Column: Monthly Disaster Review and Outlook: Volume 85, September 2023 – World

General review of September 2023

In September 2023, a total of 111 disasters were reported. This is 42.49% less than the number of disasters reported in September last year. ASEAN member states affected in September 2023 are Cambodia, Indonesia, Myanmar, Philippines, Thailand and Vietnam. Most of the disasters (54.95%) occurred in Indonesia and accounted for 43.6% of the victims (about 670K persons), the highest number of victims during this reporting period. The share of disaster affected population for other ASEAN member countries is as follows: (1) Indonesia – 43.62%, (2) Philippines – 28.07%, (3) Thailand – 14.16%, (4) Cambodia – 13.13%, (5) Vietnam – 0.42%, (6) Myanmar – 0.39%, and (7) Malaysia – 0.21%. In September 2023, the region affected 223 people per 100,000 people* and displaced 5 people per 100,000 people, which was significantly lower compared to the previous month (36% and 58%, respectively).

Of the total disasters recorded in September 2023, 48.65% of floods occurred in the Northern Hemisphere, and the five-year average (2018–2022) was the highest recorded disaster in September and September of the previous year. ) however, due to the effects of El Niño, drought was the second most reported disaster (29.73%), especially in September 2023 in southern regions of the equator (Indonesia) where 33 times more droughts were reported (33). 15.5 times the five-year (2018-2022) average for drought in September (2) compared to the drought recorded in September of the previous year (1). Compared to historical data (average for September 2018-2022), reported disasters in the region in September 2023 represent 1.5 times more reported disasters, 2.7 times fewer victims, 4.2 times fewer people displaced internally, 1.6 times fewer houses partially damaged, 13.4 times fewer lives lost, and 281 Fewer people suffer from injuries.

Geophysical status for September 2023

Geophysically, 22 significant earthquakes (magnitude ≥ 5.0) were reported by Batan Meteorology, Climatology Don Geophysica (BMKG) and Philippine Institute for Volcanology and Seismology (PHIVOLCS) during September 2023, Indonesia.

Mounts Ibu (alert level II), Semeru (alert level III), Dukono (alert level II), Ili Levodolok (alert level II) and Mayon (alert level 3), Tal (alert level 1), and Kanlan (alert level) in Indonesia. Level 1) is said to be tectonically active (volcano erupting or releasing gas or generating seismic activity) throughout the month of September 2023 in the Philippines.

As of October 1, PHIVOLCS maintained Mayon Volcano at Alert Level 3 (increased trend toward catastrophic eruption). According to PHIVOLCS, volcanic earthquakes, rockfall events, and pyroclastic density current events still occur within a 4-km radius of the crater. Volcanic sulfur dioxide (SO2) emissions averaged 1392 tons/day in September 2023. And a fatal eruption is still possible within weeks. A total of 9,876 families or 38,396 individuals have been affected, according to a report by the NDRRMC on October 11. Out of which, 52 families (195 people) were displaced within 1 evacuation centre. NDRRMC along with other related-agencies/stakeholders has provided assistance worth 7.9M USD to the victims.

* Calculated based on 2023 population data from worldometers.com

Analysis

According to the ASEAN Special Meteorological Center (ASMC), southwest monsoon conditions persisted over the region in September 2023. ASMC noted that prevailing low-level winds were mainly south-southeasterly of the equator. Drier conditions prevailed in many parts of the South Asian region in the south-west or westerly areas north of the equator. Isolated rain was reported in parts of North Sumatra, Malaysia and North East Kalimantan. In the northern ASEAN region, the weather was generally wet as the traditional wet season prevailed. The average daily rainfall and average wind over the region in September 2023 are illustrated in Figure 1. Moderate to heavy rain concentration in the northern and northeastern parts of Thailand and the northern, northwestern and central provinces of Cambodia, especially in low-lying areas. and near river systems, may have contributed to the flooding events that affected 69,000 households in these areas.

Seasonal Outlook

According to the ASEAN Special Meteorological Center (ASMC), the southwest monsoon conditions that prevailed in September 2023 are expected to continue in October. During this period, the prevailing winds in the ASEAN region are expected to blow mostly from the southeast or southwest. Rainy weather is likely to prevail over the northern ASEAN region while dry conditions are expected in the southern part of the region.
By the end of October 2023, weak or variable winds are likely to occur as the inter-monsoon begins. Meanwhile, more rain activity can be expected over most of the equatorial regions.

For the next 3 months, (October-November-December 2023), most of the South ASEAN region is forecast to have a high chance of below normal rainfall, which includes the Philippines. Meanwhile, mainland parts of Southeast Asia are also likely to receive above normal rainfall during this period. El Niño conditions are expected to strengthen in the next few months and last till at least early 2024, while a positive Indian Ocean Dipole (IOD) is present and likely to persist during October-November. El Niño and positive IODs may bring drier conditions to much of the region. Above-normal temperatures are forecast for most of ASEAN during October-November-December 2023.