Coastal Hazards in the Philippines

Since the Philippines is made up of thousands of islands, there is a lot of coastline to deal with. Although the wind and waves are the major factors for coastal erosion, human development and coral reef destruction have also played a significant role. Manila, the capital city, is a coastal city of 2 million people with whole communities (as well as major transportation systems-freeways and highways) at risk of falling into the sea. Coastal erosion, flooding, storm surges, monsoons, typhoons, and tsunamis are all coastal hazards faced by this island nation. 

(MGB Logo) 

 The Mining and Geosciences Bureau of the Philippines is responsible for monitoring and reporting on coastal hazards, as well as maintaining coastal hazard maps, establishing danger areas, and determining the causes of erosion events.

In Zambales in 2013, they saw a 80-100 meter section of beach collapse near a resort, decreasing the coastline by about 10 meters in that area. They originally thought it might have been due to a sinkhole, but instead determined it was due to a combination of coastal erosion and an underground river. A danger area was established until they could determine if future instability could cause another collapse.

When looking at the Coastal Hazards Maps available through MGB, much of the data is incomplete. So I'm not sure how useful these maps are. Also the priority seems to be on flooding direction and flooding hazards, rather than erosion issues. Considering the severity of flooding that happens annually near coastal and lakeside areas, it is not surprising that flooding has been the major funding priority.

References: http://www.mgb.gov.ph/, http://www.philstar.com/nation/2013/07/02/960479/mgb-coastal-erosion-caused-zambales-beach-collapse, http://newsinfo.inquirer.net/434379/beach-erosion-in-zambales-caused-by-underground-river-geologists-say, http://www.gmanetwork.com/news/story/314186/news/regions/portion-of-zambales-beach-collapses, http://gdis.denr.gov.ph/mgbpublic/#identify, https://ideas.repec.org/p/eep/pbrief/pb2009082.html

Monsoons - A complex hazard for the Philippines

Monsoons, part of the rainy season cycle in the Philippines, are both a norm and a hazard. Compounded by typhoon activity, which will be explored later, monsoon rains can lead to flooding and landslides.
Monsoons are a natural part of the weather cycle in the Philippines, that have to do with the effect of difference in temperature between the ocean and land on the sea breezes. NOAA monitors global monsoon activity in their Climate Prediction Center. This information on ocean temperatures is available online for anyone to access.

 (Table from NOAA)
In the Philippines, there are the summer monsoons (June-November), the "rainy" season, that move westerly and bring heavy drenching rainfall, and there are winter monsoons (December-May) that move easterly, and can bring dry conditions (and sometimes drought). The Philippines has between 70% and 85% humidity, year-round, and there is also rainfall year-round.

(Graphic from Panahon TV and PEGASA)
Monsoon seasons are unpredictable, they can start early or start late, bring too little rain or bring too much. This can create significant problems for growing food and tending livestock, as well as for dealing with the secondary consequences of flooding, mudslides, landslides, and sinkholes.

 (Photo from Photos of the Week, Sf.Co.Ua, August 2012)
PAGASA (Philippine Atmospheric, Geophysical and Astronomical Services Administration) is the weather monitoring agency in the Philippines, they issue weather warnings about rain, typhoons, and flooding. They are responsible for forecasting for aviation and marine hazards that could impact transportation and shipping, and they also issue impact assessments for agriculture. They have a rainfall and thunderstorm warning system, on a spectrum of advisory-alert-emergency for rainfall, and information-watch-advisory for thunderstorms, the outreach methods besides their website also include social media and SMS messages to affected areas. There is also a PAGASA app for android phones.

 (Photo from Photos of the Week, Sf.Co.Ua, August 2012)

References: http://www.cpc.ncep.noaa.gov/products/Global_Monsoons/Global-Monsoon.shtml, http://www.wrh.noaa.gov/twc/monsoon/monsoon_whatis.pdf, http://www.pagasa.dost.gov.ph/, http://www.pagasa.dost.gov.ph/index.php/climate-of-the-philippines, http://www.pagasa.dost.gov.ph/index.php/agriculture/impact-assessment-for-agriculture, http://www.pagasa.dost.gov.ph/index.php/20-weather/29-rainfall-warnings, http://photo.sf.co.ua/id22

Mass Wasting-Landslides & Mudslides in the Philippines

Unfortunately the islands of the Philippines are highly susceptible to mass wasting. Not only is there a significant amount of coastline, but most of the islands are mountainous, and the upland areas and areas near volcanoes are particular vulnerable. Increasing the risk are earthquakes, high rainfall, typhoon and monsoon activity, and volcanoes. Increasing the hazard is the development of upland areas, homes on slopes, homes made of flimsy building material, and lack of reinforcement and drainage infrastructure.

(Photo from PHIVOLCS)

PHIVOLCS is particularly concerned with earthquake-induced landslides, and therefore they have a hazard map outlining the various levels of hazards. They have hazard maps available by region as well, that are more detailed.

It is not surprising that they have focused specifically on this landslide hazard because of the deadly 2006 Southern Leyte mudslide that claimed the lives of over 1,100 people. This landslide was the result of a period of heavy rainfall followed by a very small M 2.6 earthquake, burying an entire village including an elementary school that was in session at the time, killing all but one child and one adult at the school, as well as a thousand others in the village of Saint Bernard. Possible contributing factors were logging and mining activity in the area. A previous landslide in 2003 claimed the lives of 200 people in this same area. Although some residents were aware of the danger in 2006 and had evacuated, some returned too soon, encouraged by the rainfall subsiding, and were caught in the mudslide.

(Photo from Robert Peterson, US Navy)

September and October are considered high risk months for landslides because of late season typhoons. Just one of many landslides in 2013, the photo below illustrates the slope conditions, soil texture, and building materials that resulted in the death of at least 10 people in Barangay Cawag.

(Photo from Philippine Star Global)

As far as methods to reduce landslide hazards, very few are evident from my research. The main strategies seem to be community engagement through education and memorial events, and decentralization (or rather the strengthening of the responsibilities of individual provinces to address their hazards within their own jurisdictions). Also, just simple things, like improving communication throughout the country can help with disaster management and issuing warnings for vulnerable areas, and reliable communication systems are not currently widely available throughout all the Philippine islands.

References: http://www.navy.mil, http://www.phivolcs.dost.gov.ph/index.php?option=com_content&view=article&id=82&Itemid=500025,
http://www.philstar.com/headlines/2013/09/24/1237497/landslides-floods-kill-22-zambales, https://www.scribd.com/document/70631853/Strengthening-Disaster-Risk-Reduction-in-the-Philippines-Strategic-National-Action-Plan-2009-2019

Volcanism of the Philippines

The Philippines is a very volcanic island nation. There are between 23-53 active volcanoes at any time, another 30 potentially active volcanoes, and hundreds of inactive ones, and those are just the ones above sea-level. The eruptions of the volcanoes of the Philippines have been some of the most deadly and costly, having a great number of volcanic eruptions causing tsunamis and lahars. There are two major North-South volcanic arcs, one in Luzon, and one in Mindanao. At the moment, the six most active volcanoes in the Philippines are: Taal, Mayon, Bulusan, Hibok-Hibok, Pinatubo and Kanlaon.

 (map from PHIVOLCS)

PHIVOLCS (The Philippine Institute of Volcanology and Seismology) has been praised with being responsible for saving the most lives from volcano-related disasters in the Philippines. Before the 1951 eruption at Hibok-Hibok, which killed 3,000 people, there was no government agency in charge of dealing with volcanoes.

(photo from Hibok-hibokrocks.blogspot)
Today PHIVOLCS have a great site that has lists of active, potentially active, and inactive volcanoes. They include a series of definitions of volcano related phenomena (both direct and indirect), such as lahars, pyroclastic blasts, and tsunami-generation. They have several volcano monitoring stations (see my post on September 9, 2016, with a map of where these are). They monitor volcanoes through four main strategies: a seismic network, a ground deformation network, hot-spring temperature and flow-rate measurements, and visual observation.
PHIVOLCS uses a 0-5 Volcano alert system, where O means no alert/or quiet, and 5 means hazardous eruption in progress. They issue warnings for no fly zones in ares with high ash, as volcanic ash can damage airplane engines. They issue evacuation warnings and establish safety perimeters (from 4-9 kilometers depending on alert level between 1-4), they also issue warnings for ash fall in residential and farming areas. They are responsible for issuing warnings for riverside communities that could be affected by ash contamination in the water downstream of volcanoes, especially following periods of heavy rainfall.

(photo from Newhall, USGS)
The most recent eruption was on September 16, a 4-minute long phreatic (steam-blast) eruption at the Bulusan Volcano on the southeastern part of the island of Luzon (250 km from Manila). Bulusan regularly erupts these steam-blasts, which eject steam and ash into the air. Although some of the blasts are of short duration, the ash can be carried by the wind to nearby towns and water sources. Bulusan is a strato-volcano so people in the area take precautions because an eruption of Mount Bulusan could be highly explosive. Bulusan Volcano Natural Park surrounds the volcano, but there are evacuation procedures for nearby farms and PHIVOLCS establishes and adjusts the threat level as they evaluate the volcano. The alert level for Bulusan is currently 1, which means there is a low level of volcanic unrest. There is currently a four-kilometer Permanent Danger Zone around the volcano, and the area directly over the volcano is considered a no-fly zone during periods of any visible activity.

References: http://volcano.si.edu/reports_weekly.cfm#vn_273010, http://www.phivolcs.dost.gov.ph/index.php?option=com_content&view=article&id=50&Itemid=86, https://www.volcanodiscovery.com/philippines.html, http://hibok-hibokrocks.blogspot.com/2011/12/time-magazine-article-december-1951-mt.html, http://geographic.org/photos/volcanoes/volcano_photos_314.html

Seismicity Map of the Philippines

This is a follow-up from my post on Friday, to include this awesome map and some recent data.

This map of the distribution of active faults and trenches in the Philippines clearly shows the convergence zones off both the East and West coasts of the country, crossing onto land only on the island of Mindoro. There is a collision zone mostly near the western waters of Panay, but also crossing over the southwest tip of the island. There is also a transform boundary to the northeast of Pulong Polillo in the Philippine Sea. As you can see from the map there are a multitude of faults ranging through most of the islands, the notable exception is Palawan in the West.
From the good folks at PHIVOLCS:

Recent activity from IRIS: Since September 1st of this year, there have been 9 significant earthquakes in the southern region of Mindanao, ranging from M4.6 to M5.9. The most recent was at 16:29 UTC, on September 10, 2016, a M5.3.

References: http://www.phivolcs.dost.gov.ph/, http://ds.iris.edu/seismon/eventlist/index.phtml?region=Polynesia

Earthquake Mitigation Strategies in the Philippines

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) is the Philippine equivalent of the USGS, and has established some innovative earthquake risk reduction projects in the Philippines.

In collaboration with Japan, PHIVOLCS has conducted structural integrity studies of concrete hollow block houses, one of the main building types of residential dwellings in the Philippines. They have developed a self-check for earthquake safety entitled "How Safe is Your House" that addresses vulnerability of houses based multiple factors, that allows people to evaluate the potential integrity of their own home.

One of their culturally-inspired projects was Handa...Awit...Lindol! (Ready...Sing...Earthquake!), a collection of (Karaoke-style) songs for preparedness for earthquakes and natural hazards. Since singing is a national pastime, this creative University of the Philippines Diliman funded project incorporates hazard education and music. Check out the "Pacific Ring of Fire" song, the "Intensity" song that describes the differences between the magnitudes of earthquakes, or the rock/rap style "Don't Panic" song that tells you what to have in your emergency kit! (https://soundcloud.com/up-diliman-ovcrd/sets/handa-awit-lindol)

PHIVOLCS also offers a series of hazard maps, for faults and trenches, earthquakes, earthquake-induced landslides, liquefaction susceptibility, tsunami, and volcanoes.

According to PHIVOLCS:

"The Philippines has a total of 65 seismic stations, 29 of which are manned, 30 are unmanned, and 6 volcano stations. The central operating station is located at PHIVOLCS Main Office, Diliman, Quezon City. All information is received at the Data Receiving Center (DRC), which is operated 24/7 by the Seismological Observation and Prediction Division (SOEPD)." (PHIVOLCS)

 

(Map from PHIVOLCS.dost.gov. ph)

The Philippines coordinates with the Global Seismographic Network, and they have shared data from their Davao station since 1994. The broadband connection from the station operated by PHIVOLCS, updates the data to the global network about every 10 minutes.

References: http://www.phivolcs.dost.gov.ph/images/CHB_Test_Briefing_3_0001.mp4, http://www.phivolcs.dost.gov.ph/images/Flyer-How-Safe-Is-Your-House.pdf, https://soundcloud.com/up-diliman-ovcrd/sets/handa-awit-lindol, http://www.phivolcs.dost.gov.ph/index.php?option=com_content&view=article&id=44&Itemid=300083, http://earthquake.usgs.gov/monitoring/gsn/, http://earthquake.usgs.gov/monitoring/operations/station.php?network=IU&station=DAV,

The Philippines

The Philippines is a Southeast Asian island nation located at 13 00 N, 122 00 E. The Philippine North-South archipelago includes over 7100 islands. The lowest elevation is at sea-level, while the highest elevation is Mount Apo at 2,954 meters. The country is divided into three main regions, the northern Luzon, the central Visayas, and the southern Mindanao. The northern island of Luzon, houses the capital city, Manila.
(Map and flag from CIA.gov)

To say the Philippines is located in an active tectonic region is putting it mildly. You can see on the USGS map below the Philippine Sea Plate borders the island nation to the East, subducting under the Sunda Plate, while the Eurasian Plate is subducting under the west coast of Luzon.
"The 1,200-km-long Philippine fault zone (PFZ) is a major tectonic feature that transects the whole Philippine archipelago from northwestern Luzon to southeastern Mindanao. This arc-parallel, left-lateral strike slip fault is divided into several segments and has been the source of large-magnitude earthquakes in recent years." (The Philippine Institute of Volcanology and Seismology)
Earthquakes and volcanoes are a part of life in the Philippines, as well as tsunamis, typhoons, flooding and landslides.

(Map from USGS)
References: http://www.gov.ph/, https://www.cia.gov/library/publications/the-world-factbook/geos/rp.html, http://pubs.usgs.gov/of/2010/1083/m/, http://www.phivolcs.dost.gov.ph/