Tsunami Philippines

Tsunami in the Philippines are extremely rare. 

The last measurable tsunami in the Pilippines affected the northern and the eastern seaboards on March 11, 2011. In that event, tsunami waves of around half a meter, resulting from a relatively shallow and very large 8.9 magnitude earthquake off the coast off Miyagi prefecture, Honshu, Japan, arrived in the early evening and caused a little or no damage, and no loss of life.

Prior to March 2011, the last recorded tsunami in the Philippines, that actually caused loss of life, occurred in the Verde Island Passage (between Batangas & Mindoro Island, affecting Puerto Galera) in the early morning of November 15, 1994, originating from a 7.1 magnitude (Richter) earthquake, 11KM West of the Baco Islands, according to the Philippine Institute of Volcanology and Seismology. The tsunami waves, resulting from the 7.1 magnitude earthquake, were measured at 6 meters in many areas when they reached land, but up to 8.5 meters in a few locations (primarily the Baco Islands) where the bathymetry was favorable; the tsunami waves reached up to 250 meters inland in areas that faced the earthquake epicenter. The death toll was 41 people. 

References: http://www.pgyc.org/tsunami-earthquake.php

1976 Moro Gulf earthquake

The 1976 Moro Gulf earthquake and tsunami took place on August 16, 1976, at 16:11 UTC (on August 17, 1976), near the islands of Mindanao and Sulu, in the Philippines. Its magnitude was calculated as being as high as 8.0 on the moment magnitude scale. The epicenter was in the Celebes Sea between the islands of Mindanao and Borneo. The Pacific Tsunami Warning Center's preliminary magnitude was given as 8.0 on the Richter scale and as 7.9 by other sources. There were many aftershocks following the main earthquake. A major aftershock on August 17 (local date) had a magnitude of 6.8. It was followed by at least fifteen smaller aftershocks.

 

Tsunami damage at Lebak, Mindanao 

Effects:
The initial earthquake was widespread and was felt as far as the central Philippine islands of the Visayas. A massive tsunami devastated 700 kilometers of coastline bordering the Moro Gulf in the North Celebes Sea, resulting in destruction and death in the coastal communities of the Sulu Archipelago and southern Mindanao, including Zamboanga City and Pagadian City. At least 5000 people died during the earthquake and tsunami, with thousands more remaining missing.[4] Some reports say that as many as 8,000 people lost their lives in total, with ninety percent of all deaths the result of the following tsunami.

Initially over 8,000 people were officially counted as killed or missing, 10,000 injured, and 90,000 homeless, making the 1976 Moro Earthquake and Tsunami one of the most devastating disasters in the history of the Philippine Islands. After the initial earthquake the people were unaware of the need to move to higher ground; when the tsunami hit it sucked most of the victims out to sea. Based on the investigation on the affected region it was confirmed that the waves reached up to 4 to 5 metres (13 to 16 ft) when they hit the areas. There were reports of weak tsunami activity as far as Japan, as well as Indonesian Hydrographic Office reports of unusual wave activity affecting the islands of Sulawesi (Celebes Island) and Borneo.

In Zamboanga City, 14 buildings were partially damaged. Zamboanga City was spared from serious damage of the tsunami triggered by this earthquake because the Basilan Island and the Santa Cruz Islands served as a buffer and deflected waves.

Warnings:
The Pacific Tsunami Warning Center (PTWC) in Honolulu issued a Tsunami Watch for the Pacific and queried tide gauge stations in Okinawa, Yap and Malakal. Based on negative reports from these stations, the watch was cancelled. Unfortunately, minutes after the earthquake, a large local tsunami struck the region. There was no time to issue a local warning.

Aid response:
The Philippine Government sent out aid and support as soon as news reached Manila. Later a team of US and Filipino geologists and officials surveyed the disaster zone with the help of the Philippine Air Force. The objective of the survey was to obtain measurements of the tsunami wave heights, extent of inundation and gather additional information on the earthquake and the tsunami and its effects in the region.

Aftermath:
The earthquake occurred at night, when offices and schools in Cotabato, Zamboanga and other cities were unoccupied, therefore the loss of life was greatly reduced. Pagadian, on the other hand, was the only city hardest hit by the tsunami that followed. Although the earthquake had a large magnitude, surprisingly, it produced little ground deformation on land areas. However, there was extensive earthquake damage to buildings, bridges and roads in Mindanao and particularly in the city of Cotabato.

Reference: http://www.ringsurf.com/online/2412-tsunamis_through_history.html

         

The most known volcanoes in the Philippines are Mount Pinatubo, Mount Mayon and the Taal volcano. They are all located on the Northern island Luzon. Mount Mayon is a splendid example of a strato volcano. Mount Mayon rises up 2462 meters above sea level.

          Mayon Volcano is an active volcano in the province of Albay, on the island of Luzon in the Philippines. Renowned as the "perfect cone" because of its almost symmetric conical shape, the mountain was declared a national park and a protected landscape on July 20, 1938, the first in the country. It was reclassified a Natural Park and renamed Mayon Volcano Natural Park in the year 2000. Local folklore refers to the volcano being named after the legendary heroine Daragang Magayon.

Mayon is a classic stratovolcano(composite) type of volcano capped by a small central summit crater. The cone is considered the world's most perfectly formed volcano for its symmetry,[6] which was formed through layers of pyroclastic and lava flows from past eruptions and erosion. The upper slopes of the basaltic-andesitic volcano are steep averaging 35–40 degrees. Like other volcanoes located around the Pacific Ocean, Mayon is part of the Pacific Ring of Fire. It is located on the eastern side of Luzon, near the Philippine Trench which is the convergent boundary where the Philippine Sea Plate is driven under the Philippine Mobile Belt. When a continental plate or belt of continental fragments meets an oceanic plate, the lighter continental material overrides the oceanic plate, forcing it down into the Earth's mantle. Magma may be forced through weaknesses in the continental crust caused by the collision of the tectonic plates. One such exit point is Mayon.

Recorded eruptions:

*1814 eruption: 

*1881–1882 eruption: 

*1897 eruption: 

*1984 and 1993 eruptions: 

*2009–2010 eruption: 

*2013 phreatic eruption:

*2014 renewed activity: On 12 August 2014 a new 30m-50m high lava dome appeared in the summit crater. This event was preceded by inflations of the volcano (measured by precise leveling, tilt data, and GPS), and increases in sulphur dioxide gas emissions.

On 14 September 2014, rockfall events at the southeastern rim of the crater and heightened seismic activity caused PHIVOLCS to increase the alert level for Mayon from 2 to 3, which indicates relatively high unrest and that magma is at the crater and that hazardous eruption is possible within weeks.[60] The rock falls, and visible incandescence of the crater from molten lava and hot volcanic gas indicated a possible incipient breaching of the growing summit lava dome.

On 15 September 2014, NASA's Moderate-Resolution Imaging Spectroradiometer (MODIS) detected thermal anomalies near Mayon's summit, consistent with magma at the surface.

On 16 September 2014, provincial governor Joey Salceda said that the government would begin to "fast-track the preparation to evacuate 12,000 families in the 6-8 km extended danger zone", and soldiers would enforce the no-go areas.

On 18 September 2014, PHIVOLCS reported 142 VT earthquake events and 251 rockfall events during the past day. White steam plumes drifted to the south-southwest and rain clouds covered the summit. Sulfur dioxide (SO2) emission was measured at an 757 tonnes/day on 17 September 2014, after it had peaked at 2,360 tonnes/day on 6 September 2014. Ground deformation (precise leveling and tilt meters) during the 3rd week of August 2014 recorded edifice inflation.

Reference: http://en.wikipedia.org/wiki/Mayon_Volcano#cite_note-PhivolcsBulletin20-31 (Read all the info on the Recorded Eruptions). 

Monitoring Mayon:

Mayon Volcano is the most active volcano in the Philippines, and its activity is regularly monitored by PHIVOLCS from their provincial headquarters on Ligñon Hill, about 12 kilometres (7.5 mi) SSE from the summit. Three telemetric units are installed on Mayon's slopes, which send information to the seven seismometers in different locations around the volcano. These instruments relay data to the Ligñon Hill observatory and the PHIVOLCS central headquarters on the University of the Philippines Diliman campus. PHIVOLCS also deploys electronic distance meters (EDMs), precise leveling benchmarks, and portable fly spectrometers to monitor the volcano's daily activity.

Mayon Danger and Safe Zones, Evacuation Centers - Schadow1 Expeditions

Transmission of Warning:

At the five most active volcanoes being monitored by PHIVOLCS--Mayon, Bulusan, Taal, Hibok-Hibok, and Canlaon--eruption warnings are usually passed through the appropriate DCC. When one of these volcanoes manifests abnormal behavior, PHIVOLCS interprets its changing behavior and decides whether or not to send warnings and, if so, when. As soon as PHIVOLCS decides to issue a warning, it notifies the Office of the President and the national and local DCCs, through Volcano Bulletins and advisories that explain the condition of the volcano and recommended actions. The DCCs, in turn, transmit the warning to those at risk and respond in various other ways. Although transmission of warnings is officially the responsibility of the DCCs, PHIVOLCS observatory personnel help deliver warnings to nearby inhabitants. Later, PHIVOLCS' main office might release information to the media to clarify and explain the volcano's condition.

This warning procedure was modified in the case of Pinatubo. Warning messages were formulated at PHIVOLCS' main office and transmitted simultaneously through the DCC hierarchy, major national and local newspapers, radio and television stations, nongovernmental organizations (NGOs), and directly to the endangered inhabitants.

Multipath warning transmission has been found to create confusion, duplication, and administrative problems in some situations. This is why, at other monitored Philippine volcanoes, warnings and evacuation advice are passed, as much as possible, through the concerned DCCs. The effectiveness of the modified transmission procedure adopted at Pinatubo was assessed by use of two indicators: (1) consistency between the warning message released by the source (PHIVOLCS) and the message received by the recipients and (2) the time gap between issuance from the source and receipt by the target public.

Reference: http://pubs.usgs.gov/pinatubo/tayag/ 

MAYON VOLCANO BULLETIN 03 March 2015 8:00 A.M.

Mayon Volcano’s seismic monitoring network recorded three (3) volcanic earthquakes during the past 24 hours. Weak to moderate emission of white steam plumes that crept downslope and drifted towards west-northwest and northwest was observed. No crater glow was observed last night. Sulfur dioxide (SO2) emitted at the crater averaged 134 tonnes/day last 24 February 2015 was still below the baseline level during normal periods. Data from the ground deformation survey on January 20-31, 2015 indicated a deflation of the edifice relative to the November 27-29, 2014 survey, although the edifice remains inflated relative to baseline measurements beginning 2010. Data from continuous tilt monitoring indicate that magma has stalled deep beneath the northern flanks of the volcano, although the edifice is still inflated or swollen compared to baseline levels.

Mayon Volcano’s alert status is currently at Alert Level 2. This means the volcano is at a moderate level of magmatic unrest. Although the volcano is currently exhibiting low-level of seismic activity, ground deformation data indicate that eruptible magma had already accumulated the previous year beneath the edifice. Current conditions may still change and eventually lead to hazardous eruption. The public is still reminded to avoid entry into the 6-km Permanent Danger Zone or PDZ due to perennial hazards of rockfalls, avalanche, ash puffs and sudden steam-driven or phreatic eruptions at the summit area. Furthermore, people living in valleys and active river channels are cautioned to remain vigilant against sediment-laden streamflows and lahars in the event of prolonged and heavy rainfall. PHIVOLCS-DOST is closely monitoring Mayon Volcano’s activity and any new development will be immediately posted to all concerned.

Reference: http://www.phivolcs.dost.gov.ph/index.php?option=com_content&view=article&id=4328:mayon-volcano-bulletin-03-march-2015-800-am-&catid=70:latest-volcano-bulletin&Itemid=500008