The American Advanced National Seismic System (ANSS) donated the earthquake dataset that is used in the thesis. The origin of an earthquake is specified by three spatial dimensions, that is,focal Depth,Longitude-Latitudeepicenter coordinates, one temporal dimension (Time), and finally by the amount of energy (Magnitude) that is released by the earthquake.
In this work, a prominent earthquake catalog of California, Indonesia, Japan, Himalaya, Sumatra-Andaman, Taiwan, Switzerland, Philippines, and Iran are used to carry out the anal- ysis. These catalogs are accessed by Northern California Earthquake data center (NCEDC) through the website of NCEDC [4] after setting the appropriate parameters as mentioned in Table 2.6 for each catalog.
2.10.1 California
California has always been a hotbed of seismic activity where 15,000 fault lines are found throughout the region. Luckily about 500 faults are active at present, among them San Andreas fault line is the most active and dangerous which extends roughly 800 miles through California. The fault is approximately divided into three segments; each has different characteristics and degree of earthquake risk for the Californians. There is hardly any area of the state, that is completely immune to earthquakes but most significant is the southern segment which passes within 35 miles of Los Angeles. There have been lots of historic earthquakes recorded in the last few years like Loma Prieta earthquake (1989), Hector Mine (1992), Big Bear (1992), Landers (1992 ) and Northridge earthquake (1994).
2.10.2 Himalayan
The collision between two continental (Indian and Eurasian tectonic) plates released a lot of energy in the form of earthquakes which leads to the formation and uplift of Himalayan mountains. These mountains are the tallest and youngest on earth and the entire mountain range are very prone to earthquakes. Himalaya caught the public attention in the world due to frequently hike in seismic activities in the region. Mostly affected countries in the region are India, China, Pakistan, Afghanistan, and Nepal which causes widespread damage and loss of lives. The powerful earthquakes in the recent past like Uttarkashi (1991), Manyi (1997), Kunlun (2001), Kashmir (2005), Xingjiang (2008) and recent one Gorkha earthquake occurred in Nepal (2015) has made the Himalaya as a region of interest for many seismologists.
2.10 Earthquake catalogs 31
Table2.6Parametersettingtoobtaincatalogsusedinthestudy ParametersCatalogs CaliforniaHimalayaIndonesiaJapanSwitzerlandTaiwanPhilippinesIranSumatra-Andaman Starttime1991/01/011965/01/011965/01/011991/01/011990/01/011973/01/011966/01/011965/01/011965/01/01 00:00:0000:00:0000:00:0000:00:0000:00:0000:00:0000:00:0000:00:0000:00:00 Endtime2015/12/312015/12/312015/12/312012/12/312015/12/312015/12/312015/12/312015/12/312015/12/31 23:59:5923:59:5923:59:5923:59:5923:59:5923:59:5923:59:5923:59:5923:59:59 MinLat3220-12244519424-10 MaxLat37405464926244220 MinLon-122709512251171154290 MaxLon-1141001451461212713064100 MinDep000000000 MaxDep100383675.5683.39643007002501000 MinMag3.01.72.72.70.12.72.01.02.0 MaxMag6.77.89.09.15.57.787.910.0 EventtypeEEEEEEEEE
2.10.3 Indonesia
Indonesia is situated at the meeting point of the three major tectonic plates: Indo-Australian, Pacific, and Eurasian plates. The collision of these crustal plates makes responsible for the generation of a high subduction zone and therefore frequent tsunamis in the country.
Earthquakes like Biak (1996), Guinea (2002), Java (2006), Padang (2009), Sumatra-Andaman (2000, 2004, 2005, 2007), Papua (2015) are significant seismic activities in the past which makes the ideal catalog used for analysis.
2.10.4 Japan
The location of Japan lies along the Ring of Fire and makes the country highly prone to seis- mic activities in the world. Basically, Japan situated in the collision zone of continental and oceanic plates: Eurasian/Chinese plate, North American plate, Philippine plate, and Pacific plate. The movements of these plates released a lot of energy in the form of earthquakes followed by tsunamis in the country. Japan has experienced the highest number of natural disasters around the world in the last few years and thus essential to consider it in the thesis work. This catalog has a large number of significant earthquakes and tsunamis like Hokkaido (1993, 2003), Hyogo(1995), Miyakejima (2000), Chuetsu (2004), Iwate (2008) and Honsu (2013). On March 11, 2011, a deadly earthquake of magnitude about 9.1 occurred in the Tohoku which is the largest earthquake and tsunamis in the country.
2.10.5 Switzerland
Switzerland has moderate seismic activities which are mostly caused by collisions between the European and African lithospheric plates. Well-documented information of earthquake records in the Swiss catalog is a good test and a challenge to include in the analysis. In the catalog, most of the events have shallow focal depth and magnitude moderate to medium on Richter scale. The seismic activity in Switzerland and surrounding regions in the year 2003 was slightly above the average over the last couple of years.
2.10.6 Taiwan
Taiwan is located at the complex boundary between the Philippine Sea plate to the East and the Eurasian plate to the West. The collision of these two plates produces significant earthquakes and the region considered prone to seismic activities. This catalog has records of all major earthquakes like Tia-Tung (1996), Ryukyu Islands (1998), Chi-chi (1999), Nantou (2002, 2013), Tai-Tung (2003), Hengchun (2006), Kaohsiung (2010) and Hualien (2009,
2.10 Earthquake catalogs 33 2013, 2015). So it is a better choice to investigate the distribution of earthquakes as a function of space, time, and magnitude for realistic assessments of seismic hazards in Taiwan.
2.10.7 Philippines
The Philippines region is frequently affected by deadly typhoons, earthquakes, volcano eruptions, cyclone and other natural disasters due to its location along the ‘Ring of Fire.’
Here, the catalog used for analysis is restricted from Jan 1973 to Dec 2012 due to the presence of devastating earthquakes during the period. The historical Moro Gulf (1976), Luzon (1990) and Mindoro earthquake (1994), etc. are the strongest and deadliest earthquakes that caused major destruction in the Philippines and considered them in the analysis.
2.10.8 Iran
Iran straddles the seam between the Eurasian and Arabian tectonic plate and therefore prone to frequent and deadly tremors. In the region, major fault lines cover about 90 % of the country which produces earthquake often and more destructive. Most notably in the year 2003 with a magnitude 6.7 that disrupted the city of Bam and killed about 26,000 people.
Not only have earthquakes killed thousands, but they have also led to the waste of valuable natural resources. Another one, in the year 1990, with magnitude 7.4, near the Caspian Sea in Iran devastated the region and about 500,000 were made homeless, 50,000 died and 100,000 were injured.
2.10.9 Sumatra-Andaman
The complete Sumatra-Andaman belt is highly sensitive to tsunamis generated by moderate- to-large magnitude earthquake in the past which highly affects the adjacent countries like Indonesia, Sri Lanka, India, Maldives and Thailand. This region got the public attention in the world when one of the most powerful and destructive seismic events in history: Indian Ocean tsunami of 2004 (December 2004 Sumatra-Andaman earthquake) was recorded on a seismograph. It ruptured the greatest fault length of any recorded earthquake and triggered a series of tsunamis (that was up to 30m high along the northern coast of Sumatra), killing up to 280,000 people in 14 countries, and even displaced Earth’s the North Pole by 2.5cm.