Tuesday, 20 June 2017

Natural Disasters and Family Misfortunes 5: Tsunamis

I briefly mentioned tsunamis in my last post about earthquakes. They are spawned from major earthquakes that occur around the margins of the oceans, in particular the Pacific where the most active crustal plates are present.

2011 Japan – Earthquake and Tsunami

We were on a cruise ship on 11 March 2011 when a major earthquake and tsunami hit Japan. It did not impact us in any way, other than delaying the ship leaving Manilla harbour, but other family members were worried when they heard the news. Our daughter actually phoned us while we were on a bus coming back from shopping to find out where we were exactly and if we were OK. We relayed the news of the event to other shocked passengers.
A tsunami reaches Miyako City, overtopping seawalls and flooding streets in Iwate Prefecture, Japan, after the magnitude 9.0 earthquake struck the area; source The Atlantic
As it turned out the wave that hit Manilla was no more than a foot or two in height. Other areas around the margins of the Pacific were not so fortunate, particularly the coastline of Japan. The confirmed death toll in Japan is estimated to have been around 16,000 with another 2,500 people missing. An earthquake and tsunami in the same region in 1896 killed 27,000.
Graphic of Honshu Tsunami energy flux and deep water wave heights – image courtesy National Oceanic and Atmospheric Administration and Scientific American 

2004 Sumatra Earthquake and Tsunami

Our family was also sitting on a beach in Cuba when the 2014 Boxing Day (26 December) tsunami destroyed many communities in the Indian Ocean. We wondered then what might have happened if the earthquake and wave had originated somewhere in the Caribbean. Around the Indian Ocean, over a quarter million people perished!
Map of Indian Ocean showing location of the major 9.1-9.3 (Richter Scale) magnitude earthquake on 26 December 2004, death toll and damage from the resulting tsunami (Reuters) 
The district of Banda Aceh in Aceh province, located on Indonesia's Sumatra Island, just days after the earthquake and massive tsunami of 2004; source Australian Geographic

Tsunamis in History: 1607 Bristol Channel, England Earthquake and Tsunami

These are, of course, very recent events and may have little to do with family history research. They do illustrate, however, what might have happened when such events occurred in the past.

A major flood was reported in southwest England in 1607 that is believed by many researchers to have been a tsunami. No technology, of course, existed at the time to record a seismic event, nor was any such event reported. In the absence of any evidence of tectonic activity it is difficult to rationalize the flood being a tsunami. Differing meteorological accounts support either interpretation. Flooded areas extended 250 miles along both sides of the Bristol Channel/Severn Estuary in place spreading inland almost 30 miles. Flood heights reached over 25 feet in some localities with water covering nearly 400 square miles (250,000 acres). Parish registers and other local accounts attest to the damage done by the flood. From a variety of sources and publications it has been suggested that the death toll was between 500 and 2,000.
Depiction of the 1607 flood from a pamphlet printed in London
1755 Lisbon, Portugal Earthquake and Tsunami

On 1 November 1755 Lisbon, Portugal was rocked by an earthquake probably in the magnitude of 8.5 to 9.0 on the Richter scale. Three distinct shocks were occurred over a 10 minute interval. The quake was felt as well 400 miles to the south in North Africa; Algiers was totally destroyed; Tangiers suffered significant damage. Many of Lisbon’s major buildings collapsed, killing thousands under the debris. Fire broke out in many areas gradually spreading until most of the city was engulfed in flame. Over 80% of Lisbon’s buildings were destroyed.

The earthquake was centred about 120 miles to the southwest of the city, along a major fault in the Earth’s crust. The movement between tectonic plates resulted in a major tsunami that rolled over the coastline, trapping thousands of people that had fled from collapsed and burning buildings. It has been estimated that between 60,000 and 100,000 people died from a combination of building destruction, fire and flood. The tsunami wave was recorded in many places along the European coastline.
A copper engraving made in 1755 shows the city in ruins and in flames. Tsunamis rush upon the shore, destroying the wharfs. The engraving is also noteworthy in showing highly disturbed water in the harbor, which sank many ships. Passengers in the left foreground show signs of panic. Original in: Museu da Cidade, Lisbon.
1960 Chile Earthquake and Tsunami

The 1960 earthquake in Chile was the most powerful earthquake ever recorded, at 9.4–9.6 on the moment magnitude scale. It lasted approximately 10 minutes. A resulting tsunami affected southern Chile, Hawaii, Japan, the Philippines, eastern New Zealand, southeast Australia and the Aleutian Islands.

Waves as high as 82 feet battered the Chilean coast; waves up to 35 feet were recorded 6,200 miles from the epicenter. Estimates of the death toll range from 1,000 to 6,000. About 40 percent of the houses in Valdivia were destroyed and 20,000 people left homeless.
Using historical data, NOAA plotted the maximum amplitude for the tsunami waves generated by the 1960 Chile earthquake.  (Image:  National Oceanic and Atmospheric Administration Center for Tsunami Research)
Downtown Hilo, Hawaii, was left devastated by the tsunami. Photo Credit: The Honolulu Advertiser
The main quake on 22 May was preceded and followed by other major events. There was also a volcanic eruption about 150 miles to the southeast two days later that is likely related to the earthquake event.

1964 Alaska Earthquake and Tsunami

Readers may remember the earthquake that hit Alaska in 1964. The 9.2 magnitude earthquake struck near Anchorage causing significant damage and 139 deaths. It was the most powerful earthquake recorded in North America. Several tsunamis were produced, travelling across the Pacific. The largest wave was recorded in Shoup Bay, Alaska, with a height of about 220 feet.
Chaotic condition of the commercial section of the city of Kodiak following inundation by seismic sea waves. The small-boat harbor, which was in left background, contained an estimated 160 crab and salmon fishing boats when the waves struck. Tsunamis washed many vessels into the heart of Kodiak. Photo by U.S. Navy, March 30, 1964. 

Like the earthquakes they are related to, tsunamis have had devastating consequences on communities they have struck throughout history. Family researchers who had ancestors living in coastal areas, particularly in tectonically-active regions might think about whether such events impacted their families.