eruption are not all past. They are being felt right up to the present. You may not have been affected personally, but in the vicinity of Mount Pinatubo, businesses, jobs, homes, lives, and even whole towns continue to be wiped out. The culprits are Pinatubo’s lahars.

Although many act like muddy rivers with unusual amounts of sediment, when the lahar contains over 60 percent sediment, it begins to take on the nature of flowing concrete. This can be extremely devastating. A Technical Primer on Pinatubo Lahars states: “These slurries are so dense (more than twice the density of water) that large boulders, rock-filled gabions, vehicles, concrete buildings, and even bridges are lifted and floated away.”

How do lahars get started? You will recall that Mount Pinatubo ejected vast amounts of material when erupting. Some of it went up into the atmosphere, but much remained on the mountain and nearby vicinity as pyroclastic (formed by volcanic action) flow deposits. How much? According to a Philippine Institute of Volcanology and Seismology report, 235 billion cubic feet [6.65 billion cu m]. U.S. volcanologist C. G. Newhall says enough debris came out to “pave a four-lane freeway back and forth across the US at least 10 times.” Of this, 122 billion cubic feet [3.45 billion cu m] was in erodible form—just waiting for rains to come and wash it down to lower elevations, creating lahars. In the Philippines, tropical storms and typhoons can mean extra trouble. Large amounts of rain can fall in a short period of time, resulting in massive lahars.

This is exactly what has been happening for several years. Again and again, storms have soaked volcanic debris with water, mobilizing it. Lahars have turned rich farmland into wasteland and towns into rooftops sticking above the ground. In some cases, this has happened overnight. Thousands of homes have been destroyed, and people have been uprooted from their birthplace, forced to start a new life in another area. Up to the beginning of 1995, lahars had moved 63 percent of the pyroclastic material into the lowlands, but that still left 37 percent on the mountain, just waiting to create future havoc. And much of the 63 percent that has already come down remains a threat. Water from heavy rains carves out channels in material previously deposited upstream. This then causes the lahar to move again, endangering lives and property further downstream. In July 1995 the Manila Bulletin reported: “Ninety-one barangays (villages) . . . have been erased from the map of Central Luzon, buried under tons of volcanic debris.”

Disaster Again

On Saturday evening, September 30, 1995, severe tropical storm Mameng (internationally known as Sybil) affected Luzon. Large amounts of rain fell in the area of Mount Pinatubo. This spelled disaster. Lahars were on the move again. Anything in their path was engulfed. In one area a control dike gave way, exposing previously undisturbed areas to lahars as deep as 20 feet [6 m]. Homes of less than two stories were completely inundated. People scrambled to rooftops to save their lives. Where the lahar was particularly thick, it carried boulders, vehicles, and even homes with it.

Flooding is another effect of the lahars, since they change the course of rivers and water drainage. Thousands of homes were covered by water, including many owned by families of Jehovah’s Witnesses, as well as a number of Kingdom Halls.

Others had even more unfortunate experiences. A person will sink in a moving lahar or in the mud recently deposited by one, making it very difficult to escape. Only after a number of hours or days will the material be hard enough to walk on. How did people escape? Some stayed on rooftops or in trees above the lahar until walking was possible. Others hung on to or walked on telephone cables, since the lahar had reached that height. Some crawled on the semihardened mud left by the lahar. A number did not make it. The government sent helicopters to the harder-hit areas, plucking people from rooftops.—See the accompanying article “We Were Rescued From a Lahar!” for further details.

Love Moves Others to Help

Jehovah’s Witnesses were happy to learn that although many homes and some Kingdom Halls were lost or badly damaged, none of their Christian brothers and sisters lost their lives. Obviously, though, the need was great among those hit by lahars or flooding. Some Witnesses escaped with only the clothes they were wearing, which were soaked with lahar mud. How did fellow Christians respond to the need?

Congregation elders from the immediate area made efforts to determine if their Christian brothers were safe or needed help to evacuate. This was done with great difficulty, since lahar deposits were still soft in many areas. Guillermo Tungol, an elder in the Bacolor Congregation, said: “We went to help. We walked on the telephone cables to get to the brothers.” Wilson Uy, a full-time minister in the same congregation, added: “We were almost unable to get there because we had to go through chest-deep water that was quite fast-moving.” But, with care, they made it and were able to determine the condition of congregation members and assist where possible.

By Monday morning, October 2, the Watch Tower Society’s branch office was well aware of the need. Would the 345 volunteer workers at the branch be able to help? Yes! The response was immediate. By ten o’clock in the morning, just these workers alone contributed close to one ton of clothing for their suffering Christian brothers. This was dispatched along with some food and funds by means of a truck that delivered the items the same day.

Within days, congregations in the Metro-Manila area were made aware of the need. More than five tons of additional clothing was soon sent, along with other needed supplies. One Witness from Japan was visiting the Philippines at the time of the disaster. She had just come from Hong Kong, where she had purchased a number of clothing items for herself. When she found out about the plight of her fellow Christians near Mount Pinatubo, she gave them all the clothes she had bought and returned to Japan without them. How refreshing to see true Christians showing love to those in need—not just by wishing them well but by ‘giving them the necessities for their body.’—James 2:16.

Commendable, too, is the fact that Jehovah’s Witnesses did not allow such occurrences to dampen their zeal for spiritual things. Christian meetings continued—in one case even where the water was ankle-deep in the Kingdom Hall itself. Realizing the importance of getting the Bible’s message to others, these Christians continued preaching from house to house. Some had to wade through water to get to the area where they were to witness—where it was not quite as flooded. They carried clothes with them and changed at a drier location. So even though these Christians were suffering themselves, they did not let this stop them from showing concern for others.

Yes, Pinatubo’s aftermath is more than what many realized it would be. It is a story that will go on for some years yet. Efforts have been made to control the lahars, but sometimes that is beyond man’s ability. How pleasing it is to see that when such situations arise, true Christians use them as an opportunity to demonstrate their love for God and neighbor!

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How Mount Pinatubo Affected the World

ONCE a volcanic eruption of the scale of Mount Pinatubo’s tapers off or quits, that is the end of it. Right? Not at all! Note some of the lingering global effects.

◼ You may have observed outstandingly beautiful sunsets for a period of time after the eruption.

◼ Scientists in Mexico were surprised at the unusually bright total eclipse of the sun on July 11, 1991. The reason? The eruption of Mount Pinatubo. Its dust particles scattered the corona light more than normal.

◼ Weather was also affected. About three months after the eruption, it was reported that Tokyo, Japan, was receiving about 10 percent less direct sunlight than usual. Volcanic ash blocked out a portion of sunlight. Science News indicated a drop of about 2 degrees Fahrenheit [1 degree C.] in average temperature in parts of the Northern Hemisphere.

◼ Another effect was the increased destruction of earth’s ozone layer. Sulfuric acid that was in the atmosphere as a result of the eruption combined with man-made chlorines, resulting in a decline of ozone. The ozone layer normally provides an atmospheric shield that helps protect people from developing cancer. Soon after the eruption, ozone levels in Antarctica dropped to near zero; at the equator, levels dropped by 20 percent.

◼ Hunger and disease were further negative effects. People displaced by the volcano were forced to live temporarily in evacuation centers, where sickness spread rapidly. Particularly hard hit were the Aeta, a tribal people forced from their land by the eruption and thrown into an environment they were not accustomed to.

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Evacuees from flooded or lahar-stricken areas

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House carried by a lahar

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Two-story buildings covered up to roof level

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Much beautiful farmland turned into wasteland because of lahars

[Pictures on page 19]

Top: Bank building at Bacolor, Pampanga, half covered by a lahar, March 1995

Bottom: Same bank fully covered by a later lahar, September 1995