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.

Tuesday, 13 June 2017

Natural Disasters and Family Misfortunes 4: Earthquakes

Among natural disasters, earthquakes rate right up top as the deadliest. Each year thousands of people are killed or left homeless. Whole families, and by extension family lines have been lost during these events. Current and historical records document the effects and aftermaths of these major intrusions of Mother Nature in the lives of humans.

Since the Earth is in a dynamic state, changes to its surface through such processes as land shifts will continue to happen and any communities or infrastructure, not to mention people it the way will in all likelihood be harmed.

The 1906 earthquake in the San Francisco area, mentioned briefly in my blog post of 18 April 2017, was felt along the entire north coast of California, particularly devastating the urban area of San Francisco where it destroyed 80% of the city. Over 3,000 people died as a result of the quake and its resultant fires.

Major earthquakes are concentrated along the edges of the Earth’s crustal plates where relative movements cause the plates to impinge on each other. California is a region where the North American and Pacific plates slide laterally in opposite directions, grinding against each other and creating major fractures and fault zones. Movement is frequent and never-ending, in a geological sense, resulting in severe tremors and vertical movement.
 
World map showing major crustal tectonic plates – source United States Geological Survey 
Along coastal areas tsunamis may form as a result of the shifting of the seabed, adding a secondary potential for destruction. These large ocean waves can travel thousands of miles across open water, eventually appearing along distant shorelines with highly destructive force.

There is an informative website that lists earthquakes by period, country and region and also compares the devastation in terms of magnitude, cost of damage and numbers of deaths. These are primarily events that occurred during more recent times and documented in the published literature. There is no doubt similar events occurred in the past centuries before mass media. One major difference is in the perceived human toll. The rapid and large increase in population of the past 150 years has led to more people and communities being caught up in the destruction with many more deaths and greater destruction of infrastructure.

Ancient writings, along with archaeological and geological studies demonstrate the occurrence of destructive earthquakes going back thousands of years many of which affected early communities. Turkey and Syria, for example, lie at the junction of three crustal plates – African, Arabian and Eurasian (Anatolian sub-plate). The region has been the site of numerable major earthquakes and volcanic eruptions over millions of years. Records dating back a thousand years describe the destruction from these events. Earthquakes centered near the Greco-Roman city of Antioch, in AD 115 and AD 526 each apparently resulted in the deaths of hundreds of thousands of people. The deadliest earthquake in recorded history occurred in Shaanxi, China in AD 1556 when over 830,000 people were killed.

Besides the well-documented 1906 San Francisco event, there have been many major earthquakes in North America including one in AD 1700 in Cascadia (Washington State & British Columbia). No written records exist from the time period in North America describing the earthquake, however, in Japan there are reports of a tsunami thought to have originated along the North American coast. Tree ring evidence from the Pacific Northwest also show a major disruption in forest growth from flooding of low-lying areas. The earthquake is believed to have been caused by the North American plate slipping over the Juan de Fuca plate with a major shift along the deep subduction zone.
 
Structure of the Cascadia region and history of major earthquakes – source United States Geological Survey

While earthquakes by themselves may not have been the primary reasons for the migration of people, they certainly have been the cause of the deaths of thousands and the early demise of family lines. Family historians may wish to look at natural disasters such as earthquakes when studying the reasons why ancestors died or moved. Such natural phenomena are often part of the stories about families.

Tuesday, 6 June 2017

Everyone is Related to Everyone

But what does that really mean? James Tanner commented in a recent blog post (Genealogy is not a competitive sport) about family trees that contain thousands of names. He also made the point that having those large numbers is, for all intents and purposes, meaningless.

Anyone can add names to their family tree. And many only do just (or only) that, regardless of whether they can justify relationships.

But so what! If you want to go back a few million years we can make a case that we are all related. In reality we can confidently only go back a few hundred years - perhaps 15 generations. Beyond the early part of the 16th century we are stretching credibility by listing ancestors or stating relationships. Few medieval records list the names of people, certainly true for the “common” people from whom most of us descend.

Many family historians want to latch on to the nobility which I think happens because only those few families published any kind of genealogical summaries. How many times have you seen someone’s tree that goes back to Charlemagne? That’s 30 to 40 generations.

Adam Rutherford poked a little fun about about relationships to the King of the Franks in a 24 May 2015 piece in The Guardian: So you’re related to Charlemagne? You and every other living European… He comments: “I am a direct descendent of someone of similar greatness: Charlemagne, Carolingian King of the Franks, Holy Roman Emperor, the great European conciliator. Quelle surprise!” He goes on to state, “This is merely a numbers game. You have two parents, four grandparents, eight great-grandparents, and so on. But this ancestral expansion is not borne back ceaselessly into the past. If it were, your family tree when Charlemagne was Le Grand Fromage would harbour more than a billion ancestors – more people than were alive then.”

The absence of true records of the greater proportion of the population over the centuries before about AD 1300 compels many people to attach themselves to those who have been named in formal documents. Seemingly, if you can trace a connection to any member of a European royal family then you are a descendant of Charlemagne (see Descendants of Charlemagne).
There is also an assumption that many members of ruling or royal families had scores of illegitimate children who somehow became the ancestors of so many of us. I seriously doubt that is true as there has always been a much larger number of people unrelated to those families. Their descendants would logically still make up most of the population today. Connections to any branch of royalty are often very tentative, perhaps even more like wishful thinking.

If you want to go back to Numero Uno in terms of human evolution then we can probably say we are all related. But that analysis is meaningless for family history studies. DNA may help us find or confirm some familial relationships within a few generations and among some close cousins but it won’t tell the whole story about our families and that is what we are really after, aren’t we?

There should be reservations even using DNA, assuming we could get samples from people as far back as the 9th century. One shares less than 1% of their DNA with their 6th great-grandparents which would make you wonder whether you can even truly demonstrate a blood relationship. The number is not even statistically relevant going back past 20 generations.

Going back to another post by James Tanner (Sourcecentric Genealogy), to conclusively show relationships or connections to past generations, one must work with bona fide historical records. Even some royal families’ trees or publication of them may be more fiction than fact so researchers must go beyond the summaries to find actual church or other records. And, again, any document dated earlier than the 14th century should be used with caution.


So, is everyone related to everyone else? Only in the most general, biological sense but not in any meaningful one with regard to family history!