February 19, 2015 Tsunami: Vanuatu Islands

A small scale local tsunami event has been confirmed on Paama. There are some reports of damage. (reference #11194)

Sea water receding c. 8 - 10 minutes after mainshock (eyewitnesses at Cave beach, Liro Nessa):

Cobbles rattles then soon after roaring sound

Most people in the village heard roaring sound

Tsunami event involves 3 waves (eyewitnesses):

1st after c. 10-12 minutes after mainshock

2nd much bigger than first wave after c. 8-10 minutes after 1st wave

Last wave after c. 10 minutes after 12

Tsunami struck at a time of abnormally very low tide conditions (eyewitnesses)

Generally, most people headed inland and uphill but fear of landslide.

(above from reference #11195)

On February 19, 2015 at 13:18 Universal time (February 19, 2015 at 00:18 local time), a powerful earthquake occurred offshore Northeast Paama and off north of Lopevi [Figure 12]. The Vanuatu Meteorology and Geohazards Department reported a magnitude of Ms 6.0 for the event and at a shallow depth of 10.0 km. No tsunami advisory or warning was issued for this event since the earthquake magnitude is below the threshold of magnitude 7.5 as per the Vanuatu Meteorology and Geohazards Forecast Section Standard Operating Procedures. Thus, no warning was issued for this event. It is the third known back-arc event that has generated a local tsunami; others being the 1999 Baie Martelli event and the 2012 Southeast Erromango event. A local tsunami struck the northern part of Paama and possibly Lopevi and Southeast Ambrym. Sea water receding c. 8 - 10 minutes after mainshock (eyewitnesses at Cave beach, Liro Nessa). Cobbles rattles (sea water receding) then soon after roaring sound. Most people in the village heard roaring sound. The tsunami event involves 3 waves (eyewitnesses); the first after c. 10-12 minutes after mainshock, the second wave is much bigger than first wave after c. 8-10 minutes after 1st wave and the last wave after c. 10 minutes later. The odd hour and tidal condition has much effect on tsunami impact. The tsunami struck at an abnormally low tide condition thus having huge impact on runups and inundation distances. Some preliminary observations of runup heights and inundation distances were made for coastlines of north and northwest Paama [Figure 13]. Runup heights of up to at least c. 8.0 m (inferred above low tide level at time of tsunami attack) and a maximum inundation distance of c. 150 m (inferred from low water level at time of tsunami attack). In some localities cobbles/boulders and beach sea oaks help protect the coastline. (reference #12086)

Tsunami runup heights, inundation heights and distances are high on the Northwest of the island, from Tavie to Liro Nessa. A tsunami flow depth of up to 2.0 m and a runup height of at least 6.0 m were measured [Figure 8]. Inundation distances of up to 120 m were observed on Northwest Paama. The tsunami struck at a time of abnormally very low tide conditions; lowest tide for the month of February 2015. (reference 12087)