FACT CHECK: Wind speed not sole factor in determining degree of storm damage

Claim: Super Typhoon Rolly, which hit the Philippines in 2020, affected fewer people than Severe Tropical Storm Kristine despite having a lower wind speed.

Rating: MISSING CONTEXT

Why we fact-checked this: The Facebook post bearing the claim was posted by a page with 596,000 followers on November 4. As of writing, it has 31,000 reactions, 4,600 comments, and 22,000 shares.

The post showed a graphic comparing death tolls due to Super Typhoon Yolanda, Super Typhoon Rolly, and Severe Tropical Storm Kristine under the administrations of former president Benigno Aquino III, Duterte, and President Ferdinand Marcos Jr., respectively.

The graphic also included the highest wind speeds recorded for each tropical cyclone. The comparison implied that the death toll due to Kristine was higher even though its maximum wind speed was lower compared to Rolly, and that this could be attributed to the government’s response. The post’s caption implied that of the three presidents, Duterte’s leadership had been the most effective: “If a leader knows what he’s doing, calamity damage will not be as intense.”

The post was uploaded a few days after the Marcos administration was criticized for “clueless” disaster management during Kristine’s onslaught last month.

The bottom line: While it is true that the death toll from Kristine was higher compared to Rolly — at least 116 died due to Kristine compared to 25 due to Rolly — wind speed is not the sole factor in determining the degree of impact of a tropical cyclone.

Philippine Atmospheric, Geophysical, and Astronomical Services Administration (Pagasa) senior weather specialist Robb Gile told Rappler in an email that three key factors affect the degree of potential impacts of any weather hazard:

The magnitude, duration, and extent of the hazard
The exposed elements to the hazard/s (e.g. people, structures, lifelines)
The vulnerability of the exposed elements (e.g. how the exposed element behaves under increasing magnitude, duration, and extent of the hazard)

“In the case of STY Rolly in 2020, although it was considered one of the strongest tropical cyclones to make landfall in the Philippines, much of the severe weather hazards (heavy rains, severe winds, storm surge) were only observed in Bicol Region and portions of CALABARZON (mainly Quezon) since Rolly rapidly weakened during its passage. On the other hand, the severe weather hazards related to STS Kristine, despite being weaker at the time of passage than Rolly, affected a much wider area (e.g., Metro Manila, CALABARZON, Bicol Region),” Gile said.

Gile also noted that Kristine’s heavy rainfall in Bicol Region and CALABARZON was “considerably higher than those observed during STY Rolly especially when compared against rainfall return periods and monthly normal in the affected areas.”

The differences in the extent of damage can also be observed during 2020’s Typhoon Ulysses and 2021’s Typhoon Odette. While both tropical cyclones had lower wind speeds compared to Rolly, the two cyclones caused more damage as Ulysses mainly impacted the densely crowded Metro Manila and adjacent provinces while Odette made multiple landfalls.

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Criticism of government response: Like the Marcos administration, Duterte also came under fire for his government’s response to Rolly, with the hashtag #NasaanAngPangulo trending on social media platforms at the time. The former president also drew similar criticism during the onslaught of Ulysses and Odette.

The misleading post was uploaded amid the growing political rift between the Marcoses and the Dutertes. [READ: (ANALYSIS) The political divorce rocking the Philippines]

Rappler has previously debunked similar false claims on natural disasters:

– Kyle Marcelino/Rappler.com

Kyle Marcelino is a Rappler fact check contributor. This fact check was reviewed by a member of Rappler’s research team and a senior editor. Learn more about Rappler’s fact-checking mentorship program here.

Keep us aware of suspicious Facebook pages, groups, accounts, websites, articles, or photos in your network by contacting us at factcheck@rappler.com. Let us battle disinformation one Fact Check at a time.

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